Collision-system dependence of charge separation relative to the second- and third-order event planes; Implications for the Chiral Magnetic Effect in STAR

4 Nov 2019, 17:40
20m
Wanda Han Show Theatre & Wanda Reign Wuhan Hotel

Wanda Han Show Theatre & Wanda Reign Wuhan Hotel

Poster Presentation Chirality, vorticity and spin polarization Poster Session

Speaker

Niseem Abdelrahman (University of Illinois at Chicago)

Description

Validation of the Chiral Magnetic Effect (CME) in the quark-gluon plasma (QGP) produced in heavy-ion collisions can provide key insights into anomalous transport in QGP and the connections between chiral symmetry restoration, axial anomaly and gluonic topology. Recently, a charge-sensitive correlator, $\mathrm{R_{\Psi_m}(\Delta S)}$ [1], designed to discern between background- and CME-driven charge separation was used to carry out a detailed set of charge separation measurements, relative to both the $2^{\mathrm{nd}}$- ($\Psi_2$) and $3^{\mathrm{rd}}$-order ($\Psi_3$) event planes for several collision systems (A+A(B)). The measurements indicate nearly flat to convex $\mathrm{R_{\Psi_m}(\Delta S)}$ distributions for the measurements relative to $\Psi_3$ and those relative to $\Psi_2$ for the p(d)+Au systems, consistent with the essentially random $\vec{B}$-field orientations for these measurements. By contrast, the A+A measurements relative to $\Psi_2$ show concave-shaped $\mathrm{R_{\Psi_2}(\Delta S)}$ distributions suggestive of a CME-driven charge separation. Results for U+U collisions at $\sqrt{s_{NN}}$= 193 GeV and p(d)+Au, Cu+Au, Cu+Cu and Au+Au collisions at $\sqrt{s_{NN}}=$ 200 GeV will be presented and discussed in this poster.

[1] N. Magdy, et al., Phys. Rev. C 97 (2018) 061901.

Primary author

Niseem Abdelrahman (University of Illinois at Chicago)

Presentation Materials