Light Cone Sum Rules and Form Factors for $p\rightarrow e^+ \gamma$

Abstract

Proton decay is a baryon number violating process, and hence is forbidden in the Standard Model (SM) of particle physics. Baryon number violation is expected to be an important criteria to explain the matter-anti-matter asymmetry of the universe. Any detection of the proton decay will be a direct evidence of physics beyond the SM. In SMEFT, proton decay is possible via baryon number violating dimension-6 operators. In this work, we pay attention to the decay channel $p\rightarrow e^+ \gamma$ which is expected to be an experimentally cleaner channel due to less nuclear absorption. The gauge invariant amplitude of this process involves two form factors. We calculate these form factors in the framework of light cone sum rules (LCSR) using photon DAs upto two particle twist-3 accuracy as well as proton DAs of twist-3 accuracy. We find that the form factors calculated using photon DAs are more reliable.