13 research outputs found

    Higher Twist Effects in Deep Inelastic Scattering on Nuclei

    Get PDF
    Particle production in deep inelastic scattering on nuclei is reduced due to absorption of the produced particles in the nucleus. The photon ejects a quark from a bound nucleon which propagates through the nucleus forming a prehadron before turning into a hadron. We calculate the higher twist effect in hadronization which dominates the z1z \to 1 region of fragmentation.Comment: Based on a talk given by H.J. Pirner at the Fifth International Conference on Perspectives in Hadronic Physics, Trieste, May 200

    Vacuum Expectation Value of a Wegner-Wilson Loop near the Light Cone

    Get PDF
    Vacuum expectation values for one Wegner-Wilson loop representing a moving quark-antiquark pair are calculated in four-dimensional Euclidean and Minkowski space-time. The calculation uses gluon field strength correlators with perturbative gluon exchange and non-perturbative correlations from the stochastic vacuum model. The expectation value of a Wegner-Wilson loop forming a hyperbolic angle in Minkowski space-time is connected by an analytical continuation to the expectation value of the Wegner-Wilson loop in Euclidean four-space. The obtained result shows how confinement enters into the light-cone Hamiltonian for valence quarks independently of the chosen model.Comment: 12 pages, 2 figures, sections 2 and 3 shortened, more details added in section

    Linking the Quark Meson Model with QCD at High Temperature

    Full text link
    We model the transition of a system of quarks and gluons at high energies to a system of quarks and mesons at low energies in a consistent renormalization group approach. Flow equations interpolate between the physics of the high-temperature degrees of freedom and the low-temperature dynamics at a scale of 1 GeV. We also discuss the dependence of the equation of state on baryon density and compare our results with recent lattice gauge simulations.Comment: 11 pages, 4 figures additional discussion of the second order phase transitio

    Critical Correlations of Wilson Lines in SU(3) and the High Energy γp\gamma^*p Cross Section

    Full text link
    We discuss deep inelastic scattering at high energies as a critical phenomenon in 2+1 space - time dimensions. In the limit of Bjorken x0x \to 0, QCDQCD SU(3) with quark fields becomes a critical theory with a diverging correlation length ξ(x)x12λ2\xi(x) \propto x^{-\frac{1}{2 \lambda_2}} where the exponent λ2=2.52\lambda_2=2.52 is obtained from the center group Z(3) of SU(3). We conjecture that the dipole wave function of the virtual photon for transverse sizes 1/Q<x<ξ1/Q<x_{\bot}<\xi obeys correlation scaling Ψ(x)(1+n)\Psi \propto (x_{\bot})^{-(1+n)} before exponentially decaying for distances larger than the correlation length. Using this behavior combined with different xx -independent dipole proton cross sections we calculate the proton structure function and compare with the experimental data. We take the good agreement with the measured proton structure function F2(x,Q2)_2(x,Q^2) as an indication that at high energies dimensional reduction to an effective three dimensional theory with a critical point occurs.Comment: 21 pages, 3 figure

    The Spectrum of the Dirac Operator in the Linear Sigma Model with Quarks

    Full text link
    We derive the spectrum of the Dirac operator for the linear sigma-model with quarks in the large N_c approximation using renormalization group flow equations. For small eigenvalues, the Banks-Casher relation and the vanishing linear term are recovered. We calculate the coefficient of the next to leading term and investigate the spectrum beyond the low energy regime.Comment: 15 pages, 6 figures, to appear in Phys. Rev.