Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12

T B Hayward¹, C Dilks², A Vossen^{2

3}, H Avakian³, S Adhikari⁴, G Angelini⁵, M Arratia^{3

6}, H Atac⁷, C Ayerbe Gayoso¹, N A Baltzell³, L Barion⁸, M Battaglieri^{3

9}, I Bedlinskiy¹⁰, F Benmokhtar¹¹, A Bianconi^{12

13}, A S Biselli¹⁴, M Bondì⁹, F Bossù¹⁵, S Boiarinov³, W J Briscoe⁵, W K Brooks¹⁶, D Bulumulla¹⁷, V D Burkert³, D S Carman³, J C Carvajal⁴, A Celentano⁹, P Chatagnon¹⁸, T Chetry^{19

20}, G Ciullo^{8

21}, B A Clary²², P L Cole²³, M Contalbrigo⁸, G Costantini^{12

13}, V Crede²⁴, A D'Angelo^{25

26}, N Dashyan²⁷, R De Vita⁹, M Defurne¹⁵, A Deur³, S Diehl^{22

28}, C Djalali²⁰, R Dupre¹⁸, M Dugger²⁹, H Egiyan³, M Ehrhart^{18

30}, A El Alaoui¹⁶, L El Fassi¹⁹, L Elouadrhiri³, S Fegan³¹, A Filippi³², T A Forest³³, G Gavalian³, G P Gilfoyle³⁴, F X Girod³, D I Glazier³⁵, A A Golubenko³⁶, R W Gothe³⁷, Y Gotra³, K A Griffioen¹, M Guidal¹⁸, K Hafidi³⁰, H Hakobyan^{16

27}, M Hattawy¹⁷, F Hauenstein^{17

38}, K Hicks²⁰, A Hobart¹⁸, M Holtrop³⁹, D G Ireland³⁵, E L Isupov³⁶, H S Jo⁴⁰, K Joo²², S Joosten³⁰, D Keller⁴¹, M Khachatryan¹⁷, A Khanal⁴, A Kim²², W Kim⁴⁰, A Kripko²⁸, V Kubarovsky³, S E Kuhn¹⁷, L Lanza²⁵, M Leali^{12

13}, S Lee³⁸, P Lenisa^{8

21}, K Livingston³⁵, I J D MacGregor³⁵, D Marchand¹⁸, N Markov^{3

22}, L Marsicano⁹, V Mascagna^{13

42}, B McKinnon³⁵, Z E Meziani^{7

30}, M Mirazita⁴³, V Mokeev³, A Movsisyan⁸, C Munoz Camacho¹⁸, P Nadel-Turonski³, P Naidoo³⁵, S Nanda¹⁹, K Neupane³⁷, S Niccolai¹⁸, G Niculescu⁴⁴, T R O'Connell²², M Osipenko⁹, M Paolone^{7

45}, L L Pappalardo^{8

21}, R Paremuzyan^{3

39}, E Pasyuk³, W Phelps⁴⁶, O Pogorelko¹⁰, Y Prok¹⁷, B A Raue^{3

4}, M Ripani⁹, J Ritman⁴⁷, A Rizzo^{25

26}, P Rossi^{3

43}, J Rowley²⁰, F Sabatié¹⁵, C Salgado⁴⁸, A Schmidt⁵, E P Segarra³⁸, Y G Sharabian³, U Shrestha²⁰, D Sokhan³⁵, O Soto^{16

43}, N Sparveris⁷, S Stepanyan³, I I Strakovsky⁵, S Strauch³⁷, A Thornton³⁵, N Tyler³⁷, R Tyson³⁵, M Ungaro³, L Venturelli^{12

13}, H Voskanyan²⁷, E Voutier¹⁸, D P Watts³¹, K Wei²², X Wei³, M H Wood⁴⁹, B Yale¹, N Zachariou³¹, J Zhang⁴¹; CLAS Collaboration

