Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

TL;DR

This study measures how particle yields in jet-like correlations are modified in lead-lead collisions compared to proton-proton collisions at high energies, revealing suppression on the away-side and slight enhancement on the near-side.

Contribution

It provides the first detailed measurement of charged particle yield modifications in azimuthal di-hadron correlations at LHC energies in Pb-Pb collisions.

Findings

Away-side yield drops to 60% of pp in central collisions.

Near-side yield shows a 20-30% enhancement.

Results indicate significant jet quenching effects.

Abstract

The yield of charged particles associated with high-$p_{\rm T}$ trigger particles ($8 < p_{\rm T} < 15$ GeV/$c$) is measured with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jet-like correlation peaks in azimuthal di-hadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta $p_{\rm T}> 3$ GeV/$c$ on the away-side drops to about 60% of that observed in pp collisions, while on the near-side a moderate enhancement of 20-30% is found.