Liverpool DiPhoton Group

In order to co-ordinate the groups diphoton activities, a mini group (Helen Hayward, Steve Maxfield and Barry King) has been formed to collaborate on various (di)photon activities with the aim of making an impact in GMSB and exotic diphoton searches

Tasks

• Finish Susy Csc08 note (link to atlas gmsb twiki page) - Helen editor of non-pointing section
• comparison of various diphoton generators - Barry contributing to dilepton/diphoton note
  • Steve to chase Samir for names of generators
• single particle gun, neutralino in full sim ?
• Look into improving reconstruction/identification of nonpointing photons : barry
• write talk on fate rate Trash/CDF history and plans - Helen's talk to dilepton/diphoton group.
• investigate possible Fqcd methods at ATLAS ?
  • conversions
  • presampler - limited depth, depth varies with eta
  • 1st sampling layer.... analyse shower profile
  • isolation
• Meet with Daniel F - Helen and Barry 24th Feb.
  • What is the H->gammagamma presampler method ??
• Is there a clever way to combine Zprime and timing info for neutralino lifetime extraction ? - Steve ?
• Can we use conversion probability to estimate distance travelled ?
• Can we estimate energy of neutralino somehow ?

Choice of Analysis Framework

suggestions + links:

• Skim/Slim/Thin
  • TAG to create a reduced size AOD file
  • TAG for event selection
  • create DPD file:
    • via EventView
    • standalone example (any documentaion?)
    • Some useful talks
• AthenaROOTAccess To start?
  • Standalone from Athena ->
  • Detailed cell info not available -> is this ok ?
• November tutorial: covers both DPD and AthenaROOTAccess

Meetings

• Meeting with Daniel Froideveaux 24th Feb (H+B)

• • concentrate on seperating pi0 and photons, 4 possible methods: conversions, presampler, 1st sampling (shower profile) and isolation
  • in v13, only etcone20 is present - more choice in v14, but we should ask for it to make sure.
  • There will be a group effort at cern looking at fakes (guiliamme unal)
  • DF asks whether we can do this work under the umbrella of the egamma group.
  • in version 13, the reclustering of egamma objects on the AOD has not been validated... photon clustering uses 5x9. also hits on trackes available.

Helen's notes

• Multivariate analysis for neutralino lifetime
  • MLPfit as used by Ben Kilminster for jet energy scales
  • Pssibly already implimented in root ?
  • pssible higgs example?

Steve's notes

• Exotics working group meeting schedule (includes Dilepton/Diphoton sub-group meetings): Link to Exotics meetings
• Dilepton/Diphoton subgroup Twiki: CSC note stuff

• Samir's Intro to19th Dec Dilepton/diphoton meeting
  • (Contains list of topics to be pursued post CSC note)

On Fake Rates

Here are links to some recent talks etc. on fake rate estimation.

• Talk given at November 07 Trigger and Physics Week to the Higgs working group:
  • H->gamma gamma
• Almost nothing at higher Pt. this from October 23rd CSC exotics Dilepton/Diphoton meeting:
  • Diphoton Update
• The CSC note covering this from the exotics perspective is here:
  • CSC note 15/01/08
  • (The relevant section is 3.3.3)
• Available single particle datsets are located :
  • here, (select perf-egamma, and search for "single" and "AOD" mainly 13.0.30 and only one single pi0 sample (25 GeV)
  • Egamma twiki page listing datasets

Diphoton generators etc.

* The DIPHOX home page can be found : here * ...and RESBOS: here

The comparison of RESBOS and DIPHOX generators, again in the lower energy context of H->GammaGamma was discussed in this talk from the November T&P week:

• RESBOS and DIPHOX

Here are some papers referenced in the above talk:

• RESBOS and DIPHOX Compared
• (original?) DIPHOX paper
• Diphoton production at the LHC (2003)

Barry's notes

-- HelenHayward - 14 Jan 2008