t bar t production rates at the Fermilab Tevatron and the CERN LHC in top-color-assisted multiscale technicolor models

We study the contributions of the neutral pseudo Goldstone bosons (technipions and top pions) to the t bar t production cross sections at the Fermilab Tevatron and the CERN LHC in top-color-assisted multiscale technicolor (TOPCMTC) models via the gluon-gluon fusion process from the loop-level couplings between the pseudo Goldstone bosons and the gluons. The MRS set A' parton distributions are used in the calculation. It is shown that the new CDF datum on the t bar t production cross section gives constraints on the parameters in the TOPCMTC models. Models with a large portion of technicolor contributed top-quark mass are disfavored. With reasonable values of the parameters in TOPCMTC models, the cross section at the Tevatron is larger than that predicted by the standard model, and is consistent with the new CDF data. The enhancement of the cross section and the resonance peaks at the LHC are more significant, so that it is testable in future experiments. copyright 1997 The American Physical Society