### Speaker

### Description

Event-by-event measurement of anisotropic flow is crucial to understand the initial state conditions and particle production in heavy-ion collisions. Uranium nuclei provide a unique opportunity to study this, owing to its intrinsic prolate shape and the presence of different overlap configurations in the central collisions like body-body and tip-tip. We present the measurement of the probability distribution of event-by-event flow and multiparticle cumulants in Uranium nuclei collisions at $\sqrt{s_{NN}}$ = 193 GeV in STAR. The observed flow vector ( $\vec{Q}$ ) is smeared by statistical fluctuations and non-flow correlations. To subtract this smearing an iterative, data-driven matrix inversion method is used. The distributions of $v_2$ are observed to be Bessel-Gaussian in central and mid-central regions and deviates from Bessel-Gaussian in the peripheral region. The comparison of UU flow distributions with that of AuAu may show the manifestation of the deformed collision geometry of Uranium. From the probability distribution ( p($v_2$) ), multiparticle cumulants of $v_2$ - $v_2\{2\}$, $v_2\{4\}$ and $v_2\{6\}$ are calculated. Unfolded $v_2\{2\}$ and $v_2\{4\}$ are consistent with the results published by STAR Collaboration. The ratio of $v_2\{6\}/v_2\{4\}$ in ultra central region, is observed to be less than unity unlike AuAu where the ratio is observed to be close to unity. This observation suggests a larger deviation of p($v_2$) from Gaussian fluctuation expected in U+U collisions than in Au+Au collisions.

Collaboration | STAR |
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Preferred Track | Initial State Physics and Approach to Equilibrium |