Search

Neutral flavor-changing transitions are hugely suppressed in the Standard Model and therefore they are very sensitive to new physics. We consider the decay rate of t → uih where ui = u,c using an effective field theory approach. We perform the calculation at next-to-leading order (NLO) in QCD including the relevant dimension-six operators. We find that at NLO the contribution from the flavor-changing chromomagnetic operator is as important as the standard QCD correction to the flavor-changing Yukawa coupling. In addition to improving the accuracy of the theoretical predictions, the NLO calculation provides information on the operator mixing under the renormalization group. [ABSTRACT FROM AUTHOR]

We discuss new physics in top-quark interactions, using an effective-field-theory approach. We consider top-quark decay, single top production, and top-quark pair production. We identify 15 dimension-six operators that contribute to these processes, and we compute the deviation from the standard model induced by these operators. The results provide a systematic way of searching for (or obtaining bounds on) physics beyond the standard model. [ABSTRACT FROM AUTHOR]