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More than a Lifetime: Towards Precision Predictions for $B$-Meson Decays in the Standard Model and Beyond

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Ali Mohamed

High Energy Physics - Phenomenology · Submitted 18 Oct 2026 · Published version · 128 references

Pith's verdict: 这篇博士论文首次完成了非轻子b衰变HQE中dim-7两夸克算子的完整匹配系数计算，并提供了一个模型无关的BSM框架，是重味理论领域的扎实贡献。

T0 · AI review

How this review was made: An AI referee (deepseek/deepseek-v4-flash) read the paper on October 20, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

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arXiv ID2610.25311 (version 1)
Pith IDA6R77WTB, Pith's permanent record of this paper and its review
CitationAli Mohamed. "More than a Lifetime: Towards Precision Predictions for $B$-Meson Decays in the Standard Model and Beyond." arXiv:2610.25311 (2026). https://pith.science/paper/A6R77WTB
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The paper

The paper claims

This thesis completes the leading-order dimension-seven heavy-quark expansion for non-leptonic $b\to c\bar{u}d$ and $b\to c\bar{c}s$, and extends the Darwin contribution to a model-independent BSM framework, including the previously…

The reading

This thesis aims to improve theoretical predictions for inclusive non-leptonic $B$-meson lifetimes within the Heavy Quark Expansion (HQE). It provides the first complete leading-order calculation of the dimension-seven two-quark contributions ($1/m_b^4$ corrections) for the CKM-favored transitions $b\to c\bar{u}d$ and $b\to c\bar{c}s$. Additionally, it extends the dimension-six Darwin contribution to a model-independent beyond-the-Standard-Model (BSM) effective Hamiltonian, deriving the full matching coefficients for two-quark and four-quark operators, including the previously missing weak-annihilation contributions. As a special case, this yields the missing dimension-five and dimension-six contributions from SM QCD-penguin operators, further improving the theoretical precision of HQE predictions. Finally, it applies the HQE and light-cone sum rules to the B-Mesogenesis model, connecting baryon asymmetry and dark matter to exotic $B$ decays, and identifies kinematic regions where power-suppressed terms exceed leading terms, indicating limits of the HQE's applicability.

What carries the argument

The Heavy Quark Expansion (HQE) using the background field method with Fock-Schwinger gauge expansion of the quark propagator, and Light-Cone Sum Rules (LCSR) with $B$-meson distribution amplitudes for exclusive form factors form the central framework.

Extended reading notes

Core claim

The thesis provides the complete leading-order dimension-seven two-quark matching coefficients for $b\to c\bar{u}d$ and $b\to c\bar{c}s$ transitions, and the complete dimension-six two-quark and four-quark matching coefficients for a general model-independent BSM effective Hamiltonian, including the previously missing weak-annihilation contributions. For the SM, this also yields the previously missing dimension-five and dimension-six contributions from QCD-penguin operators. In the B-Mesogenesis analysis, the HQE and LCSR predictions constrain the dark-sector parameter space and reveal that power-suppressed terms can dominate over leading terms, signaling a breakdown of the HQE in certain kinematic regions.

Load-bearing premise

The LCSR predictions for $B\to p$ form factors rely on the assumption of quark-hadron duality above an effective threshold, which is weaker than local duality and introduces significant uncertainties.

Editorial extensions

If this is right

  • The dimension-seven coefficients provide the next-order HQE corrections needed to test the convergence of the expansion for $B$ lifetimes, enabling more precise SM predictions.
  • The model-independent BSM matching coefficients allow global fits of $B$ lifetime ratios to constrain new-physics Wilson coefficients from non-leptonic decays.
  • The missing weak-annihilation and penguin contributions complete the SM prediction at dimension six, reducing theoretical uncertainties in lifetime ratios.
  • The B-Mesogenesis analysis shows that for heavy dark fermion masses, the OPE can break down, providing a caveat for inclusive calculations in such models.
  • The exclusive $B^+\to p\psi$ branching fraction lower bound derived from inclusive constraints can be tested at Belle II.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The strong operator dependence of the HQE hierarchy observed in B-Mesogenesis suggests that lifetime ratios could distinguish between different new-physics scenarios if the HQE can be controlled.
  • The cancellation of triple-gluon contributions in the B-Mesogenesis LCSR due to the Ioffe current may simplify form factor calculations for other baryonic $B$ decays.
  • The regions where subleading terms exceed leading terms in the B-Mesogenesis model provide a concrete test case for the limitations of the OPE, which could inform similar analyses in other heavy-particle decays.
Original abstract

