Search for charginos nearly mass degenerate with the lightest neutralino based on a disappearing-track signature in pp collisions at √(s) = 8 TeV with the ATLAS detector
Physical Review D - Particles, Fields, Gravitation and Cosmology 88:11 (2013) 112006-1-112006-23
Abstract:
A search is presented for direct chargino production based on a disappearing-track signature using 20:3 fb-1 of proton-proton collisions at √s = 8 TeV collected with the ATLAS experiment at the LHC. In anomaly-mediated supersymmetry breaking (AMSB) models, the lightest chargino is nearly mass degenerate with the lightest neutralino and its lifetime is long enough to be detected in the tracking detectors by identifying decays that result in tracks with no associated hits in the outer region of the tracking system. Some models with supersymmetry also predict charginos with a significant lifetime. This analysis attains sensitivity for charginos with a lifetime between 0.1 and 10 ns, and significantly surpasses the reach of the LEP experiments. No significant excess above the background expectation is observed for candidate tracks with large transverse momentum, and constraints on chargino properties are obtained. In the AMSB scenarios, a chargino mass below 270 GeV is excluded at 95% confidence level.Search for long-lived stopped R-hadrons decaying out of time with pp collisions using the ATLAS detector
Physical Review D - Particles, Fields, Gravitation and Cosmology 88:11 (2013) 112003-1-112003-30
Abstract:
An updated search is performed for gluino, top squark, or bottom squark R-hadrons that have come to rest within the ATLAS calorimeter, and decay at some later time to hadronic jets and a neutralino, using 5.0 and 22:9 fb-1 of pp collisions at 7 and 8 TeV, respectively. Candidate decay events are triggered in selected empty bunch crossings of the LHC in order to remove pp collision backgrounds. Selections based on jet shape and muon system activity are applied to discriminate signal events from cosmic ray and beam-halo muon backgrounds. In the absence of an excess of events, improved limits are set on gluino, stop, and sbottom masses for different decays, lifetimes, and neutralino masses. With a neutralino of mass 100 GeV, the analysis excludes gluinos with mass below 832 GeV (with an expected lower limit of 731 GeV), for a gluino lifetime between 10 μs and 1000 s in the generic R-hadron model with equal branching ratios for decays to (formula presented) and (formula presented). Under the same assumptions for the neutralino mass and squark lifetime, top squarks and bottom squarks in the Regge R-hadron model are excluded with masses below 379 and 344 GeV, respectively.W-boson polarization measurement in the t(t)over-bar dilepton channel using the CDF II detector
PHYSICS LETTERS B 722:1-3 (2013) 48-54
Production of KS0, K*± (892) and φ0 (1020) in minimum bias events and K0S and Λ0 in jets in p (p)over-barcollisions at √S 1: 96 TeV
PHYSICAL REVIEW D 88:9 (2013) ARTN 092005
Search for a dijet resonance in events with jets and missing transverse energy in p(p)over-bar collisions at √S 1: 96 TeV
PHYSICAL REVIEW D 88:9 (2013) ARTN 92004