Measurement of pi⁺pi^- Photoproduction in Double Polarization Experiments using the CLAS Spectrometer

Conference · Mon Oct 01 00:00:00 EDT 2007 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2813794· OSTI ID:921060

Hanretty, Charles ^[1]

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1. Florida State Univ., Tallahassee, FL (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 gammaN as well as to Neta, Neta[prime] or Deltapi(Delta-->ppi) 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⁺pi^- 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.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 921060
• Report Number(s): JLAB-PHY-07-756; DOE/OR/23177-0244; TRN: US0801917
• Journal Information: AIP Conference Proceedings, Vol. 947; Conference: VII Latin American Symposium on Nuclear Physics and Applications, Cusco, Peru, June 11-16, 2007; ISSN 0094-243X
• Publisher: AIP
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
AMPLITUDES
BARYONS
BUTANOLS
COUPLING CONSTANTS
DECAY
DEGREES OF FREEDOM
NUCLEAR PHYSICS
PARTIAL WAVES
PHOTON BEAMS
PHOTOPRODUCTION
POLARIZATION
QUANTUM CHROMODYNAMICS
QUARK MODEL
QUARKS
SPECTROMETERS
TARGETS