Detecting and Studying the Lightest Pseudo-Goldstone Boson at Future $pp$, $e^+e^-$ and $μ^+μ^-$ Colliders

For an attractive class of dynamical symmetry breaking (technicolor) models, the lightest neutral pseudo-Nambu-Goldstone boson ($\pzero$) contains only down-type techniquarks and charged technileptons. We discuss the prospects for discovering and studying the $\pzero$ of such models at the Tevatron and the LHC and at future $\epem$ and $\mupmum$ colliders. Discovery of the $\pzero$ at the Tevatron and the LHC in the $gg\to\pzero\to\gam\gam$ mode should be possible over a wide range of mass. Discovery of the $\pzero$ at an $\epem$ collider via the reaction $\epem\to\gam \pzero$ should be possible for an integrated luminosity of $L=100\fbi$ at $\rts=500\gev$ as long as $\mpzero$ is not near $\mz$. However, measuring the branching fractions and couplings of the $\pzero$ with precision would require much more luminosity. In the $\gam\gam$ collider mode of operation at an $\epem$ collider, the $\gam\gam\to\pzero\to b\anti b$ signal will be be very robust. At a $\mupmum$ collider, discovery of the $\pzero$ as an $s$-channel resonance should prove possible via scanning, even if it has not already been detected elsewhere. Once the precise mass of the $\pzero$ is known, operation of the $\mupmum$ collider as a $\pzero$ factory will typically allow precision measurements of enough observables to determine the number of technicolors of the theory and (up to a discrete set of ambiguities) the fundamental parameters of the low-energy effective Lagrangian describing the $\pzero$'s Yukawa couplings.