We describe the physics potential of e + e − linear colliders in this report. These machines are planned to operate in the first phase at a center-of-mass energy of 500 GeV, before being scaled up to about 1 TeV. In the second phase of the operation, a final energy of about 2 TeV is expected. The machines will allow us to perform precision tests of the heavy particles in the Standard Model, the top quark and the electroweak bosons. They are ideal facilities for exploring the properties of Higgs particles, in particular in the intermediate mass range. New vector bosons and novel matter particles in extended gauge theories can be searched for and studied thoroughly. The machines provide unique opportunities for the discovery of particles in supersymmetric extensions of the Standard Model, the spectrum of Higgs particles, the supersymmetric partners of the electroweak gauge and Higgs bosons, and of the matter particles. High precision analyses of their properties and interactions will allow for extrapolations to energy scales close to the Planck scale where gravity becomes significant. In alternative scenarios, like compositeness models, novel matter particles and interactions can be discovered and investigated in the energy range above the existing colliders up to the TeV scale. Whatever scenario is realized in Nature, the discovery potential of e + e − linear colliders and the high-precision with which the properties of particles and their interactions can be analysed, define an exciting physics programme complementary to hadron machines.
We describe version 2.0 of the Fortran program GENTLE/4fan for the semi-analytic computation of cross-sections and distributions in four-fermion production in e + e − annihilation. GENTLE/4fan covers all charged current and neutral current fourfermion final states with no identical particles, no electrons, and no electron neutrinos in the final state. Initial state radiation representing the most relevant quantum corrections and anomalous triple gauge boson couplings have been included. Semi-analytic; numerical integration of analytic formulae: (i) Born approximation: Numerical integrations over two virtualities s 1 , s 2 plus optionally over the boson production angle θ; (ii) QED corrections in the flux function approach (FF): one additional numerical integration over virtuality s ′ ; (iii) QED corrections in the structure function approach (SF): alternatively to (ii), two additional numerical integrations over x 1 , x 2 Restrictions on complexity of the problem: Only selective experimental cuts are possible; the program calculates total cross-sections and the distribution in the boson production angle; background contributions are available only for selected final state configurations; no inclusion of pure weak corrections Typical running time:The running time strongly depends upon the options used; one finds e.g.: Born cross-section on-shell: below one sec., off-shell: few secs.; LLA QED corrections (FF) on-shell: few secs.; off-shell: few mins.; LLA QED corrections (SF) on-shell: few secs.; off-shell: several mins.; complete ISR (FF): on-shell: few mins., off-shell: several hours; with background: from few secs. (no QED) to several hours (with QED); with anomalous couplings: from few secs. (no QED) to several mins. (with QED)
We present the Monte Carlo event generator WOPPER for pair production of W 's and their decays at high energy e + e − colliders. WOPPER includes the effects from finite W width and focusses on the calculation of higher order electromagnetic corrections in the leading log approximation including soft photon exponentiation and explicit generation of exclusive hard photons.
We calculate distributions for τ + τ − γ production at LEP 1 taking into account a potentially existing anomalous magnetic moment a τ of the τ lepton. The existing upper limits for |a τ | are known from the dependence of the decay Z 0 → τ + τ − γ on a 2 τ and are of the order of (1 − 5)%. We show that such limits are also sensitive to linear terms in a τ , which are of equal importance at |a τ | ∼ (1 − 2)% and dominate below this value. Contributions from an electric dipole moment d τ do not interfere with the electromagnetic vertex or with the anomalous magnetic moment. Appropriate formulae are derived.
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