PHOTOS Monte Carlo – its phase-space and benchmarks

by Was, Z. (IFJ-PAN Cracow)

Friday 23 Feb 2007, 14:00 → 15:00 Europe/Zurich

TH Auditorium (CERN)

Recently, PHOTOS Monte Carlo became widely used in HEP experiments, for simulation of QED bremsstrahlung in decays of particles and resonances. It is thus of interest to review its performance. For that purpose its phase-space parametrization will be reviewed and it will be shown that it covers full phase-space for arbitrary number of photons and in any decay. For final states of only one charged particle the phase space parametrization is exact. In other cases, requiring more complex presampler for collinear singularities, well localized and easy to revert approximations are introduced in phase space Jacobians. Thanks to clear separation into phase-space and matrix element, it is possible to introduce process dependent form-factors. Possible extension of the solution beyond QED bremsstrahlung in decays will be also discussed.