Impact of FCNC top quark interactions on BR(t -> b W)

TL;DR

This paper investigates how flavor-changing neutral current interactions of the top quark influence its decay branching ratios, using experimental data to set stringent bounds on these rare processes.

Contribution

The study provides the first comprehensive analysis combining Tevatron and B-factory data to constrain FCNC top quark decay branching ratios under the assumption of CKM unitarity.

Findings

Br(t -> q X) < 4.0 x 10^{-4} for any vector boson X

Stringent bounds derived from combined experimental data

Analysis assumes CKM matrix unitarity

Abstract

We study the effect that FCNC interactions of the top quark will have on the branching ratio of charged decays of the top quark. We have performed an integrated analysis using Tevatron and B-factories data and with just the further assumption that the CKM matrix is unitary we can obtain very restrictive bounds on the strong and electroweak FCNC branching ratios Br(t -> q X) < 4.0 10^{-4}, where X is any vector boson and a sum in q = u,c is implied.