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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2024). Study of Bc+ → χc π+ decays. J. High Energy Phys., 02(2), 173–30pp.
Abstract: A study of B-c(+) -> chi(c) pi(+) decays is reported using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV, corresponding to an integrated luminosity of 9 fb(-1). The decay B-c(+) -> chi(c2)pi(+) is observed for the first time, with a significance exceeding seven standard deviations. The relative branching fraction with respect to the B-c(+) -> J/psi pi(+) decay is measured to be BBc+ ->chi c2 pi+/BBc+ -> (J/psi pi+) = 0.37 +/- 0.06 +/- 0.02 +/- 0.01, where the first uncertainty is statistical, the second is systematic, and the third is due to the knowledge of the chi(c2) -> J/psi gamma branching fraction. No significant B-c(+) -> chi(+)(c1 pi) signal is observed and an upper limit for the relative branching fraction for the B-c(+) -> chi(c1)pi(+) and B-c(+) -> chi(c2)pi(+) decays of BBc+ ->chi c1 pi+/BBc+ -> chi(c2)pi(+) < 0.49 is set at the 90% confidence level.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2021). Angular analysis of the rare decay B-s(0) -> phi mu(+)mu(-). J. High Energy Phys., 11(11), 043–45pp.
Abstract: An angular analysis of the rare decay B-s(0) -> phi mu(+)mu(-) is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, corresponding to an integrated luminosity of 8.4 fb(-1). The observables describing the angular distributions of the decay B-s(0) -> phi mu(+)mu(-) are determined in regions of q(2), the square of the dimuon invariant mass. The results are consistent with Standard Model predictions.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2021). Observation of a Lambda(0)(b) – (Lambda)over-bar(b)(0) production asymmetry in proton-proton collisions at root s=7 and 8 TeV. J. High Energy Phys., 10(10), 060–38pp.
Abstract: This article presents differential measurements of the asymmetry between Lambda(0)(b) and (Lambda) over bar (0)(b) baryon production rates in proton-proton collisions at centre-of-mass energies of root s = 7 and 8 TeV collected with the LHCb experiment, corresponding to an integrated luminosity of 3 fb(-1). The Lambda(0)(b) baryons are reconstructed through the inclusive semileptonic decay Lambda(0)(b) -> Lambda(+)(c) mu(-)(nu) over bar X-mu. The production asymmetry is measured both in intervals of rapidity in the range 2:15 < y < 4:10 and transverse momentum in 2 < p T < 27 GeV/c. The results are found to be incompatible with symmetric production with a significance of 5.8 standard deviations for both root s = 7 and 8 TeV data, assuming no CP violation in the decay. There is evidence for a trend as a function of rapidity with a significance of 4 standard deviations. Comparisons to predictions from hadronisation models in Pythia and heavy-quark recombination are provided. This result constitutes the first observation of a particle-antiparticle asymmetry in b-hadron production at LHC energies.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2021). Simultaneous determination of CKM angle gamma and charm mixing parameters. J. High Energy Phys., 12(12), 141–32pp.
Abstract: A combination of measurements sensitive to the CP violation angle gamma of the Cabibbo-Kobayashi-Maskawa unitarity triangle and to the charm mixing parameters that describe oscillations between D-0 and (D) over bar (0) mesons is performed. Results from the charm and beauty sectors, based on data collected with the LHCb detector at CERN's Large Hadron Collider, are combined for the first time. This method provides an improvement on the precision of the charm mixing parameter y by a factor of two with respect to the current world average. The charm mixing parameters are determined to be x = (0.400(-0.053)(+0.052))% and y = (0.630(-0.030)(+0.033))%. The angle gamma is found to be gamma = (65.4(-4.2)(+3.8))degrees and is the most precise determination from a single experiment.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2021). Updated search for B-c(+) decays to two charm mesons. J. High Energy Phys., 12(12), 117–23pp.
Abstract: A data set corresponding to an integrated luminosity of 9 fb(-1) of proton-proton collisions collected by the LHCb experiment has been analysed to search for D-(s)(()*())+ ((D) over bar)(*)0 decays. The decays are fully or partially reconstructed, where one or two (8) missing neutral pions or photons from the decay of an excited charm meson are allowed. Upper limits for the branching fractions, normalised to B+ decays to final states with similar topologies, are obtained for sixteen B-c(+) decay modes. For the decay B-c(+) -> D-s(+)(D) over bar (0), an excess with a significance of 3.4 standard deviations is found.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Constraints on the CKM angle gamma from B-+/- -> Dh(+/-) decays using D -> h(+/-)h '(-/+)pi(0) final states. J. High Energy Phys., 07(7), 099–24pp.
