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arxiv_dataset-700806.3987 | Multi-Lepton Production at High Transverse Momenta in ep Collisions at
HERA
hep-ex
Processes leading to a final state with at least two high transverse momentum
leptons (electrons or muons) are studied using the full ep data sample
collected by the H1 experiment at HERA. The data correspond to an integrated
luminosity of 463 pb-1. Di-lepton and tri-lepton event classes are
investigated. Cross sections of the production of e+e- and mu+mu- pairs are
derived in a restricted phase space dominated by photon-photon collisions. In
general, good agreement is found with Standard Model predictions. Events are
observed with a total scalar sum of lepton transverse momenta above 100 GeV
where the Standard Model expectation is low. In this region, combining
di-lepton and tri-lepton classes, five events are observed in e+p collisions,
compared to a Standard Model expectation of 0.96+-0.12, while no such event is
observed in e-p data for 0.64+-0.09 expected.
| arxiv topic:hep-ex |
arxiv_dataset-701806.4087 | Planetesimal Accretion in Binary Systems: The Effects of Gas Dissipation
astro-ph
Currently, one of major problems concerning planet formation theory in close
binary systems is, the strong perturbation from the companion star can increase
relative velocities ($\triangle V$) of planetesimals around the primary and
thus hinder their growth. According to previous studies, while gas drag can
reduce the $\triangle V$ between bodies of the same sizes by forcing orbital
alignment to planetesimals, it increases the $\triangle V$ among bodies of
different sizes. In this paper, focusing on the $\gamma$ Cephei binary system,
we propose a mechanism that can overcome this difficulty. We show that in a
dissipating gas disk (with a typical dissipating timescale of $\sim 10^5-10^6$
years), all the planetesimals eventually converge towards the same forced
orbits regardless of their sizes, leading to much lower impact velocities among
them. These $\triangle V$ decrease processes progressively increase net mass
accretion and even trigger runaway growth for large bodies (radius $>15$ km).
The effect of size distribution of planetesimals is discussed, and found to be
one of the dominant factors that determine the outcome of collisional
evolution. Anyway, it can be concluded that by including the gas dissipation in
the early stage of disk evolution, the conditions for planetesimal accretion
become much better, and the process from planetesimal to planet-embryo can be
carried out in close binary systems like $\gamma$ Cephei.
| arxiv topic:astro-ph |
arxiv_dataset-702806.4187 | Intermediate Mass Black Hole Induced Quenching of Mass Segregation in
Star Clusters
astro-ph
In many theoretical scenarios it is expected that intermediate-mass black
holes (IMBHs, with masses M ~ 100-10000 solar masses) reside at the centers of
some globular clusters. However, observational evidence for their existence is
limited. Several previous numerical investigations have focused on the impact
of an IMBH on the cluster dynamics or brightness profile. Here we instead
present results from a large set of direct N-body simulations including single
and binary stars. These show that there is a potentially more detectable IMBH
signature, namely on the variation of the average stellar mass between the
center and the half-light radius. We find that the existence of an IMBH
quenches mass segregation and causes the average mass to exhibit only modest
radial variation in collisionally relaxed star clusters. This differs from when
there is no IMBH. To measure this observationally requires high resolution
imaging at the level of that already available from the Hubble Space Telescope
(HST) for the cores of a large sample of galactic globular clusters. With a
modest additional investment of HST time to acquire fields around the
half-light radius, it will be possible to identify the best candidate clusters
to harbor an IMBH. This test can be applied only to globulars with a half-light
relaxation time less than or equal to 1 Gyr, which is required to guarantee
efficient energy equipartition due to two-body relaxation.
| arxiv topic:astro-ph |
arxiv_dataset-703806.4287 | Subwavelength microscope that uses frequency scanning for image
reconstruction
physics.optics physics.ins-det
A new principle of subwavelength imaging based on frequency scanning is
considered. It is shown that it is possible to reconstruct the spatial profile
of an external field exciting an array (or coupled arrays) of
subwavelength-sized resonant particles with a frequency scan over the whole
band of resonating array modes. During the scan it is enough to measure and
store the values of the near field at one or at most two points. After the scan
the distribution of the near field can be reconstructed with simple
post-processing. The proposed near-field microscope has no moving parts.
| arxiv topic:physics.optics physics.ins-det |
arxiv_dataset-704806.4387 | The Late Stellar Assembly of Massive Cluster Galaxies Via Major Merging
astro-ph
We present multi-wavelength observations of the brightest galaxies in four
X-ray luminous groups at z~0.37 that will merge to form a cluster comparable in
mass to Coma. Ordered by increasing stellar mass, the four brightest group
galaxies (BGGs) present a time sequence where BGG-1, 2, and 3 are in merging
systems and BGG-4 is a massive remnant [M(stars)=6.7x10^(11) Msun]. BGG-1 and 2
have bright, gravitationally bound companions and BGG-3 has two nuclei
separated by only 2.5 kpc, thus merging at z<0.5 increases the BGG mass by >40%
(merging timescale<2 Gyr) and V-band luminosity by ~0.4 mag. The BGGs'
rest-frame (B-V) colors correspond to stellar ages of >3 Gyr, and their tight
scatter in (B-V) color [sigma(BV)=0.032] confirms they formed the bulk of their
stars at z>0.9. Optical spectroscopy shows no signs of recent (<1.5 Gyr) or
ongoing star formation. Only two BGGs are weakly detected at 24 microns, and
X-ray and optical data indicate the emission in BGG-2 is due to an AGN. All
four BGGs and their companions are early-type (bulge-dominated) galaxies, and
they are embedded in diffuse stellar envelopes up to ~140 kpc across. The four
BGG systems must evolve into the massive, red, early-type galaxies dominating
local clusters. Our results show that: 1) massive galaxies in groups and
clusters form via dissipationless merging; and 2) the group environment is
critical for this process.
| arxiv topic:astro-ph |
arxiv_dataset-705806.4487 | Confinement of matroid representations to subsets of partial fields
math.CO math.RA
Let M be a matroid representable over a (partial) field P and B a matrix
representable over a sub-partial field P' of P. We say that B confines M to P'
if, whenever a P-representation matrix A of M has a submatrix B, A is a scaled
P'-matrix. We show that, under some conditions on the partial fields, on M, and
on B, verifying whether B confines M to P' amounts to a finite check. A
corollary of this result is Whittle's Stabilizer Theorem.
A combination of the Confinement Theorem and the Lift Theorem from
arXiv:0804.3263 leads to a short proof of Whittle's characterization of the
matroids representable over GF(3) and other fields.
We also use a combination of the Confinement Theorem and the Lift Theorem to
prove a characterization, in terms of representability over partial fields, of
the 3-connected matroids that have k inequivalent representations over GF(5),
for k = 1, ..., 6.
Additionally we give, for a fixed matroid M, an algebraic construction of a
partial field P_M and a representation A over P_M such that every
representation of M over a partial field P is equal to f(A) for some
homomorphism f:P_M->P. Using the Confinement Theorem we prove an algebraic
analog of the theory of free expansions by Geelen et al.
| arxiv topic:math.CO math.RA |
arxiv_dataset-706806.4587 | The HARPS search for southern extra-solar planets. XIII. A planetary
system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)
astro-ph
This paper reports on the detection of a planetary system with three
Super-Earths orbiting HD40307. HD40307 is a K2V metal-deficient star at a
distance of only 13 parsec, part of the HARPS GTO high-precision planet-search
programme. The three planets on circular orbits have very low minimum masses of
respectively 4.2, 6.9 and 9.2 Earth masses and periods of 4.3, 9.6 and 20.5
days. The planet with the shortest period is the lightest planet detected
to-date orbiting a main sequence star. The detection of the correspondingly low
amplitudes of the induced radial-velocity variations is completely secured by
the 135 very high-quality HARPS observations illustrated by the radial-velocity
residuals around the 3-Keplerian solution of only 0.85 m/s. Activity and
bisector indicators exclude any significant perturbations of stellar intrinsic
origin, which supports the planetary interpretation. Contrary to most
planet-host stars, HD40307 has a marked sub-solar metallicity ([Fe/H]=-0.31),
further supporting the already raised possibility that the occurrence of very
light planets might show a different dependence on host star's metallicity
compared to the population of gas giant planets. In addition to the 3 planets
close to the central star, a small drift of the radial-velocity residuals
reveals the presence of another companion in the system the nature of which is
still unknown.
| arxiv topic:astro-ph |
arxiv_dataset-707806.4687 | Remnant inequalities and doubly-twisted conjugacy in free groups
math.AT math.GR
We give two results for computing doubly-twisted conjugacy relations in free
groups with respect to homomorphisms $\phi$ and $\psi$ such that certain
remnant words from $\phi$ are longer than the images of generators under
$\psi$.
Our first result is a remnant inequality condition which implies that two
words $u$ and $v$ are not doubly-twisted conjugate. Further we show that if
$\psi$ is given and $\phi$, $u$, and $v$ are chosen at random, then the
probability that $u$ and $v$ are not doubly-twisted conjugate is 1. In the
particular case of singly-twisted conjugacy, this means that if $\phi$, $u$,
and $v$ are chosen at random, then $u$ and $v$ are not in the same
singly-twisted conjugacy class with probability 1.
Our second result generalizes Kim's "bounded solution length". We give an
algorithm for deciding doubly-twisted conjugacy relations in the case where
$\phi$ and $\psi$ satisfy a similar remnant inequality. In the particular case
of singly-twisted conjugacy, our algorithm suffices to decide any twisted
conjugacy relation if $\phi$ has remnant words of length at least 2.
As a consequence of our generic properties we give an elementary proof of a
recent result of Martino, Turner, and Ventura, that computes the densities of
injective and surjective homomorphisms from one free group to another. We
further compute the expected value of the density of the image of a
homomorphism.
| arxiv topic:math.AT math.GR |
arxiv_dataset-708806.4787 | Locality and Bounding-Box Quality of Two-Dimensional Space-Filling
Curves
cs.CG cs.DB
Space-filling curves can be used to organise points in the plane into
bounding-box hierarchies (such as R-trees). We develop measures of the
bounding-box quality of space-filling curves that express how effective
different space-filling curves are for this purpose. We give general lower
bounds on the bounding-box quality measures and on locality according to
Gotsman and Lindenbaum for a large class of space-filling curves. We describe a
generic algorithm to approximate these and similar quality measures for any
given curve. Using our algorithm we find good approximations of the locality
and the bounding-box quality of several known and new space-filling curves.
