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1512.00280
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we study the rotor - router walk on the infinite square lattice with the outgoing edges at each lattice site ordered clockwise . in the previous paper [ j.phys.a : math . theor . 48 , 285203 ( 2015 ) ] , we have considered the loops created by rotors and labeled sites where the loops become closed . the sequence of labels in the rotor - router walk was conjectured to form a spiral structure obeying asymptotically an archimedean property . in the present paper , we select a subset of labels called `` nodes '' and consider spirals formed by nodes . the new spirals are directly related to tree - like structures which represent the evolution of the cluster of vertices visited by the walk . we show that the average number of visits to the origin @xmath0 by the moment @xmath1 is @xmath2 where @xmath3 is the average number of rotations of the spiral . _ keywords _ : rotor - router walk , archimedean spiral , sub - diffusion .
| 175
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1603.07480
|
the density matrix of hawking radiation is calculated in the model of black hole with fluctuating horizon . quantum fluctuations smear the classical horizon of black hole and modify the density matrix of radiation producing the off - diagonal elements . the off - diagonal elements may store information of correlations between radiation and black hole . the smeared density matrix was constructed by convolution of the density matrix calculated with the instantaneous horizon with the gaussian distribution over the instantaneous horizons . the distribution has the extremum at the classical radius of the black hole and the width of order of the planck length . calculations were performed in the model of black hole formed by the thin collapsing shell which follows a trajectory which is a solution of the matching equations connecting the interior and exterior geometries . * density matrix of radiation of black hole with fluctuating horizon * * mikhail z. iofa * skobeltsyn institute of nuclear physics moscow state university moscow 119991 , russia
| 169
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1606.06449
|
an exp - algebraic curve consists of a compact riemann surface @xmath0 together with @xmath1 equivalence classes of germs of meromorphic functions modulo germs of holomorphic functions , @xmath2 , \cdots , [ h_n ] \}$ ] , with poles of orders @xmath3 at points @xmath4 . this data determines a space of functions @xmath5 ( respectively , a space of @xmath6-forms @xmath7 ) holomorphic on the punctured surface @xmath8 with exponential singularities at the points @xmath4 of types @xmath9 , \cdots , [ h_n]$ ] , i.e. , near @xmath10 any @xmath11 is of the form @xmath12 for some germ of meromorphic function @xmath13 ( respectively , any @xmath14 is of the form @xmath15 for some germ of meromorphic @xmath6-form ) . for any @xmath14 the completion of @xmath16 with respect to the flat metric @xmath17 gives a space @xmath18 obtained by adding a finite set @xmath19 of @xmath20 points , and it is known that integration along curves produces a nondegenerate pairing of the relative homology @xmath21 with the derham cohomology group defined by @xmath22 . there is a degree zero line bundle @xmath23 associated to an exp - algebraic curve , with a natural isomorphism between @xmath7 and the space @xmath24 of meromorphic @xmath23-valued @xmath6-forms which are holomorphic on @xmath16 , so that @xmath21 maps to a subspace @xmath25 . we show that the exp - algebraic curve @xmath26 is determined uniquely by the pair @xmath27 . [ section ] [ theorem]proposition [ theorem]lemma [ theorem]corollary [ theorem]definition
| 251
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1404.2685
|
predator - prey relationships are one of the most studied interactions in population ecology . however , little attention has been paid to the possibility of role exchange between species once determined as predators and preys , despite firm field evidence of such phenomena in the nature . in this paper , we build a model capable of reproducing the main phenomenological features of one reported predator - prey role - reversal system , and present results for both the homogeneous and the space explicit cases . we find that , depending on the choice of parameters , our role - reversal dynamical system exhibits excitable - like behaviour , generating waves of species concentrations that propagate through space .
| 120
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0907.0063
|
because of the lack of reliable sunspot observation , the quality of sunspot number series is poor in the late 18th century , leading to the abnormally long solar cycle ( 17841799 ) before the dalton minimum . using the newly recovered solar drawings by the 1819th century observers staudacher and hamilton , we construct the solar butterfly diagram , i.e. the latitudinal distribution of sunspots in the 1790 s . the sudden , systematic occurrence of sunspots at high solar latitudes in 17931796 unambiguously shows that a new cycle started in 1793 , which was lost in traditional wolf s sunspot series . this finally confirms the existence of the lost cycle that has been proposed earlier , thus resolving an old mystery . this letter brings the attention of the scientific community to the need of revising the sunspot series in the 18th century . the presence of a new short , asymmetric cycle implies changes and constraints to sunspot cycle statistics , solar activity predictions , solar dynamo theories as well as for solar - terrestrial relations .
| 181
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nlin0207006
|
the paper is an attempt to relate two vast areas of the applicability of the renormalization group ( rg ) : field theoretic models and partial differential equations . it is shown that the green function of a nonlinear diffusion equation can be viewed as a correlation function in a field - theoretic model with an ultralocal term , concentrated at a spacetime point . this field theory is shown to be multiplicatively renormalizable , so that the rg equations can be derived in a standard fashion , and the rg functions ( the @xmath0 function and anomalous dimensions ) can be calculated within a controlled approximation . a direct calculation carried out in the two - loop approximation for the nonlinearity of the form @xmath1 , where @xmath2 is not necessarily integer , confirms the validity and self - consistency of the approach . the explicit self - similar solution is obtained for the infrared asymptotic region , with exactly known exponents ; its range of validity and relationship to previous treatments are briefly discussed .
| 177
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1411.0271
|
when a quantum state undergoes a quantum channel , the state will be inevitably influenced . in general , the fidelity of the state is reduced , so is the entanglement if the subsystems go through the channel . however , the influence on the coherence of the state is quite different . here we present some state - independent quantities to describe to what degree the fidelity , the entanglement and the coherence of the state are influenced . as applications , we consider some quantum channels on a qubit and find that the infidelity ability monotonically depends on the decay rate , but in usual the decoherence ability is not the case and strongly depends on the channel .
| 121
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1011.4513
|
it is shown that the bond - decorated ising model is a realistic model for certain real magnetic compounds containing lanthanide ions . the lanthanide ion plays the role of ising spin . the required conditions on the crystal - field spectrum of the lanthanide ion for the model to be valid are discussed and found to be in agreement with several recent _ ab initio _ calculations on centers . similarities and differences between the spectra of the simple ising chain and the decorated ising chain are discussed and illustrated , with attention to level crossings in a magnetic field . the magnetic properties of two actual examples ( a [ dycumocu]@xmath0 chain and a ring ) are obtained by a transfer - matrix solution of the decorated ising model . @xmath1-factors of the metal ions are directly imported from _ ab initio _ results , while exchange coupling constants are fitted to experiment . agreement with experiment is found to be satisfactory , provided one includes a correction ( from _ ab initio _ results ) for susceptibility and magnetization to account for the presence of excited kramers doublets on .
| 193
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1512.08004
|
we show that linear scalar waves are bounded and continuous up to the cauchy horizon of reissner de sitter and kerr de sitter spacetimes , and in fact decay exponentially fast to a constant along the cauchy horizon . we obtain our results by modifying the spacetime beyond the cauchy horizon in a suitable manner , which puts the wave equation into a framework in which a number of standard as well as more recent microlocal regularity and scattering theory results apply . in particular , the conormal regularity of waves at the cauchy horizon which yields the boundedness statement is a consequence of radial point estimates , which are microlocal manifestations of the blue - shift and red - shift effects .
| 123
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nucl-th0406012
|
this talk reviews three inputs important to neutrino - induced nucleosynthesis in a supernova : 1 ) `` standard '' properties of the supernova neutrino flux , 2 ) effects of phenomena like neutrino oscillations on that flux , and 3 ) nuclear structure issues in estimating cross sections for neutrino - nucleus interactions . the resulting possibilities for neutrino - induced nucleosynthesis or the @xmath0-process in massive stars are discussed . this includes two relatively recent extensions of @xmath0-process calculations to heavier nuclei , one focused on understanding the origin of @xmath1la and @xmath2ta and the second on the effects following @xmath3-process freezeout . from calculations of the neutrino post - processing of the @xmath3-process distribution , limits can be placed on the neutrino fluence after freezeout and thus on the dynamic timescale for the expansion .
| 138
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1608.02853
|
we study quantum discord between two free modes of a massive scalar field in a maximally entangled state in de sitter space . we introduce two observers , one in a global chart and the other in an open chart of de sitter space , and the observers determine the quantum discord created by each detecting one of the modes this situation is analogous to the relationship between an observer in a minkowski chart and another in one of the two rindler charts in flat space . we find that the state becomes less entangled as the curvature of the open chart gets larger . in particular , for the cases of a massless , and a conformally coupled scalar field , the entanglement vanishes in the limit of infinite curvature . however , we find that the quantum discord never disappears even in the limit that entanglement disappears . = 1 mm kobe - cosmo-16 - 09 + sugumi kanno@xmath0 , jonathan p. shock@xmath1 and jiro soda@xmath2 1.5 cm
| 170
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hep-ph9806351
|
we present a detailed analysis of multiple production of the lightest @xmath0-even higgs boson ( @xmath1 ) of the minimal supersymmetric standard model ( mssm ) at high - energy @xmath2 colliders . we consider the production of the heavier @xmath0-even higgs boson ( @xmath3 ) via higgs - strahlung @xmath4 , in association with the @xmath0-odd higgs boson ( @xmath5 ) in @xmath6 , or via the fusion mechanism @xmath7 , with @xmath3 subsequently decaying through @xmath8 , thereby resulting in a pair of lighter higgs bosons ( @xmath1 ) in the final state . these processes can enable one to measure the trilinear higgs couplings @xmath9 and @xmath10 , which can be used to theoretically reconstruct the higgs potential . we delineate the regions of the mssm parameter space in which these trilinear higgs couplings could be measured at a future @xmath11 collider . in our calculations , we include in detail the radiative corrections to the higgs sector of the mssm , especially the mixing in the squark sector . cern - th/98 - 189 + hep - ph/9806351 * measuring the trilinear couplings of mssm + neutral higgs bosons at high - energy @xmath2 colliders * 0.5 cm p. osland@xmath12 and p. n. pandita@xmath13 + @xmath14 department of physics , university of bergen , n-5007 bergen , norway@xmath15 + @xmath16 deutsches elektronen - synchrotron desy , d-22603 hamburg , germany + @xmath17 theoretical physics division , cern , ch 1211 geneva 23 , switzerland + @xmath18 department of physics , north eastern hill university , shillong 793 022 , india@xmath15 + pacs : 14.80.cp , 12.60.jv , 13.90.+i + * permanent addresses cern - th/98 - 189 + june 1998
| 284
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1610.04539
|
in this work we generalize the models for nonlinear waves in a gas liquid mixture taking into account an interphase heat transfer , a surface tension and a weak liquid compressibility simultaneously at the derivation of the equations for nonlinear waves . we also take into consideration high order terms with respect to the small parameter . two new nonlinear differential equations are derived for long weakly nonlinear waves in a liquid with gas bubbles by the reductive perturbation method considering both high order terms with respect to the small parameter and the above mentioned physical properties . one of these equations is the perturbation of the burgers equation and corresponds to main influence of dissipation on nonlinear waves propagation . the other equation is the perturbation of the burgers korteweg de vries equation and corresponds to main influence of dispersion on nonlinear waves propagation . _ keywords : _ nonlinear waves ; liquid with gas bubbles ; reductive perturbation method ; perturbed burgers equation ; nonlinear evolution equations .
