Anomalies in $^8$Be nuclear transitions and $(g-2)_{e,μ}$: towards a minimal combined explanation

Abstract

Motivated by a simultaneous explanation of the apparent discrepancies in the light charged lepton anomalous magnetic dipole moments, and the anomalous internal pair creation in 8 Be nuclear transitions, we explore a simple New Physics model, based on an extension of the Standard Model gauge group by a U (1) B−L . The model further includes heavy vector-like fermion fields, as well as an extra scalar responsible for the low-scale breaking of U (1) B−L , which gives rise to a light Z boson. The new fields and currents allow to explain the anomalous internal pair creation in 8 Be while being consistent with various experimental constraints. Interestingly, we find that the contributions of the Z and the new U (1) B−L -breaking scalar can also successfully account for both (g − 2) e,µ anomalies; the strong phenomenological constraints on the model's parameter space ultimately render the combined explanation of (g − 2) e and the anomalous internal pair creation in 8 Be particularly predictive. The underlying idea of this minimal "prototype model" can be readily incorporated into other protophobic U (1) extensions of the Standard Model.

Supersymmetric gauged U(1)Lμ−LτBanerjee1, Byakti2, Roy3 2018Phys. Rev. D303180View full textAdd to dashboardCite

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“…A new physics solution is needed to explain them simultaneously. A few possible solutions in other contexts have been considered in literature [14,[91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106].…”