Direct constraint on the Higgs-charm coupling from a search for Higgs boson decays into charm quarks with the ATLAS detector



Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H
et al (show 2840 more authors) (2022) Direct constraint on the Higgs-charm coupling from a search for Higgs boson decays into charm quarks with the ATLAS detector. EUROPEAN PHYSICAL JOURNAL C, 82 (8). 717-.

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Abstract

<jats:title>Abstract</jats:title><jats:p>A search for the Higgs boson decaying into a pair of charm quarks is presented. The analysis uses proton–proton collisions to target the production of a Higgs boson in association with a leptonically decaying <jats:italic>W</jats:italic> or <jats:italic>Z</jats:italic> boson. The dataset delivered by the LHC at a centre-of-mass energy of "Equation missing"<!-- image only, no MathML or LaTex --> and recorded by the ATLAS detector corresponds to an integrated luminosity of 139 <jats:inline-formula><jats:alternatives><jats:tex-math>$$\text{ fb}^{-1}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:msup> <mml:mtext>fb</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula>. Flavour-tagging algorithms are used to identify jets originating from the hadronisation of charm quarks. The analysis method is validated with the simultaneous measurement of <jats:italic>WW</jats:italic>, <jats:italic>WZ</jats:italic> and <jats:italic>ZZ</jats:italic> production, with observed (expected) significances of 2.6 (2.2) standard deviations above the background-only prediction for the <jats:inline-formula><jats:alternatives><jats:tex-math>$$(W/Z)Z(\rightarrow c{\bar{c}})$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>W</mml:mi> <mml:mo>/</mml:mo> <mml:mi>Z</mml:mi> <mml:mo>)</mml:mo> <mml:mi>Z</mml:mi> <mml:mo>(</mml:mo> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mover> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>)</mml:mo> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> process and 3.8 (4.6) standard deviations for the <jats:inline-formula><jats:alternatives><jats:tex-math>$$(W/Z)W(\rightarrow cq)$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>W</mml:mi> <mml:mo>/</mml:mo> <mml:mi>Z</mml:mi> <mml:mo>)</mml:mo> <mml:mi>W</mml:mi> <mml:mo>(</mml:mo> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mi>q</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> process. The <jats:inline-formula><jats:alternatives><jats:tex-math>$$(W/Z)H(\rightarrow c {\bar{c}})$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>W</mml:mi> <mml:mo>/</mml:mo> <mml:mi>Z</mml:mi> <mml:mo>)</mml:mo> <mml:mi>H</mml:mi> <mml:mo>(</mml:mo> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mover> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>)</mml:mo> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> search yields an observed (expected) upper limit of 26 (31) times the predicted Standard Model cross-section times branching fraction for a Higgs boson with a mass of "Equation missing"<!-- image only, no MathML or LaTex -->, corresponding to an observed (expected) constraint on the charm Yukawa coupling modifier <jats:inline-formula><jats:alternatives><jats:tex-math>$$|\kappa _c| &lt; 8.5~(12.4)$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mrow> <mml:mo>|</mml:mo> </mml:mrow> <mml:msub> <mml:mi>κ</mml:mi> <mml:mi>c</mml:mi> </mml:msub> <mml:mrow> <mml:mo>|</mml:mo> <mml:mo>&lt;</mml:mo> <mml:mn>8.5</mml:mn> <mml:mspace /> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>12.4</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula>, at the 95% confidence level. A combination with the ATLAS <jats:inline-formula><jats:alternatives><jats:tex-math>$$(W/Z)H, H\rightarrow b{\bar{b}}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>W</mml:mi> <mml:mo>/</mml:mo> <mml:mi>Z</mml:mi> <mml:mo>)</mml:mo> <mml:mi>H</mml:mi> <mml:mo>,</mml:mo> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>b</mml:mi> <mml:mover> <mml:mrow> <mml:mi>b</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> analysis is performed, allowing the ratio <jats:inline-formula><jats:alternatives><jats:tex-math>$$\kappa _c / \kappa _b$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>κ</mml:mi> <mml:mi>c</mml:mi> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>κ</mml:mi> <mml:mi>b</mml:mi> </mml:msub> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> to be constrained to less than 4.5 at the 95% confidence level, smaller than the ratio of the b- and c-quark masses, and therefore determines the Higgs-charm coupling to be weaker than the Higgs-bottom coupling at the 95% confidence level.</jats:p>

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 14 Sep 2022 15:15
Last Modified: 18 Mar 2024 04:01
DOI: 10.1140/epjc/s10052-022-10588-3
Open Access URL: https://link.springer.com/article/10.1140/epjc/s10...
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3164718