Upper bounds on sparticle masses from muon g − 2 and the Higgs mass and the complementarity of future colliders

Marcin Badziak,Stefan Pokorski,Marek Lewicki,Zygmunt Lalak,Marek Olechowski

doi:10.1007/jhep03(2015)003

Abstract

Supersymmetric (SUSY) explanation of the discrepancy between the measurement of $(g-2)_\mu$ and its SM prediction puts strong upper bounds on the chargino and smuon masses. At the same time, lower experimental limits on the chargino and smuon masses, combined with the Higgs mass measurement, lead to an upper bound on the stop masses. The current LHC limits on the chargino and smuon masses (for not too compressed spectrum) set the upper bound on the stop masses of about 10 TeV. The discovery potential of the future lepton and hadron colliders should lead to the discovery of SUSY if it is responsible for the explanation of the $(g-2)_\mu$ anomaly. This conclusion follows from the fact that the upper bound on the stop masses decreases with the increase of the lower experimental limit on the chargino and smuon masses.

Highlights

We point out that the value of (g − 2)μ gives constraints on the slepton sector but indirectly on the squark sector
We find that the present LEP limits on the smuon and chargino masses together with the requirement of e.g. 1σ agreement with (g −2)μ imply tan β 2.2 This gives rather weak upper bound on the stop masses of about 103-104 TeV
Even a slight improvement in the experimental limits on the smuon and chargino masses would lead to a substantial improvement of the lower bound on tan β and, in turn, to a strong upper bound on the stop masses of order O(10 TeV)

Summary

Upper bounds on the stop masses

It is clear from the previous section that the lower limit on the smuon and chargino masses translates into a lower bound on tan β, if the (g − 2)μ anomaly is to be explained by supersymmetric contributions. In the right panel of figure 4 we plot the upper bound on the stop masses as a function of a common hypothetical experimental lower limits on the smuon and chargino masses for several values of aSμUSY. If the lower experimental limit on the chargino and smuon masses was set at around 300 GeV even the 2σ agreement with the current (g − 2)μ measurement would imply the upper bound on the stop masses around 10 TeV. These upper bounds can disappear if the singlet-like scalar is heavier than the SM-like Higgs (but not decoupled) because their mixing gives negative contribution to the Higgs mass and may cancel a too large logarithmic correction from very heavy stops Another point worth emphasizing is that SUSY spectrum consistent with the (g − 2)μ measurement does not have to be much split, especially for large values of tan β. All slepton and chargino masses can be above 500 GeV, while stops can be around 1 TeV if a large stop mixing is present [62] and/or a mixing with additional light singlet-like scalar is introduced [63], as in the NMSSM

Conclusions

Findings

A Bino contribution