High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A repository for computer programs is provided which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e + e − linear collider experiments, i.e., masses, mixings, decay widths and production cross sections for supersymmetric particles. In addition, programs for calculating high-precision low energy observables, the density of cold dark matter (CDM) in the universe as well as the cross sections for CDM search experiments are included. The SPA scheme still requires extended efforts on both the theoretical and experimental side before data can be evaluated in the future at the level of the desired precision. We take here an initial step of testing the SPA scheme by applying the techniques involved to a specific supersymmetry reference point.
We present a high precision calculation of chargino and neutralino pair production at e + e − colliders. Within the Minimal Supersymmetric Standard Model, the full one-loop and higher order QED corrections are included. Special care has been taken in the definition of the Lagrangian input parameters. Furthermore, the proper inclusion of QED corrections and the separation of weak and QED corrections are discussed. We show numerical results for total cross sections, as well as forward-backward and left-right asymmetries for the SPS1a' scenario as proposed in the SPA project. The complete corrections are about 10% and in some cases even larger, in particular forχ 0 iχ 0 j production with sizeable higgsino components. These corrections have to be taken into account in a high precision analysis.
In the Minimal Supersymmetric Standard Model (MSSM) the masses of the neutralinos and charginos depend on the gaugino and higgsino mass parameters M , M and µ. If supersymmetry is realized, the extraction of these parameters from future high energy experiments will be crucial to test the underlying theory. We present a consistent method how on-shell parameters can be properly defined at one-loop level and how they can be determined from precision measurements. In addition, we show how a GUT relation for the parameters M and M can be tested at one-loop level. The numerical analysis is based on a complete one-loop calculation. The derived analytic formulae are given in the appendix.
We present the full one-loop radiative corrections to pair production of neutralinos in e + e − collisions within the Minimal Supersymmetric Standard Model. Particular attention is paid to the definition of weak and QED corrections. The non-universal QED corrections are extracted by subtracting the initial state radiation. We give numerical results for two different SUSY scenarios for e + e − →χ 0 1χ 0 2 and e + e − →χ 0 2χ 0 2 . The weak and QED corrections are up to several percent or even higher and need to be taken into account at future linear collider experiments.
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