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Title: Neutrino scattering rates in neutron star matter with {delta} isobars

Abstract

We take the {delta}-isobar degrees of freedom into account in neutron star matter and evaluate their contributions to neutrino scattering cross sections and mean free paths. The neutron star matter is described by means of an effective hadronic model in the relativistic mean-field approximation. It is found that {delta} isobars may be present in neutron stars. The electron chemical potential does not decrease and the neutrino abundance does not increase with the increase of the density when neutrinos are trapped in the matter with {delta} isobars. The large vector coupling constant between the {delta}{sup -} and neutrino and the high spin of the {delta} influence significantly the neutrino scattering cross section and lead the contribution of the {delta}{sup -} to the dominance of the scattering rates. In neutrino-trapped case, the presence of {delta}s causes the neutrino mean free path to decrease drastically compared to that in the matter in which baryons are only nucleons.

Authors:
 [1];  [1];  [2];  [2];  [3];  [2];  [2]
  1. Department of Technical Physics, Peking University, Beijing 100871 (China)
  2. (China)
  3. Department of Physics, Peking University, Beijing 100871 (China)
Publication Date:
OSTI Identifier:
20995173
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevC.75.035806; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; APPROXIMATIONS; COUPLING CONSTANTS; CROSS SECTIONS; DEGREES OF FREEDOM; DENSITY; ELECTRONS; MATTER; MEAN FREE PATH; MEAN-FIELD THEORY; NEUTRINOS; NEUTRON STARS; NUCLEONS; RELATIVISTIC RANGE; SCATTERING; SPIN; TRAPPING; VECTORS

Citation Formats

Chen Yanjun, Guo Hua, MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871, Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000, Liu Yuxin, MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871, and Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000. Neutrino scattering rates in neutron star matter with {delta} isobars. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.035806.
Chen Yanjun, Guo Hua, MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871, Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000, Liu Yuxin, MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871, & Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000. Neutrino scattering rates in neutron star matter with {delta} isobars. United States. doi:10.1103/PHYSREVC.75.035806.
Chen Yanjun, Guo Hua, MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871, Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000, Liu Yuxin, MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871, and Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000. Thu . "Neutrino scattering rates in neutron star matter with {delta} isobars". United States. doi:10.1103/PHYSREVC.75.035806.
@article{osti_20995173,
title = {Neutrino scattering rates in neutron star matter with {delta} isobars},
author = {Chen Yanjun and Guo Hua and MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871 and Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000 and Liu Yuxin and MOE Key Laboratory of Heavy Ion Physics, Peking University, Beijing 100871 and Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000},
abstractNote = {We take the {delta}-isobar degrees of freedom into account in neutron star matter and evaluate their contributions to neutrino scattering cross sections and mean free paths. The neutron star matter is described by means of an effective hadronic model in the relativistic mean-field approximation. It is found that {delta} isobars may be present in neutron stars. The electron chemical potential does not decrease and the neutrino abundance does not increase with the increase of the density when neutrinos are trapped in the matter with {delta} isobars. The large vector coupling constant between the {delta}{sup -} and neutrino and the high spin of the {delta} influence significantly the neutrino scattering cross section and lead the contribution of the {delta}{sup -} to the dominance of the scattering rates. In neutrino-trapped case, the presence of {delta}s causes the neutrino mean free path to decrease drastically compared to that in the matter in which baryons are only nucleons.},
doi = {10.1103/PHYSREVC.75.035806},
journal = {Physical Review. C, Nuclear Physics},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • The {delta}-isobar degrees of freedom are taken into account in neutron star matter and their contributions to neutrino mean free paths are evaluated. It is found that the charged-current contributions are comparable to those from the neutral-current reactions. The contributions of {delta}-isobars may be a leading sector of neutrino opacities in neutron star matter, but the effects of the process in which the baryon transforms between nucleon and {delta} are unimportant.
  • The bulk viscosity of neutron-star matter, arising from the time lag in achieving beta equilibrium as the density is changed, is calculated. In the model used in standard cooling calculations, it is found, for the case of normal neutron matter, that the bulk viscosity goes as the sixth power of the temperature (as compared with a /ital T//sup /minus/2/ dependence for the shear viscosity), and that at temperatures above 10/sup 9/ K the bulk viscosity may dominate the dissipation term which regulates the gravitational-wave instability of rapidly rotating neutron stars. This raises the possibility that in the first years ofmore » a neutron-star's life the star could become unstable as the bulk viscosity decreases through cooling, with potentially observable consequences.« less
  • We study dense hadronic matter in a generalized relativistic mean field approach which contains nonlinear couplings of the {sigma}, {omega}, {rho}, {delta} fields and compare its predictions for properties of neutron stars with the corresponding results from different models found in the literature. Our predictions indicate a substantial modification in static global properties of nuclear matter and neutron stars with the inclusion of the {delta} meson into the formalism.
  • Random phase approximation calculations using a microscopic residual interaction (G matrix) are performed for /sup 16/O and /sup 12/C. The influence of ..delta.. isobars on isovector magnetic states is investigated and found to be small since many-body renormalization effects for the coupling of ph to ..delta..h states (g/sub NDelta//sup prime/) are considerably smaller in finite nuclei than in nuclear matter. Energies of isovector states and collective isoscalar states are described reasonably well. The electromagnetic transition strength is in general overestimated for both magnetic and electric transitions.