In this talk, I will present an overview of heavy ion collisions. In particular, I will introduce the main phenomena in these collisions, and discuss them from the point of view of QCD, in order to highlight some of the possible approaches to tackle situations where collective phenomena play a crucial role.
Nearly ten years ago, Kang, Ma, Qiu, and Sterman derived an evolution equation for a heavy-quark pair fragmenting into a quarkonium. In this study we explore the consequence of this evolution for the color-evaporation model, focusing on $J/\psi$ transverse-momentum distributions in proton-proton collisions. In particular, I will show that it brings NLO calculations in agreement with data....
Quarkonia are perfect laboratories to study the interplay between perturbative and nonperturbative QCD, due to the different momentum scales it provides. I am going to focus on the production of quarkonia through the fragmentation of a gluon, one of the possible mechanisms to quarkonia production. I am going to talk about the factorization of the TMD in terms of the short-distance coefficients...
We calculate the production of polarized $J/\psi$ to probe the transverse momentum dependent (TMD) quark and gluon PDFs in the proton. Within the TMD framework we calculate the 18 leading order fragmentation functions for light quarks fragmenting to a $J/\psi$, considering all possible parton and hadron polarizations. We also calculate the production of $J/\psi$ from photon-gluon fusion within...
We present an updated analysis of Belle data for the transverse $\Lambda$ polarization in $e^+e^−$ annihilation processes within a TMD factorization approach. Special attention to $SU(2)$ isospin symmetry and charm quark contribution will be paid, both concerning the description of the experimental data and the extraction of the polarizing fragmentation functions.
Predictions for SIDIS...
