Impact parameter and transverse charge densities of the pion and kaon

Abstract

The impact parameter and transverse charge densities provide spatially resolved information on hadron structure and probe the interplay between dynamical chiral symmetry breaking and SU(3)-flavor symmetry breaking. We investigate the valence-quark distributions of the pion and kaon using their unpolarized vector GPDs at nonzero skewness $ξ$ within the covariant Nambu--Jona-Lasinio model, with ultraviolet divergences regulated by the Schwinger proper-time scheme. Increasing $ξ$ shifts the distributions toward smaller $x$, reduces their central magnitude at $b_\perp=0$, and broadens their transverse profiles. These results provide insight into the spatial structure of the pion and kaon and offer stringent tests of nonperturbative QCD dynamics, with relevance to forthcoming measurements at Jefferson Lab and the Electron-Ion Collider.