BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2014). Measurements of direct CP asymmetries in B -> X-s gamma decays using sum of exclusive decays. Phys. Rev. D, 90(9), 092001–12pp.
Abstract: We measure the direct CP violation asymmetry, A(CP), in B -> X-s gamma and the isospin difference of the asymmetry, Delta A(CP), using 429 fb(-1) of data collected at Upsilon(4S) resonance with the BABAR detector at the PEP- II asymmetric- energy e(+)e(-) storage rings operating at the SLAC National Accelerator Laboratory. B mesons are reconstructed from ten charged B final states and six neutral B final states. We find A(CP) = +(1.7 +/- 1.9 +/- 1.0)%, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between A(CP) for charged and neutral decay modes, Delta A(CP) = +(5.0 +/- 3.9 +/- 1.5)%. Using the value of Delta A(CP), we also provide 68% and 90% confidence intervals on the imaginary part of the ratio of theWilson coefficients corresponding to the chromomagnetic dipole and the electromagnetic dipole transitions.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurements of long-range near-side angular correlations in root sNN=5TeV proton-lead collisions in the forward region. Phys. Lett. B, 762, 473–483.
Abstract: Two-particle angular correlations are studied in proton-lead collisions at a nucleon-nucleon centre-ofmass energy of root sNN= 5 TeV, collected with the LHCb detector at the LHC. The analysis is based on data recorded in two beam configurations, in which either the direction of the proton or that of the lead ion is analysed. The correlations are measured in the laboratory system as a function of relative pseudorapidity, Delta eta, and relative azimuthal angle, Delta phi, for events in different classes of event activity and for different bins of particle transverse momentum. In high-activity events a long-range correlation on the near side, Delta phi approximate to 0, is observed in the pseudorapidity range 2.0 < eta < 4.9. This measurement of long-range correlations on the near side in proton-lead collisions extends previous observations into the forward region up to eta= 4.9. The correlation increases with growing event activity and is found to be more pronounced in the direction of the lead beam. However, the correlation in the direction of the lead and proton beams are found to be compatible when comparing events with similar absolute activity in the direction analysed.
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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), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Measurements of prompt charm production cross-sections in pp collisions at root s=5TeV. J. High Energy Phys., 06(6), 147–41pp.
Abstract: Production cross-sections of prompt charm mesons are measured using data from pp collisions at the LHC at a centre-of-mass energy of 5TeV. The data sample corresponds to an integrated luminosity of 8 : 60 +/- 0 : 33 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. They cover the rapidity range 2 : 0 < y < 4 : 5 and transverse momentum ranges 0 < p(T) < 10 GeV/c for D-0 and D+ and 1 < p(T) < 10 GeV/c for D-s(+) and D*(+) mesons. The inclusive cross- sections for the four mesons, including charge-conjugate states, within the range of 1 < p(T) < 8 GeV/c are determined to be sigma (pp -> D-0 X) – 1004 +/- 3 +/- 54 μb; sigma ( pp -> D+ X) = 402 +/- 2 +/- 30 μb; sigma ( pp -> Ds+X) = 170 +/- 4 +/- 16 μb; sigma ( pp -> D*(+) X) = 421 +/- 5 +/- 36 μb; where the uncertainties are statistical and systematic, respectively.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2020). Measurements of the Absolute Branching Fractions of B-+/- -> K(+/-)Xc(c)over-bar. Phys. Rev. Lett., 124(15), 152001–8pp.
Abstract: A study of the two-body decays B-+/- -> Xc (c) over barK +/-, where X-c (c) over bar refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb(-1). The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B-+/- -> X(3872)K+ at the 3 sigma level. The absolute branching fraction B[B+ -> X(3872)K+] = [2.1 +/- 0.6(stat) +/- 0.3(syst)] x 10(-4) is measured for the first time. It follows that B[X(3872) -> J/psi pi(+)pi(-)] = (4.1 +/- 1.3)%, supporting the hypothesis of a molecular component for this resonance.
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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). Measurements of the branching fractions of Lambda(+)(c) -> p pi(-)pi(+), Lambda(+)(c) -> pK(-)K(+), and Lambda(+)(c) -> p pi K-(+). J. High Energy Phys., 03(3), 043–23pp.