Surprisingly, some curves with relatively bad locality by Gotsman and
Lindenbaum's measure, have good bounding-box quality, while the curve with the
best-known locality has relatively bad bounding-box quality.
| arxiv topic:cs.CG cs.DB |
arxiv_dataset-709806.4887 | Visualization Drivers for Geant4
physics.ins-det hep-ex
This document is on Geant4 visualization tools (drivers), evaluating pros and
cons of each option, including recommendations on which tools to support at
Fermilab for different applications{\cite{Daniel}}.
Four visualization drivers are evaluated. They are OpenGL, HepRep, DAWN and
VRML. They all have good features, OpenGL provides graphic output with out an
intermediate file! HepRep provides menus to assist the user. DAWN provides high
quality plots and even for large files produces output quickly. VRML uses the
smallest disk space for intermediate files.
Large experiments at Fermilab will want to write their own display. They
should proceed to make this display graphics independent. Medium experiment
will probably want to use HepRep because of it's menu support. Smaller scale
experiments will want to use OpenGL in the spirit of having immediate response,
good quality output and keeping things simple.
| arxiv topic:physics.ins-det hep-ex |
arxiv_dataset-710807.0007 | Finding Large Clique Minors is Hard
cs.DM
We prove that it is NP-complete, given a graph G and a parameter h, to
determine whether G contains a complete graph K_h as a minor.
| arxiv topic:cs.DM |
arxiv_dataset-711807.0107 | Dependence of the liquid-vapor surface tension on the range of
interaction: a test of the law of corresponding states
cond-mat.stat-mech cond-mat.soft
The planar surface tension of coexisting liquid and vapor phases of a fluid
of Lennard-Jones atoms is studied as a function of the range of the potential
using both Monte Carlo simulations and Density Functional Theory. The
interaction range is varied from $r_c^* = 2.5$ to $r_c^* = 6$ and the surface
tension is determined for temperatures ranging from $T^* = 0.7$ up to the
critical temperature in each case. The results are shown to be consistent with
previous studies. The simulation data are well-described by Guggenheim's law of
corresponding states but the agreement of the theoretical results depends on
the quality of the bulk equation of state.
| arxiv topic:cond-mat.stat-mech cond-mat.soft |
arxiv_dataset-712807.0207 | Cosmic Jerk, Snap and Beyond
gr-qc astro-ph hep-th
We clarify the procedure for expressing the Friedmann equation in terms of
directly measurable cosmological scalars constructed out of higher derivatives
of the scale factor. We carry out this procedure for pure dust, Chaplygin gas
and generalised Chaplygin gas energy-momentum tensors. In each case it leads to
a constraint on the scalars thus giving rise to a test of General Relativity.
We also discuss a formulation of the Friedmann equation as unparametrised
geodesic motion and its connection with the Lagrangian treatment of perfect
fluids coupled to gravity.
| arxiv topic:gr-qc astro-ph hep-th |
arxiv_dataset-713807.0307 | Two-dimensional molecular para-hydrogen and ortho-deuterium at zero
temperature
cond-mat.other
We study molecular para-hydrogen (p-${\rm H_{2}}$) and ortho-deuterium
(o-${\rm D_{2}}$) in two dimensions and in the limit of zero temperature by
means of the diffusion Monte Carlo method. We report energetic and structural
properties of both systems like the total and kinetic energy per particle,
radial pair distribution function, and Lindemann's ratio in the low pressure
regime. By comparing the total energy per particle as a function of the density
in liquid and solid p-${\rm H_{2}}$, we show that molecular para-hydrogen, and
also ortho-deuterium, remain solid at zero temperature. Interestingly, we
assess the quality of three different symmetrized trial wave functions, based
on the Nosanow-Jastrow model, in the p-${\rm H_{2}}$ solid film at the
variational level. In particular, we analyze a new type of symmetrized trial
wave function which has been used very recently to describe solid $^{4}$He and
found that also characterizes hydrogen satisfactorily. With this wave function,
we show that the one-body density matrix $\varrho_{1} (r)$ of solid p-${\rm
H_{2}}$ possesses off-diagonal long range order, with a condensate fraction
that increases sizably in the negative pressure regime.
| arxiv topic:cond-mat.other |
arxiv_dataset-714807.0407 | Turning a nickelate Fermi surface into a cuprate-like one through
heterostructuring
cond-mat.str-el cond-mat.mtrl-sci
Using the local density approximation and its combination with dynamical
mean-field theory, we show that electronic correlations induce a single-sheet,
cuprate-like Fermi surface for hole-doped 1/1 LaNiO3 /LaAlO3 heterostructures,
even though both eg orbitals contribute to it. The Ni 3d 3z^2-1 orbital plays
the role of the axial Cu 4s-like orbital in the cuprates. These two results
indicate that "orbital engineering" by means of heterostructuring should be
possible. As we also find strong antiferromagnetic correlations, the low-energy
electronic and spin excitations in nickelate heterostructures resemble those of
high-temperature cuprate superconductors.
| arxiv topic:cond-mat.str-el cond-mat.mtrl-sci |
arxiv_dataset-715807.0507 | Gate complexity using Dynamic Programming
quant-ph
The relationship between efficient quantum gate synthesis and control theory
has been a topic of interest in the quantum control literature. Motivated by
this work, we describe in the present article how the dynamic programming
technique from optimal control may be used for the optimal synthesis of quantum
circuits. We demonstrate simulation results on an example system on SU(2), to
obtain plots related to the gate complexity and sample paths for different
logic gates.
| arxiv topic:quant-ph |
arxiv_dataset-716807.0607 | Weak-Interacting Holographic QCD
hep-th hep-ph nucl-th
We propose a simple prescription for including low-energy weak-interactions
into the framework of holographic QCD, based on the standard AdS/CFT dictionary
of double-trace deformations. As our proposal enables us to calculate various
electro-weak observables involving strongly coupled QCD, it opens a new
perspective on phenomenological applications of holographic QCD. We illustrate
efficiency and usefulness of our method by performing a few exemplar
calculations; neutron beta decay, charged pion weak decay, and meson-nucleon
parity non-conserving (PNC) couplings. The idea is general enough to be
implemented in both Sakai-Sugimoto as well as Hard/Soft Wall models.
| arxiv topic:hep-th hep-ph nucl-th |
arxiv_dataset-717807.0707 | Chiral two-dimensional electron gas in a periodic magnetic field
cond-mat.str-el
We study the energy spectrum and electronic properties of two-dimensional
electron gas in a periodic magnetic field of zero average with a symmetry of
triangular lattice. We demonstrate how the structure of electron energy bands
can be changed with the variation of the field strength, so that we can start
from nearly free electron gas and then transform it continuously to a system of
essentially localized chiral electron states. We find that the electrons near
some minima of the effective potential are responsible for occurrence of
dissipationless persistent currents creating a lattice of current contours. The
topological properties of the electron energy bands are also varied with the
intensity of periodic field. We calculated the topological Chern numbers of
several lower energy bands as a function of the field. The corresponding Hall
conductivity is nonzero and, when the Fermi level lies in the gap, it is
quantized.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-718807.0807 | Shortest Paths Avoiding Forbidden Subpaths
cs.DM cs.DS
In this paper we study a variant of the shortest path problem in graphs:
given a weighted graph G and vertices s and t, and given a set X of forbidden
paths in G, find a shortest s-t path P such that no path in X is a subpath of
P. Path P is allowed to repeat vertices and edges. We call each path in X an
exception, and our desired path a shortest exception-avoiding path. We
formulate a new version of the problem where the algorithm has no a priori
knowledge of X, and finds out about an exception x in X only when a path
containing x fails. This situation arises in computing shortest paths in
optical networks. We give an algorithm that finds a shortest exception avoiding
path in time polynomial in |G| and |X|. The main idea is to run Dijkstra's
algorithm incrementally after replicating vertices when an exception is
discovered.
| arxiv topic:cs.DM cs.DS |
arxiv_dataset-719807.0907 | Generation of entangled channels for perfect teleportation channels
using multi-electron quantum dots
quant-ph
In this work we have proposed a scheme for generating $N$ qubit entangled
states which can teleport an unknown state perfectly. By switching on the
exchange interaction ($J$) between the qubits one can get the desired states
periodically. A multi electron quantum dot can be a possible realization for
generating such $N$ qubit states with high fidelity. In the limit of $N \to
\infty$, there exists a unique time $t=\frac{1}{J}\cos^{-1}(-1/8)$ where the
Hamiltonian dynamics gives the $N$ qubit state that can assist perfect
teleportation. We have also discussed the effect of the nuclear spin
environment on the fidelity of teleportation for a general $N$ qubit entangled
channel.
| arxiv topic:quant-ph |
arxiv_dataset-720807.1007 | Etale and motivic cohomology and ultraproducts of schemes
math.AG math.LO
This paper is a continuation of the authors article "Enlargements of schemes"
(Log. Anal.1 (2007), no. 1, 1-60) We mainly study the behaviour of etale
cohomology, algebraic cycles and motives under ultraproducts respectively
enlargements. The main motivation for that is to find methods to transfer
statements about etale cohomology and algebraic cycles from characteristic zero
to positive characteristic and vice versa. We give one application to the
independence of $l$ of Betti numbers in etale cohomology and applications to
the complexity of algebraic cycles.
| arxiv topic:math.AG math.LO |
arxiv_dataset-721807.1107 | Five-Branes in M-Theory and a Two-Dimensional Geometric Langlands
Duality
hep-th math.AG math.RT
A recent attempt to extend the geometric Langlands duality to affine
Kac-Moody groups, has led Braverman and Finkelberg [arXiv:0711.2083] to
conjecture a mathematical relation between the intersection cohomology of the
moduli space of G-bundles on certain singular complex surfaces, and the
integrable representations of the Langlands dual of an associated affine
G-algebra, where G is any simply-connected semisimple group. For the A-type
groups, where the conjecture has been mathematically verified to a large
extent, we show that the relation has a natural physical interpretation in
terms of six-dimensional compactifications of M-theory with coincident
five-branes wrapping certain hyperkahler four-manifolds; in particular, it can
be understood as an expected invariance in the resulting spacetime BPS spectrum
under string dualities. By replacing the singular complex surface with a smooth
multi-Taub-NUT manifold, we find agreement with a closely related result
demonstrated earlier via purely field-theoretic considerations by Witten. By
adding OM five-planes to the original analysis, we argue that an analogous
relation involving the non-simply-connected D-type groups, ought to hold as
well. This is the first example of a string-theoretic interpretation of such a
two-dimensional extension to complex surfaces of the geometric Langlands
duality for the A-D groups.
