Jul 17 – 24, 2024
Prague
Europe/Prague timezone

Automatic Differentiation in RooFit for fast and accurate likelihood fits

Jul 20, 2024, 2:47 PM
17m
Club A

Club A

Parallel session talk 14. Computing, AI and Data Handling Computing and Data handling

Speaker

Jonas Rembser (CERN)

Description

With the growing datasets of HEP experiments, statistical analysis becomes more computationally demanding, requiring improvements in existing statistical analysis software. One way forward is to use Automatic Differentiation (AD) in likelihood fitting, which is often done with RooFit (a toolkit that is part of ROOT.) As of recently, RooFit can generate the gradient code for a given likelihood function with Clad, a compiler-based AD tool. At the CHEP 2023 conference, we showed how using this analytical gradient significantly speeds up the minimization of simple likelihoods. This talk will present the current state of AD in RooFit. One highlight is that it now supports more complex models like template histogram stacks ("HistFactory"). It also uses a new version of Clad that contains several improvements tailored to the RooFit use case. This contribution will furthermore demo complete RooFit workflows that benefit from the improved performance with AD, such as ATLAS Higgs measurements.

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Primary authors

David Lange (Princeton University (US)) Jonas Rembser (CERN) Lorenzo Moneta (CERN) Mr Petro Zarytskyi Vaibhav Thakkar (Princeton University (US)) Vassil Vassilev (Princeton University (US))

Presentation materials