Abstract: A data sample collected with the LHCb detector corresponding to an integrated luminosity of 9 fb(-1) is used to measure eleven CP violation observables in B-+/- -> Dh(+/-) decays, where h is either a kaon or a pion. The neutral D meson decay is reconstructed in the three-body final states: K-+/-pi(-/+)pi(0); pi(+)pi(-)pi(0); K+ K- pi(0) and the suppressed pi K-+(-/+)pi(0) combination. The mode where a large CP asymmetry is expected, B-+/- -> [K-+/-pi(-/+)pi(0)] K-D(+/-), is observed with a significance greater than seven standard deviations. The ratio of the partial width of this mode relative to that of the favoured mode, B-+/- -> [K-+/-pi(-/+)pi(0)] K-D(+/-), is R-ADS(K) = (1.27 +/- 0.16 +/- 0.02) x 10(-2). Evidence for a large CP asymmetry is also seen: A(ADS(K)) = – 0.38 +/- 0.12 +/- 0.02. Constraints on the CKM angle gamma are calculated from the eleven reported observables.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Observation of Lambda b(0) -> D(+)p pi(-)pi(-) and Lambda b(0) -> D-*+p pi(-)pi(-) decays. J. High Energy Phys., 03(3), 153–30pp.
Abstract: The multihadron decays Lambda(0)(b) -> D(+)p pi(-)pi(-) and Lambda(0 )(b)-> D-*+p pi(-)pi(-) are observed in data corresponding to an integrated luminosity of 3fb(-1), collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay Lambda(0)(b) -> Lambda(+)(c)pi(+)pi(-)pi(-) as a normalisation channel, the ratio of branching fractions is measured to be B(Lambda(0)(b) -> D(+)p pi(-)pi(-))/B(Lambda(0)(b) -> Lambda(+)(c)pi(+)pi(-)pi(-)) x B(D+ -> K-pi(+)pi(+))/B(Lambda(+)(c)-> pK(-)pi(+)) = (5.35 +/- 0.21 +/- 0.16) %, where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the Lambda(0)(b)-> D-*+p pi(-)pi(-) and Lambda(0)(b) -> D(+)p pi(-)pi(-) decays is found to be B(Lambda(0)(b)-> D-*+p pi(-)pi(-))/B(Lambda(0)(b) -> D(+)p pi(-)pi(-)) x (B(D-*+-> D+pi(0)) + B(D (*)+-> D- (+)gamma)) = (61.3 +/- 4.3 +/- 4.0) %.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Search for the decay B-0 -> phi mu(+) mu(-). J. High Energy Phys., 05(5), 067–21pp.
Abstract: A search for the decay B-0 -> phi mu(+) mu(-) is performed using proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV collected by the LHCb experiment and corresponding to an integrated luminosity of 9 fb(-1). No evidence for the B-0 -> phi mu(+) mu(-) decay is found and an upper limit on the branching fraction, excluding the 0 and charmonium regions in the dimuon spectrum, of 4.4 x 10(-3) at a 90% credibility level, relative to that of the B-s(0) -> phi mu(+) mu(-) decay, is established. Using the measured B-s(0) -> phi mu(+) mu(-) branching fraction and assuming a phase-space model, the absolute branching fraction of the decay B-0 -> phi mu(+) mu(-) in the full q(2) range is determined to be less than 3.2 x 10(-9) at a 90% credibility level.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Search for the radiative Xi(-)(b) -> Xi(-)gamma decay. J. High Energy Phys., 01(1), 069–20pp.
Abstract: The first search for the rare radiative decay Xi(-)(b) -> Xi(-)gamma is performed using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.4 fb(-1). The Xi(-)(b) -> Xi(-)-J/ psi channel is used as normalization. No Xi(-)(b) -> Xi(-)gamma signal is found and an upper limit of B(Xi(-)(b) -> Xi(-)gamma) < 1.3 x 10(-4) at 95% confidence level is obtained.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Searches for rare B-s(0) and B-0 decays into four muons. J. High Energy Phys., 03(3), 109–27pp.
Abstract: Searches for rare B-s(0) and B-0 decays into four muons are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1). Direct decays and decays via light scalar and J/psi resonances are considered. No evidence for the six decays searched for is found and upper limits at the 95% confidence level on their branching fractions ranging between 1.8 x 10(-10) and 2.6 x 10(-9) are set.
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