NNLO-QCD corrections to the free b-quark decay and NLO corrections to dimension-five operators reduce uncertainties in HQE predictions for b-baryon lifetimes, yielding excellent agreement with experiment.
Contribution of the Darwin operator to non-leptonic decays of heavy quarks
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abstract
We compute the Darwin operator contribution ($1/m_b^3$ correction) to the width of the inclusive non-leptonic decay of a $B$ meson ($B^+$, $B_d$ or $B_s$), stemming from the quark flavour-changing transition $b \to q_1 \bar q_2 q_3$, where $q_1,q_2 = u, c$ and $q_3 = d, s$. The key ideas of the computation are the local expansion of the quark propagator in the external gluon field including terms with covariant derivative of the gluon field strength tensor and the standard technique of the Heavy Quark Expansion (HQE). We confirm the previously known expressions of the $1/m_b^3$ contributions to the semi-leptonic decay $b \to q_1 \ell \bar \nu_\ell$, with $\ell = e, \mu, \tau$ and of the $1/m_b^2$ contributions to the non-leptonic modes. We find that this new term can give a sizeable correction of about $- 4 \, \%$ to the non-leptonic decay width of a $B$ meson. For $B_d$ and $B_s$ mesons this turns out to be the dominant correction to the free b-quark decay, while for the $B^+$ meson the Darwin term gives the second most important correction - roughly 1/2 to 1/3 of the phase space enhanced Pauli interference contribution. Due to the tiny experimental uncertainties in lifetime measurements the incorporation of the Darwin term contribution is crucial for precision tests of the Standard Model.
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representative citing papers
Updated lifetime predictions for doubly heavy baryons and B_c meson with NNLO and NLO corrections in MS-bar, kinetic, and Upsilon mass schemes, including new hierarchies for bc states.
Updated predictions within the heavy quark expansion confirm the lifetime hierarchy τ(Ξ_cc^+) < τ(Ω_cc^+) < τ(Ξ_cc^++) with τ(Ξ_cc^++) = 0.32 ± 0.05 +0.08/-0.07 ps matching LHCb data and provide ratios for the other states.
The Heavy Flavour Averaging Group reports updated world averages for b-hadron, c-hadron, and tau-lepton properties including branching fractions, lifetimes, mixing, CP violation, and CKM elements.
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Predictions for $b$-baryon lifetimes at NNLO-QCD
NNLO-QCD corrections to the free b-quark decay and NLO corrections to dimension-five operators reduce uncertainties in HQE predictions for b-baryon lifetimes, yielding excellent agreement with experiment.
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New Predictions for the Lifetimes of Doubly Heavy Baryons and the $B_c$ Meson
Updated lifetime predictions for doubly heavy baryons and B_c meson with NNLO and NLO corrections in MS-bar, kinetic, and Upsilon mass schemes, including new hierarchies for bc states.
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Revisiting lifetimes of doubly charmed baryons
Updated predictions within the heavy quark expansion confirm the lifetime hierarchy τ(Ξ_cc^+) < τ(Ω_cc^+) < τ(Ξ_cc^++) with τ(Ξ_cc^++) = 0.32 ± 0.05 +0.08/-0.07 ps matching LHCb data and provide ratios for the other states.
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Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2023
The Heavy Flavour Averaging Group reports updated world averages for b-hadron, c-hadron, and tau-lepton properties including branching fractions, lifetimes, mixing, CP violation, and CKM elements.
- Study of doubly heavy baryon lifetimes