| arxiv topic:hep-th math.AG math.RT |
arxiv_dataset-722807.1207 | Antiproton collisions with molecular hydrogen
physics.atom-ph physics.chem-ph
Theoretical antiproton and proton cross sections for ionization and
excitation of hydrogen molecules as well as energy spectra of the ionized
electrons were calculated in the impact-energy range from 8 to 4000 keV. The
cross sections were computed with the close-coupling formulation of the
semi-classical impact-parameter method. The target was described using a
one-active electron model centered on the target and assuming a fixed
internuclear distance during the collision process. The dependence of the
ionization cross sections on the internuclear distance is examined. The present
cross sections are compared with experimental and theoretical data from the
literature. For impact energies E > 90 keV the obtained results for ionization
by antiproton impact are comparable to the experimental data while they
disagree for energies E < 80 keV.
| arxiv topic:physics.atom-ph physics.chem-ph |
arxiv_dataset-723807.1307 | On real moduli spaces over M-curves
math.SG math.AG
Let $F$ be a genus $g$ curve and $\sigma: F \to F$ a real structure with the
maximal possible number of fixed circles. We study the real moduli space $\N' =
\Fix (\sigma^{#})$ where $\sigma^{#}: \N \to \N$ is the induced real structure
on the moduli space $\N$ of stable holomorphic bundles of rank 2 over $F$ with
fixed non-trivial determinant. In particular, we calculate $H^* (\N',\mathbb
Z)$ in the case of $g = 2$, generalizing Thaddeus' approach to computing $H^*
(\N,\mathbb Z)$.
| arxiv topic:math.SG math.AG |
arxiv_dataset-724807.1407 | The Regular C*-algebra of an Integral Domain
math.OA
To each integral domain R with finite quotients we associate a purely
infinite simple C*-algebra in a very natural way. Its stabilization can be
identified with the crossed product of the algebra of continuous functions on
the "finite adele space" corresponding to R by the action of the ax+b-group
over the quotient field Q(R). We study the relationship to generalized
Bost-Connes systems and deduce for them a description as universal C*-algebras
with the help of our construction.
| arxiv topic:math.OA |
arxiv_dataset-725807.1507 | A Search for the Near-Infrared Counterpart to GCRT J1745-3009
astro-ph
We present an optical/near-infrared search for a counterpart to the
perplexing radio transient GCRT J1745-3009, a source located ~1 degree from the
Galactic Center. Motivated by some similarities to radio bursts from nearby
ultracool dwarfs, and by a distance upper limit of 70 pc for the emission to
not violate the 1e12 K brightness temperature limit for incoherent radiation,
we searched for a nearby star at the position of GCRT J1745-3009. We found only
a single marginal candidate, limiting the presence of any late-type star to >1
kpc (spectral types earlier than M9), >200 pc (spectral types L and T0-T4), and
>100 pc (spectral types T4-T7), thus severely restricting the possible local
counterparts to GCRT J1745-3009. We also exclude any white dwarf within 1 kpc
or a supergiant star out to the distance of the Galactic Center as possible
counterparts. This implies that GCRT J1745-3009 likely requires a coherent
emission process, although whether or not it reflects a new class of sources is
unclear.
| arxiv topic:astro-ph |
arxiv_dataset-726807.1607 | On equifocal submanifolds with non-flat section in symmetric spaces of
rank two
math.DG
In this paper, we show that there exists no equifocal submanifold with
non-flat section in four irreducible simply connected symmetric spaces of
compact type and rank two. Also, we show a fact for the sections of equifocal
submanifolds with non-flat section in other irreducible simply connected
symmetric spaces of compact type and rank two.
| arxiv topic:math.DG |
arxiv_dataset-727807.1707 | Quasi-Homogeneous Backward-Wave Plasmonic Structures: Theory and
Accurate Simulation
physics.optics physics.comp-ph
Backward waves and negative refraction are shown to exist in plasmonic
crystals whose lattice cell size is a very small fraction of the vacuum
wavelength (less than 1/40th in an illustrative example). Such
``quasi-homogeneity'' is important, in particular, for high-resolution imaging.
Real and complex Bloch bands are computed using the recently developed
finite-difference calculus of ``Flexible Local Approximation MEthods'' (FLAME)
that produces linear eigenproblems, as opposed to quadratic or nonlinear ones
typical for other techniques. FLAME dramatically improves the accuracy by
incorporating local analytical approximations of the solution into the
numerical scheme.
| arxiv topic:physics.optics physics.comp-ph |
arxiv_dataset-728807.1807 | Relevance of Abelian Symmetry and Stochasticity in Directed Sandpiles
cond-mat.stat-mech
We provide a comprehensive view on the role of Abelian symmetry and
stochasticity in the universality class of directed sandpile models, in context
of the underlying spatial correlations of metastable patterns and scars. It is
argued that the relevance of Abelian symmetry may depend on whether the dynamic
rule is stochastic or deterministic, by means of the interaction of metastable
patterns and avalanche flow. Based on the new scaling relations, we conjecture
critical exponents for avalanche, which is confirmed reasonably well in
large-scale numerical simulations.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-729807.1907 | The hyperfine energy levels of alkali metal dimers: ground-state polar
molecules in electric and magnetic fields
physics.atom-ph physics.chem-ph
We investigate the energy levels of heteronuclear alkali metal dimers in
levels correlating with the lowest rotational level of the ground electronic
state, which are important in efforts to produce ground-state ultracold
molecules. We use density-functional theory to calculate nuclear quadrupole and
magnetic coupling constants for RbK and RbCs and explore the hyperfine
structure in the presence of electric and magnetic fields. For nonrotating
states, the zero-field splittings are dominated by the electron-mediated part
of the nuclear spin-spin coupling. They are a few kHz for RbK isotopologs and a
few tens of kHz for RbCs isotopologs.
| arxiv topic:physics.atom-ph physics.chem-ph |
arxiv_dataset-730807.2007 | The NeXT Mission
astro-ph
The NeXT (New exploration X-ray Telescope), the new Japanese X-ray Astronomy
Satellite following Suzaku, is an international X-ray mission which is
currently planed for launch in 2013. NeXT is a combination of wide band X-ray
spectroscopy (3 - 80 keV) provided by multi-layer coating, focusing hard X-ray
mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray
spectroscopy (0.3 - 10 keV) provided by thin-foil X-ray optics and a
micro-calorimeter array. The mission will also carry an X-ray CCD camera as a
focal plane detector for a soft X-ray telescope and a non-focusing soft
gamma-ray detector. With these instruments, NeXT covers very wide energy range
from 0.3 keV to 600 keV. The micro-calorimeter system will be developed by
international collaboration lead by ISAS/JAXA and NASA. The simultaneous broad
bandpass, coupled with high spectral resolution of Delta E ~ 7 eV by the
micro-calorimeter will enable a wide variety of important science themes to be
pursued.
| arxiv topic:astro-ph |
arxiv_dataset-731807.2107 | Chaos synchronization of the master-slave generalized Lorenz systems via
linear state error feedback control
nlin.CD
This paper provides a unified method for analyzing chaos synchronization of
the generalized Lorenz systems. The considered synchronization scheme consists
of identical master and slave generalized Lorenz systems coupled by linear
state error variables. A sufficient synchronization criterion for a general
linear state error feedback controller is rigorously proven by means of
linearization and Lyapunov's direct methods. When a simple linear controller is
used in the scheme, some easily implemented algebraic synchronization
conditions are derived based on the upper and lower bounds of the master
chaotic system. These criteria are further optimized to improve their
sharpness. The optimized criteria are then applied to four typical generalized
Lorenz systems, i.e. the classical Lorenz system, the Chen system, the Lv
system and a unified chaotic system, obtaining precise corresponding
synchronization conditions. The advantages of the new criteria are revealed by
analytically and numerically comparing their sharpness with that of the known
criteria existing in the literature.
| arxiv topic:nlin.CD |
arxiv_dataset-732807.2207 | On Sun's conjecture concerning disjoint cosets
math.GR math.NT
In 2004, Zhi-Wei Sun posed the following conjecture: If a_1G_1,...,a_kG_k
(k>1) are finitely many pairwise disjoint left cosets in a group G with all the
indices [G:G_i] finite, then for some 1\le i<j\le k, the greatest common
divisor of [G:G_i] and [G:G_j] is at least k. In this paper, we confirm Sun's
conjecture for k=3,4.
| arxiv topic:math.GR math.NT |
arxiv_dataset-733807.2307 | Multifractal analysis of the fracture surfaces of foamed
polypropylene/polyethylene blends
cond-mat.mtrl-sci
The two-dimensional multifractal detrended fluctuation analysis is applied to
reveal the multifractal properties of the fracture surfaces of foamed
polypropylene/polyethylene blends at different temperatures. Nice power-law
scaling relationship between the detrended fluctuation function $F_{q}$ and the
scale $s$ is observed for different orders $q$ and the scaling exponent $h(q)$
is found to be a nonlinear function of $q$, confirming the presence of
multifractality in the fracture surfaces. The multifractal spectra $f(\alpha)$
are obtained numerically through Legendre transform. The shape of the
multifractal spectrum of singularities can be well captured by the width of
spectrum $\Delta\alpha$ and the difference of dimension $\Delta f$. With the
increase of the PE content, the fracture surface becomes more irregular and
complex, as is manifested by the facts that $\Delta\alpha$ increases and
$\Delta f$ decreases from positive to negative. A qualitative interpretation is
provided based on the foaming process.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-734807.2407 | First Result of Net-Charge Jet-Correlations from STAR
hep-ex
We presented results on azimuthal correlation of net-charge with high $p_T$
trigger particles. It is found that the net-charge correlation shape is similar
to that of total-charge. On the near-side, the net-charge and total-charge
$p_T$ spectra have similar shape and both are harder than the inclusives. On
the away-side, the correlated spectra are not much harder than the inclusives,
and the net-charge/total-charge ratio increases with $p_T$ and is similar to
the inclusive ratio.
| arxiv topic:hep-ex |
arxiv_dataset-735807.2507 | Regularity conditions at spatial infinity revisited
gr-qc
The regular finite initial value problem at infinity is used to obtain
regularity conditions on the freely specifiable parts of initial data for the
vacuum Einstein equations with non-vanishing second fundamental form. These
conditions ensure that the solutions of the propagation equations implied by
the conformal Einstein equations at the cylinder at spatial infinity extend
smoothly (and in fact analytically) through the critical sets where spatial
infinity touches null infinity. In order to ease the analysis the conformal
metric is assumed to be analytic, although the results presented here could be
generalised to a setting where the conformal metric is only smooth. The
analysis given here is a generalisation of the analysis on the regular finite
initial value problem first carried out by Friedrich, for initial data sets
with non-vanishing second fundamental form.
| arxiv topic:gr-qc |
arxiv_dataset-736807.2607 | Giving up the ghost
hep-th
The Pais-Uhlenbeck model is a quantum theory described by a higher-derivative
field equation. It has been believed for many years that this model possesses
ghost states (quantum states of negative norm) and therefore that this model is
a physically unacceptable quantum theory. The existence of such ghost states
was believed to be attributable to the field equation having more than two
derivatives. This paper shows that the Pais-Uhlenbeck model does not possess
any ghost states at all and that it is a perfectly acceptable quantum theory.
