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HLT b-tagging for hadronic top analysis

How it works

Basically, if you look for example at btag_quad25_MC_trigger.py, in process.HLT_BTagIP_QuadJet25U_test you have first of all a filter on L1 trigger QuadJet8U (process.hltL1sL1QuadJet8U), than you run the reco jet sequence and ask for 4 jets with pt>25GeV/c (hlt4jet25U). At this point you run the L2.5 (pixel only) and L3 (full regional tracking) b-tagging sequence on the first 4 jets of the event and ask for at least one tagged jet (you can tune this value in the module hltBLifetimeL25FilterStartupU). The main parameters of interest to compute the tag are in the trackIPproducer hltBLifetimeL3(L25)TagInfosStartupU and in the jettagproducer hltBLifetimeL3BJetTagsStartupU, where you can choose the minimum number of hits, the minimum number of pixel hits, the track to use to compute the IP significance and so on. I think the modules you are interested in are the ones to make the regional tracking, so basically hltBLifetimeRegionalCkfTrackCandidatesStartupU and hltBLifetimeRegionalPixelSeedGeneratorStartupU.

You can't find PerformanceStudies.btaghlt_cfi because it's a package I wrote to study the efficiency of this trigger. It's an analyzer that runs on top of this trigger, so you can skip it (sorry I forgot to delete it from the sequence).

Last thing. The .py to run on data misses the filters on the IP at L25 and L3. You can copy paste them (hltBLifetimeL3(25)FilterStartupU) from the other file.

Recipe for reproducing the b-tagging at HLT with v9.4 HLT menu

To reproduce the IP based b-tagging at the HLT level with this menu we just have to follow these steps:
  • cmsrel CMSSW_3_9_0
  • cvs co HLTrigger/HLTfilters
  • cvs co HLTrigger/JetMET
  • cvs co -r V00-07-00 TrackingTools/Producers
  • run the cfg at the following path: /afs/cern.ch/user/t/tropiano/scratch0/CMSSW_3_9_0/src/offline_data.py

Timing studies

To run the official timing studies software one should first produce a skimmed rootuple, with just the FEDRawDataCollection stuff.

You can find it here: /afs/cern.ch/user/t/tropiano/scratch0/CMSSW_3_9_0/src/TimingSkim.py

-- AntonioTropiano - 30-Oct-2010

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Topic revision: r5 - 2010-12-01 - AntonioTropiano
 
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