# Particle-flow reconstruction and global event description with the CMS detector

## TL;DR

This paper presents a particle-flow reconstruction algorithm for the CMS detector, enabling detailed event descriptions that improve the accuracy of particle identification, jet reconstruction, and pileup mitigation in high-energy proton-proton collisions.

## Contribution

The development and implementation of a comprehensive particle-flow algorithm tailored for CMS, enhancing event reconstruction and analysis capabilities at the LHC.

## Key findings

- Excellent agreement between data and simulation at 8 TeV
- Improved jet and tau decay reconstruction performance
- Effective pileup mitigation up to 20 interactions

## Abstract

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions.