A Measurement of the Recoil Polarization of Electroproduced Λ(1116)
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States), S. McAleer · 2002
The CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Laboratory was used to study the reaction e + p → e' + K+ + Λ(1116) for events where Λ(1116) subsequently decayed via the channel Λ(1116) → p + π-. Data were taken at incident electron beam energies of 2.5, 4.0, and 4.2 GeV during the 1999 E1C run period. They hyperon production spectra span the Q2 range from 0.5 to 2.8 GeV2 and nearly the entire range in the center of mass angles. The proton angular distribution in the Λ(1116) rest frame is used to deduce the recoil polarization of the hyperon, and the W and cos θ$K+\atop{cm}$ dependence of the recoil polarization will be presented. The data show sizeable negative polarizations for the Λ(1116) as a function of both cos θ$K+\atop{cm}$ and W.