Exclusive processes in perturbative quantum chromodynamics

Journal Article · Fri Oct 31 23:00:00 EST 1980 · Phys. Rev., D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.22.2157· OSTI ID:6804368

Lepage, G P; Brodsky, S J

We present a systematic analysis in perturbative quantum chromodynamics (QCD) of large-momentum-transfer exclusive processes. Predictions are given for the scaling behavior, angular dependence, helicity structure, and normalization of elastic and inelastic form factors and large-angle exclusive scattering amplitudes for hadrons and photons. We prove that these reactions are dominated by quark and gluon subprocesses at short distances, and thus that the dimensional-counting rules for the power-law falloff of these amplitudes with momentum transfer are rigorous predictions of QCD, modulo calculable logarithmic corrections from the behavior of the hadronic wave functions at short distances. These anomalous-dimension corrections are determined by evolution equations for process-independent meson and baryon ''distribution amplitudes'' phi(x/sub i/,Q) which control the valence-quark distributions in high-momentum-transfer exclusive reactions. The analysis can be carried out systematically in powers of ..cap alpha../sub s/(Q/sup 2/), the QCD running coupling constant. Although the calculations are most conveniently carried out using light-cone perturbation theory and the light-cone gauge, we also present a gauge-independent analysis and relate the distribution amplitude to a gauge-invariant Bethe-Salpeter amplitude.

• Research Organization: Laboratory of Nuclear Studies, Cornell University, Ithaca, New York 14853
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 6804368
• Journal Information: Phys. Rev., D; (United States), Journal Name: Phys. Rev., D; (United States) Vol. 22:9; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

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645400* -- High Energy Physics-- Field Theory
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
BETHE-SALPETER EQUATION
ELASTIC SCATTERING
ELEMENTARY PARTICLES
EQUATIONS
EXCLUSIVE INTERACTIONS
FIELD THEORIES
FORM FACTORS
GAUGE INVARIANCE
GLUONS
HADRONS
HELICITY
INELASTIC SCATTERING
INTERACTIONS
INVARIANCE PRINCIPLES
LIGHT CONE
MASSLESS PARTICLES
MOMENTUM TRANSFER
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PERTURBATION THEORY
PHOTONS
POSTULATED PARTICLES
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARKS
SCALING LAWS
SCATTERING
SCATTERING AMPLITUDES
SPACE-TIME