Measurement of the polarized structure functionσLT'for pion electroproduction in the Roper-resonance region

K S Joo ,S Stepanyan,K Lukashin,M Nozar,S Barrow,M Guillo,B Carnahan,P Corvisiero,S Strauch,F Sabatié,S Simionatto,N Pivnyuk,R A Schumacher,J P Santoro,M Taiuti,W Kim,U Thoma,A I Ostrovidov,S L Careccia,P Dragovitsch,J M Laget,C Butuceanu,A S Biselli,P V Degtyarenko,V S Serov,E De Sanctis,W J Briscoe,R W Gothe,H G Juengst,F W Hersman,G Asryan,I Niculescu,J Napolitano,M Osipenko,M Khandaker,L Farhi,S A Morrow,M Holtrop,K S Egiyan,M Bellis,K L Giovanetti,T A Forest,R Devita,A V Vlassov,V Batourine,S Pozdniakov,R A Niyazov,J Langheinrich,G Rosner,D Heddle,B E Bonner,R J Feuerbach,D Rowntree,J R Calarco,D S Carman,M Klusman,I I Strakovsky,S Boiarinov,G Niculescu,M Garçon,E Pasyuk,J Hardie,M Battaglieri,B Mckinnon,B L Berman,V Sapunenko,Y Prok,P Stoler,E Wolin,S Bueltmann,C Tur,K V Dharmawardane,N A Baltzell,D Protopopescu,K A Griffioen,A Shafi,C Cetina,M Anghinolfi,K Hicks,A Yegneswaran,R Bradford,J Lachniet,S Niccolai,E Anciant,D G Ireland,D Cords,S J Gaff,D Branford,I Bedlinskiy,M Ripani,D J Tedeschi,N Benmouna,G Ricco,R Fatemi,G Gavalian,E Polli,P Coltharp,V Gyurjyan,M Mirazita,H Egiyan,M Guidal,O P Dzyubak,C Djalali,K Mikhailov,P Eugenio,K Sabourov,A Deur,M Kossov,A Tkabladze,N Baillie,G Audit,H Avakian,Y Ilieva,S A Philips,M D Mestayer,S Mcaleer,Y G Sharabian,J H Kelley,G S Mutchler,O Pogorelko,D I Sober,K Beard,A V Skabelin,L C Maximon,K Livingston,H Bagdasaryan,B B Niczyporuk,D P Weygand,P L Cole,N Guler,B M Preedom,J J Manak,J D Kellie,G E Dodge,M Ungaro,I Hleiqawi,F X Girod,D Doughty,M Bektasoglu,P Ambrozewicz,H S Jo,S E Kuhn,J T Goetz,B Asavapibhop,J P Cummings,M Spraker,M M Ito,Volker Burkert ,G Fedotov,C A Meyer,B A Raue,J Shaw,D Lawrence,P D Rubin,T Auger,Alan Coleman ,J W Price,J Zhang,V Kubarovsky,Б С Ишханов ,H.r Weller ,T Lee,J Muêller ,A Klein,S O Nelson,A V Klimenko,M Williams,S Dytman,M Dugger,C E Hyde‐Wright ,N Bianchi,V Mokeev,Barry Ritchie ,V V Frolov ,A Empl,G Riccardi,L Elouadrhiri,P Rossi,K Wang,R Nasseripour,M F Vineyard,V Muccifora,G V O’rielly ,J Donnelly,W K Brooks,B E Stokes,I.g Aznauryan ,D Počanić ,S Chen,K Y Kim,H O Funsten ,E S Smith,A Stavinsky,R Minehart,Jaeseok Yun ,L Guo,J Kühn ,K Park,Pascal Girard ,J Pierce,D Jenkins,S Taylor,K Kim,L H Kramer,J F Hu ,L M Qin,K S Dhuga,R Miskimen,D Crabb,G A Peterson ,Claude Marchand ,R Thompson,G Feldman,Larry Weinstein ,F J Klein,G P Gilfoyle,L C Smith,S Bouchigny,M H Wood,G S Adams ,R Hakobyan ,F Ronchetti,L Dennis,C Salgado,P Nadel-Turoński ,L Zana,B A Mecking,J W C Mcnabb,J Ball

doi:10.1103/physrevc.72.058202

Abstract

The polarized longitudinal-transverse structure function $\sigma_{LT^\prime}$ measures the interference between real and imaginary amplitudes in pion electroproduction and can be used to probe the coupling between resonant and non-resonant processes. We report new measurements of $\sigma_{LT^\prime}$ in the $N(1440){1/2}^+$ (Roper) resonance region at $Q^2=0.40$ and 0.65 GeV$^2$ for both the $\pi^0 p$ and $\pi^+ n$ 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 $\sigma_{LT^\prime}(\pi^+ n)$ channel shows a large sensitivity to the Roper resonance multipoles $M_{1-}$ and $S_{1-}$ and provides new constraints on models of resonance formation.

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