A new idea of dipole moments in the tau lepton in ultra-peripheral heavy ion collisions

A new idea of dipole moments in the tau lepton in ultra-peripheral heavy ion collisionsPrecise measurements of the anomalous magnetic (MDM) and electric dipole moments (EDM) of leptons are essential for exploring potential new physics beyond the Standard Model.However, a major challenge is posed by the short lifetime of the tau lepton, which makes it impossible to measure its MDM and EDM directly using techniques similar to those used for the electron and muon.Ultraperipheral heavy ion collisions (UPCs) 1-4 offer a viable alternative, taking advantage of the dominant electromagnetic interactions to produce di-lepton pairs.Recently, the observation of tau-pair production in UPCs has been reported by both the ATLAS and CMS collaborations 5,6.These results provide strong constraints on the MDM and EDM with a precision competitive with lepton colliders 7.In a recent study 8, Shao, Yan, Yuan and Zhang have explored the potential of spin asymmetry in tau-pair production within UPCs as a novel observable for assessing the MDM and EDM.Their investigation of azimuthal angular asymmetries provides a significant refinement over traditional cross-sectional analyses, resulting in improved constraints.Using pseudo-data based on measurements from the ATLAS and CMS collaborations, the authors have successfully demonstrated that this new method provides robust constraints on both the MDM and EDM of the tau-pair simultaneously.The new idea proposed by the authors opens up a possible new avenue for studying physics beyond the Standard Model through heavy ion collisions at the LHC.