Coherent Exclusive Exponentiation for Precision Monte Carlo Calculations

Abstract

In this contribution we give a short overview of the new Coherent Exclusive Exponentiation (CEEX) which is implemented in the new \KK MC event generator for the process $e^+e^-\to f\bar{f} +nγ$, $f=μ,τ,d,u,s,c,b$ with validity for center of mass energies from $τ$ lepton threshold to 1TeV, that is for LEP1, LEP2, SLC, future Linear Colliders, $b,c,τ$-factories etc. In CEEX effects due to photon emission from initial beams and outgoing fermions are calculated in QED up to second-order, including all interference effects. Electroweak corrections are included in first-order, at the amplitude level. Beams can be polarized longitudinally and transversely, and all spin correlations are incorporated in an exact manner. We describe briefly the essence of CEEX as compared with older exclusive variants of the exponentiation (EEX) and present samples of the numerical results, concentrating on the question of the technical and physical precision for the total cross section and for the charge asymmetry. New results on the interference between initial and final state photon emission at LEP2 energies are also shown.