A First Full Physics Benchmark for Highly Granular Calorimeter Surrogates

TL;DR

This paper evaluates generative models for highly granular calorimeter shower simulation within realistic collider detector environments, introducing benchmarks and comparing grid and point cloud approaches for improved speed and accuracy.

Contribution

It introduces DDML, a library for integrating generative calorimeter surrogates with realistic detector simulations, and provides the first comprehensive benchmarks for multi-particle and full-physics scenarios.

Findings

Point cloud models balance speed and accuracy well.

Models perform effectively on realistic detector simulations.

Benchmarking on tau decays demonstrates practical applicability.

Abstract

The physics programs of current and future collider experiments necessitate the development of surrogate simulators for calorimeter showers. While much progress has been made in the development of generative models for this task, they have typically been evaluated in simplified scenarios and for single particles. This is particularly true for the challenging task of highly granular calorimeter simulation. For the first time, this work studies the use of highly granular generative calorimeter surrogates in a realistic simulation application. We introduce DDML, a generic library which enables the combination of generative calorimeter surrogates with realistic detectors implemented using the DD4hep toolkit. We compare two different generative models - one operating on a regular grid representation, and the other using a less common point cloud approach. In order to disentangle methodological details from model performance, we provide comparisons to idealized simulators which directly sample representations of different resolutions from the full simulation ground-truth. We then systematically evaluate model performance on post-reconstruction benchmarks for electromagnetic shower simulation. Beginning with a typical single particle study, we introduce a first multi-particle benchmark based on di-photon separations, before studying a first full-physics benchmark based on hadronic decays of the tau lepton. Our results indicate that models operating on a point cloud can achieve a favorable balance between speed and accuracy for highly granular calorimeter simulation compared to those which operate on a regular grid representation.