CP-sensitive observables in $e^ + e^-\to\tilde\chi^0_i \tilde\chi^0_j$ and neutralino decay into the Z boson

Abstract

We study CP-sensitive observables in the neutralino production $e^ + e^-\to\tilde\chi^0_i \tilde\chi^0_j$ and the subsequent two-body decays of the neutralino $\tilde\chi^0_i \to \chi^0_n Z$ and of the Z boson $Z \to \ell \bar\ell (q\bar q)$ . We identify the CP-odd elements of the Z boson density matrix and propose CP-sensitive triple-product asymmetries. We calculate these observables and the cross sections in the minimal supersymmetric standard model with complex parameters μ and M 1 for an e + e - linear collider with $\sqrt{s} = 800$ GeV and longitudinally polarized beams. We show that the asymmetries can reach $3\%$ for $Z \to \ell \bar\ell $ and $18\%$ for $Z \to q\bar q$ and discuss the feasibility of measuring these asymmetries.