Precision simulations with TAUOLA and PHOTOS

Abstract

The status of the Monte Carlo programs for the simulation of τ -lepton production and decay in high-energy accelerator experiments is reviewed. No significant changes in the organization of the programs were introduced since previous TAU conference, that is why we will concentrate on some physical topics: (i) For TAUOLA Monte Carlo generator of τ -lepton decays, simulation of five scalar final states based on the hadronic current became available for the first time. As an example, simple, but realistic current for final states: 2 π − π + 2 π 0 ν τ , π − 4 π 0 ν τ and 3 π − 2 π + ν τ is presented. The current is installed into TAUOLA . (ii) For the PHOTOS Monte Carlo, which generates radiative corrections in arbitrary decays, new results on next to leading order corrections became available for some decay modes. The complete corrections were installed for leptonic Z and B decays into a pair of scalars. (iii) During conference discussions, the importance of checking the uncertainty of the overall normalization for KORALB and KKMC simulations was underlined. Necessary steps to check the uncertainty and to adjust the programs to Belle and BaBar conditions are also listed.