Electron and muon (g − 2) in the B-LSSM

Abstract

The theoretical predictions in the standard model (SM) and measurements on the anomalous magnetic dipole moments (MDM) of muon and electron have great precision, hence the MDMs of muon and electron have close relation with the new physics (NP) beyond the SM. Recently, a negative ∼ 2.4σ discrepancy between the measured electron MDM and the SM prediction results from a recent improved determination of the fine structure constant. Combined with the longlasting muon MDM discrepancy which is about ∼ 3.7σ, it is difficult to explain both the magnitude and opposite signs of the deviations in a consistent model, without introducing large flavourviolating effects. The analysis shows that they can be explained in the minimal supersymmetric extension (MSSM) of the SM with local B − L gauge symmetry (B-LSSM). Comparing with the MSSM, new parameters in the B-LSSM can affect the theoretical predictions on lepton MDMs, and the effects of them are explored. PACS numbers:

Anomalies in 8Be nuclear transitions and (g − 2)e,μ: towards a minimal combined explanation

“…The observed pattern for ∆a e and ∆a µ further suggests the underlying presence of New Physics (NP) potentially violating the universality of lepton flavours. Several attempts have been recently conducted to simultaneously explain the tensions in both ∆a e,µ (see for example [100][101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116][117]): in particular, certain scenarios have explored a chiral enhancement, due to heavy vector-like leptons in the one-loop dipole operator, which can potentially lead to sizeable contributions for the leptonic magnetic moments; however, this can open the door to charged lepton flavour violating interactions (new physics fields with non-trivial couplings to both muons and electrons can potentially lead to sizeable rates for µ → eγ, µ → 3e and µ − e conversion), already in conflict with current data [118]. Controlled couplings of electrons and muons to beyond the Standard Model (BSM) fields in the loop (subject to "generation-wise" mixing between SM and heavy vector-like fields) can be achieved, and this further allows to evade the potentially very stringent constraints from charged lepton flavour violating (cLFV) µ − e transitions.…”

An explanation for the muon and electron g − 2 anomalies and dark matter

“…Interestingly, this measurement also shows a possible disagreement between the data and theory, with the measured value lower than the SM prediction by JHEP09(2020)119 about 2.4σ [13]. These tantalizing opposite deviations have invited many studies to explore suitable NP models [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”

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

“…In tandem, there have also been ample attempts to resolve the matter of electron and muon magnetic moments within a supersymmetric framework [20][21][22][23][24][25][26][27][28][29][30][31]. Considering that the lepton (g − 2) from minimal SUSY sources are also always of the same sign, these proposals utilize the effects of large flavor non-universal A-terms [25][26][27][28][29] or flavorviolating SUSY-breaking terms [30,31]. Notwithstanding the fact that such effects could be challenging to incorporate in a consistent SUSY-breaking mechanism, the former suffer from the possibilities of large fine-tuning in the lepton mass matrix and charge-breaking minima of the scalar potential.…”