LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Search for CP violation in D(s)+ → K- K+ K+ decays. J. High Energy Phys., 07(7), 067–25pp.
Abstract: A search for direct CP violation in the Cabibbo-suppressed decay D-s(+) -> K-K+ K+ and in the doubly Cabibbo-suppressed decay D+ -> K- K+ K+ is reported. The analysis is performed with data collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of 13TeV corresponding to an integrated luminosity of 5.6 fb(-1). The search is conducted by comparing the D-(s)(+) and D-(s)(-) Dalitz-plot distributions through a model-independent binned technique, based on fits to the K-K+K+ invariantmass distributions, with a total of 0.97 (1.27) million D-s(+) (D+) signal candidates. The results are given as p-values for the hypothesis of CP conservation and are found to be 13.3% for the D+ -> K-K+ K+ decay and 31.6% for the D+ -> K-K+ K+ decay. No evidence for CP violation is observed in these decays.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Observation and branching fraction measurement of the decay Ξb- → Λ0 bπ-. Phys. Rev. D, 108(7), 072002–16pp.
Abstract: The decay E-b -> A0bx-- is observed using a proton-proton collision data sample collected at center-of-ffiffimass energy p s 1/4 13 TeV with the LHCb detector, corresponding to an integrated luminosity of 5.5 fb-1. This process is mediated by the s -> uu over bar d quark-level transition, where the b quark in the E-b baryon is a spectator in the decay. Averaging the results obtained using the two A0b decay modes, A0b -> A thorn c x-- and A0b -> A thorn c x--x- thorn x--, the relative production ratio is measured to be ofE-b =fA0b thorn BoE-b -> A0bx-- thorn 1/4 o7.3 ⠂ 0.8 ⠂ 0.6 thorn x 10-4. Here the uncertainties are statistical and systematic, respectively, and fE-bofA0b thorn is the fragmentation fraction for a b quark into a E-b (A0b) baryon. Using an independent measurement of fE-b =fA0b, the branching fraction BoE-b -> A0bx-- thorn 1/4 o0.89 ⠂ 0.10 ⠂ 0.07 ⠂ 0.29 thorn % is obtained, where the last uncertainty is due to the assumed SU(3) flavor symmetry in the determination of fE-b =fA0b.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Associated production of prompt J/ψ and Υ mesons in pp collisions at √s=13 TeV. J. High Energy Phys., 08(8), 093–24pp.
Abstract: The associated production of prompt J/psi and Υ mesons in pp collisions at a centre-of-mass energy of root s = 13T eV is studied using LHCb data, corresponding to an integrated luminosity of 4 fb(-1). The measurement is performed for J/psi (Υ) mesons with a transverse momentum pT < 10 (30) GeV/ c in the rapidity range 2.0 < y < 4.5. In this kinematic range, the cross-section of the associated production of prompt J/psi and Υ(1S) mesons is measured to be 133 +/- 22 +/- 7 +/- 3 pb, with a significance of 7.9 s, and that of prompt J/psi and Υ(2S) mesons to be 76 +/- 21 +/- 4 +/- 7 pb, with a significance of 4.9 sigma. The first uncertainty is statistical, the second systematic, and the third due to uncertainties on the used branching fractions. This is the first observation of the associated production of J/psi and Υ(1S) in proton-proton collisions. Differential cross-sections are measured as functions of variables that are sensitive to kinematic correlations between the J/psi and Υ(1S) mesons. The effective cross-sections of the associated production of prompt J/psi and Υ mesons are obtained and found to be compatible with measurements using other particle productions.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Observation of the B+ → Jψη'K+ decay. J. High Energy Phys., 08(8), 174–27pp.
Abstract: The B+ -> J psi eta'K+ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8, and 13TeV, corresponding to a total integrated luminosity of 9 fb(-1). The branching fraction of this decay is measured relative to the known branching fraction of the B+ -> psi(2S)K+ decay and found to be B(B+ -> J psi eta'K+)/B(B+ -> psi(2S)K+) = (4.91 +/- 0.47 +/- 0.29 +/- 0.07) x 10(-2), where the first uncertainty is statistical, the second is systematic and the third is related to external branching fractions. A first look at the J/psi eta' mass distribution is performed and no signal of intermediate resonances is observed.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2024). Observation of Cabibbo-Suppressed Two-Body Hadronic Decays and Precision Mass Measurement of the Ω0c Baryon. Phys. Rev. Lett., 132(8), 081802–11pp.
Abstract: The first observation of the singly Cabibbo-suppressed 0c -> -K thorn and 0c -> -z thorn decays is reported, using proton -proton collision data at a center -of -mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb-1, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be Bo0c ->-K thorn thorn Bo0c ->-z thorn thorn 1/4 1/26.08 ⠂ 0.51ostat thorn ⠂ 0.40osyst thorn ⠃%; Bo0c ->-z thorn thorn Bo0c ->-z thorn thorn 1/4 1/215.81 ⠂ 0.87ostat thorn ⠂ 0.44osyst thorn ⠂ 0.16oext thorn ⠃%. In addition, using the 0c -> -z thorn decay channel, the 0c baryon mass is measured to be Mo0c thorn 1/4 2695.28 ⠂ 0.07ostat thorn ⠂ 0.27osyst thorn ⠂ 0.30oext thorn MeV; improving the precision of the previous world average by a factor of 4.
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