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

TL;DR

The paper analyzes the consequences of a potential $m_h\approx 125$ GeV Higgs for SUSY parameter spaces, computing $m_h$ with full radiative corrections and scanning both mSUGRA and NUHM2. It finds that in mSUGRA, achieving $m_h\simeq 125$ GeV favors $m_0\gtrsim 0.8$ TeV and $A_0\sim \pm 2m_0$, yielding a heavy scalar spectrum and limiting neutralino annihilation channels, while in NUHM2 the constraints are looser, allowing lighter sleptons/charginos and mixed bino–higgsino DM that can align with WMAP under certain conditions. The study also shows that $(g-2)_\mu$ is not explained by these scenarios at $m_h\approx 125$ GeV, flavor observables remain compatible with SM-like values, and DM relic density is typically overproduced in standard cosmology unless a higgsino-like LSP or non-standard cosmologies are invoked. Direct and indirect detection prospects depend strongly on the DM realization, with well-tempered neutralinos offering the best near-future sensitivity. These results imply that LHC SUSY searches may predominantly probe gluino-rich, heavy-scalar spectra, and that dark matter signals hinge on cosmological assumptions and neutralino composition.

Abstract

The ATLAS and CMS collaborations have reported an excess of events in the γγ, ZZ^*\to 4\ell and WW^* search channels at an invariant mass m \simeq 125 GeV, which could be the first evidence for the long-awaited Higgs boson. We investigate the consequences of requiring m_h\simeq 125 GeV in both the mSUGRA and NUHM2 SUSY models. In mSUGRA, large values of trilinear soft breaking parameter |A_0| are required, and universal scalar m_0\agt 0.8 TeV is favored so that we expect squark and slepton masses typically in the multi-TeV range. This typically gives rise to an "effective SUSY" type of sparticle mass spectrum. In this case, we expect gluino pair production as the dominant sparticle creation reaction at LHC. For m_0< 5 TeV, the superpotential parameter μ> 2 TeV and m_A> 0.8 TeV, greatly restricting neutralino annihilation mechanisms. These latter conclusions are softened if m_0\sim 10-20 TeV or if one proceeds to the NUHM2 model. The standard neutralino abundance tends to be far above WMAP-measured values unless the neutralino is higgsino-like. We remark upon possible non-standard (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.