https://doi.org/10.1140/epjc/s10052-022-10587-4
Regular Article - Theoretical Physics
Backward timelike Compton scattering to decipher the photon content of the nucleon
1
CPHT, CNRS, École Polytechnique, I.P. Paris, 91128, Palaiseau, France
2
National Research Centre Kurchatov Institute: Petersburg Nuclear Physics Institute, 188300, Gatchina, Russia
3
Higher School of Economics, National Research University, 194100, St. Petersburg, Russia
4
National Centre for Nuclear Research, NCBJ, 02-093, Warsaw, Poland
b
kirill.semenov@thd.pnpi.spb.ru
Received:
18
May
2022
Accepted:
4
July
2022
Published online:
30
July
2022
The exclusive photoproduction off nucleon of a large invariant mass lepton pair in the backward region specified by the small Mandelstam variable is discussed in the framework of collinear QCD factorization. The amplitude is factorized in terms of photon-to-nucleon Transition Distribution Amplitudes (TDAs). These new non-perturbative objects, complementary to the “photon-inside-the-nucleon PDF”, lead to a tomographic picture of the nucleon’s photon content after Fourier transforming to the impact parameter space. This allows to address the question of where in the transverse plane the nucleon emits a photon. A simplistic model-estimate of photon-to-nucleon TDAs is used to estimate the magnitude of the corresponding cross sections. The background due to the electromagnetic Bethe–Heitler process is shown to be negligible in the kinematical regime of interest.
© The Author(s) 2022
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3. SCOAP3 supports the goals of the International Year of Basic Sciences for Sustainable Development.