Implications of a 125 GeV Higgs scalar for the LHC supersymmetry and neutralino dark matter searches

Abstract

The ATLAS and CMS collaborations have reported an excess of events in the $\ensuremath{\gamma}\ensuremath{\gamma}$, $Z{Z}^{*}\ensuremath{\rightarrow}4\ensuremath{\ell}$ and $W{W}^{*}$ search channels at an invariant mass $m\ensuremath{\simeq}125\text{ }\text{ }\mathrm{GeV}$, which could be the first evidence for the long-awaited Higgs boson. We investigate the consequences of requiring ${m}_{h}\ensuremath{\simeq}125\text{ }\text{ }\mathrm{GeV}$ in both the minimal supergravity and 2-parameter nonuniversal Higgs supersymmetric models. In minimal supergravity, large values of trilinear soft breaking parameter $|{A}_{0}|$ are required, and universal scalar ${m}_{0}\ensuremath{\gtrsim}0.8\text{ }\text{ }\mathrm{TeV}$ is favored so that we expect squark and slepton masses typically in the multi-TeV range. This typically gives rise to an ``effective supersymmetric'' type of sparticle mass spectrum. In this case, we expect gluino pair production as the dominant sparticle creation reaction at LHC. For ${m}_{0}\ensuremath{\lesssim}5\text{ }\text{ }\mathrm{TeV}$, the superpotential parameter $\ensuremath{\mu}\ensuremath{\gtrsim}2\text{ }\text{ }\mathrm{TeV}$ and ${m}_{A}\ensuremath{\gtrsim}0.8\text{ }\text{ }\mathrm{TeV}$, greatly restricting neutralino annihilation mechanisms. These latter conclusions are softened if ${m}_{0}\ensuremath{\sim}10--20\text{ }\text{ }\mathrm{TeV}$ or if one proceeds to the 2-parameter nonuniversal Higgs model. The standard neutralino abundance tends to be far above WMAP-measured values unless the neutralino is Higgsino-like. We remark upon possible nonstandard (but perhaps more attractive) cosmological scenarios which can bring the predicted dark matter abundance into accord with the measured value, and discuss the implications for direct and indirect detection of neutralino cold dark matter.