Two-particle Bose-Einstein correlations in $pp$ collisions at $\mathbf {\sqrt{s} =}$ 0.9 and 7 TeV measured with the ATLAS detector

TL;DR

This study measures Bose-Einstein correlations in proton-proton collisions at 0.9 and 7 TeV using the ATLAS detector, revealing how correlation parameters depend on multiplicity and transverse momentum, with a saturation effect observed at high multiplicities.

Contribution

First measurement of BEC parameters in pp collisions at these energies, analyzing their dependence on multiplicity and transverse momentum with high-statistics data.

Findings

Correlation source size saturates at high multiplicity.

BEC parameters vary with pair transverse momentum.

Evidence of multiplicity dependence in correlation strength.

Abstract

The paper presents studies of Bose-Einstein Correlations (BEC) for pairs of like-sign charged particles measured in the kinematic range $p_{\rm T}>$ 100 MeV and $|\eta|<$ 2.5 in proton--proton collisions at centre-of-mass energies of 0.9 and 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. The integrated luminosities are approximately 7 $\mu$b$^{-1}$, 190 $\mu$b$^{-1}$ and 12.4 nb$^{-1}$ for 0.9 TeV, 7 TeV minimum-bias and 7 TeV high-multiplicity data samples, respectively. The multiplicity dependence of the BEC parameters characterizing the correlation strength and the correlation source size are investigated for charged-particle multiplicities of up to 240. A saturation effect in the multiplicity dependence of the correlation source size is observed using the high-multiplicity 7 TeV data sample. The dependence of the BEC parameters on the average transverse momentum of the particle pair is also investigated.