Abstract
The results of a search for the production of second generation scalar leptoquarks are presented for final states consisting of either two oppositely charged muons and at least two jets or a muon plus missing transverse momentum and at least two jets. A total of 1.03/fb integrated luminosity of proton-proton collision data produced by the Large Hadron Collider at sqrt(s) = 7 TeV and recorded by the ATLAS detector is used for the search. The event yields in the signal regions are found to be consistent with the Standard Model background expectations. The production of second generation leptoquarks is excluded for a leptoquark mass m_LQ < 594 (685) GeV at 95% confidence level, for a branching ratio of 0.5 (1.0) for leptoquark decay to a muon and a quark.
Highlights
The results presented in this paper are an update of the previous ATLAS search for second generation LQs [12] and extend the bounds arising from previous direct searches performed by CMS [13], ATLAS [12], D0 [14] and OPAL [15]
Two control regions are used in the μμjj channel. (I) Z + jets: formed by events within a narrow dimuon invariant mass mμμ window around the Z boson mass, defined by 81 < mμμ < 101 GeV, and at least two jets, and (II) tt: one of the muons is replaced by an electron resulting in events with a muon and an electron, and at least two jets
There is no significant excess in data observed at large LLR values where such a signal would appear, and the data are found to be consistent with the Standard Model (SM) background expectations
Summary
The results presented in this paper are an update of the previous ATLAS search for second generation LQs [12] and extend the bounds arising from previous direct searches performed by CMS [13], ATLAS [12], D0 [14] and OPAL [15]. The final states arising from leptoquark pairs decaying into two muons and two quarks (μμjj ), or into a muon, a neutrino and two quarks (μνjj ), are considered. These result in experimental signatures of either two high transverse momentum (pT) muons and two high pT jets, or one high pT muon, missing transverse momentum, and two high pT jets. Analyses for both dimuon and single muon final states start with the selection of event samples with large signal acceptance. The results are combined and interpreted as lower bounds on the LQ mass for different β hypotheses
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