Light‐Front Holography and Novel Effects in QCD

The correspondence between theories in anti‐de Sitter space and conformal field theories in physical space‐time leads to an analytic, semiclassical model for strongly‐coupled QCD. Light‐front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame‐independent light‐front wavefunctions of hadrons in physical space‐time, thus providing a relativistic description of hadrons at the amplitude level. We identify the AdS coordinate z with an invariant light‐front coordinate ζ which separates the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single‐variable light‐front Schrodinger equation for QCD which determines the eigenspectrum and the light‐front wavefunctions of hadrons for general spin and orbital angular momentum. The mapping of electromagnetic and gravitational form factors in AdS space to their corresponding expressions in light‐front theory confirms this correspondence. Some novel feature...