The supposed ghost states in this model arise if the Hamiltonian of the model
is (incorrectly) treated as being Dirac Hermitian (invariant under combined
matrix transposition and complex conjugation). However, the Hamiltonian is {\it
not} Dirac Hermitian, but rather it is PT symmetric. When it is quantized
correctly according to the rules of PT quantum mechanics, the energy spectrum
is real and bounded below and all of the quantum states have positive norm.
| arxiv topic:hep-th |
arxiv_dataset-737807.2707 | Latin trades in groups defined on planar triangulations
math.CO math.GR
For a finite triangulation of the plane with faces properly coloured white
and black, let A be the abelian group constructed by labelling the vertices
with commuting indeterminates and adding relations which say that the labels
around each white triangle add to the identity. We show that A has free rank
exactly two. Let A* be the torsion subgroup of A, and B* the corresponding
group for the black triangles. We show that A* and B* have the same order, and
conjecture that they are isomorphic.
For each spherical latin trade W, we show there is a unique disjoint mate B
such that (W,B) is a connected and separated bitrade. The bitrade (W,B) is
associated with a two-colourable planar triangulation and we show that W can be
embedded in A*, thereby proving a conjecture due to Cavenagh and Drapal. The
proof involves constructing a (0,1) presentation matrix whose permanent and
determinant agree up to sign. The Smith Normal Form of this matrix determines
A*, so there is an efficient algorithm to construct the embedding. Contrasting
with the spherical case, for each genus g>0 we construct a latin trade which is
not embeddable in any group and another that is embeddable in a cyclic group.
We construct a sequence of spherical latin trades which cannot be embedded in
any family of abelian groups whose torsion ranks are bounded. Also, we show
that any trade that can be embedded in a finitely generated abelian group can
be embedded in a finite abelian group. As a corollary, no trade can be embedded
in a free abelian group.
| arxiv topic:math.CO math.GR |
arxiv_dataset-738807.2807 | Evidence of a first-order quantum phase transition of excitons in
electron double layers
cond-mat.mes-hall
Complexity in many-particle systems occurs through processes of qualitative
differentiation. These are described by concepts such as emerging states with
specific symmetries that are linked to order parameters. In quantum Hall phases
of electrons in semiconductor double layers with large inter-layer electron
correlation there is an emergent many body exciton phase with an order
parameter that measures the condensate fraction of excitons across the
tunneling gap. As the inter-layer coupling is reduced by application of an
in-plane magnetic field, this excitonic insulating state is brought in
competition with a Fermi-metal phase of composite fermions (loosely, electrons
with two magnetic flux quanta attached) stabilized by intra-layer electron
correlation. Here we show that the quantum phase transformation between
metallic and excitonic insulating states in the coupled bilayers becomes
discontinuous (first-order) by impacts of different terms of the
electron-electron interactions that prevail on weak residual disorder. The
evidence is based on precise determinations of the excitonic order parameter by
inelastic light scattering measurements close to the phase boundary. While
there is marked softening of low-lying excitations, our experiments underpin
the roles of competing orders linked to quasi-particle correlations in removing
the divergence of quantum fluctuations.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-739807.2907 | Linearly repetitive Delone systems have a finite number of non periodic
Delone system factors
math.DS
We prove linearly repetitive Delone systems have finitely many Delone system
factors up to conjugacy. This result is also applicable to linearly repetitive
tiling systems.
| arxiv topic:math.DS |
arxiv_dataset-740807.3007 | X-Ray flares in Orion Young Stars. II. Flares, Magnetospheres, and
Protoplanetary Disks
astro-ph
We study the properties of powerful X-ray flares from 161 pre-main sequence
(PMS) stars observed with the Chandra X-ray Observatory in the Orion Nebula
region. Relationships between flare properties, protoplanetary disks and
accretion are examined in detail to test models of star-disk interactions at
the inner edge of the accretion disks. Previous studies had found no
differences in flaring between diskfree and accreting systems other than a
small overall diminution of X-ray luminosity in accreting systems. The most
important finding is that X-ray coronal extents in fast-rotating diskfree stars
can significantly exceed the Keplerian corotation radius, whereas X-ray loop
sizes in disky and accreting systems do not exceed the corotation radius. This
is consistent with models of star-disk magnetic interaction where the inner
disk truncates and confines the PMS stellar magnetosphere. We also find two
differences between flares in accreting and diskfree PMS stars. First, a
subclass of super-hot flares with peak plasma temperatures exceeding 100 MK are
preferentially present in accreting systems. Second, we tentatively find that
accreting stars produce flares with shorter durations. Both results may be
consequences of the distortion and destabilization of the stellar magnetosphere
by the interacting disk. Finally, we find no evidence that any flare types,
even slow-rise flat-top flares are produced in star-disk magnetic loops. All
are consistent with enhanced solar long-duration events with both footprints
anchored in the stellar surface.
| arxiv topic:astro-ph |
arxiv_dataset-741807.3107 | Quasiparticle spin from adiabatic transport in quantum Hall trial
wavefunctions
cond-mat.mes-hall
Quasiparticle spin (in the spacetime sense) couples to curvature of space.
Here this fact is used to calculate the spin of quasiholes in trial quantum
Hall states by adiabatically dragging them around on a sphere, for trial states
given by conformal blocks in some conformal field theory. The spin is found to
agree with the conformal weight of the corresponding field. The result
completes a recent argument that constructions using blocks from non-unitary
theories that contain negative quantum dimensions produce contradictions that
prevent them from describing topological (gapped) phases of matter.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-742807.3207 | Boundary conditions for coupled quasilinear wave equations with
application to isolated systems
gr-qc
We consider the initial-boundary value problem for systems of quasilinear
wave equations on domains of the form $[0,T] \times \Sigma$, where $\Sigma$ is
a compact manifold with smooth boundaries $\partial\Sigma$. By using an
appropriate reduction to a first order symmetric hyperbolic system with maximal
dissipative boundary conditions, well posedness of such problems is established
for a large class of boundary conditions on $\partial\Sigma$. We show that our
class of boundary conditions is sufficiently general to allow for a well posed
formulation for different wave problems in the presence of constraints and
artificial, nonreflecting boundaries, including Maxwell's equations in the
Lorentz gauge and Einstein's gravitational equations in harmonic coordinates.
Our results should also be useful for obtaining stable finite-difference
discretizations for such problems.
| arxiv topic:gr-qc |
arxiv_dataset-743807.3307 | Gravity effects in inclined air showers induced by cosmic neutrino
hep-ph astro-ph
The Randall-Sundrum model with a small curvature is considered in which
five-dimensional Planck scale lies in the TeV region, and a spectrum of
Kaluza-Klein gravitons reminds that in one flat extra dimension. The cross
sections for interactions of ultra-high energy cosmic neutrinos with nucleons
are calculated. It is shown that effects related with massive graviton
excitations can be detected in deeply penetrating inclined air showers induced
by these neutrinos. The expected number of air showers at the Auger Observatory
is estimated as a function of two parameters of the model.
| arxiv topic:hep-ph astro-ph |
arxiv_dataset-744807.3407 | Proton channels
cond-mat.soft
The structure of Nafion, the polymer electrolyte membrane used in some fuel
cells, has been extensively debated over recent decades. Now, a newly proposed
model reveals the nanoscale arrangement that could explain the excellent
transport properties of the material.
| arxiv topic:cond-mat.soft |
arxiv_dataset-745807.3507 | Multiplets Matter: The Electronic Structure of Rare-Earth Semiconductors
and Semimetals
cond-mat.str-el cond-mat.mtrl-sci
We demonstrate that a theoretical framework fully incorporating intra-atomic
correlations and multiplet structure of the localized 4f states is required in
order to capture the essential physics of rare-earth semiconductors and
semimetals. We focus in particular on the rare-earth semimetal erbium arsenide
(ErAs), for which effective one-electron approaches fail to provide a
consistent picture of both high and low-energy electronic states. We treat the
many-body states of the Er 4f shell within an atomic approximation in the
framework of dynamical mean-field theory. Our results for the magnetic-field
dependence of the 4f local moment, the influence of multiplets on the
photoemission spectrum, and the exchange splitting of the Fermi surface pockets
as measured from Shubnikov-de Haas oscillations, are found to be in good
agreement with experimental results.
| arxiv topic:cond-mat.str-el cond-mat.mtrl-sci |
arxiv_dataset-746807.3607 | Thermal inflation, baryogenesis and axions
hep-ph
In a previous paper, we proposed a simple extension of the Minimal
Supersymmetric Standard Model which gives rise to thermal inflation and
baryogenesis in a natural and remarkably consistent way. In this paper, we
consider the $\lambda_\phi = 0$ special case of our model, which is the minimal
way to incorporate a Peccei-Quinn symmetry. The axino/flatino becomes the
lightest supersymmetric particle with $m_\axino \sim 1$ to $10 \GeV$ and is
typically over-produced during the flaton decay. Interestingly though, the dark
matter abundance is minimized for $m_\axino \sim 1 \GeV$, $f_a \sim 10^{11}$ to
$10^{12} \GeV$ and $|\mu| \sim 400 \GeV$ to $2 \TeV$ at an abundance coincident
with the observed abundance and with significant amounts of both axions and
axinos. Futhermore, for these values the baryon abundance naturally matches the
observed abundance.
| arxiv topic:hep-ph |
arxiv_dataset-747807.3707 | Origin and tuning of the magnetocaloric effect for the magnetic
refrigerant MnFe(P1-xGex)
cond-mat.mtrl-sci cond-mat.str-el
Neutron diffraction and magnetization measurements of the magneto refrigerant
Mn1+yFe1-yP1-xGex reveal that the ferromagnetic and paramagnetic phases
correspond to two very distinct crystal structures, with the magnetic entropy
change as a function of magnetic field or temperature being directly controlled
by the phase fraction of this first-order transition. By tuning the physical
properties of this system we have achieved a maximum magnetic entropy change
exceeding 74 J/Kg K for both increasing and decreasing field, more than twice
the value of the previous record.
| arxiv topic:cond-mat.mtrl-sci cond-mat.str-el |
arxiv_dataset-748807.3807 | Quintom Cosmology with General Potentials
hep-th astro-ph
We investigate the phase-space structure of the quintom paradigm in the
framework of a spatially flat, open, or closed isotropic and homogeneous
universe. We examine the dynamical evolution under the assumption of late-time
dark energy domination, without specifying the explicit quintom potential form.
