Perturbative and non-perturbative effects in ultraperipheral production of lepton pairs

TL;DR

This paper investigates how both perturbative and non-perturbative effects influence ultraperipheral lepton pair production in ion collisions, highlighting the significant role of the SGS factor in low-mass electron pairs and potential astrophysical implications.

Contribution

It introduces the impact of non-perturbative SGS effects on lepton pair production, especially for low-mass pairs, and discusses observable consequences at collider experiments and in astrophysics.

Findings

Enhanced production of low-mass e+e- pairs due to SGS factor

Finite mass distribution at lowest masses for non-relativistic pairs

Potential increase in 511 keV photon emission from pair annihilation

Abstract

Perturbative and non-perturbative terms of the cross sections of ultraperipheral production of lepton pairs in ion collisions are taken into account. It is shown that production of low-mass $e^+e^-$ pairs is strongly enhanced (compared to perturbative estimates) due to the non-perturbative Sommerfeld-Gamow-Sakharov (SGS) factor. Coulomb attraction of the non-relativistic components of those pairs leads to the finite value of their mass distribution at lowest masses. Their annihilation can result in the increased intensity of 511 keV photons. It can be recorded at the NICA collider and is especially crucial in astrophysical implications regarding the 511 keV line emitted from the Galactic center. The analogous effect can be observed in lepton pairs production at LHC. Energy spectra of lepton pairs created in ultraperipheral nuclear collisions and their transverse momenta are calculated.