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arxiv_dataset-1100902.3784 | Irreducibility in RNA structures
q-bio.BM math.CO q-bio.QM
In this paper we study irreducibility in RNA structures. By RNA structure we
mean RNA secondary as well as RNA pseudoknot structures. In our analysis we
shall contrast random and minimum free energy (mfe) configurations. We compute
various distributions: of the numbers of irreducible substructures, their
locations and sizes, parameterized in terms of the maximal number of mutually
crossing arcs, $k-1$, and the minimal size of stacks $\sigma$. In particular,
we analyze the size of the largest irreducible substructure for random and mfe
structures, which is the key factor for the folding time of mfe configurations.
| arxiv topic:q-bio.BM math.CO q-bio.QM |
arxiv_dataset-1101902.3884 | On the Degree Growth in Some Polynomial Dynamical Systems and Nonlinear
Pseudorandom Number Generators
math.NT math.DS
In this paper we study a class of dynamical systems generated by iterations
of multivariate polynomials and estimate the degreegrowth of these iterations.
We use these estimates to bound exponential sums along the orbits of these
dynamical systems and show that they admit much stronger estimates than in the
general case and thus can be of use for pseudorandom number generation.
| arxiv topic:math.NT math.DS |
arxiv_dataset-1102902.3984 | Photoionized mixing layer models of the diffuse ionized gas
astro-ph.GA
It is generally believed that O stars, confined near the galactic midplane,
are somehow able to photoionize a significant fraction of what is termed the
"diffuse ionized gas" (DIG) of spiral galaxies, which can extend up to 1-2 kpc
above the galactic midplane. The heating of the DIG remains poorly understood,
however, as simple photoionization models do not reproduce the observed line
ratio correlations well or the DIG temperature. We present turbulent mixing
layer models in which warm photoionized condensations are immersed in a hot
supersonic wind. Turbulent dissipation and mixing generate an intermediate
region where the gas is accelerated, heated and mixed. The emission spectrum of
such layers are compared with observations of Rand (ApJ 462, 712) of the DIG in
the edge-on spiral NGC2363. We generate two sequence of models that fit the
line ratio correlations between [SII]/H-alpha, [OI]/H-alpha, [NII]/[SII] and
[OIII]/H-beta reasonably well. In one sequence of models the hot wind velocity
increases while in the other the ionization parameter and layer opacity
increases. Despite the success of the mixing layer models, the overall
efficiency in reprocessing the stellar UV is much too low, much less than 1%,
which compels us to reject the TML model in its present form.
| arxiv topic:astro-ph.GA |
arxiv_dataset-1103902.4084 | Counting domino trains
math.CO math.HO
In this paper we present a way to count the number of trains that we can
construct with a given set of domino pieces. As an application we obtain a new
method to compute the total number of eulerian paths in an undirected graph as
well as their starting and ending vertices.
| arxiv topic:math.CO math.HO |
arxiv_dataset-1104902.4184 | Selective excitations of trasverse vibrational modes of a carbon
nanotube through a "shuttle-like" electromechanical instability
cond-mat.mes-hall
We study the dynamics of transverse oscillations of a suspended carbon
nanotube into which current is injected from the tip of a scanning tunneling
microscope (STM). In this case the correlations between the displacement of the
nanotube and its charge state, determined by the position-dependent electron
tunneling rate, can lead to a "shuttle-like" instability for the transverse
vibrational modes. We find that selective excitation of a specific mode can be
achieved by an accurate positioning of the STM tip. This result suggests a
feasible way to control the dynamics of this nano-electromechanical system
(NEMS) based on the "shuttle instability".
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-1105902.4284 | Fixed Points of the q-Bracket on the p-Adic Unit Disk
math.NT
We study the fixed points of the q-bracket on the complex unit disk, and
prove the following. The set of (nontrivial) pairs (x,q) such that [x]_q=x form
a manifold whose standard projections both have degree p-2. There is an
analytic function Q(X) taking x to q for which [x]_q=x, which is a (bijective)
contraction unless the multiplicity of the residue of x in the fiber over q is
two. The restriction of the theory to Z_p is trivial unless p=3.
| arxiv topic:math.NT |
arxiv_dataset-1106902.4384 | A proposed testbed for detector tomography
quant-ph
Measurement is the only part of a general quantum system that has yet to be
characterized experimentally in a complete manner. Detector tomography provides
a procedure for doing just this; an arbitrary measurement device can be fully
characterized, and thus calibrated, in a systematic way without access to its
components or its design. The result is a reconstructed POVM containing the
measurement operators associated with each measurement outcome. We consider two
detectors, a single-photon detector and a photon-number counter, and propose an
easily realized experimental apparatus to perform detector tomography on them.
We also present a method of visualizing the resulting measurement operators.
| arxiv topic:quant-ph |
arxiv_dataset-1107902.4484 | Resistive relaxation of a magnetically confined mountain on an accreting
neutron star
astro-ph.HE
Three-dimensional numerical magnetohydrodynamic (MHD) simulations are
performed to investigate how a magnetically confined mountain on an accreting
neutron star relaxes resistively. No evidence is found for non-ideal MHD
instabilities on a short time-scale, such as the resistive ballooning mode or
the tearing mode. Instead, the mountain relaxes gradually as matter is
transported across magnetic surfaces on the diffusion time-scale, which
evaluates to $\tau_\mathrm{I} \sim 10^5 - 10^8$ yr (depending on the
conductivity of the neutron star crust) for an accreted mass of $M_a = 1.2
\times 10^{-4} M_\odot$. The magnetic dipole moment simultaneously reemerges as
the screening currents dissipate over $\tau_\mathrm{I}$. For nonaxisymmetric
mountains, ohmic dissipation tends to restore axisymmetry by magnetic
reconnection at a filamentary neutral sheet in the equatorial plane. Ideal-MHD
oscillations on the Alfv\'{e}n time-scale, which can be excited by external
influences, such as variations in the accretion torque, compress the magnetic
field and hence decrease $\tau_\mathrm{I}$ by \change{one order of magnitude}
relative to its standard value (as computed for the static configuration). The
implications of long-lived mountains for gravitational wave emission from
low-mass X-ray binaries are briefly explored.
| arxiv topic:astro-ph.HE |
arxiv_dataset-1108902.4584 | Diagram method in research on coadjoint orbits
math.RT math.SG
We correspond to any factor algebra of the unitriangular Lie algebra with
respect to a regular ideal some permutation. In terms of this permutation one
can construct a diagram, that allows to calculate index and maximal dimension
of coadjoint representation.
| arxiv topic:math.RT math.SG |
arxiv_dataset-1109902.4684 | Quantized Interest Rate at the Money for American Options
q-fin.PR
In this work, we expand the idea of Samuelson[3] and Shepp[2,5,6] for stock
optimization using the Bachelier model [4] as our models for the stock price at
the money (X[stock price]= K[strike price]) for the American call and put
options [1]. At the money (X= K) for American options, the expected payoff of
both the call and put options is zero. Shepp investigated several stochastic
optimization problems using martingale and stopping time theories [2,5,6]. One
of the problems he investigated was how to optimize the stock price using both
the Black-Scholes (multiplicative) and the Bachelier (additive) models [7,6]
for the American option above the strike price K (exercise price) to a stopping
point. In order to explore the non-relativistic quantum effect on the expected
payoff for both the call and put options at the money, we assumed the stock
price to undergo a stochastic process governed by the Bachelier (additive)
model [4]. Further, using Ito calculus and martingale theory, we obtained a
differential equation for the expected payoff for both the call and put options
in terms of delta and gamma. We also obtained the solution to the
non-relativistic Schroedinger equation as the expected payoff for both the call
and put options. Then, we expressed the stochastic process that is the expected
payoff for both the call and put options at the money in terms of the solution
to the Schroedinger equation. We concluded the stochastic process that is the
expected payoff at the money for both options to be an oscillatory function
with quantized interest rates.
| arxiv topic:q-fin.PR |
arxiv_dataset-1110902.4784 | Integrated functionals of normal and fractional processes
math.PR
Consider $Z^f_t(u)=\int_0^{tu}f(N_s) ds$, $t>0$, $u\in[0,1]$, where
$N=(N_t)_{t\in\mathbb{R}}$ is a normal process and $f$ is a measurable
real-valued function satisfying $Ef(N_0)^2<\infty$ and $Ef(N_0)=0$. If the
dependence is sufficiently weak Hariz [J. Multivariate Anal. 80 (2002)
191--216] showed that $Z_t^f/t^{1/2}$ converges in distribution to a multiple
of standard Brownian motion as $t\to\infty$. If the dependence is sufficiently
strong, then $Z_t/(EZ_t(1)^2)^{1/2}$ converges in distribution to a higher
order Hermite process as $t\to\infty$ by a result by Taqqu [Wahrsch. Verw.
Gebiete 50 (1979) 53--83]. When passing from weak to strong dependence, a
unique situation encompassed by neither results is encountered. In this paper,
we investigate this situation in detail and show that the limiting process is
still a Brownian motion, but a nonstandard norming is required. We apply our
result to some functionals of fractional Brownian motion which arise in time
series. For all Hurst indices $H\in(0,1)$, we give their limiting
distributions. In this context, we show that the known results are only
applicable to $H<3/4$ and $H>3/4$, respectively, whereas our result covers
$H=3/4$.
| arxiv topic:math.PR |
arxiv_dataset-1111902.4884 | Prospects for Quantum Computing
physics.gen-ph
This note reviews prospects for quantum computing. It argues that gates need
to be tested for a wide range of probability amplitudes.
| arxiv topic:physics.gen-ph |
arxiv_dataset-1112903.0081 | Phase transition in Schwarzschild-de Sitter spacetime
gr-qc math-ph math.MP
Using a static massive spherically symmetric scalar field coupled to gravity
in the Schwarzschild-de Sitter (SdS) background, first we consider some
asymptotic solutions near horizon and their local equations of state(E.O.S) on
them. We show that near cosmological and event horizons our scalar field
behaves as a dust. At the next step near two pure de-Sitter or Schwarzschild
horizons we obtain a coupling dependent pressure to energy density ratio. In
the case of a minimally couplling this ratio is -1 which springs to the mind
thermodynamical behavior of dark energy. If having a negative pressure behavior
near these horizons we concluded that the coupling constant must be $\xi<{1/4}$
>. Therefore we derive a new constraint on the value of our coupling $\xi$ .
