Signal-background interference in gg --> H --> VV

TL;DR

The paper investigates resonance-continuum interference between the gluon-fusion Higgs signal $gg\rightarrow H\rightarrow VV$ and the continuum background $gg\rightarrow VV$ for a heavy Higgs with $M_H=400$ GeV at the LHC. Using leading-order calculations with leptonic decays and realistic selection cuts via the gg2WW and gg2ZZ tools, the authors quantify interference with measurable metrics $R_1$ and $R_2$ across $\sqrt{s}=7$ and 14 TeV. They find interference effects can reach ~5% at 7 TeV and approach ~10% at 14 TeV, with the size and sign of interference depending on the final state and applied cuts; specific ZZ cuts can suppress interference to about 1%. The results underscore that interference is non-negligible and can be enhanced by selective cuts, signaling that it must be accounted for in LHC Higgs analyses and searches for heavy resonances.

Abstract

The resonance-continuum interference between the SM Higgs search signal process gg --> H --> VV (V=W,Z) and the irreducible background process gg --> VV is studied at leading order for integrated cross sections and differential distributions in pp collisions at \sqrt{s}=7 TeV and 14 TeV for M_H=400 GeV. Leptonic weak boson decays are included, and realistic experimental selection cuts are applied.

Figures (6)

• Figure 1: Representative Feynman graphs for the Higgs signal process (left) and the $q\bar{q}$- (centre) and $gg$-initiated (right) continuum background processes at LO.
• Figure 2: Representative triangle graphs that formally contribute to gluon-induced $VV$ continuum production and decay.
• Figure 3: Differential cross section distributions for $gg\ (\to H)\to W^-W^+\to l\bar{\nu}_l\bar{l'}\nu_{l'}$ in $pp$ collisions at $\sqrt{s} = 7$ TeV for $M_H=400$ GeV and a single lepton flavour combination calculated at LO. The $p_{Tl}$ [GeV] (left) and $\eta_l$ (right) distributions are shown. Standard cuts are applied (see main text). fb is used as cross section unit.
• Figure 4: $p_{Tl,\text{min}}$ [GeV] (left) and $p_{Tl,\text{max}}$ [GeV] (right) distributions. Other details as in Fig. \ref{['fig:WW1']}.
• Figure 5: $M_{l\bar{l'}}$ [GeV] (left) and $\Delta\phi_{l\bar{l'}}$ [$^\circ$] (right) distributions. Other details as in Fig. \ref{['fig:WW1']}.