A Nondiagonal Pair of Majorana Particles at $e^{+}{e}^{-}$ Colliders

We perform a comprehensive and model-independent analysis for characterizing the spin and dynamical structure of the production of a non-diagonal pair of Majorana particles with different masses and arbitrary spins, $e^-e^+\to X_2 X_1$,followedbyasequentialtwo-bodydecay,$X_2\to Z X_1$, of the heavier particle $X_2$ into a $Z$ gauge boson and the lighter particle $X_1$ escaping undetected at high-energy $e^{+}{e}^{-}$ colliders. Standard leptonic $Z$-boson decays, $Z\to {\mathrm{\ell }}^{-}{\mathrm{\ell }}^{+}$ with $\mathrm{\ell }=e$ or $\mu$, are employed for precisely diagnosing the $Z$ polarization influenced by the production and decay processes. Based on helicity formalism and Wick helicity rotation for describing the correlated production-decay amplitudes and distributions, we work out the implications on the amplitudes and distributions of discrete CP symmetry and the Majorana condition that two particles are their own anti-particles. For the sake of a concrete illustration, an example of this type in the minimal supersymmetric Standard Model is investigated in detail.