LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2022). Study of coherent J/psi production in lead-lead collisions at root S-NN=5 TeV. J. High Energy Phys., 07(7), 117–19pp.
Abstract: Coherent production of J/psi mesons is studied in ultraperipheral lead-lead collisions at a nucleon-nucleon centre-of-mass energy of 5 TeV, using a data sample collected by the LHCb experiment corresponding to an integrated luminosity of about 10 μb(-1). The J/psi mesons are reconstructed in the dimuon final state and are required to have transverse momentum below 1 GeV. The cross-section within the rapidity range of 2.0 < y < 4.5 is measured to be 4.45 +/- 0.24 +/- 0.18 +/- 0.58 mb, where the first uncertainty is statistical, the second systematic and the third originates from the luminosity determination. The cross-section is also measured in J/psi rapidity intervals. The results are compared to predictions from phenomenological models.
|
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.
|
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.
|
LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Observation of a new Xi(0)(b) state. Phys. Rev. D, 103(1), 012004–17pp.
Abstract: Using a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of 8.5 fb(-1), the observation of a new excited Xi(0)(b) resonance decaying to the Xi(-)(b)pi(+) final state is presented. The state, referred to as Xi(b) (6227)(0), has a measured mass and natural width of m(Xi(b)(6227)(0)) = 6227.1(-1.5)(+1.4) +/- 0.5 MeV and Gamma(Xi(b)(6227)(0)) = 18.6(-4.1)(+5.0) +/- 1.4 MeV, where the uncertainties are statistical and systematic. The production rate of the Xi(b)(6227)(0) state relative to that of the Xi(-)(b) baryon in the kinematic region 2 < eta < 5 and p(T) < 30 GeV is measured to be f(Xi b(6227)0)/f(Xi b)(-) B(Xi(b)(6227)(0) -> Xi(-)(b)pi(+)) = 0.045 +/- 0.008 +/- 0.004, where B(Xi(b)(6227)(0) -> Xi(-)(b)pi(+)) is the branching fraction of the decay, and f(Xi b(6227)0) and f(Xi b-) represent fragmentation fractions. Improved measurements of the mass and natural width of the previously observedf Xi(b)(6227)(-) state, along with the mass of the Xi(-)(b) baryon, are also reported. Both measurements are significantly more precise than, and consistent with, previously reported values.
|
LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). First Observation of the Decay B-s(0) -> K-mu(+)nu(mu) and a Measurement of vertical bar V-ub vertical bar/vertical bar V-cb vertical bar. Phys. Rev. Lett., 126(8), 081804–11pp.
Abstract: The first observation of the suppressed semileptonic B-s(0) -> K-mu(+)nu(mu) decay is reported. Using a data sample recorded in pp collisions in 2012 with the LHCb detector, corresponding to an integrated luminosity of 2 fb(-1), the branching fraction B(B-s(0) -> K-mu(+)nu(mu)) is measured to be [1.06 +/- 0.05(stat) +/- 0.08(syst)] x 10(-4), where the first uncertainty is statistical and the second one represents the combined systematic uncertainties. The decay B-s(0) -> D-s(-)mu(+)nu(mu), where D-s(-) is reconstructed in the final state K+K-pi(-), is used as a normalization channel to minimize the experimental systematic uncertainty. Theoretical calculations on the form factors of the B-s(0) -> K- and B-s(0) -> D-s(-) transitions are employed to determine the ratio of the Cabibbo-Kobayashi-Maskawa matrix elements vertical bar V-ub vertical bar/vertical bar V-cb vertical bar at low and high B-s(0) -> K- momentum transfer.
|