| 170
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0712.4038
|
in this work we develop a new propagation model for the galactic cosmic rays based on the galprop code , including contributions from dark matter annihilation . its predictions of the galactic diffuse @xmath0 ray spectra are compatible with the egret data in all sky regions . it also gives consistent results about the diffuse @xmath0 ray longitude and latitude distributions . the b / c , @xmath1be/@xmath2be , proton , electron and antiproton spectra are in agreement with cosmic ray measurements as well . in this model we have taken a universal proton spectrum throughout the galaxy without introducing large fluctuation , considering the proton energy loss is negligible . the dark matter annihilation signals are `` boosted '' after taking the contributions from subhalos into account . another interesting feature of this model is that it gives better description of the diffuse @xmath0 rays when taking the source distribution compatible with supernova remnants data , which is different from previous studies .
| 164
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astro-ph0609727
|
using the _ hubble space telescope _ , we have obtained the first color - magnitude diagram ( cmd ) to reach the main - sequence turnoff of the galactic globular cluster ngc 6388 . from a comparison between the cluster cmd and 47 tucanae s , we find that the bulk of the stars in these two clusters have nearly the same age and chemical composition . on the other hand , our results indicate that the blue horizontal branch and rr lyrae components in ngc 6388 are intrinsically overluminous , which must be due to one or more , still undetermined , non - canonical second parameter(s ) affecting a relatively minor fraction of the stars in ngc 6388 .
| 122
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astro-ph0208089
|
based on simultaneous observations of solar flares in hard and soft x - rays we studied several aspects of the neupert effect . about half of 1114 analyzed events show a timing behavior consistent with the effect . for these events , a high correlation between the soft peak flux and the hard fluence is obtained , being indicative of electron - beam - driven evaporation . however , for about one fourth of the events there is strong evidence for an additional heating agent other than electron beams . we discuss the relevance of these findings with respect to parker s idea of coronal heating by nanoflares .
| 109
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quant-ph0208080
|
it is known that in phase covariant quantum cloning the equatorial states on the bloch sphere can be cloned with a fidelity higher than the optimal bound established for universal quantum cloning . we generalize this concept to include other states on the bloch sphere with a definite @xmath0 component of spin . it is shown that once we know the @xmath0 component , we can always clone a state with a fidelity higher than the universal value and that of equatorial states . we also make a detailed study of the entanglement properties of the output copies and show that the equatorial states are the only states which give rise to separable density matrix for the outputs .
| 119
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1009.0225
|
we consider the region @xmath0 in spacetime containing future - trapped closed surfaces and its boundary @xmath1 , and derive some of their general properties . we then concentrate on the case of spherical symmetry , but the methods we use are general and applicable to other situations . we argue that closed trapped surfaces have a non - local property , clairvoyance " , which is inherited by @xmath1 . we prove that @xmath1 is not a marginally trapped tube in general , and that it can have portions in regions whose whole past is flat . for asymptotically flat black holes , we identify a general past barrier , well inside the event horizon , to the location of @xmath1 under physically reasonable conditions . we also define the core @xmath2 of the trapped region as that part of @xmath0 which is indispensable to sustain closed trapped surfaces . we prove that the unique spherically symmetric dynamical horizon is the boundary of such a core , and we argue that this may serve to single it out . to illustrate the results , some explicit examples are discussed , namely robertson - walker geometries and the imploding vaidya spacetime . pacs : 04.70.bw , 04.20.cv
| 207
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1511.06375
|
we consider a model of neutrino mass with a scalar triplet @xmath0 assigned lepton number @xmath1 , so that the tree - level yukawa coupling @xmath2 is not allowed . it is generated instead through the interaction of @xmath3 and @xmath4 with dark matter and the soft breaking of @xmath5 to @xmath6 . we discuss the phenomenological implications of this model , including @xmath7 decay and the prognosis of discovering the dark sector at the large hadron collider . ucrhep - t557 + november 2015 * type ii radiative seesaw model of + neutrino mass with dark matter + *
| 100
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1610.01054
|
a numerical algorithm that computes the decomposition of a finite - dimensional unitary reducible representation of a compact lie group is presented . the algorithm , inspired by notions of quantum mechanics , generates two adapted states and , after appropriate algebraic manipulations , returns the block matrix structure of the representation in terms of its irreducible components . it also provides an adapted orthonormal basis . the algorithm can be used to compute the clebsch gordan coefficients of the tensor product of irreducible representations of a given compact lie group . the performance of the algorithm is tested on various examples : the decomposition of the regular representation of finite groups and the computation of the clebsch gordan coefficients of tensor products of representations of @xmath0 .
| 128
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1606.09515
|
we study vector fields of the plane preserving the form of liouville . we present their local models up to the natural equivalence relation , and describe local bifurcations of low codimension . to achieve that , a classification of univariate functions is given , according to a relation stricter than contact equivalence . we discuss , in addition , their relation with strictly contact vector fields in dimension three . analogous results for diffeomorphisms are also given . * keywords * systems preserving the form of liouville , strictly contact systems , classification , bifurcations + * msc[2000 ] * primary 37c15 , 37j10 , secondary 58k45 , 53d10
| 110
|
1305.0166
|
while the properties of the 125 gev higgs boson - like particle observed by the atlas and cms collaborations are largely compatible with those predicted for the standard model state , significant deviations are present in some cases . we , therefore , test the viability of a beyond the standard model scenario based on supersymmetry , the cp - violating next - to - minimal supersymmetric standard model , against the corresponding experimental observations . namely , we identify possible model configurations in which one of its higgs bosons is consistent with the lhc observation and evaluate the role of the explicit complex phases in both the mass and di - photon decay of such a higgs boson . through a detailed analysis of some benchmark points corresponding to each of these configurations , we highlight the impact of the cp - violating phases on the model predictions compared to the cp - conserving case . shep-13 - 07 + april 2013 * 125 gev higgs boson signal within the complex nmssm * + + _ @xmath0 school of physics & astronomy , + university of southampton , southampton so17 1bj , uk . _ + _ @xmath1 national centre for nuclear research , ho . za 69 , 00 - 681 warsaw , poland . _ + _ @xmath2 department of physics , + iit guwahati , assam 781039 , india . _ + @xmath3e - mails : + , + smunir@fuw.edu.pl , + poulose@iitg.ernet.in .
| 248
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0711.1063
|
we discuss a possible spectral realization of the riemann zeros based on the hamiltonian @xmath0 perturbed by a term that depends on two potentials , which are related to the berry - keating semiclassical constraints . we find perturbatively the potentials whose jost function is given by the zeta function @xmath1 for @xmath2 . for @xmath3 we find the potentials that yield the smooth approximation to the zeros . we show that the existence of potentials realizing the zeta function at @xmath3 , as a jost function , would imply that the riemann zeros are point like spectrum embedded in the continuum , resolving in that way the emission / spectral interpretation . = cmss12 = cmu10 scaled1 h 0.2 cm \def\ ] ] ] @xmath4 ) # 1#2#1 # 2 # 11 # 1 # 1#1 # 1#2#1 # 2 # 1#1 # 1 | # 1 pi # 1e^^#1 # 1_#1 # 1#2 # 1 , # 2 pi # 1e^^#1 # 1_#1 = cmss12 = cmu10 scaled1 l
| 171
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1008.1092
|
we provide an overview of stellar variability in the first quarter of data from the _ kepler _ mission . the intent of this paper is to examine the entire sample of over 150,000 target stars for periodic behavior in their lightcurves , and relate this to stellar characteristics . these data constitute an unprecedented study of stellar variability given its great precision and complete time coverage ( with a half hour cadence ) . because the full kepler pipeline is not currently suitable for a study of stellar variability of this sort , we describe our procedures for treating the raw " pipeline data . about half of the total sample exhibits convincing periodic variability up to two weeks , with amplitudes ranging from differential intensity changes less than 10@xmath0 up to more than 10 percent . k and m dwarfs have a greater fraction of period behavior than g dwarfs . the giants in the sample have distinctive quasi - periodic behavior , but are not periodic in the way we define it . not all periodicities are due to rotation , and the most significant period is not necessarily the rotation period . we discuss properties of the lightcurves , and in particular look at a sample of very clearly periodic g dwarfs . it is clear that a large number of them do vary because of rotation and starspots , but it will take further analysis to fully exploit this . = 1
| 247
|
cond-mat0410410
|
a rational representation for the self energy is explored to interpolate the solution of the anderson impurity model in general orbitally degenerate case . several constrains such as the friedel s sum rule , positions of the hubbard bands as well as the value of quasiparticle residue are used to establish the equations for the coefficients of the interpolation . we employ two fast techniques , the slave boson mean field and the hubbard i approximations to determine the functional dependence of the coefficients on doping , degeneracy and the strength of the interaction . the obtained spectral functions and self energies are in good agreement with the results of numerically exact quantum monte carlo method .
| 117
|
1508.05227
|
we investigate linear and inverse seesaw mechanisms with maximal zero textures of the constituent matrices subjected to the assumption of non - zero eigenvalues for the neutrino mass matrix @xmath0 and charged lepton mass matrix @xmath1 . if we restrict to the minimally parametrized non - singular ` @xmath1 ' ( i.e. , with maximum number of zeros ) it gives rise to only 6 possible textures of @xmath1 . non - zero determinant of @xmath0 dictates six possible textures of the constituent matrices . we ask in this minimalistic approach , what are the phenomenologically allowed maximum zero textures are possible . it turns out that inverse seesaw leads to 7 allowed two - zero textures while the linear seesaw leads to only one . in inverse seesaw , we show that 2 is the maximum number of independent zeros that can be inserted into @xmath2 to obtain all 7 viable two - zero textures of @xmath0 . on the other hand , in linear seesaw mechanism , the minimal scheme allows maximum 5 zeros to be accommodated in ` @xmath3 ' so as to obtain viable effective neutrino mass matrices ( @xmath0 ) . interestingly , we find that our minimalistic approach in inverse seesaw leads to a realization of all the phenomenologically allowed two - zero textures whereas in linear seesaw only one such texture is viable . next our numerical analysis shows that none of the two - zero textures give rise to enough cp violation or significant @xmath4 . therefore , if @xmath5 is established , our minimalistic scheme may still be viable provided we allow more number of parameters in ` @xmath1 ' . = 1
| 282
|
0708.0163
|
using the effective potential approach for composite operators , we have formulated a general method of calculation of the truly non - perturbative yang - mills vacuum energy density ( this is , by definition , the bag constant apart from the sign ) . it is the main dynamical characteristic of the qcd ground state . our method allows one to make it free of the perturbative contributions ( contaminations ) , by construction . we also perform an actual numerical calculation of the bag constant for the confining effective charge . its choice uniquely defines the bag constant , which becomes free of all the types of the perturbative contributions now , as well as possessing many other desirable properties as colorless , gauge independence , etc . using further the trace anomaly relation , we develop a general formalism which makes it possible to relate the bag constant to the gluon condensate defined at the same @xmath0 function ( or , equivalently , effective charge ) which has been chosen for the calculation of the bag constant itself . our numerical result for it shows a good agreement with other phenomenological estimates of the gluon condensate . we have argued that the calculated bag constant may contribute to the dark energy density . its contribution is by 10 orders of magnitude better than the estimate from the higgs field s contribution . we also propose to consider the bag energy as a possible amount of energy which can be released from the qcd ground state by a single cycle . the qcd ground state is shown to be an infinite and hence a permanent reservoir of energy .
