Speaker
Description
We present new differential measurements of charge separation relative to the second- ($\Psi_2$), third- ($\Psi_3$) and fourth-order ($\Psi_4$) event planes for Au+Au collisions at $\sqrt{s_{NN}}$= 200, 39, 27 and 19.6~GeV, U+U at $\sqrt{s_{NN}}$= 193 GeV and Cu+Au, Cu+Cu, d+Au and p+Au at $\sqrt{s_{NN}}$=200 GeV. The measurements are performed with a charge-sensitive correlator $R(\Delta S)$ [1] and the three-particle mixed harmonic correlator $\mathrm{C_{m,n,m+n} = \left< cos(m\phi_1 + n\phi_2 -(m+n)\phi_3)\right>}$ [2]. These are expected to give different responses to the CME-driven charge separation and non-CME background correlations. The $R(\Delta S)$ measurements are found to be flat relative to $\Psi_3$ in all systems and $\Psi_2$ in p(d)+Au systems, consistent with the expectation of random $\vec{B}$-field orientations relative to these event planes. In contrast, the heavy-ion measurements relative to $\Psi_2$ show concave-shaped $R(\Delta S)$ distributions, which is consistent with the presence of CME-driven charge separation characterized by an out-of-plane Fourier dipole coefficient $a_1$. We will present and discuss $R(\Delta S)$ and $\mathrm{C_{m,n,m+n}}$ measurements for a broad range of transverse momenta, pseudorapidity, and centrality intervals and compare it with model predictions [1]. The implication of these measurements for the upcoming isobar collisions at RHIC will also be discussed.
References
[1] N. Magdy, S. Shi, J. Liao, N. Ajitanand, and R. A. Lacey, arXiv:1710.01717.
[2] L. Adamczyk et al. (STAR Collaboration), arXiv:1701.06496.
| Content type | Experiment |
|---|---|
| Collaboration | STAR |
| Centralised submission by Collaboration | Presenter name already specified |
