Examination of scaling of Hanbury-Brown--Twiss radii with charged particle multiplicity

TL;DR

This study investigates how Hanbury-Brown--Twiss radii scale with charged particle multiplicity in high-energy collisions, revealing that the scaling holds under certain conditions but breaks down across different energies and collision types.

Contribution

The paper demonstrates that HBT radii scale with charged particle multiplicity primarily when varying centrality at fixed energy, highlighting limitations of this scaling across different energies and collision systems.

Findings

Good scaling of HBT radii with multiplicity at fixed energy and varying centrality.

Scaling breaks down when comparing different energies and collision systems.

Scaling is only approximate across different energies and not valid between pp and AA collisions.

Abstract

In the light of the recent LHC data on proton-proton and lead-lead collisions we examine the question of the multiplicity scaling of HBT radii in relativistic nuclei and particle interactions. Within the UrQMD transport approach we study a large variety of system sizes at different beam energies and extract the HBT radii. In the calculation, we find a good scaling of the radii as a function of charged particle multiplicity, if the change in the multiplicity is caused by a change of centrality at the same energy. However, the scaling is only approximate when the energy, $\sqrt{s}$, is changed and breaks down when comparing pp to AA reactions.