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Central value weights

The cross section model in GENIE 2.10.4 (Second Analysis version) is known to have some deficiencies that require reweighting to fix. (See, e.g., tech note in Doc 15214) Applying the so-called 'Tufts' weights are straightforward:

CAFAna

In CAFAna, simply use kTuftsWeightCC from CAFAna/Vars/GenieWeights.h as the wei parameter to any Spectrum you create from the MC.

ART

In an ART module, to get the 'Tufts' weights, you would:

  • Add the ⁠⁠⁠⁠MCReweight⁠⁠⁠⁠ service to your fhicl:
    #include "MCReweight.fcl" 
    ...
    services:
    {
     ...
     MCReweight: @local::standard_mcreweight
    }
    
  • Instantiate an MCReweight service instance in your module:
    #include "art/Framework/Services/Registry/ServiceHandle.h" 
    #include "MCReweight/MCReweight.h" 
    ...
    class MyModule : public art::EDAnalyzer
    {
     ...
     private:
      ...
      art::ServiceHandle<rwgt::MCReweight> fReweight;
    };
    
  • Ask for the weight for an ⁠⁠⁠⁠MCNeutrino⁠⁠⁠⁠ (where ⁠⁠⁠⁠nu⁠⁠⁠⁠ in the following example is a ⁠⁠⁠⁠simb::MCNeutrino*⁠⁠⁠⁠ that you get from the ⁠⁠⁠⁠BackTracker⁠⁠⁠⁠ or elsewhere):
    double tuftswgt = fReweight->GetWeight(nu, rwgt::kTuftsCC);
    

    Use this to weight any histograms you create from the MC.