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the observation of light superpartners from a supersymmetric extension to the standard model is an intensely sought-after experimental outcome, providing an explanation for the stabilization of the electroweak scale and indicating the existence of new particles which could be consistent with dark matter phenomenology. for compressed scenarios, where sparticle spectra mass splittings are small and decay products carry low momenta, dedicated techniques are required in all searches for supersymmetry. in this paper we suggest an approach for these analyses based on the concept of recursive jigsaw reconstruction, decomposing each event into a basis of complementary observables, for cases where strong initial state radiation has sufficient transverse momentum to elicit the recoil of any final state sparticles. we introduce a collection of kinematic observables which can be used to probe compressed scenarios, in particular exploiting the correlation between missing momentum and that of radiative jets. as an example, we study squark and gluino production, focusing on mass-splittings between parent superparticles and their lightest decay products between 25 and 200 gev, in hadronic final states where there is an ambiguity in the provenance of reconstructed jets. | sparticles in motion: analyzing compressed susy scenarios with a new method of event reconstruction |
in the supersymmetric models, the coannihilation of the neutralino dm with a lighter supersymmetric particle provides a feasible way to accommodate the observed cosmological dm relic density. such a mechanism predicts a compressed spectrum of the neutralino dm and its coannihilating partner, which results in the soft final states and makes the searches for sparticles challenging at colliders. on the other hand, the abundance of the freeze-out neutralino dm usually increases as the dm mass becomes heavier. this implies an upper bound on the mass of the neutralino dm. given these observations, we explore the he-lhc coverage of the neutralino dm for the coannihilations. by analyzing the events of the multijet with the missing transverse energy (etmiss), the monojet, the soft lepton pair plus etmiss, and the monojet plus a hadronic tau, we find that the neutralino dm mass can be excluded up to 2.6, 1.7 and 0.8 tev in the gluino, stop and wino coannihilations at the 2 σ level, respectively. however, there is still no sensitivity of the neutralino dm in stau coannihilation at the he-lhc, due to the small cross section of the direct stau pair production and the low tagging efficiency of soft tau from the stau decay. | on the coverage of neutralino dark matter in coannihilations at the upgraded lhc |
we investigate a simple variant of type-ii seesaw, responsible for neutrino mass generation, where the particle spectrum is extended with one singlet right-handed neutrino and an inert higgs doublet, both odd under an additional z2 symmetry. while the role of the dark matter is played by the lightest neutral component of the inert higgs doublet (ihd), its interaction with the standard model lepton doublets and the right-handed neutrino turns out to be crucial in generating the correct baryon abundance of the universe through flavored leptogenesis from the decay of the s u (2 )l scalar triplet, involved in type-ii framework. we observe a correlation between the smallness of the mass splitting, among the dark matter and the c p -odd neutral scalar from the ihd, and the largeness of the mass of the triplet followed from the dominance of the type-ii mechanism over the radiative contribution to neutrino mass. | scalar triplet flavor leptogenesis with dark matter |
a key assumption of the standard cosmological model is that the temperature of the cosmic microwave background (cmb) radiation scales with cosmological redshift $z$ as $t_{\rm cmb}(z) \propto (1+z)$ at all times after recombination at $z_\star \simeq 1090$. however, this assumption has only been precisely tested at $z \lesssim 3$. here, we consider cosmological models with post-recombination reheating (prr), in which the cmb monopole temperature abruptly increases due to energy injection after last scattering. such a scenario can potentially resolve tensions between inferences of the current cosmic expansion rate (the hubble constant, $h_0$). we consider an explicit model in which a metastable sub-component of dark matter (dm) decays to standard model photons, whose spectral energy distribution is assumed to be close to that of the cmb blackbody. a fit to planck cmb anisotropy, cobe/firas cmb monopole, and sh0es distance-ladder measurements yields $h_0 = 71.2 \pm 1.1$ km/s/mpc, matter fluctuation amplitude $s_8 = 0.774 \pm 0.018$, and cmb temperature increase $\delta t_{\rm cmb} = 0.109^{+0.033}_{-0.044}$ k, which is sourced by dm decay at $z \gtrsim 10$. however, matter density constraints from baryon acoustic oscillation and supernovae data highly constrain this scenario, with a joint fit to all datasets yielding $h_0 = 68.69 \pm 0.35$ km/s/mpc, $s_8 = 0.8035 \pm 0.0081$, and $\delta t_{\rm cmb} < 0.0342$ k (95% cl upper limit). these bounds can be weakened if additional dark relativistic species are present in the early universe, yielding higher $h_0$. we conclude that current data disfavor models with significant prr solely through its impact on background and linear-theory observables, completely independent of cmb spectral distortion constraints. however, a small amount of such energy injection could play a role in restoring cosmological concordance. | did the universe reheat after recombination? |
a search for dijet resonances in events with at least one isolated charged lepton is performed using $139~{\text{fb}}^{-1}$ of $\sqrt{s}=13$ tev proton-proton collision data recorded by the atlas detector at the lhc. the dijet invariant-mass ($m_{jj}$) distribution constructed from events with at least one isolated electron or muon is searched in the region $0.22 < m_{jj} < 6.3$ tev for excesses above a smoothly falling background from standard model processes. triggering based on the presence of a lepton in the event reduces limitations imposed by minimum transverse momentum thresholds for triggering on jets. this approach allows smaller dijet invariant masses to be probed than in inclusive dijet searches, targeting a variety of new-physics models, for example ones in which a new state is produced in association with a leptonically decaying $w$ or $z$ boson. no statistically significant deviation from the standard model background hypothesis is found. limits on contributions from generic gaussian signals with widths ranging from that determined by the detector resolution up to 15% of the resonance mass are obtained for dijet invariant masses ranging from 0.25 tev to 6 tev. limits are set also in the context of several scenarios beyond the standard model, such as the sequential standard model, a technicolor model, a charged higgs boson model and a simplified dark matter model. | search for dijet resonances in events with an isolated charged lepton using $\\sqrt{s} = 13$ tev proton-proton collision data collected by the atlas detector |
we describe the automation of the calculation of perturbative unitarity constraints including scalars that have colour charges, and its release in sarah4.14.4. we apply this, along with vacuum stability constraints, to a simple dark matter model with colourful mediators and interesting decays, and show how it leads to a bound on a thermal relic dark matter mass well below the classic griest-kamionkowski limit. | how heavy can dark matter be? constraining colourful unitarity with sarah |
decaying cold dark matter (dcdm) is a model that is currently under investigation regarding primarily the s 8 tension between cosmic microwave background (cmb) and certain large-scale structure measurements. the decay into one massive and one (or more) massless daughter particle(s) leads to a suppression of the power spectrum in the late universe that depends on the relative mass splitting ϵ = (1 - m 2/m 2)/2 between the mother and massive daughter particle as well as the lifetime τ. in this work we investigate the impact of the boss dr14 one-dimensional lyman-α forest flux power spectrum on the dcdm model using a conservative effective model approach to account for astrophysical uncertainties. since the suppression of the power spectrum due to decay builds up at low redshift, we find that regions in parameter space that address the s 8 tension can be well compatible with the lyman-α forest. nevertheless, for values of the degeneracy parameter ϵ ~ 0.1-0.5%, for which the power suppression occurs within the scales probed by boss lyman-α data, we find improved constraints compared to previous cmb and galaxy clustering analyses, obtaining τ ≳ 18 gyrs for small mass splitting. furthermore, our analysis of the boss lyman-α flux power spectrum allows for values τ ~ 102 gyrs, ϵ ~ 1%, that have been found to be preferred by a combination of planck and galaxy clustering data with a kids prior on s 8, and we even find a hint for a marginal preference within this regime. | decaying dark matter and lyman-α forest constraints |
a search for dark matter is conducted in events with large missing transverse momentum and a hadronically decaying, lorentz-boosted top quark. this study is performed using proton-proton collisions at a center-of-mass energy of 13 tev, in data recorded by the cms detector in 2016 at the lhc, corresponding to an integrated luminosity of 36 fb-1. new substructure techniques, including the novel use of energy correlation functions, are utilized to identify the decay products of the top quark. with no significant deviations observed from predictions of the standard model, limits are placed on the production of new heavy bosons coupling to dark matter particles. for a scenario with purely vector-like or purely axial-vector-like flavor changing neutral currents, mediator masses between 0.20 and 1.75 tev are excluded at 95% confidence level, given a sufficiently small dark matter mass. scalar resonances decaying into a top quark and a dark matter fermion are excluded for masses below 3.4 tev, assuming a dark matter mass of 100 gev. | search for dark matter in events with energetic, hadronically decaying top quarks and missing transverse momentum at √{s}=13 tev |
we present an experimental and theoretical study of hydrodynamic phenomena in a two-component atomic bose-einstein condensate emerging from the imprinting of a periodic spin pattern. by employing a microwave pulse-based winding technique, we prepare a tunable initial state which evolves into an array of solitary waves. we observe the ensuing dynamics, including shape deformations, the emergence of dark-antidark solitons, apparent spatial frequency tripling, and decay and revival of contrast related to soliton collisions. for the densest arrays, we obtain soliton complexes where solitons undergo continued collisions for long evolution times providing an avenue towards the investigation of soliton gases in atomic condensates. | observation of dense collisional soliton complexes in a two-component bose-einstein condensate |
motivated by the recently proposed trans-planckian censorship conjecture (tcc), we propose a gauged $b-l$ model of inflection-point inflation with axion dark matter. the hubble scale during inflation ($h_{\rm inf}$) satisfies the tcc bound of $h_{\rm inf} \lesssim 1$ gev, the axion dark matter scenario is free from the axion domain wall and isocurvature problems, and the axion decay constant can be larger than $10^{12}$ gev. the seesaw mechanism is automatically incorporated in the model and the observed baryon asymmetry of the universe can be reproduced via resonant leptogenesis. | inflection-point inflation with axion dark matter in light of trans-planckian censorship conjecture |
we consider oscillons — localized, quasiperiodic, and extremely long-living classical solutions in models with real scalar fields. we develop their effective description in the limit of large size at finite field strength. namely, we note that nonlinear long-range field configurations can be described by an effective complex field ψ(t,x) which is related to the original fields by a canonical transformation. the action for ψ has the form of a systematic gradient expansion. at every order of the expansion, such an effective theory has a global u(1) symmetry and hence a family of stationary nontopological solitons — oscillons. the decay of the latter objects is a nonperturbative process from the viewpoint of the effective theory. our approach gives an intuitive understanding of oscillons in full nonlinearity and explains their longevity. importantly, it also provides reliable selection criteria for models with long-lived oscillons. this technique is more precise in the nonrelativistic limit, in the notable cases of nonlinear, extremely long-lived, and large objects, and also in lower spatial dimensions. we test the effective theory by performing explicit numerical simulations of a (d + 1)-dimensional scalar field with a plateau potential. | an effective field theory for large oscillons |
we develop an effective field theory (eft) framework for superfluid 4he to model the interactions among quasiparticles, helium atoms and probe particles. our effective field theory approach brings together symmetry arguments and power-counting and matches to classical fluid dynamics. we then present the decay and scattering rates for the relevant processes involving quasiparticles and helium atoms. the presented eft framework and results can be used to understand the dynamics of thermalization in the superfluid, and can be further applied to sub-gev dark matter direct detection with superfluid 4he. | superfluid effective field theory for dark matter direct detection |
postinflationary reheating is a widely discussed mechanism for nonthermal production of dark matter (dm). in this scenario the momentum distribution of the produced dm particles is usually taken to be the one obtained at reheating, redshifted at later times due to the expansion of the universe. however, since in such a scenario both the dm and the standard model (sm) fields couple to the inflaton, the dm particles necessarily undergo self-scatterings, as well as elastic and inelastic scattering reactions with the sm bath, all of which proceed through s -channel or t -channel inflaton exchange. we compute the momentum distribution of the dm particles including the effect of these scatterings, and find that the distributions can be significantly altered, even though dm remains nonthermal throughout the cosmological evolution. we observe that if the inflaton dominantly couples to the sm higgs boson through a renormalizable interaction, then reheating temperatures and inflaton masses at the tev scale lead to a large effect from the scattering processes, with the dm-inflaton coupling constrained by the dm density. the scattering effects are found to be sensitive to the duration of the reheating process—larger the duration, more momentum modes are filled at reheating, leading to an enhanced scattering probability. we also obtain the free-streaming length of such dm using the resulting nonthermal momentum distribution, which can be used to estimate the implications of the lyman-α constraints on the dm mass. it is observed that in the scenarios considered, including the scattering effects can reduce the dm average velocity at matter-radiation equality, and its free-streaming length, by up to a factor of 40, thereby making the constraints on light dm produced in inflaton decay significantly weaker. | momentum distribution of dark matter produced in inflaton decay: effect of inflaton mediated scatterings |
