Search for First Generation Scalar Leptoquarks in the Evjj Channel in Pp Collisions at Sqrt(s)

Search for First Generation Scalar Leptoquarks in the Evjj Channel in Pp Collisions at Sqrt(s)
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Total Pages: 29
Release: 2011
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A search for pair-production of first generation scalar leptoquarks is performed in the final state containing an electron, a neutrino, and at least two jets using proton-proton collision data at sqrt(s)=7 TeV. The data were collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 36 inverse picobarns. The number of observed events is in good agreement with the predictions for standard model processes. Prior CMS results in the dielectron channel are combined with this electron+neutrino search. A 95% confidence level combined lower limit is set on the mass of a first generation scalar leptoquark at 340 GeV for beta=0.5, where beta is the branching fraction of the leptoquark to an electron and a quark. These results represent the most stringent direct limits to date for values of beta greater than 0.05.

Search for Pair Production of First and Second Generation Leptoquarks in Proton-proton Collisions at $\sqrt{s}

Search for Pair Production of First and Second Generation Leptoquarks in Proton-proton Collisions at $\sqrt{s}
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Total Pages: 48
Release: 2015
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Our search for pair production of first and second generation leptoquarks is performed in final states containing either two charged leptons and two jets, or one charged lepton, one neutrino and two jets, using proton-proton collision data at √s = 8 TeV. The data, corresponding to an integrated luminosity of 19.7 fb-1, were recorded with the CMS detector at the LHC. First-generation scalar leptoquarks with masses less than 1010 (850) GeV are excluded for [beta] = 1.0 (0.5), where b is the branching fraction of a leptoquark decaying to a charged lepton and a quark. Similarly, secondgeneration scalar leptoquarks with masses less than 1080 (760) GeV are excluded for [beta] = 1.0 (0.5). Furthermore, mass limits are also set for vector leptoquark production scenarios with anomalous vector couplings, and for R-parity violating supersymmetric scenarios of top squark pair production resulting in similar final-state signatures. These are the most stringent limits placed on the masses of leptoquarks and RPV top squarks to date.

Search for First-generation Scalar Leptoquarks in P Anti-p Collisions at S**(1/2)

Search for First-generation Scalar Leptoquarks in P Anti-p Collisions at S**(1/2)
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Total Pages: 8
Release: 2005
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We report on a search for pair production of first-generation scalar leptoquarks (LQ) in pp collisions at √(s)=1.96 TeV using an integrated luminosity of 203 pb−1 collected at the Fermilab Tevatron collider by the CDF experiment. We observe no evidence for LQ production in the topologies arising from LQLQ→eqeq and LQLQ→eq?q, and derive 95% C.L. upper limits on the LQ production cross section. The results are combined with those obtained from a separately reported CDF search in the topology arising from LQLQ→?q?q and 95% C.L. lower limits on the LQ mass as a function of ?=BR(LQ→eq) are derived. The limits are 236, 205 and 145 GeV/c2 for ?=1, ?=0.5 and ?=0.1, respectively.

Search for Pair Production of Third-generation Scalar Leptoquarks and Top Squarks in Proton-proton Collisions at [arrow]"

Search for Pair Production of Third-generation Scalar Leptoquarks and Top Squarks in Proton-proton Collisions at [arrow]
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Total Pages: 21
Release: 2014
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A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.7 fb-1, collected with the CMS detector at the LHC with [arrow]" = 8 TeV. The number of observed events is found to be in agreement with the expected standard model background. Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, assuming a 100% branching fraction for the leptoquark decay to a tau lepton and a bottom quark. In addition, this mass limit applies directly to top squarks decaying via an R-parity violating coupling [lambda]'333. The search also considers a similar signature from top squarks undergoing a chargino-mediated decay involving the R-parity violating coupling [lambda]'3jk. Each top squark decays to a tau lepton, a bottom quark, and two light quarks. Top squarks in this model with masses below 580 GeV are excluded at 95% confidence level. The constraint on the leptoquark mass is the most stringent to date, and this is the first search for top squarks decaying via [lambda]'3jk.

Search for Third-Generation Scalar Leptoquarks in the T$\tau$ Channel in Proton-Proton Collisions at $\sqrt{s}$

Search for Third-Generation Scalar Leptoquarks in the T$\tau$ Channel in Proton-Proton Collisions at $\sqrt{s}$
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Total Pages: 41
Release: 2015
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A search for pair production of third-generation scalar leptoquarks decaying to top quark and $\tau$ lepton pairs is presented using proton-proton collision data at a center-of-mass energy of $\sqrt{s}$ = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb-1. The search is performed using events that contain an electron or a muon, a hadronically decaying $\tau$ lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a $\tau$ lepton, the existence of pair produced, charge -1/3, third-generation leptoquarks up to a mass of 685 GeV is excluded at 95% confidence level. This result constitutes the first direct limit for leptoquarks decaying into a top quark and a $\tau$ lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling [lambda]' 333.