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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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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), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Search for CP violation in D-(s)(+) -> h(+) pi(0) and decays D-(s)(+) -> h(+) eta decays. J. High Energy Phys., 06(6), 019–25pp.
Abstract: Searches for CP violation in the two-body decays D-(s)(+) -> h(+)pi(0) and D-(s)(+) -> h(+)eta (where h(+) denotes a pi(+) or K+ meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb(-1) or 6 fb(-1) of integrated luminosity. The pi(0) and eta mesons are reconstructed using the e(+) e(-)gamma final state, which can proceed as three-body decays pi(0) -> e(+) e(-) gamma and eta -> e(+) e(-)gamma, or via the two-body decays pi(0) -> gamma gamma and eta -> gamma gamma followed by a photon conversion. The measurements are made relative to the control modes D-(s)(+) K(S)(0)h(+) to cancel the production and detection asymmetries. The CP asymmetries are measured to be A(CP)(D+ -> pi(+)pi(0)) = (-1.3 +/- 0.9 +/- 0.6)%, A(CP)(D+ -> K+pi(0)) = (- 3.2 +/- 4.7 +/- 2.1)%, A(CP)(D+ -> pi(+)eta) = (-0.2 +/- 0.8 +/- 0.4)%, A(CP)(D+ -> K+eta) = (-6 +/- 10 +/- 4 )%, A(CP)(D-s(+) -> K+pi(0)) = (-0.8 +/- 3.9 +/- 1.2)%, A(CP)(D-s(+) -> pi(+)eta) = ( 0.8 +/- 0.7 +/- 0.5)%, A(CP)(D-s(+) -> K+eta) = ( 0.9 +/- 3.7 +/- 1.1)%, where the first uncertainties are statistical and the second systematic. These results are consistent with no CP violation and mostly constitute the most precise measurements of A(CP) in these decay modes to date.
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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 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., 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. (2019). A search for Xi(++)(cc) -> D(+)pK(-)pi(+) decays. J. High Energy Phys., 10(10), 124–21pp.
Abstract: A search for the Xi(++)(cc) baryon through the Xi(++)(cc) -> D(+)pK(-)pi(+) decay is performed with a data sample corresponding to an integrated luminosity of 1.7 fb(-1) recorded by the LHCb experiment in pp collisions at a centre-of-mass energy of 13 TeV. No significant signal is observed in the mass range from the kinematic threshold of the decay to 3800 MeV/c(2). An upper limit is set on the ratio of branching fractions R = B(Xi(++)(cc) -> D(+)pK(-)pi(+))/B(Xi(++)(cc) -> A(c)(+) K- pi(+)pi(+)) with R < 1.7 (2.1) x 10(-2) at the 90% (95%) confidence level at the known mass of the Xi(++)(cc) state.
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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). Measurements of the branching fractions of Lambda(+)(c) -> p pi(-)pi(+), Lambda(+)(c) -> pK(-)K(+), and Lambda(+)(c) -> p pi K-(+). J. High Energy Phys., 03(3), 043–23pp.
Abstract: The ratios of the branching fractions of the decays do Lambda(+)(c) -> , p pi(-)pi(+), Lambda(+->)(c) pK(-)K(+), and Lambda(+)(c) -> p pi K--(+) with respect to the Cabibbo-favoured Lambda(+)(c) -> pK(-)pi(+) decay are measured using proton-proton collision data collected with the LHCb experiment at a 7 TeV centre-of-mass energy and corresponding to an integrated luminosity of 1.0 fb(-1): B(Lambda(+)(c) -> p pi(-)pi(+))/B(Lambda(+)(c) -> pK(-)pi(+)) = (7.44 +/- 0.08 +/- 0.18)%. B(Lambda(+)(c) -> pK(-)K(+))/B(Lambda(+)(c) -> pK(-)pi(+) = (1.70 +/- 0.03 +/- 0.03)%, B(Lambda(+)(c) -> p pi(-)pi K-+(+))/B(Lambda(+)(c) -> pK(-)pi(+) = (0.165 +/- 0.015 +/- 0.005)%, where the uncertainties are statistical and systematic, respectively. These results are the most precise measurements of these quantities to date. When multiplied by the world average value for B(Lambda(+)(c) -> p pi(-)pi(+)), the corresponding branching fractions are B(Lambda(+)(c) -> p pi(-)pi(+) = (4.72 +/- 0.05 +/- 0.11 +/- 0.25) x 10(-3), B(Lambda(+)(c) -> pK(-)K(+)) = (1.08 +/- 0.02 +/- 0.02 +/- 0.06) x 10(-3), B(Lambda(+)(c) -> , p pi K--(+)) = (1.04 +/- 0.09 +/- 0.03 +/- 0.05) x 10(-4), where the final uncertainty is due to B(Lambda(+)(c) -> pK(-)pi(+)).
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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. (2019). Measurement of the branching fractions of the decays D+ -> K-K+K+, D+ -> pi-pi(+) K+ and D-s(+) -> pi-K+K+. J. High Energy Phys., 03(3), 176–24pp.
Abstract: The branching fractions of the doubly Cabibbo-suppressed decays D+ ! K, D+ ! and D+ s ! are measured using the decays D+ ! K and D+ s ! K as normalisation channels. The measurements are performed using proton-proton collision data collected with the LHCb detector at a centre-of-mass energy of 8TeV, corresponding to an integrated luminosity of 2.0 fb. The results are B (D+ ! K) B (D+ ! K) = (6 : 541 0 : 025 0 : 042) 10 B (D+ ! ) B (D+ ! K) = (5 : 231 0 : 009 0 : 023) 10 B (D+ s ! ) B (D+ s ! K) = (2 : 372 0 : 024 0 : 025) 10 where the uncertainties are statistical and systematic, respectively. These are the most precise measurements up to date.
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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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