Summing logarithms and factorization for massive quark initiated jets and the Pythia top quark mass
October 06, 2016
The most precise top quark mass measurements use kinematic reconstruction methods, determining the top mass parameter of a Monte Carlo event generator, m_t^MC. Due to the complicated interplay of hadronization and parton shower dynamics in Monte Carlo event generators, relating m_t^MC to field theory masses is a non-trivial task. In this talk we present a calibration procedure to determine this relation using hadron level QCD predictions for 2-Jettiness in e^+e^- annihilation, an observable which has kinematic top mass sensitivity and has a close relation to the invariant mass of the particles coming from the top decay. The theoretical ingredients of the QCD prediction are explained. Fitting e^+e^- 2-Jettiness calculations at NLL/NNLL order to Pythia 8.205, we find that
m_t^MC agrees with the MSR mass at the scale 1 GeV within uncertainties, m_t^MC ~ m_t^MSR(1 GeV), but differs from the pole mass by 900/600 MeV.
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