Abstract
We investigate for the first time a certain class of non-factorisable contributions of the four-quark operators \( \mathcal{O} \)3−6 in the weak effective Hamiltonian to the Λb → Λℓ+ℓ− decay amplitude. We focus on the case where a virtual photon is radiated from one of the light constituents of the Λb baryon, in the kinematic situation of large hadronic recoil with an energetic Λ baryon in the final state. The effect on the suitably defined “non-local form factors” is calculated using the light-cone sum rule approach for a correlator with an interpolating current for the light Λ baryon. We find that this approach requires the introduction of new soft functions that generalise the standard light-cone distribution amplitudes (LCDAs) for the heavy Λb baryon. We give a heuristic discussion of their properties and a model that relates them to the standard LCDAs. Within this framework, we provide numerical results for the size of the non-local form factors considered.
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Acknowledgments
We thank Marzia Bordone for her contributions in the early stage of this project. This research is supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under grant 396021762 – TRR 257. The work of N.G. has been partially supported by STFC consolidated grants ST/T000694/1 and ST/X000664/1.
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Feldmann, T., Gubernari, N. Non-factorisable contributions of strong-penguin operators in Λb → Λℓ+ℓ− decays. J. High Energ. Phys. 2024, 152 (2024). https://doi.org/10.1007/JHEP03(2024)152
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DOI: https://doi.org/10.1007/JHEP03(2024)152