Hadron structure at low Q{sup 2}

Journal Article · Tue Jul 15 04:00:00 EDT 2008 · Reviews of Modern Physics

DOI:https://doi.org/10.1103/REVMODPHYS.80.731· OSTI ID:22038459

Drechsel, Dieter; Walcher, Thomas ^[1]

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1. Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz, D-55099 Mainz (Germany)

This review deals with the structure of hadrons, strongly interacting many-body systems consisting of quarks and gluons. These systems have a size of about 1 fm, which shows up in scattering experiments at low momentum transfers Q in the GeV region. At this scale the running coupling constant of quantum chromodynamics (QCD), the established theory of the strong interactions, becomes divergent. It is therefore highly intriguing to explore this theory in the realm of its strong interaction regime. However, the quarks and gluons cannot be resolved at the GeV scale but have to be studied through their manifestations in the bound many-body systems, for instance, pions, nucleons, and their resonances. The review starts with an overview of QCD at low momentum transfer and a summary of the theoretical apparatus describing the interaction of hadrons with electrons and photons. Experimental results are presented for the most significant observables studied with the electromagnetic probe: form factors, polarizabilities, excitation spectra, and sum rules. These experimental findings are compared and interpreted with various theoretical approaches to QCD, such as phenomenological models with quarks and pions, dispersion relations as a means to connect observables from different experiments, and, directly based on the QCD Lagrangian, chiral perturbation theory and lattice gauge theory.

• OSTI ID: 22038459
• Journal Information: Reviews of Modern Physics, Journal Name: Reviews of Modern Physics Journal Issue: 3 Vol. 80; ISSN 0034-6861; ISSN RMPHAT
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CHIRAL SYMMETRY
CHIRALITY
COUPLING CONSTANTS
FORM FACTORS
GAUGE INVARIANCE
GEV RANGE
GLUONS
LAGRANGIAN FIELD THEORY
LATTICE FIELD THEORY
LEPTON-HADRON INTERACTIONS
MOMENTUM TRANSFER
PERTURBATION THEORY
PHOTON-HADRON INTERACTIONS
PIONS
POLARIZABILITY
QUANTUM CHROMODYNAMICS
QUARKS
RESONANCE
STRONG INTERACTIONS
SUM RULES