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 Υ production in pp collisions at √s=5 TeV. J. High Energy Phys., 07(7), 069–33pp.
Abstract: The production cross-sections of Υ mesons, namely Υ(1S), Υ(2S) and Υ(3S), in pp collisions at root s = 5TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 +/- 0.18 pb(-1) collected by the LHCb detector. The Υ mesons are reconstructed in the decay mode Υ -> mu(+)mu(-). Double differential cross-sections times branching fractions, as functions of the transverse momentum p(T) and the rapidity y of the Υ mesons, are measured in the range pT < 20 GeV/ c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are sigma((sic)(1S)) x B((sic)(1S) -> mu(+) mu(-)) = 2101 +/- 33 +/- 83 pb, sigma((sic)(2S)) x B((sic)(2S) -> mu(+) mu(-)) = 526 +/- 20 +/- 21 pb, sigma((sic)(3S)) x B((sic)(3S) -> mu(+) mu(-)) = 242 +/- 16 +/- 10 pb, where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different (sic) states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of (sic)(1S) at root s = 5TeV is updated as well using the directly measured cross-section results from this analysis.
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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). Study of the psi(2)(3823) and chi(c1)(3872) states in B+->(J/psi pi(+)pi(-))K(+)decays. J. High Energy Phys., 08(8), 123–29pp.
Abstract: The decays B+-> J/psi pi(+)pi(-)K(+)are studied using a data set corresponding to an integrated luminosity of 9 fb(-1)collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate psi(2)(3823), chi(c1)(3872) and psi(2S) states are reported. The values areBB+->psi 2(“>3823K+xB psi 2(”>3823 -> J/psi pi+pi-BB+->chi c1>3872K+xB chi c1>3872 -> J/psi pi+pi-=>3.56 +/- 0.67 +/- 0.11x10-2,BB+->psi 2>3823K+xB psi 2>3823 -> J/psi pi+pi-BB+->psi>2SK+xB psi>2S -> J/psi pi+pi-=>1.31 +/- 0.25 +/- 0.04x10-3,BB+->chi c1>3872K+xB chi c1>3872 -> J/psi pi+pi-BB+->psi>2SK+xB psi>2S -> J/psi pi+pi-= where the first uncertainty is statistical and the second is systematic. The decay of B+->psi(2)(3823)K(+)with psi(2)(3823)-> J/psi pi(+)pi(-)is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the psi(2)(3823), chi(c1)(3872) and psi(2S) states are measured to be m chi c1>3872-m psi 2>3823=47. 50 +/- 0.53 +/- 0.13MeV/c2,m psi 2 2S=185.49 +/- 0.06 +/- 0.03MeV/c2, resulting in the most precise determination of the chi(c1)(3872) mass. The width of the psi(2)(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the chi(c1)(3872) state is measured to be Gamma chi c13872BW=0.96-0.18+0.19 +/- 0.21MeV={0.96}_{-0.18}<^>{+0.19}\pm 0.21\;\mathrm{MeV} which is inconsistent with zero by 5.5 standard deviations.
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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 doubly heavy baryons Omega(0)(bc) and Xi(0)(bc) decaying to Lambda(+)(c)pi(-) and Xi(+)(c)pi-. Chin. Phys. C, 45(9), 093002–12pp.
Abstract: The first search for the doubly heavy Omega(0)(bc) baryon and a search for the Xi(0)(bc) baryon are performed using collision data collected via the experiment from 2016 to 2018 at a centre-of-mass energy of, corresponding to an integrated luminosity of 5.2 fb(-1). The baryons are reconstructed via their decays to Lambda(+)(-)(c)(pi) and Xi(+)(c)pi(-). No significant excess is found for invariant masses between 6700 and 7300 MeV/c(2), in a rapidity range from 2.0 to 4.5 and a transverse momentum range from 2 to 20 MeV/c. Upper limits are set on the ratio of the Omega(0)(bc) and Xi(0)(bc) production cross-section times the branching fraction to Lambda(+)(c)pi(-)(Xi(+)(c)pi(-)) relative to that of the Lambda(0)(b)(Xi(0)(b)) baryon, for different lifetime hypotheses, at 95% confidence level. The upper limits range from 0.5x10(-4) to 2.5x10(-4) for the Omega(0)(bc) -> Lambda(+)(c)pi(-) (Xi(0)(bc) -> Lambda(+)(c)pi(-)) decay, pending on the considered mass and lifetime of the Omega(0)(bc) (Xi(0)(bc)) baryon.
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