Supersymmetric effects in top quark decay into polarizedWboson

Abstract

We investigate the one-loop supersymmetric QCD ͑SUSY-QCD͒ and electroweak ͑SUSY-EW͒ corrections to the top quark decay into a b quark and a longitudinal or transverse W boson. The corrections are presented in terms of the longitudinal ratio ⌫(t→W L b)/⌫(t→Wb) and the transverse ratio ⌫(t→W Ϫ b)/⌫(t→Wb). In most of the parameter space, both SUSY-QCD and SUSY-EW corrections to these ratios are found to be less than 1% in magnitude and they tend to have opposite signs. The corrections to the total width ⌫(t→Wb) are also presented for comparison with the existing results in the literature. We find that our SUSY-EW corrections to the total width differ significantly from previous studies: the previous studies give a large correction of more than 10% in magnitude for a large part of the parameter space while our results reach only few percent at most.

Noncommutative standard model in the top quark sector

“…For instance, the non-standard effects on the full top width have been investigated in the minimal supersymmetric standard model and in the technicolor model [3], [4], [5], [6], [7]. Some studies have been performed on the effects of anomalous tW b couplings on the top width and some constraints have been applied on the anomalous couplings [8], [9], [10], [11], [12], [13].…”

Measurements of the production, decay and properties of the top quark: a review

“…According to the SM, the V-A structure of the W tb vertex leads to the prediction that the W -boson helicity in top decays will be 69.8 % longitudinal, 30.1 % left-handed, and 0.041 % right-handed [118][119][120][121]. Any deviation from these expected values would be a sign of new physics modifying the W tb vertex.…”

Effects of R-parity violation in unpolarized top quark decay into a polarized W boson

“…So far theoretical predictions of these observables reported in the literatures are summarized as follows: the QCD corrections to the top width are rather large in general. One-loop QCD corrections to treelevel width are ÿ8:54% [3][4][5][6][7][8], one-loop electroweak corrections are 1:54% [3,9,10] and two-loop QCD corrections are approximate ÿ2:05% [11] ( ÿ 2:16% [12] ), and the one-loop SUSY-QCD and SUSY-EW corrections are below 1% in magnitude for most of the parameter space [13]. As for the partial longitudinal and transverse rates, for the top quark mass m t 175 GeV, the tree-level results are 0.703 for ÿ L =ÿ, 0.297 for ÿ ÿ =ÿ and O10 ÿ4 for ÿ =ÿ, respectively.…”