Measurement of the top quark mass in the dilepton channel using mT2 at CDF

We present measurements of the top quark mass using m T2 , a variable related to the transverse mass in events with two missing particles. We use the template method applied to tt dilepton events produced in p p collisions at Fermilab's Tevatron Collider and collected by the CDF detector. From a data sample corresponding to an integrated luminosity of 3.4 fb -1 , we select 236 tt candidate events. Using the m T2 distribution, we measure the top quark mass to be M top = 168.0 +4.8 -4.0 (stat) ± 2.9(syst) GeV/c 2 . By combining m T2 with the reconstructed top quark mass distributions based on a neutrino weighting method, we measure M top = 169.3 ± 2.7(stat) ± 3.2(syst) GeV/c 2 . This is the first application of the m T2 variable in a mass measurement at a hadron collider.