7,948 research outputs found
Effect of viscosity and thermal conductivity on the radial oscillation and relaxation of relativistic stars
In this paper we present a generic formulation of the linearized dynamical
equations governing small adiabatic radial oscillations of relativistic stars.
The dynamical equations are derived by taking into consideration those effects
of viscosity and thermal conductivity of neutron-star matter which directly
determine the minimum period of observable pulsars. A variational principle is
applied to determine a discrete set of eigenfunctions with complex eigenvalues.
The real and imaginary parts of eigenvalues represent the squared natural
frequencies and relaxation time of radial oscillations of non-rotating neutron
stars, respectively. We provide a suitable framework which may be supplemented
with various potential species of cold-nuclear-matter models to compute the
spectra of the normalized eigenfrequencies with a certain numerical precision.
In the last section, we provide a qualitative estimation of the rate at which
viscosity and thermal conductivity drain the kinetic energy of radial
oscillation mode in reasonably uniform neutron stars, without relying on
explicit numerical computations
Quantum -divergence preserving maps on positive semidefinite operators acting on finite dimensional Hilbert spaces
We determine the structure of all bijections on the cone of positive
semidefinite operators which preserve the quantum -divergence for an
arbitrary strictly convex function defined on the positive halfline. It
turns out that any such transformation is implemented by either a unitary or an
antiunitary operator.Comment: v2: some typos corrected v3: improved presentation and some new
references v4: accepted manuscript versio
PHENIX results on Bose-Einstein correlation functions
Measurement of Bose-Einstein or HBT correlations of identified charged
particles provide insight into the space-time structure of particle emitting
sources in heavy-ion collisions. In this paper we present the latest results
from the RHIC PHENIX experiment on such measurements.Comment: 4 pages, 3 figures, WPCF-2015 conference proceeding
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