Affiliations

¹ College of William and Mary, Williamsburg, Virginia 23187-8795, USA.
² Duke University, Durham, North Carolina 27708-0305, USA.
³ Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA.
⁴ Florida International University, Miami, Florida 33199, USA.
⁵ The George Washington University, Washington, D.C. 20052, USA.
⁶ University of California, Riverside, Riverside, California 92521, USA.
⁷ Temple University, Philadelphia, Pennsylvania 19122, USA.
⁸ INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
⁹ INFN, Sezione di Genova, 16146 Genova, Italy.
¹⁰ National Research Centre Kurchatov Institute-ITEP, Moscow 117259, Russia.
¹¹ Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, USA.
¹² Università degli Studi di Brescia, 25123 Brescia, Italy.
¹³ INFN, Sezione di Pavia, 27100 Pavia, Italy.
¹⁴ Fairfield University, Fairfield, Connecticut 06824, USA.
¹⁵ IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
¹⁶ Universidad Técnica Federico Santa María, Casilla 110-V Valparaíso, Chile.
¹⁷ Old Dominion University, Norfolk, Virginia 23529, USA.
¹⁸ Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France.
¹⁹ Mississippi State University, Mississippi State, Mississippi 39762-5167, USA.
²⁰ Ohio University, Athens, Ohio 45701, USA.
²¹ Università di Ferrara, 44121 Ferrara, Italy.
²² University of Connecticut, Storrs, Connecticut 06269, USA.
²³ Lamar University, 4400 MLK Boulevard, P.O. Box 10046, Beaumont, Texas 77710, USA.
²⁴ Florida State University, Tallahassee, Florida 32306, USA.
²⁵ INFN, Sezione di Roma Tor Vergata, 00133 Rome, Italy.
²⁶ Università di Roma Tor Vergata, 00133 Rome, Italy.
²⁷ Yerevan Physics Institute, 375036 Yerevan, Armenia.
²⁸ II. Physikalisches Institut der Universität Gießen, 35392 Gießen, Germany.
²⁹ Arizona State University, Tempe, Arizona 85287, USA.
³⁰ Argonne National Laboratory, Argonne, Illinois 60439, USA.
³¹ University of York, York YO10 5DD, United Kingdom.
³² INFN, Sezione di Torino, 10125 Torino, Italy.
³³ Idaho State University, Pocatello, Idaho 83209, USA.
³⁴ University of Richmond, Richmond, Virginia 23173, USA.
³⁵ University of Glasgow, Glasgow G12 8QQ, United Kingdom.
³⁶ Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119234 Moscow, Russia.
³⁷ University of South Carolina, Columbia, South Carolina 29208, USA.
³⁸ Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
³⁹ University of New Hampshire, Durham, New Hampshire 03824-3568, USA.
⁴⁰ Kyungpook National University, Daegu 41566, Republic of Korea.
⁴¹ University of Virginia, Charlottesville, Virginia 22901, USA.
⁴² Università degli Studi dell'Insubria, 22100 Como, Italy.
⁴³ INFN, Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
⁴⁴ James Madison University, Harrisonburg, Virginia 22807, USA.
⁴⁵ New Mexico State University, P.O. Box 30001, Las Cruces, New Mexico 88003, USA.
⁴⁶ Christopher Newport University, Newport News, Virginia 23606, USA.
⁴⁷ Institute fur Kernphysik (Juelich), Juelich 52428, Germany.
⁴⁸ Norfolk State University, Norfolk, Virginia 23504, USA.
⁴⁹ Canisius College, Buffalo, New York 14208-1098, USA.

PMID: 33929247
DOI: 10.1103/PhysRevLett.126.152501

Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12

T B Hayward et al. Phys Rev Lett. 2021.

. 2021 Apr 16;126(15):152501.

doi: 10.1103/PhysRevLett.126.152501.

