5,098 research outputs found
Commentary on "A Man of No Substance: The Philosopher in Plato's Gorgias," by S. Montgomery Ewegen
Topological Phases emerging from Spin-Orbital Physics
We study the evolution of spin-orbital correlations in an inhomogeneous
quantum system with an impurity replacing a doublon by a holon orbital degree
of freedom. Spin-orbital entanglement is large when spin correlations are
antiferromagnetic, while for a ferromagnetic host we obtain a pure orbital
description. In this regime the orbital model can be mapped on spinless
fermions and we uncover topological phases with zero energy modes at the edge
or at the domain between magnetically inequivalent regions.Comment: 6 pages, 5 figures, submitte
Doping dependence of magnetic excitations of 1D cuprates as probed by Resonant Inelastic x-ray Scattering
We study the dynamical, momentum dependent two- and four-spin response
functions in doped and undoped 1D cuprates, as probed by resonant inelastic
x-ray scattering, using an exact numerical diagonalization procedure. In the
undoped system the four-spin response vanishes at , whereas the
two-spin correlator is peaked around , with generally larger spectral
weight. Upon doping spectra tend to soften and broaden, with a transfer of
spectral weight towards higher energy. However, the total spectral weight and
average peak position of either response are only weakly affected by doping up
to a concentration of 1/8. Only the two-spin response at changes
strongly, with a large reduction of spectral weight and enhancement of
excitation energy. At other momenta the higher-energy, generic features of the
magnetic response are robust against doping. It signals the presence of strong
short-range antiferromagnetic correlations, even after doping mobile holes into
the system. We expect this to hold also in higher dimensions.Comment: 7 pages, 5 figure
Criteria for Bayesian model choice with application to variable selection
In objective Bayesian model selection, no single criterion has emerged as
dominant in defining objective prior distributions. Indeed, many criteria have
been separately proposed and utilized to propose differing prior choices. We
first formalize the most general and compelling of the various criteria that
have been suggested, together with a new criterion. We then illustrate the
potential of these criteria in determining objective model selection priors by
considering their application to the problem of variable selection in normal
linear models. This results in a new model selection objective prior with a
number of compelling properties.Comment: Published in at http://dx.doi.org/10.1214/12-AOS1013 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Small Angle Polarization in High Energy P--P Scattering Through Nonperturbative Chiral Symmetry Breaking
We show that a large anomalous contribution due to nonperturbative
instanton-like gluonic field configurations to the axial charge of the proton
implies high-energy spin effects in elastic scattering. This is the same
mechanism which is responsible for anomalous baryon number violation at high
energy in the standard model. We compute the proton polarization due to these
effects and we show that it is proportional to the center-of-mass scattering
angle with a universal (energy-independent) slope of order unity.Comment: (13 pages, 2 figures
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