Can electron and muon $g-2$ anomalies be jointly explained in SUSY?

TL;DR

This paper investigates whether the minimal supersymmetric standard model (MSSM) can simultaneously explain the muon and electron g-2 anomalies, identifying viable parameter space consistent with experimental constraints and dark matter considerations.

Contribution

It demonstrates that MSSM can jointly account for both g-2 anomalies at 2σ level by exploring non-universal slepton masses and dark matter scenarios, which was previously challenging.

Findings

Identifies parameter space with specific slepton masses and signs of μM1, μM2 that explain anomalies.

Shows this parameter space survives collider constraints but overproduces dark matter unless alternative candidates are considered.

Suggests superWIMP dark matter can resolve the dark matter overabundance issue.

Abstract

The FNAL+BNL measurements for muon $g-2$ is $4.2\sigma$ above the SM prediction, and the Berkeley $^{133}$Cs measurement for the fine-structure constant $\alpha_{\rm em}$ leads to the SM prediction for electron $g-2$ which is $2.4\sigma$ above the experimental value. Hence, a joint explanation of both anomalies requires a positive contribution to muon $g-2$ and a negative contribution to electron $g-2$, which is rather challenging. In this work we explore the possibility of such a joint explanation in the minimal supersymmetric standard model (MSSM). Assuming no universality between smuon and selectron soft masses, we find out a part of parameter space for a joint explanation at $2\sigma$ level, i.e., $\mu M_1,\mu M_2<0$, $m_{L1}, m_{E2}<200$ GeV, $m_{L2}$ being much larger than the soft masses of other sleptons, $|M_1|<125$ GeV and $\mu<400$ GeV. This part of parameter space can survive LHC and LEP constraints, but gives an over-abundance for dark matter if the bino-like lightest neutralino is assumed to be the dark matter candidate. With the assumption that the dark matter candidate is a superWIMP (say a pseudo-goldstino in multi-sector SUSY breaking scenarios, whose mass can be as light as GeV and produced from the late-decay of the thermally freeze-out lightest neutralino), the dark matter problem can be avoided. So, we conclude that the MSSM may give a joint explanation for the muon and electron $g-2$ anomalies at $2\sigma$ level (the muon $g-2$ anomaly can be even ameliorated to $1\sigma$).