Z-COUPLINGS TO PSEUDO-GOLDSTONE BOSONS WITHIN EXTENDED TECHNICOLOR

The couplings of the Z to pseudo-Goldstone particles occuring within technicolor theories are examined using the chiral lagrangian technique. Particular attention is paid to the effects of the four-technifermion interactions of extended technicolor. Interactions of this type can give the pseudo-Goldstone bosons their masses and also can induce couplings of the form ZμZμP0, Zμ(P0∂μP0′-P0′∂μP0) and ZμWμP. We show however that none of the four-Fermi interactions which induce the neutral pseudo-Goldstone ZμZμP0 couplings contribute to the average mass squared of the pseudo-Goldstone bosons to first order, so that these couplings can be appreciable even for light pseudo-Goldstone bosons. The ZμZμP0 couplings are Higgs-like but for symmetry reasons cannot occur in pure technicolor models without four-technifermion interactions. The Zμ(P0∂μP0′-P0′∂μP0) couplings are also Higgs-like, and unless unusual hypercharge assignments are given to the technifermions, they too are forbidden in the absence of four-technifermion interactions. When these four-Fermi couplings are taken into account, the above vertices can occur, and there exists the possibility that they can approach strengths comparable to their standard Higgs counterparts in models where the number of technifermion flavors is reasonably large. This can make the experimental differentiation of pseudo-Goldstone particles from Higgs particles more difficult. The vertex ZμWμP is notably not Higgs-like and therefore we have found it relevant also to study this coupling. © 1990.