The polarized longitudinal-transverse structure function {sigma}{sub LT{sup '}} measures the interference between real and imaginary amplitudes in pion electroproduction and can be used to probe the ...coupling between resonant and nonresonant processes. We report new measurements of {sigma}{sub LT{sup '}} in the N(1440)(1/2){sup +} (Roper) resonance region at Q{sup 2}=0.40 and 0.65GeV{sup 2} for both the {pi}{sup 0}p and {pi}{sup +}n channels. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at a beam energy of 1.515 GeV. Complete angular distributions were obtained and are compared to recent phenomenological models. The {sigma}{sub LT{sup '}}({pi}{sup +}n) channel shows a large sensitivity to the Roper-resonance multipoles M{sub 1-} and S{sub 1-} and provides new constraints on models of resonance formation.
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The ep{yields}e{sup '}{pi}{sup +}n reaction was studied in the first and second nucleon resonance regions in the 0.25 GeV{sup 2}<Q{sup 2}<0.65 GeV{sup 2} range by use of the CLAS detector at Thomas ...Jefferson National Accelerator Facility. For the first time, to our knowledge, the absolute cross sections were measured, covering nearly the full angular range in the hadronic center-of-mass frame. We extracted the structure functions {sigma}{sub TL},{sigma}{sub TT}, and the linear combination {sigma}{sub T}+{epsilon}{sigma}{sub L} by fitting the {phi} dependence of the measured cross sections and compared them with the MAID and Sato-Lee models.
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The polarized longitudinal-transverse structure function {sigma}{sub LT{sup '}} has been measured using the p(e-vector,e{sup '}{pi}{sup +})n reaction in the {delta}(1232) resonance region at Q{sup ...2}=0.40 and 0.65 GeV{sup 2}. No previous {sigma}{sub LT{sup '}} data exist for this reaction channel. The kinematically complete experiment was performed at the Jefferson Lab with the CEBAF large acceptance spectrometer using longitudinally polarized electrons at an energy of 1.515 GeV. A partial-wave analysis of the data shows generally better agreement with recent phenomenological models of pion electroproduction compared to the previously measured {pi}{sup 0}p channel. A fit to both {pi}{sup 0}p and {pi}{sup +}n channels using a unitary isobar model suggests the unitarized Born terms provide a consistent description of the nonresonant background. The t-channel pion pole term is important in the {pi}{sup 0}p channel through a rescattering correction, which could be model dependent.
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