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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., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of the relative branching fractions of B+ -> h(+) h('+) h('-) decays. Phys. Rev. D, 102(11), 112010–19pp.
Abstract: The relative branching fractions of B+ -> h(+)h('+)h('-) decays, where h((')) is a pion or kaon, are measured. The analysis is performed with a data sample, collected with the LHCb detector, corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions. The results obtained improve significantly on previous measurements of these quantities, and are important for the interpretation of Dalitz plot analyses of three-body charmless hadronic decays of B+ mesons.
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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). Strong constraints on the b -> s gamma photon polarisation from B-0 -> K(*0)e(+)e(-) decays. J. High Energy Phys., 12(12), 081–25pp.
Abstract: An angular analysis of the B-0 -> K*(0)e(+)e(-) decay is performed using a data sample corresponding to an integrated luminosity of 9 fb(-1) of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared (q(2)) interval between 0.0008 and 0.257 GeV2, where the rate is dominated by the B-0 -> K*(0)gamma transition with a virtual photon. The fraction of longitudinal polarisation of the K*(0) meson, F-L, is measured to be F-L = (4.4 +/- 2.6 +/- 1.4)%, where the first uncertainty is statistical and the second systematic. The A(T)(Re) observable, which is related to the lepton forward-backward asymmetry, is measured to be A(T)(Re) = -0.06 +/- 0.08 +/- 0.02. The A(T)((2)) and A(T)(Im) transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be A(T)((2)) = 0.11 +/- 0.10 +/- 0.02 and A(T)(Im) = 0.02 +/- 0.10 +/- 0.01. The results are consistent with Standard Model predictions and provide the world's best constraint on the b -> s gamma photon polarisation.
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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 heavy Xi bc0 baryon via decays to D(0)pK(-). J. High Energy Phys., 11(11), 095–21pp.
Abstract: A search for the doubly heavy Xi bc0 baryon using its decay to the D(0)pK(-) final state is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb(-1). No significant signal is found in the invariant mass range from 6.7 to 7.2 GeV/c(2). Upper limits are set at 95% credibility level on the ratio of the Xi bc0 production cross-section times its branching fraction to D(0)pK(-) relative to that of the Lambda b0 -> D0pK- decay. The limits are set as a function of the Xi bc0 mass and lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and in the transverse momentum region from 5 to 25 GeV/c. Upper limits range from 1.7 x 10(-2) to 3.0 x 10(-1) for the considered Xi bc0 mass and lifetime hypotheses.
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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). Amplitude analysis of the B+ -> D+D-K+ decay. Phys. Rev. D, 102(11), 112003–32pp.
Abstract: Results are reported from an amplitude analysis of the B+ -> D+D-K+ decay. The analysis is carried out using LHCb proton-proton collision data taken at root s = 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb(-1). In order to obtain a good description of the data, it is found to be necessary to include new spin-0 and spin-1 resonances in the D-K+ channel with masses around 2.9 GeV/c(2), and a new spin-0 charmonium resonance in proximity to the spin-2 chi(c2)(3930) state.
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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). Model-Independent Study of Structure in B+ -> D+D-K+ Decays. Phys. Rev. Lett., 125(24), 242001–10pp.
Abstract: The only anticipated resonant contributions to B+ -> D+D-K+ decays are charmonium states in the D+D- channel. A model-independent analysis, using LHCb proton-proton collision data taken at centerof-mass energies of root s = 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb(-1), is carried out to test this hypothesis. The description of the data assuming that resonances only manifest in decays to the D+D- pair is shown to be incomplete. This constitutes evidence for a new contribution to the decay, potentially one or more new charm-strange resonances in the D-K+ channel with masses around 2.9 GeV/c(2).
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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). First branching fraction measurement of the suppressed decay Xi(0)(c) -> pi(-) Lambda(+)(c). Phys. Rev. D, 102(7), 071101–11pp.
