CMS 2013 Public Photon Performance Results

Table of contents:

Cut Based Photon Identification

Efficiencies and Data To Simulation Scaling Factors

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Left: the efficiency in Monte Carlo (MC) simulation of the Tight (blue), Medium (red), and Loose (black) working points of the cut-based Photon ID as a function of photon transverse energy in the ECAL barrel. The signal Monte Carlo simulation is PYTHIA γ + Jets. Right: the efficiency in Monte Carlo simulation of cut-based Photon ID as a function of photon transverse energy in the ECAL endcaps.

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The efficiency in simulation of the Tight (blue), Medium (red), and Loose (black) working points of the cut-based Photon ID as a function of photon pseudorapidity. The signal Monte Carlo simulation is PYTHIA γ + Jets Monte Carlo.

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Left: the efficiency in simulation of the Tight (blue), Medium (red), and Loose (black) working points of the cut-based Photon ID as a function of primary vertex multiplicity in the ECAL barrel. The signal simulation is PYTHIA γ + Jets Monte Carlo. The pileup dependence is mainly due to soft photons. Right: the efficiency in simulation of Cut Based Photon ID as a function of primary vertex multiplicity in the ECAL endcaps.

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Left: the receiver operator characteristic (ROC) curve for Tight (blue), Medium (red), and Loose (black) working points of the cut-based Photon ID in the ECAL barrel. The efficiencies for signal are measured using Wγ Monte Carlo simulation and the background is from W+Jets simulation. Both simulation samples are obtained using the MadGraph simulation program interfaced to PYTHIA. Right: the ROC curve for the working points of the cut-based Photon ID in the ECAL endcaps.

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The scale factor for the full photon selection efficiency in the ECAL barrel. The total scale factor is determined by the product of the scale factor calculated using the tag and probe technique and the scale factor of the electron veto. The electron veto scale factor is calculated in data and simulation by counting the number of passing and failing photons from Z→μμγ process, which is ~99.6% pure source of photons. Uncertainties are both statistical and systematic.

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The scale factor for the full photon selection efficiency in the ECAL endcaps. The total scale factor is determined by the product of the scale factor calculated using the tag and probe technique and the scale factor of the electron veto. The electron veto scale factor is calculated in data and simulation by counting the number of passing and failing photons from Z→μμγ process, which is ~99.6% pure source of photons. Uncertainties are both statistical and systematic.

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Left: the invariant mass distribution of reconstructed electron pairs matched to reconstructed photons that pass the Medium cut-based Photon ID working point without electron veto. The signal shape is derived from a Monte Carlo simulation line shape that is convolved with a gaussian. Right: the equivalent distribution where one electron candidate does not pass the Medium working point.

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Left: the invariant mass distribution of reconstructed electron pairs matched to reconstructed photons that pass the Medium cut-based Photon ID working point without electron veto. The signal shape is derived from a Monte Carlo simulation line shape that is convolved with a gaussian. Right: the equivalent distribution where one electron candidate does not pass the Medium working point.

Data To Simulation Comparison of ID Variables

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Left: event yields passing and failing the electron veto of the cut-based Photon ID Medium working point, in the barrel ECAL for data and Monte Carlo simulation of Z→μμγ process. The hatched band is the uncertainty on the simulation prediction. The residual data to Monte Carlo disagreement is under study and likely due to improper simulation of the detector materials. Right: as in the left plot, but for the ECAL endcaps.

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Left: the distribution of the ratio of hadronic energy behind the super-cluster to the photon super-cluster energy in the barrel ECAL for data and Monte Carlo simulation of the Z→μμγ process. The hatched band is the uncertainty on the simulation prediction. Right: as in the left plot, but for the ECAL endcaps.

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Left: the distribution of the covariance in the η of the photon super-cluster, in the barrel ECAL for data and Monte Carlo simulation of the Z→μμγ process. The hatched band is the uncertainty on the simulation prediction. Right: as in the left plot, but for the ECAL endcaps.

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Left: the distribution of selected photons’ charged hadron isolation corrected for the presence of additional proton-proton collisions, in the barrel ECAL for data and Monte Carlo simulation of the Z→μμγ process. The hatched band is the uncertainty on the simulation prediction. Right: as in the left plot, but for the ECAL endcaps.

