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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). A study of CP violation in the decays B± → [K+ K- π+π-]Dh± (h = K, π) and B± → [π+ π- π+ π-]Dh±. Eur. Phys. J. C, 83(6), 547–23pp.
Abstract: The first study of CP violation in the decay mode B-+/- -> [K+K-pi(+)pi(-)](D)h(+/-), with h = K, pi, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9fb(-1). The analysis is performed in bins of phase space, which are optimised for sensitivity to local CP asymmetries. CP-violating observables that are sensitive to the angle gamma of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for B-+/- -> [K+K-pi(+)pi(-)](D)h(+/-) and B-+/- -> [pi(+)pi(-)pi(+)pi(-)](D)h(+/-) 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). Λc+ polarimetry using the dominant hadronic mode. J. High Energy Phys., 07(7), 228–26pp.
Abstract: The polarimeter vector field for multibody decays of a spin-half baryon is introduced as a generalisation of the baryon asymmetry parameters. Using a recent amplitude analysis of the Lambda(+)(c) -> pK(-)pi(+) decay performed at the LHCb experiment, we compute the distribution of the kinematic-dependent polarimeter vector for this process in the space of Mandelstam variables to express the polarised decay rate in a model-agnostic form. The obtained representation can facilitate polarisation measurements of the Lambda(+)(c) baryon and eases inclusion of the Lambda(+)(c)-> pK(-)pi(+) decay mode in hadronic amplitude analyses.
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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). Evidence of a J / ψK0S Structure in B0 → J / ψφK0S Decays. Phys. Rev. Lett., 131(13), 131901–11pp.
Abstract: An amplitude analysis of B0 -> J=psi phi K0S decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 9 fb-1, collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. Evidence with a significance of 4.0 standard deviations of a structure in the J=psi K0S system, named T theta psi s1o4000 thorn 0, is seen, with its mass and width measured to be 3991 thorn 12 thorn 9 -10 -17 MeV=c2 and 105 thorn 29 thorn 17 -25 -23 MeV, respectively, where the first uncertainty is statistical and the second systematic. The T theta psi s1 o4000 thorn 0 state is likely to be the isospin partner of the T theta psi s1 o4000 thorn thorn state, previously observed in the J=psi K thorn system of the B thorn -> J=psi phi K thorn decay. When isospin symmetry for the charged and neutral T theta psi s1 o4000 thorn states is assumed, the signal significance increases to 5.4 standard deviations.
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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 Υ production in pp collisions at √s=5 TeV. J. High Energy Phys., 07(7), 069–33pp.
Abstract: The production cross-sections of Υ mesons, namely Υ(1S), Υ(2S) and Υ(3S), in pp collisions at root s = 5TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 +/- 0.18 pb(-1) collected by the LHCb detector. The Υ mesons are reconstructed in the decay mode Υ -> mu(+)mu(-). Double differential cross-sections times branching fractions, as functions of the transverse momentum p(T) and the rapidity y of the Υ mesons, are measured in the range pT < 20 GeV/ c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are sigma((sic)(1S)) x B((sic)(1S) -> mu(+) mu(-)) = 2101 +/- 33 +/- 83 pb, sigma((sic)(2S)) x B((sic)(2S) -> mu(+) mu(-)) = 526 +/- 20 +/- 21 pb, sigma((sic)(3S)) x B((sic)(3S) -> mu(+) mu(-)) = 242 +/- 16 +/- 10 pb, where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different (sic) states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of (sic)(1S) at root s = 5TeV is updated as well using the directly measured cross-section results from this analysis.
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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 and branching fraction measurement of the Λb0 → Ds- p decay. J. High Energy Phys., 07(7), 075–23pp.
Abstract: The first observation of the Lambda(0)(b) -> D-s(-) p decay is presented using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of root s = 13TeV, corresponding to a total integrated luminosity of 6 fb(-1). Using the Lambda(0)(b) -> Lambda(+pi-)(c) decay as the normalisation mode, the branching fraction of the Lambda(0)(b) -> D-s(-) p decay is measured to be B (Lambda(0)(b) -> D-s(-) p) = (12.6 +/- 0.5 +/- 0.3 +/- 1.2) x 10(-6), where the first uncertainty is statistical, the second systematic and the third due to uncertainties in the branching fractions of the Lambda(0)(b) -> Lambda(+pi-)(c), D-s(-) -> K-K+pi(-) and Lambda(+)(c) -> pK(-)pi(+) decays.
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