Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This paper evaluates the performance of the CMS detector in reconstructing and identifying photons in 8 TeV proton-proton collisions, focusing on energy resolution, conversion tracking, and identification efficiency.

Contribution

It provides a detailed assessment of photon reconstruction and identification techniques in CMS, including energy calibration and simulation modeling for Higgs to gamma gamma analysis.

Findings

Achieved about 1% energy resolution for certain photons

Compared photon identification efficiencies between data and simulation

Optimized photon energy reconstruction methods

Abstract

A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. The reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H to gamma gamma decays. Different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events.