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Status of k-factors update for Run-3 analyses

→ Europe/Zurich
Dermot Anthony Moran (CIEMAT - Centro de Investigaciones Energéticas Medioambientales y Tec. (ES)), Lourdes Urda (Centre National de la Recherche Scientifique (FR))
GMT20260306-140403_Recording_1920x1200.mp4
    • 15:00 → 15:20
      Status of k-factors for Run-3 analyses 20m
      Speaker: Mohit Vir Srivastav (Johns Hopkins University)
      LHCHWG_3_6_2026.pdf

      Minutes – LHCHWG Meeting: K-Factor Updates
      Date:March 6, 2026
      Presenter: Mohit Srivastav

      Summary

      • The ggH k-factor is computed using HNNLO, deriving corrections from LO → NLO and LO → NNLO, with NLO → NNLO obtained implicitly.

      • Updated PDF sets are used and mass points are evaluated from 100 GeV to 6 TeV.

      • Systematic uncertainties include QCD scale variations, PDF uncertainties, and αs variations, requiring large computing resources (~50k jobs).

      • For qq → ZZ, the calculation is performed with MATRIX.

      • A key issue was EW photon emission (ISR/FSR) distorting the (m_{4\ell}) distribution; after discussions with the authors, the treatment was updated and a ΔR = 0.5 photon–lepton merging (consistent with the analysis) will be used.

      • Current k-factors are derived as a function of (m_{4\ell}), with combined QCD + EW corrections preferred.

      Next Steps

      • Produce NLO samples with POWHEG for gluon-fusion signal, background, and interference to improve the modeling and potentially reduce the current ~10% uncertainty.

      • Continue interaction with the MATRIX authors to streamline photon treatment and speed up high-precision calculations.

      • Finalize systematic variations for the ggH k-factor and validate the implementation for Run-3 analyses.