These two different behaviors of unique matter in the distinct regions of
spacetime at present era can be interpreted as a phase transition from dark
matter to dark energy in the cosmic scales and construct a unified scenario.
| arxiv topic:gr-qc math-ph math.MP |
arxiv_dataset-1113903.0181 | MARVELS: Revealing the Formation and Dynamical Evolution of Giant Planet
Systems
astro-ph.EP
MARVELS, the Multi-Object APO Radial Velocity Exoplanet Large-area Survey, is
a 6-year program to characterize the distribution of gas giant planets with
orbital periods ranging from several hours to two years. MARVELS will use
multi-fiber interferometric spectrographs on the wide-field, 2.5-meter Sloan
Foundation telescope at Apache Point Observatory to monitor ~11,000 stars in
the magnitude range V=8-12, visiting each star ~30 times over an 18-month
interval, with velocity precision of 14, 18, and 35 m/s at V=8, 10, and 12.
MARVELS will survey far more stars with a wider range of spectral types and
metallicities than previous radial velocity searches, yielding a statistically
well defined sample of ~150 giant planets drawn from a host sample with well
understood selection biases. With a unique combination of large numbers and
well characterized sensitivity, MARVELS will provide a critical data set for
testing theories of the formation and dynamical evolution of giant planet
systems. The MARVELS detections will also be an ideal sample for follow-up
observations to identify multiple planet systems and understand the influence
of giant planet migration on the formation and survival of less massive
planets. MARVELS is one of four surveys that comprise SDSS-III (the Sloan
Digital Sky Survey III), a 6-year program that will use highly multiplexed
spectrographs on the Sloan Foundation Telescope to investigate cosmological
parameters, the history and structure of the Milky Way galaxy, and the
population of giant planet systems.
| arxiv topic:astro-ph.EP |
arxiv_dataset-1114903.0281 | One-loop Self-energies in the Electroweak Model with Nonlinearly
Realized Gauge Group
hep-th hep-ph
We evaluate at one loop the self-energies in generic D dimensions for the W,Z
mesons in the Electroweak model where the gauge group is nonlinearly realized.
In this model the Higgs boson parameters are absent, while a second mass
parameter appears together with a scale for the radiative corrections. We
estimate these parameters in a simplified fit on leptons and gauge bosons data.
We check physical unitarity and the absence of infrared divergences. Landau
gauge is used.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-1115903.0381 | Profile of bubbling solutions to a Liouville system
math.AP math.CA
In several fields of Physics, Chemistry and Ecology, some models are
described by Liouville systems. In this article we first prove a uniqueness
result for a Liouville system in $\mathbb R^2$. Then we establish an uniform
estimate for bubbling solutions of a locally defined Liouville system near an
isolated blowup point. The uniqueness result, as well as the local uniform
estimates are crucial ingredients for obtaining a priori estimate, degree
counting formulas and existence results for Liouville systems defined on
Riemann surfaces.
| arxiv topic:math.AP math.CA |
arxiv_dataset-1116903.0481 | A pseudo empirical likelihood approach for stratified samples with
nonresponse
stat.ME
Nonresponse is common in surveys. When the response probability of a survey
variable $Y$ depends on $Y$ through an observed auxiliary categorical variable
$Z$ (i.e., the response probability of $Y$ is conditionally independent of $Y$
given $Z$), a simple method often used in practice is to use $Z$ categories as
imputation cells and construct estimators by imputing nonrespondents or
reweighting respondents within each imputation cell. This simple method,
however, is inefficient when some $Z$ categories have small sizes and ad hoc
methods are often applied to collapse small imputation cells. Assuming a
parametric model on the conditional probability of $Z$ given $Y$ and a
nonparametric model on the distribution of $Y$, we develop a pseudo empirical
likelihood method to provide more efficient survey estimators. Our method
avoids any ad hoc collapsing small $Z$ categories, since reweighting or
imputation is done across $Z$ categories. Asymptotic distributions for
estimators of population means based on the pseudo empirical likelihood method
are derived. For variance estimation, we consider a bootstrap procedure and its
consistency is established. Some simulation results are provided to assess the
finite sample performance of the proposed estimators.
| arxiv topic:stat.ME |
arxiv_dataset-1117903.0581 | On the existence of functionals for the mean values of observables
cond-mat.stat-mech
The aim of this work is to study the existence of mean values of observables
for infinite-particle systems. Using solutions of the initial value problems to
the BBGKY hierarchy and to its dual, we prove the local, in time, existence of
the mean value functionals in the cases where either observables or states vary
in time. We also discuss problems on the existence of such functionals for
several different classes of observables and for an arbitrary time interval.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-1118903.0681 | High resolution angle resolved photoemission studies on quasi-particle
dynamics in graphite
cond-mat.mtrl-sci
We obtained the spectral function of the graphite H point using high
resolution angle resolved photoelectron spectroscopy (ARPES). The extracted
width of the spectral function (inverse of the photo-hole lifetime) near the H
point is approximately proportional to the energy as expected from the linearly
increasing density of states (DOS) near the Fermi energy. This is well
accounted by our electron-phonon coupling theory considering the peculiar
electronic DOS near the Fermi level. And we also investigated the temperature
dependence of the peak widths both experimentally and theoretically. The upper
bound for the electron-phonon coupling parameter is ~0.23, nearly the same
value as previously reported at the K point. Our analysis of temperature
dependent ARPES data at K shows that the energy of phonon mode of graphite has
much higher energy scale than 125K which is dominant in electron-phonon
coupling.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-1119903.0781 | On the 1D Modeling of Fluid Flowing through a Junction
math.AP math-ph math.MP
Consider a fluid flowing through a junction between two pipes with different
sections. Its evolution is described by the 2D or 3D Euler equations, whose
analytical theory is far from complete and whose numerical treatment may be
rather costly. This note compares different 1D approaches to this phenomenon.
| arxiv topic:math.AP math-ph math.MP |
arxiv_dataset-1120903.0881 | Accretion of phantom scalar field into a black hole
gr-qc astro-ph.CO hep-th
Using numerical methods we present the first full nonlinear study of phantom
scalar field accreted into a black hole. We study different initial
configurations and find that the accretion of the field into the black hole can
reduce its area down to 50 percent within time scales of the order of few
masses of the initial horizon. The analysis includes the cases where the total
energy of the space-time is positive or negative. The confirmation of this
effect in full nonlinear general relativity implies that the accretion of
exotic matter could be considered an evaporation process. We speculate that if
this sort of exotic matter has some cosmological significance, this black hole
area reduction process might have played a crucial role in black hole formation
and population.
| arxiv topic:gr-qc astro-ph.CO hep-th |
arxiv_dataset-1121903.0981 | Three tupes of self-similar blow-up for the fourth-order p-Laplacian
equaiton with source: variational and branching approaches
math.AP
The fourth-order quasilinear reaction-diffusion equation with a p-Laplacian
operator is shown to admit three types of blow-up. Self-similar patterns are
first constructed for the regional blow-up case, where the rescaled problem
admits a variational setting. Next, these were extended via a branching
approach to non-variational problems.
| arxiv topic:math.AP |
arxiv_dataset-1122903.1081 | High-energy gluon bremsstrahlung in a finite medium: harmonic oscillator
versus single scattering approximation
nucl-th hep-ph
A particle produced in a hard collision can lose energy through
bremsstrahlung. It has long been of interest to calculate the effect on
bremsstrahlung if the particle is produced inside a finite-size QCD medium such
as a quark-gluon plasma. For the case of very high-energy particles traveling
through the background of a weakly-coupled quark-gluon plasma, it is known how
to reduce this problem to an equivalent problem in non-relativistic
two-dimensional quantum mechanics. Analytic solutions, however, have always
resorted to further approximations. One is a harmonic oscillator approximation
to the corresponding quantum mechanics problem, which is appropriate for
sufficiently thick media. Another is to formally treat the particle as having
only a single significant scattering from the plasma (known as the N=1 term of
the opacity expansion), which is appropriate for sufficiently thin media. In a
broad range of intermediate cases, these two very different approximations give
surprisingly similar but slightly differing results if one works to leading
logarithmic order in the particle energy, and there has been confusion about
the range of validity of each approximation. In this paper, I sort out in
detail the parametric range of validity of these two approximations at leading
logarithmic order. For simplicity, I study the problem for small alpha_s and
large logarithms but alpha_s log << 1.
| arxiv topic:nucl-th hep-ph |
arxiv_dataset-1123903.1181 | On the mechanism of high-temperature superconductivity in the iron based
pnictides
cond-mat.supr-con
The recent discovery of superconductivity at moderately high temperature (26
K to 55 K) in doped iron-based pnictides (LnO_{1-x}F_xFeAs, where Ln = La, Ce,
Sm, Pr, Nd, etc.), having layered-structure-like cuprates, has triggered
renewed challenge towards understanding the pairing mechanism.
After reviewing the current findings on these systems, a theoretical model of
a combined mechanism is suggested in which the phonon-mediated and
distortion-field-mediated pairing processes give the right order of
superconducting critical temperature T_c. The distortion-field modes arise from
Jahn-Teller or pseudo Jahn-Teller effects due to degenerate or near-degenerate
iron 3d_{xz} and 3d_{yz} orbitals.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-1124903.1281 | A chiral Borel-Weil-Bott theorem
math.AG hep-th math.RT
We compute the cohomology of modules over the algebra of twisted chiral
differential operators over the flag manifold. This is applied to (1) finding
the character of $G$-integrable irreducible highest weight modules over the
affine Lie algebra at the critical level, and (2) computing a certain elliptic
genus of the flag manifold. The main tool is a result that interprets the
Drinfeld-Sokolov reduction as a derived functor.
| arxiv topic:math.AG hep-th math.RT |
arxiv_dataset-1125903.1381 | Combinatorial Hopf algebras and Towers of Algebras - Dimension,
Quantization, and Functoriality
math.CO math.RT
Bergeron and Li have introduced a set of axioms which guarantee that the
Grothendieck groups of a tower of algebras $\bigoplus_{n\ge0}A_n$ can be
endowed with the structure of graded dual Hopf algebras. Hivert and Nzeutzhap,
and independently Lam and Shimozono constructed dual graded graphs from
primitive elements in Hopf algebras. In this paper we apply the composition of
these constructions to towers of algebras. We show that if a tower
$\bigoplus_{n\ge0}A_n$ gives rise to graded dual Hopf algebras then we must
have $\dim(A_n)=r^nn!$ where $r = \dim(A_1)$. In the case $r=1$ we give a
conjectural classification. We then investigate a quantum version of the main
theorem. We conclude with some open problems and a categorification of the
construction. This paper is a full version of the summary arXiv: 0710.3744.
