ok great, then this can go in, along with D94, I'll take care of landing them both tomorrow

Great, many thanks!

Thanks for adding the comment @lmassa. However, it looks like some other things have changed as well. See:
https://phab.hepforge.org/D94?vs=402&id=412#toc
Are those additional changes intentional?

Many thanks for this @abudinen. After the reviews by @jback and me on the CERN gitlab MR evtgen/evtgen!4, I think this is ready to go, unless @jback has any further comments, or @kreps would like to comment?

In D94#2535, @abudinen wrote:

It might be a good idea to add a comment in the code that the amplitude magnitudes are obtained from the mentioned BaBar paper but corrected for normalisation.

The plots look good, e.g. the m_ij^2 projections as per your slide 19:

Many thanks for this @lmassa and apologies for the delay in looking at it.

Comparisons look good I think.
You can find the plots here:
/home/epp/phsdba/Development/EvtGen/pythia8-build-problem/install/share/EvtGen/validation/gifFiles
if you want to take a quick look.

In D96#2504, @jback wrote:

Thanks for updating the interface, Tom. I agree that it will be easier to release this as a patch release based on R02-02-00.

We don't have any Pythia-specific JSON tests at the moment, although the scripts genAllDecayExamples.sh and compareAllDecays.sh can be used to generate and compare momentum and multiplicity histograms for a range of Pythia modes, although I don't think we currently have reference Pythia ROOT files for the comparison script.

We should also decide how to release this once reviewed and approved. Obviously this can be merged into master but do we then release 02-03-00 from master (i.e. also rolling-up all other changes that have accumulated there) or do we cherry-pick this commit to a branch based on 02-02-00 and release 02-02-01 from that? I'm not sure that we want to release everything that's in master right now, i.e. before we finish fixing all the models that show problems in the tests. So I would tend towards releasing in a patch release.

Please also add an entry in the release notes, which should reference either this Differential revision or the corresponding Maniphest task

Just a few trivial tidy-ups

Many thanks Mark, this looks great. Just a few small suggestions here and there.

Thanks, please go ahead and land this

Looks good, thanks @abudinen.

Can you please change the visibility and edit policies according to the instructions?