摘要
The presence of the isovector scalar interaction in neutron star matter is considered by exchangingδmeson;we study the effects ofδmesons on the direct Urca processes involving hyperons.The calculation is based on the framework of the relativistic mean field theory.By our analysis,the hyperon direct Urca processes under beta equilibrium are open at lower densities due toδmesons,which create a larger energy gap between two baryons in the reactions.Theδmeson leads to an obvious enhancement of the neutrino emissivity for the hyperon direct Urca processes.In particular,the relativistic neutrino emissivity is found to be substantially larger than predicted in the nonrelativistic approach whetherδmesons appear in an neutron star or not.In our results,δmesons not only change the baryons properties,but also result in more rapid cooling rate of neutron stars by hyperon direct Urca processes.
The presence of the isovector scalar interaction in neutron star matter is considered by exchanging δ meson; we study the effects of δ mesons on the direct Urca processes involving hyperons. The calculation is based on the framework of the relativistic mean field theory. By our analysis, the hyperon direct Urca processes under beta equilibrium are open at lower densities due to δ mesons. which create a larger energy gap between two baryons in the reactions. The δ meson leads to all obvious enhancement of the neutrino emissivity for the hyperon direct Urca processes. In particullar, the relativistic neutrino emissivity is found to be substantially larger than predicted in the nonrelativistic approach whether δ mesons appear in an neutron star or not. In our results, δ mesons not only change the baryons properties, but also result in more rapid cooling rate of neutron stars by hyperon direct Urca processes.
基金
partially supported by the National Natural Science Foundation of China(11075063,11073033,11247312,and 11103047)
