The unambiguous observation of a chiral magnetic effect (CME)–driven charge separation is the core aim of the isobar program at the Relativistic Heavy Ion Collider (RHIC), consisting of ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$ and ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. We quantify the role of the spatial distributions of the nucleons in the isobars on both eccentricity and magnetic field strength within a relativistic hadronic transport approach (simulating many accelerated strongly interacting hadrons, SMASH). In particular, we introduce isospin-dependent nucleon-nucleon spatial correlations in the geometric description of both nuclei, deformation for ${}_{44}{}^{96}\mathrm{Ru}$ and the so-called neutron skin effect for the neutron-rich isobar, i.e., ${}_{40}{}^{96}\mathrm{Zr}$. The main result of this study is a reduction of the magnetic field strength difference between ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ and ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$ by a factor of 2, from $10\%$ to $5\%$ in peripheral collisions when the neutron-skin effect is included. Further, we find an increase of the eccentricity ratio between the isobars by up to 10% in ultracentral collisions as due to the deformation of ${}_{44}{}^{96}\mathrm{Ru}$ while neither the neutron skin effect nor the nucleon-nucleon correlations result into a significant modification of this observable with respect to the traditional Woods-Saxon modeling. Our results suggest a significantly smaller CME signal to background ratio for the experimental charge separation measurement in peripheral collisions with the isobar systems than previously expected.

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BNL相对论重离子对撞机提供的能量下，中子皮效应对核等压线碰撞的影响

相对论重离子对撞机（RHIC）的等压线计划的核心目标是对手性磁效应（CME）驱动的电荷分离进行清晰观察。 ${}_{40}{}^{96}锆+{}_{40}{}^{96}锆$ 和 ${}_{44}{}^{96}茹+{}_{44}{}^{96}茹$ 发生碰撞 $\sqrt{s_{\mathrm{神经网络}}}=200$GeV。我们在相对论性强子运输方法（模拟许多加速的强相互作用强子，SMASH）中量化了等压线中核子空间分布对偏心率和磁场强度的作用。特别是，我们在两个核的几何描述中引入了等位旋依赖性核子-核子空间相关性，${}_{44}{}^{96}茹$ 所谓的中子趋肤效应就是富中子的等压线，即 ${}_{40}{}^{96}锆$。这项研究的主要结果是减小了磁场强度之间的差异${}_{44}{}^{96}茹+{}_{44}{}^{96}茹$ 和 ${}_{40}{}^{96}锆+{}_{40}{}^{96}锆$ 从2倍 $10％$ 至 $5％$包括中子皮肤效应在内的外围碰撞中 此外，我们发现在超中心碰撞中，等压线之间的偏心率增加了多达10％，这是由于杆的变形引起的。${}_{44}{}^{96}茹$相对于传统的Woods-Saxon模型，中子集肤效应和核子-核子相关性均未导致这种可观察到的显着变化。我们的结果表明，在与等压线系统进行外围碰撞时进行实验性电荷分离测量的CME信噪比要比以前预期的要小得多。