Measurement of long-range correlations in $pp$ collisions characterized by presence of a Z boson with ATLAS
A. Trzupek* on behalf of the ATLAS Collaboration
Pre-published on:
January 11, 2019
Published on:
April 24, 2019
Abstract
Measurements of azimuthal correlations between two particles separated in pseudorapidity have shown striking similarities between results obtained in $pp$, $p$+A and A+A collision systems. In $pp$ collisions, unlike in $p$+A and A+A, the strength of the correlations, quantified by the anisotropy parameter $v_2$, shows little dependence on the observed charged-particle multiplicity. Recent theoretical models suggest that this can result from an intrinsically weaker correlation between the charged-particle multiplicity and the impact parameter of the $pp$ collision. An independent handle on the impact parameter can be obtained by requiring the presence of a hard-scattering process in the collision. In this report the measurement of two-particle correlations in $pp$ collisions containing a $Z$ boson identified in dimuon decay channel is presented. The analysis uses ATLAS data recorded with nominal $pp$ luminosity, with a high pileup. A novel procedure was developed to correct the two-particle correlation function for the contribution of tracks arising from pileup . The multiplicity dependence of the charged-particle $v_2$ measured in $Z$-tagged events at the energy $\sqrt{s}$ = 8 TeV is compared to the $v_2$ measured in inclusive collisions. They are found to be of a similar magnitude.
DOI: https://doi.org/10.22323/1.345.0109
How to cite
Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating
very compact bibliographies which can be beneficial to authors and
readers, and in "proceeding" format
which is more detailed and complete.