| 281
|
1606.02667
|
we discuss the rnyi entanglement entropies of descendant states in critical one - dimensional systems with boundaries , that map to boundary conformal field theories in the scaling limit . we unify the previous conformal - field - theory approaches to describe primary and descendant states in systems with both open and closed boundaries . we provide universal expressions for the first two descendants in the identity family . we apply our technique to critical systems belonging to different universality classes with non - trivial boundary conditions that preserve conformal invariance , and find excellent agreement with numerical results obtained for finite spin chains . we also demonstrate that entanglement entropies are a powerful tool to resolve degeneracy of higher excited states in critical lattice models .
| 127
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astro-ph0307483
|
we report detection of continuum emission at @xmath0 and 450 @xmath1 m from disks around four classical t tauri stars in the mbm 12 ( l1457 ) young association . using a simple model we infer masses of 0.00140.012 m@xmath2 for the disk of lkh@xmath3 263 abc , 0.0050.021 m@xmath2 for s18 abab , 0.030.18 m@xmath2 for lkh@xmath3 264 a , and 0.0230.23 m@xmath2 for lkh@xmath3 262 . the disk mass found for lkh@xmath3 263 abc is consistent with the 0.0018 m@xmath2 inferred from the scattered light image of the edge - on disk around component c. comparison to earlier @xmath4co line observations indicates co depletion by up to a factor 300 with respect to dark - cloud values . the spectral energy distributions ( sed ) suggest grain growth , possibly to sizes of a few hundred @xmath1 m , but our spatially unresolved data can not rule out opacity as an explanation for the sed shape . our observations show that these t tauri stars are still surrounded by significant reservoirs of cold material at an age of 15 myr . we conclude that the observed differences in disk mass are likely explained by binary separation affecting the initial value . with available accretion rate estimates we find that our data are consistent with theoretical expectations for viscously evolving disks having decreased their masses by @xmath5% .
| 229
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1011.1939
|
we propose distributed algorithms to automatically deploy a team of mobile robots to partition and provide coverage of a non - convex environment . to handle arbitrary non - convex environments , we represent them as graphs . our partitioning and coverage algorithm requires only short - range , unreliable pairwise `` gossip '' communication . the algorithm has two components : ( 1 ) a motion protocol to ensure that neighboring robots communicate at least sporadically , and ( 2 ) a pairwise partitioning rule to update territory ownership when two robots communicate . by studying an appropriate dynamical system on the space of partitions of the graph vertices , we prove that territory ownership converges to a pairwise - optimal partition in finite time . this new equilibrium set represents improved performance over common lloyd - type algorithms . additionally , we detail how our algorithm scales well for large teams in large environments and how the computation can run in anytime with limited resources . finally , we report on large - scale simulations in complex environments and hardware experiments using the player / stage robot control system .
| 192
|
0911.4625
|
a new framework for formulating reachability problems with competing inputs , nonlinear dynamics and state constraints as optimal control problems is developed . such reach - avoid problems arise in , among others , the study of safety problems in hybrid systems . earlier approaches to reach - avoid computations are either restricted to linear systems , or face numerical difficulties due to possible discontinuities in the hamiltonian of the optimal control problem . the main advantage of the approach proposed in this paper is that it can be applied to a general class of target hitting continuous dynamic games with nonlinear dynamics , and has very good properties in terms of its numerical solution , since the value function and the hamiltonian of the system are both continuous . the performance of the proposed method is demonstrated by applying it to a two aircraft collision avoidance scenario under target window constraints and in the presence of wind disturbance . target windows are a novel concept in air traffic management , and represent spatial and temporal constraints , that the aircraft have to respect to meet their schedule .
| 189
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1201.3965
|
we numerically investigate the mechanical properties of static packings of ellipsoidal particles in 2d and 3d over a range of aspect ratio and compression @xmath0 . while amorphous packings of spherical particles at jamming onset ( @xmath1 ) are isostatic and possess the minimum contact number @xmath2 required for them to be collectively jammed , amorphous packings of ellipsoidal particles generally possess fewer contacts than expected for collective jamming ( @xmath3 ) from naive counting arguments , which assume that all contacts give rise to linearly independent constraints on interparticle separations . to understand this behavior , we decompose the dynamical matrix @xmath4 for static packings of ellipsoidal particles into two important components : the stiffness @xmath5 and stress @xmath6 matrices . we find that the stiffness matrix possesses @xmath7 eigenmodes @xmath8 with zero eigenvalues even at finite compression , where @xmath9 is the number of particles . in addition , these modes @xmath8 are nearly eigenvectors of the dynamical matrix with eigenvalues that scale as @xmath0 , and thus finite compression stabilizes packings of ellipsoidal particles . at jamming onset , the harmonic response of static packings of ellipsoidal particles vanishes , and the total potential energy scales as @xmath10 for perturbations by amplitude @xmath11 along these ` quartic ' modes , @xmath8 . these findings illustrate the significant differences between static packings of spherical and ellipsoidal particles .
| 230
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1404.0650
|
among type ia supernovae ( sne ia ) exist a class of overluminous objects whose ejecta mass is inferred to be larger than the canonical chandrasekhar mass . we present and discuss the uv / optical photometric light curves , colors , absolute magnitudes , and spectra of three candidate super - chandrasekhar mass sne2009dc , 2011aa , and 2012dn observed with the _ swift _ ultraviolet / optical telescope . the light curves are at the broad end for sne ia , with the light curves of sn 2011aa being amongst the broadest ever observed . we find all three to have very blue colors which may provide a means of excluding these overluminous sne from cosmological analysis , though there is some overlap with the bluest of `` normal '' sne ia . all three are overluminous in their uv absolute magnitudes compared to normal and broad sne ia , but sne 2011aa and 2012dn are not optically overluminous compared to normal sne ia . the integrated luminosity curves of sne 2011aa and 2012dn in the uvot range ( 1600 - 6000 ) are only half as bright as sn 2009dc , implying a smaller @xmath0ni yield . while not enough to strongly affect the bolometric flux , the early time mid - uv flux makes a significant contribution at early times . the strong spectral features in the mid - uv spectra of sne 2009dc and 2012dn suggest a higher temperature and lower opacity to be the cause of the uv excess rather than a hot , smooth blackbody from shock interaction . further work is needed to determine the ejecta and @xmath0ni masses of sne 2011aa and 2012dn and fully explain their high uv luminosities .
| 290
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cond-mat9903407
|
we have measured an angle dependent contribution to the equilibrium magnetization of a yba@xmath0cu@xmath1o@xmath2 single crystal with columnar defects created by irradiation with 5.8 gev pb ions . this contribution manifests itself as a jump in the equilibrium torque signal , when the magnetic field direction crosses that of the defects . the magnitude of the jump , which is observed in a narrow temperature interval of less than 2 k wide , for fields up to about twice the dose equivalent field @xmath3 , is used to estimate the energy gained by vortex pinning on the defects . the vanishing of the effective pinning energy at a temperature below @xmath4 is attributed to its renormalization by thermal fluctuations . 2
| 121
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1404.2625
|
during the last years some interesting experimental results have been reported for experiments in n@xmath0o , no , no dimer , h@xmath0 , toluene and bafch@xmath1 cluster . the main result consists in the observation of molecular beam depletion when the molecules of a pulsed beam interact with a static electric or magnetic field and an oscillating field ( rf ) . in these cases , and as a main difference , instead of using four fields as in the original technique developed by i.i . rabi and others , only two fields , those which configure the resonant unit , are used . that is , without using the non - homogeneous magnetic fields . the depletion explanation for i.i . rabi and others is based in the interaction between the molecular electric or magnetic dipole moment and the non - homogeneous fields . but , obviously , the change in the molecules trajectories observed on these new experiments has to be explained without considering the force provided by the field gradient because it happens without using non - homogeneous fields . in this paper a theoretical way for the explanation of these new experimental results is presented . one important point emerges as a result of this development , namely , the existence of an until now unknown , spin - dependent force , which would be responsible of the aforementioned deviation of the molecules .
| 238
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1608.06229
|
metrics derived from twitter and other social media often referred to as altmetrics are increasingly used to estimate the broader social impacts of scholarship . such efforts , however , may produce highly misleading results , as the entities that participate in conversations about science on these platforms are largely unknown . for instance , if altmetric activities are generated mainly by scientists , does it really capture broader social impacts of science ? here we present a systematic approach to identifying and analyzing scientists on twitter . our method can be easily adapted to identify other stakeholder groups in science . we investigate the demographics , sharing behaviors , and interconnectivity of the identified scientists . our work contributes to the literature both methodologically and conceptually we provide new methods for disambiguating and identifying particular actors on social media and describing the behaviors of scientists , thus providing foundational information for the construction and use of indicators on the basis of social media metrics .
| 166
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1609.02732
|
in the near future , a major challenge in quantum computing is to scale up robust qubit prototypes to practical problem sizes and to implement comprehensive error correction for computational precision . due to inevitable quantum uncertainties in resonant control pulses , increasing the precision of quantum gates comes with the expense of increased energy consumption . consequently , the power dissipated in the vicinity of the processor in a well - working large - scale quantum computer seems unacceptably large in typical systems requiring low operation temperatures . here , we introduce a method for qubit driving and show that it serves to decrease the single - qubit gate error without increasing the average power dissipated per gate . previously , single - qubit gate error induced by a bosonic drive mode has been considered to be inversely proportional to the energy of the control pulse , but we circumvent this bound by reusing and correcting itinerant control pulses . thus our work suggests that heat dissipation does not pose a fundamental limitation , but a necessary practical challenge in future implementations of large - scale quantum computers .
