The first search for the Bs0→K-π+γ decay in the range 796<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<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<1800 MeV/c2, the ratio R=(0.2±2.7±1.3)×10-2 is measured.

Aaij, R., Abdelmotteleb, A., Abellan Beteta, C., Abudinen, F., Ackernley, T., Adefisoye, A., et al. (2026). First Evidence of the Bs0 →k-π+γ Decay. PHYSICAL REVIEW LETTERS, 136(17) [10.1103/g8fs-djyt].

First Evidence of the Bs0 →k-π+γ Decay

Anelli A.;Borsato M.;Calvi M.;Capelli S.;Carniti P.;Falcao L. N.;Fazzini D.;Gotti C.;Kirsebom V. S.;Malentacca L.;Martinazzoli L.;Martinelli M.;Minotti A.;Pizzichemi M.;Salomoni M.;
2026

Abstract

The first search for the Bs0→K-π+γ decay in the range 796<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<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<1800 MeV/c2, the ratio R=(0.2±2.7±1.3)×10-2 is measured.
Articolo in rivista - Articolo scientifico
Astrophysics; Decay (organic); Tellurium compounds; Vanadium compounds
English
30-apr-2026
2026
136
17
171801
none
Aaij, R., Abdelmotteleb, A., Abellan Beteta, C., Abudinen, F., Ackernley, T., Adefisoye, A., et al. (2026). First Evidence of the Bs0 →k-π+γ Decay. PHYSICAL REVIEW LETTERS, 136(17) [10.1103/g8fs-djyt].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/609682
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