Authors

Affiliations

¹ College of William and Mary, Williamsburg, Virginia 23187-8795, USA.
² Duke University, Durham, North Carolina 27708-0305, USA.
³ Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA.
⁴ Florida International University, Miami, Florida 33199, USA.
⁵ The George Washington University, Washington, D.C. 20052, USA.
⁶ University of California, Riverside, Riverside, California 92521, USA.
⁷ Temple University, Philadelphia, Pennsylvania 19122, USA.
⁸ INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
⁹ INFN, Sezione di Genova, 16146 Genova, Italy.
¹⁰ National Research Centre Kurchatov Institute-ITEP, Moscow 117259, Russia.
¹¹ Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, USA.
¹² Università degli Studi di Brescia, 25123 Brescia, Italy.
¹³ INFN, Sezione di Pavia, 27100 Pavia, Italy.
¹⁴ Fairfield University, Fairfield, Connecticut 06824, USA.
¹⁵ IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
¹⁶ Universidad Técnica Federico Santa María, Casilla 110-V Valparaíso, Chile.
¹⁷ Old Dominion University, Norfolk, Virginia 23529, USA.
¹⁸ Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France.
¹⁹ Mississippi State University, Mississippi State, Mississippi 39762-5167, USA.
²⁰ Ohio University, Athens, Ohio 45701, USA.
²¹ Università di Ferrara, 44121 Ferrara, Italy.
²² University of Connecticut, Storrs, Connecticut 06269, USA.
²³ Lamar University, 4400 MLK Boulevard, P.O. Box 10046, Beaumont, Texas 77710, USA.
²⁴ Florida State University, Tallahassee, Florida 32306, USA.
²⁵ INFN, Sezione di Roma Tor Vergata, 00133 Rome, Italy.
²⁶ Università di Roma Tor Vergata, 00133 Rome, Italy.
²⁷ Yerevan Physics Institute, 375036 Yerevan, Armenia.
²⁸ II. Physikalisches Institut der Universität Gießen, 35392 Gießen, Germany.
²⁹ Arizona State University, Tempe, Arizona 85287, USA.
³⁰ Argonne National Laboratory, Argonne, Illinois 60439, USA.
³¹ University of York, York YO10 5DD, United Kingdom.
³² INFN, Sezione di Torino, 10125 Torino, Italy.
³³ Idaho State University, Pocatello, Idaho 83209, USA.
³⁴ University of Richmond, Richmond, Virginia 23173, USA.
³⁵ University of Glasgow, Glasgow G12 8QQ, United Kingdom.
³⁶ Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119234 Moscow, Russia.
³⁷ University of South Carolina, Columbia, South Carolina 29208, USA.
³⁸ Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
³⁹ University of New Hampshire, Durham, New Hampshire 03824-3568, USA.
⁴⁰ Kyungpook National University, Daegu 41566, Republic of Korea.
⁴¹ University of Virginia, Charlottesville, Virginia 22901, USA.
⁴² Università degli Studi dell'Insubria, 22100 Como, Italy.
⁴³ INFN, Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
⁴⁴ James Madison University, Harrisonburg, Virginia 22807, USA.
⁴⁵ New Mexico State University, P.O. Box 30001, Las Cruces, New Mexico 88003, USA.
⁴⁶ Christopher Newport University, Newport News, Virginia 23606, USA.
⁴⁷ Institute fur Kernphysik (Juelich), Juelich 52428, Germany.
⁴⁸ Norfolk State University, Norfolk, Virginia 23504, USA.
⁴⁹ Canisius College, Buffalo, New York 14208-1098, USA.

PMID: 33929247
DOI: 10.1103/PhysRevLett.126.152501

Abstract

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function e(x), which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function G_{1}^{⊥}. A clear sign change is observed around the ρ mass that appears in model calculations and is indicative of the dependence of the produced pions on the helicity of the fragmenting quark.

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Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12

Affiliations

Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12

Authors

Affiliations

Abstract