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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). Evidence for the Rare Decay Sigma(+) -> p mu(+)mu(-). Phys. Rev. Lett., 120(22), 221803–10pp.
Abstract: A search for the rare decay Sigma(+) -> p mu(+)mu(-) is performed using pp collision data recorded by the LHCb experiment at center-of-mass energies root s = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). An excess of events is observed with respect to the background expectation, with a signal significance of 4.1 standard deviations. No significant structure is observed in the dimuon invariant mass distribution, in contrast with a previous result from the HyperCP experiment. The measured Sigma(+) -> p mu(+)mu(-) branching fraction is (2.2(-1.3)(+1.8)) x 10(-8), where statistical and systematic uncertainties are included, which is consistent with the standard model prediction.
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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). Observation of the decay B-s(0) -> phi pi(+)pi(-) and evidence for B-0 -> phi pi(+)pi(-). Phys. Rev. D, 95(1), 012006–15pp.
Abstract: The first observation of the rare decay B-s(0) -> phi pi(+) pi(-) and evidence for B-0 -> phi pi(+) pi(-) are reported, using pp collision data recorded by the LHCb detector at center-of-mass energies root s = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). The branching fractions in the pi(+) pi(-) invariant mass range 400 < m(pi(+) pi(-)) < 1600 MeV/c(2) are [3.48 +/- 0.23 +/- 0.17 +/- 0.35 +/- x 10(-6)] and [1.82 +/- 0.25 +/- 0.41 +/- 0.14 +/- x 10(-7) for B-s(0) -> phi pi(+) pi(-) and B-0 -> phi pi(+) pi(-) respectively, where the uncertainties are statistical, systematic and from the normalization mode B-s(0)-> phi phi. A combined analysis of the pi(+) pi(-) mass spectrum and the decay angles of the final-state particles identifies the exclusive decays B-s(0) -> phi f(0)(980), B-s(0) -> phi f(2)(1270), and B-s(0) -> phi rho(0) with branching fractions of [1.12 +/- 0.16(-0.08)(+0.09) +/- 0.11] x 10(-6), [0.61 +/- 0.13(-0.05)(+0.12) +/- 0.06] x 10-6 and [2.7 +/- 0.7 +/- 0.2 +/- 0.2] x 10(-7), 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). Measurement of the CP Violation Parameter A(r) in D-0 -> K+K- and D-0 -> pi(+)pi(-) Decays. Phys. Rev. Lett., 118(26), 261803–9pp.
Abstract: Asymmetries in the time-dependent rates of D-0 -> K+K- and D-0 -> pi(+)pi(-)decays are measured in a pp collision data sample collected with the LHCb detector during LHC Run 1, corresponding to an integrated luminosity of 3 fb(-1). The asymmetries in effective decay widths between D-0 and (D) over bar (0) decays, sensitive to indirect CP violation, are measured to be A(r)(K+K-) = (-0.30 +/- 0.32 0.10) x 10(-3) and A(r) pi(+)pi(-)) = (0.46 +/- 0.58 +/- 0.12) x 10(-3), where the first uncertainty is statistical and the second systematic. These measurements show no evidence for CP violation and improve on the precision of the previous best measurements by nearly a factor of two.
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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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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Near-threshold DD spectroscopy and observation of a new charmonium state. J. High Energy Phys., 07(7), 035–23pp.
Abstract: Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb, collected with the LHCb detector between 2011 and 2018, a new narrow charmonium state, the X(3842) resonance, is observed in the decay modes X(3842) ! D0 D 0 and X(3842) ! D+D. The mass and the natural width of this state are measured to be where the fi rst uncertainty is statistical and the second is systematic. The observed mass and narrow natural width suggest the interpretation of the new state as the unobserved spin-3 3 1 3 D 3 charmonium state. In addition, prompt hadroproduction of the (3770) and 2 (3930) states is observed for the fi rst time, and the parameters of these states are measured to be m (3770) = 3778 : 1 0 : 7 0 : 6MeV where the first uncertainty is statistical and the second is systematic.
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