Effects of Tensor Couplings on Nucleonic Direct URCA Processes in Neutron Star Matter
Yan Xu1**, Xiu-Lin Huang1,3**, Cheng-Zhi Liu1**, Tmurbagan Bao2, Guang-Zhou Liu3
1Changchun Observatory, National Astronomical Observatories, Chinese Academy of Sciences, Changchun 130117 2College of Physics and Electronic Information, Inner Mongolia University for the Nationalities, Tongliao 028043 3Center for Theoretical Physics, Jilin University, Changchun 130012
Abstract：The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree–Fock approximation. We particularly study the influences of the tensor couplings of vector mesons $\omega$ and $\rho$ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons $\omega$ and $\rho$ can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons $\omega$ and $\rho$ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non-superfluid neutron star matter. However, when considering only the tensor coupling of vector meson $\rho$, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson $\rho$ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.
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2016, Vol. 33 
