First Evidence of the Bs0K- π+γ Decay



Aaij, R, Abdelmotteleb, ASW, Beteta, C Abellan, Abudinen, F, Ackernley, T, Adefisoye, AA, Adeva, B, Adinolfi, M, Adlarson, P, Agapopoulou, C
et al (show 1164 more authors) (2026) First Evidence of the Bs0K- π+γ Decay PHYSICAL REVIEW LETTERS, 136 (17). 171801-. ISSN 0031-9007, 1079-7114

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Abstract

The first search for the Bs0→K-π+γ decay in the range 796<m(K-π+)<1800 MeV/c2 is performed using data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The photons are reconstructed through their conversion into an electron-positron pair, which significantly improves the mass resolution of the reconstructed decays with respect to decays with an unconverted photon. A signal excess with a significance of 3.5 standard deviations is measured, constituting the first experimental evidence for this decay. In the range 796<m(K-π+)<996 MeV/c2, the ratio R between the branching fractions of the signal decay and the favored B¯0→K-π+γ decay is measured to be R=(3.7±1.2±0.4)×10-2 where the first uncertainty is statistical and the second is systematic. This measurement is consistent with the value predicted in the Standard Model. In the range 996<m(K-π+)<1800 MeV/c2, the ratio R=(0.2±2.7±1.3)×10-2 is measured.

Item Type: Article
Uncontrolled Keywords: LHCb Collaboration
Divisions: Faculty of Humanities & Social Sciences
Faculty of Science & Engineering
Faculty of Science & Engineering > School of Physical Sciences
Faculty of Science & Engineering > School of Physical Sciences > Physics
Faculty of Humanities & Social Sciences > School of the Arts
Faculty of Humanities & Social Sciences > School of the Arts > Architecture
Depositing User: Symplectic Admin
Date Deposited: 26 May 2026 10:30
Last Modified: 12 Jun 2026 19:32
DOI: 10.1103/g8fs-djyt
Open Access URL: https://journals.aps.org/prl/pdf/10.1103/g8fs-djyt
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3198620
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