Measurement of {pi}{sup +}{pi}{sup -} Photoproduction in Double Polarization Experiments using the CLAS Spectrometer
- Florida State University, Tallahassee, FL 32306 (United States)
Spectroscopic predictions based on first principles are not possible in the non-perturbative regime of Quantum Chromodynamics (QCD) where the strong coupling constant is large. For this reason, effective theories and models have been developed to determine the masses, couplings, and decay widths of resonances. Various constituent quark models (CQMs) based on three quark degrees of freedom predict numerous baryon resonances that have not been experimentally verified and are thus 'missing'. The persistent non-observation of these states would present a big problem as the models would have failed to describe physical reality. CQMs predict strong couplings of these unobserved or missing states to {gamma}N as well as to N{eta}, N{eta}{sup '} or {delta}{pi}({delta}{yields}p{pi}) making photoproduction experiments a promising method to find these missing resonances. Previous analyses of unpolarized data show the importance of polarization obervables because some resonances reveal themselves more clearly in the interference with more dominant amplitudes. In addition, the determination of resonant contributions based on unpolarized data is not unique and requires further constraints provided by single- and double-polarization observables in the Partial Wave Analysis (PWA). A linearly- and circularly-polarized photon beam will be incident on a frozen-spin butanol target in Jefferson Lab's Hall B CLAS detector located in Newport News, Va. This detector allows the target to be polarized both longitudinally as well as transversely giving rise to measurable polarization observables in {pi}{sup +}{pi}{sup -} photoproduction. This experiment (FROST) will shed some light on the problem of the missing baryon resonances serving to better understand the properties of these states.
- OSTI ID:
- 21036020
- Journal Information:
- AIP Conference Proceedings, Vol. 947, Issue 1; Conference: 7. Latin American symposium on nuclear physics and applications, Cusco (Peru), 11-16 Jun 2007; Other Information: DOI: 10.1063/1.2813794; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMPLITUDES
BARYONS
CEBAF ACCELERATOR
MULTIPARTICLE SPECTROMETERS
PARTIAL WAVES
PARTICLE DECAY
PARTICLE WIDTHS
PHOTOPRODUCTION
PIONS MINUS
PIONS PLUS
POLARIZATION
QUANTUM CHROMODYNAMICS
QUARK MODEL
QUARKS
RESONANCE PARTICLES
REST MASS
STRONG-COUPLING MODEL