| arxiv topic:math.CO math.RT |
arxiv_dataset-1126903.1481 | M-flation: Inflation From Matrix Valued Scalar Fields
hep-th astro-ph.CO hep-ph
We propose an inflationary scenario, M-flation, in which inflation is driven
by three $N\times N$ hermitian matrices $\Phi_i, i=1,2,3$. The inflation
potential of our model, which is strongly motivated from string theory, is
constructed from $\Phi_{i}$ and their commutators. We show that one can
consistently restrict the classical dynamics to a sector in which the $\Phi_i$
are proportional to the $N\times N$ irreducible representations of SU(2). In
this sector our model effectively behaves as an N-flation model with $3 N^2$
number of fields and the effective inflaton field has a super-Planckian field
value. Furthermore, the fine-tunings associated with unnaturally small
couplings in the chaotic type inflationary scenarios are removed. Due to the
matrix nature of the inflaton fields there are $3N^2-1$ extra scalar fields in
the dynamics. These have the observational effects such as production of
iso-curvature perturbations on cosmic microwave background. Moreover, the
existence of these extra scalars provides us with a natural preheating
mechanism and exit from inflation. As the effective inflaton field can traverse
super-Planckian distances in the field space, the model is capable of producing
a considerable amount of gravity waves that can be probed by future CMB
polarization experiments such as PLANCK, QUIET and CMBPOL.
| arxiv topic:hep-th astro-ph.CO hep-ph |
arxiv_dataset-1127903.1581 | Mangetic phase transition for three-dimensional Heisenberg weak random
anisotropy model: Monte Carlo study
cond-mat.stat-mech
Magnetic phase transition (MPT) to magnetic quasi-long-range order (QLRO)
phase in a three-dimensional Heisenberg weak (D/J=4) random anisotropy (RA)
model is investigated by Monte Carlo simulation. The isotropic and cubic
distributions of RA axes are considered for simple-cubic-lattice systems.
Finite-size scaling analysis shows that the critical couplings for the former
and latter are K_c= 0.70435(2) and K_c=0.70998(4), respectively. While the
critical exponent 1/\nu =1.40824(0) is the same for both cases. A second-order
MPT to the QLRO phase is therefore evidenced to be possible in favor with the
existence of the QLRO predicted by recent functional renormalization group
theories.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-1128903.1681 | First model-independent determination of the relative strong phase
between D0 and D0B --> K0Spi+pi- and its impact on the CKM Angle gamma/phi3
measurement
hep-ex
We exploit the quantum coherence between pair-produced D0 and D0B in
psi(3770) decays to make a first determination of the relative strong phase
differences between D0--> K0Spi+pi- and D0B--> K0Spi+pi-, which are of great
importance in determining the CKM angle gamma/phi3 in B- --> D0 (D0B) K-
decays. Using 818 1/pb of e+e- collision data collected with the CLEO-c
detector at Ecm = 3.77 GeV, we employ a binned Dalitz-plot analysis of K0S
pi+pi- and K0Lpi+pi- decays recoiling against flavor-tagged, CP-tagged and
K0Spi+pi- tagged events to determine these strong phase differences.
| arxiv topic:hep-ex |
arxiv_dataset-1129903.1781 | The role of the background in the extraction of resonance contributions
from meson-baryon scattering
nucl-th
The separation of background and resonance contributions in pion-nucleon
scattering is an often discussed issue. We investigate to what extent the
background can be separated from the pole contribution. For illustration we use
results from an analytic model for the meson-baryon interaction derived from
meson exchange. We focus on the two distinct cases of an elastic and a highly
inelastic resonance, namely the Delta(1232) and the Delta*(1700). Our results
are also relevant for studies of dynamically generated resonances and attempts
to extract bare quantities from hadronic models to be compared to quark model
results.
| arxiv topic:nucl-th |
arxiv_dataset-1130903.1881 | C*-Algebraic Characterization of Bounded Orbit Injection Equivalence for
Minimal Free Cantor Systems
math.DS math.OA
Bounded orbit injection equivalence is an equivalence relation defined on
minimal free Cantor systems which is a candidate to generalize flip Kakutani
equivalence to actions of the Abelian free groups on more than one generator.
This paper characterizes bounded orbit injection equivalence in terms of a mild
strengthening of Rieffel-Morita equivalence of the associated
C*-crossed-product algebras. Moreover, we construct an ordered group which is
an invariant for bounded orbit injection equivalence, and does not agrees with
the K\_0 group of the associated C*-crossed-product in general. This new
invariant allows us to find sufficient conditions to strengthen bounded orbit
injection equivalence to orbit equivalence and strong orbit equivalence.
| arxiv topic:math.DS math.OA |
arxiv_dataset-1131903.1981 | Probing the strong electroweak symmetry breaking in a model with a
vector resonance
hep-ph
We systematically study the possibility to probe the physics behind the
electroweak symmetry breaking at the LHC assuming new strong interactions being
responsible for the effect. The new physics is described by the Higgs-less
effective Lagrangian with a vector resonance in the particle spectrum, in
addition to the Standard Model fields. We analyze signals of the resonance in
the mixing-induced LHC processes pp-> abX,
ab=t\bar{t},b\bar{b},t\bar{b},W^+Z,W^+W^-. At this level of our calculations we
do not consider further decays of the quarks and of the gauge bosons.
| arxiv topic:hep-ph |
arxiv_dataset-1132903.2081 | Arbitrary distribution and nonlinear modal interaction in coupled
nanomechanical resonators
math-ph cond-mat.mes-hall math.MP
We propose a general one-dimensional {\em continuous} formulation to analyze
the vibrational modes of antenna-like nanomechanical resonators consisting of
two symmetric arrays of cantilevers affixed to a central nano-beam. The
cantilever arrays can have arbitrary density and length profile along the beam.
We obtain the secular equation that allows for the determination of their
frequency spectrum and illustrate the results on the particular examples of
structures with constant or alternating cantilever length profiles. We show
that our analytical results capture the vibration spectrum of such resonators
and elucidate key relationships that could prove advantageous for experimental
device performance. Furthermore, using a perturbative approach to treat the
nonlinear and dissipative dynamics of driven structures, we analyze the
anharmonic coupling between two specific widely spaced modes of the
coupled-element device, with direct application to experiments.
| arxiv topic:math-ph cond-mat.mes-hall math.MP |
arxiv_dataset-1133903.2181 | Line Graphs, Link Partitions and Overlapping Communities
physics.soc-ph physics.data-an
In this paper, we use a partition of the links of a network in order to
uncover its community structure. This approach allows for communities to
overlap at nodes, so that nodes may be in more than one community. We do this
by making a node partition of the line graph of the original network. In this
way we show that any algorithm which produces a partition of nodes can be used
to produce a partition of links. We discuss the role of the degree
heterogeneity and propose a weighted version of the line graph in order to
account for this.
| arxiv topic:physics.soc-ph physics.data-an |
arxiv_dataset-1134903.2281 | Opening Gaps in the Spectrum of Strictly Ergodic Schr\"odinger Operators
math.DS math-ph math.MP math.SP
We consider Schr\"odinger operators with dynamically defined potentials
arising from continuous sampling along orbits of strictly ergodic
transformations. The Gap Labeling Theorem states that the possible gaps in the
spectrum can be canonically labelled by an at most countable set defined purely
in terms of the dynamics. Which labels actually appear depends on the choice of
the sampling function; the missing labels are said to correspond to collapsed
gaps. Here we show that for any collapsed gap, the sampling function may be
continuously deformed so that the gap immediately opens. As a corollary, we
conclude that for generic sampling functions, all gaps are open. The proof is
based on the analysis of continuous $SL(2,R)$ cocycles, for which we obtain
dynamical results of independent interest.
| arxiv topic:math.DS math-ph math.MP math.SP |
arxiv_dataset-1135903.2381 | Radiative transfer in circumstellar disks - I. 1D models for GQ Lupi
astro-ph.SR astro-ph.IM
We present a new code for the calculation of the 1D structure and synthetic
spectra of accretion disks. The code is an extension of the general purpose
stellar atmosphere code PHOENIX and is therefore capable of including extensive
lists of atomic and molecular lines as well as dust in the calculations. We
assume that the average viscosity can be represented by a critical Reynolds
number in a geometrically thin disk and solve the structure and radiative
transfer equations for a number of disk rings in the vertical direction. The
combination of these rings provides the total disk structure and spectrum.
Since the warm inner regions of protoplanetary disks show a rich molecular
spectrum, they are well suited for a spectral analysis with our models. In this
paper we test our code by comparing our models with high-resolution VLT CRIRES
spectra of the T Tauri star GQ Lup.
| arxiv topic:astro-ph.SR astro-ph.IM |
arxiv_dataset-1136903.2481 | No entropy enigmas for N=4 dyons
hep-th
We explain why multi-centered black hole configurations where at least one of
the centers is a large black hole do not contribute to the indexed degeneracies
in theories with N=4 supersymmetry. This is a consequence of the fact that such
configurations, although supersymmetric, belong to long supermultiplets. As a
result, there is no entropy enigma in N=4 theories, unlike in N=2 theories.
| arxiv topic:hep-th |
arxiv_dataset-1137903.2581 | Conical singularities regularized in warped six-dimensional flux
compactification and their induced brane cosmology
hep-th
We discuss the regularization of codimension-2 singularities in warped
six-dimensional Einstein-Maxwell axisymmetric models by replacing them by
codimension-1 branes of a ring form, situated around the axis of symmetry.
