Determining SUSY parameters in chargino pair-production in e⁺ e^- collisions

In most supersymmetric theories, charginos X̃_1,2^±, mixtures of charged color-neutral gauginos and higgsinos, belong to the class of the lightest supersymmetric particles. They are easy to observe at e⁺ e^- colliders. By measuring the total cross sections and the left-right asymmetries with polarized electron beams in e⁺ e^- → X̃_i- X̃_j⁺ [i, j = 1, 2], the chargino masses and the gaugino-higgsino mixing angles can be determined. From these observables the fundamental SUSY parameters can be derived: the SU(2) gaugino mass M₂, the modulus \μ\ and cosΦ_μ of the higgsino mass parameter, and tan β = υ₂/υ₁, the ratio of the vacuum expectation values of the two neutral Higgs doublet fields. The solutions are unique; the CP-violating phase Φ_μ can be determined uniquely by analyzing effects due to the normal polarization of the charginos.