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Register a new userDiscovering Gluino Events at LHC-8 via Disappearing Chargino Tracks
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In this note, we advocate a new method for identifying gluino pair production events at the LHC. The method is motivated by and works for theories with heavy squarks and Wino-like LSPs (with nearly degenerate LSP and chargino). Such theories are well motivated and their gluinos typically have a O(50%) branching ratio to charged Winos. Observing the track of a long lived charged Wino produced from gluino decay could give a clear identification of a gluino event. Charged Wino NLSPs produced in colliders can be long-lived enough to leave a reconstructable high pT charged track before decaying into a soft pion (or a soft lepton) and the LSP, a signature with low SM background. By supplementing the canonical gluino search strategy with a search for these stiff chargino tracks, our results suggest it will be possible to find gluinos with significantly less luminosity. In addition, we describe a procedure for obtaining a kinematic measurement of the gluino mass using the three momenta of the reconstructed chargino tracks. With measurements of the gluino mass and cross section, it will be possible to determine the gluino spin, and confirm that the excess events are indeed due to a spin 1/2 superpartner. It may also be possible to use these stiff Wino tracks to obtain an approximate measurement of the chargino mass, and therefore the LSP (dark matter) mass.
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In this note we discuss a characteristic collider signature of models of gauge mediated supersymmetry breaking in which the selectron and smuon are mass-degenerate co-NLSP. In these models, all processes involving superpartners give rise to two NLSP selectrons or smuons, each of which subsequently decays to a nearly massless LSP gravitino and an electron or a muon. In a large region of the parameter space, the NLSPs travel macroscopic distances, of the order 0.1-1000 mm, before they decay. Hence, these models give rise to collider signatures involving charged tracks that end at vertices, which are inside the detector volume but displaced with respect to the original collision point, from which an electron or a muon is emitted. In order to probe this class of models we propose a search for disappearing charged tracks in association with displaced electrons or muons.
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