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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 CP violation using triple product asymmetries in Lambda(0)(b) -> pK(-) pi(+) pi(-), Lambda(0)(b) -> pK(-) K+ K- and Xi(0)(b) -> pK(-) K- pi(+) decays. J. High Energy Phys., 08(8), 039–27pp.
Abstract: A search for CP and P violation using triple- product asymmetries is performed with Lambda(0)(b) -> pK(-) pi(+) pi(-), Lambda(0)(b) -> pK(-) K+ K- and Xi(0)(b) -> pK(-) K- pi(+) decays. The data sample corresponds to integrated luminosities of 1.0 fb(-1) and 2.0 fb(-1), recorded with the LHCb detector at centre- of- mass energies of 7TeV and 8TeV, respectively. The CP- and P-violating asymmetries are measured both integrating over all phase space and in speci fi c phase- space regions. No signi fi cant deviation from CP or P symmetry is found. The fi rst observation of Lambda(0)(b) -> pK(-) chi(c0) (1P)(->pi(+) pi(-), K+ K-) decay is also reported.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurement of the mass and lifetime of the Omega(-)(b) baryon. Phys. Rev. D, 93(9), 092007–12pp.
Abstract: A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb(-1) collected by LHCb at root s = 7 and 8 TeV, is used to reconstruct 63 +/- 9 Omega(-)(b) -> Omega(0)(c)pi(-), Omega(0)(c) -> pK(-)K(-)pi(+) decays. Using the Xi(-)(b) ->Xi(0)(c)pi(-), Xi(0)(c) -> pK(-)K(-)pi(+) decay mode for calibration, the lifetime ratio and the absolute lifetime of the Omega(-)(b) baryon are measured to be tau(Omega b-)/tau(Xi b-) = 1.11 +/- 0.16 +/- 0.03, tau(Omega b-) = 1.78 +/- 0.26 +/- 0.05 +/- 0.06 ps, where the uncertainties are statistical, systematic and from the calibration mode (for tau(Omega b-) only). A measurement is also made of the mass difference, m(Omega b-) – m(Xi b-), and the corresponding Omega(-)(b) mass, which yields m(Omega b-) – m(Xi b-) = 247.4 +/- 3.2 +/- 0.5 MeV/c(2), m(Omega b-) = 6045.1 +/- 3.2 +/- 0.5 +/- 0.6 MeV/c(2). These results are consistent with previous measurements.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurement of the Difference of Time-Integrated CP Asymmetries in D-0 -> K-K+ and D-0 -> pi(-)pi(+) Decays. Phys. Rev. Lett., 116(19), 191601–10pp.
Abstract: A search for CP violation in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays is performed using pp collision data, corresponding to an integrated luminosity of 3 fb(-1), collected using the LHCb detector at center-of-mass energies of 7 and 8 TeV. The flavor of the charm meson is inferred from the charge of the pion in D*(+) -> D-0 pi(+) and D*(-) -> (D) over bar (0)pi(-) decays. The difference between the CP asymmetries in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays, Delta A(CP) A(CP)(K-K+) – A(CP)(pi(-)pi(+)), is measured to be [-0.10 +/- 0.08(stat) +/- 0.03(syst)]%. This is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Study of psi(2S) production and cold nuclear matter effects in pPb collisions at root s(NN)=5 TeV. J. High Energy Phys., 03(3), 133–21pp.
Abstract: The production of psi(2S) mesons is studied in dimuon final states using proton-lead (pPb) collision data collected by the LHCb detector. The data sample corresponds to an integrated luminosity of 1.6 nb(-1). The nucleon-nucleon centre-of-mass energy of the pPb collisions is root s(NN) = 5 TeV. The measurement is performed using psi(2S) mesons with transverse momentum less than 14 GeV/c and rapidity y in the ranges 1.5 < y < 4.0 and -5.0 < y < -2.5 in the nucleon-nucleon centre-of-mass system. The forward-backward production ratio and the nuclear modi fi cation factor are determined for psi(2S) mesons. Using the production cross-section results of psi(2S) and J/psi mesons from b-hadron decays, the b (b) over bar cross-section in pPb collisions at root s(NN) = 5 TeV is obtained.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). First observation of the rare B+ -> D+K+pi(-) decay. Phys. Rev. D, 93(5), 051101–11pp.
Abstract: The B+ -> D+K+pi(-) decay is observed in a data sample corresponding to 3.0 fb(-1) of pp collision data recorded by the LHCb experiment during 2011 and 2012. The signal significance is 8 sigma and the branching fraction is measured to be B(B+ -> D+K+pi(-)) = (5.31 +/- 0.90 +/- 0.48 +/- 0.35) x 10(-6), where the uncertainties are statistical, systematic and due to the normalization mode B+ -> D-K+pi(+), respectively. The Dalitz plot appears to be dominated by broad structures. Angular distributions are exploited to search for quasi-two-body contributions from B+ -> D*(2)(2460)K-0(+) and B+ -> (D+K*)(892)(0) decays. No significant signals are observed and upper limits are set on their branching fractions.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Search for the lepton-flavour violating decay D-0 -> e(+/-)mu(-/+). Phys. Lett. B, 754, 167–175.
