Light-front dynamics and AdS/QCD correspondence: The pion form factor in the space- and time-like regions

Journal Article · Sat Mar 01 00:00:00 EST 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.77.056007· OSTI ID:21249756

Brodsky, Stanley J ^[1]; Teramond, Guy F. de ^[1]

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1. Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (United States)

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently nonperturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of anti-de Sitter (AdS) space z and a specific light-front impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties and which allow the computation of decay constants, form factors and other exclusive scattering amplitudes. Relativistic light-front equations in ordinary space-time are found which reproduce the results obtained using the fifth-dimensional theory. As specific examples we compute the pion coupling constant f{sub {pi}}, the pion charge radius <r{sub {pi}}{sup 2}> and examine the propagation of the electromagnetic current in AdS space, which determines the space and timelike behavior of the pion form factor and the pole of the {rho} meson.

• OSTI ID: 21249756
• Journal Information: Physical Review. D, Particles Fields, Vol. 77, Issue 5; Other Information: DOI: 10.1103/PhysRevD.77.056007; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BARYONS
CONFORMAL INVARIANCE
COORDINATES
COUPLING CONSTANTS
DE SITTER GROUP
FORM FACTORS
MANY-DIMENSIONAL CALCULATIONS
PARTICLE DECAY
PIONS
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARKS
SCALE INVARIANCE
SCATTERING AMPLITUDES
SEMICLASSICAL APPROXIMATION
SPACE-TIME
STRING MODELS
STRONG-COUPLING MODEL
WAVE PROPAGATION