Deuteron coalescence probability in jets in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

TL;DR

This study measures deuteron and antiproton production in p-Pb collisions at 5.02 TeV, revealing an enhancement of the coalescence parameter in jets compared to the underlying event, and compares results with theoretical models and previous pp data.

Contribution

First measurement of deuteron coalescence in jets in p-Pb collisions, providing new insights into particle production mechanisms at high energies.

Findings

Deuteron coalescence parameter $B_2$ is enhanced in jets compared to the underlying event.

The enhancement in p-Pb exceeds that observed in pp collisions.

PYTHIA 8.314 with Angantyr model qualitatively reproduces the observed enhancement.

Abstract

This article presents the first measurement of the (anti)deuteron and antiproton transverse-momentum distributions, the deuteron coalescence parameter, and the ratio between the yields of deuteron and proton in and out of jets in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. Three regions are used to study the jet-correlated production: Toward, Away, and Transverse to the jet axis, which direction is approximated by the leading particle in the event with $p_{\rm T}^{\rm lead} > 5$ GeV/$c$. The jet contribution is obtained from the Toward region by subtracting the underlying event, which dominates the Transverse region. In p-Pb collisions, an enhancement of the coalescence parameter $B_{\rm 2}$ is observed in jets compared to the underlying event. The enhancement is larger than the one observed in a similar analysis already in pp collisions. The results are compared with predictions from PYTHIA 8.314 using the Angantyr model with a deuteron production model based on ordinary nuclear reactions. The model is able to qualitatively reproduce the large enhancement of the coalescence parameter in jets with respect to the out-of-jets one. The results are further compared in detail with similar ones from previous studies for pp collisions at $\sqrt{s} = 13$ TeV.