Distribution of strong forces on quarks in the proton from DVCS experiments.

The structure of the proton, the nucleus of the hydrogen atom, has been studied in electron scattering for over 60 years, and resulted in a wealth of knowledge of its substructure expressed in electromagnetic form factors and in parton distribution functions (PDFs). Yet, there is a complete lack of knowledge of the protons mechanical or gravitational properties. These are expressed in terms of internal forces, angular momentum and mass distributions. This situation has only recently changed with experiments that study the protons internal structure in deeply virtual Compton scattering  (DVCS), a process that is linked to the gravitational structure through sum rules of GPDs. The extraction of radial and shear forces makes use of the connection of the DVCS process to the unpolarized GPD H(x,x,t) and, through a sum rule to the gravitational form factor d₁(t). This form factor is one of the 3 scalar form factors of the proton’s energy-momentum tensor, and it encodes the distribution of forces and pressure inside the proton.  In this talk we present the first extraction of the shear forces in the proton from the DVCS data taken with CLAS at Jefferson Lab, and discuss prospects of employing new data at higher precision from CLAS12 covering a larger kinematic range.