Inadequacy of zero-width approximation for a light Higgs boson signal

By N. Kauer, G. Passarino. 2012

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A bstractIn the Higgs search at the LHC, a light Higgs boson $ \left( {{115}\,{\text{GeV}} \lesssim {M_{\text{H}}} \lesssim {13}0\,{\text{GeV}}} \right) $ is not excluded by experimental data. In this mass range, the width of the Standard Model Higgs boson is more than four orders of magnitude smaller than its mass. The zero-width approximation is hence expected to be an excellent approximation. We show that this is not always the case. The inclusion of off-shell contributions is essential to obtain an accurate Higgs signal normalisation at the 1% precision level. For gg (→ H) → VV, V = W,Z, $ \mathcal{O} $(10 %) corrections occur due to an enhanced Higgs signal in the region MV V> 2 MV, where also sizable Higgs-continuum interference occurs. We discuss how experimental selection cuts can be used to exclude this region in search channels where the Higgs invariant mass cannot be reconstructed. We note that the H → V V decay modes in weak boson fusion are similarly affected.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/c76af212447a3fe9d3afbf9ff37aeb2173de1ba1

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In Nuclear and High Energy Physics

Citations in the corpus

Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC (2012, neutral): “The impact of the interference between a Higgs signal and the non-resonant gg → ZZ ( ) background is small and becomes negligible for m H < 2 m Z [94].”
Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\o (2015, neutral): “e factors j. The signal-strength measurements of o-shell Higgs boson production [24], on the other hand, is assumed to only depend on the coupling-strength scale factors and not on the total width [55,56], i.e. ˙o(i !H !f) ˘2 i;o 2 f;o (9) where the additional assumption of non-running coupling-st”
Measurements of the properties of the Higgs-like boson in the four lepton decay channel with the ATLAS detector using 25 fb$^{-1}$ of proton-proton collision data (2013, methodology): “The ZZ(∗) continuum background is modelled using P [53] for quark-antiquark annihilation and gg2ZZ [54] for gluon-gluon contributions, normalised to the MCFM prediction [55].”
Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC (2013, neutral): “gg → ZZ∗ gg2ZZ [43,45] + HERWIG W γ + jets ALPGEN + HERWIG”
Higgs Boson studies at future particle colliders (2019, background): “ecay into a ZZ ﬁnal state: gg !H !ZZ, where the H boson is on shell (and at least one of the ﬁnal state Z off shell) and gg !ZZ with two on-shell Z bosons, where the H boson contribution is off shell [87]. The ratio of the off-shell over the on-shell rate is directly proportional to the total width ”
Automated event generation for loop-induced processes (2015, neutral): “1% [64] †d.”
Higgs Physics at the HL-LHC and HE-LHC (2019, methodology): “In the V V decay channel though there is a sizeable contribution from the off-shell s mH 2 region [487]: indeed, Higgs decay to vector bosons is strongly enhanced at high energy.”
Soft gluon resummation in the signal-background interference process of gg(→ h∗) → ZZ (2015, methodology): “Though the theoretical prediction for the pure signal process is known up to nextto-leading order (NLO) and next-to-next-to-leading logarithmic (NNLL) level with the finite top quark mass [20–22], the interference process is predicted only at leading order (LO) [7, 8, 23].”
Mass effects in the Higgs-gluon coupling: boosted vs. off-shell production (2014, methodology): “As mentioned it was recently proposed to use information from the off-shell regime as a direct measurement of the Higgs width [53–57].”
Combined measurements of Higgs boson production and decay using up to $80$ fb$^{-1}$ of proton-proton collision data at $\sqrt{s}=$ 13 TeV collected with the ATLAS experiment (2019, neutral): “[134,135], σoffði → H → fÞ ∼ κ(2)i;off × κ(2)f;off .”
Handbook of LHC Higgs Cross Sections: 3. Higgs Properties (2013, methodology): “In Sections 3.5.2 and 3.5.3, results for gg (→ H)→ 4 leptons including Higgs-continuum interference effects calculated withGG2VV [86] are presented.”
Bounding the Higgs width at the LHC using full analytic results for gg → e−e+μ−μ+ (2013, methodology): “More recently, the public codes gg2ZZ [30] and gg2VV [9, 31] were developed that include the full mass dependence in the fermion loop, and leptonic decays of the Z/γ∗.”
Constraints on the spin-parity and anomalous HVV couplings of the Higgs boson in proton collisions at 7 and 8 TeV (2015, background): “The number of estimated background and signal events, and the number of observed candidates after the final selection in data in the narrow mass region around 125.6 GeV is given in Table 3.”
Dark Matter through the Higgs portal (2019, background): “However, rather recently, it was noticed [211,212] that in the production channel pp→ V V → 4f with V =W,Z, a large fraction of the Higgs–mediated cross section lies in the high–mass tail where the invariant mass of the V V system is larger than 2MV .”