# Quark Matter 2017

Feb 5 – 11, 2017
Hyatt Regency Chicago
America/Chicago timezone

## Hydrodynamics and the Initial Shape of the Droplet in p+p and p+Pb Collisions at the LHC

Not scheduled
2h 30m
Hyatt Regency Chicago

#### Hyatt Regency Chicago

151 East Wacker Drive Chicago, Illinois, USA, 60601
Board: H08
Poster

### Speaker

Ryan Weller (University of Colorado at Boulder)

### Description

In order to test the applicability of hydrodynamics to small systems, we simulate p+p collisions at $\sqrt{s}=7\text{ TeV}$ and p+Pb collisions at $\sqrt{s}=5.02\text{ TeV}$ using the superSONIC package, which consists of AdS/CFT pre-equilibrium flow, 2+1-dimensional viscous hydrodynamics, and a hadron cascade stage. The initial conditions for hydrodynamics are generated using a Glauber-type model which replaces each nucleon in the collision by three quarks. In this model, the quarks obey a joint Gaussian distribution about a nucleon's center of mass, and each quark deposits a Gaussian-shaped cloud of entropy in the transverse plane. By varying the parameters of this model, we quantify the effect of quark substructure on observable quantities. Results from the simulations are compared with experimental data from the ATLAS, ALICE, and CMS experiments. In particular, the hydrodynamic approach reproduces the observed distribution of particle multiplicities, and further achieves a quantitatively accurate description of the flow coefficients $v_2$, $v_3$, and $v_4$ at high multiplicities. From this, we draw conclusions about the initial shape of the droplet formed in p+p and p+Pb collisions.

Preferred Track Collective Dynamics Not applicable

### Primary author

Ryan Weller (University of Colorado at Boulder)

### Co-author

Paul Romatschke (University of Colorado, Boulder)