This thesis investigates B-meson lifetimes as probes of Standard Model (SM) dynamics and physics beyond the SM (BSM), employing the Heavy Quark Expansion (HQE) and light-cone sum rules (LCSR). Within the HQE, we calculate at leading order in QCD the complete dimension-seven two-quark contributions to the CKM-favoured non-leptonic transitions $b\to c\bar{u}d$ and $b\to c\bar{c}s$, providing analytical Wilson coefficients for the $1/m_b^4$ corrections. We then extend the dimension-six Darwin contribution to a model-independent BSM framework, deriving the Wilson coefficients through order $1/m_b^3$ for a general non-leptonic effective Hamiltonian. We also determine the corresponding dimension-six four-quark weak annihilation contributions. As a special case, our results provide previously missing dimension-five and dimension-six contributions induced by SM QCD-penguin operators. Finally, we investigate B-mesogenesis, which connects the cosmic matter-antimatter asymmetry and dark matter to exotic B-meson decays. We study inclusive decay rates and lifetime ratios within the HQE and exclusive $B^+\to p\psi$ decays using LCSR. Comparisons with experimental constraints from BaBar, Belle and Belle II restrict the allowed parameter space. We also identify kinematic regions where power-suppressed contributions exceed the leading terms, highlighting limitations of the HQE. Together, these studies advance the theoretical understanding of heavy-hadron lifetimes, strengthen the bridge between precision flavour physics and physics beyond the SM, and open new avenues for probing the interplay between heavy-quark dynamics and the dark sector.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-10-20: 1 request, 7,753 input tokens.

What the abstract itself states, as probabilities: claims first 0.16 · states limitation 0.94 · human participants 0.01 · controlled comparison 0.06 · randomized assignment 0.01 · states quantitative result 0.07 · compares with prior results 0.61 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

This thesis investigates B-meson lifetimes as probes of Standard Model (SM) dynamics and physics beyond the SM (BSM), employing the Heavy Quark Expansion (HQE) and light-cone sum rules (LCSR). Within the HQE, we calculate at leading order in QCD the complete dimension-seven two-quark contributions to the CKM-favoured non-leptonic transitions $b\to c\bar{u}d$ and $b\to c\bar{c}s$, providing analytical Wilson coefficients for the $1/m_b^4$ corrections. We then extend the dimension-six Darwin contribution to a model-independent BSM framework, deriving the Wilson coefficients through order $1/m_b^3$ for a general non-leptonic effective Hamiltonian. We also determine the corresponding dimension-six four-quark weak annihilation contributions. As a special case, our results provide previously missing dimension-five and dimension-six contributions induced by SM QCD-penguin operators. Finally, we investigate B-mesogenesis, which connects the cosmic matter-antimatter asymmetry and dark matter to exotic B-meson decays. We study inclusive decay rates and lifetime ratios within the HQE and exclusive $B^+\to p\psi$ decays using LCSR. Comparisons with experimental constraints from BaBar, Belle and Belle II restrict the allowed parameter space. We also identify kinematic regions where power-suppressed contributions exceed the leading terms, highlighting limitations of the HQE. Together, these studies advance the theoretical understanding of heavy-hadron lifetimes, strengthen the bridge between precision flavour physics and physics beyond the SM, and open new avenues for probing the interplay between heavy-quark dynamics and the dark sector.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 This thesis investigates B-meson lifetimes as probes of Standard Model (SM) dynamics and physics beyond the SM (BSM), employing the Heavy Quark Expansion (HQE) and light-cone sum rules (LCSR). contribution 0.91 0.87 0.06 asserted 0.98
s1 Within the HQE, we calculate at leading order in QCD the complete dimension-seven two-quark contributions to the CKM-favoured non-leptonic transitions $b\to c\bar{u}d$ and $b\to c\bar{c}s$, providing analytical Wilson coefficients for the $1/m_b^4$ corrections. contribution 0.70 0.96 0.04 asserted 1.00
s2 We then extend the dimension-six Darwin contribution to a model-independent BSM framework, deriving the Wilson coefficients through order $1/m_b^3$ for a general non-leptonic effective Hamiltonian. contribution 0.86 0.96 0.04 asserted 1.00
s3 We also determine the corresponding dimension-six four-quark weak annihilation contributions. contribution 0.83 0.94 0.02 asserted 1.00
s4 As a special case, our results provide previously missing dimension-five and dimension-six contributions induced by SM QCD-penguin operators. result 0.62 0.94 0.04 asserted 1.00
s5 Finally, we investigate B-mesogenesis, which connects the cosmic matter-antimatter asymmetry and dark matter to exotic B-meson decays. contribution 0.98 0.80 0.04 asserted 0.99
s6 We study inclusive decay rates and lifetime ratios within the HQE and exclusive $B^+\to p\psi$ decays using LCSR. contribution 0.91 0.93 0.03 asserted 0.99
s7 Comparisons with experimental constraints from BaBar, Belle and Belle II restrict the allowed parameter space. result 0.53 0.54 0.06 asserted 0.98
s8 We also identify kinematic regions where power-suppressed contributions exceed the leading terms, highlighting limitations of the HQE. limitation 0.79 0.94 0.06 asserted 1.00
s9 Together, these studies advance the theoretical understanding of heavy-hadron lifetimes, strengthen the bridge between precision flavour physics and physics beyond the SM, and open new avenues for probing the interplay between heavy-quark dynamics and the dark sector. interpretation 0.99 0.48 0.82 asserted 0.99

