Nuclear Physics B 992, 116244 (2023)

ISSN: 0550-3213, SCIE

One-loop contributions to decays e b → e a γ and (g − 2)e a anomalies, and Ward identity

L.T. Hue, H.N. Long, V.H. Binh, H.L.T. Mai, T. Phong Nguyen

In this paper, we will present analytic formulas to express one-loop contributions to lepton flavor violating decays eb → ea γ , which are also relevant to the anomalous dipole magnetic moments of charged leptons ea . These formulas were computed in the unitary gauge, using the well-known Passarino-Veltman notations. We also show that our results are consistent with those calculated previously in the ’t Hooft-Veltman gauge, or in the limit of zero lepton masses. At the one-loop level, we show that the appearance of fermion-scalar- vector type diagrams in the unitary gauge will violate the Ward Identity relating to an external photon. As a result, the validation of the Ward Identity guarantees that the photon always couples with two identical particles in an arbitrary triple coupling vertex containing a photon.

DOI: https://doi.org/10.1016/j.nuclphysb.2023.116244

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