Effective electroweak chiral Lagrangian: The matter sector - art. no. 114035

Citation
E. Bagan et al., Effective electroweak chiral Lagrangian: The matter sector - art. no. 114035, PHYS REV D, 6011(11), 1999, pp. 4035
Citations number
87
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW D
ISSN journal
05562821 → ACNP
Volume
6011
Issue
11
Year of publication
1999
Database
ISI
SICI code
0556-2821(199912)6011:11<4035:EECLTM>2.0.ZU;2-P
Abstract
We parametrize in a model-independent way possible departures from the mini mal standard model predictions in the matter sector. We only assume the sym metry breaking pattern of the standard model and that new particles are suf ficiently heavy so that the symmetry is nonlinearly realized. Models with d ynamical symmetry breaking are generically of this type. We review in effec tive theory language to what extent the simplest models of dynamical breaki ng are actually constrained and the assumptions going into the comparison w ith experiment. Dynamical symmetry breaking models can be approximated at i ntermediate energies by four-fermion operators. We present a complete class ification of the latter when new particles appear in the usual representati ons of the SU(2)(L) x SU(3)(c) group as well as a partial classification in the general case. We discuss the accuracy of the four-fermion description by matching to a simple ''fundamental'' theory. The coefficients of the eff ective Lagrangian in the matter sector for dynamical symmetry breaking mode ls (expressed in terms of the coefficients of the four-quark operators) are then compared to those of models with elementary scalars (such as the mini mal standard model). Contrary to a somewhat widespread belief, we see that the sign of the vertex corrections is not fixed in dynamical symmetry break ing models. This work provides the theoretical tools required to analyze, i n a rather general setting, constraints on the matter sector of the standar d model. [S0556-2821(99)05621-0].