| 190
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1606.08614
|
the zeeman splitting of the conduction band in the hgte quantum wells both with normal and inverted spectrum has been studied experimentally in a wide electron density range . the simultaneous analysis of the sdh oscillations in low magnetic fields at different tilt angles and of the shape of the oscillations in moderate magnetic fields gives a possibility to find the ratio of the zeeman splitting to the orbital one and anisotropy of @xmath0-factor . it is shown that the ratios of the zeeman splitting to the orbital one are close to each other for both types of structures , with a normal and inverted spectrum and they are close enough to the values calculated within _ kp _ method . in contrast , the values of @xmath0-factor anisotropy in the structures with normal and inverted spectra is strongly different and for both cases differs significantly from the calculated ones . we believe that such disagreement with calculations is a result of the interface inversion asymmetry in the hgte quantum well , which is not taken into account in the _ kp _ calculations .
| 185
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1001.4384
|
recently in ( phys . rev . d 76 , 087502 ( 2007 ) and phys . rev . d 77 , 089903(e ) ( 2008 ) ) a thin - shell wormhole has been introduced in 5-dimensional einstein - maxwell - gauss - bonnet ( emgb ) gravity which was supported by normal matter . we wish to consider this solution and investigate its stability . our analysis shows that for the gauss - bonnet ( gb ) parameter @xmath0 stability regions form for a narrow band of finely - tuned mass and charge . for the case @xmath1 , we iterate once more that no stable , normal matter thin - shell wormhole exists .
| 117
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cond-mat0406375
|
motivated by recent suggestions to split the electron - electron interaction into a short - range part , to be treated within the density functional theory , and a long - range part , to be handled by other techniques we compute , with a diffusion monte carlo method , the ground - state energy of a uniform electron gas with a modified , short - range - only electron - electron interaction @xmath0 , for different values of the cutoff parameter @xmath1 and of the electron density . after deriving some exact limits , we propose an analytic representation of the correlation energy which accurately fits our monte carlo data and also includes , by construction , these exact limits , thus providing a reliable `` short - range local - density functional '' .
| 136
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gr-qc0703019
|
it can be shown that in the bpp model the smooth phase transition from the asymptotically decelerated ads universe to the asymptotically accelerated ds universe is possible by solving the modified semiclassical equations of motion . this transition comes from noncommutative poisson algebra , which gives the constant curvature scalars asymptotically . the decelerated expansion of the early universe is due to the negative energy density with the negative pressure induced by quantum back reaction , and the accelerated late - time universe comes from the positive energy and the negative pressure which behave like dark energy source in recent cosmological models .
| 103
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astro-ph0510621
|
spectra have been obtained with the infrared spectrograph on the spitzer space telescope for 18 optically faint sources ( @xmath0 @xmath1 23.9mag ) having f@xmath2 ( 24@xmath3 m ) @xmath4 1.0mjy and having radio detections at 20 cm to a limit of 115@xmath3jy . sources are within the spitzer first look survey . redshifts are determined for 14 sources from strong silicate absorption features ( 12 sources ) or strong pah emission features ( 2 sources ) , with median redshift of 2.1 . results confirm that optically faint sources of @xmath51 mjy at 24@xmath3 m are typically at redshifts z @xmath5 2 , verifying the high efficiency in selecting high redshift sources based on extreme infrared to optical flux ratio , and indicate that 24@xmath3 m sources which also have radio counterparts are not systematically different than samples chosen only by their infrared to optical flux ratios . using the parameter q = log@xmath6f@xmath2(24 @xmath3m)@xmath7f@xmath2(20 cm)@xmath8 $ ] , 17 of the 18 sources observed have values of 0@xmath9q@xmath91 , in the range expected for starburst - powered sources , but only a few of these show strong pah emission as expected from starbursts , with the remainder showing absorbed or power - law spectra consistent with an agn luminosity source . this confirms previous indications that optically faint spitzer sources with f@xmath2(24@xmath3 m ) @xmath1 1.0mjy are predominately agn and represent the upper end of the luminosity function of dusty sources at z @xmath5 2 . based on the characteristics of the sources observed so far , we predict that the nature of sources selected at 24@xmath3 m will change for f@xmath2(24@xmath3 m ) @xmath10 0.5mjy to sources dominated primarily by starbursts .
| 285
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0710.1312
|
we propose a new notation for the states in some models of quantum gravity , namely 4-valent spin networks embedded in a topological three manifold . with the help of this notation , equivalence moves , namely translations and rotations , can be defined , which relate the projections of diffeomorphic embeddings of a spin network . certain types of topological structures , viz 3-strand braids as local excitations of embedded spin networks , are defined and classified by means of the equivalence moves . this paper formulates a mathematical approach to the further research of particle - like excitations in quantum gravity . = 1
| 106
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1006.3910
|
a brief review of the nanoscale free - electron model of metal nanowires is presented . this continuum description of metal nanostructures allows for a unified treatment of cohesive and conducting properties . conductance channels act as delocalized chemical bonds whose breaking is responsible for jumps in the conductance and force oscillations . it is argued that surface and quantum - size effects are the two dominant factors in the energetics of a nanowire , and much of the phenomenology of nanowire stability and structural dynamics can be understood based on the interplay of these two competing factors . a linear stability analysis reveals a sequence of `` magic '' conductance values for which the underlying nanowire geometry is exceptionally stable . the stable configurations include jahn - teller deformed wires of broken axial symmetry . the model naturally explains the experimentally observed shell and supershell structures .
| 148
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cond-mat0103353
|
we perform molecular dynamics simulations on an interacting electron gas confined to a cylindrical surface and subject to a radial magnetic field and the field of the positive background . in order to study the system at lowest energy states that still carry a current , initial configurations are obtained by a special quenching procedure . we observe the formation of a steady state in which the entire electron - lattice cycles with a common uniform velocity . certain runs show an intermediate instability leading to lattice rearrangements . a hall resistance can be defined and depends linearly on the magnetic field with an anomalous coefficient reflecting the manybody contributions peculiar to two dimensions .
| 115
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1306.2714
|
we discuss the generalized second law ( gsl ) and the constraints imposed by it for two types of friedmann universes . the first one is the friedmann universe with radiation and a positive cosmological constant , and the second one consists of non - relativistic matter and a positive cosmological constant . the time evolution of the event horizon entropy and the entropy of the contents within the horizon are analyses in an analytical way by obtaining the hubble parameter . it is shown that the gsl constraint the temperature of both the radiation and matter of the friedmann universe . it is also shown that , even though the net entropy of the radiation ( or matter ) is decreasing at sufficiently large times as the universe expand , it exhibit an increase during the early times when universe is decelerating . that is the entropy of the radiation within the comoving volume is decreasing only when the universe has got an event horizon . keywords : friedmann universe , entropy , generalised second law . pacs : 04.70.dy,97.60lf,98.80jk,02.60jh,04.20cv
| 181
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gr-qc0506059
|
the laser interferometer space antenna ( lisa ) is expected to simultaneously detect many thousands of low frequency gravitational wave signals . this presents a data analysis challenge that is very different to the one encountered in ground based gravitational wave astronomy . lisa data analysis requires the identification of individual signals from a data stream containing an unknown number of overlapping signals . because of the signal overlaps , a global fit to all the signals has to be performed in order to avoid biasing the solution . however , performing such a global fit requires the exploration of an enormous parameter space with a dimension upwards of 50,000 . markov chain monte carlo ( mcmc ) methods offer a very promising solution to the lisa data analysis problem . mcmc algorithms are able to efficiently explore large parameter spaces , simultaneously providing parameter estimates , error analysis , and even model selection . here we present the first application of mcmc methods to simulated lisa data and demonstrate the great potential of the mcmc approach . our implementation uses a generalized f - statistic to evaluate the likelihoods , and simulated annealing to speed convergence of the markov chains . as a final step we super - cool the chains to extract maximum likelihood estimates , and estimates of the bayes factors for competing models . we find that the mcmc approach is able to correctly identify the number of signals present , extract the source parameters , and return error estimates consistent with fisher information matrix predictions .
| 261
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1504.01234
|
in the single degenerate ( sd ) scenario of type ia supernovae ( sne ia ) , the collision of the ejecta with its companion results in stripping hydrogen rich matter from the companion star . this hydrogen rich matter might leave its trace in the light curves and/or spectra . in this paper , we perform radiation hydrodynamical simulations of this collision for three binary systems . as a result , we find that the emission from the shock - heated region is not as strong as in the previous study . this weak emission , however , may be a result of our underestimate of the coupling between the gas and radiation in the shock interaction . therefore , though our results suggest that the observed early light curves of sne ia can not rule out binary systems with a short separation as the progenitor system , more elaborate numerical studies will be needed to reach a fair conclusion . alternatively , our results indicate that the feature observed in the early phase of a recent type ia sn 2014j might result from interaction of the ejecta with a red giant companion star . we also discuss the dependence of spectral features of h@xmath0 and si ii absorption lines on viewing angles and investigate whether they can constrain the event rate of the sd progenitor .
| 228
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cond-mat0008283
|
a random distribution of inert sites is introduced in the ziff - gulari - barshad model to study the phase transitions between active and poisoned states . the adsorption of @xmath0 and @xmath1 molecules is not possible at the position of the inert sites . this model is investigated in the site and pair approximations , as well as through monte carlo simulations . we determine the mean coverages of the elements as a function of the dilution and show that the continuous transition between the active and o - poisoned state is slightly affected by moderate values of dilution in the pair approximation and in the simulations . on the other hand , from the analysis of the hysteresis curves , the transition between the active and co - poisoned states changes from first - order to continuous as one increases the concentration of inactive sites . the observed transition in the site and pair approximations is always of first - order nature . we also found the lines of transition and spinodal points as a function of the concentration of inert sites . finally , the production rate of @xmath2 is calculated as a function of the dilution of sites . pacs number(s ) : 05.70.ln , 05.70.fh , 82.65.jv , 82.20.mj
| 214
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1608.04150
|
the gaia satellite will provide unprecedented phase - space information for our galaxy and enable a new era of galactic dynamics . we may soon see successful realizations of galactoseismology , i.e. , inferring the characteristics of the galactic potential and sub - structure from a dynamical analysis of observed perturbations in the gas or stellar disk of the milky way . here , we argue that to maximally take advantage of the gaia data and other complementary surveys , it is necessary to build comprehensive models for both the stars and the gas . we outline several key morphological puzzles of the galactic disk and proposed solutions that may soon be tested .
| 114
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1105.6220
|
we investigate the hydrodynamic limit for weakly asymmetric simple exclusion processes in crystal lattices . we construct a suitable scaling limit by using a discrete harmonic map . as we shall observe , the quasi - linear parabolic equation in the limit is defined on a flat torus and depends on both the local structure of the crystal lattice and the discrete harmonic map . we formulate the local ergodic theorem on the crystal lattice by introducing the notion of local function bundle , which is a family of local functions on the configuration space . the ideas and methods are taken from the discrete geometric analysis to these problems . results we obtain are extensions of ones by kipnis , olla and varadhan to crystal lattices .
