4,260 research outputs found

    Fine structure splittings of excited P and D states in charmonium

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    It is shown that the fine structure splittings of the 23PJ2 ^3P_J and 33PJ3 ^3P_J excited states in charmonium are as large as those of the 13PJ1^3P_J state if the same αs(μ)0.36\alpha_s(\mu)\approx 0.36 is used. The predicted mass M(23P0)=3.84M(2 ^3P_0)=3.84 GeV appears to be 120 MeV lower that the center of gravity of the 23PJ2 ^3P_J multiplet and lies below the DDˉD\bar D^* threshold. Our value of M(23P0)M(2 ^3P_0) is approximately 80 MeV lower than that from the paper by Godfrey and Isgur while the differences in the other masses are \la 20 MeV. Relativistic kinematics plays an important role in our analysis.Comment: 12 page

    A Crucial Test for Color-Octet Production Mechanism in Z^0 Decays

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    The direct production rates of DD-wave charmonia in the decays of Z0Z^0 is evaluated. The color-octet production processes Z03DJ(ccˉ)qqˉZ^0\rightarrow ^3D_J(c\bar c) q\bar q are shown to have distinctively large branching ratios, the same order of magnitude as that of J/ψJ/\psi prodution, as compared with other DD-wave charmonium production mechanisms. This may suggest a crucial channel to test the color-octet mechanism as well as to observe the DD-wave charmonium states in Z0Z^0 decays. In addition, a signal for the 3DJ^3D_J charmonium as strong as J/ψJ/\psi or ψ\psi^\prime with large transverse momentum at the Tevatron should also be observed.Comment: 14 pages in LaTex (3 figures in PS-file

    D-wave heavy quarkonium production in fixed target experiments

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    We calculate the DD-wave heavy quarkonium production at fixed target experiments under the NRQCD factorization formalism. We find that the color octet contributions are two orders of magnitude larger than color-singlet contributions if color-octet matrix elements are taken according to the NRQCD velocity scaling rules. Within the theoretical uncertainties, the prediction for the production rate of 22^{--} DD-wave charmonium state agrees with the preliminary result of E705 and other experiments. Searching for the 11^{--} DD-wave state ψ(3770)\psi(3770) is further suggested.Comment: 13pages, 4 PS figures, final vertion to appear in PR

    Production of pizero and eta mesons at large transverse momenta in pi-p and pi-Be interactions at 515 GeV/c

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    We present results on the production of high transverse momentum pizero and eta mesons in pi-p and pi-Be interactions at 515 GeV/c. The data span the kinematic ranges 1 < p_T < 11 GeV/c in transverse momentum and -0.75 < y < 0.75 in rapidity. The inclusive pizero cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k_T model.Comment: RevTeX4, 15 pages, 15 figures, to be submitted to Phys. Rev.

    Gluon fragmentation to ^3D_J quarkonia

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    We present a calculation of the leading order QCD fragmentation functions for gluons to split into spin-triplet D-wave quarkonia. We apply them to evaluate the gluon fragmentation contributions to inclusive ^3D_J quarkonium production at large transverse momentum processes like the Tevatron and find that the D-wave quarkonia, especially the charmonium 2^{--} state, could be observed through color-octet mechanism with present luminosity. Since there are distinctively large gaps between the contributions of two different (i.e, color-singlet and color-octet) quarkonium production mechanisms, our results may stand as a unique test to NRQCD color-octet quarkonium production mechanism.Comment: 15 pages in LaTex (2 figures in PS-file

    Search for Exotic Mesons in pi- P Interactions at 18 GeV/c

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    The recent search for non qqˉq \bar{q} mesons in πp\pi^{-}p interactions at Brookhaven National Laboratory is summarized. Many final states such as ηπ\eta \pi, ηπ\eta' \pi^{-}, a0πa_{0} \pi, f1πf_{1} \pi, a2πa_{2} \pi, b1πb_{1} \pi, which are favored decay modes of exotics, are under investigation.Comment: 9 pages, PostScript, Presented at the International School of Nuclear Physics, Erice, Sicily, Italy, September 199

    Anomalous J/psi suppression and charmonium dissociation cross sections

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    We study J/ψJ/\psi suppression in Pb+Pb collisions at CERN-SPS energies in hadronic matter with energy- and temperature-dependent charmonium dissociation cross sections calculated in the quark-interchange model of Barnes and Swanson. We find that the variation of J/ψ\psi survival probability from peripheral to central collisions can be explained as induced by hadronic matter absorption in central collisions.Comment: 30 pages, 8 figures, LaTex, changed for the latest NA50 dat

    Measurement of the J/Psi Production Cross Section in 920 GeV/c Fixed-Target Proton-Nucleus Interactions

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    The mid-rapidity (dsigma_(pN)/dy at y=0) and total sigma_(pN) production cross sections of J/Psi mesons are measured in proton-nucleus interactions. Data collected by the HERA-B experiment in interactions of 920 GeV/c protons with carbon, titanium and tungsten targets are used for this analysis. The J/Psi mesons are reconstructed by their decay into lepton pairs. The total production cross section obtained is sigma_(pN)(J/Psi) = 663 +- 74 +- 46 nb/nucleon. In addition, our result is compared with previous measurements

    Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System

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    The exclusive reaction πpηπ0n\pi^- p \to \eta \pi^0 n, ηπ+ππ0\eta \to \pi^+ \pi^- \pi^0 at 18 GeV/c/c has been studied with a partial wave analysis on a sample of 23~492 ηπ0n\eta \pi^0 n events from BNL experiment E852. A mass-dependent fit is consistent with a resonant hypothesis for the P+P_+ wave, thus providing evidence for a neutral exotic meson with JPC=1+J^{PC} = 1^{-+}, a mass of 1257±20±251257 \pm 20 \pm 25 MeV/c2/c^2, and a width of 354±64±60354 \pm 64 \pm 60 MeV/c2/c^2. New interpretations of the meson exotics in neutral ηπ0\eta \pi^0 system observed in E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase variations. p4, rewording paragrath "The second method ..." . p4, at the bottom of paragrath "The third method ..." added consistent with the results of methods 1 and 2
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