Further we consider the case of one capped regularized conical brane of
codimension one and study the cosmological evolution which is induced on it as
it moves in between the known {\it static} bulk and cap solutions. We present
the resulting brane Friedmann equation which gives a dominant five-dimensional
$\rho^2$ energy density term at high energies and a term linear to the energy
density at low energies with, however, negative coefficient in the small
four-brane radius limit (i.e. with negative effective Newton's constant)
| arxiv topic:hep-th |
arxiv_dataset-1138903.2681 | The Jahn-Teller instability in dissipative quantum electromechanical
systems
cond-mat.mes-hall cond-mat.supr-con quant-ph
We consider the steady states of a harmonic oscillator coupled so strongly to
a two-level system (a qubit) that the rotating wave approximation cannot be
made. The Hamiltonian version of this model is known as the $E\otimes\beta$
Jahn-Teller model. The semiclassical version of this system exhibits a fixed
point bifurcation, which in the quantum model leads to a ground state with
substantial entanglement between the oscillator and the qubit. We show that the
dynamical bifurcation survives in a dissipative quantum description of the
system, amidst an even richer bifurcation structure. We propose two
experimental implementations of this model based on superconducting cavities: a
parametrically driven nonlinear nanomechanical resonator coupled capacitively
to a coplanar microwave cavity and a superconducting junction in the central
conductor of a coplanar waveguide.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con quant-ph |
arxiv_dataset-1139903.2781 | Hyperplane sections of abelian surfaces
math.AG
By a theorem of Wahl, the canonically embedded curves which are hyperplane
section of K3 surfaces are distinguished by the non-surjectivity of their Wahl
map. In this paper we address the problem of distinguishing hyperplane sections
of abelian surfaces. The somewhat surprising result is that the Wahl map of
such curves is (tendentially) surjective, but their second Wahl map has corank
at least 2 (in fact a more precise result is proved).
| arxiv topic:math.AG |
arxiv_dataset-1140903.2881 | Spin Fluctuations and the Pseudogap in Organic Superconductors
cond-mat.supr-con cond-mat.str-el
We show that there are strong similarities in the spin lattice relaxation of
non-magnetic organic charge transfer salts, and that these similarities can be
understood in terms of spin fluctuations. Further, we show that, in all of the
kappa-phase organic superconductors for which there is nuclear magnetic
resonance data, the energy scale for the spin fluctuations coincides with the
energy scale for the pseudogap. This suggests that the pseudogap is caused by
short-range spin correlations. In the weakly frustrated metals
k-(BEDT-TTF)_2Cu[N(CN)_2]Br, k-(BEDT-TTF)_2Cu(NCS)_2, and
k-(BEDT-TTF)_2Cu[N(CN)_2]Cl (under pressure) the pseudogap opens at the same
temperature as coherence emerges in the (intralayer) transport. We argue that
this is because the spin correlations are cut off by the loss of intralayer
coherence at high temperatures. We discuss what might happen to these two
energy scales at high pressures, where the electronic correlations are weaker.
In these weakly frustrated materials the data is well described by the chemical
pressure hypothesis (that anion substitution is equivalent to hydrostatic
pressure). However, we find important differences in the metallic state of
k-(BEDT-TTF)_2Cu_2(CN)_3, which is highly frustrated and displays a spin liquid
insulating phase. We also show that the characteristic temperature scale of the
spin fluctuations in (TMTSF)_2ClO_4 is the same as superconducting critical
temperature, which may be evidence that spin fluctuations mediate the
superconductivity in the Bechgaard salts.
| arxiv topic:cond-mat.supr-con cond-mat.str-el |
arxiv_dataset-1141903.2981 | Energy Spectra of the Soft X-ray Diffuse Emission in Fourteen Fields
Observed with Suzaku
astro-ph.GA astro-ph.HE
The soft diffuse X-ray emission of twelve fields observed with Suzaku are
presented together with two additional fields from previous analyses. All have
galactic longitudes 65 deg < l < 295 deg to avoid contributions from the very
bright diffuse source that extends at least 30 deg from the Galactic center.
The surface brightnesses of the Suzaku nine fields for which apparently
uncontaminated ROSAT All Sky Survey (RASS) were available were statistically
consistent with the RASS values, with an upper limit for differences of 17 x
10^{-6} c s^{-1} amin^{-2} in R45}-band. The Ovii and Oviii intensities are
well correlated to each other, and Ovii emission shows an intensity floor at ~2
photons s^{-1} cm^{-2 str^{-1} (LU). The high-latitude Oviii emission shows a
tight correlation with excess of Ovii emission above the floor, with (Oviii
intensity) = 0.5 x [(Ovii intensity) -2 LU], suggesting that temperatures
averaged over different line-of-sight show a narrow distribution around ~0.2
keV. We consider that the offset intensity of Ovii arises from the Heliospheric
solar wind charge exchange and perhaps from the local hot bubble, and that the
excess Ovii (2-7 LU) is emission from more distant parts of the Galaxy. The
total bolometric luminosity of this galactic emission is estimated to be 4 x
10^{39} erg s^{-1}, and its characteristic temperature may be related to the
virial temperature of the Galaxy.
| arxiv topic:astro-ph.GA astro-ph.HE |
arxiv_dataset-1142903.3081 | On normal approximations to $U$-statistics
math.PR
Let ${X_1,...,X_n}$ be i.i.d. random observations. Let
$\mathbb{S}=\mathbb{L}+\mathbb{T}$ be a $U$-statistic of order $k\ge2$ where
$\mathbb{L}$ is a linear statistic having asymptotic normal distribution, and
$\mathbb{T}$ is a stochastically smaller statistic. We show that the rate of
convergence to normality for $\mathbb{S}$ can be simply expressed as the rate
of convergence to normality for the linear part $\mathbb{L}$ plus a correction
term, $(\operatorname {var}\mathbb{T})\ln^2(\operatorname {var}\mathbb{T})$,
under the condition ${\mathbb{E}\mathbb{T}^2<\infty}$. An optimal bound without
this $\log$ factor is obtained under a lower moment assumption ${\mathbb
{E}|\mathbb{T}|^{\alpha}<\infty}$ for ${\alpha<2}$. Some other related results
are also obtained in the paper. Our results extend, refine and yield a number
of related-known results in the literature.
| arxiv topic:math.PR |
arxiv_dataset-1143903.3181 | Semirelativistic Hamiltonians and the auxiliary field method
quant-ph hep-ph
Approximate analytical closed energy formulas for semirelativistic
Hamiltonians of the form $\sigma\sqrt{\bm p^{2}+m^2}+V(r)$ are obtained within
the framework of the auxiliary field method. This method, which is equivalent
to the envelope theory, has been recently proposed as a powerful tool to get
approximate analytical solutions of the Schr\"odinger equation. Various shapes
for the potential $V(r)$ are investigated: power-law, funnel, square root, and
Yukawa. A comparison with the exact results is discussed in detail.
| arxiv topic:quant-ph hep-ph |
arxiv_dataset-1144903.3281 | Cluster characters II: A multiplication formula
math.RT
Let $\mathcal{C}$ be a Hom-finite triangulated 2-Calabi-Yau category with a
cluster tilting object. Under some constructibility assumptions on
$\mathcal{C}$ which are satisfied for instance by cluster categories, by
generalized cluster categories and by stable categories of modules over a
preprojective algebra, we prove a multiplication formula for the cluster
character associated with any cluster tilting object. This formula generalizes
those obtained by Caldero-Keller for representation finite path algebras and by
Xiao-Xu for finite-dimensional path algebras. It is analogous to a formula
obtained by Geiss-Leclerc-Schr\"oer in the context of preprojective algebras.
| arxiv topic:math.RT |
arxiv_dataset-1145903.3381 | Minimal Dark Matter: model and results
hep-ph
We recap the main features of Minimal Dark Matter (MDM) and assess its status
in the light of the recent experimental data. The theory selects an electroweak
5-plet with hypercharge Y=0 as a fully successful DM candidate, automatically
stable against decay and with no free parameters: DM is a fermion with a 9.6
TeV mass. The direct detection cross-section, predicted to be 10^-44 cm2, is
within reach of next-generation experiments. DM is accompanied by a charged
fermion 166 MeV heavier: we discuss how it might manifest. Thanks to an
electroweak Sommerfeld enhancement of more than 2 orders of magnitude, DM
annihilations into W+W- give, in presence of a modest astrophysical boost
factor, a positron flux compatible with the PAMELA excess (but not with the
ATIC hint for a peak: MDM instead predicts a quasi-power-law spectrum), a
anti-proton flux concentrated at energies above 100 GeV, and to photon fluxes
comparable with present limits, depending on the DM density profile.
| arxiv topic:hep-ph |
arxiv_dataset-1146903.3481 | K3 surfaces with non-symplectic automorphisms of prime order
math.AG
In this note we present the classification of non-symplectic automorphisms of
prime order on K3 surfaces, i.e.we describe the topological structure of their
fixed locus and determine the invariant lattice in cohomology. We provide new
results for automorphisms of order 5 and 7 and alternative proofs for higher
orders. Moreover, for any prime p, we identify the irreducible components of
the moduli space of K3 surfaces with a non-symplectic automorphism of order p.
| arxiv topic:math.AG |
arxiv_dataset-1147903.3581 | Lefschetz elements of Artinian Gorenstein algebras and Hessians of
homogeneous polynomials
math.AC
We give a characterization of the Lefschetz elements in Artinian Gorenstein
rings over a field of characteristic zero in terms of the higher Hessians. As
an application, we give new examples of Artinian Gorenstein rings which do not
have the strong Lefschetz property.
| arxiv topic:math.AC |
arxiv_dataset-1148903.3681 | Physical Consequences of Complex Dimensions of Fractals
cond-mat.mes-hall cond-mat.stat-mech hep-th math-ph math.MP quant-ph
It has recently been realized that fractals may be characterized by complex
dimensions, arising from complex poles of the corresponding zeta function, and
we show here that these lead to oscillatory behavior in various physical
quantities. We identify the physical origin of these complex poles as the
exponentially large degeneracy of the iterated eigenvalues of the Laplacian,
and discuss applications in quantum mesoscopic systems such as oscillations in
the fluctuation $\Sigma^2 (E)$ of the number of levels, as a correction to
results obtained in Random Matrix Theory. We present explicit expressions for
these oscillations for families of diamond fractals, also studied as
hierarchical lattices.
| arxiv topic:cond-mat.mes-hall cond-mat.stat-mech hep-th math-ph math.MP quant-ph |
arxiv_dataset-1149903.3781 | Synechococcus as a "singing" bacterium: biology inspired by
micro-engineered acoustic streaming devices
physics.bio-ph
Certain cyanobacteria, such as open ocean strains of Synechococcus, are able
to swim at speeds up to 25 diameters per second, without flagella or visible
changes in shape. The means by which Synechococcus generates thrust for
self-propulsion is unknown. The only mechanism that has not been ruled out
employs tangential waves of surface deformations. In Ehlers et al, the average
swimming velocity for this mechanism was estimated using the methods
inaugurated by Taylor and Lighthill in the 1950's and revisited in differential
geometric language by Shapere and Wilczek in 1989. In this article we propose
an entirely different physical principle self propulsion based on acoustic
streaming (AS). Micro-pumps in silicon chips, based on AS, have been
constructed by engineers since the 1990's, but to the best of our knowledge
acoustic streaming as a means of microorganisms locomotion has not been
proposed before. Our hypothesis is supported by two recent discoveries: (1) In
Samuel, et al, deep-freeze electron microscopy of the motile strain WH8113
revealed a crystalline outer layer (CS) covered with a forest of "spicules"
(Sp) extending from the inner membrane through the CS, projecting 150 nm into
the surrounding fluid. (2) In Pelling et al, atomic force microscopy (AFM) was
used to find that the cell wall of yeast cells periodically oscillates on
nano-scale amplitudes at frequencies of 0.8 to 1.6 kHz, and that the
oscillations are generated metabolically. We propose that the spicules, in
contact with the cell's power systems, could perform high frequency motions
generating acoustic streaming (AS) in the surrounding fluid. We compare two
models for self-propulsion employing acoustic streaming: the quartz wind effect
(QW) and boundary induced streaming generated by surface acoustic waves (SAW).
