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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., Ferrer, A., et al. (2014). Measurement of the production of a W boson in association with a charm quark in pp collisions at root s=7 TeV with the ATLAS detector. J. High Energy Phys., 05(5), 068–67pp.
Abstract: The production of a W boson in association with a single charm quark is studied using 4.6 fb(-1) of pp collision data at root s = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96(-0.30)(+0.26) at Q (2) = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio sigma(W (+) +)/sigma(W (-) + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s-(s) over bar quark asymmetry.
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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). Study of the D(0)p amplitude in Lambda(0)(b) -> D(0)p pi(-) decays. J. High Energy Phys., 05(5), 030–43pp.
Abstract: An amplitude analysis of the decay Lambda(0)(b) -> D(0)p pi(-) is performed in the part of the phase space containing resonances in the D(0)p channel. The study is based on a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions recorded by the LHCb experiment. The spectrum of excited Lambda(+)(c) states that decay into D(0)p is studied. The masses, widths and quantum numbers of the Lambda(c)(2880)(+) and Lambda(c) (2940)(+) resonances are measured. The constraints on the spin and parity for the Lambda(c)(2940)(+) state are obtained for the first time. A near-threshold enhancement in the D(0)p amplitude is investigated and found to be consistent with a new resonance, denoted the Lambda(c) (2860)(+), of spin 3/2 and positive parity.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Vidal, J., et al. (2022). Observation of the doubly charmed baryon decay Xi(++)(cc) -> Xi(c)'(+)pi(+). J. High Energy Phys., 05(5), 038–18pp.
Abstract: The Xi(++)(cc) -> Xi('+)(c)pi(+) decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb(-1). The Xi(++)(cc) -> Xi('+)(c)pi(+) decay is reconstructed partially, where the photon from the Xi('+)(c) -> Xi(+)(c)gamma decay is not reconstructed and the pK(-)pi(+) final state of the Sc+ baryon is employed. The Xi(++)(cc) -> Xi('+)(c)pi(+) branching fraction relative to that of the Xi(++)(cc) -> Xi('+)(c)pi(+) decay is measured to be 1.41 +/- 0.17 +/- 0.10, where the first uncertainty is statistical and the second systematic.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Measurement of indirect CP asymmetries in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays using semileptonic B decays. J. High Energy Phys., 04(4), 043–19pp.
Abstract: Time-dependent CP asymmetries in the decay rates of the singly Cabibbo-suppressed decays D-0 -> K-K+ and D-0 -> pi (-) pi(+) are measured in pp collision data corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb experiment. The D-0 mesons are produced in semileptonic b-hadron decays, where the charge of the accompanying muon is used to determine the initial state as D-0 or (D) over bar (0). The asymmetries in effective lifetimes between D-0 and (D) over bar (0) decays, which are sensitive to indirect CP violation, are determined to be A(Gamma) (K-K+) = (-0.134 +/- 0.077(-0.034)(+0.026))%, A(Gamma) (pi(-)pi(+)) = -0.092 +/- 0.145(-0.033)(+0.025))%, where the first uncertainties are statistical and the second systematic. This result is in agreement with previous measurements and with the hypothesis of no indirect CP violation in D (0) decays.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Model-independent measurement of mixing parameters in D-0 -> K-S(0)pi(+)pi(-) decays. J. High Energy Phys., 04(4), 033–26pp.
Abstract: The first model-independent measurement of the charm mixing parameters in the decay D-0 -> K-S(0)pi(+)pi(-) is reported, using a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb(-1) at a centre-of-mass energy of 7 TeV. The measured values are x = (0.86 +/- 0.53 +/- 0.17) x 10(-2), y = (+0.03 +/- 0.46 +/- 0.13) x 10(-2), where the first uncertainties are statistical and include small contributions due to the external input for the strong phase measured by the CLEO collaboration, and the second uncertainties are systematic.
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