  The results of a search for a supersymmetric partner of the top quark (top
squark), pair-produced in proton-proton collisions at sqrt(s) = 8 TeV, are
presented. The search, which focuses on R-parity violating, chargino-mediated
decays of the top squark, is performed in final states with low missing
transverse momentum, two oppositely charged electrons or muons, and at least
five jets. The analysis uses a data sample corresponding to an integrated
luminosity of 19.7 inverse femtobarns collected with the CMS detector at the
LHC in 2012. The data are found to be in agreement with the standard model
expectation, and upper limits are placed on the top squark pair production
cross section at 95% confidence level. Assuming a 100% branching fraction for
the top squark decay chain, top squark to t + chargino, chargino to lepton +
jj, top squark masses less than 890 (1000) GeV for the electron (muon) channel
are excluded for the first time in models with a single nonzero R-parity
violating coupling lambda'[ijk] (i,j,k <= 2), where i,j,k correspond to the
three generations.
