Breaking of isospin symmetry in theories with a dynamical Higgs mechanism

Thomas Appelquist, Mark J. Bowick, Eugene Cohler, Avi I. Hauser

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


The sensitivity of physical amplitudes to the observed isospin-symmetry breaking in the fermion mass matrix is analyzed in theories where the electroweak symmetry is dynamically broken. As a first step toward discussing dynamical theories in a model-independent way, we consider a strongly interacting Higgs theory. The nonlinear model coupled to an SU(2)×U(1) Yang-Mills theory and to fermions is used to generate the low-dimensional operators induced by the quantum theory. The strengths of these operators, in particular those that break isospin symmetry, are estimated using the Higgs-boson mass of the linear model as a regulator. Technicolor models are next considered as a specific example of the strong-interaction physics which leads to electroweak symmetry breaking. Emphasis is placed on the effective four-fermion interactions that are natural partners of those which give mass to the ordinary fermions. New sources of isospin-symmetry breaking are found; in particular there is one which contributes directly to the parameter with strength that is linear in the effective Yukawa coupling of the heaviest ordinary fermion. This effect is qualitatively different from the quadratic dependence found in Higgs theories.

Original languageEnglish (US)
Pages (from-to)1676-1684
Number of pages9
JournalPhysical Review D
Issue number7
StatePublished - 1985
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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