Search for R-parity violating decays of a top squark in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This paper reports a search for R-parity violating decays of top squarks in proton-proton collisions at 8 TeV, setting new mass exclusion limits and finding no deviation from the standard model.

Contribution

It presents the first exclusion limits on top squark masses in R-parity violating models with specific decay channels at 8 TeV.

Findings

Excluded top squark masses below 890 GeV (electron channel) and 1000 GeV (muon channel).

No significant excess observed over standard model predictions.

Set upper limits on top squark pair production cross sections at 95% confidence level.

Abstract

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.