we consider inelastic dark matter scenarios with dark photon mediator and a dark higgs boson. the dark higgs boson spontaneously breaks the gauge symmetry associated with the dark photon, and gives the mass to the dark photon and the mass difference to dark particles. such a dark higgs boson can decay into the dark particles and hence can be another source of the dark particles at collider experiments. we analyze the sensitivity to decays of the excited state into the dark matter and charged particles at the faser 2 experiment in fermion and scalar inelastic dark matter scenarios. we consider two mass spectra as illustrating examples in which the excited state can be produced only through the decay of dark higgs boson. we show that unprobed parameter region can be explored in fermion dark matter scenario for the illustrating mass spectra. | inelastic dark matter from dark higgs boson decays at faser |
the flux of high-energy astrophysical γ rays is attenuated by the production of electron-positron pairs from scattering off of extragalactic background light (ebl). we use the most up-to-date information on galaxy populations to compute their contributions to the pair-production optical depth. we find that the optical depth inferred from γ -ray measurements exceeds that expected from galaxies at the ∼2 σ level. if the excess is modeled as a frequency-independent re-scaling of the standard contribution to the ebl from galaxies, then an excess (an overall 14-30% increase of the ebl) is favored over the null hypothesis of no excess at the 2.7 σ level. if the frequency dependence of the excess is instead modeled as a two-photon decay of a dark-matter axion, then the excess is favored over the null hypothesis at the 2.1 σ confidence level. while we find no evidence for a dark-matter signal, the analysis sets the strongest current bounds on the photon-axion coupling over the 8-25 ev mass range. this work highlights the sensitivity of γ -ray optical depth measurements to alps, which is expected to improve with new observatories and better ebl determinations from future observations. | seeking dark matter with γ -ray attenuation |
we report on the first belle search for a light c p -odd higgs boson, a0, that decays into low mass dark matter, χ , in final states with a single photon and missing energy. we search for events produced via the dipion transition ϒ (2 s )→ϒ (1 s )π+π- , followed by the on-shell process ϒ (1 s )→γ a0 with a0→χ χ , or by the off-shell process ϒ (1 s )→γ χ χ . utilizing a data sample of 157.3 ×106 ϒ (2 s ) decays, we find no evidence for a signal. we set limits on the branching fractions of such processes in the mass ranges ma0<8.97 gev /c2 and mχ<4.44 gev /c2 . we then use the limits on the off-shell process to set competitive limits on wimp-nucleon scattering in the wimp mass range below 5 gev /c2. | search for a light c p -odd higgs boson and low-mass dark matter at the belle experiment |
we study collider signatures of a class of dark matter models with a gev-scale dark z '. at hadron colliders, the production of dark matter particles naturally leads to associated production of the z ', which can appear as a narrow jet after it decays hadronically. contrary to the usual mono-jet signal from initial state radiation, the final state radiation of dark matter can generate the signature of a mono- z ' jet plus missing transverse energy. performing a jet-substructure analysis to tag the z ' jet, we show that these z ' jets can be distinguished from qcd jets at high significance. compared to mono-jets, a dedicated search for mono- z ' jet events can lead to over an order of magnitude stronger bounds on the interpreted dark matter-nucleon scattering cross sections. | dark matter searches with a mono-z' jet |
collective excitations, such as vortex-antivortex and dark solitons, are among the most fascinating effects of macroscopic quantum states. however, two-dimensional (2d) dark solitons are unstable and collapse into vortices due to snake instabilities. making use of the optical bistability in exciton-polariton microcavities, we demonstrate that a pair of dark solitons can be formed in the wake of an obstacle in a polariton flow resonantly supported by a homogeneous laser beam. unlike the purely dissipative case where the solitons are gray and spatially separate, here the two solitons are fully dark, rapidly align at a specific separation distance, and propagate parallel as long as the flow is in the bistable regime. remarkably, the use of this regime allows us to relax the phase fixing constraints imposed by the resonant pumping and to circumvent the polariton decay. our work opens very wide possibilities for studying new classes of phase-density defects which can form in driven-dissipative quantum fluids of light. | parallel dark-soliton pair in a bistable two-dimensional exciton-polariton superfluid |
we propose a new class of metastable dark energy (de) phenomenological models in which the de decay rate does not depend on external parameters such as the scalefactor or the curvature of the universe. instead, the de decay rate is assumed to be a constant depending only on intrinsic properties of de and the type of a decay channel, similar to case of the radioactive decay of unstable particles and nuclei. as a consequence, the de energy density becomes a function of the proper time elapsed since its formation, presumably in the very early universe. such a natural type of de decay can profoundly affect the expansion history of the universe and its age. metastable de can decay in three distinct ways: (i) exponentially, (ii) into dark matter, (iii) into dark radiation. testing metastable de models with observational data, we find that the decay half-life must be many times larger than the age of the universe. models in which de decays into dark matter lead to lower values of the hubble parameter at large redshifts relative to λ cold dark matter (cdm). consequently these models provide a better fit to cosmological bao data (especially data from high-redshift quasars) than concordance (λcdm) cosmology. | metastable dark energy with radioactive-like decay |
controls on the degradation of dissolved organic matter (dom) are complex but key to understand the role of freshwaters in the carbon cycle. both the origin and previous degradation history have been suggested to determine dom reactivity, but it is still a major challenge to understand the links between dom composition and biodegradation kinetics. an appropriate context to study these links are intermittent rivers, as summer drought naturally diversifies dom sources and sinks. here we investigated the biodegradation kinetics of dom in the main aquatic environments present in a temporary river. during dark incubations we traced the dynamics of bulk dom and its main chromatographic fractions defined using lc-ocd: high molecular weight substances (hmws), low molecular weight substances (lmws), and humic substances and building blocks. bulk dom decay patterns were successfully fitted to the reactivity continuum (rc) biodegradation model. the rc parameters depicted running waters as the sites presenting a more reactive dom, and temporary pools, enriched in leaf litter, as the ones with slowest dom decay. the decay patterns of each dom fraction were consistent throughout sites. lmws and hmws decayed in all cases and could be modeled using the rc model. notably, the dynamics of lmws controlled the bulk dom kinetics. we discuss the mechanistic basis for the chromatographic fractions' kinetics during biodegradation and the implications that preconditioning and summer drought can have for dom biodegradation in intermittent rivers. | biodegradation kinetics of dissolved organic matter chromatographic fractions in an intermittent river |
the simplest way to create sterile neutrinos in the early universe is by their admixture to active neutrinos. however, this mechanism, connected to the dark matter (dm) problem by dodelson and widrow (dw), cannot simulatenously meet the relic abundance constraint as well as bounds from structure formation and x-rays. nonetheless, unless a symmetry forces active-sterile mixing to vanish exactly, the dw mechanism will unavoidably affect the sterile neutrino dm population created by any other production mechanism. we present a semi-analytic approach to the dw mechanism acting on an arbitrary initial abundance of sterile neutrinos, allowing to combine dw with any other preceeding production mechanism in a physical and precise way. while previous analyses usually assumed that the spectra produced by dw and another mechanism can simply be added, we use our semi-analytic results to discuss the validity of this assumption and to quantify its accurateness, thereby also scrutinising the dw spectrum and the derived mass bounds. we then map our results to the case of sterile neutrino dm from the decay of a real sm singlet coupled to the higgs. finally, we will investigate aspects of structure formation beyond the usual simple free-streaming estimates in order to judge on the effects of the dw modification on the sterile neutrino dm spectra generated by scalar decay. | dodelson-widrow production of sterile neutrino dark matter with non-trivial initial abundance |
we reanalyze the effective field theory approach for the scenario in which the particles that account for the dark matter (dm) in the universe are vector states that interact only or mainly through the standard model-like higgs boson observed at the lhc. this model-independent and simple approach, with a minimal set of new input parameters, is widely used as a benchmark in dm searches and studies in astroparticle and collider physics. we show that this effective theory could be the limiting case of ultraviolet complete models, taking as an example the one based on a spontaneously broken u(1) gauge symmetry that incorporates a dark gauge boson and an additional scalar that mixes with the standard higgs boson. hence, despite the presence of the new degrees of freedom, measurements of the invisible decay branching ratio of the higgs boson, as performed at colliders such as the cern lhc, can be interpreted consistently in such an effective framework and can be made complementary to results of dm searches in direct detection experiments. | the higgs-portal for vector dark matter and the effective field theory approach: a reappraisal |
we derive the shafieloo, hazra, sahni and starobinsky (shss) phenomenological formula for the radioactive-like decay of metastable dark energy directly from the principles of quantum mechanics. to this aim we use the fock-krylov theory of quantum unstable states. we obtain deeper insight on the decay process as having three basic phases: the phase of radioactive decay, the next phase of damping oscillations, and finally the phase of power-law decay. we consider the cosmological model with matter and dark energy in the form of decaying metastable dark energy and study its dynamics in the framework of non-conservative cosmology with an interacting term determined by the running cosmological parameter. we study the cosmological implications of metastable dark energy and estimate the characteristic time of ending of the radioactive-like decay epoch to be 2.2× 10^4 of the present age of the universe. we also confront the model with astronomical data which show that the model is in good agreement with the observations. our general conclusion is that we are living in the epoch of the radioactive-like decay of metastable dark energy which is a relict of the quantum age of the universe. | quantum mechanical look at the radioactive-like decay of metastable dark energy |
two-neutrino double electron capture ($2\nu$ecec) is a second-order weak process with predicted half-lives that surpass the age of the universe by many orders of magnitude. until now, indications for $2\nu$ecec decays have only been seen for two isotopes, $^{78}$kr and $^{130}$ba, and instruments with very low background levels are needed to detect them directly with high statistical significance. the $2\nu$ecec half-life provides an important input for nuclear structure models and its measurement represents a first step in the search for the neutrinoless double electron capture processes ($0\nu$ecec). a detection of the latter would have implications for the nature of the neutrino and give access to the absolute neutrino mass. here we report on the first direct observation of $2\nu$ecec in $^{124}$xe with the xenon1t dark matter detector. the significance of the signal is $4.4\sigma$ and the corresponding half-life $t_{1/2}^{2\nu\text{ecec}} = (1.8\pm 0.5_\text{stat}\pm 0.1_\text{sys})\times 10^{22}\;\text{y}$ is the longest ever measured directly. this study demonstrates that the low background and large target mass of xenon-based dark matter detectors make them well suited to measuring other rare processes as well, and it highlights the broad physics reach for even larger next-generation experiments. | first observation of two-neutrino double electron capture in $^{124}$xe with xenon1t |
we discuss collider search strategies of gluinos which are highly degenerate with the lightest neutralino in mass. this scenario is fairly difficult to probe with conventional search strategies at colliders, and thus may provide a hideaway of supersymmetry. moreover, such a high degeneracy plays an important role in dark matter physics as the relic abundance of the lightest neutralino is significantly reduced via coannihilation. in this paper, we discuss ways of uncovering this scenario with the help of longevity of gluinos; if the mass difference between the lightest neutralino and gluino is ≲ 100 gev and squarks are heavier than gluino, then the decay length of the gluino tends to be of the order of the detector-size scale. such gluinos can be explored in the searches of displaced vertices, disappearing tracks, and anomalously large energy deposit by (meta)stable massive charged particles. we find that these searches are complementary to each other, and by combining their results we may probe a wide range of the compressed gluino region in the lhc experiments. | cornering compressed gluino at the lhc |
