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

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 Pb-208. 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) delta, with delta 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 Pb-208, we obtain a constraint of L = 53.85 +/- 10.29 (MeV) and m*(n-p) = (0.216 +/- 0.114) delta.