Bottom-flavored hadrons from top-quark decay at next-to-leading order in the general-mass variable-flavor-number scheme

Abstract

We study the scaled-energy (xB) distribution of bottom-flavored hadrons (B) inclusively produced in top-quark decays at next-to-leading order (NLO) in the general-mass variable-flavor-number scheme endowed with realistic, nonperturbative fragmentation functions that are obtained through a global fit to e+e− data from CERN LEP1 and SLAC SLC exploiting their universality and scaling violations. Specifically, we study the effects of gluon fragmentation and finite bottom-quark and B-hadron masses. We find the NLO corrections to be significant. Gluon fragmentation leads to an appreciable reduction in the partial decay width at low values of xB. Hadron masses are responsible for the low-xB threshold, while the bottom-quark mass is of minor importance. Neglecting the latter, we also study the doubly differential distribution d2Γ/(dxBdcosθ) of the partial width of the decay t→bW+→Bℓ+νℓ+X, where θ is the decay angle of the charged lepton in the W-boson rest frame.