LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Study of B-s(0) -> J/psi pi(+)pi-K+K- decays. J. High Energy Phys., 02(2), 024–34pp.
Abstract: The decays B-s(0) -> J/psi pi(+)pi-K+K- are studied using a data set corresponding to an integrated luminosity of 9 fb(-1), collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13TeV. The decays B-s(0) -> J/psi K*(K) over bar *0 and B-s(0) -> chi(c1)(3872)K+K-, where the K+K- pair does not originate from a phi meson, are observed for the first time. Precise measurements of the ratios of branching fractions between intermediate chi(c1)(3872)phi, J/psi K*0 (K) over bar *0, psi(2S)phi and chi(c1)(3872)K+K- states are reported. A structure, denoted as X(4740), is observed in the J/psi phi mass spectrum and, assuming a Breit-Wigner parameterisation, its mass and width are determined to be m(X(4740)) = 4741 +/- 6 +/- 6 MeV/c(2), Gamma(X(4740)) = 53 +/- 15 +/- 11MeV, where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the B-s(0) meson is performed and gives a value of m(Bs)(0) = 5366.98 +/- 0.07 +/- 0.13MeV/c(2).
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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). A search for rare B → D μ+ μ- decays. J. High Energy Phys., 02(2), 032–23pp.
Abstract: A search for rare B. D mu+ mu- decays is performed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb-1. No significant signals are observed in the non-resonant mu+ mu- modes, and upper limits of B -> B0. D0 mu+ mu- < 5.1 x 10-8, B B+. D+ s mu+ mu- -> < 3.2 x 10-8, B -> B0 s. D0 mu+ mu--> < 1.6 x 10-7 and fc/fu center dot B B+ c. D+ s mu+ mu--> < 9.6 x 10-8 are set at the 95% confidence level, where fc and fu are the fragmentation fractions of a B meson with a c and u quark respectively in proton-proton collisions. Each result is either the first such measurement or an improvement by three orders of magnitude on an existing limit. Separate upper limits are calculated when the muon pair originates from a J/.. mu+ mu- decay. The branching fraction of B+ c. D+ s J/. multiplied by the fragmentation-fraction ratio is measured to be fc fu center dot B -> B+ c. D+ s J/.-> = (1.63 +/- 0.15 +/- 0.13) x 10-5, where the first uncertainty is statistical and the second systematic.
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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). Study of Bc+ → χc π+ decays. J. High Energy Phys., 02(2), 173–30pp.
Abstract: A study of B-c(+) -> chi(c) pi(+) decays is reported using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV, corresponding to an integrated luminosity of 9 fb(-1). The decay B-c(+) -> chi(c2)pi(+) is observed for the first time, with a significance exceeding seven standard deviations. The relative branching fraction with respect to the B-c(+) -> J/psi pi(+) decay is measured to be BBc+ ->chi c2 pi+/BBc+ -> (J/psi pi+) = 0.37 +/- 0.06 +/- 0.02 +/- 0.01, where the first uncertainty is statistical, the second is systematic, and the third is due to the knowledge of the chi(c2) -> J/psi gamma branching fraction. No significant B-c(+) -> chi(+)(c1 pi) signal is observed and an upper limit for the relative branching fraction for the B-c(+) -> chi(c1)pi(+) and B-c(+) -> chi(c2)pi(+) decays of BBc+ ->chi c1 pi+/BBc+ -> chi(c2)pi(+) < 0.49 is set at the 90% confidence level.
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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). A model-independent measurement of the CKM angle γ in partially reconstructed B±→D∗h± decays with D→K0Sh+h-(h=π,K). J. High Energy Phys., 02(2), 118–30pp.
Abstract: A measurement of CP-violating observables in B-+/-->(DK +/-)-K-& lowast; and B-+/--> D-& lowast;pi(+/-) decays is made where the photon or neutral pion from the D-& lowast;-> D gamma or D-& lowast;-> D pi(0) decay is not reconstructed. The D meson is reconstructed in the self-conjugate decay modes, D -> K-S(0)pi(+)pi(-) or D ->(KSK+K-)-K-0. The distribution of signal yields in the D decay phase space is analysed in a model-independent way. The measurement uses a data sample collected in proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of approximately 9 fb(-1). The B-+/-->(DK +/-)-K-& lowast; and B-+/--> D-& lowast;pi(+/-) CP-violating observables are interpreted in terms of hadronic parameters and the CKM angle gamma, resulting in a measurement of gamma=(92(-17)(+21))degrees. The total uncertainty includes the statistical and systematic uncertainties, and the uncertainty due to external strong-phase inputs.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Observation of the B (s) (0) -> J/psi phi phi decay. J. High Energy Phys., 03(3), 040–18pp.
Abstract: The B (s) (0) -> J/psi phi phi decay is observed in pp collision data corresponding to an integrated luminosity of 3 fb(-1) recorded by the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV. This is the first observation of this decay channel, with a statistical significance of 15 standard deviations. The mass of the B (s) (0) meson is measured to be 5367.08 +/- 0.38 +/- 0.15 MeV/c(2). The branching fraction ratio B[B(s)(0) -> J/psi phi phi]/B[B(s)(0) -> J/psi phi] is measured to be 0.0115 +/- 0.0012 (- 0.0009) (+ 0.0005) . In both cases, the first uncertainty is statistical and the second is systematic. No evidence for non-resonant B(s)(0) -> J/psi phi K (+) K (-) or B(s)(0) -> J/psi K (+) K (-) K (+) K (-) decays is found.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Search for decays of neutral beauty mesons into four muons. J. High Energy Phys., 03(3), 001–19pp.
