Résumé du preprint Irfu-08-26

Irfu-08-26
Polarized Structure Function $\sigma_{LT'}$ for $p({\vec e},e'K^+)\Lambda$ in the Nucleon Resonance Region
R. Nasseripour et al (R. de Masi, M. Garçon, F.X. Girod, J.M. Laget, S. Morrow, S. Procureur, F. Sabatié)
The first measurements of the polarized structure function $\\sigma_{LT\'}$ for the reaction $p(\\vec e,e\'K^+)\\Lambda$ in the nucleon resonance region are reported. Measurements are included from threshold up to $W$=2.05 GeV for central values of $Q^2$ of 0.65 and 1.00 GeV$^2$, and nearly the entire kaon center-of-mass angular range. $\\sigma_{LT\'}$ is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate s-channel resonances, as well as resonant and non-resonant processes. The results for $\\sigma_{LT\'}$ are comparable in magnitude to previously reported results from CLAS for $\\sigma_{LT}$, the real part of the same response. An intriguing sign change in $\\sigma_{LT\'}$ is observed in the high $Q^2$ data at $W\\approx 1.9$ GeV. Comparisons to several existing model predictions are shown.