Recent results on hard and rare probes from ALICE

TL;DR

This paper reviews recent ALICE results on hard and rare probes in high-energy collisions, focusing on heavy-flavor hadrons and quarkonium production to understand QGP properties and QCD processes.

Contribution

It presents new measurements of heavy-flavour baryons and quarkonium production as functions of multiplicity, providing insights into charm fragmentation and production mechanisms.

Findings

Heavy-flavour baryon measurements shed light on charm fragmentation.

Charmonium production varies with event multiplicity, indicating interplay with soft processes.

Cross sections constrained by Monte Carlo fits to dielectron continuum.

Abstract

In high-energy hadronic collisions, hard parton scatterings with large momentum transfers are prerequisites for the formation of hard and rare probes. In heavy-ion collisions, these probes---final state particles related to the early hard-parton scatterings---serve as a powerful tool to explore the whole evolution of the medium including the quark--gluon plasma (QGP) stage. Hard probes in proton-proton (pp) collisions test perturbative quantum chromodynamics (pQCD) processes and hadronization, and provide a reference for the nuclear collision systems. High-multiplicity pp collisions provide a bridge to heavy-ion collisions, due to their large event activity. Heavy-flavor hadrons containing at least one charm or beauty quark belong to the hard and rare probes. Recently, ALICE has measured a broad palette of heavy-flavour baryons allowing to shed more light on charm fragmentation. Measurements of charmonium production as a function of the event multiplicity can provide insight into the interplay between charmonium-production processes and soft processes driving the multiplicity. ALICE has investigated the multiplicity dependence of J/$\psi$ production at midrapidity and the ratio of $\psi \rm (2S)$ to J/$\psi$ yields at forward rapidity. The charm and beauty cross sections can be constrained by fits of Monte-Carlo generators to the measured dielectron continuum.