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. D313180View full textAdd to dashboardCite

“…The issue of the muon and electron anomalous magnetic moment have been addressed with an additional Z gauge boson [10][11][12][13][14][15][16][17][18]. However, the Z contribution as the singular source of the lepton (g − 2) is always of the same sign unless the nature of the gauge bosonlepton couplings switch over generations [19].…”

Heavy singly charged Higgs bosons and inverse seesaw neutrinos as origins of large $(g-2)_{e,μ}$ in two higgs doublet models

“…µ,e anomalies. Such theories rely on the inclusion of vector-like lepton multiplets [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50],…”

Explaining (g−2)μ,e , the KOTO anomaly, and the MiniBooNE excess in an extended Higgs model with sterile neutrinos

“…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].…”