limits on the cross section for weakly interacting massive particles (wimps) elastic scattering on nuclei in nai(tl) detectors at the yangyang underground laboratory are obtained from a 2967.4 kg·day data exposure. the nuclei recoiling from the scattering process are identified by the pulse shape of the scintillation light signals that they produce. the data are consistent with a no nuclear-recoil hypothesis, and wimp-mass-dependent 90% confidence-level upper-limits are set on wimp-nuclei elastic scattering cross sections. these limits partially exclude the dama/libra allowed region for wimp-sodium interactions with the same nai(tl) target material. the 90% confidence level upper limit on the wimp-nucleon spin-independent cross section is 3.26×10-4 pb for a wimp mass of 10 gev/c2. | limits on interactions between weakly interacting massive particles and nucleons obtained with nai(tl) crystal detectors |
a search for dark matter produced in association with top quarks in proton-proton collisions at a center-of-mass energy of 13 tev is presented. the data set used corresponds to an integrated luminosity of 35.9 fb-1 recorded with the cms detector at the lhc. whereas previous searches for neutral scalar or pseudoscalar mediators considered dark matter production in association with a top quark pair only, this analysis also includes production modes with a single top quark. the results are derived from the combination of multiple selection categories that are defined to target either the single top quark or the top quark pair signature. no significant deviations with respect to the standard model predictions are observed. the results are interpreted in the context of a simplified model in which a scalar or pseudoscalar mediator particle couples to a top quark and subsequently decays into dark matter particles. scalar and pseudoscalar mediator particles with masses below 290 and 300 gev, respectively, are excluded at 95% confidence level, assuming a dark matter particle mass of 1 gev and mediator couplings to fermions and dark matter particles equal to unity. | search for dark matter produced in association with a single top quark or a top quark pair in proton-proton collisions at √{s}=13 tev |
temporary matter domination and late entropy dilution, injected by a "long-lived" particle in the early universe, serves as a standard mechanism for yielding the correct dark matter relic density. we recently pointed out the cosmological significance of diluting particle's partial decay into dark matter. when repopulated in such a way, dark matter carries higher momentum than its thermal counterpart, resulting in a suppression of the linear matter power spectrum that is constrained by the large scale structure observations. in this work, we study the impact of such constraints on the minimal left-right symmetric model that accounts for the origin of neutrino mass. we map out a systematic anatomy of possible dilution scenarios with viable parameter spaces, allowed by cosmology and various astrophysical and terrestrial constraints. we show that to accommodate the observed dark matter relic abundance the spontaneous left-right symmetry breaking scale must be above pev and cosmology will continue to provide the most sensitive probes of it. in case the dilutor is one of the heavier right-handed neutrinos, it can be much lighter and lie near the electroweak scale. | anatomy of diluted dark matter in the minimal left-right symmetric model |
we report on the design and performance of the lux-zeplin (lz) "screener", a small liquid scintillator detector consisting of ≈ 23 kg of lab-based gadolinium-loaded liquid scintillator (gdls) to be used in the lz outer detector. the outer detector will be filled with 17.3 tonnes of gdls and will surround the central liquid xenon time projection chamber of lz. its primary function will be to tag neutron events in the liquid xenon which could mimic a wimp dark matter signal. to meet the deadtime requirements for the outer detector, the radioimpurity levels in the gdls must be kept below ≲ 0 . 07 mbq/kg. this background level corresponds to a rate of ≈ 50 hz above an energy threshold of 100 kev. the screener was operated in the ultra-low-background environment of the former lux water shield in the davis laboratory at the sanford underground research facility for radioassay of the gdls. careful selection of detector materials and use of ultra-low-background pmts allows the measurement of a variety of radioimpurities. the 14c/12c ratio in the scintillator is measured to be (2 . 83 ± 0 . 06(stat.) ± 0 . 01(sys.)) × 10-17. use of pulse shape discrimination allows the concentration of isotopes throughout the 238u, 235u, and 232th chains to be measured by fitting the collected spectra from α and β events. we find that equilibrium is broken in the 238u and 232th chains and that a significant portion of the contamination in the gdls results from decays in the 227ac subchain of the 235u series. predictions for the singles rate in the outer detector are presented. the rate from radioimpurities above 100 kev in the gdls is estimated to be 97 . 9 ± 6 . 4 hz, with 65 . 5 ± 1 . 9 hz resulting from α-decays. | a liquid scintillation detector for radioassay of gadolinium-loaded liquid scintillator for the lz outer detector |
we discuss the relevance of directional detection experiments in the post-discovery era and propose a method to extract the local dark matter phase space distribution from directional data. the first feature of this method is a parameterization of the dark matter distribution function in terms of integrals of motion, which can be analytically extended to infer properties of the global distribution if certain equilibrium conditions hold. the second feature of our method is a decomposition of the distribution function in moments of a model independent basis, with minimal reliance on the ansatz for its functional form. we illustrate our method using the via lactea ii n-body simulation as well as an analytical model for the dark matter halo. we conclude that {o}(1000) events are necessary to measure deviations from the standard halo model and constrain or measure the presence of anisotropies. | dark matter in 3d |
we study the full-sky distribution of the radio emission from the stimulated decay of axions which are assumed to compose the dark matter in the galaxy. besides the constant extragalactic and cmb components, the decays are stimulated by a galactic radio emission with a spatial distribution that we empirically determine from observations. we compare the diffuse emission to the counterimages of the brightest supernovæ remnants, and take into account the effects of free-free absorption. we show that, if the dark matter halo is described by a cuspy nfw profile, the expected signal from the galactic center is the strongest. interestingly, the emission from the galactic anti-center provides competitive constraints that do not depend on assumptions on the uncertain dark matter density in the inner region. furthermore, the anti-center of the galaxy is the brightest spot if the galactic dark matter density follows a cored profile. the expected signal from stimulated decays of axions of mass $m _{a} \sim 10 ^{-6}$ ev is within reach of the square kilometer array for an axion-photon coupling $g _{a\gamma} \gtrsim (2-3) \times 10 ^{-11}$ gev$^{-1}$. | on the galactic radio signal from stimulated decay of axion dark matter |
dark matter, if represented by a $z_2$-symmetric scalar field, can manifest as both particles and condensates. in this paper, we study the evolution of an oscillating homogeneous condensate of a $z_2$-symmetric scalar field in a thermal plasma in an flrw universe. we focus on the perturbative regime where the oscillation amplitude is sufficiently small so that parametric resonance is inefficient. this perturbative regime necessarily comprises the late stage of the condensate decay and determines its fate. the coupled coarse-grained equations of motion for the condensate, radiation, and spacetime are derived from first principles using nonequilibrium quantum field theory. we obtain analytical expressions for the relevant microscopic quantities that enter the equations of motion and solve the latter numerically. we find that there is always a nonvanishing relic abundance for a $z_2$-symmetric condensate because its decay rate decreases faster than the hubble parameter at late times due to either the amplitude-dependence or the temperature-dependence in the condensate decay rate. consequently, accounting for the condensate contribution to the overall dark matter relic density is essential for $z_2$ scalar singlet dark matter. unlike normal thermal freeze-out for particles, the condensate relic density depends on the initial condition which we take as arbitrary in the present work provided that it falls within the perturbative regime. | fate of homogeneous $z_2$-symmetric scalar condensates |
parity-time ($\mathcal{pt}$) symmetry has become an important concept in the design of synthetic optical materials, with exotic functionalities such as unidirectional transport and non-reciprocal reflection. at exceptional points, this symmetry is spontaneously broken, and solutions transition from those with conserved intensity to exponential growth or decay. here we analyze a quantum-photonic surface formed by a single layer of atoms in an array with light mediating strong cooperative many-body interactions. we show how delocalized collective excitation eigenmodes can exhibit an effective $\mathcal{pt}$ symmetry and non-exponential decay. this effective symmetry is achieved in a passive system without gain by balancing the scattering of a bright mode with the loss from a subradiant dark mode. these modes coalesce at exceptional points, evidenced by the emergence of coherent perfect absorption where coherent incoming light is perfectly absorbed and scattered only incoherently. we also show how $\mathcal{pt}$ symmetry can be generated in total reflection and by balancing scattering and loss between different polarizations of collective modes. | parity-time symmetry and coherent perfect absorption in a cooperative atom response |
an old neutron star (ns) may capture halo dark matter (dm) and get heated up by the deposited kinetic energy, thus behaving like a thermal dm detector with sensitivity to a wide range of dm masses and a variety of dm-quark interactions. near future infrared telescopes will measure ns temperatures down to a few thousand kelvin and probe ns heating by dm capture. we focus on gev-mass dirac fermion dm (which is beyond the reach of current dm direct detection experiments) in scenarios in which the dm capture rate can saturate the geometric limit. for concreteness, we study (1) a model that invokes dark decays of the neutron to explain the neutron lifetime anomaly, and (2) a framework of dm coupled to quarks through a vector current portal. in the neutron dark decay model a ns can have a substantial dm population, so that the dm capture rate can reach the geometric limit through dm self-interactions even if the dm-neutron scattering cross section is tiny. we find ns heating to have greater sensitivity than multipion signatures in large underground detectors for the neutron dark decay model, and sub-gev gamma-ray signatures for the quark vector portal model. | heating neutron stars with gev dark matter |
we explore some experimentally testable predictions of an so(10) axion model which includes two 10-plets of fermions in order to resolve the axion domain wall problem. the axion symmetry can be safely broken after inflation, so that the isocurvature perturbations associated with the axion field are negligibly small. an unbroken gauge z2 symmetry in so(10) ensures the presence of a stable wimp-like dark matter, a linear combination of the electroweak doublets in the fermion 10-plets and an so(10) singlet fermion with mass ∼62.5 gev(1 tev) when it is mostly the singlet (doublet) fermion, that co-exists with axion dark matter. we also discuss gauge coupling unification, proton decay, inflation with non-minimal coupling to gravity and leptogenesis. with the identification of the sm singlet higgs field in the 126 representation of so(10) as inflaton, the magnetic monopoles are inflated away, and we find 0.963 ≲ns≲0.965 and 0.003 ≲r ≲0.036 , where ns and r denote the scalar spectral index and tensor-to-scalar ratio, respectively. these predictions can be tested in future experiments such as cmb-s4. | axions, wimps, proton decay and observable r in so(10) |
a multipole decomposition of a cross section is a useful tool to simplify the analysis of reactions due to their symmetry properties. by using a new approach to decompose antisymmetric tensor-type interactions within the multipole analysis, we introduce a general mathematical formalism for working with tensor couplings. this allows us to present a general tensor nuclear response, which is particularly useful for ongoing β -decay experiments looking for physics beyond the standard model (bsm), as well as other exotic particle scatterings off nuclei, e.g., in dark matter direct detection experiments. using this method, bsm operators identify with the known standard model operators, eliminating the need for calculations of additional matrix elements. we present in detail bsm expressions useful for β -decay experiments and give an exemplary application for 6he β -decay, although the formalism is easily generalizable for calculating other exotic scattering reactions. | multipole decomposition of tensor interactions of fermionic probes with composite particles and bsm signatures in nuclear reactions |
a scalar field phi endowed with a trigonometric potential has been proposed to play the role of dark matter. a deep study of the cosmological evolution of linear perturbations, and its comparison to the cold dark matter (cdm) and fuzzy dark matter (fdm) cases (scalar field with quadratic potential), reveals an enhancement in the amplitude of the mass power spectrum for large wave numbers due to the non-linearity of the axion-like potential. for the first time, we study the scale-dependence on physical quantities such as the growth factor dk, the velocity growth factor fk, and fk σ8. we found that for z<10, all these quantities recover the cdm evolution, whereas for high redshift there is a clear distinction between each model (fdm case, and axion-like potential) depending on the wavenumber k and on the decay parameter of the axion-like potential as well. a semi-analytical halo mass function is also revisited, finding a suppression of the number of low mass halos, as in the fdm case, but with a small increment in the amplitude of the variance and halo mass function due to the non-linearity of the axion-like potential. finally, we present constraints on the axion mass and the axion decay parameter by using data of the planck collaboration 2018 and lyman-α forest. | ultralight dm bosons with an axion-like potential: scale-dependent constraints revisited |
