July 31, 2018 to August 6, 2018
Maynooth University
Europe/Dublin timezone

Color Confinement, Hadron Dynamics, and Hadron Spectroscopy from Light-Front Holography and Superconformal Algebra

Aug 3, 2018, 2:30 PM
Hall E (Arts Bldg.)

Hall E

Arts Bldg.

Talk A: Vacuum structure and confinement Vacuum structure and confinement


Prof. Stanley J. Brodsky (SLAC National Accelerator Laboratory, Stanfird University)


QCD is not supersymmetrical in the traditional sense -- the QCD Lagrangian is based on quark and gluonic fields, not squarks nor gluinos. However, its hadronic eigensolutions conform to a representation of superconformal algebra, reflecting the underlying conformal symmetry of chiral QCD and its Pauli matrix representation.   The  eigensolutions of superconformal algebra provide a unified Regge spectroscopy of meson, baryon, and tetraquarks of the same parity and twist  as equal-mass members of the same 4-plet representation with a universal Regge slope.  The pion $q \bar q$ eigenstate has zero mass for $m_q=0.$  The superconformal relations also can be extended to  heavy-light quark mesons and baryons.  The combined approach of light-front holography and superconformal algebra also provides insight into the origin of the QCD mass scale and color confinement.  A key observation is the remarkable dAFF principle which shows how a mass scale can appear in the Hamiltonian and the equations of motion while retaining the conformal symmetry of the action.  When one applies the dAFF procedure to chiral QCD, a mass scale $\kappa$ appears which determines universal Regge slopes, hadron masses in the absence of the Higgs coupling, and the mass parameter underlying the Gaussian functional form of the nonperturbative QCD running coupling:  $\alpha_s(Q^2) \propto \exp{-{Q^2/4 \kappa^2}}$,  in agreement with the effective charge  determined from measurements of the Bjorken sum rule. The mass scale $\kappa$ underlying hadron masses  can be connected to the parameter   $\Lambda_{\overline {MS}}$ in the QCD running coupling by matching its predicted nonperturbative form to the perturbative QCD regime. The result is an effective coupling $\alpha_s(Q^2)$  defined at all momenta.   One also obtains empirically viable predictions for spacelike and timelike hadronic form factors, structure functions, distribution amplitudes, and transverse momentum distributions.  I will also discuss properties of the QCD and electroweak light-front vacuum.

Primary author

Prof. Stanley J. Brodsky (SLAC National Accelerator Laboratory, Stanfird University)

Presentation materials