| arxiv topic:physics.bio-ph |
arxiv_dataset-1150903.3881 | A conformally coupled massive scalar field in the de Sitter expanding
universe with the mass term treated as a perturbation
gr-qc hep-th
We study conformally-coupled massive scalar field theory with the mass term
treated as a perturbation in the expanding half of de Sitter spacetime as a toy
model for comparing various perturbative formalisms. We point out that the
in-out perturbation theory breaks down due to infrared divergences coming from
the infinite future. We then clarify the relation between the free-theory
vacuum and the true vacuum using the Bogolubov transformation and show that the
discrepancy between the free-theory out-vacuum and the true vacuum causes
apparent pair creation of free-theory particles and makes the in-out two-point
function differ from the true two-point function. We also identify the infinite
Bogolubov coefficients as the cause of infrared divergences. We then examine
two alternative approaches: the Euclidean and in-in formalisms. We verify that
there are no infrared divergences in perturbation theory with the mass term
treated as a perturbation in either of these approaches and that the two-point
function of massive scalar field is reproduced correctly by these methods.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-1151903.3981 | On Estimating the Flux of the Brightest Cosmic Ray Source above 57x10^18
eV
astro-ph.HE
The sources of ultra-high energy cosmic rays are not yet known. However, the
discovery of anisotropic cosmic rays above 57x10^18 eV by the Pierre Auger
Observatory suggests that a direct source detection may soon be possible. The
near-future prospects for such a measurement are heavily dependent on the flux
of the brightest source. In this work, we show that the flux of the brightest
source above 57x10^18 eV is expected to comprise 10% or more of the total flux
if two general conditions are true. The conditions are: 1.) the source objects
are associated with galaxies other than the Milky Way and its closest
neighbors, and 2.) the cosmic ray particles are protons or heavy nuclei such as
iron and the Greisen-Zatsepin-Kuz'min effect is occurring. The Pierre Auger
Observatory collects approximately 23 events above 57x10^18 eV per year.
Therefore, it is plausible that, over the course of several years, tens of
cosmic rays from a single source will be detected.
| arxiv topic:astro-ph.HE |
arxiv_dataset-1152903.4081 | Integral representations on non-smooth domains
math.CV
We derive integral representations for $(0,q)$-forms, $q\ge1$, on non-smooth
strictly pseudoconvex domains, the Henkin-Leiterer domains. A $(0,q)$-form, $f$
is written in terms of integral operators acting on $f$, $\mdbar f$, and
$\mdbar^{\ast} f$. The representation is applied to derive $L^{\infty}$
estimates.
| arxiv topic:math.CV |
arxiv_dataset-1153903.4181 | Noiseless linear amplification via weak measurements
quant-ph
We discuss the recently introduced concept of non-deterministic noiseless
linear amplification, demonstrating that such an operation can only be
performed perfectly with vanishing probability of success. We show that a weak
measurement, which imprints the weak value of an observable of a pre-selected
and post-selected system onto a probe system, can be used to approximate
probabilistic noiseless amplification. This result may be applied to various
tasks in continuous variable quantum information, including entanglement
concentration, probabilistic cloning, and in quantum repeaters. We discuss the
application of our scheme to probabilistic cloning of weak coherent states.
| arxiv topic:quant-ph |
arxiv_dataset-1154903.4281 | Discovery of the Tungsten Isotopes
nucl-ex
Thirty-five tungsten isotopes have so far been observed; the discovery of
these isotopes is discussed. For each isotope a brief summary of the first
refereed publication, including the production and identification method, is
presented.
| arxiv topic:nucl-ex |
arxiv_dataset-1155903.4381 | Limitations of the Standard Gravitational Perfect Fluid Paradigm
gr-qc
We show that the standard perfect fluid paradigm is not necessarily a valid
description of a curved space steady state gravitational source. Simply by
virtue of not being flat, curved space geometries have to possess intrinsic
length scales, and such length scales can affect the fluid structure. For modes
of wavelength of order or greater than such scales eikonalized geometrical
optics cannot apply and rays are not geodesic. Covariantizing thus entails not
only the replacing of flat space functions by covariant ones, but also the
introduction of intrinsic scales that were absent in flat space. In principle
it is thus unreliable to construct the curved space energy-momentum tensor as
the covariant generalization of a geodesic-based flat spacetime energy-momentum
tensor. By constructing the partition function as an incoherent average over a
complete set of modes of a scalar field propagating in a curved space
background, we show that for the specific case of a static, spherically
symmetric geometry, the steady state energy-momentum tensor that ensues will in
general be of the form
$T_{\mu\nu}=(\rho+p)U_{\mu}U_{\nu}+pg_{\mu\nu}+\pi_{\mu\nu}$ where the
anisotropic $\pi_{\mu\nu}$ is a symmetric, traceless rank two tensor which
obeys $U^{\mu}\pi_{\mu\nu}=0$. Such a $\pi_{\mu\nu}$ type term is absent for an
incoherently averaged steady state fluid in a spacetime where there are no
intrinsic length scales, and in principle would thus be missed in a
covariantizing of a flat spacetime $T_{\mu\nu}$. While the significance of such
$\pi_{\mu\nu}$ type terms would need to be evaluated on a case by case basis,
through the use of kinetic theory we reassuringly find that the effect of such
$\pi_{\mu\nu}$ type terms is small for weak gravity stars where perfect fluid
sources are commonly used.
| arxiv topic:gr-qc |
arxiv_dataset-1156903.4481 | Dynamical generation and dynamical reconstruction
hep-ph
A definition of `dynamical generation', a hotly debated topic at present, is
proposed and its implications are discussed. This definition, in turn, leads to
a method allowing to distinguish in principle tetraquark and molecular states.
The different concept of `dynamical reconstruction' is also introduced and
applies to the generation of preexisting mesons (quark-antiquark, glueballs,
>...) via unitarization methods applied to low-energy effective Lagrangians.
Large $N_{c}$ arguments play an important role in all these investigations. A
simple toy model with two scalar fields is introduced to elucidate these
concepts. The large $N_{c}$ behavior of the parameters is chosen in order that
the two scalar fields behave as quark-antiquark mesons. When the heavier field
is integrated out, one is left with an effective Lagrangian with the lighter
field only. A unitarization method applied to the latter allows to
`reconstruct' the heavier `quarkonium-like' field, which was previously
integrated out. It is shown that a Bethe-Salpeter (BS) analysis is capable to
reproduce the preformed quark-antiquark state. However, when only the lowest
term of the effective Lagrangian is retained, the large $N_{c}$ limit of the
reconstructed state is not reproduced: instead of the correct large $N_{c}$
quarkonium limit, it fades out as a molecular state would do. Implications of
these results are presented: it is proposed that axial-vector, tensor and
(some) scalar mesons just above 1 GeV obtained via the BS approach from the
corresponding low-energy, effective Lagrangian in which only the lowest term is
kept, are quarkonia states, in agreement with the constituent quark model,
although they might fade away as molecular states in the large $N_{c}$ limit.
| arxiv topic:hep-ph |
arxiv_dataset-1157903.4581 | Localized Hardy Spaces $H^1$ Related to Admissible Functions on
RD-Spaces and Applications to Schr\"odinger Operators
math.CA math.FA
Let ${\mathcal X}$ be an RD-space, which means that ${\mathcal X}$ is a space
of homogenous type in the sense of Coifman and Weiss with the additional
property that a reverse doubling property holds in ${\mathcal X}$. In this
paper, the authors first introduce the notion of admissible functions $\rho$
and then develop a theory of localized Hardy spaces $H^1_\rho ({\mathcal X})$
associated with $\rho$, which includes several maximal function
characterizations of $H^1_\rho ({\mathcal X})$, the relations between $H^1_\rho
({\mathcal X})$ and the classical Hardy space $H^1({\mathcal X})$ via
constructing a kernel function related to $\rho$, the atomic decomposition
characterization of $H^1_\rho ({\mathcal X})$, and the boundedness of certain
localized singular integrals in $H^1_\rho({\mathcal X})$ via a finite atomic
decomposition characterization of some dense subspace of $H^1_\rho ({\mathcal
X})$. This theory has a wide range of applications. Even when this theory is
applied, respectively, to the Schr\"odinger operator or the degenerate
Schr\"odinger operator on $\rn$, or the sub-Laplace Schr\"odinger operator on
Heisenberg groups or connected and simply connected nilpotent Lie groups, some
new results are also obtained. The Schr\"odinger operators considered here are
associated with nonnegative potentials satisfying the reverse H\"older
inequality.
| arxiv topic:math.CA math.FA |
arxiv_dataset-1158903.4681 | Luminosity function and radial distribution of Milky Way Satellites in a
LCDM Universe
astro-ph.CO astro-ph.GA
We study the luminosity function and the radial distribution of satellite
galaxies within Milky Way sized haloes as predicted in Cold Dark Matter based
models of galaxy formation, making use of numerical N-body techniques as well
as three different semi-analytic model (SAMs) galaxy formation codes. We
extract merger trees from very high-resolution dissipationless simulations of
four Galaxy-sized DM haloes, and use these as common input for the
semi-analytic models. We present a detailed comparison of our predictions with
the observational data recently obtained on the Milky Way satellite luminosity
function (LF). We find that semi-analytic models with rather standard
astrophysical ingredients are able to reproduce the observed luminosity
function over six orders of magnitude in luminosity, down to magnitudes as
faint as M_V=-2. We also perform a comparison with the actual observed number
of satellites as a function of luminosity, by applying the selection criteria
of the SDSS survey to our simulations instead of correcting the observations
for incompleteness. Using this approach we again find good agreement for both
the luminosity and radial distributions of MW satellites. We investigate which
physical processes in our models are responsible for shaping the predicted
satellite LF, and find that tidal destruction, suppression of gas infall by a
photo-ionizing background, and supernova feedback all make important
contributions. We conclude that the number and luminosity of Milky Way
satellites can be naturally accounted for within the (Lambda) Cold Dark Matter
paradigm, and this should no longer be considered a problem.
| arxiv topic:astro-ph.CO astro-ph.GA |
arxiv_dataset-1159903.4781 | Nonseparably connected complete metric spaces
math.MG math.GR
A topological space is nonseparably connected if it is connected but all of
its connected separable subspaces are singletons. We show that each connected
first countable space is the image of a nonseparably connected complete metric
space under a continuous monotone hereditarily quotient map.
