2025/12/02 by Son, Sangyeong
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Nuclear Theory (nucl-th) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2512.02407
openalex publication_date 2025/12/02 · openalex created_date 2025/12/04 · openalex updated_date 2026/07/28
We present the formalism of hadron-to-two-hadron transition generalized parton distributions (GPDs) for spinless hadron case. Definitions of the twist-2 unpolarized and polarized π→ππ transition GPDs are introduced with a particular choice of kinematic variables that characterize the produced two-pion system. In the vicinity of ρ(770), we work out the two-pion decay angular distributions of the e-π→ e-γππ cross section, incorporating both the Bethe-Heitler and deeply virtual Compton scattering processes. Each cross section exhibits a distinctive angular distribution, which is sensitive to the polarization states of the produced ρ(770) resonance. In addition, we construct the double partial-wave expansion of π→ππ transition GPDs in the two-pion decay angles as a generalization of GPDs for transition from a pion to a spin-ℓ resonance state. With the help of the Omnès representation, we constrain the π→ππ transition GPDs in terms of the low energy ππ scattering phase shift and build a phenomenological model for these GPDs.