Jose Rodriguez-Quintero

Generalised Parton Distributions (GPDs) provide multidimensional insight into hadron structure and are particularly relevant for the pion, whose dynamics are intimately linked to chiral symmetry breaking. We introduce a novel modelling strategy for pion GPDs that satisfies all QCD constraints by construction: support, polynomiality, positivity, and the soft-pion theorem. The approach is illustrated with a simple algebraic model, which is evolved and used to compute deeply virtual Compton scattering (DVCS) Compton Form Factors at next-to-leading order. Our results indicate that gluons dominate the pion response at the Electron Ion Collider kinematics. Published by the Jagiellonian University 2026 authors

Nucleon elastic electromagnetic form factors obtained using both the three-body and quark + fully interacting-diquark pictures of nucleon structure are employed to calculate an array of light-front transverse densities for the proton and neutron and their dressed valence-quark constituents, . flavor separations of the proton and neutron results. These two complementary descriptions of nucleon structure deliver mutually compatible predictions, which match expectations based on modern parametrizations of available data, where such are available. Among other things, it is found that transverse-plane valence u - and d -quark Dirac radii are practically indistinguishable; but regarding kindred Pauli radii, the d quark value is roughly 10% greater than that of the u -quark. Moreover, magnetically, the valence d quark is far more active than the valence u quark, probably because it has much greater orbital angular momentum. Both pictures of nucleon structure agree in predicting that, in a polarized nucleon, the transverse-plane charge densities are no longer rotationally invariant. Instead, for a + x ^ polarized nucleon, positive charge is displaced in the + y ^ direction, with the opposite effect for negative charge.

We investigate the internal structure of a comprehensive set of pseudoscalar and vector mesons, including both flavor-symmetric and flavor-asymmetric systems, by reconstructing their charge distributions from electromagnetic form factors. To achieve this, we employ a Maximum Entropy Method optimized for charge distributions, utilizing previously published form factor data obtained within the Dyson-Schwingers and Bethe-Salpeter equations framework. Furthermore, we calculate the average distance between the valence quark and antiquark that constitute the meson, interpreting it as an estimate for both the meson's spatial size and the typical range of quark motion. Our results reveal that this distance for the lightest quarkonia is approximately five times larger than that for the heaviest. Moreover, due to spin effects, vector mesons exhibit sizes that are 5-15\% larger than their pseudoscalar counterparts.

A symmetry-preserving analysis of strong interaction quantum field equations is used to complete a unified treatment of pion, kaon, and nucleon electromagnetic and gravitational form factors. Findings include a demonstration that the pion near-core pressure is roughly twice that in the proton, so both are significantly greater than that of a neutron star; parton species separations of the nucleon’s three gravitational form factors, in which, inter alia, the glue-to-quark ratio for each form factor is seen to take the same constant value, independent of momentum transfer; and a determination of proton radii orderings, with the mechanical (normal force) radius being less than the mass-energy radius, which is less than the proton charge radius. This body of predictions should prove useful in an era of experiments that will enable them to be tested.

A unified set of predictions for pion, kaon and nucleon gravitational form factors is obtained using a symmetry-preserving truncation of each relevant quantum field equation. A crucial aspect of the study is the self-consistent characterization of the dressed quark-graviton vertices, applied when probing each quark flavor inside mesons or nucleons. The calculations reveal that each hadron's mass radius is smaller than its charge radius, matching available empirical inferences; moreover, core pressures are significantly greater than those in neutron stars. This set of predictions is expected to be instrumental as forthcoming experiments provide opportunities for validation.