The obtained cosmological behavior is qualitatively different than that
acquired from the single phantom model.
| arxiv topic:hep-th astro-ph |
arxiv_dataset-749807.3907 | Nonlinear optimization for matroid intersection and extensions
math.CO math.OC
We address optimization of nonlinear functions of the form $f(Wx)$, where
$f:\R^d\to \R$ is a nonlinear function, $W$ is a $d\times n$ matrix, and
feasible $x$ are in some large finite set $F$ of integer points in $\R^n$. One
motivation is multi-objective discrete optimization, where $f$ trades off the
linear functions given by the rows of $W$. Another motivation is to extend
known results about polynomial-time linear optimization over discrete
structures to nonlinear optimization. We assume that the convex hull of $F$ is
well-described by linear inequalities. For example, the set of characteristic
vectors of common bases of a pair of matroids on a common ground set. When $F$
is well described, $f$ is convex (or even quasiconvex), and $W$ has a fixed
number of rows and is unary encoded or with entries in a fixed set, we give an
efficient deterministic algorithm for maximization. When $F$ is well described,
$f$ is a norm, and binary-encoded $W$ is nonnegative, we give an efficient
deterministic constant-approximation algorithm for maximization. When $F$ is
well described, $f$ is ``ray concave'' and non-decreasing, and $W$ has a fixed
number of rows and is unary encoded or with entries in a fixed set, we give an
efficient deterministic constant-approximation algorithm for minimization. When
$F$ is the set of characteristic vectors of common bases of a pair of vectorial
matroids on a common ground set, $f$ is arbitrary, and $W$ has a fixed number
of rows and is unary encoded, we give an efficient randomized algorithm for
optimization.
| arxiv topic:math.CO math.OC |
arxiv_dataset-750807.4007 | $p$-adic Eisenstein-Kronecker series for CM elliptic curves and the
Kronecker limit formulas
math.NT
Consider an elliptic curve defined over an imaginary quadratic field $K$ with
good reduction at the primes above $p\geq 5$ and has complex multiplication by
the full ring of integers $\mathcal{O}_K$ of $K$. In this paper, we construct
$p$-adic analogues of the Eisenstein-Kronecker series for such elliptic curve
as Coleman functions on the elliptic curve. We then prove $p$-adic analogues of
the first and second Kronecker limit formulas by using the distribution
relation of the Kronecker theta function.
| arxiv topic:math.NT |
arxiv_dataset-751807.4107 | Description of the free motion with momentums in Godel's universe
gr-qc math-ph math.MP
We study the geodesic motion in Godel's universe, using conserved quantities.
We give a necessary and sufficient condition for curves to be geodesic curves
in terms of conserved quantities, which can be computed from the initial values
of the curve. We check our result with numerical simulations too.
| arxiv topic:gr-qc math-ph math.MP |
arxiv_dataset-752807.4207 | High-energy hadron physics at J-PARC
hep-ph hep-ex nucl-ex nucl-th
The J-PARC facility is near completion and experiments will start in 2009 on
nuclear and particle physics projects. In this article, the J-PARC facility is
introduced, and possible projects are discussed in high-energy hadron physics
by using the primary proton beam of 30-50 GeV. There are proposed experiments
on charm-production and Drell-Yan processes as well as single spin asymmetries
for investigating quark and gluon structure of the nucleon and nuclei.
Parton-energy loss could be studied in the Drell-Yan processes. There is also a
proposal on hadron-mass modifications in a nuclear medium by using the proton
beam. In addition, possible topics include transition from hadron to quark
degrees of freedom by elastic pp scattering, color transparency by (p,2p),
short-range correlation in nuclear force by (p,2pN), tensor structure functions
for spin-one hadrons, fragmentation functions, and generalized parton
distributions in the ERBL region although proposals are not written on these
projects. If proton-beam polarization is attained, it is possible to
investigate details of nucleon spin structure. In the last part of this
article, our own studies are explained on parton distribution functions in
connection with the J-PARC projects.
| arxiv topic:hep-ph hep-ex nucl-ex nucl-th |
arxiv_dataset-753807.4307 | Derivation of Effective Evolution Equations from Microscopic Quantum
Dynamics
math-ph math.AP math.MP
In these lecture notes we discuss recent progress in the rigorous derivation
of effective evolution equations for the description of the dynamics of quantum
mechanical many-body systems.
| arxiv topic:math-ph math.AP math.MP |
arxiv_dataset-754807.4407 | Dynamical Casimir-Polder force between an atom and a conducting wall
quant-ph
The time-dependent Casimir-Polder force arising during the time evolution of
an initially bare two-level atom, interacting with the radiation field and
placed near a perfectly conducting wall, is considered. Initially the
electromagnetic field is supposed to be in the vacuum state and the atom in its
ground state. The analytical expression of the force as a function of time and
atom-wall distance, is evaluated from the the time-dependent atom-field
interaction energy. Physical features and limits of validity of the results are
discussed in detail.
| arxiv topic:quant-ph |
arxiv_dataset-755807.4507 | Electromagnetic effects in Kl3 decays
hep-ph
We study the radiative corrections to all Kl3 decay modes to leading
non-trivial order in the chiral effective field theory, working with a fully
inclusive prescription on real photon emission. We present new results for Kmu3
modes and update previous results on Ke3 modes. Our analysis provides important
theoretical input for the extraction of the CKM element Vus from Kl3 decays.
| arxiv topic:hep-ph |
arxiv_dataset-756807.4607 | Phase diffusion and locking in single-qubit lasers
cond-mat.mes-hall
Motivated by recent experiments, which demonstrated lasing and cooling of the
electromagnetic field in an electrical resonator coupled to a superconducting
qubit, we study the phase coherence and diffusion of the system in the lasing
state. We also discuss phase locking and synchronization induced by an
additional {\sl ac} driving of the resonator. We extend earlier work to account
for the strong qubit-resonator coupling and to include the effects of
low-frequency qubit's noise. We show that the strong coupling may lead to a
double peak structure of the spectrum, while the shape and width are determined
to the low-frequency noise.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-757807.4707 | Strangely dispersed minimal sets in the quasiperiodically forced Arnold
map
math.DS
We study quasiperiodically forced circle endomorphisms, homotopic to the
identity, and show that under suitable conditions these exhibit uncountably
many minimal sets with a complicated structure, to which we refer to as
`strangely dispersed'. Along the way, we generalise some well-known results
about circle endomorphisms to the uniquely ergodically forced case. Namely, all
rotation numbers in the rotation interval of a uniquely ergodically forced
circle endomorphism are realised on minimal sets, and if the rotation interval
has non-empty interior then the topological entropy is strictly positive. The
results apply in particular to the quasiperiodically forced Arnold circle map,
which serves as a paradigm example.
| arxiv topic:math.DS |
arxiv_dataset-758807.4807 | H2-optimal approximation of MIMO linear dynamical systems
math.OC math.DS
We consider the problem of approximating a multiple-input multiple-output
(MIMO) $p\times m$ rational transfer function $H(s)$ of high degree by another
$p\times m$ rational transfer function $\hat H(s)$ of much smaller degree, so
that the ${\cal H}_2$ norm of the approximation error is minimized. We
characterize the stationary points of the ${\cal H}_2$ norm of the
approximation error by tangential interpolation conditions and also extend
these results to the discrete-time case. We analyze whether it is reasonable to
assume that lower-order models can always be approximated arbitrarily closely
by imposing only first-order interpolation conditions. Finally, we analyze the
${\cal H}_2$ norm of the approximation error for a simple case in order to
illustrate the complexity of the minimization problem.
| arxiv topic:math.OC math.DS |
arxiv_dataset-759807.4907 | An Ore-type theorem for perfect packings in graphs
math.CO
We say that a graph G has a perfect H-packing (also called an H-factor) if
there exists a set of disjoint copies of H in G which together cover all the
vertices of G. Given a graph H, we determine, asymptotically, the Ore-type
degree condition which ensures that a graph G has a perfect H-packing. More
precisely, let \delta_{\rm Ore} (H,n) be the smallest number k such that every
graph G whose order n is divisible by |H| and with d(x)+d(y)\geq k for all
non-adjacent x \not = y \in V(G) contains a perfect H-packing. We determine
\lim_{n\to \infty} \delta_{\rm Ore} (H,n)/n.
| arxiv topic:math.CO |
arxiv_dataset-760807.5007 | Generalized Theory of Landau Damping
cond-mat.stat-mech
Collisionless damping of electrical waves in plasma is investigated in the
frame of the classical formulation of the problem. The new principle of
regularization of the singular integral is used. The exact solution of the
corresponding dispersion equation is obtained. The results of calculations lead
to existence of discrete spectrum of frequencies and discrete spectrum of
dispersion curves. Analytical results are in good coincidence with results of
direct mathematical experiments. Key words: Foundations of the theory of
transport processes and statistical physics; Boltzmann physical kinetics;
damping of plasma waves, linear theory of wave`s propagation PACS: 67.55.Fa,
67.55.Hc
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-761807.5107 | Stability properties for some non-autonomous dissipative phenomena
proved by families of Liapunov functionals
math-ph math.MP
We prove some new results regarding the boundedness, stability and
attractivity of the solutions of a class of initial-boundary-value problems
characterized by a quasi-linear third order equation which may contain
time-dependent coefficients. The class includes equations arising in
Superconductor Theory, and in the Theory of Viscoelastic Materials. In the
proof we use a family of Liapunov functionals W depending on two parameters,
which we adapt to the `error', i.e. to the size of the chosen neighbourhood of
the null solution.
