Search for pair production of third-generation scalar leptoquarks and top squarks in proton-proton collisions at sqrt{s} = 8 TeV

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 inverse femtobarns, collected with the CMS detector at the LHC with
sqrt(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 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].