Composed PDFs build on top of others and provide sums, products and more.

zfit.pdf.ProductPDF(pdfs[, obs, extended, ...])	Product of multiple PDFs in the same or different variables.
zfit.pdf.SumPDF(pdfs[, fracs, obs, ...])	Create the sum of the pdfs with fracs as coefficients or the yields, if extended pdfs are given.
zfit.pdf.FFTConvPDFV1(func, kernel[, n, ...])	EXPERIMENTAL Numerical Convolution pdf of func convoluted with kernel using FFT.
zfit.pdf.ConditionalPDFV1(pdf, cond, *[, ...])	EXPERIMENTAL! Implementation of a Conditional PDF, rather slow and for research purpose.
zfit.pdf.TruncatedPDF(*args[, obs])	Truncated PDF in one or multiple ranges.