pANUCSTR · Study of the distribution of gluons and quarks inside the nucleon through ultra-peripheral collisions

The proposed research will provide a deeper understanding of the internal structure of the nucleon by studying ultra-peripheral collisions (UPCs) of protons and ions using data collected by the LHCb experiment at the Large Hadron Collider at CERN. The structure will be probed by measuring the cross sections of (i) time-like Compton scattering, (ii) exclusive diffractive production of J/ψ mesons, (iii) pairs of mesons containing charm or bottom quarks and (iv) dijet production in proton-lead UPCs. The first two processes probe gluon and quark generalized parton distributions, which describe the distribution of quarks and gluons inside the nucleon or heavy ion as a function of their longitudinal momentum fraction and their transverse position. The last two processes offer access to Wigner distributions, which in addition are sensitive to transverse momentum. The processes are also sensitive to saturation phenomena.