Uncertainties on the theoretical input for ttj experimental analyses at the LHC
Abstract
The precise measurement of the top-quark mass constitutes one of the main goals of the LHC top-quark physics program. One possibility to extract this parameter uses the s distribution, which depends on the invariant mass of the ttj system. To fully take advantage of the experimental accuracy achievable in measuring top quark production cross sections at the LHC, the theory uncertainties need to be well under control. We present a study of the effect of varying the input parameters of the theoretical calculation on the predicted s distribution. Thereby we studied the influence of the R parameter in the jet reconstruction procedure, as well as the effect of various renormalization and factorization scale definitions and different PDF sets. A behaviour similar to the one presented here for the s-distribution was also found for other differential distributions.