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Short description:

Physics Motivation: A precision measurement of the quartic interaction between vector bosons is an important step in testing the validity of the Standard Model at high energies. On of the key interests is due to the necessity of the SM-Higgs for the unitarization of this process. Higgs-related as well as more general BSM effects are expected to be observable in this channel at high center-of-mass energies.

Search Channel: e+e- → νν+WW/ZZ → νν+qqqq, ECM=1TeV

Detector Benchmark: Separation of hadronic W and Z decays in a {di-boson + high E_miss} environment (incl. JES, JER). Expected limits on anomalous Quartic Gauge Couplings in (dim.-8) EFT framework.


Main observables:

Final observables: Dimension-8 EFT coefficients related to VV→V'V' vertex

Intermediate observables: QGCs, JER, JES, W/Z separation by mass Di-Boson four momenta, missing four momentum, jet content, angular distributions.


IDR plots & note:

IDR note:

Current note status (WIP, requires stash account and access rights):

https://stash.desy.de/projects/JBPUBS/repos/ildbench_qgc_note/browse/LaTeX/ILDBench_QGC_note.pdf

Current proposals for IDR plots:

I. Full Q^2_VV range:

  • Reconstructed distributions:

    View file
    namels_comp_rec_monly.pdf
    height250
    View file
    namem_m_rec.pdf
    height250

    ls_comp_rec_monly.C , m_m_rec.C

  • Fully cheated distributions:
    (Reconstructed particles belonging to initial boson, only events w/o semi-leptonic decays)
    View file
    namels_comp_icn_noSLD_monly.pdf
    height250
    View file
    namem_m_icn_noSLD.pdf
    height250

    ls_comp_icn_noSLD_monly.C , m_m_icn_noSLD.C

  • Influence of cheating individual reconstruction steps:
    View file
    namel_WW_cheating_steps.pdf
    height250
    View file
    namel_ZZ_cheating_steps.pdf
    height250

    l_WW_cheating_steps.C , l_ZZ_cheating_steps.C

II. High-Q^2_VV range (>500GeV):

Proposal for IDR figure of merit:

Simple figure of merit proposal:

Use 1D projection distributions
→ Scan with a 1D cut (all left of m_cut is reco-WW, all right of m_cut reco-ZZ)
→ Find point where confusion percentage is same for WW and ZZ (e.g. 70% of WW correctly ID'd and 70% of ZZ correctly ID'd)
→ Figure of merit: Percentage of WW (ZZ) correctly identified as WW (ZZ)

Confusion figure of merit for different cheating steps:

cheating level

Correctly identified boson pairs
[%]


full Q^2, IDR-Lhigh-Q^2, IDR-Lhigh-Q^2, IDR-S
Full reconstruction71.172.672.6
... + cheated beam-background removal79.684.083.5
... + cheated jet clustering86.385.585.1
... + cheated jet pairing to bosons88.485.785.3

... & only for events w/o
semi-leptonic decays

94.4

92.692.5
Generator level100

This figure of merit can be (roughly) used to compare to the assumption of a recent aQGC generator level study [arXiv:1607.03030].
Assumption of the generator level study:

Confusion of W→Z (Z→W) of 88%
→ Correct reconstruction of a hadronic WW (ZZ): 77.4%

People:

Jakob Beyer (DESY, Uni Hamburg, TU Dresden), reviewed by Taikan Suehara (Kyushu University)

References:

GitHub repository:

https://github.com/ILDAnaSoft/ILDbench_QGC

Talks:

Jakob Beyer :