Search for a new heavy scalar particle decaying into a Higgs boson and a new scalar singlet in final states with one or two light leptons and a pair of τ-leptons with the ATLAS detector



Aad, G, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS
et al (show 2919 more authors) (2023) Search for a new heavy scalar particle decaying into a Higgs boson and a new scalar singlet in final states with one or two light leptons and a pair of τ-leptons with the ATLAS detector. Journal of High Energy Physics, 2023 (10). 9-.

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Abstract

<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>A search for a new heavy scalar particle <jats:italic>X</jats:italic> decaying into a Standard Model (SM) Higgs boson and a new singlet scalar particle <jats:italic>S</jats:italic> is presented. The search uses a proton-proton (<jats:italic>pp</jats:italic>) collision data sample with an integrated luminosity of 140 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> recorded at a centre-of-mass energy of <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 13 TeV with the ATLAS detector at the Large Hadron Collider. The most sensitive mass parameter space is explored in <jats:italic>X</jats:italic> mass ranging from 500 to 1500 GeV, with the corresponding <jats:italic>S</jats:italic> mass in the range 200–500 GeV. The search selects events with two hadronically decaying <jats:italic>τ</jats:italic>-lepton candidates from <jats:italic>H</jats:italic> → <jats:italic>τ</jats:italic><jats:sup>+</jats:sup><jats:italic>τ</jats:italic><jats:sup><jats:italic>−</jats:italic></jats:sup> decays and one or two light leptons (<jats:italic>ℓ</jats:italic> = <jats:italic>e</jats:italic>, <jats:italic>μ</jats:italic>) from <jats:italic>S</jats:italic> → <jats:italic>VV</jats:italic> (<jats:italic>V</jats:italic> = <jats:italic>W</jats:italic>, <jats:italic>Z</jats:italic>) decays while the remaining <jats:italic>V</jats:italic> boson decays hadronically or to neutrinos. A multivariate discriminant based on event kinematics is used to separate the signal from the background. No excess is observed beyond the expected SM background and 95% confidence level upper limits between 72 fb and 542 fb are derived on the cross-section <jats:italic>σ</jats:italic>(<jats:italic>pp</jats:italic> → <jats:italic>X</jats:italic> → <jats:italic>SH</jats:italic>) assuming the same SM-Higgs boson-like decay branching ratios for the <jats:italic>S</jats:italic> → <jats:italic>VV</jats:italic> decay. Upper limits on the visible cross-sections <jats:italic>σ</jats:italic>(<jats:italic>pp</jats:italic> → <jats:italic>X</jats:italic> → <jats:italic>SH</jats:italic> → <jats:italic>WWττ</jats:italic>) and <jats:italic>σ</jats:italic>(<jats:italic>pp</jats:italic> → <jats:italic>X</jats:italic> → <jats:italic>SH</jats:italic> → <jats:italic>ZZττ</jats:italic>) are also set in the ranges 3–26 fb and 6–33 fb, respectively.</jats:p>

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 Feb 2024 09:35
Last Modified: 18 Mar 2024 03:34
DOI: 10.1007/jhep10(2023)009
Open Access URL: https://link.springer.com/article/10.1007/JHEP10(2...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3178724