First measurement of beam-recoil observables C{sub x} and C{sub z} in hyperon photoproduction
- Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)
- Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States)
- Old Dominion University, Norfolk, Virginia 23529 (United States)
Spin transfer from circularly polarized real photons to recoiling hyperons has been measured for the reactions {gamma}-vector+p{yields}K{sup +}+{lambda}-vector and {gamma}-vector+p{yields}K{sup +}+{sigma}-vector{sup 0}. The data were obtained using the CEBAF Large Acceptance Spectrometer (CLAS) detector at the Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85<cos{theta}{sub K{sup +}}{sup c.m.}<+0.95. For the {lambda}, the polarization transfer coefficient along the photon momentum axis, C{sub z}, was found to be near unity for a wide range of energy and kaon production angles. The associated transverse polarization coefficient C{sub x} is smaller than C{sub z} by a roughly constant difference of unity. Most significantly, the total {lambda} polarization vector, including the induced polarization P, has magnitude consistent with unity at all measured energies and production angles when the beam is fully polarized. For the {sigma}{sup 0} this simple phenomenology does not hold. All existing hadrodynamic models are in poor agreement with these results.
- OSTI ID:
- 20995164
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 75, Issue 3; Other Information: DOI: 10.1103/PhysRevC.75.035205; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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