Alternatively, using the ICHEP ntuples:

%CODE{ lang="sh"}%

export ATLAS_LOCAL_ROOT_BASE=/cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase alias setupATLAS='source ${ATLAS_LOCAL_ROOT_BASE}/user/atlasLocalSetup.sh' setupATLAS --quiet

setupATLAS mkdir PlotFactory _MayProduction_20.7_devbranch cd PlotFactory _MayProduction_20.7_devbranch export AnalysisTopVersion ="2.4.16" rcSetup Top,"${AnalysisTopVersion}"

rc checkout_pkg svn+ssh://aalshehr@svn.cern.ch/reps/atlas-aknue/GlaProjects/PlotFactoryBoosted/devbranches/PlotFactoryBoosted_ttH_20.7/ rc checkout_pkg atlasoff/PhysicsAnalysis/TopPhys/TopPhysUtils/TopDataPreparation/trunk

rc find_packages rc compile

%CODE{ lang="sh"}%

export ATLAS_LOCAL_ROOT_BASE=/cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase alias setupATLAS='source ${ATLAS_LOCAL_ROOT_BASE}/user/atlasLocalSetup.sh' setupATLAS --quiet

setupATLAS mkdir PlotFactory _MayProduction_20.1_devbranch cd PlotFactory _MayProduction_20.1_devbranch AnalysisTopVersion ="2.3.45a" rcSetup Top,"${AnalysisTopVersion}"

rc checkout_pkg svn+ssh://azzahusername@svn.cern.ch/reps/atlas-aknue/GlaProjects/PlotFactoryBoosted/devbranch/PlotFactoryBoosted_ttH_20.1/ rc checkout_pkg atlasoff/PhysicsAnalysis/TopPhys/TopPhysUtils/TopDataPreparation/trunk rc checkout_pkg atlasoff/PhysicsAnalysis/TopPhys/xAOD/TopFakes/tags/TopFakes-00-00-08

rc find_packages rc compile

%ENDCODE%

4. Make a complete set of control plots for all resolved ttH analysis regions

For this you will need to run plot factory:

The studies to be carried out (and those already completed) are included in this twiki:

1. Understanding the KLFitter performance in ttbar events

2. Extending KLFitter to be used with ttH events

3. Understanding the ttH analysis strategy through review of the Run-1 publication

For the first results, the 13TeV ttH analysis will follow the Run-1 ttH analysis very closely. Therefore, having a very thorough understanding of the 8TeV analysis is crucial for successfully completing the tasks outlined in your thesis plan. For this reason, we recommended studying the 8TeV ttH analysis very carefully. Having carried out this review, you will be able to give a presentation about ttH analysis in a Glasgow ATLAS meeting.

List of questions to answer

Here is a list of questions designed to guide you to what are the most important points to understand about the analysis: TTH_Questions.pdf

The list is not complete but covers most of the important points. Prepare a document with your answers to these questions in a LaTeX document, as you will certainly find this a useful thing to refer back to in the future.

Run-1 ttH analysis Links

Run-1 ttH analysis Links

paper: http://arxiv.org/abs/1503.05066

conf note: https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2014-011/

int note: https://cds.cern.ch/record/1638000/files/ATL-COM-PHYS-2013-1659.pdf?

Update to newer versions of the samples and repeat the KLFitter study

• Get a newer derivation of the ttbar sample (mc15_13TeV.410000.PowhegPythiaEvtGen_P2012_ttbar_hdamp172p5_nonallhad.merge.DAOD_TOPQ1.e3698_s2608_s2183_r7267_r6282_p2516/)
• Make the plot comparing the efficiencies for the different sets of jets (as above) with this sample and compare to what you had before. Make sure you use sufficient statistics.
• Does your conclusion change?

Efficiency of reconstructing the rest of the event

Now you have measured the efficiency of reconstructing the hadronic top correctly, you can do the same for the leptonic top and for both:

• What is the efficiency for reconstructing the leptonic top in the events?
• What is the efficiency for reconstructing both the hadronic and leptonic tops?

