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Heppy_-_Full_analysis_workflows.md

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Full analysis workflows

This section presents heppy analysis sequences that are used in real experiments, present or future.

Understanding heppy configuration files

All examples below are implemented in a specific configuration file like analysis_ee_ZH_cfg.py.

These files are self documented, just open these files and read the inline comments.

To get more information on one of the objects used in these files, start python or ipython and use the python help function, e.g.,

from analysis_ee_ZH_cfg import *
help(ResonanceBuilder)
Help on class ResonanceBuilder in module heppy.analyzers.ResonanceBuilder:

class ResonanceBuilder(heppy.framework.analyzer.Analyzer)
 |  Builds resonances.
 |
 |  Example:
 |
 |  from heppy.analyzers.ResonanceBuilder import ResonanceBuilder
 |  zeds = cfg.Analyzer(
 |    ResonanceBuilder,
 |    output = 'zeds',
 |    leg_collection = 'sel_iso_leptons',
 |    pdgid = 23
 |  )
 |
 |  * output : resonances are stored in this collection,
 |  sorted according to their distance to the nominal mass corresponding
 |  to the specified pdgid. The first resonance in this collection is thus the best one.
 |
 |  Additionally, a collection zeds_legs (in this case) is created to contain the
 |  legs of the best resonance.
 |
 |  * leg_collection : collection of particles that will be combined into resonances.
 |
 |  * pdgid : pythia code for the target resonance.
 |
 |  See Resonance2 and heppy.particles.tlv.Resonance for more information
 |
 |  Method resolution order:
 |      ResonanceBuilder
 |      heppy.framework.analyzer.Analyzer
 |      __builtin__.object
 |
 |  Methods defined here:
 |
 |  process(self, event)
 |
 |  ----------------------------------------------------------------------
 |  Methods inherited from heppy.framework.analyzer.Analyzer:
 |
 |  __init__(self, cfg_ana, cfg_comp, looperName)
 |      Create an analyzer.
 |
 |      Parameters (also stored as attributes for later use):
 |      cfg_ana: configuration parameters for this analyzer (e.g. a pt cut)
 |      cfg_comp: configuration parameters for the data or MC component (e.g. DYJets)
 |      looperName: name of the Looper which runs this analyzer.
 |
 |      Attributes:
 |      dirName : analyzer directory, where you can write anything you want
 |
 |  __str__(self)
 |      A multipurpose printout. Should do the job for most analyzers.
 |
 |  beginLoop(self, setup)
 |      Automatically called by Looper, for all analyzers.
 |
 |  endLoop(self, setup)
 |      Automatically called by Looper, for all analyzers.
 |
 |  write(self, setup)
 |      Called by Looper.write, for all analyzers.
 |      Just overload it if you have histograms to write.
 |
 |  ----------------------------------------------------------------------
 |  Data descriptors inherited from heppy.framework.analyzer.Analyzer:
 |
 |  __dict__
 |      dictionary for instance variables (if defined)
 |
 |  __weakref__
 |      list of weak references to the object (if defined)

FCC: ee → ZH → μμ bb

At the FCC-ee and at the ILC, Higgs bosons are produced through the ee → ZH process. The center-of-mass energy is set to 240 GeV. Signal events are selected by requiring two isolated muons. The mass of the two-muon system is required to be compatible with the Z mass. The Higgs four momentum is typically not reconstructed from the Higgs decay products, but as the difference between the initial p4 and the Z p4. A given Higgs decay channel can be selected by identifying the particles present in the final state in addition to the two muons, e.g. b jets or τ leptons.

The sequence is described in the configuration file analysis_ee_ZH_cfg.py. It consists in the following steps:

Simulation and reconstruction:

  1. read generated particles from an FCC-ee event sample
  2. run the stable gen particles through a simulation of the CMS detector in papas.

Analysis:

  1. select leptons of a given type (either electron or muon)
  2. compute lepton isolation
  3. select isolated leptons
  4. build Z candidates from the list of selected leptons, and choose the Z with the mass closest to mZ.
  5. compute the four-momentum of the particles recoiling against the Z.
  6. compute the missing four-momentum.
  7. remove the leptons corresponding to the selected Z from the list of particules, and reconstruct two exclusive jets
  8. build a higgs candidate from the two jets
  9. fill a simple cut-flow table
  10. fill a tree (ntuple)

FCC-hh pp → H → 4 leptons

To be written.

FCC-hh pp → t tbar

To be written