Updates needed for morphing

[ajgilbert]

@rcl11 @ffrensch

Just my thoughts on building the model in the text2workspace step instead of pre-building in the datacard creation. This is the step we need to get to to start doing serious combinations.

• Datacard creation step should just build the RooMorphingPdfs, leaving the mass of each Higgs as a floating parameter.
• The text2workspace step would then, with an appropriate physics model, connect the mass parameters to the appropriate variables (e.g. mA stays as a floating variable, mh and mH defined as functions of mA and tanb.
• The big problem we hit here is being able to convert the mass parameter in the RooMorphingPdfs from the initial floating variable to a function.
  • One way would be to define the mass parameter as a function, e.g. mA_func, mH_func, that at the datacard creation step will just equal the value of some floating var, e.g. mA_initial, mH_initial (suffixes to avoid name collisions later with the final vars).
  • Then at the text2workspace step we put the actual functions in the workspace first, then rely on the RecycleConflictNodes() option in the pdf import to get these nodes hooked up to the actual mh and mH functions. Problem with this is that text2workspace doesn't use the RecycleConflictNodes() option when importing pdfs, which in general is a good idea but not useful for us. Maybe we should add a command line option that will do the import with RecycleConflictNodes() instead.

will update this issue as we decide what to do or other questions come up.