| arxiv topic:math.MG math.GR |
arxiv_dataset-1160903.4881 | Exact lattice supersymmetry
hep-lat hep-ph hep-th
We provide an introduction to recent lattice formulations of supersymmetric
theories which are invariant under one or more real supersymmetries at nonzero
lattice spacing. These include the especially interesting case of ${\cal N}=4$
SYM in four dimensions. We discuss approaches based both on twisted
supersymmetry and orbifold-deconstruction techniques and show their equivalence
in the case of gauge theories. The presence of an exact supersymmetry reduces
and in some cases eliminates the need for fine tuning to achieve a continuum
limit invariant under the full supersymmetry of the target theory. We discuss
open problems.
| arxiv topic:hep-lat hep-ph hep-th |
arxiv_dataset-1161903.4981 | Film Edge Nonlocal Spin Valves
cond-mat.mtrl-sci cond-mat.other
Spintronics is a new paradigm for integrated digital electronics. Recently
established as a niche for nonvolatile magnetic random access memory (MRAM), it
offers new functionality while demonstrating low power and high speed
performance. However, to reach high density spintronic technology must make a
transition to the nanometer scale. Prototype devices are presently made using a
planar geometry and have an area determined by the lithographic feature size,
currently about 100 nm. Here we present a new nonplanar geometry in which one
lateral dimension is given by a film thickness, the order of 10 nm. With this
new approach, cell sizes can shrink by an order of magnitude. The geometry is
demonstrated with a nonlocal spin valve, where we study devices with an
injector/detector separation much less than the spin diffusion length.
| arxiv topic:cond-mat.mtrl-sci cond-mat.other |
arxiv_dataset-1162903.5081 | Techniques for improved heavy particle searches with jet substructure
hep-ph
We present a generic method for improving the effectiveness of heavy particle
searches in hadronic channels at the Large Hadron Collider. By selectively
removing, or pruning, protojets from the substructure provided by a k_T-style
jet algorithm, we improve the mass resolution for heavy decays and decrease the
QCD background. We show that the protojets removed are typical of soft
radiation and underlying event contributions, and atypical of accurately
reconstructed heavy particles.
| arxiv topic:hep-ph |
arxiv_dataset-1163903.5181 | Numerical and Analytical Approach to the Quantum Dynamics of Two Coupled
Spins in Bosonic Baths
quant-ph
The quantum dynamics of a spin chain interacting with multiple bosonic baths
is described in a mixed Wigner-Heisenberg representation. The formalism is
illustrated by simulating the time evolution of the reduced density matrix of
two coupled spins, where each spin is also coupled to its own bath of harmonic
oscillators. In order to prove the validity of the approach, an analytical
solution in the Born-Markov approximation is found. The agreement between the
two methods is shown.
| arxiv topic:quant-ph |
arxiv_dataset-1164903.5281 | The ridge laboratory
nucl-th
Mechanisms proposed to explain the jet-related correlation of long range in
rapidity (the ridge) observed in high-energy heavy-ion collisions are reviewed.
Limitations of a model using the combined effect of transverse flow and a
direction bias of partons suffering energy loss are discussed. The influence of
the time scale of the correlation mechanism on the rapidity range is
investigated.
| arxiv topic:nucl-th |
arxiv_dataset-1165903.5381 | Non-Adiabatic Fluctuation in Measured Geometric Phase
quant-ph cond-mat.mes-hall
We study how the non-adiabatic effect causes the observable fluctuation in
the "geometric phase" for a two-level system, which is defined as the
experimentally measurable quantity in the adiabatic limit. From the Rabi's
exact solution to this model, we give a reasonable explanation to the
experimental discovery of phase fluctuation in the superconducting circuit
system [P. J. Leek, \textit{et al}., Science \textbf{318}, 1889 (2007)], which
seemed to be regarded as the conventional experimental error.
| arxiv topic:quant-ph cond-mat.mes-hall |
arxiv_dataset-1166903.5481 | Remarks on the lattice Green's Function for the anisotropic Face
Centered Cubic Lattice
cond-mat.other cond-mat.mes-hall
An expression for the Green's function (GF) of anisotropic face centered
cubic lattice is evaluated analytically and numerically for a single impurity
problem. The density of states (DOS), phase shift and scattering cross section
are expressed in terms of complete elliptic integrals of the first kink.
| arxiv topic:cond-mat.other cond-mat.mes-hall |
arxiv_dataset-1167904.0034 | CCS-Based Dynamic Logics for Communicating Concurrent Programs
cs.LO
This work presents three increasingly expressive Dynamic Logics in which the
programs are CCS processes (sCCS-PDL, CCS-PDL and XCCS-PDL). Their goal is to
reason about properties of concurrent programs and systems described using CCS.
In order to accomplish that, CCS's operators and constructions are added to a
basic modal logic in order to create dynamic logics that are suitable for the
description and verification of properties of communicating, concurrent and
non-deterministic programs and systems, in a similar way as PDL is used for the
sequential case. We provide complete axiomatizations for the three logics.
Unlike Peleg's Concurrent PDL with Channels, our logics have a simple Kripke
semantics, complete axiomatizations and the finite model property.
| arxiv topic:cs.LO |
arxiv_dataset-1168904.0134 | Unitary highest weight modules of locally affine Lie algebras
math.RT math.RA
Locally affine Lie algebras are generalizations of affine Kac--Moody algebras
with Cartan subalgebras of infinite rank whose root system is locally affine.
In this note we study a class of representations of locally affine algebras
generalizing integrable highest weight modules. In particular, we construct
such an integrable representation for each integral weight not vanishing on the
center and show that, over the complex numbers, we thus obtain unitary
representations w.r.t. a unitary real form.
We also use Yoshii's recent classification of locally affine root systems to
derive a classification of so-called minimal locally affine Lie algebras and
give realizations as twisted loop algebras.
| arxiv topic:math.RT math.RA |
arxiv_dataset-1169904.0234 | The impact of magnetic properties on atom-wall interaction
quant-ph
The Lifshitz-type formulas for the free energy and Casimir-Polder force
acting between an atom possessing a permanent magnetic moment and a wall made
of different materials are derived. Simple model allowing analytic results is
considered where the atomic magnetic susceptibility is frequency-independent
and wall is made of ideal metal. Numerical computations of the Casimir-Polder
force are performed for H atom interacting with walls made of ideal metal,
nonmagnetic (Au) and ferromagnetic (Fe) metals and of ferromagnetic dielectric.
It is shown that for the first three wall materials the inclusion of the
magnetic moment of an atom decreases and for the fourth material increases the
magnitude of the Casimir-Polder force.
| arxiv topic:quant-ph |
arxiv_dataset-1170904.0334 | Radiation thermo-chemical models of protoplanetary disks I. Hydrostatic
disk structure and inner rim
astro-ph.EP astro-ph.SR
This paper introduces a new disk code, called ProDiMo, to calculate the
thermo-chemical structure of protoplanetary disks and to interpret gas emission
lines from UV to sub-mm. We combine frequency-dependent 2D dust continuum
radiative transfer, kinetic gas-phase and UV photo-chemistry, ice formation,
and detailed non-LTE heating & cooling balance with the consistent calculation
of the hydrostatic disk structure. We include FeII and CO ro-vibrational line
heating/cooling relevant for the high-density gas close to the star, and apply
a modified escape probability treatment. The models are characterized by a high
degree of consistency between the various physical, chemical and radiative
processes, where the mutual feedbacks are solved iteratively. In application to
a T Tauri disk extending from 0.5AU to 500AU, the models are featured by a
puffed-up inner rim and show that the dense, shielded and cold midplane
(z/r<0.1, Tg~Td) is surrounded by a layer of hot (5000K) and thin (10^7 to 10^8
cm^-3) atomic gas which extends radially to about 10AU, and vertically up to
z/r~0.5. This layer is predominantly heated by the stellar UV (e.g.
PAH-heating) and cools via FeII semi-forbidden and OI 630nm optical line
emission. The dust grains in this "halo" scatter the star light back onto the
disk which impacts the photo-chemistry. The more distant regions are
characterized by a cooler flaring structure. Beyond 100AU, Tgas decouples from
Tdust even in the midplane and reaches values of about Tg~2Td. Our models show
that the gas energy balance is the key to understand the vertical disk
structure. Models calculated with the assumption Tg=Td show a much flatter disk
structure.
| arxiv topic:astro-ph.EP astro-ph.SR |
arxiv_dataset-1171904.0434 | On the ill-posedness of the Prandtl equation
math.AP
The concern of this paper is the Cauchy problem for the Prandtl equation.
This problem is known to be well-posed for analytic data, or for data with
monotonicity properties. We prove here that it is linearly ill-posed in Sobolev
type spaces. The key of the analysis is the construction, at high tangential
frequencies, of unstable quasimodes for the linearization around solutions with
non-degenerate critical points. Interestingly, the strong instability is due to
vicosity, which is coherent with well-posedness results obtained for the
inviscid version of the equation. A numerical study of this instability is also
provided.
| arxiv topic:math.AP |
arxiv_dataset-1172904.0534 | Theory of Carry Value Transformation (CVT) and its Application in
Fractal formation
cs.DM
In this paper the theory of Carry Value Transformation (CVT) is designed and
developed on a pair of n-bit strings and is used to produce many interesting
patterns. One of them is found to be a self-similar fractal whose dimension is
same as the dimension of the Sierpinski triangle. Different construction
procedures like L-system, Cellular Automata rule, Tilling for this fractal are
obtained which signifies that like other tools CVT can also be used for the
formation of self-similar fractals. It is shown that CVT can be used for the
production of periodic as well as chaotic patterns. Also, the analytical and
algebraic properties of CVT are discussed. The definition of CVT in
two-dimension is slightly modified and its mathematical properties are
highlighted. Finally, the extension of CVT and modified CVT (MCVT) are done in
higher dimensions.
| arxiv topic:cs.DM |
arxiv_dataset-1173904.0634 | Limits over categories of extensions
math.CT math.KT
We consider limits over categories of extensions and show how certain
well-known functors on the category of groups turn out as such limits. We also
discuss higher (or derived) limits over categories of extensions.
| arxiv topic:math.CT math.KT |
arxiv_dataset-1174904.0734 | Short proofs of theorems of Mirsky and Horn on diagonals and eigenvalues
of matrices
math.FA math.OA quant-ph
A theorem of Mirsky provides necessary and sufficient conditions for the
existence of an N-square complex matrix with prescribed diagonal entries and
prescribed eigenvalues. We give a simple inductive proof of this theorem.
