Comment 4 for bug 1015032

Dear Johannes,

Thanks a lot for this bug report. It turned out that the problem was related to how matrix elements were combined, so it happened (sometimes, in very complicated processes like this) that two matrix element that had the same diagrams but different relative particle ordering could be combined into a single matrix element. This lead to an error in the particle code assignment at event generation time, giving the Z > e+ mu- events.

I have fixed this in the development version 1.4.7. Can you please branch this version and make sure that the problem doesn't occur there? You simply install bazaar from http://wiki.bazaar.canonical.com/Download and then download the branch using

bzr branch lp:~maddevelopers/madgraph5/1.4.7

Many thanks,
Johan