Model-independent measurement of the $W$ boson helicity in top quark decays at D0
Phys.Rev.Lett. 100 (2008) 062004, 2008.
The collaboration

Abstract (data abstract)
Fermilab-Tevatron. Model-independent measurement of the helicity of W bosons produced in top quark decays. The data come from TOP TOPBAR events produced in PBAR P interactions at a centre-of-mass energey of 1960 GeV and have a total integrated luminosity of 1 fb-1. The COS(THETA*) distributions are presented where THETA* is the angle between the momenta of the down-type fermion and the top quark in the W boson rest frame, referred to here as RF=WTOP. Data are given for the the leptonic decaying W in both lepton-jets and dilepton events and for the hadronic decaying W in lepton jet events.. Also included in this records are PRELIMINARY data for the 2008 conferences taken from the D0 Note 5772-CONF based on 2.7 fb-1 of data.