标题： 用S$π$RIT实验中的流和停止观测约束核子有效质量 显示英文标题

标题： Constraining nucleon effective masses with flow and stopping observables from the S$π$RIT experiment

摘要： 核状态方程(EoS)的性质可以通过测量核-核碰撞的动力学特性来探究。 在本研究中，我们展示了在270 AMeV下固定靶Sn + Sn碰撞中测得的定向流($v_1$)、椭圆流($v_2$)和停止(VarXZ)，使用的是S$\pi$RIT时间投影室。 我们进行了贝叶斯分析，在改进的量子分子动力学-斯科尔米尔(ImQMD-Sky)输运代码中同时变化EoS参数，以获得多变量相关约束。 变化的参数包括对称能，$S_0$，以及饱和密度处对称能的斜率，$L$，标量有效质量，$m_{s}^*/m_{N}$，矢量有效质量，$m_{v}^{*}/m_{N}$以及介质中的截面增强因子$\eta$。 我们发现流和 VarXZ 观测量对质子和中子有效质量的分裂以及介质中的截面敏感。 ImQMD-Sky预测与S$\pi$RIT数据的比较表明，$m_{s}^*/m_{N}$、$m_{v}^{*}/m_{N}$和$\eta$有狭窄的优选值范围。 显示英文摘要

摘要： Properties of the nuclear equation of state (EoS) can be probed by measuring the dynamical properties of nucleus-nucleus collisions. In this study, we present the directed flow ($v_1$), elliptic flow ($v_2$) and stopping (VarXZ) measured in fixed target Sn + Sn collisions at 270 AMeV with the S$\pi$RIT Time Projection Chamber. We perform Bayesian analyses in which EoS parameters are varied simultaneously within the Improved Quantum Molecular Dynamics-Skyrme (ImQMD-Sky) transport code to obtain a multivariate correlated constraint. The varied parameters include symmetry energy, $S_0$, and slope of the symmetry energy, $L$, at saturation density, isoscalar effective mass, $m_{s}^*/m_{N}$, isovector effective mass, $m_{v}^{*}/m_{N}$ and the in-medium cross-section enhancement factor $\eta$. We find that the flow and VarXZ observables are sensitive to the splitting of proton and neutron effective masses and the in-medium cross-section. Comparisons of ImQMD-Sky predictions to the S$\pi$RIT data suggest a narrow range of preferred values for $m_{s}^*/m_{N}$, $m_{v}^{*}/m_{N}$ and $\eta$.