相对论重离子对撞机中定向流的系统尺寸无关性
System-size independence of directed flow at the Relativistic Heavy-Ion Collider
摘要：
我们测量定向流（$v_1$）在金+金和铜+铜碰撞在$\sqrt{s_{NN}} =$ 200 GeV和62.4 GeV的带电粒子，作为赝快度（$η$），横向动量（$p_t$）和碰撞中心的函数，从STAR实验的数据的基础上。我们发现，定向流依赖于入射能量，但与所有现有的模型，而不是在一个给定的中心碰撞系统的大小。我们扩展的有效性限制碎裂的概念，不同的碰撞系统，并调查可能的解释所观察到的符号变化$v_1(p_t)$。
英文摘要：
We measure directed flow ($v_1$) for charged particles in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}} =$ 200 GeV and 62.4 GeV, as a function of pseudorapidity ($η$), transverse momentum ($p_t$) and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all existing models, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to different collision systems, and investigate possible explanations for the observed sign change in $v_1(p_t)$.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
