Nuclear collective flows produced in semicentral heavy ion collisions at intermediate energies and their dependence on the momentumdependent symmetry potential has been investigated within the isospindependent quantum molecular dynamics (IQMD) transport model by theory physics group at Institute of Modern Physics (IMP), CAS. Important progress has been obtained in this work. It is known that the nuclear collective flows, such as the directed and elliptic flows, are the useful tool for studying the equation of state of symmetry and asymmetry nuclear matter. Generally speaking, due to the interactions among nucleons, a nucleon deviates from its free mass in the medium. There will be the neutronproton effective mass splitting if the isospin effects are considered. In the nonrelativistic framework, momentumdependent symmetry potential is closely related to the neutronproton effective mass splitting. The positive or negative signs of neutronproton effective mass splitting correspond to completely different momentumdependent symmetry potential. The researchers have to constrain the nucleon mass splitting before constraining the momentumdependent symmetry potential. Based on the IQMD model, in which the isospin effects in the momentum dependent interactions are incorporated, the directed and elliptic flows of protons and light cluster with mass number of A=3 produced in semicentral AuAu collisions in the energy range from 250 to 800A MeV are calculated. It is found that theoretical calculations can reproduce the experimental data of the FOPI Collaboration. Neutronproton differential flow and the difference of neutronproton directed and elliptic flows are sensitive to the momentumdependent symmetry potential, especially at larger momenta and rapidities. Moreover, this sensitivity is independent on both the isoscalar part of nuclear equation of state and inmedium cross sections. Thus Neutronproton differential flow and the difference of neutronproton directed and elliptic flows is the effective tool to extract the information of the momentumdependent symmetry potential and neutronproton effective mass splitting. The results have been published in Physical Review C 91, 054609 (2015). This work was supported by the Major State Basic Research Development Program in China (Nos 2014CB845405 and 2015CB856903), the National Natural Science Foundation of China Projects (Nos 11175218 and U1332207). The article can be linked as follows: http://link.aps.org/doi/10.1103/PhysRevC.91.054609 Fig. 1 Rapidity distributions of directed flow of protons produced in semicentral AuAu collisions at 250, 400, 600 and 800A MeV.(Image by IMP) Fig. 2 Transverse momentum distributions of the difference of neutronproton elliptic flow in semicentral AuAu collisions at 250, 600 and 800A MeV.(Image by IMP)
