Particle production as a function of underlying-event activity and very forward energy with ALICE

TL;DR

This paper investigates charged-particle production in proton-proton and proton-lead collisions at 5.02 TeV, analyzing underlying event activity, forward energy, and their relation to high transverse momentum triggers.

Contribution

It introduces a detailed analysis of underlying event regions and their relation to forward energy, providing new insights into particle production mechanisms at high energies.

Findings

Trans-max and trans-min regions effectively separate UE and ISR-FSR contributions.

KNO-like scaling observed in transverse regions.

Correlation between high-$p_T$ triggers and forward energy established.

Abstract

Measurements of charged-particle production in pp and p-Pb collisions at $\sqrt{s}_{\rm NN}=5.02$ TeV in the toward, away and transverse regions are discussed. These three regions are defined event by event relative to the track with the largest transverse momentum ($p_{\rm T}^{\rm trig}$). The transverse region is sensitive to the underlying event (UE), but it also includes contributions from initial- and final-state radiation (ISR-FSR). Therefore, it is further subdivided in two regions, defined according to their relative multiplicity: trans-max (the sub-transverse region with the largest multiplicity) and trans-min (the sub-transverse region with the smallest multiplicity) regions which are sensitive to UE and ISR-FSR, respectively. KNO-like scaling properties are explored in the three defined transverse regions. Finally, the relationship between $p_{\rm T}^{\rm trig}$ and the energy detected in a region close to beam rapidity (very forward energy) is reported.