Tests of non-standard electroweak couplings of right-handed quarks

TL;DR

This paper investigates non-standard electroweak couplings of right-handed quarks within a systematic effective theory framework, analyzing experimental constraints and implications for light quark interactions.

Contribution

It introduces a minimal Low-Energy Effective Theory with non-standard fermion couplings, providing a comprehensive NLO analysis of experimental constraints.

Findings

Modified couplings of right-handed quarks to Z boson identified

Emergence of direct right-handed quark-W couplings

Constraints on non-standard couplings from experimental data

Abstract

The standard model can be interpreted as the leading order of a Low-Energy Effective Theory (LEET) invariant under a higher non linearly realized symmetry $S_{nat}\supset SU(2)_W \times U(1)_Y$ equipped with a systematic power counting. Within the minimal version of this ``not quite decoupling'' LEET, the dominant non-standard effect appears at next-to-leading order (NLO) and is a modification of the couplings of fermions to W and Z. In particular, the coupling of right-handed quarks to Z is modified and a direct coupling of right-handed quarks to W emerges. Charged right-handed lepton currents are forbidden by an additional discrete symmetry in the lepton sector originally designed to suppress Dirac neutrino masses. A complete NLO analysis of experimental constraints on these modified couplings is presented. Concerning couplings of light quarks, the interface of the electroweak tests with QCD aspects is discussed in detail.