<p>Precise measurements of Higgs decays into quarks and gluons are essential for probing the Yukawa couplings of the Higgs boson and testing the flavor structure of the Standard Model. We investigate the process <i>e</i><sup>+</sup><i>e</i><sup>−</sup> → <i>ZH</i> at <InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math display="inline"> <msqrt> <mi>s</mi> </msqrt> </math></EquationSource> <EquationSource Format="TEX">\( \sqrt{s} \)</EquationSource> </InlineEquation> = 240 GeV at a future <i>e</i><sup>+</sup><i>e</i><sup>−</sup> Higgs factory, taking the CEPC design as a benchmark. The analysis focuses on events with <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math display="inline"> <mi>Z</mi> <mo>→</mo> <mi>ν</mi> <mover accent="true"> <mi>ν</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( Z\to \nu \overline{\nu} \)</EquationSource> </InlineEquation> and hadronic Higgs decays <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math display="inline"> <mi>H</mi> <mo>→</mo> <mi>b</mi> <mover accent="true"> <mi>b</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( H\to b\overline{b} \)</EquationSource> </InlineEquation>, <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math display="inline"> <mi>c</mi> <mover accent="true"> <mi>c</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( c\overline{c} \)</EquationSource> </InlineEquation>, <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math display="inline"> <mi>s</mi> <mover accent="true"> <mi>s</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( s\overline{s} \)</EquationSource> </InlineEquation> and <i>gg</i>. Jet flavor is identified using state-of-the-art particle-level deep neural network taggers (ParticleNet, Particle Transformer and More-Interaction Particle Transformer), whose per-jet outputs are combined with global event observables in a two-stage analysis employing XGBoost classifiers to separate the four Higgs decay modes from the dominant two- and four-fermion Standard Model backgrounds. Assuming an integrated luminosity of 20 ab<sup>−1</sup>, we obtain projected relative precision on <i>σ</i>(<i>ZH</i>) × Br(<i>H</i> → <i>X</i>) of 0.17% for <i>X</i> = <InlineEquation ID="IEq6"> <EquationSource Format="MATHML"><math display="inline"> <mi>b</mi> <mover accent="true"> <mi>b</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( b\overline{b} \)</EquationSource> </InlineEquation>, 1.06% for <InlineEquation ID="IEq7"> <EquationSource Format="MATHML"><math display="inline"> <mi>c</mi> <mover accent="true"> <mi>c</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( c\overline{c} \)</EquationSource> </InlineEquation>, 0.50% for <i>gg</i> and 68% for <InlineEquation ID="IEq8"> <EquationSource Format="MATHML"><math display="inline"> <mi>s</mi> <mover accent="true"> <mi>s</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( s\overline{s} \)</EquationSource> </InlineEquation>. Compared with the CEPC published results, the precisions for <InlineEquation ID="IEq9"> <EquationSource Format="MATHML"><math display="inline"> <mi>H</mi> <mo>→</mo> <mi>c</mi> <mover accent="true"> <mi>c</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( H\to c\overline{c} \)</EquationSource> </InlineEquation> and <i>H</i> → <i>gg</i> are improved by about 43% and 29%, respectively. For <InlineEquation ID="IEq10"> <EquationSource Format="MATHML"><math display="inline"> <mi>H</mi> <mo>→</mo> <mi>s</mi> <mover accent="true"> <mi>s</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">\( H\to s\overline{s} \)</EquationSource> </InlineEquation> we present a quantitative sensitivity estimation corresponding to a statistical significance of about 1.5<i>σ</i>. These results highlight the potential of deep-learning-based jet flavor tagging for precision studies of Higgs decays at future <i>e</i><sup>+</sup><i>e</i><sup>−</sup> Higgs factories.</p>

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Deep-learning jet flavor tagging for precision hadronic Higgs measurements at future e+e Higgs factories

  • Xinzhu Wang,
  • Yifan Zhu,
  • Chunxiang Zhu,
  • Jianfeng Jiang,
  • Manqi Ruan,
  • Kun Wang,
  • Haijun Yang,
  • Yongfeng Zhu

摘要

Precise measurements of Higgs decays into quarks and gluons are essential for probing the Yukawa couplings of the Higgs boson and testing the flavor structure of the Standard Model. We investigate the process e+eZH at s \( \sqrt{s} \) = 240 GeV at a future e+e Higgs factory, taking the CEPC design as a benchmark. The analysis focuses on events with Z ν ν ¯ \( Z\to \nu \overline{\nu} \) and hadronic Higgs decays H b b ¯ \( H\to b\overline{b} \) , c c ¯ \( c\overline{c} \) , s s ¯ \( s\overline{s} \) and gg. Jet flavor is identified using state-of-the-art particle-level deep neural network taggers (ParticleNet, Particle Transformer and More-Interaction Particle Transformer), whose per-jet outputs are combined with global event observables in a two-stage analysis employing XGBoost classifiers to separate the four Higgs decay modes from the dominant two- and four-fermion Standard Model backgrounds. Assuming an integrated luminosity of 20 ab−1, we obtain projected relative precision on σ(ZH) × Br(HX) of 0.17% for X = b b ¯ \( b\overline{b} \) , 1.06% for c c ¯ \( c\overline{c} \) , 0.50% for gg and 68% for s s ¯ \( s\overline{s} \) . Compared with the CEPC published results, the precisions for H c c ¯ \( H\to c\overline{c} \) and Hgg are improved by about 43% and 29%, respectively. For H s s ¯ \( H\to s\overline{s} \) we present a quantitative sensitivity estimation corresponding to a statistical significance of about 1.5σ. These results highlight the potential of deep-learning-based jet flavor tagging for precision studies of Higgs decays at future e+e Higgs factories.