Abstract
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 s=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 λ333′. The search also considers a similar signature from top squarks undergoing a chargino-mediated decay involving the R-parity violating coupling λ3jk′. 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 λ3jk′.
Highlights
Many extensions of the standard model (SM) predict new scalar or vector bosons, called leptoquarks (LQ), which carry non-zero lepton and baryon numbers, as well as color and fractional electric charge
Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, assuming a 100%
The symbol MLQ is used for the leptoquark mass and the symbol Mt is used for the top squark mass
Summary
Many extensions of the standard model (SM) predict new scalar or vector bosons, called leptoquarks (LQ), which carry non-zero lepton and baryon numbers, as well as color and fractional electric charge. The decay of the sneutrino occurs according to an RPV operator with a coupling constant λ′3 jk, where the cases j, k = 1, 2 are considered Such signal models can only be probed by searches that do not require large missing transverse momentum, as the other decay of the chargino, χ ± → ντ , does not contribute to scenarios involving the λ′3 jk coupling because of chiral suppression. From such a signal process, we expect events with two tau leptons, two jets originating from hadronization of the bottom quarks, and at least four additional jets. This Letter presents the first search for the chargino-mediated decay of the top squark through the RPV coupling λ′3 jk
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