Measurement of the Top Quark Mass at CDF using the "neutrino phi weighting" Template Method on a Lepton Plus Isolated Track Sample

We present a measurement of the top quark mass with tt-bar dilepton events produced in p anti-p collisions at the Fermilab Tevatron (sqrt s =1.96 TeV) and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb-1, are selected as tt-bar candidates. To account for the unconstructed event kinematics, we scan over the phase space for the azimuthal angles (phi_nu_1, phi_nu_2) of neutrinos and reconstruct the top quark mass by minimizing a chi2 function in the tt-bar dilepton hypothesis. We assign chi2-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated tt-bar and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit of the preferred mass distribution in data to a weighted sum of signal and background probability density functions gives a top quark mass of 165.5+3.4_-3.3(stat.) +/- 3.1(syst.) GeV/c2.