Reexamination of the Constraint on Topcolor-Assisted Technicolor Models from R_b
Abstract
Recent study on the charged top-pion correction to R_b shows that it is negative and large, so that the precision experimental value of R_b gives rise to a severe constraint on the topcolor-assisted technicolor models such that the top-pion mass should be of the order of 1 TeV. In this paper, we restudy this constraint by further taking account the extended technicolor gauge boson correction which is positive. With this positive contribution to R_b, the constraint on the topcolor-assisted technicolor models from R_b changes significantly. The top-pion mass is allowed to be in the region of a few hundred GeV depending on the models.
Keywords
Cite
@article{arxiv.hep-ph/0001133,
title = {Reexamination of the Constraint on Topcolor-Assisted Technicolor Models from R_b},
author = {Chongxing Yue and Yu-Ping Kuang and Xue-Lei Wang and Weibin Li},
journal= {arXiv preprint arXiv:hep-ph/0001133},
year = {2011}
}
Comments
6-page RevTex file using epsfig.sty for the insertion of the three figures. Discussion on the oblique correction parameter T is added. Version for publication in Phys. Rev. D