Constraining the symmetry energy with heavy-ion collisions and Bayesian analyses

Efficiency corrected single ratios of neutron and proton spectra in central Sn112+112Sn and Sn124+124Sn collisions at 120 MeV/u are combined with double ratios to provide constraints on the density and momentum dependencies of the isovector mean-field potential. Bayesian analyses of these data reveal that the isoscalar and isovector nucleon effective masses, ms⁎−mv⁎ are strongly correlated. The linear correlation observed in ms⁎−mv⁎ yields a nearly independent constraint on the effective mass splitting Δmnp⁎=(mn⁎−mp⁎)/mN=−0.05−0.09+0.09δ. The correlated constraint on the standard symmetry energy, S0 and the slope, L at saturation density yields the values of symmetry energy S(ρs)=16.8−1.2+1.2 MeV at a sensitive density of ρs/ρ0=0.43−0.05+0.05.