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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Search for Higgs-like bosons decaying into long-lived exotic particles. Eur. Phys. J. C, 76(12), 664–15pp.
Abstract: A search is presented for massive long-lived particles, in the 20-60 GeV/c(2) mass range with lifetimes between 5 and 100 ps. The dataset used corresponds to 0.62 fb(-1) of proton-proton collision data collected by the LHCb detector at root s = 7 TeV. The particles are assumed to be pair-produced by the decay of a Higgs-like boson with mass between 80 and 140 GeV/c(2). No excess above the background expectation is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime and of the Higgs-like boson mass.
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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 massive long-lived particles decaying semileptonically at root s=13 TeV. Eur. Phys. J. C, 82(4), 373–19pp.
Abstract: A search is performed for massive long-lived particles (LLPs) decaying semileptonically into a muon and two quarks. Two kinds of LLP production processes were considered. In the first, a Higgs-like boson with mass from 30 to 200 GeV/c(2) is produced by gluon fusion and decays into two LLPs. The analysis covers LLP mass values from 10 GeV/c(2) up to about one half the Higgs-like boson mass. The second LLP production mode is directly from quark interactions, with LLP masses from 10 to 90 GeV/c(2). The LLP lifetimes considered range from 5 to 200 ps. This study uses LHCb data collected from proton-proton collisions at root s = 13 TeV, corresponding to an integrated luminosity of 5.4 fb(-1). No evidence of these long-lived states has been observed, and upper limits on the production cross-section times branching ratio have been set for each model considered.
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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). Observation of Λb0 → Λc+ (D)over-bar(*)0 K- and Λb0 → Λc+ Ds*- decays. Eur. Phys. J. C, 84(6), 575–18pp.
Abstract: The decays Lambda(0)(b) -> Lambda(+)(c) (D) over bar (()*()0) K- and Lambda(0)(b) -> Lambda(+)(c) D-s*(-) are observed for the first time, in proton-proton collision data at root s = 13TeV, corresponding to an integrated luminosity of 5.4fb(-1) collected with the LHCb detector. Their ratios of branching fractions with respect to the Lambda(0)(b) -> Lambda(+)(c) D-s(-) mode are measured to be B(Lambda(0)(b) -> Lambda(+)(c) (D) over bar (0) K-)/B(Lambda(0)(b) -> Lambda(+)(c) D-s(-)) = 0.1908(-0.0034-0.0018)(+0.0036+0.0016) +/- 0.0038, B(Lambda(0)(b) -> Lambda(+)(c) (D) over bar*(0) K-)/B(Lambda(0)(b) -> Lambda(+)(c) D-s(-)) = 0.589(-0.017-0.018)(+0.018+0.017) +/- 0.012, B(Lambda(0)(b) -> Lambda(+)(c) D-s*(-))/B(Lambda(0)(b) -> Lambda(+)(c) D-s(-)) = 1.668 +/- 0.022(-0.055)(+0.061), where the first uncertainties are statistical, the second systematic, and the third, for the Lambda(0)(b) -> Lambda(+)(c) (D) over bar (()*()0) K- decays, are due to the uncertainties on the branching fractions of the D-s(-) -> K- K+ pi(-) and (D) over bar0 -> K+ pi(-) decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in Lambda(0)(b) -> Lambda(+)(c) (D) over bar (()*()0) K- decay channels.
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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). Observation of Ξb0→ Ξc + Ds- and Ξb0 c D- s decays. Eur. Phys. J. C, 84(3), 237–17pp.
Abstract: The Ξ0b→Ξ+cD−s and Ξ−b→Ξ0cD−s decays are observed for the first time using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of s√=13TeV, corresponding to an integrated luminosity of 5.1fb−1. The relative branching fractions times the beauty-baryon production cross-sections are measured to be (formula), where the first uncertainties are statistical, the second systematic, and the third due to the uncertainties on the branching fractions of relevant charm-baryon decays. The masses of Ξ0b and Ξ−b baryons are measured to be mΞ0b=5791.12±0.60±0.45±0.24MeV/c2 and mΞ−b=5797.02±0.63±0.49±0.29MeV/c2, where the uncertainties are statistical, systematic, and those due to charm-hadron masses, respectively.
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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). Search for B+c → π+μ+μ- decays and measurement of the branching fraction ratio B(B+c → ψ(2S)π+)/B(B+c< /i> → J/ψπ+). Eur. Phys. J. C, 84(5), 468–17pp.
