Inclusive search for same-sign dilepton signatures in pp collisions at $ \sqrt {s} = 7 $ TeV with the ATLAS detector

Abstract

An inclusive search is presented for new physics in events with two isolated leptons (e or µ) having the same electric charge. The data are selected from events collected from pp collisions at √ s = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb −1 . The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, eµ and µµ channels. Four models predicting samesign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks.

Search for Lepton Number Violating DecaysB+→π−μ+μ+andB+Aaij1, Beteta2, Adeva3 et al. 2012Phys. Rev. Lett.Self Cite421180View full textAdd to dashboardCite

“…New physics models such as those with Majorana neutrinos [1] or left-right symmetric models with a doubly charged Higgs boson [2] can violate lepton number conservation and searches for lepton number violating decays are therefore of fundamental importance. Such decays have previously been searched for in both rare decay processes [3][4][5] and in same-sign dilepton searches [6].…”

Searches for Majorana neutrinos inB−decays

“…For all the modes considered in this paper, we search only for decays with muons in the final state, though electrons, and leptons in cases where sufficient energy is available, could also be produced. Searches have also been carried out looking for like-sign dileptons in hadron collider experiments [11].…”

Heavy Majorana neutrino production at future ep colliders

“…These kinds of backgrounds are taken into account in our analysis. For the muon production channel, the charge mis-identification is negligible due to the almost absence of photons converting to muons [47,48]. At 2σ (3σ) [5σ] significance, the required luminosity as a function of m N at LHeC, FCC-ep and ILC⊗FCC are displayed in Fig.…”