2020/12/17 by Matthias Heller, Niklas Keil, Marc Vanderhaeghen
Physics and Astronomy · #Amplitude #Asymmetry #Compton scattering #Helicity #High-Energy Particle Collisions Research #Nuclear physics #Observable #Particle physics #Particle physics theoretical and experimental studies #Parton #Photon #Photon energy #Physics #Proton #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum electrodynamics #Quantum mechanics #Radiative transfer #Scattering #Scattering amplitude #hep-ph #nucl-th
paper · pdf · doi:10.1103/physrevd.103.036009
published as Phys. Rev. D 103, 036009 (2021) · 16 pages, 13 figures
arxiv created 2020/12/17 · openalex created_date 2020/12/21 · openalex publication_date 2021/02/11 · arxiv updated 2021/02/17 · openalex updated_date 2026/08/06
We evaluate the leading-order QED radiative corrections to the timelike Compton scattering (TCS) process \ensuremathγp\ensuremath→l^\ensuremath-l+p. We study these corrections in two energy regimes using different models for the TCS amplitude. In the low-energy regime we calculate the contribution due to the proton and its lowest-energy excitation, the \mathrm\ensuremathΔ(1232) resonance. In the high-energy near-forward kinematical regime we calculate the TCS amplitude in a handbag approach in terms of generalized parton distributions (GPDs). On the level of cross sections we find the QED radiative corrections to be in the 5%--10% range in the low-energy regime and around 20% in the high-energy regime. We show that in both the dilepton forward-backward asymmetry as well as in the photon beam helicity asymmetry these corrections nearly cancel out, making them gold-plated observables to extract the real and imaginary parts of the TCS amplitude. We demonstrate in particular the sensitivity of these asymmetries on GPD parametrizations for a recent CLAS12@JLab TCS experiment.