ATLAS

Abstract:

The result of a search for heavy long-lived charged particles produced in pp collisions at √s=7 TeV at the LHC is described. The data sample has been collected using the CMS detector and corresponds to an integrated luminosity of 5.0 fb -1. The inner tracking detectors are used to define a sample of events containing tracks with high momentum and high ionization energy loss. A second sample of events, which have high-momentum tracks satisfying muon identification requirements in addition to meeting high-ionization and long time-of-flight requirements, is analyzed independently. In both cases, the results are consistent with the expected background estimated from data. The results are used to establish cross section limits as a function of mass within the context of models with long-lived gluinos, scalar top quarks and scalar taus. Cross section limits on hyper-meson particles, containing new elementary long-lived hyper-quarks predicted by a vector-like confinement model, are also presented. Lower limits at 95% confidence level on the mass of gluinos (scalar top quarks) are found to be 1098 (737) GeV/c 2. A limit of 928 (626) GeV/c 2 is set for a gluino (scalar top quark) that hadronizes into a neutral bound state before reaching the muon detectors. The lower mass limit for a pair produced scalar tau is found to be 223 GeV/c 2. Mass limits for a hyper-kaon are placed at 484, 602, and 747 GeV/c 2 for hyper-ρ masses of 800, 1200, and 1600 GeV/c 2, respectively. © 2012 CERN.

Abstract:

A blind analysis searching for the decay Bs 0→μ+μ- has been performed using proton-proton collisions at a centre-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. With an integrated luminosity of 2.4 fb-1 no excess of events over the background expectation is found and an upper limit is set on the branching fraction BR(Bs 0→μ+μ-)<2.2(1.9)×10-8 at 95% (90%) confidence level. © 2012 CERN.

Abstract:

A blind analysis searching for the decay Bs ⁰→μ⁺μ^- has been performed using proton-proton collisions at a centre-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. With an integrated luminosity of 2.4 fb^-1 no excess of events over the background expectation is found and an upper limit is set on the branching fraction BR(Bs ⁰→μ⁺μ^-)<2.2(1.9)×10-8 at 95% (90%) confidence level. © 2012 CERN.

Abstract:

We report a set of measurements of inclusive invariant p T differential cross sections of Λ0, Λ ̄0, Ξ ±, and Ω ± hyperons reconstructed in the central region with pseudorapidity |η|<1 and p T up to 10GeV/c. Events are collected with a minimum-bias trigger in pp̄ collisions at a center-of-mass energy of 1.96 TeV using the CDF II detector at the Tevatron Collider. As p T increases, the slopes of the differential cross sections of the three particles are similar, which could indicate a universality of the particle production in p T. The invariant differential cross sections are also presented for different charged-particle multiplicity intervals. © 2012 American Physical Society.