  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.
