# Quark Matter 2017

5-11 February 2017
Hyatt Regency Chicago
America/Chicago timezone

## New insights of multi-particle azimuthal correlations via differential studies in high-multiplicity pPb collisions with CMS

7 Feb 2017, 08:50
20m
Regency B

### Regency B

Oral QCD in small systems

### Speaker

Maxime Guilbaud (Rice University (US))

### Description

The formation of a QGP in heavy ion collisions and the hydrodynamic expansion of the created medium are well established and reasonably well understood. This state of nuclear matter was not expected to be found in reactions involving smaller systems, such as the pA and pp collisions. Nevertheless, a wealth of experimental evidence in recent years has suggested the presence of collective phenomena and a possible QGP medium being formed also in high-multiplicity pPb collisions. A detailed investigation is needed to establish the cause of the observed collective behavior and to determine if, indeed, a QGP medium is being created or if another mechanism is responsible. Final results of differential $v_{n}$ harmonics in pPb collisions as a function of transverse momentum and pseudorapidity obtained using scalar product, multi-particle cumulant and Lee-Yang Zeros methods are presented in various multiplicity classes. The effect of event plane decorrelations on the observed $\eta$ dependence of $v_{n}$ is studied in detail. Furthermore, new measurements of correlation between $v_{2}$ and $v_{3}$ ($v_{4}$) harmonics are performed using the technique of symmetric cumulants to gain more insight to the initial state and possible medium response of the pPb system. The results shown in this talk relate to our understanding of the origin of azimuthal correlations in high-multiplicity pPb events and shed light on a potential QGP formation in small system collisions.

Collaboration CMS QCD in small systems

### Primary author

Maxime Guilbaud (Rice University (US))