标题： 重离子碰撞中的局域平衡。 微观模型与统计模型分析 显示英文标题

标题： Local equilibrium in heavy ion collisions. Microscopic model versus statistical model analysis

摘要： 在从10.7AGeV（AGS）到160AGeV（SPS）的能量范围内，相对论重离子碰撞中局域均衡假设在微观传输模型中被检验。 针对反应中的中心单元进行的动力学计算与热统计模型的预测进行了比较。 我们发现，在AGS能量下，当时间达到$t \geq 10$fm/$c$时，在中心单元中的膨胀强子物质接近于动能、热能和化学平衡。 此时状态方程可以用简单的依赖关系$P \cong (0.12-0.15) \epsilon$近似。 随着能量增加到40AGeV和160AGeV，我们观察到强子的产额和能量谱与统计模型值之间的偏差逐渐增大。 这些局部均衡的违反表明，即使在高于10AGeV的能量下重离子碰撞的中心单元中，完全均衡的状态也没有达到。 这些发现的根源可以追溯到弦的多粒子衰变以及共振的多体衰变。 显示英文摘要

摘要： The assumption of local equilibrium in relativistic heavy ion collisions at energies from 10.7 AGeV (AGS) up to 160 AGeV (SPS) is checked in the microscopic transport model. Dynamical calculations performed for a central cell in the reaction are compared to the predictions of the thermal statistical model. We find that kinetic, thermal and chemical equilibration of the expanding hadronic matter are nearly approached late in central collisions at AGS energy for $t \geq 10$ fm/$c$ in a central cell. At these times the equation of state may be approximated by a simple dependence $P \cong (0.12-0.15) \epsilon$. Increasing deviations of the yields and the energy spectra of hadrons from statistical model values are observed for increasing energy, 40 AGeV and 160 AGeV. These violations of local equilibrium indicate that a fully equilibrated state is not reached, not even in the central cell of heavy ion collisions at energies above 10 AGeV. The origin of these findings is traced to the multiparticle decays of strings and many-body decays of resonances.