[Show abstract][Hide abstract] ABSTRACT: Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top quark (the top squark) and the Higgs boson (Higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 fb-1 of proton-proton collision data at s=8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the top squark mass below 360 to 410 GeV, depending on the Higgsino mass.
[Show abstract][Hide abstract] ABSTRACT: The discovery by the ATLAS and CMS experiments of a new boson with mass
around 125 GeV and with measured properties compatible with those of a
Standard-Model Higgs boson, coupled with the absence of discoveries of
phenomena beyond the Standard Model up to scales of several hundred GeV, has
triggered interest in ideas for future Higgs factories. A new circular e+e-
collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive
solutions proposed so far. It has a clean experimental environment, produces
high luminosity for top-quark, Higgs boson, W and Z studies, accommodates
multiple detectors, and can reach energies up to the t-tbar threshold and
beyond. It will enable measurements of the Higgs boson properties and of
Electroweak Symmetry-Breaking (EWSB) parameters with unequalled precision,
offering exploration of physics beyond the Standard Model in the multi-TeV
range. Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron
machine in the same tunnel, it builds up a long-term vision for particle
physics. Altogether, the combination of TLEP and the VHE-LHC offers, for a
great cost effectiveness, the best precision and the best search reach of all
options presently on the market. This paper presents a first appraisal of the
salient features of the TLEP physics potential, to serve as a baseline for a
more extensive design study.
Journal of High Energy Physics 01/2014; 01:164. · 5.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A search for anomalous production of events with three or more isolated leptons and bottom-quark jets produced in pp collisions at √s=8 TeV is presented. The analysis is based on a data sample corresponding to an integrated luminosity of 19.5 fb(-1) collected by the CMS experiment at the LHC in 2012. No excess above the standard model expectations is observed. The results are interpreted in the context of supersymmetric models with signatures that have low missing transverse energy arising from light top-squark pair production with R-parity-violating decays of the lightest supersymmetric particle. In two models with different R-parity-violating couplings, top squarks are excluded below masses of 1020 GeV and 820 GeV when the lightest supersymmetric particle has a mass of 200 GeV.
[Show abstract][Hide abstract] ABSTRACT: Searches for anomalous top quark-antiquark production are presented, based on pp collisions at √s=8 TeV. The data, corresponding to an integrated luminosity of 19.7 fb−1, were collected with the CMS detector at the LHC. The observed ttbar invariant mass spectrum is found to be compatible with the standard model prediction. Limits on the production cross section times branching fraction probe, for the first time, a region of parameter space for certain models of new physics not yet constrained by precision measurements.