| arxiv topic:math-ph math.MP |
arxiv_dataset-762808.0068 | Interstellar Chemistry: Radiation, Dust and Metals
astro-ph
An overview is given of the chemical processes that occur in primordial
systems under the influence of radiation, metal abundances and dust surface
reactions. It is found that radiative feedback effects differ for UV and X-ray
photons at any metallicity, with molecules surviving quite well under
irradiation by X-rays. Starburst and AGN will therefore enjoy quite different
cooling abilities for their dense molecular gas. The presence of a cool
molecular phase is strongly dependent on metallicity. Strong irradiation by
cosmic rays (>100x the Milky Way value) forces a large fraction of the CO gas
into neutral carbon. Dust is important for H2 and HD formation, already at
metallicities of 10^-4-10^-3 solar, for electron abundances below 10^-3.
| arxiv topic:astro-ph |
arxiv_dataset-763808.0168 | Topological D-branes from Descent
hep-th
Witten couples the open topological B-model to a holomorphic vector bundle by
adding to the boundary of the worldsheet a Wilson loop for an integrable
connection on the bundle. Using the descent procedure for boundary vertex
operators in this context, I generalize this construction to write a worldsheet
coupling for a graded vector bundle with an integrable superconnection. I then
compute the open string vertex operators between two such boundaries. A theorem
of J. Block gives that this is equivalent to coupling the B-model to an
arbitrary object in the derived category.
| arxiv topic:hep-th |
arxiv_dataset-764808.0268 | Simulations of the Sunyaev-Zeldovich Effect from Quasars
astro-ph
Quasar feedback has most likely a substantial but only partially understood
impact on the formation of structure in the universe. A potential direct probe
of this feedback mechanism is the Sunyaev-Zeldovich effect: energy emitted from
quasar heats the surrounding intergalactic medium and induce a distortion in
the microwave background radiation passing through the region. Here we examine
the formation of such hot quasar bubbles using a cosmological hydrodynamic
simulation which includes a self-consistent treatment of black hole growth and
associated feedback, along with radiative gas cooling and star formation. From
this simulation, we construct microwave maps of the resulting Sunyaev-Zeldovich
effect around black holes with a range of masses and redshifts. The size of the
temperature distortion scales approximately with black hole mass and accretion
rate, with a typical amplitude up to a few micro-Kelvin on angular scales
around 10 arcseconds. We discuss prospects for the direct detection of this
signal with current and future single-dish and interferometric observations,
including ALMA and CCAT. These measurements will be challenging, but will allow
us to characterize the evolution and growth of supermassive black holes and the
role of their energy feedback on galaxy formation.
| arxiv topic:astro-ph |
arxiv_dataset-765808.0368 | Global regularity of wave maps V. Large data local wellposedness and
perturbation theory in the energy class
math.AP
Using the harmonic map heat flow and the function spaces of Tataru and the
author, we establish a large data local well-posedness result in the energy
class for wave maps from two-dimensional Minkowski space $\R^{1+2}$ to
hyperbolic spaces $\H^m$. This is one of the five claims required in an earlier
paper in this series to prove global regularity for such wave maps.
| arxiv topic:math.AP |
arxiv_dataset-766808.0468 | On a correspondence between regular and non-regular operator monotone
functions
math-ph math.MP math.OA
We prove that there is a bijection between the families of regular and
non-regular operator monotone functions. As an application we give a new proof
of the operator monotonicity of a certain class of functions related to
Wigner-Yanase-Dyson skew information.
| arxiv topic:math-ph math.MP math.OA |
arxiv_dataset-767808.0568 | Idealized glass transitions under pressure: dynamics versus
thermodynamics
cond-mat.mtrl-sci
The interplay of slow dynamics and thermodynamic features of dense liquids is
studied by examinining how the glass transition changes depending on the
presence or absence of Lennard-Jones-like attractions. Quite different
thermodynamic behavior leaves the dynamics unchanged, with important
consequences for high-pressure experiments on glassy liquids. Numerical results
are obtained within mode-coupling theory (MCT), but the qualitative features
are argued to hold more generally. A simple square-well model can be used to
explain generic features found in experiment.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-768808.0668 | Dynamics of non-harmonic internal gravity wave packets in stratified
media
physics.flu-dyn physics.ao-ph
In the paper taking the assumption of the slowness of the change of the
parameters of the vertically stratified medium in the horizontal direction and
in time, the evolution of the non-harmonic wave packages of the internal
gravity waves has been analyzed. The concrete form of the wave packages can be
expressed through some model functions and is defined by the local behavior of
the dispersive curves of the separate modes near to the corresponding special
points. The solution of this problem is possible with the help of the modified
variant of the special-time ray method offered by the authors (the method of
geometrical optics), the basic difference of which consists that the asymptotic
representation of the solution may be found in the form the series of the
non-integer degrees of some small parameter. At that the exponent depends on
the concrete form of representation of this package. The obvious kind of the
representation is determined from the principle of the localness and the
asymptotic behavior of the solution in the stationary and the
horizontally-homogeneous case. The phases of the wave packages are determined
from the corresponding equations of the eikonal, which can be solved
numerically on the characteristics (rays). Amplitudes of the wave packages are
determined from the laws of conservation of the some invariants along the
characteristics (rays).
| arxiv topic:physics.flu-dyn physics.ao-ph |
arxiv_dataset-769808.0768 | Foundations of Information Theory
cs.IT math.IT
Information is the basic concept of information theory. However, there is no
definition of this concept that can encompass all uses of the term information
in information theories and beyond. Many question a possibility of such a
definition. However, foundations of information theory developed in the context
of the general theory of information made it possible to build such a relevant
and at the same time, encompassing definition. Foundations of information
theory are built in a form of ontological principles, which reflect basic
features of information and information processes.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-770808.0868 | Corrigendum and addendum to: Linearly recurrent subshifts have a finite
number of non-periodic factors
math.DS
We prove that a subshift $(X,T)$ is linearly recurrent if and only if it is a
primitive and proper $S$-adic subshift. This corrects Proposition 6 in F.
Durand ({\it Ergod. Th. & Dynam. Sys. {\bf 20}} (2000), 1061--1078).
| arxiv topic:math.DS |
arxiv_dataset-771808.0968 | On the complete integrability and linearization of nonlinear ordinary
differential equations - Part IV: Coupled second order equations
nlin.SI
Coupled second order nonlinear differential equations are of fundamental
importance in dynamics. In this part of our study on the integrability and
linearization of nonlinear ordinary differential equations we focus our
attention on the method of deriving general solution of two coupled second
order nonlinear ordinary differential equations through the extended
Prelle-Singer procedure. We describe a procedure to obtain integrating factors
and required number of integrals of motion so that the general solution follows
straightforwardly from these integrals. Our method tackles both isotropic and
non-isotropic cases in a systematic way. In addition to the above, we introduce
a new method of transforming coupled second order nonlinear ODEs into uncoupled
ones. We illustrate the theory with potentially important examples.
| arxiv topic:nlin.SI |
arxiv_dataset-772808.1068 | Symplectic approach to quantum constraints
quant-ph
A general prescription for the treatment of constrained quantum motion is
outlined. We consider in particular constraints defined by algebraic
submanifolds of the quantum state space. The resulting formalism is applied to
obtain solutions to the constrained dynamics of systems of multiple spin-1/2
particles. When the motion is constrained to a certain product space containing
all of the energy eigenstates, the dynamics thus obtained are quasi-unitary in
the sense that the equations of motion take a form identical to that of unitary
motion, but with different boundary conditions. When the constrained subspace
is a product space of disentangled states, the associated motion is more
intricate. Nevertheless, the equations of motion satisfied by the dynamical
variables are obtained in closed form.
| arxiv topic:quant-ph |
arxiv_dataset-773808.1168 | Curvaton Dynamics and the Non-Linearity Parameters in Curvaton Model
hep-th astro-ph gr-qc hep-ph
We investigate the curvaton dynamics and the non-linearity parameters in
curvaton model with potential slightly deviating from the quadratic form in
detail. The non-linearity parameter $g_{NL}$ will show up due to the curvaton
self-interaction. We also point out that the leading order of non-quadratic
term in the curvaton potential can be negative, for example in the axion-type
curvaton model. If a large positive $g_{NL}$ is detected, the axion-type
curvaton model will be preferred.
| arxiv topic:hep-th astro-ph gr-qc hep-ph |
arxiv_dataset-774808.1268 | Interface solitons in two-dimensional photonic lattices
nlin.PS
We analyze localization of light at the interface separating square and
hexagonal photonic lattices, as recently realized experimentally in
two-dimensional laser-written waveguide arrays in silica glass with
self-focusing nonlinearity [A. Szameit {\em et al.}, Opt. Lett. {\bf 33}, 663
(2008)]. We reveal the conditions for the existence of {\em linear} and {\em
nonlinear} surface states substantially influenced by the lattice topology, and
study the effect of the different symmetries and couplings on the stability of
two-dimensional interface solitons.
| arxiv topic:nlin.PS |
arxiv_dataset-775808.1368 | On some deterministic dictionaries supporting sparsity
cs.IT math.IT
We describe a new construction of an incoherent dictionary, referred to as
the oscillator dictionary, which is based on considerations in the
representation theory of finite groups. The oscillator dictionary consists of
order of p^5 unit vectors in a Hilbert space of dimension p, where p is an odd
prime, whose pairwise inner products have magnitude of at most 4/sqrt(p). An
explicit algorithm to construct a large portion of the oscillator dictionary is
presented.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-776808.1468 | Monitoring of band gap and magnetic state of graphene nanoribbons
through vacancies
cond-mat.mes-hall
Using first-principles plane wave calculations we predict that electronic and
magnetic properties of graphene nanoribbons can be affected by defect-induced
itinerant states. The band gaps of armchair nanoribbons can be modified by
hydrogen saturated holes. Defects due to periodically repeating vacancy or
divacancies induce metallization, as well as magnetization in non-magnetic
semiconducting nanoribbons due to the spin-polarization of local defect states.
Antiferromagnetic ground state of semiconducting zigzag ribbons can change to
ferrimagnetic state upon creation of vacancy defects, which reconstruct and
interact with edge states. Even more remarkable is that all these effects of
vacancy defects are found to depend on their geometry and position relative to
edges. It is shown that these effects can, in fact, be realized without really
creating defects.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-777808.1568 | Spacings and pair correlations for finite Bernoulli convolutions
math.NT math.DS
We consider finite Bernoulli convolutions with a parameter $1/2 < r < 1$
supported on a discrete point set, generically of size $2^N$. These sequences
are uniformly distributed with respect to the infinite Bernoulli convolution
measure $\nu_r$, as $N$ tends to infinity. Numerical evidence suggests that for
a generic $r$, the distribution of spacings between appropriately rescaled
points is Poissonian. We obtain some partial results in this direction; for
instance, we show that, on average, the pair correlations do not exhibit
attraction or repulsion in the limit. On the other hand, for certain algebraic
$r$ the behavior is totally different.
| arxiv topic:math.NT math.DS |
arxiv_dataset-778808.1668 | Reliability of P mode event classification using contemporaneous BiSON
and GOLF observations
astro-ph
We carried out a comparison of the signals seen in contemporaneous BiSON and
GOLF data sets. Both instruments perform Doppler shift velocity measurements in
integrated sunlight, although BiSON perform measurements from the two wings of
potassium absorption line and GOLF from one wing of the NaD1 line.
