End-to-end event reconstruction for precision physics at future colliders

TL;DR

This paper introduces an end-to-end global event reconstruction method for future collider experiments that significantly improves particle identification, energy resolution, and reduces fake rates, aiding detector design and physics measurements.

Contribution

The authors present a novel, detector-agnostic reconstruction framework combining geometric algebra transformer networks with object condensation clustering, outperforming existing algorithms.

Findings

Outperforms state-of-the-art algorithms by 10-20% in efficiency

Reduces fake-particle rates for charged hadrons by up to two orders of magnitude

Improves energy and invariant mass resolution by 22%

Abstract

Future collider experiments require unprecedented precision in measurements of Higgs, electroweak, and flavour observables, placing stringent demands on event reconstruction. The achievable precision on Higgs couplings scales directly with the resolution on visible final state particles and their invariant masses. Current particle flow algorithms rely on detector specific clustering, limiting flexibility during detector design. Here we present an end-to-end global event reconstruction approach that maps charged particle tracks and calorimeter and muon hits directly to particle level objects. The method combines geometric algebra transformer networks with object condensation based clustering, followed by dedicated networks for particle identification and energy regression. Our approach is benchmarked on fully simulated electron positron collisions at FCC-ee using the CLD detector concept. It outperforms the state-of-the-art rule-based algorithm by 10--20\% in relative reconstruction efficiency, achieves up to two orders of magnitude reduction in fake-particle rates for charged hadrons, and improves visible energy and invariant mass resolution by 22\%. By decoupling reconstruction performance from detector-specific tuning, this framework enables rapid iteration during the detector design phase of future collider experiments.