Gravitational form factors of the nucleon from the chiral effective model

Fujii, Daisuke; Kawaguchi, Mamiya*; Tanaka, Mitsuru*

Elucidating the mechanisms by which quarks and gluons are confined within hadrons is the most fundamental challenge in QCD. To solve this problem, it is important to understand the role of quark and gluon condensation and the associated spontaneous symmetry breaking in making hadrons. Recently, the stress distribution inside the proton has become experimentally measurable. It is extracted from the gravitational form factors that characterize the matrix elements of the energy-momentum tensor for the proton. This stress distribution is the force that confines quarks and gluons inside hadrons, opening the way to approach the above issues from the viewpoint of stress distribution. In this talk, we investigate the contributions of phenomena reflecting chiral and scale symmetry breaking, such as quark and gluon condensation, to the pressure distribution inside the nucleon, and show that these contributions are essential for stabilizing the nucleon.