20-27 July 2011
Alpes Congrès - Alpexpo
Europe/Paris timezone

QCD effects and search for new physics in t−>bW

21 Jul 2011, 17:15
Bayard (Alpes Congrès - Alpexpo)


Alpes Congrès - Alpexpo

Parallel session talk QCD QCD


Prof. Svjetlana Fajfer (Institute Jozef Stefan and Ljubljana University)


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.

Primary author

Prof. Svjetlana Fajfer (Institute Jozef Stefan and Ljubljana University)


Dr Jernej Fesel Kamenik (Institute Jozef Stefan and Ljubljana University) Mr Jure Drobnak (Institute Jozef Stefan)

Presentation Materials