we show that very compact axion mini-clusters can form in models where axion-like-particle (alp) dark matter is produced via the kinetic misalignment mechanism, which is well-motivated in pre-inflationary u(1) symmetry breaking scenarios. this is due to alp fragmentation. we predict denser halos than what has been obtained so far in the literature from standard misalignment in post-inflationary u(1) breaking scenarios or from large misalignment. the main reason is that adiabatic fluctuations are significant at early times, therefore, even if amplification from parametric resonance effects is moderate, the final size of alp fluctuations is larger in kinetic misalignment. we compare halo mass functions and halo spectra obtained in kinetic misalignment, large misalignment and standard misalignment respectively. our analysis does not depend on the specific model realization of the kinetic misalignment mechanism. we present our results generally as a function of the alp mass and the alp decay constant only. we show that a sizable region of this alp parameter space can be tested by future experiments that probe small-scale structures. | alp dark matter mini-clusters from kinetic fragmentation |
a search for dark matter particles is performed by looking for events with large transverse momentum imbalance and a recoiling higgs boson decaying to either a pair of photons or a pair of $\tau$ leptons. the search is based on proton-proton collision data at a center-of-mass energy of 13 tev collected at the cern lhc in 2016 and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. no significant excess over the expected standard model background is observed. upper limits at 95% confidence level are presented for the product of the production cross section and branching fraction in the context of two benchmark simplified models. for the z'-two-higgs-doublet model (where z' is a new massive boson mediator) with an intermediate heavy pseudoscalar particle of mass $m_\mathrm{a} =$ 300 gev and $m_\mathrm{dm} =$ 100 gev, z' masses from 550 gev up to 1265 gev are excluded. for a baryonic z' model, with $m_\mathrm{dm} =$ 1 gev, z' masses up to 615 gev are excluded. results are also presented for the spin-independent cross section for the dark matter-nucleon interaction as a function of the mass of the dark matter particle. this is the first search for dark matter particles produced in association with a higgs boson decaying to two $\tau$ leptons. | search for dark matter produced in association with a higgs boson decaying to $\\gamma\\gamma$ or $\\tau^+\\tau^-$ at $\\sqrt{s} =$ 13 tev |
we report here methods and techniques for creating an improved model that reproduces the scintillation and ionization response of a dual-phase liquid and gaseous xenon time projection chamber. starting with the recent release of the noble element simulation technique (nest v2.0), electronic recoil data from the β decays of 3h and 14c in the large underground xenon (lux) detector were used to tune the model, in addition to external data sets that allow for extrapolation beyond the lux data-taking conditions. this paper also presents techniques used for modeling complicated temporal and spatial detector pathologies that can adversely affect data using a simplified model framework. the methods outlined in this report show an example of the robust applications possible with nest v2.0 framework and how it can be modified to produce a final, detector-specific, electronic recoil model. this example provides the final model for lux and detector parameters that will used in the new analysis package, the lux legacy analysis monte carlo application (llama), for accurate reproduction of the lux data. as accurate background reproduction is crucial for the success of rare-event searches, such as dark matter direct detection experiments, the techniques outlined here can be used in other single-phase and dual-phase xenon detectors to assist with accurate er background reproduction. | improved modeling of β electronic recoils in liquid xenon using lux calibration data |
in this paper we analyze a simple scenario in which dark matter (dm) consists of free fermions with mass mf. we assume that on galactic scales these fermions are capable of forming a degenerate fermi gas, in which stability against gravitational collapse is ensured by the pauli exclusion principle. the mass density of the resulting con figuration is governed by a non-relativistic lane-emden equation, thus leading to a universal cored profile that depends only on one free parameter in addition to mf. after reviewing the basic formalism, we test this scenario against experimental data describing the velocity dispersion of the eight classical dwarf spheroidal galaxies of the milky way. we find that, despite its extreme simplicity, the model exhibits a good fit to the data and realistic predictions for the size of dm halos providing that mf≃ 200 ev. furthermore, we show that in this setup larger galaxies correspond to the non-degenerate limit of the gas. we propose a concrete realization of this model in which dm is produced non-thermally via inflaton decay. we show that imposing the correct relic abundance and the bound on the free-streaming length constrains the inflation model in terms of inflaton mass, its branching ratio into dm and the reheating temperature. | dwarf spheroidal galaxies as degenerate gas of free fermions |
we propose a simple model of dark matter and c p violation and consider the associated triple and quadruple productions of 125 gev higgs bosons at the large hadron collider (lhc). in the model, the dark matter is a vectorlike dark fermion (χ ¯ ,χ ) interacting with the standard model only through a complex messenger scalar s which is an electroweak singlet. new sources of c p violation reside in the most general scalar potential involving the doublet h and the singlet s , as well as in the dark yukawa coupling between s and (χ ¯,χ ). we study current experimental constraints from higgs measurements, searches for new scalars at the lhc, precision electroweak measurements, edm measurements, dark matter relic density, as well as direct and indirect detections of dark matter. a smoking-gun signature of c p violation could come from the higgs-to-higgs decays, h3→h2h1 , where h3/h2/h1 are the heaviest scalar, second heaviest scalar and the sm-like 125-gev higgs, respectively. taking into account other higgs-to-higgs decays, such as h3→2 h2 and h3/h2→2 h1, then gives rise to novel 3 h1 and 4 h1 final states, which have yet to be searched for experimentally. we present four benchmarks and show the event rates for 3 h1 and 4 h1 final states could be as large as o (10 ) fb and o (1 ) fb , respectively, at the 14-tev lhc. this work opens up a new frontier of searching for triple and quadruple higgs bosons at a high energy collider. | simple model of dark matter and c p violation |
we analyse the dynamical properties of three-dimensional solitary waves in cylindrically trapped bose-einstein condensates. families of solitary waves bifurcate from the planar dark soliton and include the solitonic vortex, the vortex ring and more complex structures of intersecting vortex lines known collectively as chladni solitons. the particle-like dynamics of these guided solitary waves provides potentially profitable features for their implementation in atomtronic circuits, and play a key role in the generation of metastable loop currents. based on the time-dependent gross-pitaevskii equation we calculate the dispersion relations of moving solitary waves and their modes of dynamical instability. the dispersion relations reveal a complex crossing and bifurcation scenario. for stationary structures we find that for μ /{\hslash }{ω }\perp \gt 2.65 the solitonic vortex is the only stable solitary wave. more complex chladni solitons still have weaker instabilities than planar dark solitons and may be seen as transient structures in experiments. fully time-dependent simulations illustrate typical decay scenarios, which may result in the generation of multiple separated solitonic vortices. | stability and dispersion relations of three-dimensional solitary waves in trapped bose-einstein condensates |
a search for dark matter produced in association with top quarks in proton-proton collisions at a center-of-mass energy of 13 tev is presented. the data set used corresponds to an integrated luminosity of 35.9 fb$^{-1}$ recorded with the cms detector at the lhc. whereas previous searches for neutral scalar or pseudoscalar mediators considered dark matter production in association with a top quark pair only, this analysis also includes production modes with a single top quark. the results are derived from the combination of multiple selection categories that are defined to target either the single top quark or the top quark pair signature. no significant deviations with respect to the standard model predictions are observed. the results are interpreted in the context of a simplified model in which a scalar or pseudoscalar mediator particle couples to a top quark and subsequently decays into dark matter particles. scalar and pseudoscalar mediator particles with masses below 290 and 300 gev, respectively, are excluded at 95% confidence level, assuming a dark matter particle mass of 1 gev and mediator couplings to fermions and dark matter particles equal to unity. | search for dark matter produced in association with a single top quark or a top quark pair in proton-proton collisions at $\\sqrt{s} =$ 13 tev |
we present a new paradigm, asymptotic grand unification, where the gauge couplings run to a unique fixed point in the ultraviolet, without supersymmetry and without quantitative unification at any given scale. we introduce a minimal model based on an su(5) gauge theory in a compact s1/(z2×z2') orbifold. by construction, fermions are embedded in different su(5) bulk fields. as a consequence, the baryon number is conserved, thus preventing proton decay, and the lightest kaluza-klein tier consists of new states that cannot decay into standard model ones. we show that the yukawa couplings can be either in the bulk or localized and run to an asymptotically free fixed point in the uv. the lightest massive state can play the role of dark matter, produced via baryogenesis, for a kaluza-klein mass of about 2.4 tev. | minimal su(5) asymptotic grand unification |
a measurement of hafnium foil using a modified ultra-low-background high purity detector with optimized sample-to-detector geometry was performed at laboratori nazionale del gran sasso. radiopurity of the stock hf foil was studied in detail, in addition to an analysis of data collected over 310 days to search for rare processes that can occur in natural hf isotopes. firstly, limits on alpha decays of all natural hf isotopes to the first excited state of the daughter nuclides were established in the range of 1016-1018a (90% c.l.). secondly, a search for modes of double electron capture and electron capture with positron emission in 174hf was performed, yielding half-life limits 1016-1018a (90% c.l.). lastly, novel dark matter-induced nuclear excitations in hafnium isotopes were investigated. for dark matter with 1 tev/c2 mass, leading limits on the inelastic dark matter-nucleon cross section are set for mass splittings in the range 428 kev <δm < 473 kev in the adopted model framework. | a search for rare and induced nuclear decays in hafnium |
we explore beta decays in a dark background field, which could be formed by dark matter, dark energy or a fifth force potential. in such scenarios, the neutrino's dispersion relation will be modified by its collective interaction with the dark field, which can have interesting consequences in experiments using tritium beta decays to determine the absolute neutrino mass. among the most general interaction forms, the (pseudo)scalar and (axial-)vector ones are found to have interesting effects on the spectrum of beta decays. in particular, the vector and axial-vector potentials can induce distinct signatures by shifting the overall electron energy scale, possibly beyond the usually defined endpoint. the scalar and pseudoscalar potentials are able to mimic a neutrino mass beyond the cosmological bounds. we have placed stringent constraints on the dark potentials based on the available experimental data of katrin. the sensitivity of future katrin runs is also discussed. | tritium beta decay with modified neutrino dispersion relations: katrin in the dark sea |
if the early universe is dominated by an energy density which evolves other than radiation-like the normal hubble-temperature relation hpropto t2 is broken and dark matter relic density calculations in this era can be significantly different. we first highlight that with a population of states phi sourcing an initial expansion rate of the form hpropto t2+n/2, for n>=-4, during the period of appreciable phi decays the evolution transitions to hpropto t4. the decays of phi imply a source of entropy production in the thermal bath which alters the boltzmann equations and impacts the dark matter relic abundance. we show that the form of the initial expansion rate leaves a lasting imprint on relic densities established while hpropto t4 since the value of the exponent n changes the temperature evolution of the thermal bath. in particular, a dark matter relic density set via freeze-in or non-thermal production is highly sensitive to the temperature dependance of the initial expansion rate. this work generalises earlier studies which assumed initial expansion rates due to matter or kination domination. | establishing the dark matter relic density in an era of particle decays |
we explore the suggestion that the neutron lifetime puzzle might be resolved by neutrons decaying into dark matter through the process, n → χ χ χ, with χ having a mass one-third of the neutron. in particular, we examine the consequences of such a decay mode for the properties of neutron stars. unlike an earlier suggested decay mode, in order to satisfy the constraints on neutron star mass and tidal deformability, there is no need for a strong repulsive force between the dark matter particles. this study suggests the possibility of having hot dark matter at the core of the neutron star and presents a possible mechanism of dark matter cooling, and examines the possible signal of neutrons decaying in this way inside the neutron star right after its birth. | novel neutron decay mode inside neutron stars |
