Charged particle correlations with ATLAS

Correlations between charged particles provide an important insight about hadronization processes. Results on Bose-Einstein two-particle correlations using ATLAS data from LHC proton-proton collisions at the center-of-mass energy of 13 TeV are presented. Data were collected in a special low-luminosity configuration with a minimum-bias trigger and a high-multiplicity track trigger, accumulating integrated luminosities of 151 $\mu\mathrm{b}^{-1}$ and 8.4 $\mathrm{nb}^{-1}$, respectively. The BEC are measured for pairs of like-sign charged particles, each with $|\eta|$ < 2.5 and for two kinematic ranges: $p_\mathrm{T}$ > 100 MeV and $p_\mathrm{T}$ > 500 MeV. The BEC parameters, characterizing the source radius and particle correlation strength, are investigated as functions of charged-particle multiplicity (up to 300) and average transverse momentum of the pair (up to 1.5 GeV). The double-differential dependence on charged-particle multiplicity and average transverse momentum of the pair is also studied. The BEC radius is found to be independent of the charged-particle multiplicity for high multiplicity (above 100), confirming a previous observation at lower energy. This saturation occurs independently of the transverse momentum of the pair.