1,639 research outputs found
Low temperature behavior of the heavy Fermion Ce3Co4Sn13
The compound Ce3Co4Sn13 is an extremely heavy cubic heavy fermion system with
a low temperature electronic specific heat of order ~4 J/mol-K2. If the
compound is nonmagnetic, it would be one of the heaviest nonmagnetic Ce-based
heavy fermions reported to date and therefore would be expected to lie
extremely close to a quantum critical point. However, a broad peak of unknown
origin is observed at 0.8 K in the specific heat and magnetic susceptibility,
suggesting the possibility of antiferromagnetic order. We present neutron
diffraction data from polycrystalline samples which do not show any sign of
magnetic scattering below 0.8 K. In addition, we present inelastic neutron
scattering data from a single crystal sample which is consistent with the 1.2 K
energy scale for Kondo spin fluctuations determined from specific heat
measurements.Comment: 4 pages, 2 figures, submitted to J. Mag. Mag. Mater. for ICM 200
Cold Compressed Baryonic Matter with Hidden Local Symmetry and Holography
I describe a novel phase structure of cold dense baryonic matter predicted in
a hidden local symmetry approach anchored on gauge theory and in a holographic
dual approach based on the Sakai-Sugimoto model of string theory. This new
phase is populated with baryons with half-instanton quantum number in the
gravity sector which is dual to half-skyrmion in gauge sector in which chiral
symmetry is restored while light-quark hadrons are in the color-confined phase.
It is suggested that such a phase that aries at a density above that of normal
nuclear matter and below or at the chiral restoration point can have a drastic
influence on the properties of hadrons at high density, in particular on
short-distance interactions between nucleons, e.g., multi-body forces at short
distance and hadrons -- in particular kaons -- propagating in a dense medium.
Potentially important consequences on the structure of compact stars will be
predicted.Comment: 15 pages, to appear in proceedings of "Strong Coupling Gauge Theories
in LHC Era (SCGT09)," Nagoya, Japa
Deep sub-wavelength nanofocusing of UV-visible light by hyperbolic metamaterials
Confining light into a sub-wavelength area has been challenging due to the natural phenomenon of diffraction. In this paper, we report deep sub-wavelength focusing via dispersion engineering based on hyperbolic metamaterials. Hyperbolic metamaterials, which can be realized by alternating layers of metal and dielectric, are materials showing opposite signs of effective permittivity along the radial and the tangential direction. They can be designed to exhibit a nearly-flat open isofrequency curve originated from the large-negative permittivity in the radial direction and small-positive one in the tangential direction. Thanks to the ultraflat dispersion relation and curved geometry of the multilayer stack, hyperlens can magnify or demagnify an incident beam without diffraction depending on the incident direction. We numerically show that hyperlens-based nanofocusing device can compress a Gaussian beam down to tens-of-nanometers of spot size in the ultraviolet (UV) and visible frequency range. We also report four types of hyperlenses using different material combinations to span the entire range of visible frequencies. The nanofocusing device based on the hyperlens, unlike conventional lithography, works under ordinary light source without complex optics system, giving rise to practical applications including truly nanoscale lithography and deep sub-wavelength scale confinement.1165Nsciescopu
The Gluon Spin in the Chiral Bag Model
We study the gluon polarization contribution at the quark model
renormalization scale to the proton spin, , in the chiral bag model. It
is evaluated by taking the expectation value of the forward matrix element of a
local gluon operator in the axial gauge . It is shown that the confining
boundary condition for the color electric field plays an important role. When a
solution satisfying the boundary condition for the color electric field, which
is not the conventionally used but which we favor, is used, the has a
positive value for {\it all} bag radii and its magnitude is comparable to the
quark spin polarization. This results in a significant reduction in the
relative fraction of the proton spin carried by the quark spin, which is
consistent with the small flavor singlet axial current measured in the EMC
experiments.Comment: Corrections to figure
Cold Dense Baryonic Matter and Compact Stars
Probing dense hadronic matter is thus far an uncharted field of physics. Here
we give a brief summary of the highlights of what has been so far accomplished
and what will be done in the years ahead by the World Class University III
Project at Hanyang University in the endeavor to unravel and elucidate the
multifacet of the cold dense baryonic matter existing in the interior of the
densest visible stable object in the Universe, i.e., neutron stars, strangeness
stars and/or quark stars, from a modest and simplified starting point of an
effective field theory modeled on the premise of QCD as well as from a gravity
dual approach of hQCD. The core of the matter of our research is the possible
origin of the of the proton mass that is to be accounted for and how
the "vacuum" can be tweaked so that the source of the mass generation can be
uncovered by measurements made in terrestrial as well as space laboratories.
Some of the issues treated in the program concern what can be done - both
theoretically and experimentally - in anticipation of what's to come for basic
physics research in Korea.Comment: 23 pages, 8 figures; Based on the review prepared for the "2011 World
Class University (WCU) International Conference," August 2011, Seoul, Kore
Demonstration of nanoimprinted hyperlens array for high-throughput sub-diffraction imaging
11124Nsciescopu
A Schematic Model for Mixing at Finite Density and In-Medium Effective Lagrangian
Based on schematic two-level models extended to -meson degrees of freedom, we investigate possible mechanisms of chiral restoration in the vector/axial-vector channels in cold nuclear matter. In the first part of this article we employ the massive Yang-Mills framework to construct an effective chiral Lagrangian based on low-energy mesonic modes at finite density. The latter are identified through nuclear collective excitations of `meson'-sobar type such as , type treatment the in-medium gauge coupling , the (axial-) vector meson masses and are found to decrease with density indicating the approach towards chiral restoration phase in the language of in-medium effective fields. In the second part of our analysis, we evaluate the (first) in-medium Weinberg sum rule which relates vector and axial-vector correlators to the pion decay constant. Using in-medium / spectral functions (computed in the two-level model) also leads to a substantial reduction of the pion decay constant with increasing density
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