Measurement of the production cross section of prompt \(\Xi ^0_{\textrm{c}}\) baryons in p–Pb collisions at \(\sqrt{s_{{\textrm{NN}}}}=5.02\) TeV

Abstract

The transverse momentum (\(p_{\textrm{T}}\)) differential production cross section of the promptly produced charm-strange baryon \(\mathrm {\Xi _{c}^{0}}\) (and its charge conjugate \(\overline{\mathrm {\Xi _{c}^{0}}}\)) is measured at midrapidity via its hadronic decay into \(\mathrm{\pi ^{+}}\Xi ^{-}\) in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision \(\sqrt{s_{\textrm{NN}}}~=~5.02\) TeV with the ALICE detector at the LHC. The \(\mathrm {\Xi _{c}^{0}}\) nuclear modification factor (\(R_{\textrm{pPb}}\)), calculated from the cross sections in pp and p–Pb collisions, is presented and compared with the \(R_{\textrm{pPb}}\) of \(\mathrm {\Lambda _{c}^{+}}\) baryons. The ratios between the \(p_{\textrm{T}}\)-differential production cross section of \(\mathrm {\Xi _{c}^{0}}\) baryons and those of \(\mathrm {D^0}\) mesons and \(\mathrm {\Lambda _{c}^{+}}\) baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt \(\Xi ^0_\textrm{c}\) baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p–Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model that includes string formation beyond leading-colour approximation or in which hadronisation is implemented via quark coalescence. The \(p_{\textrm{T}}\)-integrated cross section of prompt \(\Xi ^0_\textrm{c}\)-baryon production at midrapidity extrapolated down to \(p_{\textrm{T}}\) = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p–Pb collisions at midrapidity.