Discrepancies between the two datasets have been observed. We show,in fact,
that the relative power depends on the wing in which GOLF data observes. During
the blue wing period, the relative power is much higher than in BiSON datasets,
while a good agreement has been observed during the red period.
| arxiv topic:astro-ph |
arxiv_dataset-779808.1768 | Quadratic fermionic interactions yield effective Hamiltonians for
adiabatic quantum computing
quant-ph
Polynomially-large ground-state energy gaps are rare in many-body quantum
systems, but useful for adiabatic quantum computing. We show analytically that
the gap is generically polynomially-large for quadratic fermionic Hamiltonians.
We then prove that adiabatic quantum computing can realize the ground states of
Hamiltonians with certain random interactions, as well as the ground states of
one, two, and three-dimensional fermionic interaction lattices, in polynomial
time. Finally, we use the Jordan-Wigner transformation and a related
transformation for spin-3/2 particles to show that our results can be restated
using spin operators in a surprisingly simple manner. A direct consequence is
that the one-dimensional cluster state can be found in polynomial time using
adiabatic quantum computing.
| arxiv topic:quant-ph |
arxiv_dataset-780808.1868 | Scaling exponents of Forced Polymer Translocation through a nano-pore
cond-mat.soft
We investigate several scaling properties of a translocating homopolymer
through a thin pore driven by an external field present inside the pore only
using Langevin Dynamics (LD) simulation in three dimension (3D). Specifically
motivated by several recent theoretical and numerical studies that are
apparently at odds with each other, we determine the chain length dependence of
the scaling exponents of the average translocation time, the average velocity
of the center of mass, $<v_{CM}>$, the effective radius of gyration during the
translocation process, and the scaling exponent of the translocation coordinate
($s$-coordinate) as a function of the translocation time. We further discuss
the possibility that in the case of driven translocation the finite pore size
and its geometry could be responsible that the veclocity scaling exponent is
less than unity and discuss the dependence of the scaling exponents on the pore
geometry for the range of $N$ studied here.
| arxiv topic:cond-mat.soft |
arxiv_dataset-781808.1968 | LSD and AMAZE: the mass-metallicity relation at z>3
astro-ph
We present the first results on galaxy metallicity evolution at z>3 from two
projects, LSD (Lyman-break galaxies Stellar populations and Dynamics) and AMAZE
(Assessing the Mass Abundance redshift Evolution). These projects use deep
near-infrared spectroscopic observations of a sample of ~40 LBGs to estimate
the gas-phase metallicity from the emission lines. We derive the
mass-metallicity relation at z$>$3 and compare it with the same relation at
lower redshift. Strong evolution from z=0 and z=2 to z=3 is observed, and this
finding puts strong constrains on the models of galaxy evolution. These
preliminary results show that the effective oxygen yields does not increase
with stellar mass, implying that the simple outflow model does not apply at
z>3.
| arxiv topic:astro-ph |
arxiv_dataset-782808.2068 | Explicit form of the Mann-Marolf surface term in (3+1) dimensions
gr-qc hep-th
The Mann-Marolf surface term is a specific candidate for the "reference
background term" that is to be subtracted from the Gibbons-Hawking surface term
in order make the total gravitational action of asymptotically flat spacetimes
finite. That is, the total gravitational action is taken to be:
(Einstein-Hilbert bulk term) + (Gibbons-Hawking surface term) - (Mann-Marolf
surface term).
As presented by Mann and Marolf, their surface term is specified implicitly
in terms of the Ricci tensor of the boundary. Herein I demonstrate that for the
physically interesting case of a (3+1) dimensional bulk spacetime, the
Mann-Marolf surface term can be specified explicitly in terms of the Einstein
tensor of the (2+1) dimensional boundary.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-783808.2168 | Interstellar Weather Vanes: GLIMPSE Mid-Infrared Stellar-Wind Bowshocks
in M17 and RCW49
astro-ph
We report the discovery of six infrared stellar-wind bowshocks in the
Galactic massive star formation regions M17 and RCW49 from Spitzer GLIMPSE
(Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) images. The InfraRed
Array Camera (IRAC) on the Spitzer Space Telescope clearly resolves the
arc-shaped emission produced by the bowshocks. We combine Two Micron All-Sky
Survey (2MASS), Spitzer, MSX, and IRAS observations to obtain the spectral
energy distributions (SEDs) of the bowshocks and their individual driving
stars. We use the stellar SEDs to estimate the spectral types of the three
newly-identified O stars in RCW49 and one previously undiscovered O star in
M17. One of the bowshocks in RCW49 reveals the presence of a large-scale flow
of gas escaping the H II region at a few 10^2 km/s. Radiation-transfer modeling
of the steep rise in the SED of this bowshock toward longer mid-infrared
wavelengths indicates that the emission is coming principally from dust heated
by the star driving the shock. The other 5 bowshocks occur where the stellar
winds of O stars sweep up dust in the expanding H II regions.
| arxiv topic:astro-ph |
arxiv_dataset-784808.2268 | On the geometry of a class of invariant measures and a problem of Aldous
math.PR math.CO
In his 1985 survey of notions of exchangeability, Aldous introduced a form of
exchangeability corresponding to the symmetries of the infinite discrete cube,
and asked whether these exchangeable probability measures enjoy a
representation theorem similar to those for exchangeable sequences, arrays and
set-indexed families. In this note we to prove that, whereas the known
representation theorems for different classes of partially exchangeable
probability measure imply that the compact convex set of such measures is a
Bauer simplex (that is, its subset of extreme points is closed), in the case of
cube-exchangeability it is a copy of the Poulsen simplex (in which the extreme
points are dense). This follows from the arguments used by Glasner and Weiss'
for their characterization of property (T) in terms of the geometry of the
simplex of invariant measures for associated generalized Bernoulli actions.
The emergence of this Poulsen simplex suggests that, if a representation
theorem for these processes is available at all, it must take a very different
form from the case of set-indexed exchangeable families.
| arxiv topic:math.PR math.CO |
arxiv_dataset-785808.2368 | Strong Spectral Gaps for Compact Quotients of Products of $\PSL(2,\bbR)$
math.NT
The existence of a strong spectral gap for quotients $\Gamma\bs G$ of
noncompact connected semisimple Lie groups is crucial in many applications. For
congruence lattices there are uniform and very good bounds for the spectral gap
coming from the known bounds towards the Ramanujan-Selberg Conjectures. If $G$
has no compact factors then for general lattices a strong spectral gap can
still be established, however, there is no uniformity and no effective bounds
are known. This note is concerned with the strong spectral gap for an
irreducible co-compact lattice $\Gamma$ in $G=\PSL(2,\bbR)^d$ for $d\geq 2$
which is the simplest and most basic case where the congruence subgroup
property is not known. The method used here gives effective bounds for the
spectral gap in this setting.
| arxiv topic:math.NT |
arxiv_dataset-786808.2468 | Distinguishing seesaw models at LHC with multi-lepton signals
hep-ph
We investigate the LHC discovery potential for electroweak scale heavy
neutrino singlets (seesaw I), scalar triplets (seesaw II) and fermion triplets
(seesaw III). For seesaw I we consider a heavy Majorana neutrino coupling to
the electron or muon. For seesaw II we concentrate on the likely scenario where
the new scalars decay to two leptons. For seesaw III we restrict ourselves to
heavy Majorana fermion triplets decaying to light leptons plus gauge or Higgs
bosons, which are dominant except for unnaturally small mixings. The possible
signals are classified in terms of the charged lepton multiplicity, studying
nine different final states ranging from one to six charged leptons. Using a
fast detector simulation of signals and backgrounds, it is found that the
trilepton channel l+- l+- l-+ is by far the best one for scalar triplet
discovery, and for fermion triplets it is as good as the like-sign dilepton
channel l+- l+-. For heavy neutrinos with a mass O(100) GeV, this trilepton
channel is also better than the usually studied like-sign dilepton mode. In
addition to evaluating the discovery potential, we make special emphasis on the
discrimination among seesaw models if a positive signal is observed. This could
be accomplished not only by searching for signals in different final states,
but also by reconstructing the mass and determining the charge of the new
resonances, which is possible in several cases. For high luminosities, further
evidence is provided by the analysis of the production angular distributions in
the cleanest channels with three or four leptons.
| arxiv topic:hep-ph |
arxiv_dataset-787808.2568 | Study of Systematic Uncertainties of Single Top Production at ATLAS
hep-ex hep-ph
Sytematic uncertainties to the single top production cross section
measurement at the ATLAS experiment has been studied. Different sources of
systematic uncertainties such as detector luminosity, jet energy calibration,
SM background normalization, PDF parameterization and others have been
considered. Large scale Monte-Carlo events simulation has been performed to
estimate the contribution of each source in the overall uncertainty. The study
was done for cut based analysis as well as for multivariate analysis of the
single top measurements in ATLAS. The total systematic uncertainties of the
single top cross-section measurements in its three production channels have
been estimated at 1 $\mathrm{fb}^{-1}$ and 10 $\mathrm{fb}^{-1}$ integrated
luminosity of the LHC.
| arxiv topic:hep-ex hep-ph |
arxiv_dataset-788808.2668 | Secure Neighbor Discovery in Wireless Networks: Formal Investigation of
Possibility
cs.CR cs.NI
Wireless communication enables a broad spectrum of applications, ranging from
commodity to tactical systems. Neighbor discovery (ND), that is, determining
which devices are within direct radio communication, is a building block of
network protocols and applications, and its vulnerability can severely
compromise their functionalities. A number of proposals to secure ND have been
published, but none have analyzed the problem formally. In this paper, we
contribute such an analysis: We build a formal model capturing salient
characteristics of wireless systems, most notably obstacles and interference,
and we provide a specification of a basic variant of the ND problem. Then, we
derive an impossibility result for a general class of protocols we term
"time-based protocols," to which many of the schemes in the literature belong.
