Constraining neutron-proton effective mass splitting and density dependence of nuclear symmetry energy using heavy-ion collisions

While significant progress has been made in understaning the density and momentum depenence of nuclear isovector interaction and the correspodning symmetry energy of neutron-rich nucleonic matter around saturation density, many challenging questions remain to be addressed especially at supra-saturation densities [1]. According to the Hugenholtz-Van Hove theorem [2], nuclear symmetry energy and its slope L are determined by the nucleon isovector (symmetry) potential and its momentum dependence [3]. The latter determines uniquely the neutron-proton effective k-mass splitting in neutron-rich nucleonic matter. Using currently available constraints on the symmetry energy from 28 recent analyses of various terrestrial nuclear laboratory experiments and astrophysical observations, we infer the corresponding neutron-proton effective k-mass splitting [4] and discuss potentially useful observables for further improving the constraints using heavy-ion reactions.\\[4pt] [1] B.A. Li, L.W. Chen and C.M. Ko, Phys. Rep. 464, 113 (2008).\\[0pt] [2] N.M. Hugenholtz and L. van Hove, Physica 24, 363 (1958).\\[0pt] [3] C. Xu, B.A. Li and L.W. Chen, Phys. Rev. C82, 054607 (2010).\\[0pt] [4] B.A. Li and X. Han, Phys. Lett. B727, 276 (2013).