Charm cross section and fragmentation fractions in pp collisions with ALICE (12'+3')

Abstract

In this contribution, the latest Λ + c , Ξ 0c and the first Ξ + c , Σ 0 , ++ c and Ω 0c baryon measurements performed with the ALICE detector at midrapidity in proton–proton collisions at √ 𝑠 = 5 . 02 TeV and 13 TeV at the LHC are presented. Recent measurements of baryon-to-meson cross-section ratios at midrapidity show significantly higher results than in e + e − and ep collisions, suggesting that the fragmentation of charm is not universal across different collision systems. Thus, measurements of charm-baryon production are crucial to study the charm-quark hadronisation in pp collisions and the possible difference with respect to e + e − and ep collisions. In addition, the baryon-production measurements were essential for the measurement of the c¯c production cross section performed by ALICE at midrapidity in pp collisions and also presented in this contribution. Furthermore, the new preliminary measurement of the Λ + c /D 0 ratio in 0 ≤ 𝑝 T < 1 GeV / 𝑐 in p–Pb collisions will be discussed. The measurement of charm baryons in proton–nucleus collisions provides important information about Cold Nuclear Matter (CNM) effects. It also helps to understand how the possible presence of collective effects could modify the production of heavy-flavour hadrons and to interpret the similarities observed among pp, proton–nucleus and nucleus–nucleus systems.