Physics Objects in CMS Run 3

TL;DR

CMS Run 3 at $\sqrt{s}=13.6\u007f$ TeV tackles high pileup and large data volumes with pileup-resistant reconstruction. The paper reviews lepton, photon, jet, and MET reconstruction, highlighting the shift to PUPPI-based pileup mitigation and transformer-based tagging (ParticleNet, UParT) alongside ML-based PF (MLPF) for fast, accurate reconstruction. It documents calibration and efficiency strategies, tag-and-probe methods, and advanced MC modeling (Powheg-hvq + Pythia8 CP5, MiNNLO) that improve data-model agreement. The results indicate substantial gains in object resolution, background rejection, and $p_T^{miss}$ performance, positioning CMS for precision top-quark physics in Run 3.

Abstract

In these proceedings we review the physics objects used by the CMS experiment during LHC Run 3 at 13.6 TeV, including charged leptons, photons, jets, and missing transverse momentum. Their performance and calibration is critical for physics analysis. In particular, the algorithms need to be resilient against the high pileup conditions in Run 3 collisions. Furthermore, transformer-based algorithms are deployed for the identification of heavy-flavor jets and boosted resonances.