CNF Seminar: Pierre Chatagnon

Conference Date
Conference Location

CC L102

Title: Accessing GPDs using the dilepton final state: results and perspectives with CLAS12

Speaker: Pierre Chatagnon

Abstract: Generalized Parton Distributions (GPDs) describe the correlations between the longitudinal momentum and the transverse position of the partons inside the nucleon. They are nowadays the subject of an intense effort of research, in the perspective of understanding nucleon spin and the nucleon Gravitational Form Factors (GFFs). Experimentally, the main reaction to measure GPDs have been the Deeply Virtual Compton Scattering (DVCS) reaction. In this talk, I will present complementary ways to access GPDs using the dilepton final state with the CLAS12 detector. First, I will present the first measurement of the Timelike Compton Scattering reaction (the hard photoproduction of a lepton pair), that gives access to the GPDs via the beam polarization asymmetry and angular asymmetry of the electron/positron pair. This measurement was done using data taken in 2018 by the CLAS12 detector with a 10.6 GeV electron beam impinging on a liquid-hydrogen target. I will then present the current effort to extract the near-threshold J/ψ photoproduction cross section using the same dataset. This later measurement is expected to provide direct insight on the gluons GPDs of the proton.