this MR includes several features required by the H->ZZ->4L analysis into
DAOD_PHYS to add this ATLAS flagship as another user of the common format. The common features are:
- The refit of the selected electron muon pairs to a common vertex. The vertices of all four-lepton combinations are saved to the
FourLeptonVericescontainer. The covariances and the track weights are pruned from the containers to save a massive chunk of the needed disk space. The lepton selection criteria are documented in !56388 (merged). The physics performance of the vertex fit has been extensively validated
and the selection efficiency on the vertex quality at analysis level was found to be 99.95%. To assess the size increase due to the extra container, derivations from a data18 sample and several simulation samples were made. The table below summarizes the outcome from the
checkxAOD macros. Even in the signal sample, the container needs roughly 0.01kB per event corresponding to a total size fraction of way below 1%.
|Sample||#events||Mem Size||Disk Size||Size/Evt||Compression||Fracion of DAOD|
|Data||28862||5483.877 kb||149.372 kb||0.005 kb||36.713||0.%|
|ttbar||30000||5730.793 kb||166.952 kb||0.006 kb||34.326||<0.007%|
|qq->ZZ||30000||6215.175 kb||276.931 kb||0.009 kb||22.443||<1%|
|Higgs||40000||10776.627 kb||804.082 kb||0.020 kb||13.402||<1%|
- HTXS characterization model: This part adds several decorations to the
xAOD::EventInfoin simulated samples to assess the Higgs production mode. The characterization is used by a wider range of Higgs analyses than the 4L channel.
- All samples: Add
HTXS_prodModedecoration stating whether this is a signal sample of interest.
- List of samples mentioned in HiggsMCsamples.cfg: Full characterization of the Higgs events encoded in 18 integer, 8 float and 16 float vector decorations.
- Information needed by the isolation close by correction tool: The idea of this tool has been floating around since the early days of the LHC. If two leptons from a Higgs decay are collimated enough, their associate tracks and calorimeter clusters would pollute the isolation variable of the other one. (Cf. the left plot below). The tool does nothing else than finding these pairs and subtract the energy of the associated id-track or Calo cluster (Cf. the right plot - please note that these one have been made ages ago, but they should satisfy the illustration purposes here)
I've opened another MR (!55961 (merged)) to update the tool to the area of release 22. It includes 2 algorithms which shall run at derivation level and do the following:
IsoCloseByCorrSkimmingAlg searches for close-by lepton pairs. It adds the ID track of the lepton to the derivation if it pollutes the isolation variables of another lepton. The screen prompt below states the number of accepted tracks in the Higgs signal,
--- Muons: 2664 out of 70729 (3.76649%). --- Electrons: 3261 out of 61003 (5.34564%).
the ttbar sample
--- Muons: 1275 out of 24658 (5.17074%). --- Electrons: 833 out of 16634 (5.00782%).
--- Muons: 1713 out of 15586 (10.9906%). --- Electrons: 462 out of 8407 (5.49542%).
To correct the calorimeter isolation, the current plan is to decorate the electrons with the Eta/Phi/E of the associated Pflow elements. To ensure that the tool is actually run, another char decorator is added. For the muon case, we will likely add these decorations too, plus 2 extra ones containing the average eta/phi of the muon in the calorimeter. Maybe, we can get rid of the MuonCaloClusters then, if they are not already trashed in