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# Quark Matter 2017

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

## ATLAS measurements of the ridge in $pp$ and $p$+Pb collisions

Not scheduled
2h 30m
Hyatt Regency Chicago

#### Hyatt Regency Chicago

151 East Wacker Drive Chicago, Illinois, USA, 60601
Board: L14
Poster

### Speaker

Xiao Tu (Columbia University (US))

### Description

ATLAS measurements of correlations between particle pairs in relative azimuthal angle ($\Delta\phi$) and pseudorapidity separation ($\Delta\eta$) in $pp$ collisions at $\sqrt{s}$=2.76, 5.02 and 13~TeV, and in $p$+Pb collisions at $\sqrt{s_{\mathrm{NN}}}$=5.02~TeV are presented. Prior measurements have shown that in $pp$ collisions with a large multiplicity of produced particles, a long-range structure (the ridge'') develops along $\Delta\eta$ at $\Delta\phi\sim$0. However, due to the presence of the large away-side jet, the full $\Delta\phi$ dependence of the long-range correlation could not be studied. In this analysis, a template fitting procedure is implemented to determine the contributions from dijets to the correlations, using low-multiplicity
events, and to extract the genuine long-range correlation. The long-range correlations are shown to be present even in events with a small multiplicity of produced particles, implying that the long-range correlations are not unique to rare high multiplicity events. The properties of the correlation in $pp$ and $p$+Pb collisions shown to
be remarkably similar.

Preferred Track QCD in small systems ATLAS

### Primary author

Xiao Tu (Columbia University (US))

### Presentation materials

There are no materials yet.