Dresden 2000 – wissenschaftliches Programm

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T: Teilchenphysik

T 508: Höhere Ordnungen

T 508.3: Vortrag

Donnerstag, 23. März 2000, 10:45–11:00, H\,204

Bhabha scattering with ZFITTER — •Silviya Arkadova and Tord Riemann — DESY Zeuthen, Platanenallee 6, 15738 Zeuthen

Fermion pair production in e+e− annihilation still plays an important role for high precision measurements to the Standard Model (SM) or for searches beyond it at e+e− colliders like LEP and SLC. In the leptonic case, e+e−→ l+l−, Bhabha scattering is particularly interesting, e.g. for luminosity measurements or because of its large cross sections, e.g. at √s=189 GeV: σtot(e+e−)= 304.6 pb; |cosθ| < 0.96; θacol<10∘; σtot(µ+µ−)= 7.8 pb. The aim of this project is to calculate radiative corrections to Bhabha scattering. This is treated in the semi-analytical Fortran program ZFITTER, describing observables with realistic experimental cuts as convolution integrals of effective Born observables. We are focussing on special kinematical cuts on the final state minimal energies and acollinearity angle. The calculation implies three- (two-) dimensional analytical integrations together with a numerical convolution over s′≡ ml+l−2. In the case of Bhabha scattering, extra t-channel corrections have to be dealt with, leading to a more complex structure of the propagators and integrals than for the simpler leptonic case, l≠ e.