Leading-twist to higher-twist generalized parton distributions of the pseudoscalar mesons at non-zero skewness

Abstract

We investigate the multidimensional partonic structure of spin-0 mesons, specifically the pion and the kaon, by evaluating their complete set of eight generalized parton distributions (GPDs) up to twist-4. Utilizing the light-front quark model (LFQM) with the Brodsky-Huang-Lepage (BHL) prescription, we compute these distributions in the kinematically rich non-zero skewness ($\xi \ne 0$) domain, strictly within the DGLAP region, $x\in [\xi ,1]$. To construct a three-dimensional tomographic picture, we perform Fourier transforms of the momentum-space GPDs to obtain the impact parameter dependent parton distribution functions (IPDPDFs) in the transverse plane and the corresponding diffraction patterns in the longitudinal coordinate space. The numerical results explicitly reveal the consequences of $\mathrm{SU}(3)$ flavor symmetry breaking, as the strange quark in the kaon dynamically shifts spatial localizations compared to the lighter up quarks. We also observe that while higher-twist correlations exhibit massive amplitude scaling in the pion, they are heavily suppressed by the larger macroscopic mass of the kaon.

Comments: 31 pages and 7 figures