| 128
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1009.6155
|
we study the continuous - variable quantum teleportation of states , statistical moments of observables , and scale parameters such as squeezing . we investigate the problem both in ideal and imperfect vaidman - braunstein - kimble protocol setups . we show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources . specifically , we consider the teleportation of coherent squeezed states , exploiting squeezed bell states as entangled resources . this class of non - gaussian states , introduced in references @xcite , includes photon - added and photon - subtracted squeezed states as special cases . at variance with the case of entangled gaussian resources , the use of entangled non - gaussian squeezed bell resources allows one to choose different optimization procedures that lead to inequivalent results . performing two independent optimization procedures one can either maximize the state teleportation fidelity , or minimize the difference between input and output quadrature variances the two different procedures are compared depending on the degrees of displacement and squeezing of the input states and on the working conditions in ideal and non - ideal setups .
| 199
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1101.3783
|
geometrically thick accretion flows may be present in black hole x - ray binaries observed in the low / hard state and in low - luminosity active galactic nuclei . unlike in geometrically thin disks , the angular momentum axis in these sources is not expected to align with the black hole spin axis . we compute images from three - dimensional general relativistic magnetohydrodynamic simulations of misaligned ( tilted ) accretion flows using relativistic radiative transfer , and compare the estimated locations of the radiation edge with expectations from their aligned ( untilted ) counterparts . the radiation edge in the tilted simulations is independent of black hole spin for a tilt of @xmath0 , in stark contrast to the results for untilted simulations , which agree with the monotonic dependence on spin expected from thin accretion disk theory . synthetic emission line profiles from the tilted simulations depend strongly on the observer s azimuth , and exhibit unique features such as broad blue wings . " coupled with precession , the azimuthal variation could generate time fluctuations in observed emission lines , which would be a clear `` signature '' of a tilted accretion flow . finally , we evaluate the possibility that the observed low- and high - frequency quasi - periodic oscillations ( qpos ) from black hole binaries could be produced by misaligned accretion flows . although low - frequency qpos from precessing , tilted disks remains a viable option , we find little evidence for significant power in our light curves in the frequency range of high - frequency qpos .
| 267
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1602.07544
|
we present a survey for transient and variable sources , on timescales from 28 seconds to @xmath01 year , using the murchison widefield array ( mwa ) at 182 mhz . down to a detection threshold of 0.285 jy , no transient candidates were identified , making this the most constraining low - frequency survey to date and placing a limit on the surface density of transients of @xmath1 deg@xmath2 for the shortest timescale considered . at these frequencies , emission from fast radio bursts ( frbs ) is expected to be detectable in the shortest timescale images without any corrections for interstellar or intergalactic dispersion . at an frb limiting flux density of 7980 jy , we find a rate of @xmath382 frbs per sky per day for dispersion measures @xmath3700 pc @xmath4 . assuming a cosmological population of standard candles , our rate limits are consistent with the frb rates obtained by @xcite if they have a flat spectral slope . finally , we conduct an initial variability survey of sources in the field with flux densities @xmath50.5 jy and identify no sources with significant variability in their lightcurves . however , we note that substantial further work is required to fully characterise both the short term and low level variability within this field . [ firstpage ] instrumentation : interferometers - techniques : image processing - catalogues - radio continuum : general
| 235
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1510.04692
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traditional concept of cognitive radio is the coexistence of primary and secondary user in multiplexed manner . we consider the opportunistic channel access scheme in ieee 802.11 based networks subject to the interference mitigation scenario . according to the protocol rule and due to the constraint of message passing , secondary user is unaware of the exact state of the primary user . in this paper , we have proposed an online algorithm for the secondary which assist determining a backoff counter or the decision of being idle for utilizing the time / frequency slot unoccupied by the primary user . proposed algorithm is based on conventional reinforcement learning technique namely q - learning . simulation has been conducted in order to prove the strength of this algorithm and also results have been compared with our contemporary solution of this problem where secondary user is aware of some states of primary user . cognitive radio , ism band , reinforcement learning , optimization , q - learning
| 167
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0809.4265
|
the _ hst _ proper motion ( pm ) measurements of the clouds have severe implications for their interaction history with the milky way ( mw ) and with each other . the clouds are likely on their first passage about the mw and the smc s orbit about the lmc is better described as quasi - periodic rather than circular . binary l / smc orbits that satisfy observational constraints on their mutual interaction history ( e.g. the formation of the magellanic bridge during a collision between the clouds @xmath0300 myr ago ) can be located within 1@xmath1 of the mean pms . however , these binary orbits are not co - located with the magellanic stream ( ms ) when projected on the plane of the sky and the line - of - sight velocity gradient along the lmc s orbit is significantly steeper than that along the ms . these combined results ultimately rule out a purely tidal origin for the ms : tides are ineffective without multiple pericentric passages and can neither decrease the velocity gradient nor explain the offset stream in a polar orbit configuration . alternatively , ram pressure stripping of an extended gaseous disk may naturally explain the deviation . the offset also suggests that observations of the little - explored region between ra 21@xmath2 and 23@xmath2 are crucial for characterizing the full extent of the ms .
| 235
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nucl-th0404028
|
the three - body energy - dependent effective interaction given by the bloch - horowitz ( bh ) equation is evaluated for various shell - model oscillator spaces . the results are applied to the test case of the three - body problem ( @xmath0h and @xmath0he ) , where it is shown that the interaction reproduces the exact binding energy , regardless of the parameterization ( number of oscillator quanta or value of the oscillator parameter @xmath1 ) of the low - energy included space . we demonstrate a non - perturbative technique for summing the excluded - space three - body ladder diagrams , but also show that accurate results can be obtained perturbatively by iterating the two - body ladders . we examine the evolution of the effective two - body and induced three - body terms as @xmath1 and the size of the included space @xmath2 are varied , including the case of a single included shell , @xmath3 . for typical ranges of @xmath1 , the induced effective three - body interaction , essential for giving the exact three - body binding , is found to contribute @xmath410% to the binding energy .
| 198
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1203.6645
|
production in association with an electroweak vector boson @xmath0 is a distinctive mode of production for a higgs boson @xmath1 without tree - level couplings to fermions , known as a fermiophobic higgs boson . we focus on @xmath2 associated production with @xmath1 decay into a pair of photons , and @xmath0 into a pair of jets , with the goal of distinguishing a fermiophobic higgs boson from the standard model higgs boson . performing a simulation of the signal and pertinent qcd backgrounds , and using the same event selection cuts employed by the lhc atlas collaboration , we argue that existing lhc data at 7 tev with 4.9 fb@xmath3 of integrated luminosity may distinguish a fermiophobic higgs boson from a standard model higgs boson near 125 gev at about 1.9 standard deviation signal significance ( @xmath4 ) per experiment . at 8 tev we show that associated production could yield @xmath5 significance per experiment with 10 fb@xmath3 of data .
| 162
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astro-ph0003343
|
we present an analytic model for the fully nonlinear power spectrum @xmath0 and bispectrum @xmath1 of the cosmological mass density field . the model is based on physical properties of dark matter halos , with the three main model inputs being analytic halo density profiles , halo mass functions , and halo - halo spatial correlations , each of which has been well studied in the literature . we demonstrate that this new model can reproduce the power spectrum and bispectrum computed from cosmological simulations of both an @xmath2 scale - free model and a low - density cold dark matter model . to enhance the dynamic range of these large simulations , we use the synthetic halo replacement technique of ma & fry ( 2000 ) , where the original halos with numerically softened cores are replaced by synthetic halos of realistic density profiles . at high wavenumbers , our model predicts a slope for the nonlinear power spectrum different from the often - used fitting formulas in the literature based on the stable clustering assumption . our model also predicts a three - point amplitude @xmath1 that is scale dependent , in contrast to the popular hierarchical clustering assumption . this model provides a rapid way to compute the mass power spectrum and bispectrum over all length scales where the input halo properties are valid . it also provides a physical interpretation of the clustering properties of matter in the universe .
| 244
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1005.3312
|
we compare the position of an ordering transition in a metal to that in a superconductor . for the spin density wave ( sdw ) transition , we find that the quantum critical point shifts by order @xmath0 , where @xmath1 is pairing amplitude , so that the region of sdw order is smaller in the superconductor than in the metal . this shift is larger than the @xmath2 shift predicted by theories of competing orders which ignore fermi surface effects . for ising - nematic order , the shift from fermi surface effects remains of order @xmath3 . we discuss implications of these results for the phase diagrams of the cuprates and the pnictides . we conclude that recent observations imply that the ising - nematic order is tied to the square of the sdw order in the pnictides , but not in the cuprates . = 10000
| 149
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1210.1716
|
the strongly coupled phase of yang - mills plasma with arbitrary gauge group is studied in a @xmath0-matrix approach . the existence of lowest - lying glueballs , interpreted as bound states of two transverse gluons ( quasi - particles in a many - body set up ) , is analyzed in a non - perturbative scattering formalism with the input of lattice - qcd static potentials . glueballs are actually found to be bound up to 1.3 @xmath1 . starting from the @xmath0-matrix , the plasma equation of state is computed by resorting to dashen , ma and bernstein s formulation of statistical mechanics and favorably compared to quenched lattice data . special emphasis is put on su(@xmath2 ) gauge groups , for which analytical results can be obtained in the large-@xmath2 limit , and predictions for a @xmath3 gauge group are also given within this work .
| 149
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astro-ph0006392
|
we emphasize that the estimation of cosmological parameters from cosmic microwave background ( cmb ) anisotropy data , such as the recent high resolution maps from boomerang and maxima-1 , requires assumptions about the primordial spectra . the latter are predicted from inflation . the physically best - motivated scenario is that of slow - roll inflation . however , very often , the unphysical power - law inflation scenario is ( implicitly ) assumed in the cmb data analysis . we show that the predicted multipole moments differ significantly in both cases . we identify several misconceptions present in the literature ( and in the way inflationary relations are often combined in popular numerical codes ) . for example , we do not believe that , generically , inflation predicts the relation @xmath0 for the spectral indices of scalar and tensor perturbations or that gravitational waves are negligible . we calculate the cmb multipole moments for various values of the slow - roll parameters and demonstrate that an important part of the space of parameters @xmath1 has been overlooked in the cmb data analysis so far .
| 188
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astro-ph9705073
|
in this paper we show the results of a large set of @xmath0-body simulations modelling the evolution of globular clusters driven by relaxation , stellar evolution , disk shocking and including the effects of the tidal field of the galaxy . we investigate the evolution of multi - mass models with a power - law initial mass function ( imf ) starting with different initial masses , concentrations , slopes of the imf and located at different galactocentric distances . we show to what extent the effects of the various evolutionary processes alter the shape of the imf and to what extent these changes depend on the position of the cluster in the galaxy . both the changes in the global mass function and in the local one ( measured at different distances from the cluster center ) are investigated showing whether and where the local mass function keeps memory of the imf and where it provides a good indication of the current global mass function . the evolution of the population of white dwarfs is also followed in detail and we supply an estimate of the fraction of the current value of the total mass expected to be in white dwarfs depending on the main initial conditions for the cluster ( mass and position in the galaxy ) . simple analytical expression by which it is possible to calculate the main quantities of interest ( total mass , fraction of white dwarfs , slope of the mass function ) at any time @xmath1 for a larger number of different initial conditions than those investigated numerically have been derived . 6ngc 6397 globular clusters : general stellar dynamics
| 278
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astro-ph0601506
|
we report on eso very large telescope optical spectroscopy of 42 bl lacertae objects of unknown redshift . nuclear emission lines were observed in 12 objects , while for another six we detected absorption features due to their host galaxy . the new high s / n spectra therefore allow us to measure the redshift of 18 sources . five of the observed objects were reclassified either as stars or quasars , and one is of uncertain nature . for the remaining 18 the optical spectra appear without intrinsic features in spite of our ability to measure rather faint ( ew @xmath00.1 ) spectral lines . for the latter sources a lower limit to the redshift was set exploiting the very fact that the absorption lines of the host galaxy are undetected on the observed spectra .