Abstract: A search for the lepton-flavour violating decay D-0 -> e(+/-)mu(-/+) is made with a dataset corresponding to an integrated luminosity of 3.0 fb(-1) of proton-proton collisions at centre-of-mass energies of 7 TeV and 8 TeV, collected by the LHCb experiment. Candidate D-0 mesons are selected using the decay D*(+) -> D-0 pi(+) and the D-0 -> e(+/-)mu(+) branching fraction is measured using the decay mode D-0 -> K-pi(+) as a normalization channel. No significant excess of D-0 -> e(+/-)mu(-/+) candidates over the expected background is seen, and a limit is set on the branching fraction, B(D-0 -> e(+/-)mu(-/+)) < 1.3 x10(-8), at 90% confidence level. This is an order of magnitude lower than the previous limit and it further constrains the parameter space in some leptoquark models and in supersymmetric models with R-parity violation.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurements of prompt charm production cross-sections in pp collisions at root s=13 TeV. J. High Energy Phys., 03(3), 159–43pp.
Abstract: Production cross-sections of prompt charm mesons are measured with the first data from pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 4.98 +/- 0.19 pb(-1) collected by the LHCb experiment. The production cross-sections of D-0, D+, D (s) (+) , and D*+ mesons are measured in bins of charm meson transverse momentum, p(T), and rapidity, y, and cover the range 0 < p(T) < 15GeV/c and 2.0 < y < 4.5. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of 1 < p(T) < 8 GeV/c are found to be sigma(pp -> D-0 X) = 2460 +/- 3 +/- 130 μb sigma(pp -> D+ X) = 1000 +/- 3 +/- 110 μb sigma(pp -> Ds+X) = 460 +/- 13 +/- 100 μb sigma(pp -> D*+ X) = 880 +/- 5 +/- 140 μb where the uncertainties are due to statistical and systematic uncertainties, respectively.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Model-independent measurement of mixing parameters in D-0 -> K-S(0)pi(+)pi(-) decays. J. High Energy Phys., 04(4), 033–26pp.
Abstract: The first model-independent measurement of the charm mixing parameters in the decay D-0 -> K-S(0)pi(+)pi(-) is reported, using a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb(-1) at a centre-of-mass energy of 7 TeV. The measured values are x = (0.86 +/- 0.53 +/- 0.17) x 10(-2), y = (+0.03 +/- 0.46 +/- 0.13) x 10(-2), where the first uncertainties are statistical and include small contributions due to the external input for the strong phase measured by the CLEO collaboration, and the second uncertainties are systematic.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Studies of the resonance structure in D-0 -> (KSK +/-)-K-0 pi(-/+) decays. Phys. Rev. D, 93(5), 052018–35pp.
Abstract: Amplitude models are applied to studies of resonance structure in D-0 -> (KSK-)-K-0 pi(+) and D-0 -> (KSK+)-K-0 pi(-) decays using pp collision data corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb experiment. Relative magnitude and phase information is determined, and coherence factors and related observables are computed for both the whole phase space and a restricted region of 100 MeV/c(2) around the K*(892)(+/-) resonance. Two formulations for the K pi S-wave are used, both of which give a good description of the data. The ratio of branching fractions B(D-0 -> (KSK+)-K-0 pi(-))/B(D-0 -> (KSK-)-K-0 pi(+)) is measured to be 0.655 +/- 0.004(stat) +/- 0.006(syst) over the full phase space and 0.370 +/- 0.003(stat) +/- 0.012(syst) in the restricted region. A search for CP violation is performed using the amplitude models and no significant effect is found. Predictions from SU(3) flavor symmetry for K*(892)K amplitudes of different charges are compared with the amplitude model results.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Amplitude analysis of B-0 -> (D)over-bar0K(+)pi(-) decays. Phys. Rev. D, 92(1), 012012–24pp.
Abstract: The Dalitz plot distribution of B-0 -> (D) over bar K-0(+)pi(-) decays is studied using a data sample corresponding to 3.0 fb(-1) of pp collision data recorded by the LHCb experiment during 2011 and 2012. The data are described by an amplitude model that contains contributions from intermediate K* (892)(0), K*(1410)(0), K-2*(1430)(0) and D-2(*)(2460)(-) resonances. The model also contains components to describe broad structures, including the K-0(*)(1430)(0) and D-0(*)(2400)(-) resonances, in the K pi S-wave and the D pi S-and P-waves. The masses and widths of the D-0*(2400)(-) and D-2(*)(2460)(-) resonances are measured, as are the complex amplitudes and fit fractions for all components included in the amplitude model. The model obtained will be an integral part of a future determination of the angle gamma of the Cabibbo-Kobayashi-Maskawa quark mixing matrix using B-0 -> DK+pi(-) decays.
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