CandPtrProjector unclustered candidate matching for MET NoHF (bug in miniAOD MET NoHF)

[slava77]

I was debugging differences in UL re-miniAOD between 106X and 112X, and was puzzled by the somewhat small but numerous changes in slimmedMETsNoHF UnclusteredEnUp/Down.
If I understood correctly (although I did not add any debug printouts to confirm), the problem is that the "NoHF" is based on noHFCands, which are copies (not Ptrs) of the original PF cands

cmssw/CommonTools/ParticleFlow/interface/GenericPFCandidateSelectorDefinition.h

Lines 31 to 34 in 3402e09

	if (selector_(*pfc)) {
	selected_.push_back(reco::PFCandidate(*pfc));
	reco::PFCandidatePtr ptrToMother(hc, key);
	selected_.back().setSourceCandidatePtr(ptrToMother);

So, the CandPtrProjector can not match the vetoing electron's sourceCandidatePtr (the original particleFlow) to the noHFCands (another check by the cand's sourceCandidatePtr may suffice though).

So, either we

• need an extension in CandPtrProjector to also check for the main collection sourceCandidatePtr
• or instead have useDeltaRforFootprint = True for all MET variants with copied candidates;
• or make noHFCands to be Ptrs

@ahinzmann @camclean @alefisico

[slava77]

assign reconstruction

[cmsbuild]

New categories assigned: reconstruction

@slava77,@perrotta,@jpata you have been requested to review this Pull request/Issue and eventually sign? Thanks

[cmsbuild]

A new Issue was created by @slava77 Slava Krutelyov.

@Dr15Jones, @dpiparo, @silviodonato, @smuzaffar, @makortel, @qliphy can you please review it and eventually sign/assign? Thanks.

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[slava77]

+1

fixed in #31212
(merged on Aug 25)

[cmsbuild]

This issue is fully signed and ready to be closed.