Measurement of the $W$ boson helicity fractions in $t\overline{t}$ production in dilepton channel at CDF

We analyze $W$ boson helicity fractions of $t\overline{t}$ candidates selected from final states where both $W$ bosons are decaying leptonically. The analysis is based on 3~fb$^{-1}$ of data collected with the CDF detector at the Tevatron. The $W$ helicity fractions are determined by a comparison of angular distributions of leptons in the $W$ rest-frame with templates corresponding to left-handed, right-handed and longitudinal fractions exclusively. This is the first measurement of $W$ helicity fractions in this channel using kinematic reconstruction at CDF.