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- Title
Hadron Spectroscopy and Dynamics from Light-Front Holography and Superconformal Algebra.
- Authors
Brodsky, Stanley J.
- Abstract
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 qq¯<inline-graphic></inline-graphic> eigenstate has zero mass for mq=0.<inline-graphic></inline-graphic> 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 κ<inline-graphic></inline-graphic> 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: αs(Q2)∝exp-Q2/4κ2<inline-graphic></inline-graphic>, in agreement with the effective charge determined from measurements of the Bjorken sum rule. The mass scale κ<inline-graphic></inline-graphic> underlying hadron masses can be connected to the parameter ΛMS¯<inline-graphic></inline-graphic> in the QCD running coupling by matching its predicted nonperturbative form to the perturbative QCD regime. The result is an effective coupling αs(Q2)<inline-graphic></inline-graphic> 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.
- Subjects
HADRON spectroscopy; NUCLEAR spectroscopy; PARTICLE physics; HOLOGRAPHY; MOMENTUM distributions
- Publication
Few-Body Systems, 2018, Vol 59, Issue 5, p1
- ISSN
0177-7963
- Publication type
Article
- DOI
10.1007/s00601-018-1409-4