| 137
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1006.2324
|
we consider self - localization of a small number of bose particles immersed in a large homogeneous superfluid mixture of fermions in three and one dimensional spaces . bosons distort the density of surrounding fermions and create a potential well where they can form a bound state analogous to a small polaron state . in the three dimensional volume we observe the self - localization for repulsive interactions between bosons and fermions . in the one dimensional case bosons self - localize as well as for attractive interactions forming , together with a pair of fermions at the bottom of the fermi sea , a vector soliton . we analyze also thermal effects and show that small non - zero temperature affects the pairing function of the fermi - subsystem and has little influence on the self - localization phenomena .
| 141
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1111.4433
|
we analyze continuous - time quantum walks on necklace graphs cyclical graphs consisting of many copies of a smaller graph ( pearl ) . using a bloch - type ansatz for the eigenfunctions , we block - diagonalize the hamiltonian , reducing the effective size of the problem to the size of a single pearl . we then present a general approach for showing that the mixing time scales ( with growing size of the necklace ) similarly to that of a simple walk on a cycle . finally , we present results for mixing on several necklace graphs .
| 100
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1307.5338
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we present _ hubble space telescope _ ( _ hst _ ) observations of the exceptionally bright and luminous _ swift _ gamma - ray burst , grb 130427a . at @xmath0 this burst affords an excellent opportunity to study the supernova and host galaxy associated with an intrinsically extremely luminous burst ( @xmath1 erg ) : more luminous than any previous grb with a spectroscopically associated supernova . we use the combination of the image quality , uv capability and and invariant psf of _ hst _ to provide the best possible separation of the afterglow , host and supernova contributions to the observed light @xmath217 rest - frame days after the burst utilising a host subtraction spectrum obtained 1 year later . acs grism observations show that the associated supernova , sn 2013cq , has an overall spectral shape and luminosity similar to sn 1998bw ( with a photospheric velocity , @xmath3 km s@xmath4 ) . the positions of the bluer features are better matched by the higher velocity sn 2010bh ( @xmath5 km s@xmath4 ) , but this sn is significantly fainter , and fails to reproduce the overall spectral shape , perhaps indicative of velocity structure in the ejecta . we find that the burst originated @xmath24 kpc from the nucleus of a moderately star forming ( 1 m@xmath6 yr@xmath4 ) , possibly interacting disc galaxy . the absolute magnitude , physical size and morphology of this galaxy , as well as the location of the grb within it are also strikingly similar to those of grb980425/sn 1998bw . the similarity of supernovae and environment from both the most luminous and least luminous grbs suggests broadly similar progenitor stars can create grbs across six orders of magnitude in isotropic energy .
| 295
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1701.02760
|
the fiber g - ratio is the ratio of the inner to the outer diameter of the myelin sheath of a myelinated axon . it has a limited dynamic range in healthy white matter , as it is optimized for speed of signal conduction , cellular energetics , and spatial constraints . _ in vivo _ imaging of the g - ratio in health and disease would greatly increase our knowledge of the nervous system and our ability to diagnose , monitor , and treat disease . mri based g - ratio imaging was first conceived in 2011 , and expanded to be feasible in full brain with preliminary results in 2013 . this manuscript reviews the growing g - ratio imaging literature and speculates on future applications . it details the methodology for imaging the g - ratio with mri , and describes the known pitfalls and challenges in doing so . g - ratio , mri , myelin imaging , diffusion mri , white matter , microstructure
| 169
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1410.5501
|
we carry out an explicit calculation of the vacuum polarization tensor for an effective low - energy model of monolayer graphene in the presence of a weak magnetic field of intensity @xmath0 perpendicularly aligned to the membrane . by expanding the quasiparticle propagator in the schwinger proper time representation up to order @xmath1 , where @xmath2 is the unit charge , we find an explicitly transverse tensor , consistent with gauge invariance . furthermore , assuming that graphene is radiated with monochromatic light of frequency @xmath3 along the external field direction , from the modified maxwell s equations we derive the intensity of transmitted light and the angle of polarization rotation in terms of the longitudinal ( @xmath4 ) and transverse ( @xmath5 ) conductivities . corrections to these quantities , both calculated and measured , are of order @xmath6 . our findings generalize and complement previously known results reported in literature regarding the light absorption problem in graphene from the experimental and theoretical points of view , with and without external magnetic fields .
| 175
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astro-ph0012252
|
we have investigated the ram - pressure stripping of disk galaxies in clusters at various redshifts and in cluster progenitors ; the clusters grow up on a hierarchical clustering scenario . we consider a radially infalling galaxy whose initial position and velocity are given by a spherical collapse model of structure formation . moreover , since observations show that the intracluster medium ( icm ) of nearby clusters is non - gravitationally heated , we study the effect of the non - gravitational heating on the ram - pressure stripping . for a given redshift , we find that ram - pressure stripping has more influence on galaxies in more massive clusters . on the other hand , for a given mass , it has more influence on galaxies in the clusters at higher redshifts . in particular , we predict that in rich clusters at @xmath0 , most of the galaxies are affected by the ram - pressure stripping . while the non - gravitational heating significantly reduces the influence of ram - pressure stripping on galaxies in clusters with mass smaller than @xmath1 , it does not affect the influence in richer clusters . if the icm is heated non - gravitationally at @xmath2 , ram - pressure stripping does not occur at @xmath3 in the progenitors of clusters observed at @xmath4 , because the heat makes the icm fraction of the cluster progenitors small . on the other hand , if the icm is heated non - gravitationally at @xmath5 for the first time , the ram - pressure stripping occurs even at @xmath6 . we compare the results with the observations of galaxies in clusters at various redshifts .
| 283
|
1309.0933
|
we argue that geometrical scaling ( gs ) proposed originally in the context of deep inelastic scattering ( dis ) at hera works also in pp collisions at the lhc energies and in na61/shine experiment . we show that in dis gs is working up to relatively large bjorken @xmath0 . as a consequence negative pion multiplicity @xmath1 distributions at na61/shine energies exhibit gs in mid rapidity region . for @xmath2 clear sign of scaling violations can be seen when one of the colliding partons has bjorken @xmath3 . finally , we argue that in the case of identified particles gs scaling is still present but the scaling variable is a function of transverse mass rather than @xmath1 . + + pacs number(s ) : 13.85.ni,12.38.lg
| 126
|
cond-mat0606715
|
we calculate the distribution of the conductance @xmath0 in a one - dimensional disordered wire at finite temperature @xmath1 and bias voltage @xmath2 in a independent - electron picture and assuming full coherent transport . at high enough temperature and bias voltage , where several resonances of the system contribute to the conductance , the distribution @xmath3 can be represented with good accuracy by autoconvolutions of the distribution of the conductance at zero temperature and zero bias voltage . the number of convolutions depends on @xmath1 and @xmath2 . in the regime of very low @xmath1 and @xmath2 , where only one resonance is relevant to @xmath4 , the conductance distribution is analyzed by a resonant tunneling conductance model . strong effects of finite @xmath1 and @xmath2 on the conductance distribution are observed and well described by our theoretical analysis , as we verify by performing a number of numerical simulations of a one - dimensional disordered wire at different temperatures , voltages , and lengths of the wire . analytical estimates for the first moments of @xmath3 at high temperature and bias voltage are also provided .
| 188
|
1701.03300
|
the pilot system development in metre - scale negative laboratory discharges is studied with ns - fast photography . the systems appear as bipolar structures in the vicinity of the negative high - voltage electrode . they appear as a result of a single negative streamer propagation and determine further discharge development . such systems possess features like glowing beads , bipolarity , different brightness of the top and bottom parts , and mutual reconnection . a 1d model of the ionization evolution in the spark gap is proposed . in the process of the nonlinear development of ionization growth , the model shows features similar to those observed . the visual similarities between high - altitude sprites and laboratory pilots are striking and may indicate that they are two manifestations of the same natural phenomenon . version of +
| 140
|
0908.4332
|
the understanding of the accretion process on to compact objects in binary systems is an important part of modern astrophysics . theoretical work , primarily that of ghosh & lamb ( 1979 ) , has made clear predictions for the behaviour of such systems which have been generally supported by observational results of considerably varying quality from galactic accreting pulsar systems . in this work a much larger homogeneous population of such objects in the small magellanic cloud ( smc ) is used to provide more demanding tests of the accretion theory . the results are extremely supportive of the theoretical models and provide useful statistical insights into the manner in which accreting pulsars behave and evolve . [ firstpage ] stars : neutron - x - rays : binaries
| 130
|
1508.05009
|
we study the star formation history for a sample of 154 galaxies with stellar mass @xmath0 in the redshift range @xmath1 . we do this using stellar population models combined with full - spectrum fitting of good quality spectra and high resolution photometry . for a subset of 68 galaxies ( @xmath2 ) we additionally construct dynamical models . these use an axisymmetric solution to the jeans equations , which allows for velocity anisotropy , and adopts results from abundance matching techniques to account for the dark matter content . we find that : ( i ) the trends in star formation history observed in the local universe are already in place by @xmath3 : the most massive galaxies are already passive , while lower mass ones have a more extended star formation histories , and the lowest mass galaxies are actively forming stars ; ( ii ) we place an upper limit of a factor 1.5 to the size growth of the massive galaxy population ; ( iii ) we present strong evidence for low dark matter fractions within 1 ( median of 9 per cent and 90th percentile of 21 per cent ) for galaxies with @xmath4 at these redshifts ; and ( iv ) we confirm that these galaxies have , on average , a salpeter normalisation of the stellar initial mass function . [ firstpage ] galaxies : evolution - galaxies : formation - galaxies : stellar content - galaxies : haloes - galaxies : high redshift
| 251
|
0711.4964
|
in various astronomical projects it is crucial to have coordinates indexed tables . all sky optical and ir catalogues have up to 1 billion objects that will increase with forthcoming projects . also partial sky surveys at various wavelengths can collect information ( not just source lists ) which can be saved in coordinate ordered tables . selecting a sub - set of these entries or cross - matching them could be un - feasible if no indexing is performed . sky tessellation with various mapping functions have been proposed . it is a matter of fact that the astronomical community is accepting the htm and healpix schema as the default for object catalogues and for maps visualization and analysis , respectively . within the mcs library project , we have now made available as mysql - callable functions various htm and healpix facilities . this is made possible thanks to the capability offered by mysql 5.1 to add external plug - ins . the dif ( dynamic indexing facilities ) package distributed within the mcs library , creates and manages a combination of views , triggers , db - engine and plug - ins allowing the user to deal with database tables indexed using one or both these pixelisation schema in a completely transparent way .
