Muon g−2, dark matter detection and accelerator physics

We examine the recently observed deviation of the muon g−2 from the Standard Model prediction within the framework of gravity mediated SUGRA models with R-parity invariance. Universal soft breaking (mSUGRA) models, and models with nonuniversal Higgs and third generation squark/slepton masses at MG are considered. All relic density constraints from stau–neutralino co-annihilation and large tanβ NLO corrections for b→sγ decay are included, and we consider two possibilities for the light Higgs: mh>114 GeV and mh>120 GeV. The combined mh, b→sγ and aμ bounds give rise to lower bounds on tanβ and m1/2, while the lower bound on aμ gives rise to an upper bounds on m1/2. These bounds are sensitive to A0, e.g., for mh>114 GeV, the 95% C.L. is tanβ>7(5) for A0=0(−4m1/2), and for mh>120 GeV, tanβ>15(10). The positive sign of the aμ deviation implies μ>0, eliminating the extreme cancellations in the dark matter neutralino–proton detection cross section so that almost all the SUSY parameter space should be accessible to future planned detectors. Most of the allowed parts of parameter space occur in the co-annihilation region where m0 is strongly correlated with m1/2. The lower bound on aμ then greatly reduces the allowed parameter space. Thus using 90% C.L. bounds on aμ we find for A0=0 that tanβ⩾10 and for tanβ⩽40 that m1/2=(290–550) GeV and m0=(70–300) GeV. Then the tri-lepton signal and other SUSY signals would be beyond the Tevatron Run II (except for the light Higgs), only the τ̃1 and h and (and for part of the parameter space) the ẽ1 will be accessible to a 500 GeV NLC, while the LHC would be able to see the full SUSY mass spectrum.