. We discuss the pair production of charginos in collisions of polarized photons, γγ→χ̃_i^+ χ̃_i^- (i = 1,2) , and the subsequent leptonic decay of the lighter chargino χ̃_1^+ →χ̃_1^0 e^+ ν_e including the complete spin correlations. Analytical formulae are given for the polarization and the spin-spin correlations of the charginos. Since the production is a pure QED process the decay dynamics can be studied separately. For high energy photons from Compton backscattering of polarized laser pulses off polarized electron beams numerical results are presented for the cross section, the angular distribution and the forward-backward asymmetry of the decay positron. Finally we study the dependence on the gaugino mass parameter M 1 and on the sneutrino mass for a gaugino-like MSSM scenario.

At future e+- e- linear colliders, the event rates and clean signals of scalar fermion production - in particular for the scalar leptons - allow very precise measurements of their masses and couplings and the determination of their quantum numbers. Various methods are proposed for extracting these parameters from the data at the sfermion thresholds and in the continuum. At the same time, NLO radiative corrections and non-zero width effects have been calculated in order to match the experimental accuracy. The substantial mixing expected for the third generation sfermions opens up additional opportunities. Techniques are presented for determining potential CP-violating phases and for extracting tan(beta) from the stau sector, in particular at high values. The consequences of possible large mass differences in the stop and sbottom system are explored in dedicated analyses.

We update theoretical studies of the physics opportunities presented by {mu}{sup +} {mu}{sup -} Higgs factories. Interesting measurements of the Standard Model Higgs decays into {bar b}b, {tau}{sup +} {tau}{sup -} and WW* may be possible if the Higgs mass is less than about 160 GeV, as preferred by the precision electroweak data, the mass range being extended by varying appropriately the beam energy resolution. A suitable value of the beam energy resolution would also enable the uncertainty in the b-quark mass to be minimized, facilitating measurements of parameters in the MSSM at such a first {mu}{sup +} {mu}{sup -} Higgs factory. These measurements would be sensitive to radiative corrections to the Higgs-fermion-antifermion decay vertices, which may violate CP. Radiative corrections in the MSSM may also induce CP violation in Higgs-mass mixing, which can be probed via various asymmetries measurable using polarized {mu}{sup +} {mu}{sup -} beams. In addition, Higgs-chargino couplings may be probed at a second {mu}{sup +} {mu}{sup -} Higgs factory.

We investigate pair production of selectrons in e − e − scattering with subsequent decay into an electron and the LSP including ISR and beamstrahlung. This process can be used at a linear collider to measure the selectron masses and the gaugino mass parameter M 1 very precisely.

We investigate selectron pair production and decay in e - e - scattering and e + e - annihilation with polarized beams taking into account neutralino mixing as well as initial state radiation and beamstrahlung corrections. One of the main advantages of having both modes at disposal is their complementarity concerning the threshold behavior of selectron pair production. In e - e - the cross sections at threshold for \(\tilde{e}_{\mathrm {R}} \tilde{e}_{\mathrm {R}}\) and \(\tilde{e}_{\mathrm {L}} \tilde{e}_{\mathrm {L}}\) increase proportional to the momentum of the selectron and in e + e - that for \(\tilde{e}_{\mathrm {R}} \tilde{e}_{\mathrm {L}}\). Measurements at threshold with polarized beams can be used to determine the selectron masses \(m_{\tilde{e}_{\mathrm {{L/R}}}}\) precisely. Moreover we discuss how polarized electron and positron beams can be used to establish directly the weak quantum numbers of the selectrons. We also use selectron pair production to determine the gaugino mass parameter M1. This is of particular interest for scenarios with non-universal gaugino masses at a high scale resulting in \(\vert M_1\vert \gg \vert M_2\vert\) at the electroweak scale. Moreover, we consider also the case of non-vanishing selectron mixing and demonstrate that it leads to a significant change in the phenomenology of selectrons.

We update theoretical studies of the physics opportunities presented by µ + µ − Higgs factories. Interesting measurements of the Standard Model Higgs decays into ¯ bb, τ + τ − and W W * may be possible if the Higgs mass is less than about 160 GeV, as preferred by the precision electroweak data, the mass range being extended by varying appropriately the beam energy resolution. A suitable value of the beam energy resolution would also enable the uncertainty in the b-quark mass to be minimized, facilitating measurements of parameters in the MSSM at such a first µ + µ − Higgs factory. These measurements would be sensitive to radiative corrections to the Higgs-fermion-antifermion decay ver-tices, which may violate CP. Radiative corrections in the MSSM may also induce CP violation in Higgs-mass mixing, which can be probed via various asymmetries measurable using polarized µ + µ − beams. In addition, Higgs-chargino couplings may be probed at a second µ + µ − Higgs factory.

