Many faces of low mass neutralino dark matter in the unconstrained MSSM, LHC data and new signals

A bstract If all strongly interacting sparticles (the squarks and the gluinos) in an un- constrained minimal supersymmetric standard model (MSSM) are heavier than the corre- sponding mass lower limits in the minimal supergravity (mSUGRA) model, obtained by the current LHC experiments, then the existing data allow a variety of electroweak (EW) sectors with light sparticles yielding dark matter (DM) relic density allowed by the WMAP data. Some of the sparticles may lie just above the existing lower bounds from LEP and lead to many novel DM producing mechanisms not common in mSUGRA. This is illustrated by revisiting the above squark-gluino mass limits obtained by the ATLAS Collaboration, with an unconstrained EW sector with masses not correlated with the strong sector. Using their selection criteria and the corresponding cross section limits, we find at the generator level using Pythia, that the changes in the mass limits, if any, are by at most 10-12 % in most scenarios. In some cases, however, the relaxation of the gluino mass limits are larger (≈ 20 %). If a subset of the strongly interacting sparticles in an unconstrained MSSM are within the reach of the LHC, then signals sensitive to the EW sector may be obtained. This is illustrated by simulating the blj T , l = e and μ, and bτ j T signals in i) the light stop scenario and ii) the light stop-gluino scenario with various light EW sectors allowedby the WMAP data. Some of the more general models may be realized with non-universal scalar and gaugino masses.