# Initial Stages 2021

Jan 10 – 15, 2021
Weizmann Institute of Science
Asia/Jerusalem timezone
See you at IS2023 in Copenhagen in June 2023

## Polarization in heavy-ion collisions via local initial energy deposition

Jan 13, 2021, 7:45 PM
1h 30m
Patio (vDLCC)

### Patio

#### vDLCC

bullet talk (poster) The initial stages of heavy-ion collisions

### Speaker

Willian M. Serenone (Universidade Estadual de Campinas)

### Description

In the recent past the STAR collaboration reported the measurement of Λ hyperon in non-central AuAu collisions. The origin of this polarization was successfully modeled as the vorticity present in the QGP fluid due to the non-zero angular momentum in non-central collisions. Other phenomena may generate vorticity in a fluid. A fast parton crossing the QGP transfers momentum and energy to it and will introduce a gradient in velocity, which will lead to vorticity generation. In our work, we model such energy-momentum deposition as a spot of high energy and high velocity a few cells wide. We embed it in a smooth initial condition based on central PbPb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV and evolve it using (3+1)D hydrodynamic using MUSIC. We show that our initial condition generates a vortex ring in the hydrodynamic evolution, with noticeable effects on the spin polarization of Λ hyperons. We present a study showing the dependance of this effect with shear viscosity and parameters of the energy-momentum deposition.

### Primary authors

Willian M. Serenone (Universidade Estadual de Campinas) David Dobrigkeit Chinellato (University of Campinas UNICAMP (BR)) Mike Lisa (Ohio State University (US)) Chun Shen (Wayne State University) Jun Takahashi (University of Campinas UNICAMP (BR)) Giorgio Torrieri (IFGW, Unicamp)

### Presentation materials

 Bullet_Talk_Willian_M_Serenone.pdf IS_Presentation.mp4