Search for anomalous production of prompt like-sign muon pairs and constraints on physics beyond the standard model with the ATLAS detector
Physical Review D - Particles, Fields, Gravitation and Cosmology 85:3 (2012)
Abstract:
An inclusive search for anomalous production of two prompt, isolated muons with the same electric charge is presented. The search is performed in a data sample corresponding to 1.6fb-1 of integrated luminosity collected in 2011 at √s=7TeV with the ATLAS detector at the LHC. Muon pairs are selected by requiring two isolated muons of the same electric charge with p T>20GeV and |η|<2.5. Minimal requirements are placed on the rest of the event activity. The distribution of the invariant mass of the muon pair m(μμ) is found to agree well with the background expectation. Upper limits on the cross section for anomalous production of two muons with the same electric charge are placed as a function of m(μμ) within a fiducial region defined by the event selection. The fiducial cross-section limit constrains the like-sign top-quark pair-production cross section to be below 3.7pb at 95% confidence level. The data are also analyzed to search for a narrow like-sign dimuon resonance as predicted for e.g. doubly charged Higgs bosons (H ±). Assuming pair production of H± bosons and a branching ratio to muons of 100% (33%), this analysis excludes masses below 355 (244)GeV and 251 (209)GeV for H± bosons coupling to left-handed and right-handed fermions, respectively. © 2012 CERN. Published by the American Physical Society under the terms of the uri xlink:href=http://creativecommons.org/licenses/by/3.0/Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. © 2012 American Physical Society.Measurements of the electron and muon inclusive cross-sections in proton-proton collisions at √s=7TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 707:5 (2012) 438-458
Abstract:
This Letter presents measurements of the differential cross-sections for inclusive electron and muon production in proton-proton collisions at a centre-of-mass energy of s=7TeV, using data collected by the ATLAS detector at the LHC. The muon cross-section is measured as a function of pT in the range 4Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 707:5 (2012) 478-496
Abstract:
We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models. © 2011 CERN.Measurement of the ZZ production cross section and limits on anomalous neutral triple gauge couplings in proton-proton collisions at √s=7TeV with the ATLAS detector
Physical Review Letters 108:4 (2012)
Abstract:
A measurement of the ZZ production cross section in proton-proton collisions at √s=7TeV using data corresponding to an integrated luminosity of 1.02fb -1 recorded by the ATLAS experiment at the LHC is presented. Twelve events containing two Z boson candidates decaying to electrons and/or muons are observed, with an expected background of 0.3±0.3(stat)- 0.3+0.4(syst) events. The cross section measured in a phase-space region with good detector acceptance and for dilepton masses within the range 66 to 116 GeV is σZZ→" +" -" +" -fid=19.4-5.2+6.3(stat)-0.7+0. 9(syst)±0.7(lumi)fb. The resulting total cross section for on-shell ZZ production, σZZtot=8.5-2.3+2.7(stat)-0.3+0.4(syst)±0.3(lumi)pb, is consistent with the standard model expectation of 6.5-0.2+0.3pb calculated at the next-to-leading order in QCD. Limits on anomalous neutral triple gauge boson couplings are derived. © 2012 CERN. Published by the American Physical Society under the terms of the < uri xlink:href="http://creativecommons. org/licenses/by/3.0/" > Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Measurement of the cross-section for b-jets produced in association with a Z boson at s=7 TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 706:4-5 (2012) 295-313