The production of prompt ${\mathrm{\Lambda }}_c^{+}$ baryons has been measured at midrapidity in the transverse momentum interval $0<p_T<1 \text{GeV}/c$ for the first time, in $pp$ and $p$–Pb collisions at a center-of-mass energy per nucleon-nucleon collision $\sqrt{s_{NN}}=5.02\text{TeV}$. The measurement was performed in the decay channel ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0$ by applying new decay reconstruction techniques using a Kalman-Filter vertexing algorithm and adopting a machine-learning approach for the candidate selection. The $p_T$-integrated ${\mathrm{\Lambda }}_c^{+}$ production cross sections in both collision systems were determined and used along with the measured yields in Pb–Pb collisions to compute the $p_T$-integrated nuclear modification factors $R_{p\mathrm{Pb}}$ and $R_{AA}$ of ${\mathrm{\Lambda }}_c^{+}$ baryons, which are compared to model calculations that consider nuclear modification of the parton distribution functions. The ${\mathrm{\Lambda }}_c^{+}/D^0$ baryon-to-meson yield ratio is reported for $pp$ and $p$–Pb collisions. Comparisons with models that include modified hadronization processes are presented, and the implications of the results on the understanding of charm hadronization in hadronic collisions are discussed. A significant ($3.7\sigma$) modification of the mean transverse momentum of ${\mathrm{\Lambda }}_c^{+}$ baryons is seen in $p$–Pb collisions with respect to $pp$ collisions, while the $p_T$-integrated ${\mathrm{\Lambda }}_c^{+}/D^0$ yield ratio was found to be consistent between the two collision systems within the uncertainties.

• Received 9 December 2022
• Accepted 8 May 2023
• Corrected 29 June 2023

DOI:https://doi.org/10.1103/PhysRevC.107.064901

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