The Effects on $S$, $T$, and $U$ from Higher-Dimensional Fermion Representations

Zhang, Hong-Hao; Cao, Yue; Wang, Qing

The Effects on $S$, $T$, and $U$ from Higher-Dimensional Fermion Representations

Authors

Zhang, Hong-Hao

Cao, Yue

Wang, Qing

Description

Inspired by a new class of walking technicolor models recently proposed using higher-dimensional technifermions, we consider the oblique corrections from heavy non-degenerate fermions with two classes of higher-dimensional representations of the electroweak gauge group itself. One is chiral SM-like, and the other is vector-like. In both cases, we obtain explicit expressions for $S$, $T$, $U$ in terms of the fermion masses. We find that to keep the $T$ parameter ultraviolet-finite there must be a stringent constraint on the mass non-degeneracy of a heavy fermion multiplet.
4 pages