Abstract: The Xi(0)(c) baryon is unstable and usually decays into charmless final states by the c -> sud transition. It can, however, also disintegrate into a pi(-) meson and a Lambda(+)(c) baryon via s quark decay or via cs -> dc weak scattering. The interplay between the latter two processes governs the size of the branching fraction B(Xi(0)(c) -> pi(-) Lambda(+)(c)), first measured here to be (0.55 +/- 0.02 +/- 0.18)%, where the first uncertainty is statistical and second systematic. This result is compatible with the larger of the theoretical predictions that connect models of hyperon decays using partially conserved axial currents and SU(3) symmetry with those involving the heavy-quark expansion and heavy-quark symmetry. In addition, the branching fraction of the normalization channel, B(Xi(+)(c) -> pK(-) pi(+)) = (1.135 +/- 0.002 +/- 0.387)% is measured.
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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). First observation of the decay Lambda(0)(b) -> eta(c) (1S)pK(-). Phys. Rev. D, 102(11), 112012–12pp.
Abstract: The decay Lambda(0)(b) -> eta(c) (1S)pK(- )is observed for the first time using a data sample of proton-proton collisions, corresponding to an integrated luminosity of 5.5 fb I, collected with the LHCb experiment at a center-of-mass energy of 13 TeV. The branching fraction of the decay is measured, using the Lambda(0)(b) -> J/psi pK(-) decay as a normalization mode, to be B(Lambda(0)(b) -> eta(c) (1S)pK(-)) = (1.06 +/- 0.16 +/- 0.06(-019)(+0.22)) x 10(-4), where the quoted uncertainties are statistical, systematic and due to external inputs, respectively. A study of the eta(c)(1S)p mass spectrum is performed to search for the P-c(4312)(+) pentaquark state. No evidence is B(Lambda(0)(b) -> P-c(4312)K-+(-))xB(P-c(4312)(+)-> eta(c)(1S)p)/B(Lambda(0)(b) -> eta(c) (1S)pK(-)) < 0.24( ) observed and an upper limit of < 0.24 is obtained at the 95% confidence level.
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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). Observation of Enhanced Double Parton Scattering in Proton-Lead Collisions at root s(NN)=8.16 TeV. Phys. Rev. Lett., 125(21), 212001–13pp.
Abstract: A study of prompt charm-hadron pair production in proton-lead collisions at root s(NN) = 8.16 TeV is performed using data corresponding to an integrated luminosity of about 30 nb(-1), collected with the LHCb experiment. Production cross sections for different pairs of charm hadrons are measured and kinematic correlations between the two charm hadrons are investigated. This is the first measurement of associated production of two charm hadrons in proton-lead collisions. The results confirm the predicted enhancement of double parton scattering production in proton-lead collisions compared to the single parton scattering production.
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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). First observation of the decay B-0 -> D-0(D)over-bar(0)K(+)pi(-). Phys. Rev. D, 102(5), 051102–11pp.
Abstract: The first observation of the decay B-0 -> D-0(D) over bar K-0(+)pi(-) is reported using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb(-1) collected by the LHCb experiment in 2011, 2012 and 2016. The measurement is performed in the full kinematically allowed range of the decay outside of the D*(-) region. The ratio of the branching fraction relative to that of the control channel B-0 -> D-0<(DK+)-K-0 pi(-)+ is measured to be R = (14.2 +/- 1.1 +/- 1.0)%, where the first uncertainty is statistical and the second is systematic. The absolute branching fraction of B-0 -> D-0(D) over bar K-0(+)pi(- )decays is thus determined to be B(B-0 -> D-0(D) over bar K-0(+)pi(-)) = (3.50 +/- 0.27 +/- 0.26 +/- 0.30) x 10(-4), where the third uncertainty is due to the branching fraction of the control channel. This decay mode is expected to provide insights to spectroscopy and the charm-loop contributions in rare semileptonic decays.
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