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May 8 – 12, 2023
Norfolk Waterside Marriott
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The LHCb ultra-fast simulation option, Lamarr: design and validation

May 8, 2023, 3:00 PM
Chesapeake Meeting Room (Norfolk Waterside Marriott)

Chesapeake Meeting Room

Norfolk Waterside Marriott

235 East Main Street, Norfolk, VA, 23510
Oral Track 3 - Offline Computing Track 3+9 Crossover


Barbetti, Matteo (INFN Firenze)


Detailed detector simulation is the major consumer of CPU resources at LHCb, having used more than 80% of the total computing budget during Run 2 of the Large Hadron Collider at CERN. As data is collected by the upgraded LHCb detector during Run 3 of the LHC, larger requests for simulated data samples are necessary, and will far exceed the pledged resources of the experiment, even with existing fast simulation options. An evolution of technologies and techniques to produce simulated samples is mandatory to meet the upcoming needs of analysis to interpret signal versus background and measure efficiencies. In this context, we propose Lamarr, a Gaudi-based framework designed to offer to LHCb the fastest solution for simulations.
Lamarr consists of a pipeline of modules parametrizing both the detector response and the reconstruction algorithms of the LHCb experiment. Most of the parameterizations are made of Deep Generative Models and Gradient Boosted Decision Trees trained on simulated samples or alternatively, where possible, on real data. Embedding Lamarr in the general LHCb Gauss Simulation framework allows combining its execution with any of the available generators in a seamless way.
Lamarr has been validated by comparing key reconstructed quantities with Detailed Simulation. Good agreement of the simulated distributions is obtained with two-order-of-magnitude speed-up of the simulation phase.

Primary authors

Barbetti, Matteo (INFN Firenze) Corti, Gloria (CERN) Davis, A. (University of Manchester) Derkach, D. (High School of Economics (HSE) University) Kazeev, N. (High School of Economics (HSE) University) Maevskiy, A. (High School of Economics (HSE) University) Mokhnenko, S. (High School of Economics (HSE) University) Siddi, B. G. (University of Ferrara) Xu, Z. (Université Clermont Auvergne) Anderlini, Lucio (INFN Firenze) Martinelli, Maurizio (INFN Milano-Bicocca) Capelli, Simone (INFN Milano-Bicocca)

Presentation materials