Download or read book Model-independent Measurement of the W Boson Helicity in Top Quark Decays at written by and published by . This book was released on 2007 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb−1 sample of candidate t{bar t} events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider. We reconstruct the angle [theta]* between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos [theta]* distribution finds that the fraction of longitudinal W bosons f0 = 0.390 ± 0.177 (stat.) ± 0.104 (syst.) and the fraction of right-handed W bosons f+ = 0.171 ± 0.102 (stat.) ± 0.058 (syst.), which is consistent at the 27% C.L. with the standard model.