OpTHyLiC: an Optimised Tool for Hybrid Limits Computation

TL;DR

OpTHyLiC is a software tool that efficiently computes upper limits on Poisson process rates using a hybrid statistical method, accommodating multiple channels and uncertainties for both simple and complex experiments.

Contribution

It introduces a validated, flexible software tool that combines frequentist and Bayesian methods for limit setting in particle physics experiments.

Findings

Validated against existing tools and analytical calculations.

Handles multiple channels and systematic uncertainties.

Applicable to simple and multi-bin experiments.

Abstract

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.