Extra Exercises

Overview

Teaching: 0 min
Exercises: 100 min

Questions

• Did you find the previous portions of the pre-work easy? Care to take it a next step?

Objectives

• Think more about the experimental aspects of the physics that we are investigating. How to the charged leptons come into play?

• Make our code adhere to some ATLAS coding standard by checking for errors.

• Examine what we find if we execute our analysis on some background samples.

Additional Exercises

If you found the previous exercises and setup too easy then here is a list of other tasks to try if you get time before the computing bootcamp.

Exercise 1

Adapt the AnalysisPayload.cxx code so that it only considers jets in the event that pass some minimum jet->pt() requirement of 50 GeV, and are within std::abs(jet->eta())<2.5. If this is easy, then write a configuration file and a parser that will allow you to configure these selection criteria. While you are at it, make this configuration file read in the path to the input file that you want to analyze.

Exercise 2

Put in success checks throughout the AnalysisPayload.cxx code where they are needed to avoid errors and exceptions. The details of what these are and how to use them can be found here - Return Codes (a.k.a. Status Codes). There should be an unchecked status code counter at the end of your output as a hint of where they might be.

…

Jet : 19045.4-0.4281811.751874285.59

Jet : 15588.91.74852-1.104962493.13

xAOD::TFileAccessTracer INFO Sending file access statistics to http://rucio-lb-prod.cern.ch:18762/traces/

Warning in <xAOD::TReturnCode>:

Warning in <xAOD::TReturnCode>: Unchecked return codes encountered during the job

Warning in <xAOD::TReturnCode>: Number of unchecked successes: 114686

Warning in <xAOD::TReturnCode>: To fail on an unchecked code, call xAOD::TReturnCode::enableFailure() at the job’s start

Warning in <xAOD::TReturnCode>:

…

Exercise 3

Because this is a ZH process, where the Z boson decays to two charged leptons, there are not only xAOD::Jets in the event. If you inspect your input DAOD file, you will also find that there is are xAOD::Electrons and xAOD::Muons containers. Try to retrieve these in a similar way as the jets (but this time calling them xAOD::Electrons and xAOD::Muons). You may need to refer to the EDM to learn about the xAOD::Egamma and xAOD::Muon classes.

Try printing out the number of electrons and muons in a given event. What do you notice? Does it make sense?

Now, if all of this makes sense and is relatively easy, here comes the kicker. Experimentally ELECTRONS ARE JETS!!! They show up in the calorimeter as blobs of energy. Can you confirm this by studying the spatial/angular (eta,phi) separation between electrons and jets in a given event. In the case that you have two muons and not two electrons, the situation even gets and you should be sure to bring it up at the bootcamp.

Exercise 4

Get another file from the grid and run over that instead. As a suggestion, try running over one of the samples which is a very challenging (i.e. “irreducible”) background in the ZH search. This is the standard model production of a Z boson which decays to two electrons produced in association with b quarks (see that BFilter in the name?).

mc16_13TeV.364122.Sherpa_221_NNPDF30NNLO_Zee_MAXHTPTV140_280_BFilter.deriv.DAOD_EXOT27.e5299_s3126_r9364_p3840

Can you find the jobOptions that were used to produce this DAOD?

Key Points

• Writing good code requires care, especially when it gets complicated.

• Using configuration files allows us to compile our code less frequently.

• The search for VH(bb) is hard!