Abstract: The first search for nonresonant B-c(+) -> pi(+)mu(+)mu(-) decays is reported. The analysis uses proton-proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb(-1). No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio B(B-c(+) -> pi(+)mu(+)mu(-))/B(B-c(+) -> J/psi pi(+)) < 2.1x10(-4) at 90% confidence level. Additionally, an updated measurement of the ratio of the B-c(+) -> psi(2S)pi(+) and B-c(+) -> J/psi pi(+) branching fractions is reported. The ratio B(B-c(+) -> psi(2S)pi+)/B(B-c(+) -> J/psi pi(+)) is measured to be 0.254 +/- 0.018 +/- 0.003 +/- 0.005, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the leptonic J/psi and psi(2S) decays. This measurement is the most precise to date and is consistent with previous LHCb results.
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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). Measurement of the CKM angle γ in the B0 → D K*0 channel using self-conjugate D → KS0 h+ h- decays. Eur. Phys. J. C, 84(2), 206–18pp.
Abstract: A model-independent study of CP violation in B-0 -> DK (*0) decays is presented using data corresponding to an integrated luminosity of 9 fb(-1) collected by the LHCb experiment at centre-of-mass energies of v s = 7, 8 and 13TeV. The CKM angle. is determined by examining the distributions of signal decays in phase-space bins of the self-conjugate D. K(S)(0)h(+) h(-) decays, where h = p, K. Observables related to CP violation are measured and the angle. is determined to be = (49+22 -19). Measurements of the amplitude ratio and strong-phase difference between the favoured and suppressed B-0 decays are also presented.
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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. (2023). Search for D*(2007)0 → μ+ μ- in B- → π- μ+ μ- decays. Eur. Phys. J. C, 83(7), 666–14pp.
Abstract: The very rare D*(2007)(0) -> mu(+) mu(-) decay is searched for by analysing B- -> pi (-) mu(+) mu(-) decays. The analysis uses a sample of beautymesons produced in protonproton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb(-1). The signal signature corresponds to simultaneous peaks in the mu(+) mu(-) and pi(-) mu(+) mu(-) invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at B(D-*(2007)(0) -> mu(+) mu(-)) < 2.6 x 10(-8) at 90% confidence level. This is the first limit on the branching fraction of D*(2007)(0) -> mu(+) mu(-) decays and the most stringent limit on D* (2007)(0) decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.
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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. (2023). J/ψ and D0 production in √s_NN=68.5 GeV PbNe collisions. Eur. Phys. J. C, 83(7), 658–11pp.
Abstract: The firstmeasurement of J/psi and D-0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/psi and D-0 mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of root s(NN) = 68.5 GeV. The J/psi/D-0 production crosssection ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from pNe collisions at the same energy and showno difference in the observed J/psi suppression trend when comparing pNe and PbNe peripheral collisions with PbNe central collisions.
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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. (2023). Measurement of τL using the Bs0 →J/ψη decay mode. Eur. Phys. J. C, 83(7), 629–13pp.
Abstract: Using a proton-proton collision data sample collected by the LHCb detector and corresponding to an integrated luminosity of 5.7 fb(-1), the lifetime of the light B-s(0) mass eigenstate, tau(L), is measured using the B-s(0) -> J/psi eta decay mode to be tau(L) = 1.445 +/- 0.016(stat) +/- 0.008(syst) ps. A combination of this result with a previous LHCb analysis using an independent dataset corresponding to 3 fb(-1) of integrated luminosity gives tau(L) = 1.452 +/- 0.014 +/- 0.007 +/- 0.002 ps, where the first uncertainty is statistical, the second due to the uncorrelated part of the systematic uncertainty and the third due to the correlated part of the systematic uncertainty.
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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. (2023). Charmonium production in pNe collisions at √sNN=68.5 GeV. Eur. Phys. J. C, 83(7), 625–11pp.
Abstract: The measurement of charmonium states produced in proton-neon (pNe) collisions by the LHCb experiment in its fixed-target configuration is presented. The production of J/Psi and Psi(2S) mesons is studied with a beam of 2.5 TeV protons colliding on gaseous neon targets at rest, cvorresponding to a nucleon-nucleon centre-of-mass energy root(NN)-N-s = 68.5GeV. The data sample corresponds to an integrated luminosity of 21.7 +/- 1.4 nb(-1). The J/Psi and Psi(2S) hadrons are reconstructed in mu(+) mu(-) final states. The J/Psi production cross-section per target nucleon in the centre-of-mass rapidity range y* is an element of [-2.29, 0] is found to be 506 +/- 8 +/- 46 nb/nucleon. The ratio of J/Psi and D-0 cross-sections is evaluated to (1.06 +/- 0.02 +/- 0.09)%. The Psi(2S) to J/Psi relative production rate is found to be (1.67 +/- 0.27 +/- 0.10)% in good agreement with other measurements involving beam and target nuclei of similar sizes.
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