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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 New Baryons in the Ξb- π+π- and Ξb0π+π- Systems. Phys. Rev. Lett., 131(17), 171901–11pp.
Abstract: The first observation and study of two new baryonic structures in the final state Xi(0)(b)pi(+)pi(-) and the confirmation of the Xi(b)(6100)(-) state in the Xi(-)(b)pi(+)pi(-) decay mode are reported using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1). In addition, the properties of the known Xi(b)*(0), Xi(b)'(-) and Xi(b)*(-) resonances are measured with improved precision. The new decay mode of the Xi(0)(b) baryon to the Xi(+)(c) pi(-) pi(+) pi(-) final state is observed and exploited for the first time in these measurements.
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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). First Observation of a Doubly Charged Tetraquark and Its Neutral Partner. Phys. Rev. Lett., 131(4), 041902–12pp.
Abstract: A combined amplitude analysis is performed for the decays B0-+ D0D thorn s & pi;- and B thorn -+ D-D thorn s & pi; thorn , which are related by isospin symmetry. The analysis is based on data collected by the LHCb detector in proton -proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. Two new resonant states with masses of 2.908 ⠂ 0.011 ⠂ 0.020 GeV and widths of 0.136 ⠂ 0.023 ⠂ 0.013 GeV are observed, which decay to D thorn s & pi; thorn and D thorn s & pi;- respectively. The former state indicates the first observation of a doubly charged open-charm tetraquark state with minimal quark content 1/2cs over bar ud over bar ⠃, and the latter state is a neutral tetraquark composed of 1/2cs over bar u over bar d ⠃ quarks. Both states are found to have spin-parity of 0 thorn , and their resonant parameters are consistent with each other, which suggests that they belong to an isospin triplet.
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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 a Resonant Structure near the Ds+Ds- Threshold in the B+ -> Ds+Ds- K+ Decay. Phys. Rev. Lett., 131(7), 071901–12pp.
Abstract: An amplitude analysis of the B thorn & RARR; D thorn s D-s K thorn decay is carried out to study for the first time its intermediate resonant contributions, using proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. A near-threshold peaking structure, referred to as X(3960), is observed in the D thorn s D-s invariant-mass spectrum with significance greater than 12 standard deviations. The mass, width, and the quantum numbers of the structure are measured to be 3956 1 5 1 10 MeV, 43 1 13 1 8 MeV, and JPC = 0 thorn thorn , respectively, where the first uncertainties are statistical and the second systematic. The properties of the new structure are consistent with recent theoretical predictions for a state composed of cc over bar ss over bar quarks. Evidence for an additional structure is found around 4140 MeV in the D thorn s D-s invariant mass, which might be caused either by a new resonance with the 0 thorn thorn assignment or by a J=& psi;& phi; & LRARR; D thorn s D-s coupled-channel effect.
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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). Test of Lepton Universality in b → sl+l- Decays. Phys. Rev. Lett., 131(5), 051803–13pp.
Abstract: The first simultaneous test of muon-electron universality using B+ -> K(+)l(+)l(-) and B-0 -> K*(0)l(+) l(-) decays is performed, in two ranges of the dilepton invariant-mass squared, q(2). The analysis uses beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb(-1). Each of the four lepton universality measurements reported is either the first in the given q(2) interval or supersedes previous LHCb measurements. The results are compatible with the predictions of the Standard Model.
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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). Measurement of the Branching Fractions B(B0 → p(p)over-bar p(p)over-bar) and B(Bs0→ p(p)over-barp(p)over-bar). Phys. Rev. Lett., 131(9), 091901–11pp.
Abstract: Searches for the rare hadronic decays B-0 -> p (p) over barp (p) over bar and B-s(0) -> p (p) over barp (p) over bar are performed using proton-proton collision data recorded by the LHCb experiment and corresponding to an integrated luminosity of 9 fb-1. Significances of 9.3 sigma and 4.0 sigma, including statistical and systematic uncertainties, are obtained for the B-0 -> p (p) over barp (p) over bar and B-s(0) -> p (p) over barp (p) over bar signals, respectively. The branching fractions are measured relative to the topologically similar normalization decays B-0 -> J/psi(-> p (p) over bar )K*(0)(-> K+ pi(-) ) and B-s(0) -> J/psi(-> p (p) over bar )X phi(-> K+ K- ). The branching fractions are measured to be B(B-0 -> p (p) over barp (p) over bar) = (2.2 +/- 0.4 +/- 0.1 +/- 0.1) x 10(-8) and B(B-s(0) -> p (p) over barp (p) over bar) = (2.3 +/- 1.0 +/- 0.2 +/- 0.1) x 10(-8). In these measurements, the first uncertainty is statistical, the second is systematic, and the third one is due to the external branching fraction of the normalization channel.
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