You'll need to apply the following MC corrections for electrons:

- SFs for reco, ID, trigger, and additional cuts
- crack energy calibration
- atlfast2 energy calibration (I think you already have this)
- energy smearing

The e/gamma scale factors are described here. From here you'd use the trigger, reconstruction and identification SFs (for tight++ where applicable). They are different for fullsim and AF2 so you need to specify the correct input:
https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/EfficiencyMeasurements#Electron_efficiencies_2011_Morio

The trigger SF is actually a bit more complicated to do correctly, since there are two electrons that could pass the trigger. This is discussed on the egamma twiki in the trigger section. What we do is described in the appendix of the backup note (currently A.2.2, "trigger efficiency calculation"):
https://svnweb.cern.ch/trac/atlasusr/browser/olivito/latex/SSInclusive/InternalNote/SS_sum11_internal.pdf

I have an implementation of the event-level trigger SF here:
https://svnweb.cern.ch/trac/penn/browser/olivito/SFrameDev/EgammaTools/src/EgammaSFTool.cxx#L29
I would put the electron trigger SF low on your list of things to do. The efficiency is high and the uncertainty on it will have little impact.

In addition to the egamma scale factors there are additional ones for our isolation cuts etc. These I derived and are on the analysis twiki, with separate values for fullsim and AF2 MC:
https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/InclusiveSSDileptons#Scale_Factors

The energy-related corrections are points 2-4 here:
https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/EnergyScaleResolutionRecommendations#2012_Moriond_Recommendations_AN1


You should have the following systematics for electrons:

- reconstruction, ID, trigger eff: these all come from the egammaSFclass as described on the efficiency twiki. They're the second entry in the pair returned by the tool.

- additional cuts eff: this is a flat 1% (per electron)

- energy scale, energy resolution: these are described on energy correction twiki.

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Topic revision: r1 - 2013-03-27 - KenjiHamano
 
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