v 1 2 1 M ar 1 99 4 SWAT / 27 STRONG EXTENDED TECHNICOLOUR INTERACTIONS AND THE Zbb̄ VERTEX
نویسنده
چکیده
LEP precision measurements of the Zb ¯ b vertex coupling are sufficiently accurate to see the non-oblique corrections from the heavy gauge boson responsible for the large top mass in standard extended tecnicolour models. If the ETC couplings are strong the techni-fermion condensate may be enhanced by several orders of magnitude allowing a top mass of order 150GeV to be obtained for large values of the ETC breaking scale sufficient to supress the ETC contribution to the Zb ¯ b vertex. In this letter we investigate the degree of fine tuning of the ETC coupling required in a realistic model. We conclude that the fine tuning need only be of order 10%.
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