Signal region combination with full and simplified likelihoods in MADANALYSIS 5

The statistical combination of disjoint signal regions in reinterpretation studies uses more of the data of an analysis and gives more robust results than the single signal region approach. We present the implementation and usage of signal region combination in MADANALYSIS 5 through two methods: an interface to the PYHF package making use of statistical models in JSON-serialised format provided by the ATLAS collaboration, and a simplified likelihood calculation making use of covariance matrices provided by the CMS collaboration. The gain in physics reach is demonstrated 1.) by comparison with official mass limits for 4 ATLAS and 5 CMS analyses from the Public Analysis Database of MADANALYSIS 5 for which signal region combination is currently available, and 2.) by a case study for an MSSM scenario in which both stops and sbottoms can be produced and have a variety of decays into charginos and neutralinos.

Automated summary

In reinterpretation studies, the statistical combination of disjoint signal regions utilizes more data and yields more reliable results compared to the single signal region approach. This paper presents the implementation and usage of signal region combination in MADANALYSIS 5 through two methods: an interface to the PYHF package using statistical models in JSON-serialized format provided by the ATLAS collaboration, and a simplified likelihood calculation utilizing covariance matrices provided by the CMS collaboration. The improvement in physics reach is demonstrated by comparing it with the official mass limits of ATLAS and CMS analyses in the Public Analysis Database of MADANALYSIS 5 and by a case study of an MSSM scenario involving stops, sbottoms, charginos, and neutralinos.