Supersymmetric interpretation of the Egret GeV anomaly, Xenon-10 dark matter search limits, and the CERN LHC

Abstract

The observation of the Egret experiment of an excess of diffuse gamma rays with energies above ${E}_{\ensuremath{\gamma}}=1\text{ }\text{ }\mathrm{GeV}$ has previously been interpreted in the context of the minimal supergravity model (mSUGRA) as coming from neutralino annihilation into mainly $b$-quarks in the galactic halo, with neutralino mass in the vicinity of 50--70 GeV. We observe that, in order to obtain the correct relic abundance of neutralinos in accord with WMAP measurements, the corresponding neutralino-proton direct detection (DD) rates should be in excess of recent limits from the Xenon-10 collaboration. While it does not appear possible to satisfy the Egret, WMAP, and Xenon-10 constraints simultaneously within the mSUGRA model, we find that it is easily possible in models with nonuniversal Higgs soft masses (NUHM). In either case, gluino pair production from ${m}_{\stackrel{\texttildelow{}}{g}}\ensuremath{\sim}400--500\text{ }\text{ }\mathrm{GeV}$ should occur at large rates at the CERN LHC, and a gluino pair production signal should be visible with just $0.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity. The NUHM interpretation predicts a rather light spectrum of heavy Higgs bosons with ${m}_{A}\ensuremath{\sim}140--200\text{ }\text{ }\mathrm{GeV}$ over the whole parameter space which would interpret Egret data. Spin-independent DD rates are predicted to be just above ${10}^{\ensuremath{-}8}\text{ }\text{ }\mathrm{pb}$, within range of the next round of direct dark matter detection experiments.