Final-State Interactions in e^+e^- -> t\bar{t} -> b l^+ \nu \bar{b} W^- Near Top Quark Threshold
Abstract
We calculate final-state interaction corrections to the energy-angular distribution of l^+ in semi-leptonic top quark decay, where the parent top quark is produced via e^+e^- -> t\bar{t} near threshold. These are the corrections due to gluon exchange between t and \bar{b} (\bar{t} and b) and between b and \bar{b}. Combining with previously known other corrections, we explicitly write down the l^+ energy-angular distribution including the full O(alpha_s)=O(beta) corrections near t\bar{t} threshold. Numerical analyses of the final-state interaction corrections are given. We find that they deform the l^+ distribution typically at the 10% level. We also find that all qualitative features of the numerical results can be understood from intuitive pictures. The mechanisms of various effects of the final-state interactions are elucidated. Finally we define an observable which is proper to the decay process of the top quark (dependent only on d\Gamma_{t -> b l^+ \nu}/ dE_l d\Omega_l of a free polarized top quark) near t\bar{t} threshold. Such a quantity will be useful in extracting the decay property of the top quark using the highly polarized top quark samples.
Cite
@article{arxiv.hep-ph/9708223,
title = {Final-State Interactions in e^+e^- -> t\bar{t} -> b l^+ \nu \bar{b} W^- Near Top Quark Threshold},
author = {M. Peter and Y. Sumino},
journal= {arXiv preprint arXiv:hep-ph/9708223},
year = {2016}
}
Comments
Section 6 is enlarged substantially and a paragraph is added to Section 8 correspondingly. Reference list is also improved. (27 pages including figures, LaTeX)