Optimal determination of New Physics couplings with dominant and subdominant Standard Model contribution

Abstract

The accuracy to which new physics (NP) couplings can be determined using the optimal observable technique (OOT) depends on the strength of the Standard Model (SM) contribution. In this work we study this effect in two cases: one where the SM contribution is dominant and another where it is subdominant. For the first we consider t t production in presence of dimension six effective operators and determine the optimal statistical precision to which the Wilson coefficients can be extracted in an e + e − collider. As an example of NP dominance we consider the production of heavy charged scalars in several 2-Higgs multiplet models (with and without right handed neutrino contributions), and again determine the optimal range of statistical uncertainty for the NP couplings. We confirm the expectation that the optimal estimation of NP couplings with minimal SM interference is more precise than those where SM dominates, and discuss the effects of the efficiency of background reduction, luminosity and beam polarization.