Computerised Tomography of Nucleons – CompToN

One of the golden objectives of the hadron physics community is to access the 3D tomography of the nucleon in terms of quarks and gluons. The latter is encoded in generalised parton distributions (GPDs) which describe deep exclusive processes. After two decades of pioneering measurements, the community has entered the precision era with the publication of a wealth of experimental data with excellent statistics. However, meeting such a precision reveals itself to be a challenge for theorists. Indeed, Irfu physicists recently showed that part of the information is lost when deconvoluting GPDs from exclusive processes data. Consequently, conventional extraction techniques will fail to take advantage of forthcoming accurate measurements, promoting theoretical uncertainties as the dominant ones in the quantitative understanding of the 3D nucleon properties. In parallel large-scale simulation datasets promise a connection to generalised parton distributions without information loss but on a small number of kinematic configurations. Augmenting these values by imputing the missing data to obtain a continuous model fulfilling all theoretical constraints remains necessary. Through the CompToN project, physicists from Irfu and CPT will join their complementary expertise to obtain an extraction of quarks and gluons 3D tomography in an innovative way: combining computed datasets with experimental ones using state-of-the-art modelling techniques. Combining both will strongly reduce the theoretical uncertainties associated with experimental extractions. Theoretical, phenomenological and simulation efforts are necessary to take the best of the two worlds and solve at once both the deconvolution problem of experimental data, and the imputation problem of large-scale simulations. At the end of the project, we aim at obtaining a precise tomography of the proton, 10 years in advance with respect to the expectations of the community based on the forthcoming US electron-ion collider.