185 research outputs found

    Boundary between Hadron and Quark/Gluon Structure of Nuclei

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    We show that the boundary between quark-dominated and hadron-dominated regions of nuclear structure may be blurred by multi-nucleon quark clusters arising from color percolation. Recent experiments supporting partial percolation in cold nuclei and full percolation in hot/dense nuclear matter include: deep inelastic lepton-nucleus scattering, relativistic heavy-ion collisions and the binding energy in 5HeΛ^5 He_{\Lambda}.Comment: 10 pages, 4 figures; added references; improved figures; fixed a typo (wrong sign in Eqn 6); Fixed typos in Equation 2; updated reference

    Quarkonium as relativistic bound state on the light front

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    We study charmonium and bottomonium as relativistic bound states in a light-front quantized Hamiltonian formalism. The effective Hamiltonian is based on light-front holography. We use a recently proposed longitudinal confinement to complete the soft-wall holographic potential for the heavy flavors. The spin structure is generated from the one-gluon exchange interaction with a running coupling. The adoption of asymptotic freedom improves the spectroscopy compared with previous light-front results. Within this model, we compute the mass spectroscopy, decay constants and the r.m.s. radii. We also present a detailed study of the obtained light-front wave functions and use the wave functions to compute the light-cone distributions, specifically the distribution amplitudes and parton distribution functions. Overall, our model provides a reasonable description of the heavy quarkonia.Comment: 28 pages, 17 figures, 5 tables. Supplemental Materials are provided in the source file under "Other formats" (see also "Ancillary files"

    J/ψ\psi production and suppression in nuclear collisions

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    In terms of a new QCD factorization formula for J/ψ\psi production, we calculate the J/ψ\psi suppression in nuclear collisions by including the multiple scattering between the pre-J/ψ\psi partonic states and the nuclear medium. We find agreement with all data on J/ψ\psi suppression in hadron-nucleus and nucleus-nucleus collisions, except a couple of points (the ``second drop'') at the highest ETE_T bins of the new NA50 data.Comment: Latex, 4 pages, to appear in the proceedings of Quark Matter 200

    Ab Initio Hamiltonian Approach to Light-Front Quantum Field Theory

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    Hamiltonian, Path Integral and BRST Formulations of Large N Scalar QCD2QCD_{2} on the Light-Front and Spontaneous Symmetry Breaking

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    Recently Grinstein, Jora, and Polosa have studied a theory of large-NN scalar quantum chromodynamics in one-space one-time dimension. This theory admits a Bethe-Salpeter equation describing the discrete spectrum of quark-antiquark bound states. They consider gauge fields in the adjoint representation of SU(N)SU(N) and scalar fields in the fundamental representation. The theory is asymptotically free and linearly confining. The theory could possibly provide a good field theoretic framework for the description of a large class of diquark-antidiquark (tetra-quark) states. Recently we have studied the light-front quantization of this theory without a Higgs potential. In the present work, we study the light-front Hamiltonian, path integral and BRST formulations of the theory in the presence of a Higgs potential. The light-front theory is seen to be gauge-invariant, possessing a set of first-class constraints. The explicit occurrence of spontaneous symmetry breaking in the theory is shown in unitary gauge as well as in the light-front 't Hooft gauge.Comment: Accepted for publication in Eur. Phys. J.