# Quark Matter 2019 - the XXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions

3-9 November 2019
Wanda Reign Wuhan Hotel
Asia/Shanghai timezone

## Ultracentral Collisions of Small and Deformed Systems at RHIC

5 Nov 2019, 12:00
20m
Ball Room 2 (Wanda Reign Wuhan Hotel)

### Ball Room 2

#### Wanda Reign Wuhan Hotel

Oral Presentation Small systems

### Speaker

Douglas Wertepny (Ben Gurion University of the Negev)

### Description

We study a range of collision systems involving deformed ions and compare the elliptic and triangular flow harmonics produced in a hydrodynamics scenario versus a color glass condensate (CGC) scenario. For the hydrodynamics scenario, we generate initial conditions using TRENTO and work within a linear response approximation to obtain the final flow harmonics. For the CGC scenario, we use the explicit calculation of two-gluon correlations taken in the high-$p_T$ (semi)dilute-(semi)dilute'' regime to express the flow harmonics in terms of the density profile of the collision. We consider ultracentral collisions of deformed ions as a testbed for these comparisons because the difference between tip-on-tip and side-on-side collisions modifies the multiplicity dependence in both scenarios, even at zero impact parameter. We find significant qualitative differences in the multiplicity dependence obtained in the initial conditions+hydrodynamics scenario and the CGC scenario, allowing these collisions of deformed ions to be used as a powerful discriminator between models. We also find that sub-nucleonic fluctuations have a systematic effect on the elliptic and triangular flow harmonics which are most discriminating in $0-1\%$ ultracentral symmetric collisions of small deformed ions and in $0-10\%$ $\mathrm{d} {}^{197}\mathrm{Au}$ collisions. The collision systems we consider are ${}^{238}\mathrm{U} {}^{238}\mathrm{U}$, $\mathrm{d} {}^{197}\mathrm{Au}$, ${}^{9}\mathrm{Be} {}^{197}\mathrm{Au}$, ${}^{9}\mathrm{Be} {}^{9}\mathrm{Be}$, ${}^{3}\mathrm{He} {}^{3}\mathrm{He}$, and ${}^{3}\mathrm{He} {}^{197}\mathrm{Au}$.

### Primary authors

Douglas Wertepny (Ben Gurion University of the Negev) Jacquelyn Noronha-Hostler (Rutgers University) Noah Paladino (Rutgers State Univ. of New Jersey (US)) Matthew Sievert (Los Alamos National Laboratory) Skandaprasad Rao (Rutgers University)