Relatore
Descrizione
Protons and neutrons are the building blocks of atomic nuclei. Understanding their internal structure is crucial for addressing fundamental questions in physics and interpreting phenomena, such as the high energy scattering processes currently under study at the LHC.
Despite significant progress throughout the years, many fundamental questions remain unanswered: where does the mass of the nucleons originate? What determines their spin? How are partons distributed within nucleons?
Our analysis focuses on accessing the 3-dimensional structure of the nucleons via transverse-momentum-dependent distributions (TMDs), which describe the transverse motion of the partons, as well as the correlation between their spins and momenta.
In particular, we investigate gluon TMDs, which remain less understood than their quark counterparts, through the production of heavy quark-antiquark bound states (quarkonia) in proton-proton collisions, within the framework of TMD factorization combined with non-relativistic QCD.
Our analysis focuses on quarkonium states with even charge conjugation, where the color-singlet production mechanism dominates at small transverse momenta. We demonstrate how linearly polarized gluons inside unpolarized, longitudinally, and transversely polarized protons contribute to the cross sections for scalar and pseudoscalar quarkonia.
We will show the results of single and double spin asymmetries, enabling direct extraction of gluon TMDs, analogous to quark TMD studies in Drell-Yan processes. Using Gaussian models for gluon TMD, we provide numerical predictions for transverse single-spin asymmetries, which could be tested in the proposed LHCSpin fixed-target experiment.
