arXiv:1005.2625·v1·High Energy Physics — Phenomenology
Helicity fractions of W bosons from top quark decays at NNLO in QCD
Andrzej Czarnecki🇨🇦 · Jurgen G. Korner🇩🇪 · Jan H. Piclum🇨🇦
Abstract
Decay rates of unpolarized top quarks into longitudinally and transversally polarized W bosons are calculated to second order in the strong coupling constant alpha_s. Including the finite bottom quark mass and electroweak effects, the Standard Model predictions for the W boson helicity fractions are F_L=0.687(5), F_+=0.0017(1), and F_-=0.311(5).
Comments: 5 pages, 1 figure