| 217
|
nucl-th9612001
|
the quark - meson coupling model , based on a mean - field description of non - overlapping nucleon bags bound by the self - consistent exchange of @xmath0 , @xmath1 and @xmath2 mesons , is extended to investigate the change of hadron properties in finite nuclei . relativistic hartree equations for spherical nuclei have been derived from a relativistic quark model of the structure of bound nucleons and mesons . using this unified , self - consistent description of both infinite nuclear matter and finite nuclei , we investigate the properties of some closed - shell nuclei , and study the changes in the hadron masses of the non - strange vector mesons , the hyperons and the nucleon in those nuclei . we find a new , simple scaling relation for the changes of the hadron masses , which can be described in terms of the number of non - strange quarks in the hadron and the value of the scalar mean - field in a nucleus . = 0 cm = 0 cm = 0 cm = 23 cm = 16 cm adp-96 - 40/t236 variation of hadron masses in finite nuclei k. saito + physics division , tohoku college of pharmacy + sendai 981 , japan + k. tsushima and a. w. thomas + department of physics and mathematical physics + university of adelaide , south australia , 5005 , australia pacs numbers : 12.39.ba , 21.60.-n , 21.90.+f , 24.85.+p
| 245
|
0706.1265
|
most vega - like stars have far - infrared excess ( 60@xmath0 or longward in _ iras , iso , or spitzer mips _ bands ) and contain cold dust ( @xmath1150k ) analogous to the sun s kuiper - belt region . however , dust in a region more akin to our asteroid belt and thus relevant to the terrestrial planet building process is warm and produces excess emission in mid - infrared wavelengths . by cross - correlating hipparcos dwarfs with the msx catalog , we found that ef cha , a member of the recently identified , @xmath210myr old , `` cha - near '' moving group , possesses prominent mid - infrared excess . n - band spectroscopy reveals a strong emission feature characterized by a mixture of small , warm , amorphous and possibly crystalline silicate grains . survival time of warm dust grains around this a9 star is @xmath3 yrs , much less than the age of the star . thus , grains in this extra - solar terrestrial planetary zone must be of `` second generation '' and not a remnant of primodial dust and are suggestive of substantial planet formation activity . such second generation warm excess occurs around @xmath2 13% of the early - type stars in nearby young stellar associations .
| 221
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1603.09216
|
we consider the nonlinear scattering theory for three - terminal thermoelectric devices , used for power generation or refrigeration . such a system is a quantum phase - coherent version of a thermocouple , and the theory applies to systems in which interactions can be treated at a mean - field level . we consider an arbitrary three - terminal system in any external magnetic field , including systems with broken time - reversal symmetry , such as chiral thermoelectrics , as well as systems in which the magnetic field plays no role . we show that the upper bound on efficiency at given power output is of quantum origin and is stricter than carnot s bound . the bound is exactly the same as previously found for two - terminal devices , and can be achieved by three - terminal systems with or without broken time - reversal symmetry . thus the bound appears to be universal for two - terminal and three - terminal ( chiral and non - chiral ) thermoelectrics . -25 mm ( a ) the three - terminal machine ( heat - engine or refrigerator ) that we consider , the exchange of electrons with reservoir m carries a heat current , @xmath0 , but not an electrical current , @xmath1 . ( b ) a chiral thermoelectric device reproduced from ref . [ ] . ( c ) a system in which photons deliver the heat , this can be phenomenologically modelled by ( a ) , see section [ sect : voltage - probe ] . , title="fig : " ] @xmath2
| 270
|
astro-ph0207187
|
grb 010921 was the first hete-2 grb to be localized via its afterglow emission . the low - redshift of the host galaxy , @xmath0 , prompted us to undertake intensive multi - color observations with the _ hubble space telescope _ with the goal of searching for an underlying supernova component . we do not detect any coincident supernova to a limit 1.34 mag fainter than sn 1998bw at 99.7% confidence , making this one of the most sensitive searches for an underlying sn . analysis of the afterglow data allow us to infer that the grb was situated behind a net extinction ( milky way and the host galaxy ) of @xmath1 mag in the observer frame . thus , had it not been for such heavy extinction our data would have allowed us to probe for an underlying sn with brightness approaching those of more typical type ib / c supernovae .
| 155
|
1010.4540
|
diffusive properties of a monodisperse system of interacting particles confined to a _ quasi_-one - dimensional ( q1d ) channel are studied using molecular dynamics ( md ) simulations . we calculate numerically the mean - squared displacement ( msd ) and investigate the influence of the width of the channel ( or the strength of the confinement potential ) on diffusion in finite - size channels of different shapes ( i.e. , straight and circular ) . the transition from single - file diffusion ( sfd ) to the two - dimensional diffusion regime is investigated . this transition ( regarding the calculation of the scaling exponent ( @xmath0 ) of the msd @xmath1 @xmath2 ) as a function of the width of the channel , is shown to change depending on the channel s confinement profile . in particular the transition can be either smooth ( i.e. , for a parabolic confinement potential ) or rather sharp / stepwise ( i.e. , for a hard - wall potential ) , as distinct from infinite channels where this transition is abrupt . this result can be explained by qualitatively different distributions of the particle density for the different confinement potentials .
| 202
|
0810.5615
|
we introduce the notion of a _ conjugation - free geometric presentation _ for a fundamental group of a line arrangement s complement , and we show that the fundamental groups of the following family of arrangements have a conjugation - free geometric presentation : a real arrangement @xmath0 , whose graph of multiple points is a union of disjoint cycles , has no line with more than two multiple points , and where the multiplicities of the multiple points are arbitrary . we also compute the exact group structure ( by means of a semi - direct product of groups ) of the arrangement of @xmath1 lines whose graph consists of a cycle of length @xmath2 , and all the multiple points have multiplicity @xmath2 .
| 127
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1303.2630
|
narrow - band spectral imaging with sub - pixel resolution of the _ chandra_-acis archival observation of the ulirg merger arp 220 strongly suggests two compton thick nuclei , spatially coincident with the infrared and radio emitting nuclear clusters , and separated by 1 ( @xmath0 pc at a distance of 76 mpc ) . these previously undetected highly obscured agns - west ( w ) and east ( e ) - are imaged , and separated from neighboring sources , in the 6 - 7 kev band , where the fe - k lines dominate the emission . the western nucleus is also detected at energies above 7 kev . we estimate fe - k equivalent width @xmath1 kev or possibly greater for both sources , and observed 2 - 10 kev luminosities @xmath2 ( w ) and @xmath3 ( e ) . from the observed fe - k lines luminosities , and assuming on the basis of the _ xmm - newton _ spectrum that 40% of this may be from the 6.4 kev component , we evaluate 2 - 10 kev intrinsic luminosities @xmath4 ( w ) and @xmath5 ( e ) . the inferred x - ray luminosity is at least a factor of 3 higher than that expected from a pure starburst with the bolometric luminosity of arp 220 . for a typical agn sed the bolometric luminosities are @xmath6 ( w ) and @xmath7 ( e ) .
| 244
|
1610.03571
|
we reexamine the invariance of two - photon transition matrix elements and corresponding two - photon rabi frequencies under the `` gauge '' transformation from the length to the velocity gauge . it is shown that gauge invariance , in the most general sense , only holds at exact resonance , for both one - color as well as two - color absorption . the arguments leading to this conclusion are supported by analytic calculations which express the matrix elements in terms of hypergeometric functions , and ramified by a `` master identity '' which is fulfilled by off - diagonal matrix elements of the schrdinger propagator under a the transformation from the velocity to the length gauge . the study of the gauge dependence of atomic processes highlights subtle connections between the concept of asymptotic states , the gauge transformation of the wave function , and infinitesimal damping parameters for perturbations and interaction hamiltonians that switch off the terms in the infinite past and future [ of the form @xmath0 . we include a pertinent discussion .
| 178
|
0803.3582
|
we have shown that non - zero @xmath0 is generated in a see - saw type softly broken @xmath1 symmetric model through a single parameter perturbation in @xmath2 in a single element . we have explored all possible 9 cases to study the neutrino mixing angles considering the best fitted values of @xmath3 and @xmath4 with all parameters real . we have extended our analysis for the complex case and demonstrated large low energy cp violation ( @xmath5 ) and @xmath6 in addition to mixing and mass pattern . we have also investigated leptogenesis and for a reasonable choice of model parameters compatible with low energy data , wmap value of baryon asymmetry @xmath7 is obtained for right handed neutrino mass scale @xmath8 gev . we have obtained a relation among the phases responsible for leptogenesis and have shown that those phases also have correlations with low energy cp violating phases . pacs number(s ) : 14.60.pq , 11.30.hv , 98.80.cq
| 161
|
1510.07978
|
constrained density functional theory ( cdft ) is used to evaluate the energy level alignment of a benzene molecule as it approaches a graphene sheet . within cdft the problem is conveniently mapped onto evaluating total energy differences between different charge - separated states , and it does not consist in determining a quasi - particle spectrum . we demonstrate that the simple local density approximation provides a good description of the level aligmnent along the entire binding curve , with excellent agreement to experiments at an infinite separation and to @xmath0 calculations close to the bonding distance . the method also allows us to explore the effects due to the presence of graphene structural defects and of multiple molecules . in general all our results can be reproduced by a classical image charge model taking into account the finite dielectric constant of graphene .
| 145
|
1405.3360
|
this paper studies _ the nash stability _ in hedonic coalition formation games . we address the following issue : for a general problem formulation , is there any utility allocation method ensuring a nash - stable partition ? we propose the definition of _ the nash - stable core _ and we analyze the conditions for having a non - empty nash - stable core . more precisely , we prove that using relaxed efficiency in utility sharing allows to ensure a non empty nash - stable core . then , a decentralized algorithm called _ nash stability establisher _ is proposed for finding the nash stability in a game whenever at least one exists . the problem of finding the nash stability is formulated as a non - cooperative game . in the proposed approach , during each round , each player determines its strategy in its turn according to a _ random round - robin scheduler_. we prove that the algorithm converges to an equilibrium if it exists , which is the indicator of the nash stability .
| 181
|
1211.7319
|
within mean - field theory we calculate the scaling functions associated with critical casimir forces for a system consisting of two spherical colloids immersed in a binary liquid mixture near its consolute point and facing a planar , homogeneous substrate . for several geometrical arrangements and boundary conditions we analyze the normal and the lateral critical casimir forces acting on one of the two colloids . we find interesting features such as a change of sign of these forces upon varying either the position of one of the colloids or the temperature . by subtracting the pairwise forces from the total force we are able to determine the many - body forces acting on one of the colloids . we have found that the many - body contribution to the total critical casimir force is more pronounced for small colloid - colloid and colloid - substrate distances , as well as for temperatures close to criticality , where the many - body contribution to the total force can reach up to @xmath0 .
