The FMNRxPYTHIA interface for Heavy Quark production at HERA

A method to calculate heavy flavor visible-level cross sections at Next-to-Leading Order (NLO) in Quantum Chromodynamics (QCD), based on an interface of the FMNR program to PYTHIA, is described. It uses the NLO prediction at quark level provided by FMNR, with a statistical reduction procedure (REDSTAT) that allows a link to PYTHIA 6.2 to be made, from where the description of the full hadron fragmentation and decay chain is obtained. The method is applied to ep -> b bbar X -> D* mu X and mu+ mu- X final states at HERA. Comparisons of the data and NLO cross sections at visible and b-quark level were found to be consistent.