Sextet Quark Physics at the Tevatron ?

Abstract

A sextet quark sector of QCD, together with the sextet higgs mechanism, would produce a major change in the strong interaction above the electroweak scale. This change may already be evident in Cosmic Ray physics and, if so, dramatic effects are to be expected at the LHC. In this paper we discuss whether evidence for the sextet sector could be seen at the Tevatron. A major consequence of the connection between QCD and electroweak symmetry breaking is the strong coupling of the pomeron to the electroweak sector. At the Tevatron, the energy is too low to produce vector boson pairs directly via double pomeron exchange, but a number of small cross-section effects could be seen in diffractive, and diffractive related, processes involving $W^{\pm}$ and $Z^0$ vector bosons. Probably, the most important feature that could be decisively established is that the production cross-section for $W^+W^-$ and $Z^0Z^0$ pairs has an anomalous component with event characteristics different from the Standard Model. This would be the first indication of what should become a dominant, very large, cross-section at the LHC. If the sextet quark dynamical mass scale is well above the top quark mass, then the production properties of $W$'s and $Z$'s could be the only new physics visible at the Tevatron scale. If this scale is lower the situation could be more subtle. The observed $t\bar{t}$ events could originate from the $η_6$ - the ``sextet higgs'', even though they can be understood perturbatively. The interpretation of the top quark mass would, however, be different and non-perturbative decay modes should also be seen. A jet excess at large $E_T$ would provide supporting evidence for this picture, since $α_s$ evolution should stop at $E_T \sim$ ``$m_{top}$''.