Electromagnetic meson form factor from a relativistic coupled-channels approach

Journal Article · Fri May 15 00:00:00 EDT 2009 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.79.055203· OSTI ID:21286977

Biernat, Elmar P; Schweiger, Wolfgang; Fuchsberger, Kajetan; Klink, William H ^[1]

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1. Institut fuer Physik, Universitaet Graz, A-8010 Graz (Austria)

Point-form relativistic quantum mechanics is used to derive an expression for the electromagnetic form factor of a pseudoscalar meson for spacelike momentum transfers. The elastic scattering of an electron by a confined quark-antiquark pair is treated as a relativistic two-channel problem for the qqe and qqe{gamma} states. With the approximation that the total velocity of the qqe system is conserved at (electromagnetic) interaction vertices this simplifies to an eigenvalue problem for a Bakamjian-Thomas type mass operator. After elimination of the qqe{gamma} channel the electromagnetic meson current and form factor can be directly read off from the one-photon-exchange optical potential. By choosing the invariant mass of the electron-meson system large enough, cluster separability violations become negligible. An equivalence with the usual front-form expression, resulting from a spectator current in the q{sup +}=0 reference frame, is established. The generalization of this multichannel approach to electroweak form factors for an arbitrary bound few-body system is quite obvious. By an appropriate extension of the Hilbert space this approach is also able to accommodate exchange-current effects.

• OSTI ID: 21286977
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 79, Issue 5; Other Information: DOI: 10.1103/PhysRevC.79.055203; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
APPROXIMATIONS
COUPLED CHANNEL THEORY
EIGENVALUES
ELASTIC SCATTERING
ELECTROMAGNETIC FORM FACTORS
ELECTROMAGNETIC INTERACTIONS
ELECTRONS
HILBERT SPACE
MASS
MOMENTUM TRANSFER
PHOTONS
PSEUDOSCALAR MESONS
QUANTUM MECHANICS
QUARK-ANTIQUARK INTERACTIONS
RELATIVISTIC RANGE
VELOCITY