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# Introduction

This page describes the software and steps used in the analysis of "Single-diffractive W production", within the Forward PAG. For the physics description look here.

## Versions & Tags

The following tags are currently used for the analysis, on top of CMSSW_2_2_X:
   cvs co -r V03-03-00      DiffractiveForwardAnalysis/CMS.SingleDiffractiveWAnalysis
cvs co -r V00-00-01      DataFormats/CMS.CastorReco
cvs co -r V00-01-00      FastSimulation/ForwardDetectors
cvs co -r V00-01-00      RecoLocalCalo/Castor
cvs co -r V01-00-01      SimDataFormats/GeneratorProducts
scramv1 b


# Analysis chain

The analysis is made as modular as possible. It'll generally consist of two steps: a first sample reduction where most of the processing of new variables and collections will be made, saving only events satisfying a given selection and all the relevant information in EDM format. A second step will consist in analyzing these reduced (skimmed) samples and producing the final histograms and plain n-tuples for further inspection & plotting.

An example configuration file can be found here. The main sequences are defined in DiffractiveForwardAnalysis/SingleDiffractiveWAnalysis/python/analysisSequences_cff.py, which imports and defines the event selection sequence, as well as a simple analyzer to be run before and after the selection. Also imported is a edmDumpSequence, which defines a number of extra collections and variables produced. The paths and sequences defined in analysisSequences_cff are:

wmunuAnalysis = cms.Path(wmunuAnalyzer)
wmunuAfterFilter = cms.Path(wmunuSelFilter*wmunuAnalyzerAfterFilter)

wmunuSelectionSequence = cms.Sequence(wmunuSelFilter)
edmDumpSequence = cms.Sequence(wmunuSelFilter*genParticlesCalo*edmDumpAllNoPileUp)


plus optionally a number of analyzers for different pile-up conditions.

## Event selection

The events are selected using the WMuNuSelector, which can be obtained from the ElectroWeakAnalysis/WMuNu package.

### wmunuSelFilter

Description: Defines the filter used the event selection.

Imported/defined at: analysisSequences_cff

## Tracks selection

Inside DiffractiveForwardAnalysis/SingleDiffractiveWAnalysis/python/edmDump_cff.py, a few modules are defined to select and write in the event a subset of tracks of interest. The saved products are:

### selectGoodTracks

Description: Selects tracks according to quality criteria.

Imported/defined at: edmDump_cff

### selectTracksAssociatedToPV

Description: Select tracks associated to primary vertex (defaults modified in edmDump_cff).

Imported/defined at: edmDump_cff

### selectTracksAwayFromPV

Description: Select tracks away from (not associated to) primary vertex (defaults modified in edmDump_cff).

Imported/defined at: edmDump_cff

## "EDM variables"

A number of extra variables are additionally saved back in the event with the aim of advancing some of the processing associated to the analysis as well allowing to discard some collections in an intermediary step. The saved products are:

### castorGen/castorGenNoThreshold

Description: Produces generator level information for the energy deposits and multiplicity of Castor sectors above threshold. Only geometrical acceptance is taken into account.

Imported/defined at: edmDump_cff

### castorTower

Description: Saves multiplicites and energy depositions for Castor towers, taken from Castor reconstruction.

Imported/defined at: edmDump_cff

### hfTower

Description: Saves multiplicities and energy deposition for HF towers.

Imported/defined at: edmDump_cff

### xiTower/xiTowerNoMET

Description: Computes $\xi$ using as input calot towers. Different thresholds are allowed as well as the possibility of including muons and MET.

Imported/defined at: edmDump_cff

### xiFromJets/xiFromJetsNoMET

Description: Computes $\xi$ using jets as input.

Imported/defined at: edmDump_cff

### trackMultiplicity/trackMultiplicityAssociatedToPV/trackMultiplicityAwayFromPV

Description: Saves the multicplicity of tracks for each input collection.

Imported/defined at: edmDump_cff

## Pile-up

### pileUpInfo

Description: Saves the number of simulated pile-up events per bunch crossing.

Imported/defined at: edmDump_cff

## EdmDumpAnalyzer

The final analysis step runs over all the previously produced variables to obtain the final observables which are either plotted or stored in ROOT TTree format.

### edmDumpAnalysis

Several copies of the same analyzer are run with different filters (see below), which are used to select events according to simulated information, perform some further selection, select control samples, etc. Some simple python tools to create the different sequences are used from DiffractiveForwardAnalysis/SingleDiffractiveWAnalysis/python/analysisTools.py.

The final result is a ROOT file (saved through the TFileService) with directory for each defined analyzer (control histograms from some filters are also present).

## Analysis filters

### singleInteractionFilter

Description: Selects events with zero pile-up added (simulated).

Imported/defined at: analyzeEdmDump_cfg

### singleVertexFilter

Description: Selects events with a single reconstructed vertex.

Imported/defined at: analyzeEdmDump_cfg

### singleInteractionTMVAFilter

Description: Selects events according to a multivariate analysis to identify single-interaction events.

Imported/defined at: analyzeEdmDump_cfg

# Analysis Modules

## Contact

Responsible: Main.Grzegorz.Brona
Last reviewed by: Never reviewed

Topic revision: r5 - 2012-01-02 - DavidDEnterria

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