Model independent QED corrections to the process ep →\to eX

We give an exhaustive presentation of the semi-analytical approach to the model independent leptonic QED corrections to deep inelastic neutral current lepton-nucleon scattering. These corrections include photonic bremsstrahlung from and vertex corrections to the lepton current of the order {\cal O}(\alpha) with soft photon exponentiation. % A common treatment of these radiative corrections in several variables -- leptonic, hadronic, mixed, Jaquet-Blondel variables -- has been developed and double differential cross-sections are calculated. In all sets of variables we use some structure functions, which depend on the hadronic variables and which do not have to be defined in the quark parton model. The remaining numerical integrations are twofold (for leptonic variables) or onefold (for all other variables). For the case of hadronic variables, all phase space integrals have been performed analytically. Numerical results are presented for a large kinematical range, covering fixed target as well as collider experiments at HERA or LEP\otimesLHC, with a special emphasis on HERA physics.We give an exhaustive presentation of the semi-analytical approach to the model independent leptonic QED corrections to deep inelastic neutral current lepton-nucleon scattering. These corrections include photonic bremsstrahlung from and vertex corrections to the lepton current of the order ${\cal O}(\alpha)$ with soft photon exponentiation. % A common treatment of these radiative corrections in several variables -- leptonic, hadronic, mixed, Jaquet-Blondel variables -- has been developed and double differential cross-sections are calculated. In all sets of variables we use some structure functions, which depend on the hadronic variables and which do not have to be defined in the quark parton model. The remaining numerical integrations are twofold (for leptonic variables) or onefold (for all other variables). For the case of hadronic variables, all phase space integrals have been performed analytically. Numerical results are presented for a large kinematical range, covering fixed target as well as collider experiments at HERA or LEP$\otimes$LHC, with a special emphasis on HERA physics

An analytical program for fermion pair production in e+e- annihilation

We describe how to use {\tt ZFITTER}, a program based on a semi-analytical approach to fermion pair production in e^+ e^- annihilation and Bhabha scattering. A flexible treatment of complete {\cal O}(\alpha) QED corrections, also including higher orders, allows for three calculational {\bf chains} with different realistic sets of restrictions in the photon phase space. {\tt ZFITTER} consists of several {\bf branches} with varying assumptions on the underlying hard scattering process. One includes complete {\cal O}(\alpha) weak loop corrections with a resummation of leading higher-order terms. Alternatively, an ansatz inspired from S-matrix theory, or several model-independent effective Born cross sections may be convoluted. The program calculates cross sections, forward-backward asymmetries, and for \tau~pair production also the final-state polarization. Various {\bf interfaces} allow fits to be performed with different sets of free parameters

Standard model processes

We present the results obtained by the Standard Model Process group in the CERN Workshop "Physics at LEP2" (1994/95)

Off-shell WW pair production in e+e−e^+ e^- annihilation: the CC11 process

The various four-fermion production channels in e + e − annihilation are discussed and the CC11 process $e^+e^- \to \bar f_{1}^{u}f_{1}^{d}f_{2}^d\bar f_{2}^{d}≠ e$ , is studied in section $d^2\sigma/ds_1 ds_2$ , with $s_1 , s_2$ being the invariant masses squared of the two fermion pairs, may be expressed by six generic functions. All but one may be found in the literature. The cross section, including initial-state radiation and the Coulomb correction, is discussed and compared with other calculations from low energies up to √ s = 2 TeV