Information related to Z counting to determine ATLAS luminosity

Useful Links

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ATLAS ZCounting twiki - https://twiki.cern.ch/twiki/bin/viewauth/Atlas/ZCountingLumi
ATLAS Luminosity Group - https://twiki.cern.ch/twiki/bin/view/Atlas/LuminosityGroup
Source code - https://gitlab.cern.ch/atlas/athena/tree/21.0/DataQuality/ZLumiScripts/scripts
Luminosity for Physics - https://twiki.cern.ch/twiki/bin/viewauth/Atlas/LuminosityForPhysics
ATLAS Lumi Calculator - https://atlas-lumicalc.cern.ch/
Activate Cernbox. Then accessible via /eos/user/m/miokeefe/ for example - https://cernbox.cern.ch/

Example Job

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Example job can be found in:

See README for description of directory and code structure.

MC samples

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Special high mu Zmumu

mc16_13TeV.361107.PowhegPythia8EvtGen_AZNLOCTEQ6L1_Zmumu.merge.AOD.e3601_s3126_r9425_r9315

Standard MC16a samples (matching 2015+2016 data)

mc16_13TeV.361106.PowhegPythia8EvtGen_AZNLOCTEQ6L1_Zee.merge.AOD.e3601_s3126_r9364_r9315

mc16_13TeV.361107.PowhegPythia8EvtGen_AZNLOCTEQ6L1_Zmumu.merge.AOD.e3601_s3126_r9364_r9315

Standard MC16c samples (matching 2017 data) [Now Redundant]

mc16_13TeV.361106.PowhegPythia8EvtGen_AZNLOCTEQ6L1_Zee.merge.AOD.e3601_s3126_r9781_r9778

mc16_13TeV.361107.PowhegPythia8EvtGen_AZNLOCTEQ6L1_Zmumu.merge.AOD.e3601_s3126_r9781_r9778

Standard MC16e samples

mc16_13TeV.361107.PowhegPythia8EvtGen_AZNLOCTEQ6L1_Zmumu.recon.AOD.e3601_s3126_r10724

mc16_13TeV.361106.PowhegPythia8EvtGen_AZNLOCTEQ6L1_Zee.recon.AOD.e3601_s3126_r10724

Running over MC

Same as on ZCounting twiki above, however only the dqt_zlumi_alleff.py script can be run. The luminosity cannot be computed, only the efficiencies.

Trigger info

https://twiki.cern.ch/twiki/bin/viewauth/Atlas/LowestUnprescaled

Workflow

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Idea is:

• Use the 2016 example run (304008) and monitor all steps (e.g. T&P efficiency) versus LB.

Long term goal is:

• Understand syst uncertainties in Z counting related to muons, which are:
  • T&P: stats dominated, need proper treatment to avoid double counting of stats errors.
  • Muon calibration.
  • Alignment L time-dependent? Some alignment is done already in calibration loop before full data processing - sufficient?

Tasks / ongoing investigations:

• Last update: January 29, 2018 (after discussion with Peter Onysi at CERN)
• Understand the cuts applied: isolation, pT, eta, impact parameter cuts - nominal selection so far should be pT>27 GeV, |eta|<2.4 for both muons (can we find these selections in the code?), may need to raise pT cuts for 2018 depending on lowest unprescaled triggers available
• Which efficiencies are applied: trigger, muon reconstruction; should aim to monitor also track efficiency and consider making T&P efficiency differential
• How are those efficiencies calculated: Monitor and plot those efficiencies for an example run for learning - see slides by Harry, excursions are likely low statistics bins where also background subtraction carries large uncertainties (and may lead to efficiency > 1? - to be checked)
• Where is MC used for corrections:
  • this should be part of the mu-dependent "MC non-closure" (this encapsulates all effects we cannot determine purely from data, thus "non-closure" may be somewhat misleading) -- however seems this is "correcting" back to total cross section mll>60 GeV, not useful for fiducial cross sections (and maybe not ideal to compare "fiducial Zs with CMS")
  • To investigate: QED FSR is properly taken into account, find place where truth-level selection is performed, run MC (technical hurdle: many "duplicated" histograms created when running on MC, need to run small pieces and learn how to merge this efficiently - Michael with test the command "DQ histogram merge")
• How (if at all) are mu corrections applied: implicitly in T&P efficiencies, mu-dependend "MC non-closure"
• Where is official lumi coming from in the plot, and is it really the latest one?
• Implement procedure to control that all events (lumi blocks) were processed (or alternatively correct expected luminosity accordingly) - missing pieces in Michael's plots got filled on rerunning jobs on the grid
• Usage of GRL: typically will run with a very preliminary GRL from the beginning and then later with the official GRL for the final result
• Understand the used "acceptance" (0.3323) and theoretical Z cross section
• Fine tuning:
  • understand if assumption SameSign events = Opposite Sign background is justified
  • is there a correlation of statistical errors of reconstruction and trigger efficiencies?

Schedule

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Times not available for meeting

Michael:

• Mon - 1-3 pm
• Tue - 2-5 pm
• Wed -
• Thur - 11-1 pm
• Fri - 9-11 am

Jan:

• Tue 9am - 5 pm most weeks
• Wed 1.30pm-4pm most weeks
• Fri 1pm-3pm

Harry:

• Tuesday 9am-12
• Thursday 10am-5pm (Starting Week 7)

Indico

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https://indico.cern.ch/category/10219/

Documentation

https://www.overleaf.com/15188538qvkqrfkjcspn

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Contributors: Michael O'Keefe, Harry Lyons, Uta Klein, Jan Kretzschmar, Max Klein

-- JanKretzschmar - 12 Jan 2018