Measurement of single spin asymmetry and fifth structure function for the p($$\vec{e}$$, e' K+)Lambda reaction with CEBAF Large Acceptance Spectrometer (CLAS)
- Florida Intl Univ., Miami, FL (United States)
The single spin asymmetry, ALT', and the polarized structure function, σLT', for the p($$\vec{e}$$, e' K+) reaction in the resonance region have been measured and extracted using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Data were taken at an electron beam energy of 2.567 GeV. The large acceptance of CLAS allows for full azimuthal angle coverage over a large range of center-of-mass scattering angles. Results were obtained that span a range in Q2 from 0.5 to 1.3 GeV2 and W from threshold up to 2.1 GeV and were compared to existing theoretical calculations. The polarized structure function is sensitive to the interferences between various resonant amplitudes, as well as to resonant and non-resonant amplitudes. This measurement is essential for understanding the structure of nucleons and searching for previously undetected nucleon excited states (resonances) predicted by quark models. The W dependence of the σLT' in the kinematic regions dominated by s and u channel exchange (cos θ$$cm\atop{k}$$ = -0.50, -0.167, 0.167) indicated possible resonance structures not predicted by theoretical calculations. The σLT' behavior around W = 1.875 GeV could be the signature of a resonance predicted by the quark models and possibly seen in photoproduction. In the very forward angles where the reaction is dominated by the t-channel, the average σLT' was zero. There was no indication of the interference between resonances or resonant and non-resonant amplitudes. This might be indicating the dominance of a single t-channel exchange. Study of the sensitivity of the fifth structure function data to the resonance around 1900 MeV showed that these data were highly sensitive to the various assumptions of the models for the quantum number of this resonance. This project was part of a larger CLAS program to measure cross sections and polarization observables for kaon electroproduction in the nucleon resonance region.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 893284
- Report Number(s):
- JLAB-PHY-04-327; DOE/ER/40150-4072; AAT3165151; 0-542-00428-3; TRN: US0605973
- Country of Publication:
- United States
- Language:
- English
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