Search for pair production of third-generation leptoquarks and top squarks in pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper reports a search for third-generation leptoquarks and top squarks decaying into tau leptons and b quarks using 7 TeV proton-proton collision data, setting new exclusion limits on their masses.

Contribution

It provides the most stringent exclusion limits to date on third-generation leptoquark and top squark masses in R-parity-violating supersymmetric models.

Findings

Vector leptoquarks below 760 GeV are excluded.

Scalar leptoquarks below 525 GeV are excluded.

Top squarks below 453 GeV are excluded.

Abstract

Results are presented from a search for the pair production of third-generation scalar and vector leptoquarks, as well as for top squarks in R-parity-violating supersymmetric models. In either scenario, the new, heavy particle decays into a tau lepton and a b quark. The search is based on a data sample of pp collisions at sqrt(s) = 7 TeV, which is collected by the CMS detector at the LHC and corresponds to an integrated luminosity of 4.8 inverse femtobarns. The number of observed events is found to be in agreement with the standard model prediction, and exclusion limits on mass parameters are obtained at the 95% confidence level. Vector leptoquarks with masses below 760 GeV are excluded and, if the branching fraction of the scalar leptoquark decay to a tau lepton and a b quark is assumed to be unity, third-generation scalar leptoquarks with masses below 525 GeV are ruled out. Top squarks with masses below 453 GeV are excluded for a typical benchmark scenario, and limits on the coupling between the top squark, tau lepton, and b quark, lambda'[333] are obtained. These results are the most stringent for these scenarios to date.