LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2017). Measurement of the shape of the Lambda(0)(b) ->+ Lambda(+)(c) mu(-)(nu)over-bar μdifferential decay rate. Phys. Rev. D, 96(11), 112005–15pp.
Abstract: A measurement of the shape of the differential decay rate and the associated Isgur-Wise function for the decay Lambda(0)(b) ->+ Lambda(+)(c) mu(-) is reported, using data corresponding to 3 fb(-1) collected with the LHCb detector in proton-proton collisions. The Lambda(+)(c) mu(-)(nu) over bar μ(+anything) final states are reconstructed through the detection of a muon and Lambda(+)(c) baryon decaying into pK(-)pi(+), and the decay Lambda(0)(b) -> Lambda(+)(c)pi(+)pi(-)mu(-)(nu) over bar μare used to determine contributions from Lambda(0)(b) -> Lambda(c)*(+)mu(-)(nu) over bar μdecays. The measured dependence of the differential decay rate upon the squared four-momentum transfer between the heavy baryons, q(2), is compared with expectations from heavy-quark effective theory and from unquenched lattice QCD 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). Study of prompt D-0 meson production in pPb collisions at root(NN)-N-s=5 TeV. J. High Energy Phys., 10(10), 090–28pp.
Abstract: Production of prompt D-0 mesons is studied in proton-lead and lead-proton collisions recorded at the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of 1.58 +/- 0.02 nb(-1) recorded at a nucleon-nucleon centre-of-mass energy of root(NN)-N-s = 5 TeV. Measurements of the differential cross-section, the forward-backward production ratio and the nuclear modification factor are reported using D-0 candidates with transverse momenta less than 10 GeV/c and rapidities in the ranges 1.5 < y* < 4.0 and -5.0 < y* < -2.5 in the nucleon-nucleon centre-of-mass system.
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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). Observation of the Doubly Charmed Baryon Xi(++)(cc). Phys. Rev. Lett., 119(11), 112001–10pp.
Abstract: A highly significant structure is observed in the Lambda K-+(c)-pi(+)pi(+) mass spectrum, where the Lambda(+)(c) baryon is reconstructed in the decay mode pK(-)pi(+). The structure is consistent with originating from a weakly decaying particle, identified as the doubly charmed baryon Xi(++)(cc). The difference between the masses of the Xi(++)(cc) and Lambda(+)(c) states is measured to be 1334.94 +/- 0.72(stat.) +/- 0.27(syst.) MeV/c(2), and the Xi(++)(cc) mass is then determined to be 3621.40 +/- 0.72(stat.) +/- 0.27(syst.) +/- 0.14(Lambda(+)(c)) MeV/c(2), where the last uncertainty is due to the limited knowledge of the Lambda(+)(c) mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb(-1), and confirmed in an additional sample of data collected at 8 TeV.
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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). Prompt and nonprompt J/psi production and nuclear modification in pPb collisions at root s(NN)=8.16 TeV. Phys. Lett. B, 774, 159–178.
Abstract: The production of J/psi mesons is studied in proton-lead collisions at the centre-of-mass energy per nucleon pair root s(NN) = 8.16 TeV with the LHCb detector at the LHC. The double differential cross-sections of prompt and nonprompt J/psi production are measured as a function of the J/psi transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame. Forward-to-backward ratios and nuclear modification factors are determined. The results are compared with theoretical calculations based on collinear factorisation using nuclear parton distribution functions, on the colour glass condensate or on coherent energy loss models.
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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). Model-Independent Observation of Exotic Contributions to B degrees -> J/psi K+pi(-) Decays. Phys. Rev. Lett., 122(15), 152002–10pp.
Abstract: An angular analysis of B degrees -> J/psi K+pi(-) decays is performed, using proton-proton collision data corresponding to an integrated luminosity of 3 fb(-1) collected with the LHCb detector. The m(K+pi(-) ) spectrum is divided into fine bins. In each m(K+pi(-)) bin, the hypothesis that the three-dimensional angular distribution can be described by structures induced only by K* resonances is examined, making minimal assumptions about the K+pi(-) system. The data reject the K*-only hypothesis with a large significance, implying the observation of exotic contributions in a model-independent fashion. Inspection of the m(J/psi pi(-)) vs m(K+pi(-)) plane suggests structures near m(J/psi pi(-)) = 4200 and 4600 MeV.
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