| arxiv topic:math.FA math.OA quant-ph |
arxiv_dataset-1175904.0834 | Solitary waves for the Hartree equation with a slowly varying potential
math.AP math-ph math.MP
We study the Hartree equation with a slowly varying smooth potential, $V(x) =
W(hx)$, and with an initial condition which is $\epsilon \le \sqrt h$ away in
$H^1$ from a soliton. We show that up to time $|\log h|/h$ and errors of size
$\epsilon + h^2$ in $H^1$, the solution is a soliton evolving according to the
classical dynamics of a natural effective Hamiltonian. This result is based on
methods of Holmer-Zworski, who prove a similar theorem for the Gross-Pitaevskii
equation, and on spectral estimates for the linearized Hartree operator
recently obtained by Lenzmann. We also provide an extension of the result of
Holmer-Zworski to more general inital conditions.
| arxiv topic:math.AP math-ph math.MP |
arxiv_dataset-1176904.0934 | Inflaton in R-dependent potential
hep-ph gr-qc
We consider a non-minimally coupled inflaton, in a higher order curvature
background, leading to a potential which evolves with the curvature scalar of
the Universe, and which describes two regimes. The first one is a de Sitter
phase, where the potential is static, and an exact exponential solution is
found for the inflaton. The second regime, triggered by the inflaton reaching a
threshold, leads to a power-law expansion, during which the potential becomes
flat, quickly enough for the inflaton never to reach the minimum of the initial
symmetry breaking potential. This scenario is an alternative to the inflaton
oscillating about a minimum of the potential, and where preheating is a
consequence of the flattening of the potential during the power-law expanding
phase.
| arxiv topic:hep-ph gr-qc |
arxiv_dataset-1177904.1034 | Possibility of generalized monogamy relations for multipartite
entanglement beyond three qubits
quant-ph cond-mat.other
We discuss the possibility to interpret the residual entanglement for more
than three qubits in terms of distributed multipartite entanglement, or, in
other words, possible extensions of the Coffman-Kundu-Wootters monogamy
equality to higher qubit numbers. Existing knowledge on entanglement in
multipartite systems puts narrow constraints on the form of such extensions. We
study various examples for families of pure four-qubit states for which the
characterization of three-qubit and four-qubit entanglement in terms of
polynomial invariants is known. These examples indicate that, although families
with such extensions do exist, a generalized monogamy equality cannot be found
along those lines.
| arxiv topic:quant-ph cond-mat.other |
arxiv_dataset-1178904.1134 | Finite Size Effects in Equations of State under non-trivial Boundary
Conditions
math-ph cond-mat.stat-mech math.MP quant-ph
We study free particles in a one-dimensional box with combinations of two
types of boundary conditions: the Dirichlet condition and a one-parameter
family of quasi-Neumann conditions at the two walls. We calculate energy
spectra approximately and obtain equations of state having the same
(one-dimensional) volume dependence as van der Waals equations of state. The
dependence of the equations of state is examined for particles obeying
Maxwell-Boltzmann, Bose-Einstein, or Fermi-Dirac statistics. Our results
suggest that the deviation from ideal gas may also be realized as finite size
effects due to the interaction between the particles and the walls.
| arxiv topic:math-ph cond-mat.stat-mech math.MP quant-ph |
arxiv_dataset-1179904.1234 | Mapping the evolution of scientific fields
physics.soc-ph cs.DL cs.IR
Despite the apparent cross-disciplinary interactions among scientific fields,
a formal description of their evolution is lacking. Here we describe a novel
approach to study the dynamics and evolution of scientific fields using a
network-based analysis. We build an idea network consisting of American
Physical Society Physics and Astronomy Classification Scheme (PACS) numbers as
nodes representing scientific concepts. Two PACS numbers are linked if there
exist publications that reference them simultaneously. We locate scientific
fields using a community finding algorithm, and describe the time evolution of
these fields over the course of 1985-2006. The communities we identify map to
known scientific fields, and their age depends on their size and activity. We
expect our approach to quantifying the evolution of ideas to be relevant for
making predictions about the future of science and thus help to guide its
development.
| arxiv topic:physics.soc-ph cs.DL cs.IR |
arxiv_dataset-1180904.1334 | Horava-Lifshitz Cosmology
hep-th gr-qc
The cosmological equations suggested by the non-relativistic renormalizable
gravitational theory proposed by Ho\v{r}ava are considered. It is pointed out
that the early universe cosmology has features that may give an alternative to
inflation and the theory may be able to escape singularities.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-1181904.1434 | Understanding local Dwarf Spheroidals and their scaling relations under
MOdified Newtonian Dynamics
astro-ph.GA astro-ph.CO
We use a specific form of the interpolation function in the MOND formalism,
which optimally accounts for the internal structure of dwarf spheroidal (dSph)
galaxies, to explore the consequences it has on the scaling relations seen in
these systems.}} {{The particular form of the interpolation function we used
leads to a law of gravity that does not degrade the good fit of the MOND
proposal on galactic scales, and in fact, slightly improves the accordance with
observations at dSph scales. This formalism yields a good description of
gravitational phenomena without the need of invoking any still undetected and
hypothetically dominant dark matter, in the weak field regime probed by local
dSph galaxies.}} {{Isothermal equilibrium density profiles then yield projected
surface density profiles for the local dSph galaxies in very good agreement
with observational determinations, for values of the relevant parameters as
inferred from recent observations of these Galactic satellites. The observed
scaling relations for these systems are also naturally accounted for within the
proposed scheme, including a previously unrecognised correlation of the
inferred mass-to-light ratios of local dSph's with the ages of their stellar
populations, which is natural in modified gravity schemes in the absence of
dark matter.}} {The results shed some light on the form that the MOND
interpolating function may have in the most challenging regime, which occurs at
moderate accelerations and intermediate mass--weighted lengths.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-1182904.1534 | Estimating nonlinearities in twophase flow in porous media
cs.NA math.AP physics.class-ph
In order to analyze numerically inverse problems several techniques based on
linear and nonlinear stability analysis are presented. These techniques are
illustrated on the problem of estimating mobilities and capillary pressure in
one-dimensional two-phase displacements in porous media that are performed in
laboratories. This is an example of the problem of estimating nonlinear
coefficients in a system of nonlinear partial differential equations.
| arxiv topic:cs.NA math.AP physics.class-ph |
arxiv_dataset-1183904.1634 | Neutron-irradiation effects in LaO0.9F0.1FeAs superconductor
cond-mat.supr-con cond-mat.other
The effect of atomic disorder induced by neutrons irradiation on
superconducting and normal state properties of polycrystalline LaFeAsO_0.9F_0.1
was investigated. The irradiation of the sample by a moderate neutron fluence F
= 1.6*1019 cm^-2 at Tirr = 50 +- 10 C leads to the suppression of
superconductivity which recovers almost completely after annealing at
temperatures Tann < 750 C. It is shown that the reduction of superconducting
transition temperature Tc under atomic disordering is not determined solely by
the value of Hall concentration nH, i.e. doping level, but is governed by the
reduction of electronic relaxation time. This behavior can be described
qualitatively by universal Abrikosov-Gorkov equation which presents evidence on
the anomalous type of electrons pairing in Fe-based superconductors.
| arxiv topic:cond-mat.supr-con cond-mat.other |
arxiv_dataset-1184904.1734 | On the volume conjecture for classical spin networks
math.GT gr-qc hep-th math.CO
We prove an upper bound for the evaluation of all classical SU(2) spin
networks conjectured by Garoufalidis and van der Veen. This implies one half of
the analogue of the volume conjecture which they proposed for classical spin
networks. We are also able to obtain the other half, namely, an exact
determination of the spectral radius, for the special class of generalized drum
graphs. Our proof uses a version of Feynman diagram calculus which we developed
as a tool for the interpretation of the symbolic method of classical invariant
theory, in a manner which is rigorous yet true to the spirit of the classical
literature.
| arxiv topic:math.GT gr-qc hep-th math.CO |
arxiv_dataset-1185904.1834 | Limits on Nonstandard Forces in the Submicrometer Range
hep-ex
We report the search for a nonstandard force by measuring the Casimir forces
in the 0.48--6.5 $\mu$m range. By comparing the data and the theory of the
Casimir force, we have obtained constraints for the parameter $\alpha$ of the
Yukawa-type deviations from Newtonian gravity. The obtained limits are more
stringent than previous limits in the 1.0--2.9 $\mu$m range. Furthermore, we
have obtained lower limits for the fundamental scale $M_{*}$ for gauged baryon
number in the bulk. In particular, for six extra dimensions, the limits on
$M_{*}$ are stringent in the range $6.5\times10^{-6}<\rho<2.5\times10^{-4}$.
| arxiv topic:hep-ex |
arxiv_dataset-1186904.1934 | Study of thickness dependent density in ultrathin water soluble polymer
films
cond-mat.soft cond-mat.mtrl-sci
Density of the polyacrylamide ultrathin films has been studied using X-ray
reflectivity technique. Two sources (one powder and another aqueous solution)
of polyacrylamide were used to prepare spin coated films on silicon substrate.
Light scattering measurements show that the polymer chains were unentangled in
a concentrated (4 mg/ml) as well as in a dilute (2 mg/ml) solution prepared
from the powder, whereas the solution (4 mg/ml) prepared by diluting the
solution source shows entangled chain morphology. Three sets of films of
different thicknesses were prepared using the three solutions by spin coating
on silicon substrates. Comparison of X-ray reflectivity data for as prepared
and dry films reveals that the shrinkage of the films decreases with increasing
thickness. Average electron densities of the films were found to follow a trend
of higher density for thinner films with a maximum increase of about 12%
compared to the bulk. The densities of all the films irrespective of the nature
of entanglement and concentration of their source were found to increase with
spin speed of coating and attain saturation at higher speed. Absence of
correlation between shrinkage and density data and the fact that the densities
of all the films follow a master curve irrespective of their origin suggest
that the higher density of the films result from the higher orientation of
chains as a consequence of an interplay between stretching and stronger
attractive interactions of polar nature.
| arxiv topic:cond-mat.soft cond-mat.mtrl-sci |
arxiv_dataset-1187904.2034 | Near-threshold photoproduction of $\Lambda(1520)$ from protons and
deuterons
nucl-ex
Photoproduction of $\Lambda$(1520) with liquid hydrogen and deuterium targets
was examined at photon energies below 2.4 GeV in the SPring-8 LEPS experiment.
