Measurement of ${}_{\Lambda}^{3}\mathrm{H}$ production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

TL;DR

This paper reports the first measurement of $_{\Lambda}^{3} ext{H}$ and anti-hypertriton production in Pb-Pb collisions at 5.02 TeV, comparing results with models to understand their formation mechanisms.

Contribution

It provides the first differential production measurements of $_{\Lambda}^{3} ext{H}$ in heavy-ion collisions and compares the data to theoretical models, favoring the coalescence model.

Findings

$_{\Lambda}^{3} ext{H}$ production consistent with other nuclei in freeze-out surface

Data favors coalescence model over statistical hadronisation

Yields measured as a function of transverse momentum and centrality

Abstract

The first measurement of $_{\Lambda}^{3}\mathrm{H}$ and $^3_ {\overline{\Lambda}}\overline{\mathrm{H}}$ differential production with respect to transverse momentum and centrality in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$~TeV is presented. The $_{\Lambda}^{3}\mathrm{H}$ has been reconstructed via its two-charged-body decay channel, i.e., $_{\Lambda}^{3}\mathrm{H} \rightarrow {}^{3}\mathrm{He} + \pi^{-}$. A Blast-Wave model fit of the $p_{\rm T}$-differential spectra of all nuclear species measured by the ALICE collaboration suggests that the $_{\Lambda}^{3}\mathrm{H}$ kinetic freeze-out surface is consistent with that of other nuclei. The ratio between the integrated yields of $_{\Lambda}^{3}\mathrm{H}$ and $^3\mathrm{He}$ is compared to predictions from the statistical hadronisation model and the coalescence model, with the latter being favoured by the presented measurements.