Dear all,

I’m not sure what I should put into the ForcePriorNuisanceAlt and ForcePriorNuisanceNull methods of the HybridCalculator class.

I want to measure the significance of a signal hypothesis over a null hypothesis with the ProfileLikelihoodTestStat and the HybridCalculator.

Here a simplified example of my problem.

I have an extended likelihood that consists of a signal pdf (with fixed shape) plus an exponential background.

So my likelihood is:

L = (N_s * S(m) + N_b * Expo (m| tau) ) * Gau(tau| tau_0, sigma_0)

N_s and N_b are the floating signal and bkg yields.

S(m) is fixed.

The exponential depends on tau wich is constrained with a Gaussian, with constant mean and sigma.

My null hypothesis is N_s = 0.

So, in the end, my p.o.i. is N_s, my noisance parameters are N_b and tau, and tau is a constrained parameter.

Thus, given my problem, what should I put into the ForcePriorNuisanceAlt(Null) methods?

Thank you very much in advance for your help,

Luca