Abstract
We study the inclusive Hb → Xsγ decay with Hb a beauty baryon, in particular Λb, employing an expansion in the heavy quark mass at \( \mathcal{O}\left({m}_b^{-3}\right) \) at leading order in αs, keeping the dependence on the hadron spin. For a polarized baryon we compute the distribution \( \frac{d^2\Gamma}{dy\ d\cos {\theta}_P} \), with y = 2Eγ/mb, Eγ the photon energy and θP the angle between the baryon spin vector and the photon momentum in the Hb rest-frame. We discuss the correlation between the baryon and photon polarization, and show that effects of physics beyond the Standard Model can modify the photon polarization asymmetry. We also discuss a method to treat the singular terms in the photon energy spectrum obtained by the OPE.
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Acknowledgments
We thank Andrzej J. Buras and Gil Paz for discussions. This research has been carried out within the INFN project (Iniziativa Specifica) QFT-HEP.
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Colangelo, P., De Fazio, F. & Loparco, F. On the decay mode Λb → Xsγ. J. High Energ. Phys. 2023, 147 (2023). https://doi.org/10.1007/JHEP10(2023)147
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DOI: https://doi.org/10.1007/JHEP10(2023)147