Polarization and spin effects in neutralino production and decay

Abstract

We study the production of neutralinos \(e^+ e^- \to\tilde{\chi}^{0}_i\tilde{\chi}^{0}_j\) with polarized beams and the subsequent decays \(\tilde{\chi}^{0}_{i} \to \tilde{\chi}^0_k\ell^{+}\ell^{-}\) and \(\tilde{\chi}^{0}_{j} \to \tilde{\chi}^0_l \ell^{+}\ell^{-}\), including the complete spin correlations between production and decay. We present analytical formulae for the differential cross section of the combined process of production and decay of neutralinos. We also allow for complex couplings. The spin correlations have a strong influence on the decay angular distributions and the corresponding forward–backward asymmetries. They are very sensitive to the SUSY parameters and depend strongly on the beam polarizations. We present numerical results for the cross section and the electron forward–backward asymmetry for \(e^+ e^- \to\tilde{\chi}^{0}_1\tilde{\chi}^{0}_2\), \(\tilde{\chi}^{0}_{2} \to \tilde{\chi}^0_1 e^{+} e^{-}\). We study the dependence on the parameter \(M'\) for various mass splittings between \(\tilde{e}_L\) and \(\tilde{e}_R\) and different beam polarizations.