Gluon-inducedW-boson pair production at the LHC

Abstract

Pair production of W bosons constitutes an important background to Higgs boson and new physics searches at the Large Hadron Collider LHC. We have calculated the loop-induced gluon-fusion process gg → W * W * → leptons, including intermediate light and heavy quarks and allowing for arbitrary invariant masses of the W bosons. While formally of next-to-next-to-leading order, the gg → W * W * → leptons process is enhanced by the large gluon flux at the LHC and by experimental Higgs search cuts, and increases the next-to-leading order W W background estimate for Higgs searches by about 30%. We have extended our previous calculation to include the contribution from the intermediate topbottom massive quark loop and the Higgs signal process. We provide updated results for cross sections and differential distributions and study the interference between the different gluon scattering contributions. We describe important analytical and numerical aspects of our calculation and present the public GG2WW event generator.

The gauge-Higgs legacy of the LHC Run I

“…We compare these results to the experimental predictions, defining a bin-by-bin correction factor. It accounts for phase-space dependent corrections either from detector effects or from higher order corrections [67][68][69][70][71][72]. These correction factors we apply to our simulated W V distributions in the presence of the anomalous TGVs, based on an in-house MadGraph5 implementation of the operators constructed with FeynRules [73].…”

“…[57]. To ensure this, we introduce a bin-by-bin correction factor to account for differences in the selection procedure because of detector effects as well as higher order corrections to the cross section prediction [67][68][69][70][71][72].…”

Interference effects for H → W W → ℓ ν q q ¯ ′ $$ H\to W\;W\to \ell \nu q{\overline{q}}^{\prime } $$ and H → Z Z → ℓ ℓ ¯ q q ¯ $$ H\to ZZ\to \ell \overline{\ell}q\overline{q} $$ searches in gluon fusion at the LHC

“…The Z boson vector coupling contribution vanishes for the same reason. Regarding the Z boson axial-vector coupling contribution: in the case of four massless final state leptons, the sum of all triangle diagrams has analytically been shown to vanish for V = W [21] (and V = Z if m q = 0 in the loop [57]). For V = W this result carries over to the semileptonic decay mode, because the W ff coupling is flavour independent (V CKM = 1).…”

“…In the SM, interference between the Higgs signal and continuum background in gg (→ H) → V V (V = W, Z) and including fully leptonic decays has been studied in refs. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. 1 Higgs-continuum interference results for a heavy SM Higgs boson have been presented in refs.…”

Measurement of theW+W−Cross Section ins=7 TeVAad1, Abbott2, Abdallah3 et al. 2011Phys. Rev. Lett.

“…The q " q ! W þ W À signal is simulated up to next-to-leading order in QCD with MC@NLO [8] and the gluon fusion process is simulated with GG2WW [9]; the CTEQ6.6 [10] and CTEQ6M [11] parton distribution functions (PDFs), respectively, are used. HERWIG [12] is used to model W leptonic decays, parton showers, and hadronization, and JIMMY [13] is used to simulate the underlying event.…”