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Short description.

Physics Motivation: this process is directly related to contact interaction e-e-Z-H-H, left and right asymmetry (via cross section measurements for polarized beams) can provide a very strong constraints. Current best precision from SLD is still very limited. 

Search Channel: e+e- → gamma Z, Z→ll/qq, Ecm=500 GeV.

Detector Benchmark: thanks to the known central value of gamma energy / Z invariant mass; calibrate jet energy scale, calibrate lepton momentum scale, calibrate photon energy scale (though only at one energy). Isolated photon/lepton reconstruction/tagging efficiencies, jet/photon energy resolution.

Main observables.

final observable: A_LR for cross section of e+e- → gamma Z.

intermediate observables: lepton/photon reconstruction efficiencies, momentum/energy resolution/scale, JER/JES.

Analysis note and plots for IDR.

Photon energy scale calibration.

The method of the calibration and detailed description of the plots are shown below.

Link to the Analysis note: ILD notes

Plots for IDR.

<Plot 1.> The comparison of (E-EMC)/EMCamong PFO, calibrated PFO, and Ang. Method


*Mean value of (E-EMC)/EMC in PFO has large dependence on |cosθγ|. Considering this dependence, calibration is performed by each value range of |cosθγ|.

**Large ILD model samples are included in this plot.

<Plot 2.> Sigma of (E-EMC)/EMCdependence on |cosθγ|


*ECAL has two longitudinal sections with different sampling thickness. Large fluctuation of PFO might be caused by the effects of the change in relative fraction of the shower sampled in the two sections.

<Plot 3.> Sigma of (E-EMC)/EMCdependence on φγ


*Large fluctuation of PFO is due to the structure of ECal which has 8 gaps.

<Plot 4.> Sigma of (E-EMC)/EMCdependence on Eγ


<Plot 5.> Mean of (E-EMC)/EMCdependence on Eγ


*The Eγvalue of the plotted point of “Calibrated PFO” in this plot is artificially -2 GeV shifted.

**Large ILD model samples are included in this plot.

<Plot 6.> EγScale Uncertainty


Link to GitHub:


Takahiro Mizuno (KEK) + Junping Tian (University of Tokyo)

Reviewed by Matthew Wing


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