New Hints for Testing Anomalous Top-Quark Interactions at Future Linear Colliders

TL;DR

This paper investigates how angular and energy distributions of leptons and bottom quarks in top-quark pair production at future linear colliders can reveal anomalous top-quark interactions, highlighting the insensitivity of certain distributions to non-standard Wtb couplings.

Contribution

It provides a comprehensive calculation of decay product distributions considering the most general top-quark couplings, revealing which observables are sensitive or insensitive to new physics.

Findings

Leptonic angular distribution is insensitive to non-standard Wtb vertex.

Energy and angular dependence factorization persists even with anomalous couplings.

Standard Model distributions are preserved despite deviations in decay vertices.

Abstract

Angular and energy distributions for leptons and bottom quarks in the process e^+e^- --> t t-bar --> l^{+-}/b(b-bar) ... have been calculated assuming the most general top-quark couplings. The double distributions depend both on modification of the t t-bar production and t(t-bar) --> b(b-bar) W decay vertices. However, the leptonic angular distribution turned out to be totally insensitive to non-standard parts of Wtb vertex. Distributions of decay products for polarized top quark in its rest frame have been also calculated. It has been found that the factorization of energy and angular dependence for the double leptonic distribution noticed earlier for the Standard Model survives even if one allows for deviations from the V-A interactions, and the SM angular leptonic distribution turned out to be preserved by anomalous decay vertex.