02. Implementation of Systematic

Most of the implementation is being handled via config which is being passed to the covariance object. It contains information like the name of the parameter, prior value prior error and type of systematic.

There are three types of systematic within MaCh3 framework:

1. Splines
2. Normalisation
3. Function

Splines

Splines are being handled via a dedicated spline class. The most important thing is to ensure the correct name of the spline which will be loaded via input file.

- Systematic:
    DetID: 985
    Error: 0.06
    FlatPrior: false
    IsFixed: false
    Mode: []
    Names:
      FancyName: MaQE
      ParameterName: MAQE
    ParameterBounds:
    - 0.0
    - 9999
    ParameterGroup: Xsec
    ParameterValues:
      Generated: 1.21
      PreFitValue: 1.03
    SplineInformation:
      FDMode: [0]
      FDSplineName: MaCCQE
      InterpolationType: TSpline3
      NDSplineName: MAQEGraph
    StepScale:
      MCMC: 0.4
    Type: Spline

Normalisation

Implementation of these relies on KinematicCuts. Based on which event is affected by a given norm param or not.

- Systematic:
    DetID: 985
    Error: 0.11
    FlatPrior: false
    IsFixed: false
    Mode: [ 0 ]
    Names:
      FancyName: Q2_norm_5
      ParameterName: Q2_norm_5
    ParameterBounds:
      - 0
      - 999.
    ParameterGroup: Xsec
    TargetNuclei: [12, 16]
    KinematicCuts:
      - TrueQ2:
        - 0.25
        - 0.5
    ParameterValues:
      Generated: 1.
      PreFitValue: 1.
    StepScale:
      MCMC: 0.2
    Type: Norm

Functional

These need to be implemented in experiment specific SamplePDF via CalcXsecWeightFunc.

- Systematic:
    DetID: 1
    Error: 6
    FlatPrior: false
    IsFixed: false
    Names:
      FancyName: EB_dial_C_nu
      ParameterName: EB_dial_C_nu
    ParameterBounds:
      - -10.
      - 15.
    ParameterGroup: Xsec
    ParameterValues:
      Generated: 0
      PreFitValue: 2.
    Correlations:
      - EB_dial_C_nubar: 0.778
      - EB_dial_O_nu: 0.870
      - EB_dial_O_nubar: 0.653
    StepScale:
      MCMC: 0.2
    Type: Functional