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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Lucio Martinez, M., et al. (2026). First evidence of violation in beauty baryon to charmonium decays. Sci. Bull., 71(3), 547–557.
Abstract: A study of the difference in the CP asymmetries between Lambda(0)(b) -> J/psi p pi(-) and Lambda(0)(b) -> J/psi pK(-)decays, Delta A(CP), is performed using proton-proton collision data collected by the LHCb experiment in the years 2015-2018, corresponding to an integrated luminosity of 6fb(-1). This quantity is measured to be Delta A(CP) = (4.03 +/- 1.18 +/- 0.23)%, where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of Delta A(CP) = (4.31 +/- 1.06 +/- 0.28)% is obtained, corresponding to a significance of 3.9 sigma against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2025). Study of Ds1(2460)+ → Ds+ π+π- in B → (D)over-bar(*)Ds+π+π- decays. Sci. Bull., 70(9), 1432–1444.
Abstract: An amplitude analysis of the D-s1(2460)(+) -> D-s(+)pi(+)pi(-) transition is performed simultaneously in B-0 -> D-Ds+pi(+)pi(-), B+ -> (D) over bar D-0(s)+pi(+)pi(-), and B-0 -> D*D--(s)+pi(+)pi(-) decays. The study is based on a data sample of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of root s = 7,8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb(-1). A clear double-peak structure is observed in the m(pi(+)pi(-)) spectrum of the D-s1(2460)(+) -> D-s(+)pi(+)pi(-) decay. The data can be described either with a model including f(0)(500), f(0)(980), and f(2)(1270) resonances, in which the contributions of f(0)(980) and f(2)(1270) are unexpectedly large, or with a model including f(0)(500), a doubly charged open-charm tetraquark state T-c (s) over bar(++) and its isospin partner T-c (s) over bar(0). If the former is considered implausible, the T-c (s) over bar states are observed with high significance, and the data are consistent with isospin symmetry. When imposing isospin constraints between the two T-c (s) over bar states, their mass and width are determined to be (2327 +/- 13 +/- 13) MeV and (96 +/- 16(-23)(+170)) MeV, respectively, where the first uncertainty is statistical and the second is systematic. The mass is slightly below the DK threshold, and a spin-parity of 0(+) is favoured with high significance. (c) 2025 The Authors. Published by Elsevier B.V. and Science China Press.
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