PHOTOS Monte Carlo: a precision tool for QED correctionsin Z and W decays

We present a discussion of the precision for the PHOTOS Monte Carlo algorithm, with improved implementation of QED interference and multiple-photon radiation. The main application of PHOTOS is the generation of QED radiative corrections in decays of any resonances, simulated by a "host" Monte Carlo generator. By careful comparisons automated with the help of the MC-TESTER tool specially tailored for that purpose, we found that the precision of the current version of PHOTOS is of 0.1% in the case of Z and W decays. In the general case, the precision of PHOTOS was also improved, but this will not be quantified here. Received: 7 June 2005, Revised: 5 August 2005, Published online: 21 October 2005 Z. Was: Supported in part by the EU grant MTKD-CT-2004-510126, in partnership with the CERN Physics department, and Polish State Committee for Scientific Research (KBN) grant 2 P03B 091 27 for the years 2004-2006