we propose a cosmological scenario involving a scalar field, varphi, that is a source of dark matter as well as of dark energy. besides varphi, the lagrangian of the field theory envisaged in our scenario contains a second field χ, for simplicity assumed to be a scalar, too. for fixed values of χ, the potential term decays exponentially at large positive values of varphi. while varphi is not coupled to standard model fields, χ is assumed to be coupled to them, and the green functions of χ depend on the cosmological redshift in the expanding universe. we assume that the term in the lagrangian coupling χ to varphi is such that, at redshifts z larger than some critical redshift zc, varphi is trapped near varphi=0, and oscillations of varphi about varphi=0 describing massive scalar particles give rise to dark matter. at redshifts below zc, the field varphi is no longer trapped near the origin and starts to "roll" towards large field values. a homogenous component of varphi emerges that acts as dark energy. within over-dense regions, such as galaxies and galaxy clusters, the redshifting of χ stops, and varphi therefore remains trapped near varphi=0 as long as zc is smaller than the redshift when structures on galactic scales decouple from the hubble flow. thus, at the present time, varphi describes both dark energy and dark matter. | new scalar field quartessence |
we propose a pseudo-nambu-goldstone boson (pngb) dark matter (dm) model based on an additional non-abelian gauge symmetry s u (2 )d. the gauge symmetry s u (2 )d is spontaneously broken to a global custodial symmetry u (1 )v via the nonvanishing vacuum expectation values of s u (2 )d doublet and triplet scalar fields. due to the exact global symmetry u (1 )v, the lightest u (1 )v charged particle becomes stable. we assume that the lightest charged particle in the model is the charged complex pngb, which we regard as dm. it avoids the strong constraints from current dm direct detection experiments due to the property of ngb. we find that the measured energy density of dm can be reproduced when the dm mass is larger than the half of the higgs mass, where the lower limit generally comes from the constraint of dm invisible decay and the upper limit from dm direct detection experiments depends on the model parameters. | pseudo-nambu-goldstone dark matter from non-abelian gauge symmetry |
we study mono-w signals of dark matter (dm) production at the lhc, in the context of gauge invariant renormalizable models. we analyze two simplified models, one involving an s-channel z' mediator and the other a t-channel colored scalar mediator, and consider examples in which the dm-quark couplings are either isospin conserving or isospin violating after electroweak symmetry breaking. while previous work on mono-w signals have focused on isospin violating efts, obtaining very strong limits, we find that isospin violating effects are small once such physics is embedded into a gauge invariant simplified model. we thus find that the 8 tev mono-w results are much less constraining than those arising from mono-jet searches. considering both the leptonic (mono-lepton) and hadronic (mono fat jet) decays of the w, we determine the 14 tev lhc reach of the mono-w searches with 3000 fb-1 of data. while a mono-w signal would provide an important complement to a mono-jet discovery channel, existing constraints on these models imply it will be a challenging signal to observe at the 14 tev lhc. | mono-w dark matter signals at the lhc: simplified model analysis |
we study a class of realizations of the next-to-minimal supersymmetric standard model that is motivated by dark matter and higgs data, and in which the lightest pseudoscalar higgs boson mass is smaller than twice the bottom quark mass and greater than twice the tau lepton mass. in such scenarios, the lightest pseudoscalar higgs boson can be copiously produced at the lhc from the decay of heavier superpartners and will dominantly further decay into a pair of tau leptons that is generally boosted. we make use of a boosted object tagging technique designed to tag such a ditau jet, and estimate the sensitivity of the lhc to the considered supersymmetric scenarios with 20 to 50 fb-1 of proton-proton collisions at a center-of-mass energy of 13 tev. | investigating light nmssm pseudoscalar states with boosted ditau tagging |
we study the effect of the early kinetic decoupling in a model of fermionic dark matter (dm) that interacts with the standard model particles only by exchanging the higgs boson. there are two dm-higgs couplings, namely c p -conserving and c p -violating couplings. if the mass of the dm is slightly below half of the higgs boson mass, then the couplings are suppressed to obtain the measured value of the dm energy density by the freeze-out mechanism. in addition, the scattering processes of dm off particles in the thermal bath are suppressed by the small momentum transfer if the c p -violating dm-higgs coupling is larger than the c p -conserving one. due to the suppression, the temperature of the dm can differ from the temperature of the thermal bath. by solving coupled equations for the number density and temperature of the dm, we calculate the dm-higgs couplings that reproduce the right amount of the dm relic abundance. we find that the couplings have to be larger than the one obtained without taking into account the difference in the temperatures. a consequence of the enhancement of the dm-higgs couplings is the enhancement of the higgs invisible decay branching ratio. the enhancement is testable at current and future collider experiments. | effect of the early kinetic decoupling in a fermionic dark matter model |
we study cosmology with running dark energy. the energy density of dark energy is obtained from the quantum process of transition from the false vacuum state to the true vacuum state. we use the breit-wigner energy distribution function to model the quantum unstable systems and obtain the energy density of the dark energy parametrization ρ _ {de}(t). we also use krauss and dent's idea linking properties of the quantum mechanical decay of unstable states with the properties of the observed universe. in the cosmological model with this parametrization there is an energy transfer between dark matter and dark energy. the intensity of this process, measured by a parameter α , distinguishes two scenarios. as the universe starts from the false vacuum state, for the small value of α (0<α <0.4) it goes through an intermediate oscillatory (quantum) regime of the density of dark energy, while for α > 0.4 the density of the dark energy jumps down. in both cases the present value of the density of dark energy is reached. from a statistical analysis we find this model to be in good agreement with the astronomical data and practically indistinguishable from the λ cdm model. | cosmological implications of the transition from the false vacuum to the true vacuum state |
we investigate dynamical self-friction, the process by which material that is stripped from a subhalo torques its remaining bound remnant, which causes it to lose orbital angular momentum. by running idealized simulations of a subhalo orbiting within an analytical host halo potential, we isolate the effect of self-friction from traditional dynamical friction due to the host halo. while at some points in a subhalo's orbit the torque of the stripped material can boost the orbital angular momentum of the remnant, the net effect over the long term is orbital decay regardless of the initial orbital parameters or subhalo mass. in order to quantify the strength of self-friction, we run a suite of simulations spanning typical host-to-subhalo mass ratios and orbital parameters. we find that the time-scale for self-friction, defined as the exponential decay time of the subhalo's orbital angular momentum, scales with mass ratio and orbital circularity similar to standard dynamical friction. the decay time due to self-friction is roughly an order of magnitude longer, suggesting that self-friction only contributes at the 10 per cent level. however, along more radial orbits, self-friction can occasionally dominate over dynamical friction close to pericentric passage, where mass stripping is intense. this is also the epoch at which the self-friction torque undergoes large and rapid changes in both magnitude and direction, indicating that self-friction is an important process to consider when modelling pericentric passages of subhaloes and their associated satellite galaxies. | dynamical self-friction: how mass loss slows you down |
we study a simple model of vector dark matter that couples to standard model particles via magnetic dipole interactions. in this scenario, the cosmological abundance arises through the freeze-in mechanism and depends on the dipole coupling, the vector mass, and the reheat temperature. to ensure cosmological metastability, the vector must be lighter than the fermions to which it couples, but rare decays can still produce observable 3 γ final states; two-body decays can also occur at one loop with additional weak suppression, but are subdominant if the vector couples mainly to light fermions. for sufficiently heavy vectors, induced kinetic mixing with the photon can also yield additional two-body decays to lighter fermions and predict indirect detection signals through final-state radiation. we explore the implications of couplings to various flavors of visible particles and emphasize leptophilic dipoles involving electrons, muons, and taus, which offer the most promising indirect detection signatures through 3 γ , e+e-γ , and μ+μ-γ decay channels. we also present constraints from current and past telescopes, and sensitivity projections for future missions including e-astrogam and amego. | freezing in vector dark matter through magnetic dipole interactions |
1. introduction; 2. relativistic notation, lagrangians, and interactions; 3. gauge invariance; 4. non-abelian gauge theories; 5. dirac notation for spin; 6. the standard model lagrangian; 7. the electroweak theory and quantum chromodynamics; 8. masses and the higgs mechanism; 9. cross sections, decay widths, and lifetimes: w and z decays; 10. production and properties of w± and zᴼ; 11. measurement of electroweak and qcd parameters: the muon lifetime; 12. accelerators - present and future; 13. experiments and detectors; 14. low energy and non-accelerator experiments; 15. observation of the higgs boson at the cern lhc: is it the higgs boson?; 16. colliders and tests of the standard model: particles are pointlike; 17. quarks and gluons, confinement and jets; 18. hadrons, heavy quarks, and strong isospin invariance; 19. coupling strengths depend on momentum transfer and on virtual particles; 20. quark (and lepton) mixing angles; 21. cp violation; 22. overview of physics beyond the standard model; 23. grand unification; 24. neutrino masses; 25. dark matter; 26. supersymmetry. | modern elementary particle physics |
in this paper, we investigate the behavior of cosmologies in homogeneous and isotropic background with a barotropic fluid. we solve the continuity equation and study several aspects of model including behavior of cosmological quantities like hubble parameter, deceleration parameter, equation of state parameter along with statefinder diagnostic and validity of energy conditions. the γ′− γ plane is checked for identification of thawing and freezing regions. we derive the lagrangian formulation with standard and non-standard kinetic terms for barotropic fluid model. it is demonstrated that the model possesses periodic potential in its lagrangian description with standard kinetic terms. using dynamical system analysis, we find the stability of solutions, too. we further explore the thermodynamic aspects at apparent horizon by investigating the validity of generalized second law of thermodynamics with equilibrium description. the model exhibits complete cosmological scenario for different values of model parameters and the inflationary scenario decays smoothly into radiation-dominated phase during its evolution. the model approaches to λ cold dark matter model during late times of its evolution. | lagrangian formulation and implications of barotropic fluid cosmologies |
the distribution and fate of coloured dissolved organic matter (cdom) in the epipelagic eastern north atlantic was investigated during a cruise in the summer 2009 by combining field observations and culture experiments. dissolved organic carbon (doc) and nitrogen (don), the absorption spectra of cdom and the fluorescence intensity of proteins (ex/em 280/320 nm; f(280/320)) and marine humic-like substances (f(320/410)) were measured in the upper 200 m. doc and don showed higher concentrations in the top 20 m than below, and doc increased southwards, while don decreased. f(280/320) and f(320/410) showed maxima near the deep chlorophyll maximum (at about 50 m), suggesting that these fluorophores were linked to phytoplankton production and the metabolism of the associated microbial community. the coloured and fluorescent fractions of dom showed low levels south of the azores front, at about 35 °n, likely due to the accumulated photobleaching of the waters transported eastwards by the azores current into the study area (at 20°w). twelve culture experiments were also conducted with surface water (5 m) to assess the impact of microbial degradation processes on the bulk, coloured and fluorescent fractions of dom. after 72 h of incubation in the darkness, 14±9% (average±sd) of the initial don was consumed at an average rate of 0.24±0.14 μmol l-1 d-1 and the protein-like fluorescence decayed by 29±9% at a net rate of 0.06±0.03 qsu d-1. these rates were significantly lower south of the azores front, suggesting that dom in this region was of a more recalcitrant nature. conversely, the marine humic-like fluorescence increased at a net rate of 0.013±0.003 qsu d-1. the close linear relationship of don uptake with f(280/320) consumption (r2= 0.91, p <0.0001, n=12) and f(320/410) production (r2= 0.52, p <0.008, n=12) that we found during these incubation experiments suggest that the protein-like fluorescence can be used as a proxy for the dynamics of the labile don pool and that marine humic-like materials can be produced as a by-product of microbial dom degradation. | production and degradation of fluorescent dissolved organic matter in surface waters of the eastern north atlantic ocean |
