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

For an attractive class of dynamical symmetry breaking (technicolor) models, the lightest neutral pseudo-Nambu-Goldstone boson (P 0) contains only downtype techniquarks and charged technileptons. We discuss the prospects for discovering and studying the P 0 of such models at the Tevatron and the LHC and at future e+e− and μ+μ− colliders. Depending upon the number of technicolors, NTC , discovery of the P 0 at the Tevatron and the LHC in the gg → P 0 → γγ mode could be possible over a wide range of mass. For NTC = 4, we estimate that RunII Tevatron data can be used to exclude or discover a P 0 in the 50−200 GeV mass range, and at the LHC, a very precise measurement of Γ(P 0 → gg)B(P 0 → γγ) will be possible. For NTC = 4, discovery of the P 0 at an e+e− collider via the reaction e+e− → γP 0 should be possible for an integrated luminosity of L = 100 fb−1 at √ s = 500 GeV as long as mP 0 is not near mZ . However, measuring the branching fractions and couplings of the P 0 with precision would require much more luminosity. In the γγ collider mode of operation at an e+e− collider, the γγ → P 0 → bb signal should be very robust and could be measured with high statistical accuracy for a broad range of mP 0 if NTC = 4. For the minimal NTC = 1 case, detection of the P 0 at the Tevatron and in e+e− collisions will be very difficult, and the precision of measurements at the LHC and the γγ collider decline markedly. Only a μ+μ− collider yields a P 0 production rate that does not depend markedly upon NTC . At a μ +μ− collider, depending upon On leave from Dipartimento di Fisica Università di Firenze, I-50125 Firenze, Italia