What kind of paper the classifier reports this is: theoretical result 1.00 · evidence from proof or derivation 1.00.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. 1: Illustration of the construction of the effective weak Hamiltonian for the transition b → cud¯ . At energies well below the electroweak scale, the W boson is integrated out, replacing the full SM interaction by a local four-fermion interaction. description of possible BSM effects by parametrizing short-distance physics in terms of higher-dimensional operators and their corresponding Wilson coefficients, without requiring knowledge of the underlying ultraviolet (UV) completion. This framework is the foundational first step for all subsequent calculations of weak decay amplitudes in…
Figure 2. 2: Diagrams for the mixing between two-quark and four-quark dimension￾seven operators in the HQE. (a) Single gluon emission from a light quark propagator, corresponding to the D2G term. (b) Double gluon emission from a light quark propagator, corresponding to the G2 term. HQE operators. The corresponding operators are R q 0 = 2 m2 b ¯biγ µ γ5D⃗ α bi q¯jγµPLD⃗ αqj , Rq 1 = 4 m2 b ¯biγ µPLD⃗ α bi q¯jγµPLD⃗ αqj , R q 2 = 4 m2 b ¯biγ µPLD⃗ ν bi q¯jγνPLD⃗ µqj , Rq 3 = 4mq mb ¯biPLbi q¯jPLqj , (2.15) where q = u, d, s. The corresponding colour-rearranged operators, denoted by Req i , are…
Figure 3. 1: Diagrammatic representation of the ∆B = 0 four-quark operator contributions in the HQE for the transition b → q1q¯2q3: weak exchange (WE), Pauli interference (PI), and weak annihilation (WA). terms of the form log(m2 q /m2 b ) in the matching coefficients. The appearance of these IR logarithms reflects the mixing of the dimension-six two-quark operators into the ∆B = 0 dimension-six four-quark operators under renormalisation. To obtain IR-finite Wilson coefficients, we explicitly compute the corresponding one-loop renormalisation of the four-quark operators and combine it with the…
Figure 4. 1: Complete set of four-quark topologies (see Eq. (4.10)) induced by the Mesogenesis operators in Eq. (4.1). The internal fermions f1 and f2 are generic and may correspond to any of the particles appearing in the Mesogenesis operators, namely ψ, u, d, s, or c. Eq. (4.2) into Eq. (1.13), the dimension-six four-quark operators contribution to the total decay rate of topology-IV reads Γ (4q) (6,d),IV (B) = − |G(d) | 2 2mB Im Z d 4x ⟨B|i T IV (d) (x)|B⟩ + (x ↔ 0), (4.11) where we define for convenience T IV (d) (x) = ϵijk ϵmnr T n u¯ i R(x) b c,j R (x) ψ¯(x) d c,k R (x) ¯b c,m R u n R ¯d…

Figures reproduced from arXiv:2610.25311 by the authors.

References

Discussion

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