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Determining SUSY Parameters in Chargino Pair-Production in $e^+e^-$ Collisions

In most supersymmetric theories, charginos $\tildeχ^\pm_{1,2}$, 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 $e^+e^-\to\tildeχ_i^-\tildeχ_j^+ [i,j=1,2]$, 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 $M_2$, the modulus $|μ|$ and $\cos Φ_μ$ of the higgsino mass parameter, and $\tanβ= v_2/v_1$, 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.