Abstract: The ratios of the branching fractions of the decays do Lambda(+)(c) -> , p pi(-)pi(+), Lambda(+->)(c) pK(-)K(+), and Lambda(+)(c) -> p pi K--(+) with respect to the Cabibbo-favoured Lambda(+)(c) -> pK(-)pi(+) decay are measured using proton-proton collision data collected with the LHCb experiment at a 7 TeV centre-of-mass energy and corresponding to an integrated luminosity of 1.0 fb(-1): B(Lambda(+)(c) -> p pi(-)pi(+))/B(Lambda(+)(c) -> pK(-)pi(+)) = (7.44 +/- 0.08 +/- 0.18)%. B(Lambda(+)(c) -> pK(-)K(+))/B(Lambda(+)(c) -> pK(-)pi(+) = (1.70 +/- 0.03 +/- 0.03)%, B(Lambda(+)(c) -> p pi(-)pi K-+(+))/B(Lambda(+)(c) -> pK(-)pi(+) = (0.165 +/- 0.015 +/- 0.005)%, where the uncertainties are statistical and systematic, respectively. These results are the most precise measurements of these quantities to date. When multiplied by the world average value for B(Lambda(+)(c) -> p pi(-)pi(+)), the corresponding branching fractions are B(Lambda(+)(c) -> p pi(-)pi(+) = (4.72 +/- 0.05 +/- 0.11 +/- 0.25) x 10(-3), B(Lambda(+)(c) -> pK(-)K(+)) = (1.08 +/- 0.02 +/- 0.02 +/- 0.06) x 10(-3), B(Lambda(+)(c) -> , p pi K--(+)) = (1.04 +/- 0.09 +/- 0.03 +/- 0.05) x 10(-4), where the final uncertainty is due to B(Lambda(+)(c) -> pK(-)pi(+)).
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurements of the S-wave fraction in B-0 -> K+ pi(-) mu(+) mu(-) decays and the B-0 -> K*(892)(0) mu(+) mu(-) differential branching fraction. J. High Energy Phys., 11(11), 047–30pp.
Abstract: A measurement of the differential branching fraction of the decay B-0 -> K* (892)(0) mu(+)mu(-) is presented together with a determination of the S-wave fraction of the K+ pi(-) system in the decay B-0 -> K+ pi-mu(+)mu(-). The analysis is based on pp-collision data corresponding to an integrated luminosity of 3 fb(-1) collected with the LHCb experiment. The measurements are made in bins of the invariant mass squared of the dimuon system, q(2). Precise theoretical predictions for the differential branching fraction of B-0 -> K* (892)(0) mu(+) mu(-) decays are available for the q(2) region 1.1 < q(2) < 6.0 GeV2/c(4). In this q(2) region, for the K+pi(-) invariant mass range 796 < m(K pi) < 996MeV/c(2), the S-wave fraction of the K+pi(-) system in B-0 -> K+pi(-)mu(+)mu(-) decays is found to be F-S – 0.101 +/- 0.017(stat) +/- 0: 009(syst), and the differential branching fraction of B-0 -> K* (892)(0) mu(+)mu(-) decays is determined to be dB/dq(2) = (0.392(-0.019)(+ 0.020)(stat) +/- 0.010(syst) +/- 0.027(norm)) x 10(-7) c(4)/GeV2. The differential branching fraction measurements presented are the most precise to date and are found to be in agreement with Standard Model predictions.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Model-independent confirmation of the Z(4430)(-) state. Phys. Rev. D, 92(11), 112009–15pp.
Abstract: The decay B-0 -> psi(2S)K+pi(-) is analyzed using 3 fb(-1) of pp collision data collected with the LHCb detector. A model-independent description of the psi(2S)pi mass spectrum is obtained, using as input the K pi mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the psi(2S)pi mass spectrum can be described in terms of K pi reflections alone is rejected with more than 8 sigma significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the Z(4430)(-) exotic state.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Model-Independent Evidence for J/psi p Contributions to Lambda(0)(b) -> J/psi pK(-) Decays. Phys. Rev. Lett., 117(8), 082002–9pp.
Abstract: The data sample of Lambda(0)(b) -> J/psi pK(-) decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb(-1), is inspected for the presence of J/psi p or J/psi K- contributions with minimal assumptions about K(-)p contributions. It is demonstrated at more than nine standard deviations that Lambda(0)(b) -> J/psi pK(-) decays cannot be described with K- p contributions alone, and that J/psi K- contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P-c(+)-> J/psi p charmonium-pentaquark states in the same data sample.
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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). Model-independent measurement of charm mixing parameters in Bbar → D0(→ K0Sπ+π-)μ-νbar_μX decays. Phys. Rev. D, 108(5), 052005–17pp.
Abstract: A measurement of charm mixing and CP-violating parameters is reported, using B over bar -> D0(-> K0S pi+pi-)x mu- nu over bar μX decays reconstructed in proton-proton collisions collected by the LHCb experiment during the years 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb-1. The measured mixing and CP-violating parameters are xCP = [4.29 1 1.48(stat) 1 0.26(syst)] x 10-3, yCP = [12.61 1 3.12(stat) 1 0.83(syst)] x 10-3, Ax = [-0.77 1 0.93(stat) 1 0.28(syst)] x 10-3, Ay = [3.01 1 1.92(stat) 1 0.26(syst)] x 10-3. The results are complementary to and consistent with previous measurements. A combination with the recent LHCb analysis of D*+ -> D0(-> K0S pi+ pi-)pi+ decays is reported.
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