Improved $${(g-2)_\mu }$$ measurements and wino/higgsino dark matter

Abstract

The electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM) can account for a variety of experimental data. In particular it can explain the persistent $$3-4\,\sigma $$ 3 - 4 σ discrepancy between the experimental result for the anomalous magnetic moment of the muon, $$(g-2)_\mu $$ ( g - 2 ) μ , and its Standard Model (SM) prediction. The lightest supersymmetric particle (LSP), which we take as the lightest neutralino, $${\tilde{\chi }}_{1}^0$$ χ ~ 1 0 , can furthermore account for the observed Dark Matter (DM) content of the universe via coannihilation with the next-to-LSP (NLSP), while being in agreement with negative results from Direct Detection (DD) experiments. Concerning the unsuccessful searches for EW particles at the LHC, owing to relatively small production cross-sections a comparably light EW sector of the MSSM is in full agreement with the experimental data. The DM relic density can fully be explained by a mixed bino/wino LSP. Here we take the relic density as an upper bound, which opens up the possibility of wino and higgsino DM. We first analyze which mass ranges of neutralinos, charginos and scalar leptons are in agreement with all experimental data, including relevant LHC searches. We find roughly an upper limit of $$\sim 600 \,\, \mathrm {GeV}$$ ∼ 600 GeV for the LSP and NLSP masses. In a second step we assume that the new result of the Run 1 of the “MUON G-2” collaboration at Fermilab yields a precision comparable to the existing experimental result with the same central value. We analyze the potential impact of the combination of the Run 1 data with the existing $$(g-2)_\mu $$ ( g - 2 ) μ data on the allowed MSSM parameter space. We find that in this case the upper limits on the LSP and NLSP masses are substantially reduced by roughly $$100 \,\, \mathrm {GeV}$$ 100 GeV . We interpret these upper bounds in view of future HL-LHC EW searches as well as future high-energy $$e^+e^-$$ e + e - colliders, such as the ILC or CLIC.

The tiny (g-2) muon wobble from small-μ supersymmetry

“…Related recent (but prior to the publication of the Fermilab Muon (g-2) result) studies can, for example, be found in refs. [69,70,[85][86][87][88][89][90]. One crucial difference between our study and the very recent work in refs.…”

“…In this way, our MSSM scenario explores a different region of parameter space than the one considered in the study of refs. [69,70], which considers regions of large µ as a way to accommodate current SIDD bounds. We summarize and conclude in section 3.…”

“…One crucial difference between our study and the very recent work in refs. [69,70] is that the spin-independent direct detection (SIDD) cross section is suppressed not by decoupling the Higgsino and heavy Higgs contributions, but by a partial cancellation between the amplitudes mediated by the two neutral CP-even Higgs boson mass eigenstates. This cancellation requires opposite signs of the Higgsino and the Bino mass parameters, (µ × M 1 ) < 0 [68].…”

The new “MUON G-2” result and supersymmetry

“…On the other hand, the analysis for compressed higgsino-like spectra at the HL-LHC, see the discussion in Ref. [8], may exclude…”

“…More recently in Ref [8]. we updated the analysis using the DM relic density only as an upper bound.…”