Disentangling flow and signals of Chiral Magnetic Effect in U+U, Au+Au and p+Au collisions

Understand

We present STAR measurements of the charge-dependent three-particle correlator $\gamma^{a,b}=\langle \cos(\phi_1^{a}+\phi_2^{b}-2\phi_3)\rangle/v_{2}\{2\}$ and elliptic flow $v_{2}\{2\}$ in U+U, Au+Au and p+Au collisions at RHIC.

• The difference $\Delta \gamma = \gamma(\rm{opposite\!-\!sign})\!-\!\gamma(\rm{same\!-\!sign})$ measures charge separation across the reaction plane, a predicted signal of the Chiral Magnetic Effect (CME).
• Although charge separation has been observed, it has been argued that the measured separation can also be explained by elliptic flow related backgrounds.
• In order to separate the two effects, we perform measurements of the $\gamma$-correlator where background expectations differ from magnetic field driven effects.