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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 a dimuon resonance in the Upsilon mass region. J. High Energy Phys., 09(9), 147–21pp.
Abstract: A search is performed for a spin-0 boson, phi, produced in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, using prompt phi -> mu(+)mu(-) decays and a data sample corresponding to an integrated luminosity of approximately 3.0 fb(-1) collected with the LHCb detector. No evidence is found for a signal in the mass range from 5.5 to 15 GeV. Upper limits are placed on the product of the production cross-section and the branching fraction into the dimuon final state. The limits are comparable to the best existing over most of the mass region considered and are the first to be set near the Upsilon resonances.
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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 beautiful tetraquarks in the Î¥(1S)(+-) invariant-mass spectrum. J. High Energy Phys., 10(10), 086–22pp.
Abstract: The Υ(1 S) invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two b quarks, X bbbb. The analysis is based on a data sample of pp collisions recorded with the LHCb detector at centre-of-mass energies s = 7, 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb. No signi fi cant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the X bbbb state. The limits are set in the fi ducial volume where all muons have pseudorapidity in the range [2 : 0; 5 : 0], and the X bbbb state has rapidity in the range [2 : 0; 4 : 5] and transverse momentum less than 15 GeV/c.
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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). Central exclusive production of J/psi and (2S) mesons in pp collisions at root s=13 TeV. J. High Energy Phys., 10(10), 167–27pp.
Abstract: Measurements are reported of the central exclusive production of J= and ( 2 S) mesons in pp collisions at a centre- of- mass energy of 13 TeV. Backgrounds are signi fi cantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross- sections and the branching fractions for the decays to dimuons, where both muons are within the pseudorapidity range 2 : 0 < < 4 : 5, are measured to be The fi rst uncertainties are statistical, the second are systematic, and the third are due to the luminosity determination. The cross- sections are also measured di ff erentially for meson rapidities between 2.0 and 4.5. Good agreement is observed with theoretical predictions. Photoproduction cross- sections are derived and compared to previous experiments, and a deviation from a pure power- law extrapolation of lower energy data is observed.
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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 the time-integrated CP asymmetry in D (0) -> K (S) (0) K (S) (0) decays. J. High Energy Phys., 11(11), 048–19pp.
Abstract: A measurement of the time-integrated CP asymmetry in D (0) -> K (S) (0) K (S) (0) decays is reported. The data correspond to an integrated luminosity of about 2 fb(-1) collected in 2015-2016 by the LHCb collaboration in pp collisions at a centre-of-mass energy of 13 TeV. The D (0) candidate is required to originate from a D (*+) -> D (0) pi (+) decay, allowing the determination of the flavour of the D (0) meson using the pion charge. The D (0) -> K (+) K (-) decay, which has a well measured CP asymmetry, is used as a calibration channel. The CP asymmetryfor D (0) -> K (S) (0) K (S) (0) is measured to be where the first uncertainty is statistical and the second is systematic. This result is combined with the previous LHCb measurement at lower centre-of-mass energies to obtain A(CP) (D-0 -> K-S(0) K-S(0)) = (2.3 +/- 2.8 +/- 0.9)%.
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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). Resonances and CP violation in B-s(0) and (B)over-bar(s)(0) -> j psi K+K- decays in the mass region above the I center dot(1020). J. High Energy Phys., 08(8), 037–28pp.
Abstract: The decays of B (s) (0) and mesons into the J/psi K (+) K (-) final state are studied in the K (+) K (-) mass region above the I center dot(1020) meson in order to determine the resonant substructure and measure the CP-violating phase, I center dot (s) , the decay width, I“ (s) , and the width difference between light and heavy mass eigenstates, Delta I” (s) . A decay-time dependent amplitude analysis is employed. The data sample corresponds to an integrated luminosity of 3 fb(-1) produced in 7 and 8 TeV pp collisions at the LHC, collected by the LHCb experiment. The measurement determines I center dot (s) = 119 +/- 107 +/- 34 mrad. A combination with previous LHCb measurements using similar decays into the J/psi pi (+) pi (-) and J/psi I center dot(1020) final states gives I center dot (s) = 1 +/- 37 mrad, consistent with the Standard Model prediction.
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