A natural interpretation on the data of $Λ_c\toΣπ$

Ke, Hong-Wei; Li, Xue-Qian

doi:10.48550/arxiv.2008.12163

“…However, the inner W -emission diagram was evaluated directly in the quark model rather than through the pole model. It has been demonstrated recently in [221] that the long-distance effect through the weak decay Λ + c → Λρ followed by the final-state rescattering of Λρ → Σπ will contribute destructively to the amplitude of Λ + c → Σπ and flip the sign of α obtained in the old pole model calculation in [155]. However, it is clear by now that the pole model alone should be able to explain the data.…”

Section: E Pole Model Versus Current Algebramentioning

confidence: 93%

“…In general, nonfactorizable decay amplitudes do receive contributions from long-distance final-state rescattering. Indeed, nonfactorizable contributions modelled as final-state interactions through the one-particle-exchange process have been applied to singly and doubly charmed baryon decays [118,216,218,220,221].…”

Section: E Pole Model Versus Current Algebramentioning

confidence: 99%

Charmed Baryon Physics Circa 2021

Cheng¹

2021

Preprint

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Contents I. Introduction II. Spectroscopy A. Singly charmed baryons 1. Λ c states 2. Ξ c states 3. Ω c states 4. Ξ ′ c states 5. Σ c states 6. Regge trajectories 7. Antitriplet and sextet states B. Doubly charmed baryons III. Lifetimes A. Singly charmed baryons 1. Lifetime measurements 2. Heavy quark expansion B. Doubly charmed baryons IV. Hadronic weak decays A. Nonleptonic decays of singly charmed baryons B. Discussions 1. Λ + c decays 2. Ξ 0 c and Ξ + c decays 3. Ω 0 c decays C. Charm-flavor-conserving nonleptonic decays D. Nonleptonic decays of doubly charmed baryons E. Pole model versus current algebra F. Semileptonic decays V. Electromagnetic and weak radiative decays A. Electromagnetic decays B. Weak radiative decays VI. CP violation VII. Conclusions VIII. Acknowledgments References 2 I. INTRODUCTION Charm baryon spectroscopy provides an excellent ground for studying the dynamics of light quarks in the environment of a heavy quark or two heavy quarks. In the past two decades, many new excited charmed baryon states have been discovered by BaBar, Belle, CLEO and LHCb. Both B decays and the e + e − → cc continuum provide very rich sources of charmed baryons. Many efforts have been made to identify the quantum numbers of these new states and understand their properties. In 2017 LHCb has explored the charmed baryon sector of the Ω c and observed five narrow excited Ω c states [1]. In 2020 LHCb has announced the observation of three new Ξ c excited states in the Λ + c K − spectrum [2]. Both have triggered a flood of interest in attempting to identify their spin-parity quantum numbers. In 2017 LHCb observed a new resonance in the Λ + c K − π + π + mass spectrum with a mass of 3621.40 ± 0.78 MeV [3], which was consistent with expectations for the doubly charmed baryon Ξ ++ cc baryon and significantly larger than the mass of 3519 MeV measured by SELEX for Ξ + cc [4]. This opens a new chapter on doubly heavy baryons. Lifetimes of the heavy baryons are commonly analyzed within the framework of heavy quark expansion (HQE). In this approach, the predicted lifetime pattern for charmed baryons, namely,), is in agreement with experiments listed in the 2018 version of the Particle Data Group (PDG) [5]. This lifetime hierarchy in which the Ω c is shortest-lived among the four charmed baryons owing to its large constructive Pauli interference has been known to the community for a long time. However, in 2018 LHCb has reported a new measurement of the Ω 0 c lifetime [6], which is nearly four times larger than the current world-average value of τ (Ω 0 c ) inferred from fixed target experiments. This indicates that the Ω 0 c , which is naively expected to be shortest-lived in the charmed baryon system, now lives longer than the Λ + c . The observation of a huge jump of the Ω 0 c lifetime is beyond imagination. This very striking experimental result calls for a better theoretical understanding of charmed baryon lifetimes based on the HQE. After the first observation of the Ξ ++ cc , LHCb has presented the first lifetime measureme...

