LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Observation of the suppressed decay Lambda(0)(b) -> p pi(-) mu(+) mu(-). J. High Energy Phys., 04(4), 029–16pp.
Abstract: The suppressed decay Lambda(0)(b) -> p pi(-) mu(+) mu(-), excluding the J/psi and psi(2S) -> mu(+) mu(-) resonances, is observed for the first time with a significance of 5.5 standard deviations. The analysis is performed with proton- proton collision data corresponding to an integrated luminosity of 3 fb(-1) collected with the LHCb experiment. The Lambda(0)(b) -> p pi(-) mu(+) mu(-) branching fraction is measured relative to the Lambda(0)(b) -> J/psi (-> mu(+) mu(-)) p pi(-) branching fraction giving B (Lambda(0)(b) -> p pi(-) mu(+) mu(-))/B(Lambda(0)(b) -> J/psi (-> mu(+) mu(-)) p pi(-)) = 0.044 +/- 0.012 +/- 0.007, where the first uncertainty is statistical and the second is systematic. This is the first observation of a b -> d transition in a baryonic decay.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Searches for rare B-s(0) and B-0 decays into four muons. J. High Energy Phys., 03(3), 109–27pp.
Abstract: Searches for rare B-s(0) and B-0 decays into four muons are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1). Direct decays and decays via light scalar and J/psi resonances are considered. No evidence for the six decays searched for is found and upper limits at the 95% confidence level on their branching fractions ranging between 1.8 x 10(-10) and 2.6 x 10(-9) are set.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Test of lepton universality with Lambda(0)(b) -> pK(-) l(+)l(-). J. High Energy Phys., 05(5), 40–27pp.
Abstract: The ratio of branching fractions of the decays -> pK(-)mu(+)mu(-),RpK-1}, is measured for the first time using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb(-1) recorded with the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV. In the dilepton mass-squared range 0.1 < q(2)< 6.0 GeV2/c(4) and the pK(-) mass range m(pK(-)) < 2600 MeV/c(2), the ratio of branching fractions is measured to be RpK-1=1.17-0.16+0.18 +/- 0.0$$ {R}{pK}<^>{-1}={1.17}{-0.16}<^>{+0.18}\pm 0.07 $$\end{document}, where the first uncertainty is statistical and the second systematic. This is the first test of lepton universality with b baryons and the first observation of the decay -> pK(-)e(+)e(-).
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Observation of Lambda b(0) -> D(+)p pi(-)pi(-) and Lambda b(0) -> D-*+p pi(-)pi(-) decays. J. High Energy Phys., 03(3), 153–30pp.
Abstract: The multihadron decays Lambda(0)(b) -> D(+)p pi(-)pi(-) and Lambda(0 )(b)-> D-*+p pi(-)pi(-) are observed in data corresponding to an integrated luminosity of 3fb(-1), collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay Lambda(0)(b) -> Lambda(+)(c)pi(+)pi(-)pi(-) as a normalisation channel, the ratio of branching fractions is measured to be B(Lambda(0)(b) -> D(+)p pi(-)pi(-))/B(Lambda(0)(b) -> Lambda(+)(c)pi(+)pi(-)pi(-)) x B(D+ -> K-pi(+)pi(+))/B(Lambda(+)(c)-> pK(-)pi(+)) = (5.35 +/- 0.21 +/- 0.16) %, where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the Lambda(0)(b)-> D-*+p pi(-)pi(-) and Lambda(0)(b) -> D(+)p pi(-)pi(-) decays is found to be B(Lambda(0)(b)-> D-*+p pi(-)pi(-))/B(Lambda(0)(b) -> D(+)p pi(-)pi(-)) x (B(D-*+-> D+pi(0)) + B(D (*)+-> D- (+)gamma)) = (61.3 +/- 4.3 +/- 4.0) %.
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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 ratio of branching fractions B(B+c → B0sπ+)/B(B+c → J/ψπ+). J. High Energy Phys., 07(7), 066–19pp.
Abstract: The ratio of branching fractions of B-c(+) -> B-s(0)pi(+) and B-c(+) -> J/psi pi(+) decays is measured with proton-proton collision data of a centre-of-mass energy of 13TeV. The data were collected with the LHCb experiment during 2016-2018, corresponding to an integrated luminosity of 5.4 fb(-1). The B-s(0) mesons are reconstructed via the decays B-s(0) -> J/psi phi and B-s(0) -> D-s(-)pi(+). The ratio of branching fractions is measured to be B(B-c(+) -> B-s(0)pi(+))/B(B-c(+) -> J/psi pi(+)) = 91 +/- 10 +/- 8 +/- 3 where the first uncertainty is statistical, the second is systematic and the third is due to the knowledge of the branching fractions of the intermediate state decays.
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