I want to describe my mass distribution in TH1 histogram with help interference two Breit-Wigner function: BW1 + Z * exp(i * phi) * BW2. In code I expect to see something this:
Hi,
You can create a TF1 or better a TF2 (a two dimensional function) using as input the real and imaginary part of a complex number or the module and the phase phi of the number.
Remember you can pass to a TF1 a string expression (a TFormula) as above or a C++ function. See ROOT: TF1 Class Reference