Abstract: A search for the non-resonant decays B-s(0) -> mu(+) mu(-) mu(+)mu(-) and B-0 -> mu(+) mu(-) mu(+) mu(-) is presented. The measurement is performed using the full Run 1 data set collected in proton-proton collisions by the LHCb experiment at the LHC. The data correspond to integrated luminosities of 1 and 2 fb(-1) collected at centre-of-mass energies of 7 and 8 TeV, respectively. No signal is observed and upper limits on the branching fractions of the non-resonant decays at 95% confidence level are determined to be B(B-s(0) -> mu(+) mu(-) mu(+)mu(-)) < 2.5 x 10(-9) B(B-0 -> mu(+) mu(-) mu(+) mu(-)) < 6.9 x 10(-10)
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of CP asymmetry in B-s(0) -> (DsK +/-)-K-/+ decays. J. High Energy Phys., 03(3), 059–28pp.
Abstract: We report the measurements of the CP-violating parameters in B-s(0) -> (DsK +/-)-K--/+ decays observed in pp collisions, using a data set corresponding to an integrated luminosity of 3.0 fb(-1) recorded with the LHCb detector. We measure C-f = 0.73 +/- 0.14 +/- 0.05, A(f)(Delta Gamma) = 0.39 +/- 0.28 +/- 0.15, A(<(f)over) (Delta Gamma)(bar>) = 0.31 +/- 0.28 +/- 0.15, S-f = -0.52 +/- 0.20 +/- 0.07, S-(f) over bar = -0.49 +/- 0.20 +/- 0.07, where the uncertainties are statistical and systematic, respectively. These parameters are used together with the world-average value of the B-s(0) mixing phase, -2 beta(s), to obtain a measurement of the CKM angle gamma from B-s(0) -> (DsK +/-)-K--/+ decays, yielding gamma – (128 (+17)(-22))degrees modulo 180 degrees, where the uncertainty contains both statistical and systematic contributions. This corresponds to 3.8 sigma evidence for CP violation in the interference between decay and decay after mixing.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Search for the lepton-flavour violating decays B-(s)(0) -> e(+/-) mu(-/+). J. High Energy Phys., 03(3), 078–20pp.
Abstract: A search for the lepton-flavour violating decays B-(s)(0) -> e(+/-)mu(-/+) and B-(s)(0) -> e(+/-)mu(-/+) performed based on a sample of proton-proton collision data corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb experiment at centre-of-mass energies of 7 and 8TeV. The observed yields are consistent with the background-only hypothesis. Upper limits on the branching fraction of the B-(s)(0) -> e(+/-)mu(-/+) decays are evaluated both in the hypotheses of an amplitude completely dominated by the heavy eigenstate and by the light eigenstate. The results are B(B-s(0) -> e(+/-)mu(-/+)) < 6.3 (5.4) x 10(-9) and B(B-s(0) -> e(+/-)mu(-/+)) < 7.2(6.0) x 10(-9) at 95% (90%) confidence level, respectively. The upper limit on the branching fraction of the B-0 -> e(+/-)mu(-/+) decay is also evaluated, obtaining B(B-0 -> e(+/-)mu(-/+)) < 1.3 (1.0) x 10(-9) at 95% (90%) confidence level. These are the strongest limits on these decays to date.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). First measurement of the CP-violating phase phi(dd)(s) in B-s(0) -> (K+pi(-))(K-pi(+)) decays. J. High Energy Phys., 03(3), 140–32pp.
Abstract: A flavour-tagged decay-time-dependent amplitude analysis of B-s(0) -> (K+pi(-))(K-pi(+)) decays is presented in the K-+/-pi(-/+) mass range from 750 to 1600 MeV/c(2). The analysis uses pp collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0 fb(-1). Several quasi-two-body decay modes are considered, corresponding to K-+/-pi(-/+) combinations with spin 0, 1 and 2, which are dominated by the K-0(*)(800)(0) and K-0(*)(1430)(0), the K*(892)(0) and the K-2(*)(1430)(0) resonances, respectively. The longitudinal polarisation fraction for the B-s(0) -> K-*(892)(0) (K*) over bar (892)(0) decay is measured as f(L) = 0.208 +/- 0.032 +/- 0.046, where the first uncertainty is statistical and the second is systematic. The first measurement of the mixing-induced CP-violating phase in phi(d (d) over bar)(s), in b -> d (s) over bars transitions is performed, yielding a value of phi(d (d) over bar)(s)= -0.10 +/- 0.13 (stat) +/- 0.14 (syst) rad.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2019). Measurement of the ratio of branching fractions of the decays0(2S) and arrange Lambda. J. High Energy Phys., 03(3), 126–16pp.
Abstract: Using pp collisions corresponding to 3 fb integrated luminosity, recorded by the LHCb experiment at centre- of- mass energies of 7 and 8 TeV, the ratio of branching fractions B (0b ! (2 S) ) =B (0b ! J= ) = 0 : 513 0 : 023 (stat) 0 : 016 (syst) 0 : 011 (B) is determined. The first uncertainty is statistical, the second is systematic and the third is due to the external branching fractions used.
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