# Initial Stages 2021

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

## Linear and non-linear flow coefficients from transport theory

Jan 13, 2021, 4:30 PM
20m
Andrea’s room 1 (vDLCC)

### Andrea’s room 1

#### vDLCC

oral Collective dynamics from small to large systems

### Speaker

Urs Wiedemann (CERN)

### Description

The observation of fluid-like behavior in nucleus-nucleus (AA), proton-nucleus (pA) and high-multiplicity proton-proton (pp) collisions motivates systematic studies of how different measurements approach their fluid-dynamic limit. We have developed numerical methods to solve the ultra-relativistic Boltzmann equation for systems of arbitrary size and transverse geometry. Here, we apply these techniques for the first time to the study of azimuthal flow coefficients $v_n$ including non-linear mode-mode coupling and to an initial condition with realistic event-by-event fluctuations. We show how both linear and non-linear response coefficients extracted from $v_n$ develop as a function of opacity
from free streaming to perfect fluidity. We note in particular that away from the fluid-dynamic limit, the signal strength of linear and non-linear response coefficients does not reduce uniformly, but that their hierarchy and relative size shows characteristic differences.

### Primary authors

Bin Wu (CERN) Eero Aleksi Kurkela (CERN) Seyed Farid Taghavi (Technische Universitaet Muenchen (DE)) Urs Wiedemann (CERN)

### Presentation materials

 IS21wiedemann.pdf Recording