We also identify the conditions under which the impossibility result is lifted.
Moreover, we explore a second class of protocols we term "time- and
location-based protocols," and prove they can secure ND.
| arxiv topic:cs.CR cs.NI |
arxiv_dataset-789808.2768 | Conditions for the spin-spiral state in itinerant magnets
cond-mat.mtrl-sci
The spin-spiral (SS) type of magnetization is studied with the Hubbard model.
Consideration of noncollinearity of the magnetic moments results in a phase
diagram which consists of regions of the SS and paramagnetic states depending
on the number of electrons and the parameter U/t (U is the Hubbard repulsion,
and t is an overlap integral). A possibility of stabilization of the SS state
with three nonzero components of magnetic moment is considered.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-790808.2868 | Measurement of the solar 8B neutrino rate with a liquid scintillator
target and 3 MeV energy threshold in the Borexino detector
astro-ph hep-ex nucl-ex
We report the measurement of electron neutrino elastic scattering from 8B
solar neutrinos with 3 MeV energy threshold by the Borexino detector in Gran
Sasso (Italy). The rate of solar neutrino-induced electron scattering events
above this energy in Borexino is 0.217 +- 0.038 (stat) +- 0.008 (syst) cpd/100
t, which corresponds to the equivalent unoscillated flux of (2.4 +- 0.4 (stat)
+- 0.1 (syst))x10^6 cm^-2 s^-1, in good agreement with measurements from SNO
and SuperKamiokaNDE. Assuming the 8B neutrino flux predicted by the high
metallicity Standard Solar Model, the average 8B neutrino survival probability
above 3 MeV is measured to be 0.29+-0.10. The survival probabilities for 7Be
and 8B neutrinos as measured by Borexino differ by 1.9 sigma. These results are
consistent with the prediction of the MSW-LMA solution of a transition in the
solar electron neutrino survival probability between the low energy
vacuum-driven and the high-energy matter-enhanced solar neutrino oscillation
regimes.
| arxiv topic:astro-ph hep-ex nucl-ex |
arxiv_dataset-791808.2968 | On the Hersch-Payne-Schiffer inequalities for Steklov eigenvalues
math.SP math.DG
We prove that the isoperimetric inequality due to Hersch-Payne-Schiffer for
the n-th nonzero Steklov eigenvalue of a bounded simply-connected planar domain
is sharp for all n=1,2,... The equality is attained in the limit by a sequence
of simply-connected domains degenerating to the disjoint union of n identical
disks. We give a new proof of this inequality for n=2 and show that it is
strict in this case. Related results are also obtained for the product of two
consecutive Steklov eigenvalues.
| arxiv topic:math.SP math.DG |
arxiv_dataset-792808.3068 | Quantifying and containing the curse of high resolution coronal imaging
astro-ph
Future missions such as Solar Orbiter (SO), InterHelioprobe, or Solar Probe
aim at approaching the Sun closer than ever before, with on board some high
resolution imagers (HRI) having a subsecond cadence and a pixel area of about
$(80km)^2$ at the Sun during perihelion. In order to guarantee their scientific
success, it is necessary to evaluate if the photon counts available at these
resolution and cadence will provide a sufficient signal-to-noise ratio (SNR).
We perform a first step in this direction by analyzing and characterizing the
spatial intermittency of Quiet Sun images thanks to a multifractal analysis.
We identify the parameters that specify the scale-invariance behavior. This
identification allows next to select a family of multifractal processes, namely
the Compound Poisson Cascades, that can synthesize artificial images having
some of the scale-invariance properties observed on the recorded images.
The prevalence of self-similarity in Quiet Sun coronal images makes it
relevant to study the ratio between the SNR present at SoHO/EIT images and in
coarsened images. SoHO/EIT images thus play the role of 'high resolution'
images, whereas the 'low-resolution' coarsened images are rebinned so as to
simulate a smaller angular resolution and/or a larger distance to the Sun. For
a fixed difference in angular resolution and in Spacecraft-Sun distance, we
determine the proportion of pixels having a SNR preserved at high resolution
given a particular increase in effective area. If scale-invariance continues to
prevail at smaller scales, the conclusion reached with SoHO/EIT images can be
transposed to the situation where the resolution is increased from SoHO/EIT to
SO/HRI resolution at perihelion.
| arxiv topic:astro-ph |
arxiv_dataset-793808.3168 | Width of exotics from QCD sum rules : tetraquarks or molecules?
hep-ph
We investigate the widths of the recently observed charmonium like resonances
X(3872), Z(4430) and Z_2(4250) using QCD sum rules. Extending previous analyses
regarding these states as diquark-antiquark states or molecules of D mesons, we
introduce the Breit-Wigner function in the pole term. We find that introducing
the width increases the mass at small Borel window region. Using the OPE up to
dimension eight, we find that the sum rules based on interpolating current with
molecular components give a stable Borel curve from which both the masses and
widths of these resonances can be well obtained. Thus the QCD sum rule approach
strongly favors the molecular description of these states.
| arxiv topic:hep-ph |
arxiv_dataset-794808.3268 | Minimal Energy Transfer of Solid Material Between Planetary Systems
astro-ph
The exchange of meteorites among the terrestrial planets of our Solar System
is a well established phenomenon that has triggered discussion of
lithopanspermia within the Solar System. Similarly, could solid material be
transferred across planetary systems? To address this question, we explore the
dynamics of the transfer of small bodies between planetary systems. In
particular, we examine a dynamical process that yields very low escape
velocities using nearly parabolic trajectories, and the reverse process that
allows for low velocity capture. These processes are chaotic and provide a
mechanism for minimal energy transfer that yield an increased transfer
probability compared to that of previously studied mechanisms that have invoked
hyperbolic trajectories. We estimate the transfer probability in a stellar
cluster as a function of stellar mass and cluster size. We find that
significant amounts of solid material could potentially have been transferred
from the early Solar System to our nearest neighbor stars. While this low
velocity mechanism improves the odds for interstellar lithopanspermia, the
exchange of biologically active materials across stellar systems depends
greatly upon the highly uncertain viability of organisms over the timescales
for transfer, typically millions of years.
| arxiv topic:astro-ph |
arxiv_dataset-795808.3368 | Numerical evaluation of the Casimir interaction between cylinders
hep-th quant-ph
We numerically evaluate the Casimir interaction energy for configurations
involving two perfectly conducting eccentric cylinders and a cylinder in front
of a plane. We consider in detail several special cases. For quasi-concentric
cylinders, we analyze the convergence of a perturbative evaluation based on
sparse matrices. For concentric cylinders, we obtain analytically the
corrections to the proximity force approximation up to second order, and we
present an improved numerical procedure to evaluate the interaction energy at
very small distances. Finally, we consider the configuration of a cylinder in
front of a plane. We first show numerically that, in the appropriate limit, the
Casimir energy for this configuration can be obtained from that of two
eccentric cylinders. Then we compute the interaction energy at small distances,
and compare the numerical results with the analytic predictions for the first
order corrections to the proximity force approximation.
| arxiv topic:hep-th quant-ph |
arxiv_dataset-796808.3468 | Stable three-dimensional spatially modulated vortex solitons in
Bose-Einstein condensates
nlin.PS
We present exact numerical solutions in the form of spatially localized
three-dimensional (3D) nonrotating and rotating (azimuthon) multipole solitons
in the Bose-Einstein condensate (BEC) confined by a parabolic trap. We
numerically show that the 3D azimuthon solutions exist as a continuous family
parametrized by the angular velocity (or, equivalently, the modulational
depth). By a linear stability analysis we show that 3D azimuthons with a
sufficiently large phase modulational depth can be stable. The results are
confirmed by direct numerical simulations of the Gross-Pitaevskii equation.
| arxiv topic:nlin.PS |
arxiv_dataset-797808.3568 | NB BLG model in N=8 superfields
hep-th
We develop the N=8 superfield description of the Bagger-Lambert-Gustavsson
(BLG) model in its Nambu bracket (NB) realization.
The basic ingredient is the octet of scalar d=3 N=8 superfields depending
also on the coordinates of a compact three dimensional space M. It is
restricted by the 'superembedding-like' equation, which can be treated as
covariantization of the linearized superembedding equation for supermembrane
(M2-brane) with respect volume preserving diffeomorphisms SDiff3 of M. The
curvatures of SDiff3 connection are expressed through the scalar superfields by
the N=8 superfield generalization of the Chern-Simons equation (super-CS
equation). We show how the dynamical BLG equations appear when studying
consistency of these basic equations.
| arxiv topic:hep-th |
arxiv_dataset-798808.3668 | The FIRST-2MASS Red Quasar Survey II: An anomalously high fraction of
LoBALs in searches for dust-reddened quasars
astro-ph
We present results on a survey to find extremely dust-reddened Type-1
Quasars. Combining the FIRST radio survey, the 2MASS Infrared Survey and the
Sloan Digital Sky Survey, we have selected a candidate list of 122 potential
red quasars. With more than 80% spectroscopically identified objects, well over
50% are classified as dust-reddened Type 1 quasars, whose reddenings (E(B-V))
range from approximately 0.1 to 1.5 magnitudes. They lie well off the color
selection windows usually used to detect quasars and many fall within the
stellar locus, which would have made it impossible to find these objects with
traditional color selection techniques. The reddenings found are much more
consistent with obscuration happening in the host galaxy rather than stemming
from the dust torus. We find an unusually high fraction of Broad Absorption
Line (BAL) quasars at high redshift, all but one of them belonging to the Low
Ionization BAL (LoBAL) class and many also showing absorption the metastable
FeII line (FeLoBAL). The discovery of further examples of dust-reddened LoBAL
quasars provides more support for the hypothesis that BAL quasars (at least
LoBAL quasars) represent an early stage in the lifetime of the quasar. The fact
that we see such a high fraction of BALs could indicate that the quasar is in a
young phase in which quasar feedback from the BAL winds is suppressing star
formation in the host galaxy.
| arxiv topic:astro-ph |
arxiv_dataset-799808.3768 | Toric Calabi-Yau four-folds dual to Chern-Simons-matter theories
hep-th
We propose a new method to find gravity duals to a large class of
three-dimensional Chern-Simons-matter theories, using techniques from dimer
models. The gravity dual is given by M-theory on AdS_4\times Y_7, where Y_7 is
an arbitrary seven-dimensional toric Sasaki-Einstein manifold. The cone of Y_7
is a toric Calabi-Yau 4-fold, which coincides with a branch of the vacuum
moduli space of Chern-Simons-matter theories.
| arxiv topic:hep-th |
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