OpTHyLiC: An Optimised Tool for Hybrid Limits Computation

A software tool, computing observed and expected upper limits on Poissonian process rates using a hybrid frequentist-Bayesian CLs method, is presented. This tool can be used for simple counting experiments where only signal, background and observed yields are provided or for multi-bin experiments where binned distributions of discriminating variables are provided. It allows the combination of several channels and takes into account statistical and systematic uncertainties, as well as correlations of systematic uncertainties between channels. It has been validated against other software tools and analytical calculations, for several realistic cases. Program Title:OpTHyLiC Program Files doi:http://dx.doi.org/10.17632/2jv8ytrhcg.1 Licensing provisions: GPLv3 Programming language: C++ Supplementary material:http://opthylic.in2p3.fr Nature of problem: computation of limits on Poissonian process rates in presence of background when no signal is observed, taking correctly into account statistical and systematic uncertainties, in particular correlations of systematic uncertainties between samples and channels. Solution method: a C++ library to be used together with the ROOT C++ package, using a hybrid frequentist-Bayesian CLs method; the optimisation of the program typically reduces the limit computation time down to less than a few minutes in realistic cases. Additional comments including Restrictions and Unusual features: the ROOT software is necessary.