101,954 research outputs found
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
Get PDFThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
B -> eta K-c(eta ' K-c) decays in QCD factorization
No full textWe study the exclusive decays of the B meson into pseudoscalar charmonium states eta(c) and eta(c)' within the QCD factorization approach and find that the non-factorizable corrections to naive factorization are infrared safe at leading-twist order. The spectator interactions arising from the kaon twist-3 effects are formally power suppressed but chirally and logarithmically enhanced. An important improvement by including the O(alpha(s)) corrections is the cancellation of the renormalization scale mu dependence of the decay amplitude. However, the calculated decay rates are too small to accommodate the experimental data. On the other hand, we compare the theoretical calculations for B meson decays to J/psi, psi', eta(c) and eta'(c), and find that the predicted relative decay rates of these four states are approximately compatible with the experimental data.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000223097800007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, Particles & FieldsSCI(E)17ARTICLE3365-3703
Molecular structure of highly excited resonant states in Mg-24 and the corresponding Be-8+O-16 and C-12+C-12 decays
No full textExotic Be-8 and C-12 decays from high-lying resonances in Mg-24 are analyzed in terms of a cluster model. The calculated quantities agree well with the corresponding experimental data. It is found that the calculated decay widths are very sensitive to the angular momentum carried by the outgoing cluster. It is shown that this property makes cluster decay a powerful tool to determine the spin as well as the molecular structures of the resonances.Physics, NuclearSCI(E)7ARTICLE5null8
Letter from J. E. Gavin to Louis C. Cramton regarding Sale of Bright Angel Trail
No full textLetter from J. E. Gavin to Louis C. Cramton regarding the Bright Angel Trail controversy, including newspaper clipping
Dieux guerriers, Chan à la galerie J. C. Riedel - 12, rue Guénégaud - 75006 Paris
No full textVideau André. Dieux guerriers, Chan à la galerie J. C. Riedel - 12, rue Guénégaud - 75006 Paris. In: Hommes et Migrations, n°1154, mai 1992. Le poids des mots. p. 63
Considering Future Consequences: An Integrative Model
No full textEdited by Lawrence J. Sanna and Edward C. Chan
Interpretation of Co-59 NMR shielding using the hard and soft acid-base concept - Insight into the relative magnitude of the nephelauxetic and the spectrochemical effect.
No full textMethods for C-C and C-N bond formation using earth-abundant metals
Get PDFThe formation of C–C and C–N bonds via transition metal catalysis is important in both academia and industry. Traditionally, both these fields have been dominated by the use of precious metal catalysts, with two of the most prominent reactions being the Suzuki– Miyaura cross-coupling (C–C) and the Buchwald–Hartwig amination (C–N), both palladium-catalysed processes. The use of earth-abundant metals in C–C and C–N formation could increase the economy and sustainability of such processes, whilst also introducing potential alternative reactivity.
The Suzuki–Miyaura cross-coupling is an extremely popular method of C–C bond formation in industry. The vast majority of investigation into this reaction concerns solely the palladium-catalysed process, however, the more abundant group 10 metal Ni has been shown to be proficient in this process, while also displaying access to an increased scope of electrophiles. Enclosed is a comparison of a nickel and palladium Suzuki–Miyaura cross-coupling using a comparable ligand system. The practicalities of changing to a nickel-catalysed system are discussed, as well as insights into mechanistic variances between the two systems.
The Chan-Lam amination is a copper promoted cross-coupling of amines and organoborons. Recently, there has been important disocoveries into the mechanism of the amination. The following study discusses the serendipitous discovery of a debenzylative Chan–Lam amination. This novel transformation was investigated, examining the scope of reactivity, whilst also considering the mechanistic pathway via which the reaction proceeds.
The use of boron protecting groups is well known in the Suzuki–Miyaura cross-coupling, but not as well explored in the Chan-Lam amination. The following study demonstrates the use of MIDA boronates in the Chan-Lam amination. The methodology attempts to access products not currently available using Chan-Lam aminations and also explores the difficulties of using the MIDA boronates in these systems
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
Get PDFFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
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