LHCb CollaborationAaij, R.Adeva Andany, BernardoÁlvarez Cartelle, PaulaDosil Suárez, ÁlvaroFernández Albor, VíctorGallas Torreira, AbrahamHernando Morata, José ÁngelPazos Álvarez, AntonioPérez Trigo, EliseoPló Casasús, MáximoRodriguez Perez, P.Romero Vidal, AntonioSaborido Silva, Juan JoséSanmartín Sedes, BraisSantamarina Ríos, CibránSeco, M.Vázquez Regueiro, Pablo2026-01-122026-01-122013-11-12The LHCb collaboration., Aaij, R., Abellan Beteta, C. et al. First observation of the decay B0s → φK∗0 . J. High Energ. Phys. 2013, 92 (2013). https://doi.org/10.1007/JHEP11(2013)092https://hdl.handle.net/10347/45018The first observation of the decay B0s → φK∗0 is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb−1 of pp collisions at √s = 7 TeV, collected with the LHCb detector. A yield of 30 ± 6 B0s → (K+K−)(K−π+) decays is found in the mass windows 1012.5 < M(K+K−) < 1026.5 MeV/c2 and 746 < M(K−π+) < 1046 MeV/c2. The signal yield is found to be dominated by B0s → φK∗0 decays, and the corresponding branching fraction is measured to be B(B0s → φK∗0)= (1.10 ± 0.24 (stat) ± 0.14 (syst) ± 0.08 (fd/fs)) × 10−6, where the uncertainties are statistical, systematic and from the ratio of fragmentation fractions fd/fs which accounts for the different production rate of B0 and B0s mesons. The significance of B0s → φK∗0 signal is 6.1 standard deviations. The fraction of longitudinal polarization in B0s → φK∗0 decays is found to be f0 = 0.51 ± 0.15 (stat) ± 0.07 (syst)eng© 2026 Springer Nature. This article is distributed under the terms of the Creative Commons Attribution 2.0 International LicenseAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/B physicsFlavour Changing Neutral CurrentsFlavor physicsHadron-Hadron Scatteringjournal article10.1007/JHEP11(2013)0921029-8479open access