404 research outputs found

    Charmed mesons in nuclear matter

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    We obtain the properties of charmed mesons in dense matter using a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner. We study the behaviour of dynamically-generated baryonic resonances together with the open-charm meson spectral functions in this dense nuclear environment. We discuss the implications of the in-medium properties of open-charm mesons on the Ds0(2317)D_{s0}(2317) and the predicted X(3700) scalar resonances, and on the formation of DD-mesic nuclei.Comment: 5 pages, 5 figures, 1 table, to appear in Proceedings of XIII International Conference on Hadron Spectroscopy, November 29 - December 4, 2009, Florida State Universit

    Systematic Study of Two-Pion Production in NN Collisions -- from Single-Baryon to Di-Baryon Excitations

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    The two-pion production in nucleon-nucleon collisions has been studied by exclusive and kinematically complete experiments from threshold up to TpT_p = 1.36 GeV at CELSIUS-WASA. At near-threshold energies the total and differential distributions for the π+π−\pi^+\pi^- and π0π0\pi^0\pi^0 channels are dominated by Roper excitation and its decay into NσN\sigma and Δπ\Delta\pi channels. At beam energies Tp>T_p > 1.1 GeV the ΔΔ\Delta\Delta excitation governs the two-pion production process. In the π+π+\pi^+\pi^+ channel evidence is found for the excitation of a higher-lying I=3/2 resonance, favorably the Δ(1600)\Delta(1600). The isovector fusion processes leading to the deuteron and to quasi-stable 2^2He, respectively, %with the production of an isovector pion-pair exhibit no or only a modest ABC-effect, {\it i.e.} low-mass enhancement in the ππ\pi\pi-invariant mass spectrum, and can be described by conventional tt-channel ΔΔ\Delta\Delta excitation. On the other hand, the isoscalar fusion process to the deuteron %with the production of an isoscalar pion-pair exhibits a dramatic ABC-effect correlated with a narrow resonance-like energy dependence in the total cross section with a width of only 50 MeV and situated at a mass 90 MeV below the ΔΔ\Delta\Delta mass.Comment: Proceedings HADRON0

    Cell-laden alginate hydrogels for the treatment of diabetes

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    Diabetes mellitus is an ever-increasing medical condition that currently suffers 1 of 11 adults who may have lifelong commitment with insulin injections. Cell-laden hydrogels releasing insulin may provide the ultimate means of correcting diabetes. Here, we provide insights of this cell-based approach including latest preclinical and clinical progress both from academia and industry

    Partial-wave analysis of the eta pi+ pi- system produced in the reaction pi-p --> eta pi+ pi- n at 18 GeV/c

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    A partial-wave analysis of 9082 eta pi+ pi- n events produced in the reaction pi- p --> eta pi+ pi- n at 18.3 GeV/c has been carried out using data from experiment 852 at Brookhaven National Laboratory. The data are dominated by J^{PC} = 0^{-+} partial waves consistent with observation of the eta(1295) and the eta(1440). The mass and width of the eta(1295) were determined to be 1282 +- 5 MeV and 66 +- 13 Mev respectively while the eta(1440) was observed with a mass of 1404 +- 6 MeV and width of 80 +- 21 MeV. Other partial waves of importance include the 1++ and the 1+- waves. Results of the partial wave analysis are combined with results of other experiments to estimate f1(1285) branching fractions. These values are considerably different from current values determined without the aid of amplitude analyses.Comment: 22 pages, 8 figure

    Observation of exotic meson production in the reaction π−p→η′π−p \pi^{-} p \to \eta^{\prime} \pi^- p at 18 GeV/c

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    An amplitude analysis of an exclusive sample of 5765 events from the reaction π−p→η′π−p\pi^{-} p \to \eta^{\prime} \pi^- p at 18 GeV/c is described. The η′π−\eta^{\prime} \pi^- production is dominated by natural parity exchange and by three partial waves: those with JPC=1−+,2++,J^{PC} = 1^{-+}, 2^{++}, and 4++4^{++}. A mass-dependent analysis of the partial-wave amplitudes indicates the production of the a2(1320)a_2(1320) meson as well as the a4(2040)a_4(2040) meson, observed for the first time decaying to η′π−\eta^{\prime}\pi^-. The dominant, exotic (non-qqˉ)q\bar{q}) 1−+1^{-+} partial wave is shown to be resonant with a mass of 1.597±0.010−0.010+0.0451.597 \pm 0.010^{+0.045}_{-0.010} GeV/c^2 and a width of 0.340±0.040±0.0500.340 \pm 0.040 \pm 0.050 GeV/c^2 . This exotic state, the π1(1600)\pi_1(1600), is produced with a tt dependence which is different from that of the a2(1320)a_2(1320) meson, indicating differences between the production mechanisms for the two states.Comment: 5 pages with 4 figure

    A partial wave analysis of the π0π0\pi ^0\pi ^0 system produced in π−p\pi ^-p charge exchange collisions

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    A partial wave analysis of the of the π0π0\pi ^0\pi ^0 system produced in the charge exchange reaction: π−p→π0π0n\pi ^-p\to \pi ^0\pi ^0n at an incident momentum of 18.3GeV/c18.3 GeV/c is presented as a function of π0π0{\pi ^0\pi ^0} invariant mass, mπ0π0m_{\pi^0\pi^0}, and momentum transfer squared, ∣t∣| {t} |, from the incident π−\pi^- to the outgoing π0π0{\pi ^0\pi ^0} system.Comment: 24 pages total,8 pages text, 14 figures, 1 table. Submitted to Phys Rev

    Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1GeV2 . I. ep→eπ+n

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    Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π + electroproduction reaction γ ∗ p → n π + . The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic range covered is 1.1 < W < 3 GeV and 1 < Q 2 < 6 GeV 2 . Results were obtained for about 6000 bins in W ,   Q 2 ,   cos ( θ ∗ ) , and ϕ ∗ . Except at forward angles, very large target-spin asymmetries are observed over the entire W region. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but very large differences are seen at higher values of W . A generalized parton distributions (GPD)-based model is in poor agreement with the data. When combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q 2 , for resonances with masses as high as 2.4 GeV
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