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Left: the distribution of the selection photons’ neutral hadron isolation corrected for the presence of additional proton-proton collisions, in the barrel ECAL for data and simulation of the Z→μμγ process. The hatched band is the uncertainty on the simulation prediction. Right: as in the left plot, but for the ECAL endcaps.

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Left: the distribution of the selected photons’ neutral electromagnetic isolation corrected for the presence of additional proton-proton collisions, in the barrel ECAL for data and Monte Carlo simulation of the Z→μμγ process. The hatched band is the uncertainty on the simulation prediction. Right: as in the left plot, but for the ECAL endcaps.

Multivariate (MVA) Photon Identification for Higgs to Two Photons (Supplementary to HIG-13-001)

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Left: the transverse momentum distribution of pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process in barrel. Right: as in the left plot, but for the ECAL endcaps.

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The pre-selected photon super-cluster (SC) pseudorapidity with respect to the center of the CMS detector for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process.

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Left: the super-cluster (SC) η width for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for ECAL barrel. The shape of the Monte Carlo is corrected by a linear transformation derived from Z boson decays to electrons. Right: as in the left plot, but for the ECAL endcaps.

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Left: the super-cluster (SC) φ width for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for ECAL barrel. The shape of the Monte Carlo is corrected by a linear transformation derived from Z boson decays to electrons. Right: as in the left plot, but for the ECAL endcaps.

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Left: the ECAL-crystal-based shower covariance in the η direction for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for ECAL barrel. The shape of the Monte Carlo is corrected by a linear transformation derived from Z boson decays to electrons. Right: as in the left plot, but for the ECAL endcaps.

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Left: the off-diagonal term of the ECAL-crystal-based shower covariance in η and φ for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for ECAL barrel. Right: as in the left plot, but for the ECAL endcap.

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The width of pre-selected photons measured using the pre-shower detector situated in front of the ECAL endcap in data and Monte Carlo simulation of the Z→μμγ process.

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Left: the ratio of energy in a 3x3 crystal square about the highest-energy crystal to the energy of the super-cluster (SC) for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for ECAL barrel. The shape of the Monte Carlo is corrected by a linear transformation derived from Z boson decays to electrons. Right: as in the left plot, but for the ECAL endcaps.

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Left: zoom to the peak of the ratio of energy in a 3x3 crystal square about the highest-energy crystal to the energy of the super-cluster (SC) for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for ECAL barrel. The shape of the Monte Carlo is corrected by a linear transformation derived from Z boson decays to electrons. Right: as in the left plot, but for the ECAL endcaps.

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Left: the ratio of energy in the 2x2 crystal square with the highest energy sum to the total energy in 5x5 crystals centered on the highest energy crystal for pre-selected photons in Monte Carlo simulation of the Z→μμγ process compared to data for ECAL barrel. The shape of the Monte Carlo is corrected by a linear transformation derived from Z boson decays to electrons. Right: as in the left plot, but for the ECAL endcaps.

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Left: the average energy density in the CMS detector, which is an estimate of vertex multiplicity, in events with pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for the ECAL barrel. Right: as in the left plot, but for the ECAL endcaps.

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Left: the charged hadron isolation sum requiring charged hadrons from the collision vertex that yields the largest charged hadron isolation sum for pre-selected photons in Monte Carlo simulation of the Z→μμγ process compared to data for the ECAL barrel. Right: as in the left plot, but for the ECAL endcap.

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Left: the charged hadron isolation sum at the nominal primary vertex for pre-selected photons in data and Monte Carlo simulation of the Z→μμγ process for the ECAL barrel. Right: as in the left plot, but for the ECAL endcaps.

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Left: the electromagnetic isolation sum for pre-selected photons in Monte Carlo simulation of the Z→μμγ process compared to data for the ECAL barrel. Right: as in the left plot, but for the ECAL endcap.

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Left: the per-event percent photon energy resolution estimate for pre-selected photons in Monte Carlo simulation of the Z→μμγ process compared to data for the ECAL barrel. Right: as in the left plot, but for the ECAL endcaps.

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Left: the output of the photon ID MVA using the inputs shown previously for Monte Carlo simulation of the Z→μμγ process compared to data for the ECAL barrel. Residual differences between data and Monte Carlo are corrected within the H→γγ analysis using a linear scale transformation. Right: as in the left plot, but for the ECAL endcaps.