Reconstruction efficiency in ttH events

We would like to know what the efficiency of reconstructing the tops in ttH events using exactly the same KLFitter technique as you did in ttbar:

• Download a few files of the ttH sample: mc15_13TeV.341270.aMcAtNloHerwigppEvtGen_UEEE5_CTEQ6L1_CT10ME_ttH125_semilep.merge.DAOD_TOPQ1.e4277_s2608_s2183_r6869_r6282_p2516/
• What is the reconstruction efficiency for the hadronic top in these events
• Also, measure the efficiency of reconstructing the leptonic top and then both the hadronic and leptonic tops together.

• Change the jets used by KLFitter to perform the reconstruction by requiring that is using one or two b-jets for example (investigate the different possibilities)

What is the effect on the KLFitter reconstruction efficiency of changing the set of jets in >=4 jets, >=2 b-tags?

• Investigate how to change the set of jets to give to KLFitter using twikis and documentation
• Change the jets used by KLFitter to perform the reconstruction by requiring that is using one or two jets (depending on the findings of the study above)
• Find the reconstruction efficiency as you did before and compare with the results of using KLFitter in the default configuration.

What is the change in efficiency for 4 matches when we require b-tagged jets in the event selection?

• Change the event selection in cuts.txt to require at least one b-tagged jet (>=4 jets, >=1 b-tags)
• Calculate the efficiency of 4 matches, 3 matches, 2 matches, 1 match and no matches in these events.
• Change the event selection in cuts.txt to require at least two b-tagged jets (>=4 jets, >=2 b-tags)
• Calculate the efficiency of 4 matches, 3 matches, 2 matches, 1 match and no matches in these events.

What is the effect (on matching efficiency) of changing the set of jets in >=4 jets, >=2 b-tags?

Even in events with >=4 jets, >=2 b-tags, if we consider only the first 4 jets (in order of pT) then there will be times where we are not using the b-tagged jets in KLFitter. This is because they may be the 5th or 6th jet in pT. Since we are studying the best set to give to KLFitter, it might be better to choose the set in another way. Next you should study the efficiency of 4 matches, 3 matches, 2 matches, 1 match and no matches for different choices of sets of jets.

• Select events with >=4 jets, >=2 b-tags using cuts.txt.
• Using this ntuple, repeat the study above for a different set of 4 jets, e.g.

• Make a histogram of the number of matches per event

Overview

1. Understanding the KLFitter performance in ttbar events
2. Extending KLFitter to be used with ttH events

Understanding the KLFitter performance in ttbar events

How often do we give the correct jets to KLFitter?

• For the 4 leading jets in the event, access the "jet_truthmatch" variable for each one and count how many matches you have to the decay products of the tops. You can find more information about the variable here.
• Make a histogram of the number of matches per jet
• Calculate the efficiency of having all 4 jets matching a decay product from the top.
• Calculate the efficiency of 3 matches, 2 matches, 1 match and no matches.

Is there a better set of jets to give to KLFitter?

We currently use the leading 4 jets (in order of pT) as input to KLFitter. Are there other sets of 4 jets which would give us a higher efficiency for 4 matches (as measured above). Repeat the study above for different set of 4 jets, e.g.

• 1 leading (in pT) b-tagged jet + 3 more jets (highest in pT, b-tagged on not)
• 2 leading (in pT) b-tagged jets + 2 more jets (highest in pT, b-tagged on not)
• Any other options you can think of!

Extending KLFitter to be used with ttH events

Adjust KLFitter likelihood

Plans and To-Do list

Article text.

To-do list

Useful Links

AnalysisTop: https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/TopxAODStartGuide

TTHbbLeptonic SVN: https://svnweb.cern.ch/cern/wsvn/atlasphys-hsg8/Physics/Higgs/HSG8/AnalysisCode/

TTHbbLeptonic twiki: https://twiki.cern.ch/twiki/bin/view/AtlasProtected/TtH_Run2_Analysis_FrameWork

KLFitter paper: http://arxiv.org/abs/1312.5595

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