Electroweak Chiral Lagrangian from Natural Topcolor-assisted Technicolor Model

TL;DR

This paper extends previous calculations of the electroweak chiral Lagrangian coefficients to Lane's natural topcolor-assisted technicolor model, revealing similar features to Hill's model but with smaller technicolor groups and Z' masses, and providing detailed coefficient values.

Contribution

It generalizes the computation of electroweak chiral Lagrangian coefficients to Lane's model, highlighting key differences and detailed parameter values.

Findings

Lane's model has similar features to Hill's model.

Z' mass must be smaller than 400 GeV.

S parameter is around +1 due to three doublets of techniquarks.

Abstract

Based on previous studies computing coefficients of the electroweak chiral Lagrangian from C.T.Hill's schematic topcolor-assisted technicolor model, we generalize the calculation to K.Lane's prototype natural topcolor-assisted technicolor model. We find that typical features of the model are qualitatively similar as those of Hill's model, but Lane's model prefers smaller technicolor group and Z' mass must be smaller than 400GeV, further S parameter is around order of +1 mainly due to existence of three doublets of techniquarks. We obtain the values for all coefficients of the electroweak chiral Lagrangian up to order of p^4. Apart from negative large four fermion coupling values, ETC impacts on the electroweak chiral Lagrangian coefficients are small, since techniquark self energy which determines these coefficients in general receives almost no influence from ETC induced four fermion interactions except for its large momentum tail.