root  .L <macro_name.C> root  <macro_name()>
For the former version the result is as expected:
Poisson_posterior_for_5_nobs_and_0_b_618.pdf (15.8 KB)
While for the more recent version the RooProdPdf “jefPrior_posterior” seems to be zero everywhere:
Poisson_posterior_for_5_nobs_and_0_b_622.pdf (15.3 KB)
This difference in behaviour seems independent of the values of the parameters.
Any help will be greatly appreciated.