Polarization phenomena in quantum chromodynamics

Conference · Thu Dec 01 04:00:00 EST 1994

OSTI ID:90756

Brodsky, S J ^[1]

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1. Stanford Univ., CA (United States)

The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and nonperturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g{sub A} on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x{sub bj}; (b) consequences of the principle of hadron retention in high x{sub F} inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. The author also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A{sub NN} observed in large angle proton-proton scattering, the anomalously large {rho}{pi} branching ratio of the J/{psi}, and the rapidly changing polarization dependence of both J/{psi} and continuum lepton pair hadroproduction observed at large x{sub F}. The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (United States)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 90756
• Report Number(s): SLAC--444; CONF-930767--; ON: DE95008628
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
MAGNETIC MOMENTS
POLARIZATION-ASYMMETRY RATIO
PROTON-PROTON INTERACTIONS
PROTONS
QUANTUM CHROMODYNAMICS
SPIN
STRUCTURE FUNCTIONS
TESTING