First measurement of ${\mathrm{\Xi }}_{\mathrm{c}}^0$ production in $\mathbf{Pb}-\mathbf{Pb}$ collisions at $\sqrt{{\text{s}}_{\mathrm{NN}}}$ = 5.02 TeV

Abstract

The ALICE Collaboration reports the first measurement of the production of prompt ${\Xi }_{\mathrm{c}}^0$ baryons in nucleus$-$nucleus collisions by analyzing data from $\mathrm{Pb}-\mathrm{Pb}$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. The production and transverse-momentum ($p_{\mathrm{T}}$) differential spectra of ${\Xi }_{\mathrm{c}}^0$ are particularly sensitive to the hadronization process and to strangeness production in the quark--gluon plasma formed in high-energy heavy-ion collisions. The ${\Xi }_{\mathrm{c}}^0$ baryons are reconstructed at midrapidity ($|y|<0.5$) in the transverse-momentum intervals $3<p_{\mathrm{T}}<12\mathrm{GeV}/c$ and $4<p_{\mathrm{T}}<12\mathrm{GeV}/c$ in the 0$-$10\% and 30$-$50\% centrality intervals, respectively. The nuclear modification factor ($R_{\mathrm{AA}}$) reaches values up to 3 in the interval $3<p_{\mathrm{T}}<4\mathrm{GeV}/c$, which is the largest value measured so far for charm hadrons. Model predictions are compatible with the measured $R_{\mathrm{AA}}$, while, in the measured $p_{\mathrm{T}}$ intervals, they underestimate the production yield as well as the measured ${\Xi }_{\mathrm{c}}^0/{\mathrm{D}}^0$, ${\Xi }_{\mathrm{c}}^0/{\Lambda }_{\mathrm{c}}^{+}$, and ${\Xi }_{\mathrm{c}}^0/{\mathrm{D}}_{\mathrm{s}}^{+}$ yield ratios.

19 pages, 3 captioned figures, no table, authors from page 14, submitted to PRL, figures at http://alice-publications.web.cern.ch/node/13443