TESLA Technical Design Report, Part VI, Chapter 1: The Photon Collider at TESLA

The TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider

We study the different linear collider modes with regard to the determination of the gaugino mass parameter M-1. In a specific mSUGRA inspired scenario We compare four processes with polarized beams: (a) e(+)e(-) --> (chi) over tilde (0)(1)(chi) over bar (0)(2) --> (chi) over tilde (0)(1)(chi) over tilde (0)(1)e(+)e(-), (b) e(-)gamma --> (chi) over tilde (0)(1)(e) over tilde (L/R) --> (chi) over tilde (0)(1)e(-), (c) gammagamma --> (chi) over tilde (0)(1)(chi) over tilde (0)(1)e(+)e(-)v(e)(v) over tilde (e), (d) e(-)e(-) --> (e) over bar (-)(L/R)(e) over tilde (-)(L/R) --> (chi) over tilde (0)(1)(chi) over tilde (0)(1)e(-)e(-).

High energy photon colliders (γγ,γe) are based on e-e- linear colliders where high energy photons are produced using Compton scattering of laser light on high energy electrons just before the interaction point. This paper is a part of the Technical Design Report of the linear collider TESLA.1 Physics program, possible parameters and some technical aspects of the photon collider at TESLA are discussed.

This Resource Book reviews the physics opportunities of a next-generation e+e− linear collider and discusses options for the experimental program. Part 1 contains the table of contents and introduction and gives a summary of the case for a 500 GeV linear collider. ∗Work supported in part by the US Department of Energy under contracts DE–AC02– 76CH03000, DE–AC02–98CH10886, DE–AC03–76SF00098, DE–AC03–76SF00515, and W–7405– ENG–048, and by the National Science Foundation under contract PHY-9809799.

We study the associated production of selectrons and neutralinos with subsequent leptonic decay of the selectron in eγ scattering within the framework of Minimal Supersymmetric Standard Model and Next-to-Minimal Supersymmetric Standard Model. Due to the weak couplings of singlino dominated neutralinos, associated neutralino production e+e−→χ̃10χ̃20 at a linear collider can be strongly suppressed in some regions of the parameter space. Then the process eγ→ẽL/Rχ̃1/20→eχ̃1/20χ̃10 can give additional information on the underlying theory and the character of χ̃10 and χ̃20.

We investigate associated production of selectrons and the lightest neutralino (LSP) in the process e^- + gamma –> neutralino_1 + selectron_L/R with the selectron subsequently decaying into an electron and the LSP. Total cross sections and various polarization asymmetries are calculated for photons produced by Compton backscattering of a polarized laser beam at an e^+e^- linear collider with CMS energy √(s_ee)=500 GeV and with polarized beams. The total cross section and in particular the polarization asymmetries show a characteristic dependence on the gaugino mass parameter M_1. Therefore this process is suitable for testing the GUT relation M_1=M_2·5/3tan^2θ_W.

With the process e^-γ→χ̃_1^0 ẽ_L/R^- → e^- χ̃_1^0 χ̃_1^0 it is possible to constrain selectron masses above the kinematical limit of the pair production process in e^+e^- colliders. We investigate these mass ranges and discuss the possibility to test the renormalization group equations for the selectron masses.

With the process e(-)gamma --> <(chi)over tilde>(0)(1)(e) over tilde(L/R)(-) --> e(-)<(chi)over tilde>(0)(1)<(chi)over tilde>(0)(1) it is possible to constrain selectron masses above the kinematical limit of the pair production process in e(+)e(-) colliders. We investigate these mass ranges and discuss the possibility to test the renormalization group equations for the selectron masses.

With the process $e^-\gamma \to \tilde{\chi}_1^0 \tilde{e}_{L/R}^- \to e^- \tilde{\chi}_1^0 \tilde{\chi}_1^0$ it is possible to constrain selectron masses above the kinematical limit of the pair production process in $e^+e^-$ colliders. We investigate these mass ranges and discuss the possibility to test the renormalization group equations for the selectron masses.

In the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation, angular distributions and total cross sections for the process e(-)gamma --> <(chi)over tilde>(0)(1) (e) over tilde(L/R) --> <(chi)over tilde>(0)(1)<(chi)over tilde>(0)(1)e(-) are presented in the e(-)gamma-cms and the e(-)e(+)-cms of a photos linear collider (PLC) with CMS-energy root s = 500 GeV.