Matthew Reece, Cornell University
Constraints on the S-parameter in Technicolor
September 19, 2007

It is well known that QCD-like technicolor dynamics produces a large
positive S parameter, whereas precision electroweak measurements
favor a small S parameter. Recently it has been suggested that
"holographic technicolor" models in extra dimensions can have
negative S. I will discuss work done in collaboration with Kaustubh
Agashe, Csaba Csaki, and Christophe Grojean, arguing that calculable,
unitary 5D models in fact necessarily have positive S. Attempts to
drive S negative with higher-dimension operators lead to ghosts. I
will also sketch some general arguments that suggest that positive S
may be a feature of all custodially symmetric models of technicolor.