RooFit product category

I have two RooCategories:

[code]prodFlav = RooCategory(“prodFlav”,“production flavour”)

catMistag1 = RooCategory(“catMistag1”,“whether tagger 1 tagged wrong”)

which I use for the generation of toy data.
For fitting, I’d like to use the actual taggers decision. So far this is

Tag1Form = RooFormulaVar("Tag1","prodFlav*catMistag1",RooArgList(prodFlav,catMistag1))
Tag1 = local_data.addColumn(Tag1Form)

which almost does the job, except that Tag1 is now not a RooCategory (which for various RooFit classes I’m using require). I am aware that there is the RooMultiCategory (which I apply in another place successfully) but here I’m not interested in distinguishing {B0bar;right} from {B0;wrong} - instead I am very interested in having the the numeric values +1 and -1.

Is there something like this ProductCategory in place? Or anything else to build categories from categories with formulas?


I think I see a workaround using first a RooMultiCategory to combine the categories I want to multiply and then a RooMappedCategory.