"Figure 2" of "Beam-Energy and System-Size Dependence of Dynamical Net Charge Fluctuations"

We present measurements of net charge fluctuations in Au+Au collisions at $\sqrt{s_{NN}}$= 19.6, 62.4, 130, and 200 GeV, Cu+Cu collisions at $\sqrt{s_{NN}}$= 62.4, 200 GeV, and p+p collisions at $\sqrt{s}$= 200 GeV using the dynamical net charge fluctuations measure $\nu_{+−,dyn}$. We observe that the dynamical fluctuations are non-zero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/$N_{ch}$ scaling, but display approximate 1/$N_{part}$ scaling. We also study the azimuthal and rapidity dependence of the net charge correlation strength and observe strong dependence on the azimuthal angular range and pseudorapidity widths integrated to measure the correlation.

本工作报道了利用动力学净电荷涨落观测量$
u_{+−,dyn}$，对$sqrt{s_{NN}}$=19.6、62.4、130及200 GeV能区金核-金核（Au+Au）碰撞、$sqrt{s_{NN}}$=62.4、200 GeV能区铜核-铜核（Cu+Cu）碰撞，以及$sqrt{s}$=200 GeV能区质子-质子（p+p）碰撞的净电荷涨落测量结果。我们观测到，所有入射能量下的动力学涨落均非零，且对束流能量呈现弱依赖关系；同时还发现其对碰撞系统尺度存在微弱依赖。通过研究净电荷涨落对碰撞中心度的依赖关系，我们发现动力学净电荷涨落违背$1/N_{ch}$标度，但近似符合$1/N_{part}$标度。此外，我们还研究了净电荷关联强度的方位角与快度依赖特性，观测到该关联强度与用于测量关联的方位角范围及伪快度积分宽度存在显著依赖。