Speaker
Description
Precise measurements of charm-hadron production in proton--proton (pp) collisions at the LHC are fundamental to test perturbative QCD-based calculations and to investigate the charm-quark hadronization. Recent measurements in pp collisions show baryon-to-meson ratios significantly larger than those in $\mathrm{e^+e^-}$ collisions, challenging the validity of theoretical calculations based on the factorization approach and assuming universal fragmentation functions across collision systems.
Recent advances in charm-meson spectroscopy have led to the discovery of several excited charm-strange states, whose production yields in hadronic collisions are unmeasured. Quantifying these yields provides valuable insights into charm-quark hadronization, given the significant contribution to the ground-state charm-hadron yields from their decays.
At LHC energies, Multi Parton Interactions (MPI), where multiple hard-parton scatterings occur in a single collision, play a significant role. Among these, Double Parton Scattering (DPS) represents the simplest case, where two independent scatterings take place simultaneously. The study of the production of charm-hadron pairs in the same collisions allows us to investigate the double charm production via single (SPS) and double parton scattering (DPS). In particular, like-sign meson pairs are expected to be predominantly produced by DPS processes, while opposite-sign pairs are more likely to be created via SPS.
This contribution presents various measurements exploiting the large data sample of pp collisions at $\sqrt{s} = 13.6$ TeV collected from the start of LHC Run 3. In particular, the production yield ratios of $\mathrm{D_s}^+$ to $\mathrm{D}^+$ mesons as a function of charged-particle multiplicity are shown and compared to state-of-the-art model predictions. New production measurements of the orbitally excited charm-strange mesons $\mathrm{D_{s1}}(2536)^+$ and $\mathrm{D_{s2}}^{*}(2573)^+$ are also reported. In addition, the first measurements of the production of charm-baryons $\Lambda_\mathrm{c}^+$, $\Sigma_\mathrm{c}^{0,+,++}(2455)$, $\Sigma_\mathrm{c}^{0,+,++}(2520)$ are presented and compared with model predictions.
Finally, the production cross section of like-sign and opposite-sign $\mathrm{D}^0$ meson pairs is measured and compared to the single $\mathrm{D}^0$-meson production cross section.
