Seminarium Fizyki Wielkich Energii

In this talk, I will start by generally introducing Lattice QCD, the non-perturbative formulation of QCD on a Euclidean lattice. Then, I will show what Lattice QCD can tell us about the internal dynamics of the nucleon. In particular, I will present a state-of-the-art computation of unpolarized, helicity and transversity parton distribution functions (PDFs), calculated using the so-called quasi-PDF approach introduced by Xiangdong Ji in 2013 and intensively developed thereafter. I will show the steps needed to get from the lattice computation of bare matrix elements, i.e. renormalization, matching and target mass corrections, to arrive at the final light-cone PDFs. For the latter, we find a similar behavior between the lattice and phenomenologically extracted data. This presents a major success for the emerging field of direct calculations of quark distributions using Lattice QCD. At the same time, it is clear that a careful investigation of lattice systematic effects is needed to arrive at the final reliable result.