Adding tWH Parton History

Merged Mohamed Aly requested to merge maly/athena:maly-dev into 21.2

This MR adds another cateogry to the possible parton shower histories, directed at the tWH process. The new files are under xAOD/TopPhys/TopPartons/ with the name CalcTwhPartonHistory. The new scripts are a re-purposing of the tHq parton history code, where the information on the W from the associated production is added. The information about the W boson is computed from CalcTopPartonHistory::Wt_W. The implementation saves information on top, W from Top (including first decay), b from Top, W not from Top (including first decay) and Higgs boson (including first and secondary decays). I also require a secondary b in the event (from 4FS, or gluon-splitting).

I subsequently added the new category of TopPartonHistory the AnalysisTop configuration template code and the top-xaod executable code.

I also noticed in CalcTopPartonHistory::topAfterFSR_SC that there is an order-dependant logic when determining the hadronisation, so I fixed that to remove the order dependance. The existing code was not checking that v_status11_top.size() == 0 before deciding that an event is Pythia8. This meant that if v_status11_top.size() == 1, the top is taken to be the pythia8 one, whereas it should be Herwig. This was ok because the next statement overwritten this assignment if v_status11_top.size() == 1 to use the correct top.

I have produced some basic validation plots (attached as zip) with 10,000 MC events (~165 weighted events). The validation plots were produced with AnalysisTop release 21.2.321. The AT configuration used is also attached. The file I used to produce the plots is mc16_13TeV.346678.aMcAtNloPythia8EvtGen_tWH125_4fl_CPalpha_0.deriv.DAOD_TOPQ1.e7816_a875_r9364_p4514/DAOD_TOPQ1.27722941._000003.pool.root.1

This implementation is needed by the tH(bb) boosted CP analysis as soon as possible.

Tagging analysis contacts and experts: @vvecchio @brle @mfoti @thsteven @cabrera


Edited by Mohamed Aly

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