Beam-Helicity Asymmetries in Double-Charged-Pion Photoproduction on the Proton

Journal Article · Fri Oct 14 00:00:00 EDT 2005 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.95.162003· OSTI ID:20696562

Strauch, S ^[1]; Berman, B L; Benmouna, N; Bennhold, C; Briscoe, W J; Dhuga, K S; Feldman, G; Ilieva, Y; Lima, A C.S.; Nadel-Turonski, P; O'Rielly, G V; Philips, S A; Shafi, A; Strakovsky, I I ^[1]; Adams, G; Cummings, J P; Empl, A; Hu, J; Klusman, M; Kubarovsky, V ^[2]

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1. George Washington University, Washington, District of Columbia 20052 (United States)
2. Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States); and others

Beam-helicity asymmetries for the two-pion-photoproduction reaction {gamma}{yields}p{yields}p{pi}{sup +}{pi}{sup -} have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not provide an adequate description for the behavior of this new observable.

• OSTI ID: 20696562
• Journal Information: Physical Review Letters, Vol. 95, Issue 16; Other Information: DOI: 10.1103/PhysRevLett.95.162003; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR DISTRIBUTION
ASYMMETRY
CEBAF ACCELERATOR
CENTER-OF-MASS SYSTEM
CROSS SECTIONS
GAMMA RADIATION
GEV RANGE 01-10
HELICITY
HYDROGEN
PHOTON-PROTON INTERACTIONS
PHOTONS
PHOTOPRODUCTION
PIONS MINUS
PIONS PLUS
POLARIZATION
PROTON BEAMS
RESONANCE
SPECTROMETERS