6.1 Introduction

Total cross sections of standard model processes below 1 TeV are shown in Fig. 6.1. As seen in the figure, productions of multiple gauge bosons are characteristic feature of experiments at JLC. Precise measurements of their properties, such as masses and couplings, allow us to test models at higher order and serve as tools to probe physics at high energy scale. A clean environment, polarized beams, variable collision energies and high luminosities at JLC are essential ingredients for precise measurements. When operated at the Z pole and just above the W pair threshold, Giga Z and Mega W samples can be accumulated. These statistics are two orders of magnitude more than LEP-I/II. At 500 GeV and above, gauge cancellation among diagrams of the $e^+ e^- \rightarrow W^+ W^-$ process becomes severer, which allows us a direct measurement of triple-gauge-boson couplings at a precession required to probe loop effects. At higher energies, processes which involve t-channel diagrams increase cross sections with energy, from which WW scattering processes could be measured. In general, models without elementary Higgs bosons predict strong interaction among longitudinal polarized W bosons. Such effects would be observed through the final-state interaction of W's in the $e^+ e^- \rightarrow W^+ W^-$process or resonance production in processes such as $e^+e^-\rightarrow \nu\bar{\nu}W^+W^-$.

In the following subsections, we discuss topics on measurements of the W boson mass and triple-gauge-boson couplings.

  

Figure 6.1: Cross sections of the standard model processes at energies below 1 TeV.

Eps file of this figure