Anomalous W^+ W^- t {\bar t} Couplings at the e^+ e^- Linear Collider

Abstract

We study production of t {\bar t} via W^+ W^- fusion, including the relevant backgrounds at the proposed Linear Collider (an e^+ e^- collider with \sqrt{S} = 1.5 TeV) in the context of a Higssless Standard Model (SM), i.e. a nonlinear SU(2)_L \times U(1)_Y chiral Lagrangian, including dimension five W^+ W^- t {\bar t} interactions. Deviation from the SM total cross section can be used to constrain the coefficients of these operators to an order of 2 \times 10^{-1} (divided by the cut-off scale Λ= 3.1 TeV) with a 95% C.L.. However, there are three ways in which this sensitivity can be improved by a factor of two. First, by studying the deviation of the t {\bar t} kinematics from what is predicted by the SM; second, by polarizing the collider electron beam; and third, by studying the polarization of the produced top quarks. In this way, we show that it is also possible to attempt to dis-entangle the contributions from different anomalous operators, isolating the form of new physics contributions.