Neutral top-pion and top-charm production in high energy e+e−e^{+}e^{-} collisions

We calculate the contributions of the neutral top-pion, predicted by topcolor-assisted technicolor (TC2) theory, to top-charm production via the processes $\gamma\gamma \longrightarrow\bar{t}c$ and $e^{+}e^{-}\longrightarrow \gamma\gamma\longrightarrow \bar{t}c$ at the high energy linear $e^{+}e^{-}$ collider (LC) experiments. The cross section is of order $10^{-2}pb$ in most of the parameter space of TC2 theory, which may be detected at the LC experiments. So the process $e^{+}e^{-}\longrightarrow \bar{t}c$ can be used to detect the signature of TC2 theory.Comment: Latex file, 8 pages with 4 eps figures. to be published Phys.Lett.

Probing neutral top-pion via a flavor-changing process γγ→tcˉΠt0\gamma\gamma\to t\bar{c}\Pi_{t}^{0}

In the framework of topcolor-assisted-technicolor model(TC2), we study a flavor-changing neutral top-pion production process $\gamma\gamma\to t\bar{c}\Pi_{t}^{0}$. The study shows that there exists a resonance effect which can enhance the cross section up to a few fb even tens fb. For a yearly luminosity 100 $fb^{-1}$ at future linear colliders, there might be hundreds even thousands events to be produced. On the other hand, the background of such flavor-changing process is very clean due to the GIM mechanism in SM . With such sufficient events and clean background, neutral toppion could be detected at future linear colliders with high center of energy and luminosity. Our study provides a possible way to test TC2 model.Comment: 10 pages, 4 figures,has been accepted by Phys.Rev.

Testing Technicolor Models in Top Quark Pair Production at High Energy Photon Colliders

We study pseudo-Goldstone boson corrections to top quark pair production rates in technicolor models with and without topcolor at the E=0.5 teV and 1.5 TeV photon colliders. We find that, for reasonable ranges of the parameters, the corrections are large enough to be observable, and the corrections in models with topcolor are considerably larger than those in models without topcolor, and they are all significantly larger than the corresponding corrections in the minimal supersymmetric standard model (MSSM) with tan(beta) of the order of 1. So that the two kinds of technicolor models and the MSSM with tan(beta) of the order of 1 can be experimentally distinguished.Comment: Version for publication in Phys.Rev.D with some references and discussions added and some typos correcte