Search

11 pp. (1995)., The measurement of the forward-backward asymmetries of heavy quarks provides one of the most precise determinations of $\sin~2\theta_W$ in $Z$ decays. We discuss in detail the one--loop QCD radiative corrections to these asymmetries. Results are given for single heavy--quark jet asymmetries and asymmetries of the thrust axis, as well as for heavy--quark two--jet final states.}

24 pp. (1995)., SMATASY is an interface for the ZFITTER package and may be used for the model independent description of the Z resonance at LEP 1 and SLC. It allows the determination of the Z mass and width and its resonance shape parameters r and j for cross-sections and their asymmetries. The r describes the peak height and j the interference of the Z resonance with photon exchange in each scattering channel and for $\sigma_T$, $\sigma_{FB}$, $\sigma_{lr}$, $\sigma_{pol}$ etc. separately. Alternatively, the helicity amplitudes for a given scattering channel may be determined. We compare our formalism with other model independent approaches. The model independent treatment of QED corrections in SMATASY is applicable also far away from the Z peak.

10 pp. (1995)., Leptons, quarks and gauge bosons are assumed to be pointlike particles in the Standard Model. Stringent bounds on the radii of quarks and leptons and their weak anomalous magnetic moments can be derived from the high-precision measurements at LEP and SLC. We find a model-independent bound ofR≲10−17 cm for quark and lepton radii. HERA will provide complementary information on the electromagnetic static properties of the quarks and the parameters of the charged quark currents.

25 pp. (1992)., Using the processeψ→Wv we study theWWψ vertex ine+e− collisions with polarized beams at a future 500 GeV collider. The equivalent photon approximation and its accuracy are discussed for the case of polarized electron beams. The resulting photon spectrum is then used to compute the total cross section as well as verious differential distributions for the processe+e−→e+W−v. Special emphasis is put on the effects of using polarized electron beams and their influence on the sensitivity to anomalous couplings.

27 pp. (1983).

31 pp. (1982).

(1980). doi:10.1103/PhysRevLett.45.867, The forward-backward asymmetry of the normal to the event plane for e+e− annihilation into three jets in higher-order perturbation-theory (>~αs2) quantum chromodynamics is calculated. This could serve to establish the non-Abelian gluon self-couplings.

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Bottom quarks 18 pp. (1984)., Recent results on weak interactions from experiments at the PETRA e+e− storage ring are presented. They include the determination of the weak neutral couplings in the purely leptonic reactions e+e−→e+e−, e+e−→μ+μ− and e+e− →τ+τ− and in the production of heavy charm and bottom quarks e+e−→cc̄ and e+e−→bb̄. The weak charged current is tested in τ decays, where new data on semihadronic branching ratis and a new lifetime measurement is reported, and in semileptonic decays of charm and bottom quarks.

36 pp. (1984).

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76 pp. (1988).

20 pp. (1981).

54 pp. (1982).