Photons (and Electrons) Scale and Smearing

After the standard ECAL calibration procedure has been applied, the remaining differences between the electron and photon energy scales and the resolution in the data and simulation need to be corrected for. A multistep procedure is implemented to correct this residual energy Scale difference. An additional Smearing is also applied to the photon energy in simulation such that the energy resolution in simulation is comparable to that in data.

Photon case

The Scale and Smearing corrections adjust the transverse momentum of each photon (and electron, see Electron case). All the corrections are pT-dependent and are derived using the IJazZ method (2602.17300).

Three sets of corrections are available for Run 2 and Run 3:

• Scale_EGM and Smearing_EGM: These corrections are pulled from the central EGM POG repository. The Zmmg photon energy scale corrections are not yet implemented, therefore we do not recommend using them for the moment.

• Scale and Smearing: These corrections include both the Zee scale and Zmmg scales corrections. The Zmmg scale corrections are needed for photons as a large non-closure is observed when applying the Zee only scales to photons (link). Moreover, they use a new smearing function (double Gaussian instead of a single Gaussian) to address the observed low-energy tail issue on Zee (link).

• Scale_Zee and Smearing: These corrections are recommended to derive SFs or perform validation on Zee events where the electrons are reconstructed as photons.

Scale corrections are applied only to data while Smearing corrections are applied to MC. The Scale_Zee, Scale_Zmmg, and Smearing systematics are applied to MC. And both Scale_Zee, Scale_Zmmg systematics can be splitted for EB and EE.

Correlations between the systematics and the years:

• Only the Scale_Zmmg sytematics must be correlated between 2022 and 2023 (or Run 2), as the corrections are derived from a combined fit to both years. The other systematics can be considered uncorrelated between the years and between EB and EE.

An example of applying Scale and Smearing while considering their systematics is provided here. The configuration json is as follows:

{
    "samplejson": "samples.json",
    "workflow": "base",
    "metaconditions": "Era2022_v1",
    "taggers": [],
    "year": {
        "GluGluHtoGG": [
            "2023preBPix"
        ],
        "EGammaC": [
            "2023preBPix"
        ]
    },
    "corrections": {
        "GluGluHtoGG": [
            "Pileup", "Smearing"
        ],
        "EGammaC": [
            "Scale"
        ]
    },
    "systematics": {
        "GluGluHtoGG": [
            "Scale_Zee", "Scale_Zmmg", "Smearing"
        ],
        "EGammaC": [
        ]
    }
}

Alternativly, the Scale sytematics can be splitted for EB and EE.

{
    "samplejson": "samples_nanov13.json",
    "workflow": "base",
    "metaconditions": "Era2022_v1",
    "taggers": [],
    "year": {
        "GluGluHtoGG": [
            "2023preBPix"
        ],
        "EGammaC": [
            "2023preBPix"
        ]
    },
    "corrections": {
        "GluGluHtoGG": [
            "Pileup", "Smearing"
        ],
        "EGammaC": [
            "Scale"
        ]
    },
    "systematics": {
        "GluGluHtoGG": [
            "ScaleEB_Zee", "ScaleEE_Zee", "ScaleEB_Zmmg", "ScaleEE_Zmmg", "Smearing"
        ],
        "EGammaC": [
            ""
        ]
    }
}

And for SFs derivation or validation on Zee events, the configuration json can be as follows:

{
    "samplejson": "samples.json",
    "workflow": "zee",
    "metaconditions": "Era2022_v1",
    "taggers": [],
    "year": {
        "DYto2L": [
            "2023preBPix"
        ],
        "EGammaC": [
            "2023preBPix"
        ]
    },
    "corrections": {
        "DYto2L": [
            "Pileup", "Smearing"
        ],
        "EGammaC": [
            "Scale_Zee"
        ]
    },
    "systematics": {
        "DYto2L": [
            "Scale_Zee", "Smearing"
        ],
        "EGammaC": [
        ]
    }
}

Electron case

The central EGM scale and smearing corrections are also available for electrons:

• Electron_Scale_EGM and Electron_Smearing_EGM

Run2UL

• NanoAODv9: The scale and smearing corrections for Run 2 are already applied in NanoAODv9 samples using an old method but NanoAODv9 samples are no longer supported in HDNA.

• NanoAODv15: The scale and smearing corrections are not applied anymore in NanoAODv15 samples and should be applied as for Run 3. The only difference is that the smearing function used for Run 2 is a single Gaussian as the double Gaussian smearing function was not yet needed for Run 2.

Muons Scale and Smearing

The MuonScaRe correct the transverse-momentum of each muons. Following MUO POG recommendations.

The MuonScaRe should be applied on both data and MC. For data it applies Scale correction and for MC it applies both Scale and Smearing corrections. The MuonScaRe systematics are applied on MC.