I developed a model for an on/off problem, where my likelihood is the product of two Poisson functions, the first depends on the measured number of events “n” in the signal region, with mean value S+B+B’, and the second is a Poisson function that depends on the measured number of events “m” in the control region, with mean value “tau * B”. “tau” and “B’” are two constant parameters, with no uncertainty. B is a nuisance parameter.
If I understood correctly, the CLb value should not depend on the POI (here, S). However, If I try to calculate an upper limit, both with the AsympoticCalculator and with the FrequentistCalculator, I get a dependence on “S” for small value of this. I attach two plots to show this, obtained, respectively, from the AsymptoticCalculator and from the FrequentistCalculator.
I also attach the workspace, and the code I use for hypo inversion.
I am using ROOT version 6.20/04 on Centos7.
Thanks in advance,