A search is performed for a new resonance X decaying into a Higgs boson and a new scalar boson Y (HY) including the case where Y is assumed to be a second Higgs boson (HH), using proton-proton collision data collected at (Formula presented) 13 TeV, corresponding to an integrated luminosity of 138 fb−1. This study performs a comprehensive exploitation of the bbZZ events, encompassing the following decay topologies. One H candidate is identified through its decay into a bottom quark-antiquark pair, while the other H or the Y candidate is selected through its decay into a pair of Z bosons. One Z boson is required to decay leptonically and the other, to decay into a pair of quarks or neutrinos. Events of interest are categorized based on the Lorentz boosts of the hadronically decaying H and Z bosons. Machine-learning-based discriminants, together with the reconstructed resonance mass, are employed across the different categories to separate signal from backgrounds, and their corresponding distributions are included in a simultaneous fit. No significant deviations from the standard model predictions are observed. Upper limits at the 95% confidence level are set on the HY and HH production cross sections. For HY production, the upper limit on the cross section of the process pp → X → HY → bbZZ ranges from 500 to 5 fb, with the most stringent constraints achieved for high-mass X resonances and Y masses near the threshold for decay into a pair of massive vector bosons. This is comparable to the sensitivity achieved in other analyses, which focus on H decays to γγ or ττ and Y decays into a pair of bottom quarks or massive vector bosons. For resonant HH production, the upper limit on the cross section of pp → X → HH production is 1 pb for a high-mass resonance.

Search for a new resonance decaying to a Higgs boson and a scalar boson in events with two b jets and two Z bosons in proton-proton collisions at √ s = 13 TeV

Abbrescia, M.;Barbieri, M.;Buonsante, M.;Colaleo, A.;De Palma, M.;Elmetenawee, W.;Generoso, L.;Louka, M.;Mastrapasqua, V.;My, S.;Nenna, F.;Nuzzo, S.;Pellecchia, A.;Pompili, A.;Radogna, R.;Stamerra, A.;Troiano, D.;Venditti, R.;Zaza, A.;D'Anzi, B.;
2026-01-01

Abstract

A search is performed for a new resonance X decaying into a Higgs boson and a new scalar boson Y (HY) including the case where Y is assumed to be a second Higgs boson (HH), using proton-proton collision data collected at (Formula presented) 13 TeV, corresponding to an integrated luminosity of 138 fb−1. This study performs a comprehensive exploitation of the bbZZ events, encompassing the following decay topologies. One H candidate is identified through its decay into a bottom quark-antiquark pair, while the other H or the Y candidate is selected through its decay into a pair of Z bosons. One Z boson is required to decay leptonically and the other, to decay into a pair of quarks or neutrinos. Events of interest are categorized based on the Lorentz boosts of the hadronically decaying H and Z bosons. Machine-learning-based discriminants, together with the reconstructed resonance mass, are employed across the different categories to separate signal from backgrounds, and their corresponding distributions are included in a simultaneous fit. No significant deviations from the standard model predictions are observed. Upper limits at the 95% confidence level are set on the HY and HH production cross sections. For HY production, the upper limit on the cross section of the process pp → X → HY → bbZZ ranges from 500 to 5 fb, with the most stringent constraints achieved for high-mass X resonances and Y masses near the threshold for decay into a pair of massive vector bosons. This is comparable to the sensitivity achieved in other analyses, which focus on H decays to γγ or ττ and Y decays into a pair of bottom quarks or massive vector bosons. For resonant HH production, the upper limit on the cross section of pp → X → HH production is 1 pb for a high-mass resonance.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11586/601898
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