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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 the rare decay B-0 -> J/psi phi. Chin. Phys. C, 45(4), 043001–14pp.
Abstract: A search for the rare decay B-0 -> J/psi phi, is performed using pp collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). No significant signal of the decay is observed and an upper limit of 1.1 x 10(-7) at 90% confidence level is set on the branching fraction.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Vidal, J., et al. (2023). Nuclear Modification Factor of Neutral Pions in the Forward and Backward Regions in p-Pb Collisions. Phys. Rev. Lett., 131(4), 042302–12pp.
Abstract: The nuclear modification factor of neutral pions is measured in proton-lead collisions collected at a center-of-mass energy per nucleon of 8.16 TeV with the LHCb detector. The p(0) production cross section is measured differentially in transverse momentum (p(T)) for 1.5 < p(T) < 10.0 GeV and in center-of-mass pseudorapidity (?(c.m.)) regions 2.5 < ?(c.m.) < 3.5 (forward) and -4.0 < ?(c.m.) < -3.0 (backward) defined relative to the proton beam direction. The forward measurement shows a sizable suppression of p(0) production, while the backward measurement shows the first evidence of p(0) enhancement in proton-lead collisions at the LHC. Together, these measurements provide precise constraints on models of nuclear structure and particle production in high-energy nuclear 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). First Observation of a Doubly Charged Tetraquark and Its Neutral Partner. Phys. Rev. Lett., 131(4), 041902–12pp.
Abstract: A combined amplitude analysis is performed for the decays B0-+ D0D thorn s & pi;- and B thorn -+ D-D thorn s & pi; thorn , which are related by isospin symmetry. The analysis is based on data collected by the LHCb detector in proton -proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. Two new resonant states with masses of 2.908 ⠂ 0.011 ⠂ 0.020 GeV and widths of 0.136 ⠂ 0.023 ⠂ 0.013 GeV are observed, which decay to D thorn s & pi; thorn and D thorn s & pi;- respectively. The former state indicates the first observation of a doubly charged open-charm tetraquark state with minimal quark content 1/2cs over bar ud over bar ⠃, and the latter state is a neutral tetraquark composed of 1/2cs over bar u over bar d ⠃ quarks. Both states are found to have spin-parity of 0 thorn , and their resonant parameters are consistent with each other, which suggests that they belong to an isospin triplet.
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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 Rare Decays of D0 Mesons into Two Muons. Phys. Rev. Lett., 131(4), 041804–13pp.
Abstract: A search for the very rare D-0 -> mu(+)mu(-) decay is performed using data collected by the LHCb experiment in proton-proton collisions at root s = 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). The search is optimized for D-0 mesons from D*(+) -> D-0 pi(+) decays but is also sensitive to D-0 mesons from other sources. No evidence for an excess of events over the expected background is observed. An upper limit on the branching fraction of this decay is set at B(D-0 -> mu(+)mu(-)) < 3.1 x 10(-9) at a 90% C.L. This represents the world's most stringent limit, constraining models of physics beyond the standard model.
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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). First Observation of a Baryonic B-s(0) Decay. Phys. Rev. Lett., 119(4), 041802–10pp.
Abstract: We report the first observation of a baryonic B-s(0) decay, B-s(0). p (Lambda) over barK(-), using proton-proton collision data recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0 fb(-1). The branching fraction is measured to be B(B-s(0) -> p (Lambda) over bar K-)+ B(B-s(0) -> p (Lambda) over bar K+) [5.46 +/- 0.61 +/- 0.57 +/- 0.50(B) +/- 0.32(f(s)/(d))] x 10(-6), where the first uncertainty is statistical and the second systematic, the third uncertainty accounts for the experimental uncertainty on the branching fraction of the B-0 -> p (Lambda) over bar pi(-) decay used for normalization, and the fourth uncertainty relates to the knowledge of the ratio of b-quark hadronization probabilities f(s)/f(d).
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