Target and beam-target spin asymmetries in exclusive pion electroproduction for Q$^2$ > 1 GeV$^2$ . II. ep → e$\pi$$^0$p

P E Bosted (1) , Seungmin Kim , P P Adhikari , N D Adikaram , S A Akbar , N D Amaryan , P P Pereira , N A Avakian , M B Badui , J. Ball (2) , N B Balossino , N B Battaglieri , P E Bedlinskiy , B B Biselli , N B Boiarinov , D B Briscoe , M B Brooks , N B Bültmann , N B Burkert , H A Cao , N D Carman , N I Celentano , S A Chandavar , S A Crede , D D D 'Angelo , P P Dashyan , N I de Vita , N E de Sanctis , N D Deur , D D Djalali , P P Dupre , N E Egiyan , P E Alaoui , Nizar Fassi , N E Elouadrhiri , P E Eugenio , N E Fanchini , G G Fedotov , N K Hafidi , P P Hakobyan , N A Hanretty , N A Harrison , N I Hattawy , N D Heddle , H K Hicks , H G Hollis , N D Holtrop , E E Hughes , D K Ireland , P E Isupov , D B Jenkins , H A Jiang , P P Jo , S K Joo , D K Keller , P P Khachatryan , P P Khandaker , N K Kim , N K Klei , D K Klein , N K Koirala , N K Kubarovsky , N E Kuhn , N I Lanza , P P Lenisa , L K Livingston , L A Lu , D K Macgregor , N A Markov , N D Mayer , P E Mccracken , M B Mckinnon , M A Mineeva , N I Mirazita , N I Mokeev , M K Montgomery , N I Movsisyan , P P Camacho , M K Murdoch , P P Nadel-Turonski , N K Ni , P P Niccolai , N G Niculescu , N I Osipenko , S I Ostrovidov , P P Paolone , P P Paremuzyan , P P Park , P E Pasyuk , P P Phelps , P P Pisano , P E Pogorelko , P P Price , P P Prok , P P Protopopescu , P P Puckett , N B Raue , N I Ripani , N I Rizzo , G K Rosner , P P Rossi , Philippe Roy , F. Sabatié (2) , M A Saini , P P Schumacher , E E Seder , N G Sharabian , P P Skorodumina , D E Smith , D K Sokhan , P P Sparveris , E E Stankovic , N A Stepanyan , P P Stoler , D I Strakovsky , S A Strauch , N I Taiuti , Ye A Tian , N B Torayev , N A Ungaro , P P Voskanyan , P E Voutier , N K Walford , P E Watts , N A Wei , N B Weinstein , N E Zachariou

1 WM - College of William and Mary [Williamsburg]
2 DPHN - Département de Physique Nucléaire (ex SPhN)

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive pi(0) electroproduction reaction. gamma(*) p -> p pi(0), expanding an analysis of the. gamma(*) p -> n pi(+) reaction from the same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic ranges covered are 1.1 < W < 3 GeV and 1 < Q(2) < 6 GeV2. Results were obtained for about 5700 bins in W, Q(2), cos(theta(*)), and phi(*). The beam-target asymmetries were found to generally be greater than zero, with relatively modest phi(*) dependence. The target asymmetries exhibit very strong phi(*) dependence, with a change in sign occurring between results at low W and high W, in contrast to pi(+) electroproduction. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but significant differences are seen at higherW. When combined with cross-sectional measurements, as well as pi(+) observables, the present results will provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q(2), for resonances with masses as high as 2.4 GeV.

Domains: Nuclear Experiment [nucl-ex]

P E Bosted, Seungmin Kim, P P Adhikari, N D Adikaram, S A Akbar, et al.. Target and beam-target spin asymmetries in exclusive pion electroproduction for Q$^2$ > 1 GeV$^2$ . II. ep → e$\pi$$^0$p. Physical Review C, 2017, 95, pp.035207. ⟨10.1103/PhysRevC.95.035207⟩. ⟨cea-01535896⟩