title: Measurement of the helicity of W bosons in top quark decays
abstract: We use the transverse momentum spectrum of leptons in the decay chain t-->bW with W-->lnu to measure the helicity of the W bosons in the top quark rest frame. Our measurement uses a t&tmacr; sample isolated in 106+/-4 pb(-1) of data collected in p&pmacr; collisions at sqrt[s] = 1.8 TeV with the CDF detector at the Fermilab Tevatron. Assuming a standard V-A weak decay, we find that the fraction of W's with zero helicity in the top rest frame is F0 = 0.91+/-0. 37(stat)+/-0.13(syst), consistent with the standard model prediction of F0 = 0.70 for a top mass of 175 GeV/c(2).
authors.affiliation: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.initials: F
authors.lastname: Ukegawa
authors.initials: J
authors.lastname: Valls
authors.initials: S
authors.lastname: Vejcik
authors.initials: G
authors.lastname: Velev
authors.initials: R
authors.lastname: Vidal
authors.initials: R
authors.lastname: Vilar
authors.initials: I
authors.lastname: Vologouev
authors.initials: D
authors.lastname: Vucinic
authors.initials: RG
authors.lastname: Wagner
authors.initials: RL
authors.lastname: Wagner
authors.initials: J
authors.lastname: Wahl
authors.initials: NB
authors.lastname: Wallace
authors.initials: AM
authors.lastname: Walsh
authors.initials: C
authors.lastname: Wang
authors.initials: CH
authors.lastname: Wang
authors.initials: MJ
authors.lastname: Wang
authors.initials: T
authors.lastname: Watanabe
authors.initials: T
authors.lastname: Watts
authors.initials: R
authors.lastname: Webb
authors.initials: H
authors.lastname: Wenzel
authors.initials: WC
authors.lastname: Wester
authors.initials: AB
authors.lastname: Wicklund
authors.initials: E
authors.lastname: Wicklund
authors.initials: HH
authors.lastname: Williams
authors.initials: P
authors.lastname: Wilson
authors.initials: BL
authors.lastname: Winer