Model Independent Constraints Among the Wtb, Zbb, and Ztt Couplings
Abstract
Using an effective Lagrangian approach, we perform a model-independent analysis of the interactions among electroweak gauge bosons and the third generation quarks, i.e. the Wtb, Ztt and Zbb couplings. After one imposes the known experimental constraint on the Z bL bL coupling, we show that the electroweak symmetry of the standard model specifies the pattern of deviations of the Z tL tL and W tL bL couplings, independent of underlying new physics scenarios. We study implications of the predicted pattern with data on the single top quark and Ztt associated production processes at the Large Hadron Collider. Such an analysis could in principle allow for a determination of the Wtb coupling without prior knowledge of |Vtb|, which is otherwise difficult to achieve.