Orateur
Prof.
Svjetlana Fajfer
(Institute Jozef Stefan and Ljubljana University)
Description
The most general new physics effective operators in the decay of an unpolarized top quark into a bottom quark and a W gauge boson are considered at next-to-leading order in QCD. We find that the dipole operator O_{LR} contribution to the transverse-plus W helicity fraction F_+ is significantly enhanced compared to the leading order result at non-vanishing bottom quark mass. Nonetheless, presently the most sensitive observable to direct O_{LR} contributions is the longitudinal W helicity fraction F_L. In particular, the most recent CDF measurement of F_L already provides the most stringent upper bound on O_{LR} contributions, even when compared with indirect bounds from the rare decay B -> X_s gamma.
Auteur principal
Prof.
Svjetlana Fajfer
(Institute Jozef Stefan and Ljubljana University)
Co-auteurs
Dr
Jernej Fesel Kamenik
(Institute Jozef Stefan and Ljubljana University)
M.
Jure Drobnak
(Institute Jozef Stefan)
