2016/11/22 by Stanley J. Brodsky, Brodsky, Stanley J.
Physics and Astronomy · #Black Holes and Theoretical Physics #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.1611.07194
openalex publication_date 2016/11/22 · openalex created_date 2022/09/12 · openalex updated_date 2026/07/28
A remarkable feature of QCD is that the mass scale which controls color\nconfinement and hadron mass scales does not appear explicitly in the QCD\nLagrangian. However, de Alfaro, Fubini, and Furlan have shown that a mass scale\ncan appear in the equations of motion without affecting the conformal\ninvariance of the action if one adds a term to the Hamiltonian proportional to\nthe dilatation operator or the special conformal operator. Applying the same\nprocedure to the light-front Hamiltonian leads to a unique confinement\npotential \κ4 \ζ2 for mesons, where \ζ is the LF radial\nvariable conjugate to the invariant mass. The same result, including spin\nterms, is obtained using light-front holography, the duality between the front\nform and AdS5, if one modifies the action by the dilaton e\κ2 z2\nin the fifth dimension z. Generalizing this procedure using superconformal\nalgebra, leads to a unified Regge spectroscopy of meson, baryon, and\ntetraquarks, including remarkable supersymmetric relations between the masses\nof mesons and baryons of the same parity. One also predicts observables such as\nhadron structure functions, transverse momentum distributions, and the\ndistribution amplitudes defined from the hadronic light-front wavefunctions.\nThe mass scale underlying confinement and hadron masses can be connected to the\nmass parameter in the QCD running coupling by matching the nonperturbative\ndynamics to the perturbative QCD regime. The result is an effective coupling\ndefined at all momenta and the determination of a momentum scale which sets the\ninterface between perturbative and nonperturbative hadron dynamics. I also\ndiscuss evidence that the antishadowing of nuclear structure functions is\nnon-universal, and why shadowing and antishadowing phenomena may be\nincompatible with sum rules for nuclear parton distribution functions.\n