论文标题
限制超级核核冲突的初始阶段
Constraining the initial stages of ultrarelativistic nuclear collisions
论文作者
论文摘要
人们经常认为，在重型离子碰撞中产生的夸克 - 格鲁隆等离子体在早期会进行免费流媒体。我们基于以下假设来研究这个问题：通用吸引子在最早的阶段占主导地位的动态，该阶段提供了一种将初始状态与流体动力扩展的开始的方法，以近似但概念上透明的方式连接起来。我们证明，测得的粒子多重性的中心性依赖性可用于定量约束压力各向异性，并发现它在很大程度上取决于初始能量沉积的模型。作为例证，我们比较了三个初始状态模型，并表明它们预测了压力各向异性的早期值。这强烈表明，假设在流体动物化之前进行自由流媒体不一定与通用初始状态模型兼容，并且在流动力流前流的特征需要与初始状态的模型相匹配。
It is frequently supposed that quark-gluon plasma created in heavy-ion collisions undergoes free streaming at early times. We examine this issue based on the assumption that a universal attractor dominates the dynamics already at the earliest stages, which offers a way to connect the initial state with the start of the hydrodynamic expansion in an approximate but conceptually transparent fashion. We demonstrate that the centrality dependence of the measured particle multiplicities can be used to quantitatively constrain the pressure anisotropy and find that it strongly depends on the model of the initial energy deposition. As an illustration, we compare three initial state models and show that they predict rather different early-time values of the pressure anisotropy. This strongly suggests that assuming free streaming prior to hydrodynamization is not necessarily compatible with a generic initial state model and that features of the pre-hydrodynamic flow need to be matched with the model of the initial state.