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“…As the final state interaction, the triangle rescattering process has been well applied to [12,13]. Likewise, we propose the rescattering Λ + c → Σ * + η → Λa + 0 decay, as seen in Fig.…”

Section: Formalismmentioning

confidence: 76%

“…The cutoff parameter c Λ is not well controlled. The estimation presents that c Λ = λΛ QCD + m π , where Λ QCD = 0.22 GeV, and λ is a free parameter [13,18,21]. On the other hand, c Λ can be taken as an empirical parameter, determined by the data.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

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Cabibbo-favored $Λ^+_c\toΛa_{0}(980)^+$ decay in the final state interaction

Yu,

Hsiao

2020

Preprint

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The anti-triplet charmed baryon decays with the light scalar mesons are rarely measured, whereas the recent observation of the Cabibbo-favored Λ + c → Ληπ + decay hints a possible Λ + c → Λa 0 (980) + , a 0 (980) + → ηπ + process. We hence study the Λ + c → Λa 0 (980) + decay. Particularly, it is found that the final state interaction can give a significant contribution, where Σ + (1385)and η in Λ + c → Σ + (1385)η by exchanging a charged pion are transformed as Λ and a 0 (980) + , respectively. Accordingly, we predict B(Λ + c → Λa 0 (980) + ) = (1.7 +2.8 −1.0 ± 0.3) × 10 −3 , accessible to the BESIII, BELLEII and LHCb experiments.

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Equivalent SU(3)f approaches for two-body anti-triplet charmed baryon decays

Hsiao

¹

,

Wang

²

,

Zhao

³

2022

J. High Energ. Phys.

12

0

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For the two-body Bc → BM decays, where Bc denotes the anti-triplet charm baryon and B(M) the octet baryon (meson), there exist two theoretical studies based on the SU(3) flavor [SU(3)f] symmetry. One is the irreducible SU(3)f approach (IRA). In the irreducible SU(3)f representation, the effective Hamiltonian related to the initial and final states forms the amplitudes for Bc → BM. The other is the topological-diagram approach (TDA), where the W-boson emission and W-boson exchange topologies are drawn and parameterized for the decays. As required by the group theoretical consideration, we present the same number of the IRA and TDA amplitudes. We can hence relate the two kinds of the amplitudes, and demonstrate the equivalence of the two SU(3)f approaches. We find a specific W-boson exchange topology only contributing to $$ {\Xi}_c^0 $$ Ξ c 0 →BM. Denoted by EM, it plays a key role in explaining $$ \mathcal{B} $$ B ($$ {\Xi}_c^0 $$ Ξ c 0 → Λ0$$ {K}_S^0 $$ K S 0 , Σ0$$ {K}_S^0 $$ K S 0 , Σ+K−). We consider that $$ {\Lambda}_c^{+} $$ Λ c + → nπ+ and $$ {\Lambda}_c^{+} $$ Λ c + → pπ0 proceed through the constructive and destructive interfering effects, respectively, which leads to $$ \mathcal{B} $$ B ($$ {\Lambda}_c^{+} $$ Λ c + → nπ+) » $$ \mathcal{B} $$ B ($$ {\Lambda}_c^{+} $$ Λ c + → pπ0) in agreement with the data. With the exact and broken SU(3)f symmetries, we predict the branching fractions of Bc→BM to be tested by future measurements.

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A natural interpretation on the data of $Λ_c\toΣπ$

Cited by 3 publications

References 21 publications

Charmed Baryon Physics Circa 2021

Charmed Baryon Physics Circa 2021

Cabibbo-favored $Λ^+_c\toΛa_{0}(980)^+$ decay in the final state interaction

Equivalent SU(3)f approaches for two-body anti-triplet charmed baryon decays

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