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2013:groups:tools:eventformats

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Event Format : extended LHE

People involved:

Present state

Sample size: example of ttbar dileptonic @ LHC (10,000 events)

File size (Mo)
LHE (gzip compression) 3.8
STDHEP (gzip compression) 153
HEPMC (gzip compression) 346
simplified LHE (gzip compression) 5.1
LHCO (gzip compression) 1.6
Delphes ROOT 161

Motivations

  • defining a format for jet-clustering output (without fast-simulation detector).
  • defining a format which extends the LHCO content (too few information for performing sophisticated analysis).
  • the new format will take into account all Delphes 3 potential.

Some ideas to discuss

  • Using text format. ROOT is rejected ; STDHEP seems to be old.
  • Prefering extending an existing format to defining a totally new one (avoiding developers from coding writer and reader functions from scratch). Our choice is to extend the LHE Format (arXiv:hep-ph/0609017) and its structure based on XML tags. Reminder about the LHE structure:
<LesHouchesEvents version="X">
<header>
...
</header>
<init>
2212     2212  0.40000000000E+04  0.40000000000E+04 0 0 10042 10042 3  1
0.47468358499E+01  0.15068796356E-01  0.47469000000E-03   0
...
</init>
<event>
 12   0  0.4746900E-03  0.2312331E+03  0.7957747E-01  0.1132798E+00
 21   -1    0    0  501  502  0.00000000000E+00  0.00000000000E+00  0.74064204368E+02   0.74064204368E+02  0.00000000000E+00 0.  1.
 21   -1    0    0  502  503  0.00000000000E+00  0.00000000000E+00 -0.74552086368E+03  0.74552086368E+03  0.00000000000E+00 0.  1.
 -6    2    1    2    0  503  0.14952840473E+03 -0.23999735524E+02 -0.41424800778E+03  0.47441561784E+03  0.17473990778E+03 0.  0.
-24    2    3    3    0    0  0.56722398399E+02 -0.36860071438E+02 -0.33540004381E+03  0.35186997544E+03  0.82116958530E+02 0.  0.
  6    2    1    2  501    0 -0.14952840473E+03  0.23999735524E+02 -0.25720865153E+03  0.34516945021E+03  0.17335203433E+03 0.  0.
 24    2    5    5    0    0 -0.16699616992E+03  0.38357854935E+02 -0.25987491067E+03  0.32192128147E+03  0.82093218139E+02 0.  0.
-13    1    6    6    0    0 -0.76026472087E+02  0.53922169130E+02 -0.95737952146E+02  0.13361654188E+03  0.00000000000E+00 0.  1.
 14    1    6    6    0    0 -0.90969697833E+02 -0.15564314195E+02 -0.16413695853E+03  0.18830473960E+03  0.00000000000E+00 0. -1.
  5    1    5    5  501    0  0.17467765185E+02 -0.14358119410E+02  0.26662591415E+01  0.23248168736E+02  0.46999998093E+01 0. -1.
 11    1    4    4    0    0  0.50813684997E+02 -0.61274565657E+02 -0.22556131392E+03  0.23919554619E+03  0.00000000000E+00 0. -1.
-12    1    4    4    0    0  0.59087134026E+01  0.24414494219E+02 -0.10983872989E+03  0.11267442925E+03  0.00000000000E+00 0.  1.
 -5    1    3    3    0  503  0.92806006335E+02  0.12860335914E+02 -0.78847963972E+02  0.12254564240E+03  0.46999998093E+01 0.  1.
</event>
<event>
...
</LesHouchesEvents>
  • Extending the LHE format in order to store partons, hadrons and jets (reco objects) in a same file. The generation step (hard-process, shower, reco) will be specified by the status-code. Some details:

  • parton level: same conventions than the existing LHE. Example:
6    2    1    2  501    0 -0.14952840473E+03  0.23999735524E+02 -0.25720865153E+03  0.34516945021E+03  0.17335203433E+03 0.  0.
  • hadron level: the conventions can be applied without too much change (maybe the meaning of the two ICOLUP variables could be discussed).
2212    2    1    2  501    0 -0.14952840473E+03  0.23999735524E+02 -0.25720865153E+03  0.34516945021E+03  0.17335203433E+03 0.  0.
  • reco level: the conventions have to be adapted. We can keep:
    • one line per physics object.
    • ISTUP variable with specific PDG-id for reco objects. Example: 11/-11 for electrons, 13/-13 for muons, 15/-15 for hadronically-decaying taus, 22 for photons, 21 for jets, 12 for MET, -12 for MHT
    • MOTHUP variables linked the reconstructed object to the originated partons (only for some objects). Example: a electron coming from hard-process.
    • PUP variables without change.

Other relevant variables, specific to the nature of the reconstructed objects, must be added.


  • Optional substructure in <event> block: defining a XML tag for each collection of reconstructed objects. When detector fast-simulation is applied, several configurations can be applied (for instance for lepton isolation) and several collection of the same object kind can be produced. The <event>-block substructure is designed to handle several collections of a same object kind. Example:
<event>
...

<jets>
...
</jets>
<jets name="substructure John Hopkins algo">
...
</jets>
<electrons>
...
</electrons>
<muons>
...
</muons>
</event>
2013/groups/tools/eventformats.1371716685.txt.gz · Last modified: 2013/06/20 10:24 by eric.conte