Study of the $$\Lambda _{b} \rightarrow N^*\ell ^+ \ell ^- $$ decay in light cone sum rules

In a covariant quark-diquark model, we investigate the rare decay of Λ b → nl + l − and Λ b → nγ in the Bethe-Salpeter equation approach. In this model the baryons are treated as bound states of a constituent quark and a diquark interacting via a gluon exchange and the linear confinement. We find that the ratio of form factors R is varies from −0.90 to −0.25 and the branching ratios Br(Λ b → nl + l − ) × 10 8 are 6.79(l = e), 4.08 (l = µ), 2.9 (l = τ ) and the branching ratio Br(Λ b → γ) × 10 7 ) = 3.69 in central values of parameters.

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FCNC transitions of $$\Lambda _b$$ to neutron in Bethe–Salpeter equation approach

Liu

Wang

Kang

et al. 2020

Eur. Phys. J. C

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$$\Lambda _b\rightarrow p$$ transition form factors in perturbative QCD

Han

et al. 2022

Eur. Phys. J. C

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We reanalyze the $$\Lambda _b\rightarrow p$$ Λ b → p transition form factors in the perturbative QCD (PQCD) approach by including higher-twist light-cone distribution amplitudes (LCDAs) of a $$\Lambda _b$$ Λ b baryon and a proton. The previous PQCD evaluation performed decades ago with only the leading-twist $$\Lambda _b$$ Λ b baryon and proton LCDAs gave the form factors, which are two orders of magnitude smaller than indicated by experimental data. We find that the twist-4 $$\Lambda _b$$ Λ b baryon LCDAs and the twist-4 and -5 proton LCDAs contribute dominantly, and the enhanced form factors become consistent with those from lattice QCD and other nonperturbative methods. The estimated branching ratios of the semileptonic decays $$\Lambda _b\rightarrow p\ell {\bar{\nu }}_\ell $$ Λ b → p ℓ ν ¯ ℓ and the hadronic decay $$\Lambda _b\rightarrow p\pi $$ Λ b → p π are also close to the data. It implies that the b quark mass is not really heavy enough, and higher-power contributions play a crucial role, similar to the observation made in analyses of B meson transition form factors. With the formalism established in this work, we are ready to study various exclusive heavy baryon decays systematically in the PQCD approach.

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$$\Lambda _b \rightarrow p, N^*(1535)$$ form factors from QCD light-cone sum rules

et al. 2023

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In this work, we calculate the transition form factors of $$\Lambda _b$$ Λ b decaying into proton and $$N^*(1535)$$ N ∗ ( 1535 ) ($$J^P={1/2}^+$$ J P = 1 / 2 + and $${1/2}^-$$ 1 / 2 - respectively) within the framework of light-cone sum rules with the distribution amplitudes (DAs) of $$\Lambda _b$$ Λ b -baryon. In the hadronic representation of the correlation function, we have isolated both the proton and the $$N^*(1535)$$ N ∗ ( 1535 ) states so that the $$\Lambda _b \rightarrow p, N^*(1535)$$ Λ b → p , N ∗ ( 1535 ) form factors can be evaluated simultaneously. Due to the less known properties of the baryons, we investigate three interpolating currents of the light baryons and five parametrization models for DAs of $$\Lambda _b $$ Λ b . Numerically, our predictions on the $$\Lambda _b \rightarrow p$$ Λ b → p form factors and the branching fractions of $$\Lambda _b\rightarrow p\ell \nu $$ Λ b → p ℓ ν from the Ioffe or the tensor currents are consistent with the Lattice simulation and the results from the light-baryon sum rules, as well as the experimental data of $$Br(\Lambda _b^0\rightarrow p\mu ^-{{\bar{\nu }}})$$ B r ( Λ b 0 → p μ - ν ¯ ) . The predictions on the form factors of $$\Lambda _b \rightarrow N^*(1535)$$ Λ b → N ∗ ( 1535 ) are very sensitive to the choice of the interpolating currents so that the relevant measurement could be helpful to clarify the properties of baryons.

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Study of the $$\Lambda _{b} \rightarrow N^*\ell ^+ \ell ^- $$ decay in light cone sum rules

Cited by 3 publications

References 18 publications

FCNC transitions of $$\Lambda _b$$ to neutron in Bethe–Salpeter equation approach

FCNC transitions of $$\Lambda _b$$ to neutron in Bethe–Salpeter equation approach

$$\Lambda _b\rightarrow p$$ transition form factors in perturbative QCD

$$\Lambda _b \rightarrow p, N^*(1535)$$ form factors from QCD light-cone sum rules

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