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Electroweak corrections to $pp \to μ^+μ^-e^+e^- + X$ at the LHC -- a Higgs background study

B. Biedermann, A. Denner, S. Dittmaier, L. Hofer, B. Jäger

TL;DR

This work presents the first full NLO electroweak calculation for pp → μ+μ−e+e−+X at the LHC, incorporating all off-shell Z/γ contributions. It employs a complex-mass scheme and two independent computational approaches to ensure gauge invariance and IR finiteness. The results show that while photonic corrections can induce large tails in certain distributions, the dominant weak corrections are about 5% and exhibit a sign change near the ZZ threshold, significantly impacting Higgs-boson related observables. The study demonstrates the necessity of including off-shell EW effects for precision background modeling in Higgs analyses and provides differential distributions essential for experimental interpretations.

Abstract

The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state $μ^+μ^-e^+e^-$, we study differential cross sections that are particularly interesting for Higgs-boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W/Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular a sign change between the regions of resonant Z-pair production and the Higgs signal.

Electroweak corrections to $pp \to μ^+μ^-e^+e^- + X$ at the LHC -- a Higgs background study

TL;DR

This work presents the first full NLO electroweak calculation for pp → μ+μ−e+e−+X at the LHC, incorporating all off-shell Z/γ contributions. It employs a complex-mass scheme and two independent computational approaches to ensure gauge invariance and IR finiteness. The results show that while photonic corrections can induce large tails in certain distributions, the dominant weak corrections are about 5% and exhibit a sign change near the ZZ threshold, significantly impacting Higgs-boson related observables. The study demonstrates the necessity of including off-shell EW effects for precision background modeling in Higgs analyses and provides differential distributions essential for experimental interpretations.

Abstract

The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state , we study differential cross sections that are particularly interesting for Higgs-boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W/Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular a sign change between the regions of resonant Z-pair production and the Higgs signal.

Paper Structure

This paper contains 4 sections, 11 equations, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. General setup of the calculation
  3. Input and event selection
  4. Numerical results

Figures (3)

  • Figure 1: Invariant-mass distribution of the $\mu^+\mu^-$ system in $\mathrm{p}$p$\mathrm{p}$p$\to\mu^+\mu^-\mathrm{e^+}$e^+$\mathrm{e^-}$e^-$+X$ including NLO EW corrections (upper panel), and relative EW and purely weak corrections at NLO (lower panel).
  • Figure 2: Four-lepton invariant-mass distribution in $\mathrm{p}$p$\mathrm{p}$p$\to\mu^+\mu^-\mathrm{e^+}$e^+$\mathrm{e^-}$e^-$+X$ including NLO EW corrections (upper panel), and relative EW and purely weak corrections at NLO (lower panel).
  • Figure 3: Distribution in the angle $\phi$ between the two $\mathrm{Z}$Z$$-boson decay planes in $\mathrm{p}$p$\mathrm{p}$p$\to\mu^+\mu^-\mathrm{e^+}$e^+$\mathrm{e^-}$e^-$+X$ including NLO EW corrections (upper panel), and relative EW and purely weak corrections at NLO (lower panel).