Small size sources of secondaries observed in pp-collisions via Bose-Einstein correlations at the LHC ATLAS experiment

TL;DR

This paper reveals that pions in proton-proton collisions at the LHC originate from a few small sources spread over a larger interaction area, using Bose-Einstein correlations to analyze their spatial distribution.

Contribution

It introduces a novel analysis showing that pion production involves small sources distributed over a larger impact parameter space, based on Bose-Einstein correlation measurements.

Findings

Pions are produced by few small sources.

Two different spatial scales describe correlations.

Source sizes depend on particle density and transverse momentum.

Abstract

Bose-Einstein correlations in proton-proton collisions at the LHC are well descried by the formula with two different scales. It is shown for the first time that the pions are produced by few small size sources distributed over a much larger area in impact parameter space occupied by the interaction amplitude. The dependence of the two radii obtained in this procedure on the charged particle density and the mean transverse momentum of the pion/hadron in the correlated pair are discussed.