For the first time, the differential cross sections were measured at low
energies and with a deuterium target. A large asymmetry of the production cross
sections from protons and neutrons was observed at backward K$^{+/0}$ angles.
This suggests the importance of the contact term, which coexists with t-channel
K exchange under gauge invariance. This interpretation was compatible with the
differential cross sections, decay asymmetry, and photon beam asymmetry
measured in the production from protons at forward K$^+$ angles.
| arxiv topic:nucl-ex |
arxiv_dataset-1188904.2134 | Fluctuating nanomechanical systems in a high finesse optical microcavity
physics.optics
Confining a laser field between two high reflectivity mirrors of a
high-finesse cavity can increase the probability of a given cavity photon to be
scattered by an atom traversing the confined photon mode. This enhanced
coupling between light and atoms is successfully employed in cavity quantum
electrodynamics experiments and led to a very prolific research in quantum
optics. The idea of extending such experiments to sub-wavelength sized
nanomechanical systems has been recently proposed in the context of optical
cavity cooling. Here we present an experiment involving a single nanorod
consisting of about 10^9 atoms precisely positioned to plunge into the confined
mode of a miniature high finesse Fabry-Perot cavity. We show that the optical
transmission of the cavity is affected not only by the static position of the
nanorod but also by its vibrational fluctuation. While an imprint of the
vibration dynamics is directly detected in the optical transmission,
back-action of the light field is also anticipated to quench the nanorod
Brownian motion. This experiment shows the first step towards optical cavity
controlled dynamics of mechanical nanostructures and opens up new perspectives
for sensing and manipulation of optomechanical nanosystems.
| arxiv topic:physics.optics |
arxiv_dataset-1189904.2234 | Beta-gamma systems and the deformations of the BRST operator
hep-th gr-qc math-ph math.MP math.QA
We describe the relation between simple logarithmic CFTs associated with
closed and open strings, and their "infinite metric" limits, corresponding to
the beta-gamma systems. This relation is studied on the level of the BRST
complex: we show that the consideration of metric as a perturbation leads to a
certain deformation of the algebraic operations of the Lian-Zuckerman type on
the vertex algebra, associated with the beta-gamma systems. The Maurer-Cartan
equations corresponding to this deformed structure in the quasiclassical
approximation lead to the nonlinear field equations. As an explicit example, we
demonstrate, that using this construction, Yang-Mills equations can be derived.
This gives rise to a nontrivial relation between the Courant-Dorfman algebroid
and homotopy algebras emerging from the gauge theory. We also discuss possible
algebraic approach to the study of beta-functions in sigma-models.
| arxiv topic:hep-th gr-qc math-ph math.MP math.QA |
arxiv_dataset-1190904.2334 | The Precision Array for Probing the Epoch of Reionization: 8 Station
Results
astro-ph.CO
We are developing the Precision Array for Probing the Epoch of Reionization
(PAPER) to detect 21cm emission from the early Universe, when the first stars
and galaxies were forming. We describe the overall experiment strategy and
architecture and summarize two PAPER deployments: a 4-antenna array in the
low-RFI environment of Western Australia and an 8-antenna array at our
prototyping site in Green Bank, WV. From these activities we report on system
performance, including primary beam model verification, dependence of system
gain on ambient temperature, measurements of receiver and overall system
temperatures, and characterization of the RFI environment at each deployment
site.
We present an all-sky map synthesized between 139 MHz and 174 MHz using data
from both arrays that reaches down to 80 mJy (4.9 K, for a beam size of 2.15e-5
steradians at 154 MHz), with a 10 mJy (620 mK) thermal noise level that
indicates what would be achievable with better foreground subtraction. We
calculate angular power spectra ($C_\ell$) in a cold patch and determine them
to be dominated by point sources, but with contributions from galactic
synchrotron emission at lower radio frequencies and angular wavemodes. Although
the cosmic variance of foregrounds dominates errors in these power spectra, we
measure a thermal noise level of 310 mK at $\ell=100$ for a 1.46-MHz band
centered at 164.5 MHz. This sensitivity level is approximately three orders of
magnitude in temperature above the level of the fluctuations in 21cm emission
associated with reionization.
| arxiv topic:astro-ph.CO |
arxiv_dataset-1191904.2434 | Collision of Multimode Dromions and a Firewall in the Two Component Long
Wave Short Wave Resonance Interaction Equation
nlin.PS nlin.SI
In this paper, we investigate the two component long wave short wave
resonance interaction (2CLSRI) equation and show that it admits the Painleve
property. We then suitably exploit the recently developed truncated Painleve
approach to generate exponentially localized solutions for the short wave
components $S^{(1)}$ and $S^{(2)}$ while the long wave L admits line soliton
only. The exponentially localized solutions driving the short waves $S^{(1)}$
and $S^{(2)}$ in the y direction are endowed with different energies
(intensities) and are called "multimode dromions". We also observe that the
multimode dromions suffer intramodal inelastic collision while the existence of
a firewall across the modes prevents the switching of energy between the modes.
| arxiv topic:nlin.PS nlin.SI |
arxiv_dataset-1192904.2534 | Indirect Searches for $Z'$-like Resonances at the LHC
hep-ph
We explore the possibility of indirectly observing the effects of $Z'$-like
particles with electroweak strength couplings in the Drell-Yan channel at the
LHC with masses above the resonance direct search reach. We find that, mostly
due to statistical limitations, this is very unlikely in almost all classes of
models independently of the spin of the resonance. Not unexpectedly, the one
possible exception to this general result is the case of degenerate
Kaluza-Klein (KK) excitations of the photon and $Z$ that occur in some
extra-dimensional models. In this special case, the strong destructive
interference with the Standard Model (SM) exchanges below the resonance mass
leads to a well-known significant suppression of the cross section and thus
increased sensitivity to this particular new physics scenario.
| arxiv topic:hep-ph |
arxiv_dataset-1193904.2634 | Model Error Correction for Linear Methods of Reversible Radioligand
Binding Measurements in PET Studies
q-bio.QM
Graphical analysis methods are widely used in positron emission tomography
quantification because of their simplicity and model independence. But they
may, particularly for reversible kinetics, lead to bias in the estimated
parameters. The source of the bias is commonly attributed to noise in the data.
Assuming a two-tissue compartmental model, we investigate the bias that
originates from model error. This bias is an intrinsic property of the
simplified linear models used for limited scan durations, and it is exaggerated
by random noise and numerical quadrature error. Conditions are derived under
which Logan's graphical method either over- or under-estimates the distribution
volume in the noise-free case. The bias caused by model error is quantified
analytically. The presented analysis shows that the bias of graphical methods
is inversely proportional to the dissociation rate. Furthermore, visual
examination of the linearity of the Logan plot is not sufficient for
guaranteeing that equilibrium has been reached. A new model which retains the
elegant properties of graphical analysis methods is presented, along with a
numerical algorithm for its solution. We perform simulations with the fibrillar
amyloid-beta radioligand [11C] benzothiazole-aniline using published data from
the University of Pittsburgh and Rotterdam groups. The results show that the
proposed method significantly reduces the bias due to model error. Moreover,
the results for data acquired over a 70 minutes scan duration are at least as
good as those obtained using existing methods for data acquired over a 90
minutes scan duration.
| arxiv topic:q-bio.QM |
arxiv_dataset-1194904.2734 | The category $\mathcal{O}$ for a general Coxeter system
math.RT
We study the category $\mathcal{O}$ for a general Coxeter system using a
formulation of Fiebig. The translation functors, the Zuckerman functors and the
twisting functors are defined. We prove the fundamental properties of these
functors, the duality of Zuckerman functor and generalization of Verma's result
about homomorphisms between Verma modules.
| arxiv topic:math.RT |
arxiv_dataset-1195904.2834 | Tropical and algebraic curves with multiple points
math.AG
Patchworking theorems serve as a basic element of the correspondence between
tropical and algebraic curves, which is a core of the tropical enumerative
geometry. We present a new version of a patchworking theorem which relates
plane tropical curves with complex and real algebraic curves having prescribed
multiple points. It can be used to compute Welschinger invariants of non-toric
Del Pezzo surfaces.
| arxiv topic:math.AG |
arxiv_dataset-1196904.2934 | Desperately Seeking Intermediate-Mass Black Holes
hep-th
Observational searches for Intermediate Mass Black Holes (IMBHs), defined to
have masses between 30 and 300,000 solar masses, provide limits which allow up
to ten percent of what is presently identified as halo dark matter to be in the
form of IMBHs. These concentrate entropy so efficiently that the halo
contribution can be bigger than the core supermassive black hole. Formation of
IMBHs is briefly discussed.
| arxiv topic:hep-th |
arxiv_dataset-1197904.3034 | Comment on The Rise of Semiconductor Spintronics
cond-mat.mes-hall
I argue that most of the key experiments that have born semiconductor
spintronics were done and published earlier than the papers cited in the Nature
Physics, 4 S20 (2008) milestone article (http://www.nature.com/milestones/spin,
milestone 23).
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-1198904.3134 | Decoupling of the superconducting and magnetic (structural) phase
transitions in electron-doped BaFe2As2
cond-mat.supr-con
Study and comparison of over 30 examples of electron doped BaFe2As2 for
transition metal (TM) = Co, Ni, Cu, and (Co/Cu mixtures) have lead to an
understanding that the suppression of the structural/antiferromagnetic phase
transition to low enough temperature in these compounds is a necessary
condition for superconductivity, but not a sufficient one. Whereas the
structural/antiferromagnetic transitions are suppressed by the number of TM
dopant ions (or changes in the c-axis) the superconducting dome exists over a
limited range of values of the number of electrons added by doping (or values
of the {a/c} ratio). By choosing which combination of dopants are used we can
change the relative positions of the upper phase lines and the superconducting
dome, even to the extreme limit of suppressing the upper structural and
magnetic phase transitions without the stabilization of low temperature
superconducting dome.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-1199904.3234 | Controlled nanostructures at La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ thin film
surfaces formed by STM lithography
cond-mat.mes-hall cond-mat.mtrl-sci
Nanoscale lithography on La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) thin film
surfaces has been performed by scanning tunneling microscopy under ambient
conditions. From line-etching experiments we found that the line depth is
increasing in a step-wise fashion with increasing bias voltage as well as with
decreasing scan speed. On average, the depth of the etched lines is an integral
multiple of the LSMO out-of-plane lattice constant about 0.4 nm. A minimum wall
thickness of 1.5 nm was obtained between etched lines. We have utilized the
ability to control the etched line depths to create complicated inverse-pyramid
nanostructure. Our work shows the feasibility of using STM lithography to
create controllable and complex nanoscale structures in LSMO thin film.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
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