title: Circumstantial evidence for a soft nuclear symmetry energy at suprasaturation densities.
abstract: 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.
authors.affiliation: Department of Physics, Tsinghua University, Beijing 100084, PR China.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Xiao
authors.forename: Bao-An
authors.initials: BA
authors.lastname: Li
authors.forename: Lie-Wen
authors.initials: LW
authors.lastname: Chen
authors.forename: Gao-Chan
authors.initials: GC
authors.lastname: Yong
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang