Parton Distribution Functions (PDFs) give the probability to find partons (quarks and gluons) in a hadron as a function of the fraction x of the proton's momentum carried by the parton. PDFs are obtained by fitting observables to experimental data, and they cannot be calculated using perturbative QCD. After showing the latest developments in the fitting methodology, the talk will cover the most recent PDF determinations, with a particular emphasis on the results of the ATLASpdf21 fit, the first 'global' PDF fit from an experimental collaboration. Finally we will discuss the importance of the correct and consistent treatment of theory and measurements for the precise determination of PDF.
Francesco Giuli is an ATLAS experimental physicist. Currently he is a Senior Research Fellow at CERN. Previously, he held a postdoctoral position at the University of Roma Tor Vergata. He obtained his PhD at the University of Oxford. His research interests focus on precision measurements which can advance our knowledge of Parton Distribution Functions, as well as on the determination of fundamental SM parameters, such as the strong coupling constant and the W mass.
Juan Cruz Martinez is a senior fellow in the Theory department at CERN. Prior to that he held a postdoctoral position at the University of Milan in the group of Prof. Stefano Forte. He obtained his PhD at the University of Durham working on fixed-order calculations. He is currently a member of the NNPDF collaboration where he works on the application of machine learning techniques to the precise determinations of parton distribution functions. His main research focus is on the usage of technological improvements (hardware accelerators, machine learning) to particle physics phenomenology.