in supersymmetric axion models, if the gravitino or axino is the lightest susy particle (lsp), the other is often the next-to-lsp (nlsp). we investigate the cosmology of such a scenario and point out that the lifetime of the nlsp naturally becomes comparable to the present age of the universe in a viable parameter region. this is a well-motivated example of the so-called decaying dark matter model, which is recently considered as an extension of the λcdm model to relax some cosmological tensions. | gravitino/axino as decaying dark matter and cosmological tensions |
we discuss the possibility to predict the qcd axion mass in the context of grand unified theories. we investigate the implementation of the dfsz mechanism in the context of renormalizable su(5) theories. in the simplest theory, the axion mass can be predicted with good precision in the range $m_a = (2-16)$ nev, and there is a strong correlation between the predictions for the axion mass and proton decay rates. in this context, we predict an upper bound for the proton decay channels with antineutrinos, $\tau(p\to k^+ \bar{\nu}) \lesssim 4 \times 10^{37} \text{ yr}$ and $\tau(p \to \pi^+ \bar{\nu}) \lesssim 2 \times 10^{36}\text{ yr}$. this theory can be considered as the minimal realistic grand unified theory with the dfsz mechanism and it can be fully tested by proton decay and axion experiments. | axion dark matter, proton decay and unification |
the recent discovery of the unidentified emission line at 3.5 kev in galaxies and clusters has attracted great interest from the community. as the origin of the line remains uncertain, we study the surface brightness distribution of the line in the perseus cluster since that information can be used to identify its origin. we examine the flux distribution of the 3.5 kev line in the deep suzaku observations of the perseus cluster in detail. the 3.5 kev line is observed in three concentric annuli in the central observations, although the observations of the outskirts of the cluster did not reveal such a signal. we establish that these detections and the upper limits from the non-detections are consistent with a dark matter decay origin. however, absence of positive detection in the outskirts is also consistent with some unknown astrophysical origin of the line in the dense gas of the perseus core, as well as with a dark matter origin with a steeper dependence on mass than the dark matter decay. we also comment on several recently published analyses of the 3.5 kev line. | radial profile of the 3.5 kev line out to r200 in the perseus cluster |
narrow-band invisibility in an otherwise opaque medium has been achieved by electromagnetically induced transparency (eit) in atomic systems. the quantum eit behavior can be classically mimicked by specially engineered metamaterials via carefully controlled interference with a "dark mode." however, the narrow transparency window limits the potential applications that require a tunable wideband transparent performance. here, we present a macroscopic quantum superconducting metamaterial with manipulative self-induced broadband transparency due to a qualitatively novel nonlinear mechanism that is different from conventional eit or its classical analogs. a near-complete disappearance of resonant absorption under a range of applied rf flux is observed experimentally and explained theoretically. the transparency comes from the intrinsic bistability of the meta-atoms and can be tuned on and off easily by altering rf and dc magnetic fields, temperature, and history. hysteretic in situ 100% tunability of transparency paves the way for autocloaking metamaterials, intensity-dependent filters, and fast-tunable power limiters. | tunable broadband transparency of macroscopic quantum superconducting metamaterials |
we examine a scenario for freeze-in production of dark matter, which occurs due to the large thermal correction to the mass of a decaying mediator particle present in the thermal bath of the early universe. we show that the decays, which are kinematically forbidden otherwise, can open up at very high temperatures and dominate the dark matter production. we explore such forbidden production of dark matter in the minimal u(1) b-lmodel, comparing dark matter phenomenology in the context of forbidden frozen-in with the standard picture. | freeze-in dark matter through forbidden channel in u(1) b-l |
a renormalizable uv model for axionlike particles or hidden photons, which may explain the dark matter, usually involves a dark higgs field, which is a singlet under the standard model (sm) gauge group. the dark sector can couple to the sm particles via the portal coupling between the sm-like higgs and dark higgs fields. through this coupling, the dark sector particles can be produced in either the early universe or the collider experiments. interestingly, not only the sm-like higgs boson can decay into the light dark bosons, but also a light dark higgs boson may be produced and decay into the dark bosons in a collider. in this paper, we perform the first collider search for invisible decays by taking both the higgs bosons into account. we use a multivariate technique to best discriminate the signal from the background. we find that a large parameter region can be probed at the international linear collider operating at the center-of-mass energy of 250 gev. in particular, even when the sm-like higgs invisible decay is a few orders of magnitude below the planned sensitivity reaches of the international linear collider and the high luminosity lhc, the scenario can be probed by the invisible decay of the dark higgs boson produced via a similar diagram. measuring the dark higgs boson decay into the dark sector will be a smoking gun signal of the light dark sector. a similar search of the dark sector would be expected in, e.g., the cool copper collider, the circular electron positron collider, the compact linear collider, and the future circular electron-positron collider. | probing a light dark sector at future lepton colliders via invisible decays of the sm-like and dark higgs bosons |
we derive in detail the orbital period loss of a compact binary system in presence of a fifth force and radiation of ultralight particles for a general eccentric keplerian orbit. we obtain constraints on fifth force strength $\alpha\lesssim 1.11\times 10^{-3}$ from the orbital period decay of compact binary systems. we derive constraints on the gauge coupling of ultralight scalar $(g_s\lesssim 3.06\times 10^{-20})$ and vector $(g_v\lesssim 2.29\times 10^{-20})$ particles from orbital period loss and the constraints get stronger in presence of a fifth force $(\alpha=0.9)$. in addition, we also obtain constraints on the axion decay constant $(7.94\times 10^{10}~\rm{gev}\lesssim f_a\lesssim 3.16\times 10^{17}~\rm{gev}, \alpha=0.9)$ if the orbital period decays due to the combined effects of axionic fifth force and axion radiation. we also achieve constraints on the strengths of the fifth force $(\alpha\lesssim 0.025)$ and radiation $(\beta\lesssim 10^{-3})$ from gw170817. the constraints on new force parameters depend on the choice of the initial eccentricity which we include in our analysis $(\epsilon_0=10^{-6}, 0.1)$. we do the model independent estimate of the capture of dark matter mass fraction by a binary system. lastly, we obtain constraints on fifth force strength due to brans-dicke mediated scalar between two compact stars in a binary system $(\omega_{\rm{bd}}>266)$ and from the nordtvedt effect $(\omega_{\rm{bd}}>75858)$. the bound on brans-dicke coupling gets stronger if one includes the effect of eccentricity. our constraints can be generalized to any alternative theories of gravity and will be within the reach of second and third generation gravitational wave detectors. | listening to dark sirens from gravitational waves:\\it{combined effects of fifth force, ultralight particle radiation, and eccentricity} |
the physics of the electronic excitation in semiconductors induced by sub-gev dark matter (dm) have been extensively discussed in literature, under the framework of the standard plane wave (pw) and pseudopotential calculation scheme. in this paper, we investigate the implication of the all-electron (ae) reconstruction on estimation of the dm-induced electronic transition event rates. as a benchmark study, we first calculate the wavefunctions in silicon and germanium bulk crystals based on both the ae and pseudo (ps) schemes within the projector augmented wave (paw) framework, and then make comparisons between the calculated excitation event rates obtained from these two approaches. it turns out that in process where large momentum transfer is kinetically allowed, the two calculated event rates can differ by a factor of a few. such discrepancies are found to stem from the high-momentum components neglected in the ps scheme. it is thus implied that the correction from the ae wavefunction in the core region is necessary for an accurate estimate of the dm-induced transition event rate in semiconductors. | the wavefunction reconstruction effects in calculation of dm-induced electronic transition in semiconductor targets |
a search for new physics in events with a z boson produced in association with large missing transverse momentum at the lhc is presented. the search is based on the 2016 data sample of proton-proton collisions recorded with the cms experiment at √{s} = 13 {tev} , corresponding to an integrated luminosity of 35.9 {fb}^{-1}. the results of this search are interpreted in terms of a simplified model of dark matter production via spin-0 or spin-1 mediators, a scenario with a standard-model-like higgs boson produced in association with the z boson and decaying invisibly, a model of unparticle production, and a model with large extra spatial dimensions. no significant deviations from the background expectations are found, and limits are set on relevant model parameters, significantly extending the results previously achieved in this channel. | search for new physics in events with a leptonically decaying z boson and a large transverse momentum imbalance in proton-proton collisions at √{s} = 13 {tev} |
the formation and decay of dark matter (dm) bound states deplete the thermal relic density during the chemical decoupling process, allowing for larger dm masses. while so far the bound state formation (bsf) has been described via the emission of an on-shell mediator, we point out that this particular process does not have to be the dominant one in general. if the mediator is coupled in a direct way to any relativistic species present in the early universe, we demonstrate that bsf can much more efficiently occur through particle scattering. consequently, dm can be heavier than previously expected. | rapid bound state formation of dark matter in the early universe |
a search for dijet resonances in events with at least one isolated charged lepon is performed using 139 fb-1 of √{s } = 13 tev proton-proton collision data recorded by the atlas detector at the lhc. the dijet invariant-mass (mjj) distribution constructed from events with at least one isolated electron or muon is searched in the region 0.22 < mjj< 6.3 tev for excesses above a smoothly falling background from standard model processes. triggering based on the presence of a lepton in the event reduces limitations imposed by minimum transverse momentum thresholds for triggering on jets. this approach allows smaller dijet invariant masses to be probed than in inclusive dijet searches, targeting a variety of new-physics models, for example ones in which a new state is produced in association with a leptonically decaying w or z boson. no statistically significant deviation from the standard model background hypothesis is found. limits on contributions from generic gaussian signals with widths ranging from that determined by the detector resolution up to 15% of the resonance mass are obtained for dijet invariant masses ranging from 0.25 tev to 6 tev. limits are set also in the context of several scenarios beyond the standard model, such as the sequential standard model, a technicolor model, a charged higgs boson model and a simplified dark matter model. | search for dijet resonances in events with an isolated charged lepton using √{s } = 13 tev proton-proton collision data collected by the atlas detector |
we consider dark matter consisting of long-living particles with masses 107 gev ≲ m ≲1016 gev decaying through hadronic channel as a source of high-energy neutrino. using recent data on high-energy neutrino from icecube and pierre auger experiments, we derive the upper-limits on neutrino flux from dark matter decay and constraints on dark matter parameter space. for the dark matter masses of order 108 gev the constraints derived are slightly stronger than those obtained for the same dark matter model using the highenergy gamma-ray limits. | hadronically decaying heavy dark matter and high-energy neutrino limits |
a model of high scale inflation is presented where the radial part of the peccei-quinn (pq) field with a non-minimal coupling to gravity plays the role of the inflaton, and the qcd axion is the dark matter. a quantum fluctuation of o (h /2 π ) in the axion field will result in a smaller angular fluctuation if the pq field is sitting at a larger radius during inflation than in the vacuum. this changes the effective axion decay constant, fa, during inflation and dramatically reduces the production of isocurvature modes. this mechanism opens up a new window in parameter space where an axion decay constant in the range 1 012 gev ≲fa≲1 015 gev is compatible with observably large r . the exact range allowed for fa depends on the efficiency of reheating. this model also predicts a minimum possible value of r =1 0-3. the new window can be explored by a measurement of r possible with spider and the proposed casper experiment search for high fa axions. | unifying inflation and dark matter with the peccei-quinn field: observable axions and observable tensors |
the search for a dark photon produced at e+e- colliders which subsequently decays into inelastic dark matter particles, is discussed. the heavier dark matter decays into a pair of visible charged particles and a lighter dark matter particle after traveling some distance. the visible decay products can be recorded by a dark matter detector made of emulsions and gas detectors, placed near the main e+e- detector. this setup can not only explore new parameter regions not reached before, but also re-open some regions thought to be excluded by previous experimental data. the physics potential for such a detector around besiii and belle ii is presented. | search for dark photon and dark matter signatures around electron-positron colliders |
