154,254 research outputs found
Neutrino scattering in supernovae and spin correlations of a unitary gas
Core collapse supernova simulations can be sensitive to neutrino interactions
near the neutrinosphere. This is the surface of last scattering. We model the
neutrinosphere region as a warm unitary gas of neutrons. A unitary gas is a low
density system of particles with large scattering lengths. We calculate
modifications to neutrino scattering cross sections because of the universal
spin and density correlations of a unitary gas. These correlations can be
studied in laboratory cold atom experiments. We find significant reductions in
cross sections, compared to free space interactions, even at relatively low
densities. These reductions could reduce the delay time from core bounce to
successful explosion in multidimensional supernova simulations.Comment: 5 pages, 2 figures, minor corrections in response to referee, Phys.
Rev. C in pres
Theoretical study of corrugated plates - Shearing of a trapezoidally corrugated plate with trough lines held straight
Mathematical model for elastic shear bending of trapezoidally corrugated plate with trough lines held straight including stiffness and stress analysi
Nonuniversal Effects in the Homogeneous Bose Gas
Effective field theory predicts that the leading nonuniversal effects in the
homogeneous Bose gas arise from the effective range for S-wave scattering and
from an effective three-body contact interaction. We calculate the leading
nonuniversal contributions to the energy density and condensate fraction and
compare the predictions with results from diffusion Monte Carlo calculations by
Giorgini, Boronat, and Casulleras. We give a crude determination of the
strength of the three-body contact interaction for various model potentials.
Accurate determinations could be obtained from diffusion Monte Carlo
calculations of the energy density with higher statistics.Comment: 24 pages, RevTex, 5 ps figures, included with epsf.te
Axial Anomaly and the Nucleon Spin
In this letter, we have taken a particular Lagrangian, which was introduced
to resolve U(1) problem, as an effective QCD Lagrangian, and have derived a
formula of the quark content of the nucleon spin. The difference between quark
content of the proton (\Delta\Sigma_p) and that of the neutron (\Delta\Sigma_n)
is evaluated by this formula. Neglecting the higher-order isospin corrections,
this formula can reduce to Efremov's results in the large N_c limit.Comment: (1) A few changes and corrections made following Referee. (2) The
difference between quark content of the proton (\Delta\Sigma_p) and that of
the neutron (\Delta\Sigma_n) is evaluated. Neglecting the higher-order
isospin corrections, this formula can reduce to Efremov's results in the
large N_c limi
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