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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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Observation of the doubly Cabibbo-suppressed decay Xi(+)(c) -> p phi. J. High Energy Phys., 04(4), 084–18pp.
Abstract: The doubly Cabibbo- suppressed decay Xi(+)(c) -> p phi with ! K+K is observed for the fi rst time, with a statistical signi fi cance of more than fi fteen standard deviations. The data sample used in this analysis corresponds to an integrated luminosity of 2 fb recorded with the LHCb detector in pp collisions at a centre- of- mass energy of 8TeV. The ratio of branching fractions between the decay + c ! p and the singly Cabibbo- suppressed decay + c ! pK is measured to be B (Xi(+)(c) -> p phi) B (Xi(+)(c) -> p phi) = (19 : 8 0 : 7 0 : 9 0 : 2) 10 where the fi rst uncertainty is statistical, the second systematic and the third due to the knowledge of the Xi(+)(c) -> pK(+)pi(+) branching fraction.
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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). Search for CP violation through an amplitude analysis of D-0 K+K-+- decays. J. High Energy Phys., 02(2), 126–34pp.
Abstract: A search for CP violation in the Cabibbo-suppressed D-0 K+K-+- decay mode is performed using an amplitude analysis. The measurement uses a sample of pp collisions recorded by the LHCb experiment during 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb(-1). The D-0 mesons are reconstructed from semileptonic b-hadron decays into D0-X final states. The selected sample contains more than 160 000 signal decays, allowing the most precise amplitude modelling of this D-0 decay to date. The obtained amplitude model is used to perform the search for CP violation. The result is compatible with CP symmetry, with a sensitivity ranging from 1% to 15% depending on the amplitude considered.
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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). Measurement of Xi(++)(cc) production in pp collisions at root s=13 TeV. Chin. Phys. C, 44(2), 022001–11pp.
Abstract: The production of Xi(++)(cc) baryons in proton-proton collisions at a centre-of-mass energy of root s = 13 Tev is measured in the transverse-momentum range 4 < p(T) < 15 GeV/c and the rapidity range 2.0 < y < 4.5. The data used in this measurement correspond to an integrated luminosity of 1.7 fb(-1), recorded by the LHCb experiment during 2016. The ratio of the Xi(++)(cc) production cross-section times the branching fraction of the Xi(++)(cc) -> Lambda K-+(c)-pi(+)pi(+) decay relative to the prompt Lambda(+)(c) production cross-section is found to be (2.22 +/- 0.27 +/- 0.29) x 10(-4), assuming the central value of the measured Xi(++)(cc) lifetime, where the first uncertainty is statistical and the second systematic.
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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). Precision measurement of the Xi(++)(cc) mass. J. High Energy Phys., 02(2), 049–18pp.
Abstract: A measurement of the Xi cc++ candidates are reconstructed via the decay modes Xi cc++->?c+K-pi+pi+ and Xi cc++->Xi c+pi+. The result, 3621.55 +/- 0.23 (stat) +/- 0.30 (syst) MeV/c(2), is the most precise measurement of the Xi cc++ mass to date.
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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 doubly charmed baryon Xi(+)(cc). Sci. China-Phys. Mech. Astron., 63(2), 221062–15pp.
Abstract: A search for the doubly charmed baryon.+ cc is performed through its decay to the.+ c K- p+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb-1. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the.+ cc production cross-section times the branching fraction to that of.+ c and.++ cc baryons. The limits are determined as functions of the.+ cc mass for di fferent lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.
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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), 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. (2018). A measurement of the CP asymmetry difference between Lambda(+)(C) -> pK(-)K(+) and p pi(-)pi(+) decays. J. High Energy Phys., 03(3), 182–21pp.
Abstract: The difference between the CP asymmetries in the decays Lambda(+)(C) -> pK(-)K(+) and Lambda(+)(C) -> p pi(-)pi(+) is presented. Proton-proton collision data taken at centre-of-mass energies of 7 and 8 TeV collected by the LHCb detector in 2011 and 2012 are used, corresponding to an integrated luminosity of 3 fb(-1). The Lambda(+)(C) candidates are reconstructed as part of the Lambda(0)(b) -> Lambda(+)(c)mu X- decay chain. In order to maximize the cancellation of production and detection asymmetries in the difference, the final-state kinematic distributions of the two samples are aligned by applying phase-space-dependent weights to the Lambda(+)(C) -> pK(-)K(+) sample. This alters the definition of the integrated CP asymmetry to A(CP)(wgt)(p pi(-)pi(+)). Both samples are corrected for reconstruction and selection efficiencies across the five-dimensional Lambda(+)(C) decay phase space. The difference in CP asymmetries is found to be Delta A(CP)(wgt) = A(CP)(pK(-)K(+)) – A(CP)(wgt)(p pi(-)pi(+)) = (0.30 +/- 0.91 +/- 0.61) %, where the first uncertainty is statistical and the second is systematic.
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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 D-s(+/-) production asymmetry in pp collisions at root s=7 and 8 TeV. J. High Energy Phys., 08(8), 008–21pp.
Abstract: The inclusive D-s(+/-) production asymmetry is measured in pp collisions collected by the LHCb experiment at centre-of-mass energies of root s = 7 and 8 TeV. Promptly produced D-s(+/-) mesons are used, which decay as D-s(+/-) -> phi pi(+/-), with phi -> K+ K-. The measurement is performed in bins of transverse momentum, pT, and rapidity, y, covering the range 2.5 < pT < 25 : 0 GeV/c and 2.0 < y < 4.5. No kinematic dependence is observed. Evidence of nonzero D-s(+/-) production asymmetry is found with a significance of 3.3 standard deviations.
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