Chargino and neutralino production at $$e^+e^-$$ e + e - colliders in the complex MSSM: a full one-loop analysis

Abstract

Abstract For the search for charginos and neutralinos in the Minimal Supersymmetric Standard Model (MSSM) as well as for future precision analyses of these particles an accurate knowledge of their production and decay properties is mandatory. We evaluate the cross sections for the chargino and neutralino production at $$e^+e^-$$ e + e - colliders in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of the production mechanisms $$e^+e^- \rightarrow {\tilde{\chi }}_{c}^\pm {\tilde{\chi }}_{c^\prime }^\mp $$ e + e - → χ ~ c ± χ ~ c ′ ∓ and $$e^+e^- \rightarrow {\tilde{\chi }}_{n}^0 {\tilde{\chi }}_{n^\prime }^0$$ e + e - → χ ~ n 0 χ ~ n ′ 0 including soft and hard photon radiation. We mostly restricted ourselves to a version of our renormalization scheme which is valid for $$|M_1| < |M_2|, |\mu |$$ | M 1 | < | M 2 | , | μ | and $$M_2 \ne \mu $$ M 2 ≠ μ to simplify the analysis, even though we are able to switch to other parameter regions and correspondingly different renormalization schemes. The dependence of the chargino/neutralino cross sections on the relevant cMSSM parameters is analyzed numerically. We find sizable contributions to many production cross sections. They amount to roughly $${\pm }15\%$$ ± 15 % of the tree-level results but can go up to $${\pm }40\%$$ ± 40 % or higher in extreme cases. Also the complex phase dependence of the one-loop corrections was found non-negligible. The full one-loop contributions are thus crucial for physics analyses at a future linear $$e^+e^-$$ e + e - collider such as the ILC or CLIC.