Fix ParticleCombinations from decayProducts

Particle combinations with 7 or 8 particles have wrong indices. This is fixed here. Also mass2 in the ParticleCombination class is changed to not use the measuredMass method of Particle.

not dependent on but related to Rec!2762 (merged) and DaVinci!666 (merged)

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assigned to @gunther

@graven I've stumbled over this when trying to understand why the F.SUBCOMB(Functor=F.MASS, Indices=[1, 2]) functor does not work in DaVinci despite it looking like all the code functionality is there. When cling tries to compile the functor it complains about

Rec/InstallArea/x86_64_v3-centos7-gcc11-opt+g/include/Functors/Composite.h:402:20: error: no matching function for call to 'mass2'
      return sqrt( mass2( Sel::Utils::deref_if_ptr( particle ) ) );

then looking a bit into the code I got confused because ParticleCombination has a copy in Rec/Phys/SelKernel/include/SelKernel. Why is that? From what I understand calling SUBCOMB on a Composite in DaVinci returns a ParticleCombination as defined in Event/ParticleCombination.h which does not have the needed friend mass2 function, however, adding it also does not solve the compilation error. This kind of makes sense as the compiler seems to not get which subCombination specialisation to take in the first place - it then uses the one from SelKernel/Utilities.h which defines IndirectRange as return value and is a dead end here for me. Do you have some insight for me on this?

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• 887b86bc...565e8884 - 8 commits from branch master
• bb5add4a - fix particle combination in decayProducts

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@sstahl for ( auto* i : m_children ) { energy += sqrt( pow( i->p(), 2 ) + pow( i->measuredMass(), 2 ) ); } let's discuss this here. I see that measuredMass is probably not he best choice here. But are the momenta of the children updated after the vertex fit?

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• 6a5ff5e0 - simplify mass2

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assigned to @peilian

mentioned in merge request Rec!2762 (merged)

• [2022-03-01 17:23] Validation started with lhcb-master-mr#3831
• [2022-03-04 08:53] Validation started with lhcb-master-mr#3864

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• cbf44527 - use fourMomentum

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assigned to @rmatev and unassigned @gunther and @peilian

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mentioned in commit Moore@29e0b948

mentioned in merge request Moore!1405 (merged)

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mentioned in issue Moore#397 (closed)

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