Bounds from tt production on R-parity violating models of supersymmetry

We study tt production in R-parity violating supersymmetry. The annihilation channel qq → tt gets new contributions from t-channel exchange of squarks or sleptons. With the data from Tevatron on tt production, we find that the squarkor slepton-exchange processes constrain the B-violating λ″ couplings or the L-violating λ′ couplings, respectively. In the relevant region of the MSSM parameter space, our bounds are already comparable to the few existing constraints on third-generation R-parity violating couplings, and will improve when more precise measurements of the tt production cross-section become available. We also discuss the effects of these couplings for top production at the LHC.