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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Angular analysis of the B-0 -> K*(0) e(+) e(-) decay in the low-q(2) region. J. High Energy Phys., 04(4), 064–23pp.
Abstract: An angular analysis of the B-0 -> K(*0)e(+) e(-) decay is performed using a data sample, corresponding to an integrated luminosity of 3.0 fb(-1), collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV during 2011 and 2012. For the first time several observables are measured in the dielectron mass squared (q(2)) interval between 0.002 and 1.120 GeV2/c(4). The angular observables F-L and A(T)(Re) which are related to the K-*0 polarisation and to the lepton forward-backward asymmetry, are measured to be F-L = 0.16 +/- 0.06 +/- 0.03 and A(T)(Re) = 0.10 +/- 0.18 +/- 0.05, where the first uncertainty is statistical and the second systematic. The angular observables A(T)((2)) and A(T)(Im) which are sensitive to the photon polarisation in this q(2) range, are found to be A(T)((2)) = – 0.23 +/- 0.23 +/- 0.05 and A(T)(Im) = 0.14 +/- 0.22 +/- 0.05. The results are consistent 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). Angular analysis and differential branching fraction of the decay B-s(0) -> phi mu(+)mu(-). J. High Energy Phys., 09(9), 179–35pp.
Abstract: An angular analysis and a measurement of the differential branching fraction of the decay B-s(0) -> phi mu(+)mu(-) are presented, using data corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions recorded by the LHCb experiment at root s = 7 and 8 TeV. Measurements are reported as a function of q(2), the square of the dimuon invariant mass and results of the angular analysis are found to be consistent with the Standard Model. In the range 1 < q(2) < 6 GeV2/c(4), where precise theoretical calculations are available, the differential branching fraction is found to be more than 3 sigma below the Standard Model predictions.
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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). Angular moments of the decay Lambda(0)(b) -> Lambda mu(+)mu(-) at low hadronic recoil. J. High Energy Phys., 09(9), 146–27pp.
Abstract: An analysis of the angular distribution of the decay Lambda(0)(b) -> Lambda mu(+)mu(-) is presented, using data collected with the LHCb detector between 2011 and 2016 and corresponding to an integrated luminosity of approximately 5 fb(-1). Angular observables are determined using a moment analysis of the angular distribution at low hadronic recoil, corresponding to the dimuon invariant mass squared range 15 < q(2) < 20 GeV2/c(4). The full basis of observables is measured for the first time. The lepton-side, hadron-side and combined forward-backward asymmetries of the decay are determined to be A(FB)(l) = -0.39 +/- 0.04 (stat) +/- 0.01 (syst), AFB(h) = -0.30 +/- 0.05 (stat) +/- 0.02 (syst), A(FB)(lh) = +0.25 +/- 0.04 (stat) +/- 0.01 (syst). The measurements are consistent with Standard Model predictions.
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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. (2017). Test of lepton universality with B-0 -> K*(0)l(+)l(-) decays. J. High Energy Phys., 08(8), 055–31pp.
Abstract: A test of lepton universality, performed by measuring the ratio of the branching fractions of the B-0 -> K*(0)mu(+) mu(-) and B-0 -> K*e(+)e(-) decays, R-K*0, is presented. The K*(0) meson is reconstructed in the final state K+pi(-), which is required to have an invariant mass within 100 MeV/c(2) of the known K*(892)(0) mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb(-1), collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q(2), to be R-K*0 – {0.66(-0.007)(+0.11)(stat) +/- 0.03(syst) for 0.045 < q(2) < GeV2/c(4), 0.69(-0.07)(+0.11)(stat) +/- 0.05(syst) for 1.1 < q(2) < 6.0 GeV2/c(4). The corresponding 95.4% confidence level intervals are [0.52, 0.89] and [0.53, 0.94]. The results, which represent the most precise measurements of R-K*0 to date, are compatible with the Standard Model expectations at the level of 2.1-2.3 and 2.4-2.5 standard deviations in the two q(2) regions, respectively.
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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). Search for the lepton flavour violating decay B+ -> K+mu(-)tau(+) using Bs20 decays. J. High Energy Phys., 06(6), 129–19pp.
Abstract: A search is presented for the lepton flavour violating decay B+ -> K+mu (-)tau (+) using a sample of proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb(-1). The tau leptons are selected inclusively, primarily via decays with a single charged particle. The four-momentum of the tau lepton is determined by using B+ mesons from Bs20 -> B+K- decays. No significant excess is observed, and an upper limit is set on the branching fractionB(B+-> K+mu (-)tau (+))<3.9x10(-5)at90%confidence level.The obtained limit is comparable to the world-best limit.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Observations of Lambda(0)(b) -> Lambda K+pi(-) and Lambda(0)(b) -> Lambda K+K- decays and searches for other Lambda(0)(b) and Xi(0)(b) decays to Lambda h(+)h '(-) final states. J. High Energy Phys., 05(5), 081–22pp.
Abstract: A search is performed for the charmless three-body decays of the Lambda(0)(b) and Xi(0)(b) baryons to the final states Lambda h(+)h'(-), where h(') = pi or K. The analysis is based on a data sample, corresponding to an integrated luminosity of 3 fb-1 of pp collisions, collected by the LHCb experiment. The Lambda(0)(b) -> Lambda K+pi(-) and Lambda(0)(b) -> Lambda K+K- decays are observed for the first time and their branching fractions and CP asymmetry parameters are measured. Evidence is seen for the Lambda(0)(b) -> Lambda pi(+)pi(-) decay and limits are set on the branching fractions of Xi(0)(b) baryon decays to the Lambda h(+)h(-) final states.
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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. (2021). Searches for 25 rare and forbidden decays of D+ and Ds+ mesons. J. High Energy Phys., 06(6), 044–24pp.
Abstract: A search is performed for rare and forbidden charm decays of the form D+-> hl+l -/+, where h(+/-) is a pion or kaon and l((')+/-) is an electron or muon. The measurements are performed using proton-proton collision data, corresponding to an integrated luminosity of 1.6 fb(-1), collected by the LHCb experiment in 2016. No evidence is observed for the 25 decay modes that are investigated and 90 % confidence level limits on the branching fractions are set between 1.4 x 10(-8) and 6.4 x 10(-6). In most cases, these results represent an improvement on existing limits by one to two orders of magnitude.
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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). Search for the rare decays W+ → Ds+γ and Z → D0 γ at LHCb. Chin. Phys. C, 47(9), 093002–13pp.
Abstract: A search for the rare decays W+ -> D-s(+)gamma and Z -> D-0 gamma and is performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 2.0fb(-1). No significant signal is observed for either decay mode and upper limits on their branching fractions are set using W+ -> mu(+)nu and Z ->mu(+)mu(-)decays as normalization channels. The upper limits are and at 95% confidence level for W+ -> D-s(+)gamma and Z -> D-0 gamma the and decay modes, respectively. This is the first reported search for Z -> D-0 gamma the decay, while the upper limit on the Z -> D-0 gamma branching fraction improves upon the previous best limit.
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LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Search for the rare decay B-0 -> J/psi phi. Chin. Phys. C, 45(4), 043001–14pp.
Abstract: A search for the rare decay B-0 -> J/psi phi, is performed using pp collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). No significant signal of the decay is observed and an upper limit of 1.1 x 10(-7) at 90% confidence level is set on the branching fraction.
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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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