Electron and Photon Physics Object Offline Guide


Data Formats

Information on the egamma physics object data format can be found in:

The full list of products can be found in the following pages:

DataFormats types for egamma physics objects are defined in Dataformats/EgammaCandidates.

Algorithms and Software Architecture

Default sequences used for Electron/Photon Reconstruction

Egamma Algorithms

Standard Electron/Photon physics objects

The standard collections of electrons and photons are intended to be efficient for electrons with pt>5GeV and prompt photons with pt>10GeV. The photons are based on ECAL superclusters. Electrons are reconstructed by matching ECAL superclusters to track seeds found in, or close to, the pixel detectors. On these seeds tracks are reconstructed using the GSF tracking algorithm. To this collection of electrons are added the electrons found by the track based algorithm developed in the PFlow group. The majority of electrons in the merged collection are found by both algorithms.

The preselection of both collections, photons and electrons, is rather loose and both collections are dominated by fakes (where "fake" is taken to include non-prompt photons e.g. from pizeros, and electrons from conversions). Also: most (in 31X: all [to be verified]) superclusters of ECAL supercluster seeded electrons with pt>10 appear also in the photon collection.

A more detailed description of electron objects is available here.

Further electron and photon identification, beyond preselection, generally needs to be specific to use cases. This is because a) the relatively large fake rate and numerous imperfect identification variables gives much elasticity in tradeoffs between efficiency and purity, and b) different cuts are needed for different pt ranges. The most developed identification for electrons is for the 20<pt<70GeV regime appropriate for electrons from W and Z decay.

Package Architecture

CMSSW Subsystem: RecoEgamma

Packages within RecoEgamma:

Validation and Release Notes

Usage and How-Tos

Usage of the egamma software is described in the Tutorials below.

Patches/Bugfixes to CMSSW versions < 16


Review status

Reviewer/Editor and Date (copy from screen) Comments
KatiLassilaPerini - 22 Feb 2007 created template page
DavidFutyan - 04 Jul 2008 last content editor
NancyMarinelli - 30 Jul 2008 last content editor
VanlaerPascal - 04 Jul 2008 last content editor

Last reviewed by: MatteoSani - 20 Jul 2009

%RESPONSIBLES% PaoloMeridiani, MarcoPieri

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf bugreport.pdf r1 manage 169.8 K 2007-08-01 - 16:06 UnknownUser bug report 131
Unknown file formatcfg rerecoEgamma131.cfg r1 manage 0.7 K 2007-07-25 - 14:24 UnknownUser config file to re-reconstruct electrons with 131 and Claude's patch
Unknown file formatcfg runEgammaObjectsElectrons.cfg r1 manage 0.6 K 2007-07-25 - 13:43 UnknownUser config file to plot efficiency for pixelMatchGsfElectrons
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Topic revision: r55 - 2013-10-17 - AndreyPozdnyakov

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