the field of particle physics is living very exciting times with a plethora of experiments looking for new physics in complementary ways. this has made increasingly necessary to obtain precise predictions in new physics models in order to be ready for a discovery that might be just around the corner. however, analyzing new models and studying their phenomenology can be really challenging. computing mass matrices, interaction vertices and decay rates is already a tremendous task. in addition, obtaining predictions for the dark matter relic density and its detection prospects, computing flavor observables or estimating the lhc reach in certain collider signals constitutes quite a technical work due to the precision level that is currently required. for this reason, computer tools such as sarah, micromegas, madgraph, spheno or flavorkit have become quite popular, and many physicists use them on a daily basis. in this course we will learn how to use these computer tools to explore new physics models and get robust numerical predictions to probe them in current and future experiments. | computer tools in particle physics |
the bright scintillation of pure csi operated at liquid-nitrogen temperature makes of this material a promising dark matter and neutrino detector. we present the first measurement of its quenching factor for nuclear recoils. our findings indicate it is indistinguishable from that for sodium-doped csi at room temperature. additional properties such as light yield, afterglow, scintillation decay properties for electron and nuclear recoils, and energy proportionality are studied over the 108-165 k temperature range, confirming the vast potential of this medium for rare-event searches. | response of undoped cryogenic csi to low-energy nuclear recoils |
this paper presents a statistical combination of searches targeting final states with two top quarks and invisible particles, characterised by the presence of zero, one or two leptons, at least one jet originating from a b-quark and missing transverse momentum. the analyses are searches for phenomena beyond the standard model consistent with the direct production of dark matter in pp collisions at the lhc, using 139 fb-1 of data collected with the atlas detector at a centre-of-mass energy of 13 tev. the results are interpreted in terms of simplified dark matter models with a spin-0 scalar or pseudoscalar mediator particle. in addition, the results are interpreted in terms of upper limits on the higgs boson invisible branching ratio, where the higgs boson is produced according to the standard model in association with a pair of top quarks. for scalar (pseudoscalar) dark matter models, with all couplings set to unity, the statistical combination extends the mass range excluded by the best of the individual channels by 50 (25) gev, excluding mediator masses up to 370 gev. in addition, the statistical combination improves the expected coupling exclusion reach by 14% (24%), assuming a scalar (pseudoscalar) mediator mass of 10 gev. an upper limit on the higgs boson invisible branching ratio of 0.38 (0.30-0.09+0.13) is observed (expected) at 95% confidence level. | constraints on spin-0 dark matter mediators and invisible higgs decays using atlas 13 tev pp collision data with two top quarks and missing transverse momentum in the final state |
we study cosmological effects of explicit peccei-quinn breaking on the qcd axion dark matter. we find that the axion abundance decreases or increases significantly depending on the initial position, even for a tiny peccei-quinn breaking that satisfies the experimental bound of the neutron electric dipole measurements. if the axion first starts to oscillate around a wrong vacuum and if it gets trapped there until the false vacuum disappears due to non-perturbative qcd effects, its abundance increases significantly and is independent of the decay constant fa , as first pointed out in ref. [1]. thus, the axion produced by the trapping mechanism can explain dark matter even when the decay constant is close to the lower limit due to stellar cooling arguments. on the other hand, if the axion starts to oscillate about a potential minimum close to the low-energy vacuum, its abundance is significantly reduced because of the adiabatic suppression mechanism. this relaxes the upper limit of the axion window to large values of fa . we also discuss how the axionic isocurvature perturbation is affected by the peccei-quinn breaking term, and show that it can be suppressed in both regimes. in particular, the isocurvature bound on the inflation scale is relaxed by many orders of magnitudes for fa ≳ 1011 gev compared to the conventional scenario. | cosmological effects of peccei-quinn symmetry breaking on qcd axion dark matter |
the inclusion of a period of (effective) matter domination following inflation and prior to the onset of radiation domination has interesting and observable consequences for structure growth. during this early matter-dominated era (emde), the universe was dominated by massive particles, or an oscillating scalar field, that decayed into standard model particles, thus reheating the universe. this decay process could also be the primary source of dark matter. in the absence of fine-tuning between the masses of the parent and daughter particles, both dark matter particles and standard model particles would be produced with relativistic velocities. we investigate the effects of the nonthermal production of dark matter particles with relativistic velocities on the matter power spectrum by determining the resulting velocity distribution function for the dark matter. we find that the vast majority of dark matter particles produced during the emde are still relativistic at reheating, so their free streaming erases the perturbations that grow during the emde. the free streaming of the dark matter particles can also prevent the formation of satellite galaxies around the milky way and the structures observed in the lyman-α forest. for a given reheat temperature, these observations put an upper limit on the velocity of the dark matter particles at their creation. for example, for a reheat temperature of 10 mev, dark matter must be produced with a lorentz factor γ ≲550 . | constraining nonthermal dark matter's impact on the matter power spectrum |
we demonstrate a common origin for high-scale leptogenesis and three-loop neutrino mass generation. specifically we extend the standard model by two real singlet scalars, two singly charged scalars carrying different quantum numbers under certain global symmetry and two or more singlet fermions with majorana masses. this global symmetry is only allowed to be softly or spontaneously broken. our model also respects an exactly conserved z 2 discrete symmetry. through the real scalar decays and then the charged scalar decays, we can obtain a lepton asymmetry stored in the standard model leptons. this lepton asymmetry can be partially converted to a baryon asymmetry by the sphaleron processes. the interactions for this leptogenesis can also result in a three-loop diagram to generate the neutrino masses. the lightest singlet fermion can keep stable to serve as a dark matter particle. | high-scale leptogenesis with three-loop neutrino mass generation and dark matter |
the high energy events observed at the icecube neutrino observatory have triggered many investigations interpreting the highly energetic neutrinos detected as decay products of heavy unstable dark matter particles. however, while very detailed treatments of the icecube phenomenology exist, only a few references focus on the (non-trivial) dark matter production part—and all of those rely on relatively complicated new models which are not always testable directly. we instead investigate two of the most minimal scenarios possible, where the operator responsible for the icecube events is directly involved in dark matter production. we show that the simplest (four-dimensional) operator is not powerful enough to accommodate all constraints. a more non-minimal setting (at mass dimension six), however, can do both fitting all the data and also allowing for a comparatively small parameter space only, parts of which can be in reach of future observations. we conclude that minimalistic approaches can be enough to explain all data required, while complicated new physics seems not to be required by icecube. | a consistent theory of decaying dark matter connecting icecube to the sesame street |
a search for dark matter is conducted in events with large missing transverse momentum and a hadronically decaying, lorentz-boosted top quark. this study is performed using proton-proton collisions at a center-of-mass energy of 13 tev, in data recorded by the cms detector in 2016 at the lhc, corresponding to an integrated luminosity of 36 fb$^{-1}$. new substructure techniques, including the novel use of energy correlation functions, are utilized to identify the decay products of the top quark. with no significant deviations observed from predictions of the standard model, limits are placed on the production of new heavy bosons coupling to dark matter particles. for a scenario with purely vector-like or purely axial-vector-like flavor changing neutral currents, mediator masses between 0.20 and 1.75 tev are excluded at 95% confidence level, given a sufficiently small dark matter mass. scalar resonances decaying into a top quark and a dark matter fermion are excluded for masses below 3.4 tev, assuming a dark matter mass of 100 gev. | search for dark matter in events with energetic, hadronically decaying top quarks and missing transverse momentum at $\\sqrt{s}=$ 13 tev |
this article reports on a search for dark matter pair production in association with a higgs boson decaying to a pair of bottom quarks, using data from $20.3 fb^{-1}$ of $pp$ collisions at a center-of-mass energy of 8 tev collected by the atlas detector at the lhc. the decay of the higgs boson is reconstructed as a high-momentum $b\bar{b}$ system with either a pair of small-radius jets, or a single large-radius jet with substructure. the observed data are found to be consistent with the expected standard model backgrounds. model-independent upper limits are placed on the visible cross-sections for events with a higgs boson decaying into $b\bar{b}$ and large missing transverse momentum with thresholds ranging from 150 gev to 400 gev. results are interpreted using a simplified model with a $z^\prime$ gauge boson decaying into different higgs bosons predicted in a two-higgs-doublet model, of which the heavy pseudoscalar higgs decays into a pair of dark matter particles. exclusion limits are also presented for the mass scales of various effective field theory operators that describe the interaction between dark matter particles and the higgs boson. | search for dark matter produced in association with a higgs boson decaying to two bottom quarks in $pp$ collisions at $\\sqrt{s} = 8$ tev with the atlas detector |
we demonstrate the feasibility of generation of quasi-stable counter-propagating solitonic structures in an atomic bose-einstein condensate confined in a realistic toroidal geometry, and identify optimal parameter regimes for their experimental observation. using density engineering we numerically identify distinct regimes of motion of the emerging macroscopic excitations, including both solitonic motion along the azimuthal ring direction, such that structures remain visible after multiple collisions even in the presence of thermal fluctuations, and snaking instabilities leading to the decay of the excitations into vortical structures. our analysis, which considers both mean field effects and fluctuations, is based on the ring trap geometry of murray et al (2013 phys. rev. a88 053615). | engineering dark solitary waves in ring-trap bose-einstein condensates |
the muon g -2 anomaly was strengthened by recent experimental results at fermilab, which may be signatures of new physics. a scenario of leptophilic scalar ϕl accounting for the muon g -2 anomaly is investigated in this paper. although a light ϕl mainly decaying into standard model (sm) particles has been excluded by experiments, a dark leptophilic scalar ϕl predominantly decaying into invisible fermionic dark matter (dm) χ χ ¯ is still allowed. considering the decay mode ϕl→χ χ ¯ opened (here mϕ l=3 mχ ), the coupling preferred by the muon g -2 and the ϕl-χ coupling are derived. the light/heavy ϕl (roughly 1 gev as a benchmark value) can be tested by future experiments via dm/sm decay modes, and the contribution of ϕl to the anomalous magnetic moment of the tau lepton could be investigated at lepton colliders. the search for χ via χ -electron scattering in direct detection of dm is not sensitive due to a tiny ϕl-electron coupling, especially for mχ≳mμ. | a dark leptophilic scalar with the updated muon g -2 anomaly |
heat and noise control is essential for the continued development of quantum technologies. for this purpose, a particularly powerful tool is the heat rectifier, which allows for heat transport in one configuration of two baths but not the reverse. here we propose a class of rectifiers that exploits the unidirectionality of a low temperature bath to force the system into a dark state, thus blocking heat transport in one configuration of the two baths. however, if the two baths are switched around, a heat current is observed. an implementation using a qutrit coupled to two harmonic oscillators is proposed and rectification values beyond 103 are achieved for realistic parameter values. furthermore, we show that the heat current can be amplified by an order of magnitude through external driving without diminishing the diode functionality. the heat rectification effect is seen for a large range of parameters and it is robust towards both decay and dephasing. | dark-state-induced heat rectification |
a higgs portal in the form of the operator |h|2 provides a minimal and theoretically motivated link between the standard model (sm) and new physics. while higgs portals can be constrained well by exotic higgs decays if the beyond-the-sm states are light, testing scenarios where these particles are kinematically inaccessible is known to be challenging. we explore the sensitivity of future hadron collider measurements of zz → 4ℓ production in constraining higgs portal interactions. it is shown that by using a matrix-element based kinematic discriminant the reach of the high-luminosity option of the large hadron collider (lhc) can be significantly enhanced compared to studies that are based on measurements of the four-lepton invariant mass spectrum alone. we also analyse the potential of the high-energy upgrade of the lhc and a future circular collider in constraining new physics that couples to |h|2. the obtained constraints are compared to the limits one expects to find from other single-higgs probes. in addition, we provide an independent analysis of the relevant higgs portal effects in double-higgs production. we find that the constraints obtained from our zz → 4ℓ analysis turn out to be both competitive with and complementary to the projected limits obtained using other search techniques. | probing higgs portals with matrix-element based kinematic discriminants in zz → 4ℓ production |
