First Measurement of Hard Exclusive π^{-}Δ^{++} Electroproduction Beam-Spin Asymmetries off the Proton.

作者信息

Diehl S, Trotta N, Joo K, Achenbach P, Akbar Z, Armstrong W R, Atac H, Avakian H, Baashen L, Baltzell N A, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli A S, Bossù F, Brinkmann K-T, Briscoe W J, Bulumulla D, Burkert V, Capobianco R, Carman D S, Carvajal J C, Celentano A, Charles G, Chatagnon P, Chesnokov V, Ciullo G, Cole P L, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Deur A, Djalali C, Dupre R, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Gavalian G, Glazier D I, Golubenko A A, Gosta G, Gothe R W, Gotra Y, Griffioen K, Hafidi K, Hakobyan H, Hattawy M, Hayward T B, Heddle D, Hobart A, Holtrop M, Illari I, Ireland D G, Isupov E L, Jo H S, Johnston R, Keller D, Khachatryan M, Khanal A, Kim A, Kim W, Klimenko V, Kripko A, Kubarovsky V, Kuhn S E, Lagerquist V, Lanza L, Leali M, Lee S, Lenisa P, Li X, MacGregor I J D, Marchand D, Mascagna V, Matousek G, McKinnon B, McLauchlin C, Meziani Z E, Migliorati S, Milner R G, Mineeva T, Mirazita M, Mokeev V, Moran P, Munoz Camacho C, Naidoo P, Neupane K, Niccolai S, Niculescu G, Osipenko M, Pandey P, Paolone M, Pappalardo L L, Paremuzyan R, Paul S J, Phelps W, Pilleux N, Pokhrel M, Poudel J, Price J W, Prok Y, Radic A, Raue B A, Reed T, Richards J, Ripani M, Ritman J, Rossi P, Sabatié F, Salgado C, Schadmand S, Schmidt A, Sharabian Y G, Shrestha U, Sokhan D, Sparveris N, Spreafico M, Stepanyan S, Strakovsky I, Strauch S, Turisini M, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Voutier E, Watts D P, Wei X, Williams R, Wishart R, Wood M H, Yurov M, Zachariou N, Zhao Z W, Zurek M

机构信息

University of Connecticut, Storrs, Connecticut 06269, USA.

II Physikalisches Institut der Universitaet Giessen, 35392 Giessen, Germany.

出版信息

Phys Rev Lett. 2023 Jul 14;131(2):021901. doi: 10.1103/PhysRevLett.131.021901.

DOI:10.1103/PhysRevLett.131.021901

PMID:37505937

Abstract

The polarized cross-section ratio σ_{LT^{'}}/σ_{0} from hard exclusive π^{-}Δ^{++} electroproduction off an unpolarized hydrogen target has been extracted based on beam-spin asymmetry measurements using a 10.2 GeV/10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. The study, which provides the first observation of this channel in the deep-inelastic regime, focuses on very forward-pion kinematics in the valence regime, and photon virtualities ranging from 1.5 GeV^{2} up to 7 GeV^{2}. The reaction provides a novel access to the d-quark content of the nucleon and to p→Δ^{++} transition generalized parton distributions. A comparison to existing results for hard exclusive π^{+}n and π^{0}p electroproduction is provided, which shows a clear impact of the excitation mechanism, encoded in transition generalized parton distributions, on the asymmetry.

摘要