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 — preprints:1997:ttp97-23 [2016/03/15 20:39] (current) Line 1: Line 1: + ====== TTP97-23 Final-State Interactions in e^+e^- \to t\bar t \to bl^+\nu\bar bW^-        Near Top Quark Threshold ====== + + + 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^- \to 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 full O(\alpha_s)=O(\beta) corrections near + threshold.  Numerical analyses of the final-state interaction + corrections are presented.  We find that they deform the l^+ + distribution typically at 10% level.  Also we elucidate mechanisms of + the various effects of the final-state interactions.  We find that all + qualitative features of the numerical results can be understood from + intuitive pictures.  The natures that \bar{b} is emitted preferrably in + the parent \bar{t}'s spin direction and that there is attractive force + between \bar{b} and \bar{t} generate: shift of |p_t|-distribution, + forward-backward asymmetry of t, modification of the top-quark + polarization vector, and energy-angle-correlated deformation of l^+ + distributions. + + + |**M. Peter and Y. Sumino**  | + | {{preprints:1997:ttp97-23.pdf|PDF}} {{preprints:1997:ttp97-23.ps|PostScript}}   | + | |