Future Colliders

Abstract:

We present a measurement of the top quark mass in the lepton+jets and dilepton channels of tt̄ decays using the data sample corresponding to an integrated luminosity of 5.6fb-1 of pp̄ collisions at Tevatron with √s=1.96TeV, collected with the CDF II detector. We construct templates of two reconstructed top quark masses from different jets-to-quarks combinations and the invariant mass of two jets from the W decays in the lepton+jets channel, and a reconstructed top quark mass and mT2, a variable related to the transverse mass in events with two missing particles, in the dilepton channel. The simultaneous fit of the templates from signal and background events in the lepton+jets and dilepton channels to the data yields a measured top quark mass of Mtop=172.1±1.1(stat)±0. 9(syst)GeV/c2. © 2011 American Physical Society.

Abstract:

We present a comment on the kinematic variable mCT2 recently proposed in Won Sang Cho, Jihn E. Kim, and Ji-Hun Kim, Phys. Rev. D 81, 095010 (2010). The variable is designed to be applied to models such as R-parity conserving supersymmetry (SUSY) when there is pair production of new heavy particles each of which decays to a single massless visible and a massive invisible component. It was proposed by Cho, Kim, and Kim that a measurement of the peak of the mCT2 distribution could be used to precisely constrain the masses of the SUSY particles. We show that, for the an example characterized by direct squark decays, when standard model backgrounds are included in simulations, the sensitivity of the mCT2 variable to the SUSY particle masses is more seriously impacted for mCT2 than for other previously proposed variables. © 2011 American Physical Society.