Production of light nuclei in small collision systems with ALICE

TL;DR

This paper discusses how the production of light nuclei in small collision systems at the LHC depends mainly on event multiplicity, with measurements supporting statistical and coalescence models.

Contribution

It provides new experimental data on light nuclei production in small systems, including in jets and the underlying event, and compares these results with theoretical models.

Findings

Light nuclei production correlates with event multiplicity.

Deuteron-to-proton and helium-3-to-proton ratios evolve with multiplicity.

Production in jets and underlying events supports coalescence and statistical models.

Abstract

The energy densities reached in high-energy hadronic collisions at the LHC allow significant production of light (anti)nuclei. Their production yields have been measured as a function of $p_{\rm T}$ and charged-particle multiplicity in different collision systems and at different center-of-mass energies by ALICE. One of the most interesting results obtained from such a large variety of experimental data is that the dominant production mechanism of light (anti)nuclei seems to depend solely on the event charged-particle multiplicity. Evidence for this comes from the continuous evolution of the deuteron-to-proton and $^3$He-to-proton ratios with the event multiplicity across different collision systems and energies. The characterization of the light nuclei production mechanism is complemented by measurements of their production yields in jets and in the underlying event. In this paper, recent results on light nuclei production in small collision systems are shown and discussed in the context of the statistical hadronization and coalescence models. In addition, recent results on the deuteron production in jets and new preliminary results on its production in the underlying event measured in pp collisions at $\sqrt{s} = $ 13 TeV are discussed.