The role of the delta isobar degrees of freedom in nucleon–nucleon scattering is revisited.We attempt to understand why the dimensionally regularized two-pion exchanges with the explicit delta isobar is much stronger...The role of the delta isobar degrees of freedom in nucleon–nucleon scattering is revisited.We attempt to understand why the dimensionally regularized two-pion exchanges with the explicit delta isobar is much stronger than the ones with spectral function regularization.When the cutoff value of spectral function regularization is varied,the isoscalar central component exhibits a rather large cut-off variation.This reveals a surprisingly large numerical factor of the deltaful two-pion exchange potentials.The power counting is adjusted accordingly and we discuss the results and how to improve upon this finding.展开更多
In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can oc...In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can occur at relative shallow optical potential depth of K^ from -80 MeV to -160 MeV. Both K^- and K^0 condensations favor the appearances of △ resonances. With K^- condensations all the △ quartet can appear well inside the maximum mass stars. The appearances of △ resonances change the composition and distribution of particles at high densities. The populations of △ resonances can enhance K^- condensation. It is found that in the core of massive neutron stars, neutron star matter includes rich particle species, such as antikaons, baryon octet, and △ quartet. In the presence of △ resonances and K^- condensation, the EOS becomes softer and results in smaller maximum mass stars. Furthermore the impact of antikaon condensations, hyperons, and △ resonances on direct Urca process with nucleons is also discussed briefly.展开更多
We study the structure of nonstrange baryons by analytically calculating the electromagnetic transition helicity amplitudes of the nucleon andΔresonances.We employ an improved hypercentral constituent quark model and...We study the structure of nonstrange baryons by analytically calculating the electromagnetic transition helicity amplitudes of the nucleon andΔresonances.We employ an improved hypercentral constituent quark model and obtain the corresponding eigenenergies and eigenfunctions in closed forms.Then,we calculate the transverse and longitudinal helicity amplitudes for nucleon andΔresonances.The comparison of evaluated observables and experimental data indicates good agreement between the proposed model and available data.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.12275185,12335002(BL),and 12347154(RP)。
文摘The role of the delta isobar degrees of freedom in nucleon–nucleon scattering is revisited.We attempt to understand why the dimensionally regularized two-pion exchanges with the explicit delta isobar is much stronger than the ones with spectral function regularization.When the cutoff value of spectral function regularization is varied,the isoscalar central component exhibits a rather large cut-off variation.This reveals a surprisingly large numerical factor of the deltaful two-pion exchange potentials.The power counting is adjusted accordingly and we discuss the results and how to improve upon this finding.
基金Supported in part by National Natural Science Foundation of China under Grant Nos.10275029 and 10675054
文摘In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can occur at relative shallow optical potential depth of K^ from -80 MeV to -160 MeV. Both K^- and K^0 condensations favor the appearances of △ resonances. With K^- condensations all the △ quartet can appear well inside the maximum mass stars. The appearances of △ resonances change the composition and distribution of particles at high densities. The populations of △ resonances can enhance K^- condensation. It is found that in the core of massive neutron stars, neutron star matter includes rich particle species, such as antikaons, baryon octet, and △ quartet. In the presence of △ resonances and K^- condensation, the EOS becomes softer and results in smaller maximum mass stars. Furthermore the impact of antikaon condensations, hyperons, and △ resonances on direct Urca process with nucleons is also discussed briefly.
文摘We study the structure of nonstrange baryons by analytically calculating the electromagnetic transition helicity amplitudes of the nucleon andΔresonances.We employ an improved hypercentral constituent quark model and obtain the corresponding eigenenergies and eigenfunctions in closed forms.Then,we calculate the transverse and longitudinal helicity amplitudes for nucleon andΔresonances.The comparison of evaluated observables and experimental data indicates good agreement between the proposed model and available data.
