Off-shell generalized parton distributions and form factors of the pion

Off-shell effects in generalized parton distributions (GPDs) of the pion, appearing, e.g., in the Sullivan process, are considered. Due to the lack of crossing symmetry, the moments of GPDs involve also odd powers of the skewness (longitudinal momentum transfer) parameter, which results in emergence of new off-shell form factors. With current-algebra techniques, we derive exact relations between the four off-shell gravitational form factors of the pion, in analogy to the electromagnetic case. Our results place stringent constraints on the off-shell GPDs of the pion. We provide an explicit realization in terms of a chiral quark model, where we show that the off-shell effects in GPDs are potentially significant in modeling physical processes and should not be neglected. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.

Automated summary

This paper considers the off-shell effects in the generalized parton distributions (GPDs) of the pion, particularly in the Sullivan process. The lack of crossing symmetry in GPDs leads to the involvement of odd powers of the skewness parameter, resulting in the emergence of new off-shell form factors. Using current-algebra techniques, the authors derive exact relations between the four off-shell gravitational form factors of the pion, similar to the electromagnetic case. The findings of this study place strict constraints on the off-shell GPDs of the pion and emphasize the significance of considering off-shell effects in modelling physical processes.