# Quark Matter 2018

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

## Femtoscopy with identified charged pions in $p$+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV with the ATLAS detector

15 May 2018, 17:00
2h 40m
First floor and third floor (Palazzo del Casinò)

### First floor and third floor

#### Palazzo del Casinò

Poster Collectivity in small systems

### Speaker

Brian Cole (Columbia University (US))

### Description

Hanbury Brown and Twiss (HBT) radii are measured as a function of centrality, transverse momentum, rapidity, and azimuthal angle with respect to the second-order event plane in central $p$+Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with the ATLAS detector at the LHC. A total integrated luminosity of 28 nb$^{-1}$ is sampled. The radii are presented as a function of the local density dN/dy$^\star$ and the rapidity-dependence is shown to depend directly on the density. The radii and their relative azimuthal modulation are presented as a function of the magnitude of the flow vector $|q_2|$ measured in the ATLAS calorimeters in the lead-going direction, with pseudorapidity $\eta<-2.5$. Modulations of the transverse HBT radii are observed with the same orientation as in ion--ion collisions, in which they are attributed to hydrodynamic evolution from an elliptic initial geometry. This modulation is consistent with a hydrodynamic evolution of a short-lived medium.

Content type Experiment ATLAS Presenter name already specified

### Primary authors

Barbara Krystyna Wosiek (Institute of Nuclear Physics Polish Academy of Sciences (PL)) Michael Ryan Clark (Columbia University (US))