Constraining simultaneously nuclear symmetry energy and neutron-proton effective mass splitting with nucleus giant resonances using a dynamical approach

摘要

With a newly improved isospin- and momentum-dependent interaction and an isospin-dependent Boltzmann- Uehling-Uhlenbeck transport model, we have investigated the effects of the slope parameter L of the nuclear symmetry energy and the isospin splitting of the nucleon effective mass m_(n-p)~*= (m_n~*-m_p~*)/m on the centroid energy of the isovector giant dipole resonance and the electric dipole polarizability in ~(208)Pb. With the isoscalar nucleon effective mass m_s~*= 0.7m constrained by the empirical optical potential, we obtain a constraint of L = 64.29 ± 11.84 (MeV) and m_(n-p)~*= (-0.019 ± 0.090)δ, with δ being the isospin asymmetry of nuclear medium. With the isoscalar nucleon effective mass m_s~*= 0.84m extracted from the excitation energy of the isoscalar giant quadruple resonance in ~(208)Pb,we obtain a constraint ofL = 53.85 ± 10.29 (MeV) and m_(n-p)~*= (0.216 ± 0.114)δ.