Optimal determination of New Physics couplings: A comparative study

TL;DR

This paper compares optimal observable techniques and standard analysis methods for determining new physics couplings in collider experiments, focusing on scenarios where either the Standard Model or new physics dominates.

Contribution

It extends the optimal observable technique to different dominance regimes and compares its effectiveness with traditional chi-squared analysis in collider settings.

Findings

Optimal observable method provides more precise NP parameter estimates.

Background reduction and beam polarization significantly improve measurement accuracy.

Comparison shows advantages of optimal observables over standard chi-squared analysis.

Abstract

We study the determination of new physics (NP) parameters using the optimal observable technique (OOT) in situations where the standard model (SM) dominates over the NP effects, and when the NP dominates over the SM contribution, using the 2-Higgs doublet model as an illustrative example; for the case of SM domination we extend our results using an effective theory parameterization of NP effects. For the case of SM dominance we concentrate on $t \bar{t}$ production in an $e^+e^-$ collider, while for the case of NP dominance we consider both $t \bar{t}$ production and pair production of charged scalars, also in an $e^+e^-$ collider. We discuss the effects of the efficiency of background reduction, luminosity and beam polarization, and provide a comparison of the optimal uncertainties with those obtained using a standard $\chi^2$ analysis of (Monte Carlo generated) collider data.