CLAS Physics Database

JLab | Search | Overview | Register | Login

E89-004

Spokesperson
R. A. Schumacher
Year
2005
Abstract
Spin transfer from circularly polarized real photons to recoiling hyperons has been measured for the reactions gamma + p -> K^+ + Lambda. The data were obtained using the CLAS detector at Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85 < cos(theta_K^+^{ c.m.}) < +0.95. For the Lambda, the polarization transfer coefficient along the photon momentum axis, C_z, was found to be near unity for a wide range of energy and kaon production angles. The associated transverse polarization coefficient, C_x, is smaller than C_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^0 this simple phenomenology does not hold. All existing hadrodynamic models are in poor agreement with these results.
Comment
Correlated data on W & cos(theta) distribution are available in E18M37 and E18M38 measurements.
Publication
  1. R. Bradford, R. A. Schumacher, and CLAS Collaboration First Measurement of Beam-Recoil Observables Cx and Cz in Hyperon Photoproduction // Submitted to Physical Review C
Quantities
Cx   Cz

Measurements

ID Quantity Beam Target Final state Q2min,
GeV2 		Q2max,
GeV2 		Wmin,
GeV 		Wmax,
GeV
E18M1 Cx γ p K+ Λ 0.0 0.0 1.679 1.679
E18M2 Cz γ p K+ Λ 0.0 0.0 1.679 1.679
E18M3 Cx γ p K+ Λ 0.0 0.0 1.734 1.734
E18M4 Cz γ p K+ Λ 0.0 0.0 1.734 1.734
E18M5 Cx γ p K+ Λ 0.0 0.0 1.787 1.787
E18M6 Cz γ p K+ Λ 0.0 0.0 1.787 1.787
E18M7 Cx γ p K+ Λ 0.0 0.0 1.839 1.839
E18M8 Cz γ p K+ Λ 0.0 0.0 1.839 1.839
E18M9 Cx γ p K+ Λ 0.0 0.0 1.889 1.889
E18M10 Cz γ p K+ Λ 0.0 0.0 1.889 1.889
E18M11 Cx γ p K+ Λ 0.0 0.0 1.939 1.939
E18M12 Cz γ p K+ Λ 0.0 0.0 1.939 1.939
E18M13 Cx γ p K+ Λ 0.0 0.0 1.987 1.987
E18M14 Cz γ p K+ Λ 0.0 0.0 1.987 1.987
E18M15 Cx γ p K+ Λ 0.0 0.0 2.035 2.035
E18M16 Cz γ p K+ Λ 0.0 0.0 2.035 2.035
E18M17 Cx γ p K+ Λ 0.0 0.0 2.081 2.081
E18M18 Cz γ p K+ Λ 0.0 0.0 2.081 2.081
E18M19 Cx γ p K+ Λ 0.0 0.0 2.126 2.126
E18M20 Cz γ p K+ Λ 0.0 0.0 2.126 2.126
E18M21 Cx γ p K+ Λ 0.0 0.0 2.17 2.17
E18M22 Cz γ p K+ Λ 0.0 0.0 2.17 2.17
E18M23 Cx γ p K+ Λ 0.0 0.0 2.212 2.212
E18M24 Cz γ p K+ Λ 0.0 0.0 2.212 2.212
E18M25 Cx γ p K+ Λ 0.0 0.0 2.255 2.255
E18M26 Cz γ p K+ Λ 0.0 0.0 2.255 2.255
E18M27 Cx γ p K+ Λ 0.0 0.0 2.296 2.296
E18M28 Cz γ p K+ Λ 0.0 0.0 2.296 2.296
E18M29 Cx γ p K+ Λ 0.0 0.0 2.338 2.338
E18M30 Cz γ p K+ Λ 0.0 0.0 2.338 2.338
E18M31 Cx γ p K+ Λ 0.0 0.0 2.377 2.377
E18M32 Cz γ p K+ Λ 0.0 0.0 2.377 2.377
E18M33 Cx γ p K+ Λ 0.0 0.0 2.416 2.416
E18M34 Cz γ p K+ Λ 0.0 0.0 2.416 2.416
E18M35 Cx γ p K+ Λ 0.0 0.0 2.454 2.454
E18M36 Cz γ p K+ Λ 0.0 0.0 2.454 2.454
E18M37 Cx γ p K+ Λ 0.0 0.0 1.679 2.454
E18M38 Cz γ p K+ Λ 0.0 0.0 1.679 2.454
Created in SINP MSU, CLAS Collaboration