LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2017). Search for Baryon-Number Violating Xi(0)(b) Oscillations. Phys. Rev. Lett., 119(18), 181807–9pp.
Abstract: A search for baryon-number violating Xi(0)(b) oscillations is performed with a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 3 fb(-1). The baryon number at the moment of production is identified by requiring that the Xi(0)(b) come from the decay of a resonance Xi(b)*(-) -> Xi(0)(b)pi(-) or Xi(b)'(-) -> Xi(0)(b)pi(-) and the baryon number at the moment of decay is identified from the final state using the decays Xi(0)(b) -> Xi(0)(c)pi(-) , Xi(+-)(c) -> pK(-)pi(+). No evidence of baryon-number violation is found, and an upper limit at the 95% confidence level is set on the oscillation rate of omega < 0.08 ps(-1), where. is the associated angular frequency.
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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). Observation of the Decay Xi(-)(b) -> pK(-)K(-). Phys. Rev. Lett., 118(7), 071801–11pp.
Abstract: Decays of the Xi(-)(b) and Omega(-)(b) baryons to the charmless final states ph(-)h'(-), where h((')) denotes a kaon or pion, are searched for with the LHCb detector. The analysis is based on a sample of proton-proton collision data collected at center-of-mass energies root s = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). The decay Xi(-)(b) -> pK(-)K(-) is observed with a significance of 8.7 standard deviations, and evidence at the level of 3.4 standard deviations is found for the Xi(-)(b) -> pK(-)pi(-) decay. Results are reported, relative to the B- -> K+K-K- normalization channel, for the products of branching fractions and b-hadron production fractions. The branching fractions of Xi(-)(b) -> pK(-)pi(-) and Xi(-)(b) -> p pi(-)pi(-) relative to Xi(-)(b) -> pK(-)K(-) decays are also measured.
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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. (2019). Search for Lepton-Universality Violation in B+ -> K(+)l(+)l(-) Decays. Phys. Rev. Lett., 122(19), 191801–13pp.
Abstract: A measurement of the ratio of branching fractions of the decays B+ -> K+mu(+)mu(-) and B+ -> K(+)e(+)e(-) is presented. The proton-proton collision data used correspond to an integrated luminosity of 5.0 fb(-1) recorded with the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. For the dilepton mass-squared range 1.1 < q(2) < 6.0 GeV2/c(4) the ratio of branching fractions is measured to be R-K = 0.846(-0.054-0.014)(+0.060+0.016), where the first uncertainty is statistical and the second systematic. This is the most precise measurement of R-K to date and is compatible with the standard model at the level of 2.5 standard deviations.
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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. (2019). Observation of B-(s)(0) -> J/psi p(p)over-bar Decays and Precision Measurements of the B-(s)(0) Masses. Phys. Rev. Lett., 122(19), 191804–10pp.
Abstract: The first observation of the decays B-(s)(0) -> J/psi p (p) over bar is reported, using proton-proton collision data corresponding to an integrated luminosity of 5.2 fb(-1), collected with the LHCb detector. These decays are suppressed due to limited available phase space, as well as due to Okubo-Zweig-Iizuka or Cabibbo suppression. The measured branching fractions are beta(B-(s)(0) -> J/psi p (p) over bar). [4.51 +/- 0.40(stat)+/- 0.44(syst)] x 10(-7), BB(s)0 -> J/psi p (p) over bar) = 3.58 +/- 0.19(stat) 0.39(syst)] x 10(-6). For the B-s(0) meson, the result is much higher than the expected value of O(10(-9)). The small available phase space in these decays also allows for the most precise single measurement of both the B-0 mass as 5279.74 +/- 0.30(stat) 0.10(syst) MeV and the B-s(0) mass as 5366.85 +/- 0.19(stat) +/- 0.13(syst) MeV.
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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. (2019). Search for CP Violation in D-s(+) -> K-S(0)pi(+), D+ -> (KSK+)-K-0, and D+ -> phi pi(+) Decays. Phys. Rev. Lett., 122(19), 191803–11pp.
Abstract: A search for charge-parity (CP) violation in Cabibbo-suppressed D-s(+) -> K-S(0)pi(+), D+ -> (KSK+)-K-0, and D+ -> phi pi(+) decays is reported using proton-proton collision data, corresponding to an integrated luminosity of 3.8 fb(-1), collected at a center-of-mass energy of 13 TeV with the LHCb detector. High-yield samples of kinematically and topologically similar Cabibbo-favored D-(s())+ decays are analyzed to subtract nuisance asymmetries due to production and detection effects, including those induced by CP violation in the neutral kaon system. The results are A(CP)(D-s(+) -> K-S(0)pi(+)) = (1.3 +/- 1.9 +/- 0.5) x 10(-3), A(CP)(D+ -> (KSK+)-K-0) = (-0.09 +/- 0.65 +/- 0.48) x 10(-3), A(CP)(D+ -> phi pi(+)) = (0.05 +/- 0.42 +/- 0.29) x 10(-3), where the first uncertainties are statistical and the second systematic. They are the most precise measurements of these quantities to date, and are consistent with CP symmetry. A combination with previous LHCb measurements, based on data collected at 7 and 8 TeV, is also reported.
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