1,365 research outputs found
Divergence terms in the supertrace heat asymptotics for the de Rham complex on a manifold with boundary
We use invariance theory to determine the coefficient
in the supertrace for the twisted de Rham complex with absolute boundary
conditions.Comment: 19 pages, LaTeX, Theorem 1.2 correcte
Families of exact solutions of a 2D gravity model minimally coupled to electrodynamics
Three families of exact solutions for 2-dimensional gravity minimally coupled
to electrodynamics are obtained in the context of theory. It is
shown, by supersymmetric formalism of quantum mechanics, that the quantum
dynamics of a neutral bosonic particle on static backgrounds with both varying
curvature and electric field is exactly solvable.Comment: 13 pages, LaTeX, to be published in JM
ARE LOWER-INCOME SHOPPERS AS PRICE SENSITIVE AS HIGHER-INCOME ONES?: A LOOK AT BREAKFAST CEREALS
Scanner data for breakfast cereals are used to estimate demand elasticities for six supermarket stores in two distinct socio-economic areas. Three stores are in low-income locations and three are in high-income locations. A time series cross-section model is estimated for five product categories across six cross sections over forty-two weeks. Results show lower-income shoppers to have more elastic demands for four of the five product categories: private label cold cereals, the top ten brands of cold cereals, all other brands of cold cereals, and hot cereals. Price is not statistically significant for a fifth product category, snack cereals.Consumer/Household Economics,
Orbital disorder induced by charge fluctuations in vanadium spinels
Motivated by recent experiments on vanadium spinels, VO, that show
an increasing degree of electronic delocalization for smaller cation sizes, we
study the evolution of orbital ordering (OO) between the strong and
intermediate-coupling regimes of a multi-orbital Hubbard Hamiltonian. The
underlying magnetic ordering of the Mott insulating state leads to a rapid
suppression of OO due to enhanced charge fluctuations along ferromagnetic
bonds. Orbital double-occupancy is rather low at the transition point
indicating that the system is in the crossover region between strong and
intermediate-coupling regimes when the orbital degrees of freedom become
disordered
Parametric hypersensitivity in many-body bath-mediated transport: The quantum Rabi model
We demonstrate that non-equilibrium steady states of the dissipative Rabi
model show dramatic spikes in transport rates over narrow parameter ranges.
Similar results are found for the Holstein and Dicke models. This is found to
be due to avoided energy level crossings in the corresponding closed systems,
and correlates with spikes in the entanglement entropy of key eigenstates, a
signature of strong mixing and resonance among system degrees of freedom.
Further, contrasting the Rabi model with the Jaynes-Cummings model reveals this
behavior as being related to quantum integrability.Comment: 5 pages, 4 figure
Chern-kernels and anomaly cancellation in M-theory
This paper deals with magnetic equations of the type dH=J where the current J
is a delta-function on a brane worldvolume and H a p-form field strength. In
many situations in M-theory this equation needs to be solved for H in terms of
a potential. A standard universality class of solutions, involving
Dirac-branes, gives rise to strong intermediate singularities in H which in
many physically relevant cases lead to inconsistencies. In this paper we
present an alternative universality class of solutions for magnetic equations
in terms of Chern-kernels, and provide relevant applications, among which the
anomaly-free effective action for open M2-branes ending on M5-branes. The
unobservability of the Dirac-brane requires a Dirac quantization condition; we
show that the requirement of ``unobservability'' of the Chern-kernel leads in
M-theory to classical gravitational anomalies which cancel precisely their
quantum counterparts.Comment: LaTex, 39 pages, references and comments adde
The caloron correspondence and higher string classes for loop groups
We review the caloron correspondence between -bundles on
and -bundles on , where is the space of smooth loops in
the compact Lie group . We use the caloron correspondence to define
characteristic classes for -bundles, called string classes, by
transgression of characteristic classes of -bundles. These generalise the
string class of Killingback to higher dimensional cohomology.Comment: 21 pages. Author addresses adde
Topology of Entanglement Evolution of Two Qubits
The dynamics of a two-qubit system is considered with the aim of a general
categorization of the different ways in which entanglement can disappear in the
course of the evolution, e.g., entanglement sudden death. The dynamics is
described by the function ~n(t), where ~n is the 15-dimensional polarization
vector. This representation is particularly useful because the components of ~n
are direct physical observables, there is a meaningful notion of orthogonality,
and the concurrence C can be computed for any point in the space. We analyze
the topology of the space S of separable states (those having C = 0), and the
often lower-dimensional linear dynamical subspace D that is characteristic of a
specific physical model. This allows us to give a rigorous characterization of
the four possible kinds of entanglement evolution. Which evolution is realized
depends on the dimensionality of D and of D \cap S, the position of the
asymptotic point of the evolution, and whether or not the evolution is
"distance-Markovian", a notion we define. We give several examples to
illustrate the general principles, and to give a method to compute critical
points. We construct a model that shows all four behaviors.Comment: 15 pages, 11 figures, 2 tabl
Classical Topological Order in Kagome Ice
We examine the onset of classical topological order in a nearest-neighbor
kagome ice model. Using Monte Carlo simulations, we characterize the
topological sectors of the groundstate using a non-local cut measure which
circumscribes the toroidal geometry of the simulation cell. We demonstrate that
simulations which employ global loop updates that are allowed to wind around
the periodic boundaries cause the topological sector to fluctuate, while
restricted local loop updates freeze the simulation into one topological
sector. The freezing into one topological sector can also be observed in the
susceptibility of the real magnetic spin vectors projected onto the kagome
plane. The ability of the susceptibility to distinguish between fluctuating and
non-fluctuating topological sectors should motivate its use as a local probe of
topological order in a variety of related model and experimental systems.Comment: 17 pages, 9 figure
A covariant formalism for Chern-Simons gravity
Chern--Simons type Lagrangians in dimensions are analyzed from the
point of view of their covariance and globality. We use the transgression
formula to find out a new fully covariant and global Lagrangian for
Chern--Simons gravity: the price for establishing globality is hidden in a
bimetric (or biconnection) structure. Such a formulation allows to calculate
from a global and simpler viewpoint the energy-momentum complex and the
superpotential both for Yang--Mills and gravitational examples.Comment: 12 pages,LaTeX, to appear in Journal of Physics
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