Circumstantial evidence for a soft nuclear symmetry energy at suprasaturation densities.
Within an isospin- and momentum-dependent hadronic transport model, it is shown that the recent FOPI data on the pi;{-}/pi;{+} ratio in central heavy-ion collisions at SIS/GSI energies [Willy Reisdorf, Nucl. Phys. A 781, 459 (2007)10.1016/j.nuclphysa.2006.10.085] provide circumstantial evidence suggesting a rather soft nuclear symmetry energy E_{sym}(rho) at rho> or =2rho_{0} compared to the Akmal-Pandharipande-Ravenhall prediction. Some astrophysical implications and the need for further experimental confirmations are discussed.
Xiao
Zhigang
Z
Department of Physics, Tsinghua University, Beijing 100084, PR China.
Li
Bao-An
BA
Chen
Lie-Wen
LW
Yong
Gao-Chan
GC
Zhang
Ming
M