the origin of life, based on the homochirality of biomolecules, is a persistent mystery. did life begin by using both forms of chirality, and then one of the forms disappeared? or did the choice of homochirality precede the formation of biomolecules that could ensure replication and information transfer? is the natural choice of l-amino acids and d-sugars on which life is based deterministic or random? is the handedness present in/of the universe from its beginning? the whole biosystem on the earth, all living creatures are chiral. many theories try to explain the origin of life and chirality on the earth: e.g., the panspermia hypothesis, the primordial soup hypothesis, theory of parity violation in weak interactions. additionally, heavy neutrinos and the impact of the fact that only left-handed particles decay, and even dark matter, all have to be considered. | chirality and the origin of life |
two-dimensional (2d) heterostructure with atomically sharp interface holds promise for future electronics and optoelectronics because of their multi-functionalities. here we demonstrate gate-tunable rectifying behavior and self-powered photovoltaic characteristics of novel p-gese/n-mose2 van der waal heterojunction (vdw hj). a substantial increase in rectification behavior was observed when the devices were subjected to gate bias. the highest rectification of ~ 1 × 104 was obtained at vg = - 40 v. remarkable rectification behavior of the p-n diode is solely attributed to the sharp interface between metal and gese/mose2. the device exhibits a high photoresponse towards nir (850 nm). a high photoresponsivity of 465 maw-1, an excellent eqe of 670%, a fast rise time of 180 ms, and a decay time of 360 ms were obtained. furthermore, the diode exhibits detectivity (d) of 7.3 × 109 jones, the normalized photocurrent to the dark current ratio (npdr) of 1.9 × 1010 w-1, and the noise equivalent power (nep) of 1.22 × 10-13 whz-1/2. the strong light-matter interaction stipulates that the gese/mose2 diode may open new realms in multi-functional electronics and optoelectronics applications. | nir self-powered photodetection and gate tunable rectification behavior in 2d gese/mose2 heterojunction diode |
motivated by the difficulty of constructing de sitter vacua in string theory, a new approach was proposed in arxiv:1807.01570 and arxiv:1907.04268, where four dimensional de sitter space was realized as the effective cosmology, with matter and radiation, on an expanding spherical bubble that mediates the decay of non supersymmetric ads5 to a more stable ads5 in string theory. in this third installment, we further expand on this scenario by considering the backreaction of matter in the bulk and on the brane in terms of how the brane bends. we compute the back reacted metric on the bent brane as well as in the five dimensional bulk. to further illuminate the effect of brane-bending, we compare our results with an explicit computation of the five dimensional graviton propagator using a holographic prescription. finally we comment on a possible localization of four dimensional gravity in our model using two colliding branes. | dark bubbles: decorating the wall |
we update the parameter spaces for both a real and complex scalar dark matter via the higgs portal. in the light of constraints arising from the lux 2016 data, the latest higgs invisible decay and the gamma ray spectrum, the dark matter resonant mass region is further restricted to a narrow window between 54.9-62.3 gev in both cases, and its large mass region is excluded until 834 gev and 3473 gev for the real and complex scalar, respectively. | scalar dark matter: real vs complex |
we report an experimental study of temperature-dependent spectral line shapes of phonon sideband emission stemming from dark excitons in monolayer and bilayer wse2. using photoluminescence spectroscopy in the range from 4 to 100 k, we observe a pronounced asymmetry in the phonon-assisted luminescence from momentum-indirect exciton reservoirs. we demonstrate that the corresponding spectral profiles are distinct from those of bright excitons with direct radiative decay pathways. the line-shape asymmetry reflects thermal distribution of exciton states with finite center-of-mass momenta, characteristic for phonon sideband emission. the extracted temperature of the exciton reservoirs is found to generally follow that of the crystal lattice, with deviations reflecting overheated populations. the latter are most pronounced in the bilayer case and at lowest temperatures. our results add to the understanding of phonon-assisted recombination of momentum-dark excitons and, more generally, establish means to access the thermal distribution of finite-momentum excitons in atomically thin semiconductors with indirect band gaps. | spectral asymmetry of phonon sideband luminescence in monolayer and bilayer wse2 |
we study phenomenology of electroweak-interacting fermionic dark matter (dm) with a mass of o (100) gev. constructing the effective lagrangian that describes the interactions between the higgs boson and the su (2)l isospin multiplet fermion, we evaluate the electric dipole moment (edm) of electron, the signal strength of higgs boson decay to two photons and the spin-independent elastic-scattering cross section with proton. as representative cases, we consider the su (2)l triplet fermions with zero/nonzero hypercharges and su (2)l doublet fermion. it is found that the electron edm gives stringent constraints on those model parameter spaces. in the cases of the triplet fermion with zero hypercharge and the doublet fermion, the higgs signal strength does not deviate from the standard model prediction by more than a few % once the current dm direct detection constraint is taken into account, even if the cp violation is suppressed. on the contrary, o (10- 20)% deviation may occur in the case of the triplet fermion with nonzero hypercharge. our representative scenarios may be tested by the future experiments. | effective interaction of electroweak-interacting dark matter with higgs boson and its phenomenology |
observables sensitive to the anomalous production of events containing hadronic jets and missing momentum in the plane transverse to the proton beams at the large hadron collider are presented. the observables are defined as a ratio of cross sections, for events containing jets and large missing transverse momentum to events containing jets and a pair of charged leptons from the decay of a $z/\gamma^\ast$ boson. this definition minimises experimental and theoretical systematic uncertainties in the measurements. this ratio is measured differentially with respect to a number of kinematic properties of the hadronic system in two phase-space regions; one inclusive single-jet region and one region sensitive to vector-boson-fusion topologies. the data are found to be in agreement with the standard model predictions and used to constrain a variety of theoretical models for dark-matter production, including simplified models, effective field theory models, and invisible decays of the higgs boson. the measurements use 3.2 fb$^{-1}$ of proton--proton collision data recorded by the atlas experiment at a centre-of-mass energy of 13 tev and are fully corrected for detector effects, meaning that the data can be used to constrain new-physics models beyond those shown in this paper. | measurement of detector-corrected observables sensitive to the anomalous production of events with jets and large missing transverse momentum in $pp$ collisions at $\\sqrt{s} = 13$ tev using the atlas detector |
we propose a simple mechanism for copiously producing heavy higgs bosons with enhanced decay rates to two photons at the lhc, within the context of the minimal supersymmetric extension of the standard model (mssm). in the cp-conserving limit of the theory, such a diphoton resonance may be identified with the heavier cp-even h boson, whose gluon-fusion production and decay into two photons are enhanced by loops of the lightest supersymmetric partner of the top quark t∼1 when its mass mt∼1 happens to be near the t∼1 * t∼1 threshold, i.e. for mt∼1 ≃1/2mh. the scenario requires a relatively low supersymmetry-breaking scale ms ≲ 1 tev, but large values of the higgsino mass parameter, μ ≳ 1 tev, that lead to a strong ht∼1 * t∼1 coupling. such parameters can accommodate the observed mass and standard-like couplings of the 125 gev h boson in the mssm, while satisfying all other constraints from the lhc and dark matter searches. additional enhancement to the diphoton rate could be provided by coulombic qcd corrections and, to a lesser extent, by resonant contributions due to t∼1 * t∼1 bound states. to discuss the characteristic features of such a scenario, we consider as an illustrative example the case of a diphoton resonance with a mass of approximately 750 gev, for which an excess was observed in the early lhc 13 tev data and which later turned out to be simply a statistical fluctuation. | enhanced rates for diphoton resonances in the mssm |
we propose a simple way to extract particle masses given a displaced vertex signature in event topologies where two long-lived mother particles decay to visible particles and an invisible daughter. the mother could be either charged or neutral and the neutral daughter could correspond to a dark matter particle in different models. the method allows to extract the parent and daughter masses by using on-shell conditions and energy-momentum conservation, in addition to the displaced decay positions of the parents, which allows to solve the kinematic equations fully on an event-by-event basis. we show the validity of the method by means of simulations including detector effects. if displaced events are seen in discovery searches at the large hadron collider (lhc), this technique can be applied. | reconstructing particle masses in events with displaced vertices |
a search is presented for dark matter produced in association with a hadronically decaying w or z boson using 3.2 fb-1 of pp collisions at √{ s} = 13 tev recorded by the atlas detector at the large hadron collider. events with a hadronic jet compatible with a w or z boson and with large missing transverse momentum are analysed. the data are consistent with the standard model predictions and are interpreted in terms of both an effective field theory and a simplified model containing dark matter. | search for dark matter produced in association with a hadronically decaying vector boson in pp collisions at √{ s} = 13 tev with the atlas detector |
the first search for supersymmetry in events with an experimental signature of one soft, hadronically decaying $\tau$ lepton, one energetic jet from initial-state radiation, and large transverse momentum imbalance is presented. these event signatures are consistent with direct or indirect production of scalar $\tau$ leptons ($\tilde{\tau}$) in supersymmetric models that exhibit coannihilation between the $\tilde{\tau}$ and the lightest neutralino ($\tilde{\chi}^0_1$), and that could generate the observed relic density of dark matter. the data correspond to an integrated luminosity of 77.2 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} =$ 13 tev collected with the cms detector at the lhc in 2016 and 2017. the results are interpreted in a supersymmetric scenario with a small mass difference ($\delta m$) between the chargino ($\tilde{\chi}^\pm_1$) or next-to-lightest neutralino ($\tilde{\chi}^0_2$), and the $\tilde{\chi}^0_1$. the mass of the $\tilde{\tau}$ is assumed to be the average of the $\tilde{\chi}^\pm_1$ and $\tilde{\chi}^0_1$ masses. the data are consistent with standard model background predictions. upper limits at 95% confidence level are set on the sum of the $\tilde{\chi}^\pm_1$, $\tilde{\chi}^0_2$, and $\tilde{\tau}$ production cross sections for $\delta m(\tilde{\chi}^\pm_1, \tilde{\chi}^0_1) =$ 50 gev, resulting in a lower limit of 290 gev on the mass of the $\tilde{\chi}^\pm_1$, which is the most stringent to date and surpasses the bounds from the lep experiments. | search for supersymmetry with a compressed mass spectrum in events with a soft $\\tau$ lepton, a highly energetic jet, and large missing transverse momentum in proton-proton collisions at $\\sqrt{s} =$ 13 tev |
in this paper, we study friedmann cosmology with time-varying vacuum energy density in the context of brans-dicke theory. we consider an isotropic and homogeneous flat space, filled with a matter-dominated perfect fluid and a dynamical cosmological term λ (t ) , obeying the equation of state of the vacuum. as the exact nature of a possible time-varying vacuum is yet to be found, we explore λ (t ) given by the phenomenological law λ (t )=λ +σ h , where λ and σ are positive constants. we solve the model and then focus on two different cases λh 1 and λh 2 by assuming λ =λ and λ =σ h , respectively. notice that λh 1 is the analog of the standard λ cdm, but within the brans-dicke cosmology. we find the analytical solution of the main cosmological functions such as the hubble parameter, the scale factor, deceleration and equation of state parameters for these models. in order to test the viability of the cosmological scenarios, we perform two sets of joint observational analyses of the recent type ia supernova data (pantheon), observational measurements of hubble parameter data, baryon acoustic oscillation/cosmic microwave background data and local hubble constant for each model. for the sake of comparison, the same data analysis is performed for the λ cdm model. each model shows a transition from decelerated phase to accelerated phase and can be viewed as an effective quintessence behavior. using the model selection criteria aic and bic to distinguish from existing dark energy models, we find that the brans-dicke analog of the λ -cosmology (i.e. our model λh 1) performs at a level comparable to the standard λ cdm, whereas λh 2 is less favoured. | friedmann cosmology with decaying vacuum density in brans-dicke theory |
we develop a general quantum theory of the coupled plasmonic modes resulting from the near-field interaction between localized surface plasmons in a heterogeneous metallic nanoparticle dimer. in particular, we provide analytical expressions for the frequencies and decay rates of the bright and dark plasmonic modes. we show that, for sufficiently small nanoparticles, the main decay channel for the dark plasmonic mode, which is weakly coupled to light and, hence, immune to radiation damping, is of nonradiative origin and corresponds to landau damping, i.e., decay into electron-hole pairs. | decay of dark and bright plasmonic modes in a metallic nanoparticle dimer |
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