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QCD corrections to hadronic WWZ production with leptonic decays

V. Hankele, D. Zeppenfeld

TL;DR

This work addresses the need for precise theoretical predictions of WWZ production with leptonic decays at the LHC, both as a SM background and as a probe of quartic electroweak couplings. The authors perform a full NLO QCD calculation for the 2→6 leptonic final state, including Higgs/off-shell contributions and spin correlations, using Catani–Seymour dipole subtraction and helicity amplitudes, and implement it in the VBFNLO Monte Carlo framework. They find a large overall NLO enhancement (K ≈ 1.7) with significant shape changes in distributions and non-negligible scale uncertainties, highlighting the inadequacy of LO predictions. The differential K-factors vary across phase space (e.g., rising with lepton pT to ~2, and m4ℓ around 1.4–1.9), while pentagon contributions are small (~1–2%). The results provide a practical, publicly available tool for accurate WWZ modeling in LHC analyses and for improving constraints on quartic electroweak couplings.

Abstract

Multi-lepton signatures appear in many new physics searches at the Large Hadron Collider. We here consider WWZ production with subsequent leptonic decay of the three vector bosons as a SM source of multi-lepton events. We have calculated the next-to-leading order QCD corrections for the full $p p\to 6$ lepton production cross sections in hadronic collisions. Results have been implemented in the form of a flexible parton-level Monte-Carlo program which allows to calculate the QCD corrections for arbitrary distributions and acceptance cuts.

QCD corrections to hadronic WWZ production with leptonic decays

TL;DR

This work addresses the need for precise theoretical predictions of WWZ production with leptonic decays at the LHC, both as a SM background and as a probe of quartic electroweak couplings. The authors perform a full NLO QCD calculation for the 2→6 leptonic final state, including Higgs/off-shell contributions and spin correlations, using Catani–Seymour dipole subtraction and helicity amplitudes, and implement it in the VBFNLO Monte Carlo framework. They find a large overall NLO enhancement (K ≈ 1.7) with significant shape changes in distributions and non-negligible scale uncertainties, highlighting the inadequacy of LO predictions. The differential K-factors vary across phase space (e.g., rising with lepton pT to ~2, and m4ℓ around 1.4–1.9), while pentagon contributions are small (~1–2%). The results provide a practical, publicly available tool for accurate WWZ modeling in LHC analyses and for improving constraints on quartic electroweak couplings.

Abstract

Multi-lepton signatures appear in many new physics searches at the Large Hadron Collider. We here consider WWZ production with subsequent leptonic decay of the three vector bosons as a SM source of multi-lepton events. We have calculated the next-to-leading order QCD corrections for the full lepton production cross sections in hadronic collisions. Results have been implemented in the form of a flexible parton-level Monte-Carlo program which allows to calculate the QCD corrections for arbitrary distributions and acceptance cuts.

Paper Structure

This paper contains 4 sections, 8 equations, 4 figures.

Table of Contents

  1. Introduction
  2. The Calculation
  3. Results
  4. Conclusions

Figures (4)

  • Figure 1: Some representative tree-level Feynman diagrams of the process $p p \to 4 \, \ell + 2 \, \nu$. They show the three different topologies appearing in this calculation.
  • Figure 2: Left:Scale dependence of the total cross section for $p p \to WWZ \to 4 \, \ell+=\hbox{$p$}p \hbox{/} _T$ at LO and NLO for $m_H = 120 \ \mathrm{GeV}$ and the cuts of Eq. (\ref{['eq:cuts']}). The factorization and renormalization scales are taken at a fixed value which is varied in the range from $0.5 \cdot m_Z$ to $10 \cdot m_Z$.Right:Same as in the left panel but for the different NLO contributions.
  • Figure 3: Left:Transverse momentum distribution of the highest-$p_T$ charged lepton for $m_H = 120 \ \mathrm{GeV}$, $\mu_F = \mu_R = m_{WWZ}$ as given in Eq. (\ref{['eq:WWZmass']}) and the cuts given in Eq. (\ref{['eq:cuts']}) at LO and NLO.Right:Differential $K$-factor as defined in Eq. (\ref{['eq:kfactor']}) for the two distributions in the left panel.
  • Figure 4: Left:Invariant mass distribution of the four charged leptons for $m_H = 120 \ \mathrm{GeV}$, $\mu_F = \mu_R = m_{WWZ}$ and the cuts given in Eq. (\ref{['eq:cuts']}) at LO and NLO.Right:Differential $K$-factor as defined in Eq. (\ref{['eq:kfactor']}) for the two distributions in the left panel.