New constraints on dispersive form factor parametrizations from the timelike region

Journal Article · Tue Sep 01 04:00:00 EDT 1998 · Physical Review, D

DOI:https://doi.org/10.1103/PhysRevD.58.056001· OSTI ID:643593

Buck, W W ^[1]; Lebed, R F ^[2]

---

1. The Nuclear/High Energy Physics Research Center, Hampton University, Hampton, Virginia 23668 (United States)
2. The Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)

We generalize a recent model-independent form factor parametrization derived from rigorous dispersion relations to include constraints from data in the timelike region. These constraints dictate the convergence properties of the parametrization and appear as sum rules on the parameters. We further develop a new parametrization that takes into account finiteness and asymptotic conditions on the form factor, and use it to fit to the elastic {pi} electromagnetic form factor. We find that the existing world sample of timelike data gives only loose bounds on the form factor in the spacelike region, but we explain how the acquisition of additional timelike data and fits to other form factors are expected to give much better results. The same parametrization is seen to fit spacelike data extremely well. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 643593
• Journal Information: Physical Review, D, Journal Name: Physical Review, D Journal Issue: 5 Vol. 58; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CONVERGENCE
CROSSING SYMMETRY
DISPERSION RELATIONS
DUALITY
ELASTIC SCATTERING
ELECTROMAGNETIC FORM FACTORS
GREEN FUNCTION
LIMITING VALUES
PARTICLE PRODUCTION
PIONS
QUANTUM CHROMODYNAMICS
SUM RULES