Measurement of the top quark mass at CDF using the “neutrino ϕ weighting” template method on a lepton plus isolated track sample

Résumé fourni par la source

We present a measurement of the top quark mass with $t\overline{t}$ dilepton events produced in $p\overline{p}$ collisions at the Fermilab Tevatron ($\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$) 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 $2.9\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, are selected as $t\overline{t}$ candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles $({\ensuremath{\phi}}_{{\ensuremath{\nu}}_{1}},{\ensuremath{\phi}}_{{\ensuremath{\nu}}_{2}})$ of neutrinos and reconstruct the top quark mass for each ${\ensuremath{\phi}}_{{\ensuremath{\nu}}_{1}}$, ${\ensuremath{\phi}}_{{\ensuremath{\nu}}_{2}}$ pair by minimizing a ${\ensuremath{\chi}}^{2}$ function in the $t\overline{t}$ dilepton hypothesis. We assign ${\ensuremath{\chi}}^{2}$-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated $t\overline{t}$ and background events, and parametrized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of ${165.5}_{\ensuremath{-}3.3}^{+3.4}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}3.1(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.