Heavy Higgs signal–background interference in $$gg\rightarrow VV$$ g g → V V in the Standard Model plus real singlet

Abstract

For the Standard Model extended with a real scalar singlet field, the modification of the heavy Higgs signal due to interference with the continuum background and the off-shell light Higgs contribution is studied for gg → Z Z, W W → 4 lepton processes at the Large Hadron Collider. Interference effects can range from O(10 %) to O(1) effects for integrated cross sections. Despite a strong cancellation between the heavy Higgs-continuum and the heavy Higgs-light Higgs interference, the full interference is clearly non-negligible and modifies the heavy Higgs line shape. A |M V V − M h2 | < h2 cut mitigates interference effects to O(10 %) or less. A public program that allows one to simulate the full interference is presented.

Off-shell Higgs coupling measurements in BSM scenarios

“…Most concrete realizations of BSM physics predict new physics at high energies as a unitarity-related compensator for modifications of on-shell coupling strengths. "Off-shell" measurements are therefore prime candidates to look for deviations from the Standard Model in the sense that they will be sensitive to new resonances [56][57][58][59] and will have strong implications for BSM physics in general.…”

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 MSTW2008LO [70] PDF set is used with default α s . The CKM matrix is approximated by the unit matrix, which causes a negligible error [23]. As input parameters, we use the recommendation of the LHC Higgs Cross section Working Group in appendix A of ref.…”

“…This criterion is also applied to amplitudes which are not affected by numerical instabilities, in order to obtain consistent cross section-level results. The numerical effect of this technical cut has been shown to be small [23,28]. The diagrams in figures 1-3 show the different kinematical structures that appear in the various amplitude components.…”

“…Additional details of the phase space implementation and validation in gg2VV can be found in ref. [63].…”

“…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.…”