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<p>Theory predictions of heavy-hadron lifetime ratios critically depend on precise determinations of the dimension-six spectator effects arising from the double insertion of the weak effective |∆<i>B</i>| = 1 Hamiltonian. In the presence of beyond-standard-model (BSM) operators, the resulting ∆<i>B</i> = 0 Hamiltonian features additional four-quark operators whose matrix elements need to be determined using non-perturbative methods. We present for the first time results for the non-perturbative hadronic matrix elements of the four-quark operators relevant for the description of the meson lifetime ratio <i>τ</i> (<i>B</i><sup>+</sup>) /<i>τ</i> (<i>B</i><sub><i>d</i></sub>), obtained using heavy-quark effective theory (HQET) sum rules with the full BSM effective Hamiltonian. In addition, we recompute and update the bag parameters for the Standard Model operators.</p>

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HQET sum rules for matrix elements of dimension-six four-quark operators for meson lifetimes within and beyond the Standard Model

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年4月10日

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  • Matthew Black,
  • Martin Lang,
  • Alexander Lenz,
  • Zachary Wüthrich

摘要

Theory predictions of heavy-hadron lifetime ratios critically depend on precise determinations of the dimension-six spectator effects arising from the double insertion of the weak effective |∆B| = 1 Hamiltonian. In the presence of beyond-standard-model (BSM) operators, the resulting ∆B = 0 Hamiltonian features additional four-quark operators whose matrix elements need to be determined using non-perturbative methods. We present for the first time results for the non-perturbative hadronic matrix elements of the four-quark operators relevant for the description of the meson lifetime ratio τ (B+) /τ (Bd), obtained using heavy-quark effective theory (HQET) sum rules with the full BSM effective Hamiltonian. In addition, we recompute and update the bag parameters for the Standard Model operators.