4,112 research outputs found
Neighbours of Einstein's Equations: Connections and Curvatures
Once the action for Einstein's equations is rewritten as a functional of an
SO(3,C) connection and a conformal factor of the metric, it admits a family of
``neighbours'' having the same number of degrees of freedom and a precisely
defined metric tensor. This paper analyzes the relation between the Riemann
tensor of that metric and the curvature tensor of the SO(3) connection. The
relation is in general very complicated. The Einstein case is distinguished by
the fact that two natural SO(3) metrics on the GL(3) fibers coincide. In the
general case the theory is bimetric on the fibers.Comment: 16 pages, LaTe
Dipolar particles in a double-trap confinement: Response to tilting the dipolar orientation
We analyze the microscopic few-body properties of dipolar particles confined
in two parallel quasi-one-dimensional harmonic traps. In particular, we show
that an adiabatic rotation of the dipole orientation about the trap axes can
drive an initially non-localized few-fermion state into a localized state with
strong inter-trap pairing. For an instant, non-adiabatic rotation, however,
localization is inhibited and a highly excited state is reached. This state may
be interpreted as the few-body analog of a super-Tonks-Girardeau state, known
from one-dimensional systems with contact interactions
Manifest Duality in Born-Infeld Theory
Born-Infeld theory is formulated using an infinite set of gauge fields, along
the lines of McClain, Wu and Yu. In this formulation electromagnetic duality is
generated by a fully local functional. The resulting consistency problems are
analyzed and the formulation is shown to be consistent.Comment: 15 pages, Late
Truncations of Random Orthogonal Matrices
Statistical properties of non--symmetric real random matrices of size ,
obtained as truncations of random orthogonal matrices are
investigated. We derive an exact formula for the density of eigenvalues which
consists of two components: finite fraction of eigenvalues are real, while the
remaining part of the spectrum is located inside the unit disk symmetrically
with respect to the real axis. In the case of strong non--orthogonality,
const, the behavior typical to real Ginibre ensemble is found. In the
case with fixed , a universal distribution of resonance widths is
recovered.Comment: 4 pages, final revised version (one reference added, minor changes in
Introduction
Convex politopes and quantum separability
We advance a novel perspective of the entanglement issue that appeals to the
Schlienz-Mahler measure [Phys. Rev. A 52, 4396 (1995)]. Related to it, we
propose an criterium based on the consideration of convex subsets of quantum
states. This criterium generalizes a property of product states to convex
subsets (of the set of quantum-states) that is able to uncover a new
geometrical property of the separability property
The Charm Content of W+1 Jet Events as a Probe of the Strange Quark Distribution Function
We investigate the prospects for measuring the strange quark distribution
function of the proton in associated plus charm quark production at the
Tevatron. The quark signal produced by strange quark -- gluon fusion,
and , is approximately 5\%
of the inclusive jet cross section for jets with a transverse momentum
~GeV. We study the sensitivity of the plus charm quark cross
section to the parametrization of the strange quark distribution function, and
evaluate the various background processes. Strategies to identify charm quarks
in CDF and D\O \ are discussed. For a charm tagging efficiency of about 10\%
and an integrated luminosity of 30~pb or more, it should be possible to
constrain the strange quark distribution function from production at the
Tevatron.Comment: submitted to Phys. Lett. B, Latex, 12 pages + 4 postscript figures
encoded with uufile, FSU-HEP-930812, MAD/TH/93-6, MAD/PH/788. A postscript
file with text and embedded figures is available via anonymous ftp at
hepsg1.physics.fsu.edu, file is /pub/keller/fsu-hep-930812.p
Statistical bounds on the dynamical production of entanglement
We present a random-matrix analysis of the entangling power of a unitary
operator as a function of the number of times it is iterated. We consider
unitaries belonging to the circular ensembles of random matrices (CUE or COE)
applied to random (real or complex) non-entangled states. We verify numerically
that the average entangling power is a monotonic decreasing function of time.
The same behavior is observed for the "operator entanglement" --an alternative
measure of the entangling strength of a unitary. On the analytical side we
calculate the CUE operator entanglement and asymptotic values for the
entangling power. We also provide a theoretical explanation of the time
dependence in the CUE cases.Comment: preprint format, 14 pages, 2 figure
Low energy dynamics of spinor condensates
We present a derivation of the low energy Lagrangian governing the dynamics
of the spin degrees of freedom in a spinor Bose condensate, for any phase in
which the average magnetization vanishes. This includes all phases found within
mean-field treatments except for the ferromagnet, for which the low energy
dynamics has been discussed previously. The Lagrangian takes the form of a
sigma model for the rotation matrix describing the local orientation of the
spin state of the gas
Applicability of self-consistent mean-field theory
Within the constrained Hartree-Fock (CHF) theory, an analytic condition is
derived to estimate whether a concept of the self-consistent mean field is
realized or not in level repulsive region. The derived condition states that an
iterative calculation of CHF equation does not converge when the quantum
fluctuations coming from two-body residual interaction and quadrupole
deformation become larger than a single-particle energy difference between two
avoided crossing orbits. By means of the numerical calculation, it is shown
that the analytic condition works well for a realistic case.Comment: 11 pages, 8 figure
Thermal states of the Kitaev honeycomb model: a Bures metric analysis
We analyze the Bures metric over the canonical thermal states for the Kitaev
honeycomb mode. In this way the effects of finite temperature on topological
phase transitions can be studied. Different regions in the parameter space of
the model can be clearly identified in terms of different temperature scaling
behavior of the Bures metric tensor. Furthermore, we show a simple relation
between the metric elements and the crossover temperature between the
quasi-critical and the quasi-classical regions. These results extend the ones
of [29,30] to finite temperatures.Comment: 6 pages, 2 figure
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