Experiments using machine learning to approximate likelihood ratios for mixture models

K. Cranmer, J. Pavez, G. Louppe, W. K. Brooks

    Research output: Contribution to journalConference article

    Abstract

    Likelihood ratio tests are a key tool in many fields of science. In order to evaluate the likelihood ratio the likelihood function is needed. However, it is common in fields such as High Energy Physics to have complex simulations that describe the distribution while not having a description of the likelihood that can be directly evaluated. In this setting it is impossible or computationally expensive to evaluate the likelihood. It is, however, possible to construct an equivalent version of the likelihood ratio that can be evaluated by using discriminative classifiers. We show how this can be used to approximate the likelihood ratio when the underlying distribution is a weighted sum of probability distributions (e.g. signal plus background model). We demonstrate how the results can be considerably improved by decomposing the ratio and use a set of classifiers in a pairwise manner on the components of the mixture model and how this can be used to estimate the unknown coefficients of the model, such as the signal contribution.

    Original languageEnglish (US)
    Article number012034
    JournalJournal of Physics: Conference Series
    Volume762
    Issue number1
    DOIs
    StatePublished - Nov 21 2016
    Event17th International Workshop on Advanced Computing and Analysis Techniques in Physics Research, ACAT 2016 - Valparaiso, Chile
    Duration: Jan 18 2016Jan 22 2016

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

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