# Quark Matter 2018

May 13 – 19, 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

## Factorization of two-particle probability distributions in Pb--Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with ALICE

May 15, 2018, 5:00 PM
2h 40m
First floor and third floor (Palazzo del Casinò)

### First floor and third floor

#### Palazzo del Casinò

Poster Collective dynamics

### Speaker

Christian Bourjau (University of Copenhagen (DK))

### Description

The flow coefficients $v_n$ are commonly extracted from multi-particle distributions where the properties of one or several particles are averaged over a large range in pseudorapidity $\eta$ or transverse momentum $p_{\text{T}}$.
Such approaches assume that the observed multi-particle distributions can be factorized into a product of single-particle distributions.
However, it is known that this condition is violated even in ideal hydrodynamics due to initial state fluctuations or the presence of non-flow.
Detailed studies of a possible violation of this factorization assumption can therefore be used to constrain the size of such fluctuations as well as to identify possible non-flow contributions.
A factorization breakdown can be measured directly in multi-particle probability distributions.
This poster presents an explicit approach to the $\eta$-dependent factorization of two-particle probability distributions within $-3.4 \leq \eta \leq 5$ in the latest $\sqrt{s_{NN}} = 5.02$ TeV Pb--Pb data measured with ALICE.
A factorizing phase-space region is identified by varying the minimal $\Delta\eta$ separation between particles; the factorization breakdown for small separations is attributed to non-flow and detector effects.
The analysis yields the well known $v_n$ coefficients as the result of the factorization process.
These flow coefficients are compared to similar results measured with the Q-cumulant method.
All findings are also compared to model calculations and previous studies at $\sqrt{s_{NN}} = 2.76$ TeV.

Centralised submission by Collaboration Presenter name already specified ALICE Experiment

### Primary author

Christian Bourjau (University of Copenhagen (DK))