2025/11/17 by Li, Cong
Physics and Astronomy · #Particle physics theoretical and experimental studies #Particle Detector Development and Performance #High-Energy Particle Collisions Research
paper · doi:10.48550/arxiv.2511.14800
We study how background electromagnetic fields modify quasi-real photon emission at the EIC and EicC through an effective coupling correction, thereby altering the photon flux spectrum. The resulting change in lepton-pair production via photon-photon fusion, where one photon arises from the electron and the other from the nuclear Coulomb field-serves as a clean QED probe of such background effects. In our formulation, the correction originates from a non-perturbative modification of the photon propagator induced by the background field. Because this process shares the same initial-state photon dynamics as photon-gluon fusion, any background-induced alteration of the photon propagator directly impacts the extraction of small-x gluon distributions. Numerical estimates at realistic collider energies indicate that these corrections should be non-negligible in certain kinematic regions.