Normalizing Flows for Physics Data Analyses

¹ Jožef Stefan Institute, Jamova 39, Ljubljana, 1000, Slovenia
² Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, Ljubljana, 1000, Slovenia

^* e-mail: jan.gavranovic@ijs.si
^** e-mail: borut.kersevan@ijs.si

Published online: 7 October 2025

Abstract

Monte Carlo simulations are a crucial component when analysing the Standard Model and New physics processes at the Large Hadron Collider. The goal of this work is to explore the performance of generative models for complementing the statistics of classical MC simulations in the final stage of data analysis by generating additional synthetic data that follows the same kinematic distributions for a limited set of analysis-specific observables to a high precision. Machine learning generative models were adapted for this task and their performance was systematically evaluated using a well-known benchmark sample containing the Higgs boson production beyond the Standard Model and the corresponding irreducible background. The best performing model was chosen for further evaluation with a set of statistical procedures and a simplified physics analysis. By implementing and performing a series of statistical tests and evaluations we show that a machine-learning-based generative procedure can can be used to generate synthetic data that matches the original samples closely enough and that it can therefore be incorporated in the final stage of a physics analysis with some given systematic uncertainty.