| 173
|
1110.1368
|
a class of potential backgrounds for higgs boson searches in the @xmath0 channel at both the tevatron and large hadron collider is presented . backgrounds from @xmath1 production with _ external _ conversion of the on - shell photon in detector material to an asymmetric electron positron pair , @xmath2 , with loss of the trailing electron or positron has been treated adequately in higgs searches . here we consider analogous backgrounds from @xmath3 production with _ internal _ conversion of the off - shell photon in vacuum to an asymmetric lepton anti - lepton pair @xmath4 . while the former process yields almost entirely electrons or positrons , the latter can give electron , positron , muon , and anti - muon backgrounds in roughly equal amounts . we estimate that asymmetric internal conversion backgrounds are comparable to the higgs boson signal in the standard signal region of phase space . these processes also represent potential backgrounds for new physics searches in same - sign di - lepton channels . some data driven methods to characterize asymmetric internal conversion backgrounds are suggested . ru - nhetc-2011 - 16 + uttg-20 - 11 + tcc-022 - 11 + 1.0 in * backgrounds to higgs boson searches from * + * @xmath5 asymmetric internal conversion * 0.65 in richard c. gray@xmath6 can kilic@xmath7 michael park@xmath6 0.1 in sunil somalwar@xmath6 and scott thomas@xmath6 0.25 in @xmath6_department of physics + rutgers university + piscataway , nj 08854 _ 0.15 in @xmath8 _ theory group , department of physics and texas cosmology center + the university of texas at austin + austin , tx 78712 _ 0.75 in
| 274
|
1211.4984
|
molecular hydrogen is the most abundant molecule in the universe . a large fraction of h@xmath0 forms by association of hydrogen atoms adsorbed on polycyclic aromatic hydrocarbons ( pahs ) , where formation rates depend crucially on the h sticking probability . we have experimentally studied pah hydrogenation by exposing coronene cations , confined in a radiofrequency ion trap , to gas phase atomic hydrogen . a systematic increase of the number of h atoms adsorbed on the coronene with the time of exposure is observed . odd coronene hydrogenation states dominate the mass spectrum up to 11 h atoms attached . this indicates the presence of a barrier preventing h attachment to these molecular systems . for the second and fourth hydrogenation , barrier heights of 72 @xmath1 6 mev and 40 @xmath1 10 mev , respectively are found which is in good agreement with theoretical predictions for the hydrogenation of neutral pahs . our experiments however prove that the barrier does not vanish for higher hydrogenation states . these results imply that pah cations , as their neutral counterparts , exist in highly hydrogenated forms in the interstellar medium . due to this catalytic activity , pah cations and neutrals seem to contribute similarly to the formation of h@xmath0 .
| 212
|
1606.07723
|
a clock steps a computer through a cycle of phases . for the propagation of logical symbols from one computer to another , each computer must mesh its phases with arrivals of symbols from other computers . even the best atomic clocks drift unforeseeably in frequency and phase ; feedback steers them toward aiming points that depend on a chosen wave function and on hypotheses about signal propagation . a wave function , always under - determined by evidence , requires a guess . guessed wave functions are coded into computers that steer atomic clocks in frequency and position clocks that step computers through their phases of computations , as well as clocks , some on space vehicles , that supply evidence of the propagation of signals . recognizing the dependence of the phasing of symbol arrivals on guesses about signal propagation elevates ` logical synchronization . ' from its practice in computer engineering to a dicipline essential to physics . within this discipline we begin to explore questions invisible under any concept of time that fails to acknowledge the unforeseeable . in particular , variation of spacetime curvature is shown to limit the bit rate of logical communication .
| 200
|
1610.08879
|
cracks are created by massive breakage of molecular or atomic bonds . the latter , in its turn , leads to the highly localized loss of material , which is the reason why even closed cracks are visible by a naked eye . thus , fracture can be interpreted as the local material sink . mass conservation is violated locally in the area of material failure . we consider a theoretical formulation of the coupled mass and momenta balance equations for a description of fracture . our focus is on brittle fracture and we propose a finite strain hyperelastic thermodynamic framework for the coupled mass - flow - elastic boundary value problem . the attractiveness of the proposed framework as compared to the traditional continuum damage theories is that no internal parameters ( like damage variables , phase fields etc . ) are used while the regularization of the failure localization is provided by the physically sound law of mass balance .
| 162
|
0902.4334
|
we consider an anderson impurity model in which the locally correlated orbital is coupled to a host with a gapped density of states . single - particle dynamics are studied , within a perturbative framework that includes both explicit second - order perturbation theory and self - consistent perturbation theory to all orders in the interaction . away from particle - hole symmetry the system is shown to be a generalized fermi liquid ( gfl ) in the sense of being perturbatively connectable to the non - interacting limit ; and the exact friedel sum rule for the gfl phase is obtained . we show by contrast that the particle - hole symmetric point of the model is not perturbatively connected to the non - interacting limit , and as such is a non - fermi liquid for all non - zero gaps . our conclusions are in agreement with nrg studies of the problem .
| 156
|
1403.4634
|
we investigate the signatures at the large hadron collider of a minimal model where the dark matter particle is a majorana fermion that couples to the standard model via one or several coloured mediators . we emphasize the importance of the production channel of coloured scalars through the exchange of a dark matter particle in the t - channel , and perform a dedicated analysis of searches for jets and missing energy for this model . we find that the collider constraints are highly competitive compared to direct detection , and can even be considerably stronger over a wide range of parameters . we also discuss the complementarity with searches for spectral features at gamma - ray telescopes and comment on the possibility of several coloured mediators , which is further constrained by flavour observables .
| 136
|
0710.0928
|
let @xmath0 be a vector space over a field or skew field @xmath1 , and let @xmath2 be its subspace . we study the canonical form problem for bilinear or sesquilinear forms @xmath3 and linear mappings @xmath4 @xmath5 @xmath6 @xmath7 we solve it over @xmath8 and reduce it over all @xmath1 to the canonical form problem for ordinary linear mappings @xmath9 and bilinear or sesquilinear forms @xmath10 . moreover , we give an algorithm that realizes this reduction . the algorithm uses only unitary transformations if @xmath11 , which improves its numerical stability . for linear mapping this algorithm can be derived from the algorithm by l. a. nazarova , a. v. roiter , v. v. sergeichuk , and v. m. bondarenko [ _ j . soviet math . _ 3 ( no . 5 ) ( 1975 ) 636654 ] . _ ams classification : _ 15a21 , 15a63 _ keywords : _ canonical matrices ; classification ; linear operators ; bilinear and sesquilinear forms [ theorem]lemma [ theorem]definition
| 170
|
1502.03689
|
the large and rapidly varying electric and magnetic fields induced by the spectator systems moving at ultrarelativistic velocities induce a charge splitting of directed flow , @xmath0 , of positive and negative pions in the final state of the heavy ion collision . the same effect results in a very sizeable distortion of charged pion spectra as well as ratios of charged pions ( @xmath1 ) emitted at high values of rapidity . both phenomena are sensitive to the actual distance between the pion emission site and the spectator system . this distance @xmath2 appears to decrease with increasing rapidity of the pion , and comes below @xmath31 fm for pions emitted close to beam rapidity . in this paper we discuss how these findings can shed new light on the space - time evolution of pion production as a function of rapidity , and on the longitudinal evolution of the system created in heavy ion collisions .
| 158
|
1107.1133
|
the decay of the @xmath0 boson into supersymmetric particles is studied . we investigate how these supersymmetric modes affect the current limits from the tevatron and project the expected sensitivities at the lhc . employing three representative supersymmetric @xmath0 models , namely , @xmath1 , @xmath2 , and the sequential model , we show that the current limits of the @xmath0 mass from the tevatron could be reduced substantially due to the weakening of the branching ratio into leptonic pairs . the mass reach for the @xmath1 @xmath0 bosons is about @xmath3 tev at the lhc-7 ( 1 fb@xmath4 ) , about @xmath5 tev at the lhc-10 ( 10 fb@xmath4 ) , and about @xmath6 tev at the lhc-14 ( 100 fb@xmath4 ) . a similar mass reach for the @xmath2 @xmath0 is also obtained . we also examine the potential of identifying various supersymmetric decay modes of the @xmath0 boson because it may play a crucial role in the detailed dynamics of supersymmetry breaking .
| 166
|
1305.5620
|
we describe numerical simulations , using the particle - in - cell ( pic ) and hybrid - pic code lsp [ t. p. hughes et al . , phys . rev . st accel . beams * 2 * , 110401 ( 1999 ) ] , of the head - on merging of two laboratory supersonic plasma jets . the goals of these experiments are to form and study astrophysically relevant collisionless shocks in the laboratory . using the plasma jet initial conditions ( density @xmath0@xmath1 @xmath2 , temperature @xmath3 few ev , and propagation speed @xmath4100 km / s ) , large - scale simulations of jet propagation demonstrate that interactions between the two jets are essentially collisionless at the merge region . in highly resolved one- and two - dimensional simulations , we show that collisionless shocks are generated by the merging jets when immersed in applied magnetic fields ( @xmath51 kg ) . at expected plasma jet speeds of up to 100 km / s , our simulations do not give rise to unmagnetized collisionless shocks , which require much higher velocities . the orientation of the magnetic field and the axial and transverse density gradients of the jets have a strong effect on the nature of the interaction . we compare some of our simulation results with those of previously published pic simulation studies of collisionless shock formation .
| 234
|
hep-th0306231
|
a fuzzy circle and a fuzzy 3-sphere are constructed as subspaces of fuzzy complex projective spaces , of complex dimension one and three , by modifying the laplacians on the latter so as to give unwanted states large eigenvalues . this leaves only states corresponding to fuzzy spheres in the low energy spectrum ( this allows the commutative algebra of functions on the continuous sphere to be approximated to any required degree of accuracy ) . the construction of a fuzzy circle opens the way to fuzzy tori of any dimension , thus circumventing the problem of power law corrections in possible numerical simulations on these spaces .
| 108
|
0802.2945
|
we measure the projected rotational velocities of the late b - type hypervelocity stars hvs7 and hvs8 from high resolution spectroscopy to be 60 @xmath0 17 km s@xmath1 and 260 @xmath0 70 km s@xmath1 . the slow rotation of hvs7 is in principle consistent with having originated in a binary system , assuming a high inclination angle of the stellar rotation axis . however , the fast rotation of hvs8 is more typical of single b - type stars . hvs8 could have therefore been ejected by a mechanism other than that proposed by hills . we also estimate the effective temperatures and surface gravities for hvs7 and hvs8 and obtain an additional measurement of their radial velocities . we find evidence in support of a blue horizontal branch nature for hvs7 , and a main sequence nature for hvs8 .
| 141
|
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