Observation of Beam Spin Asymmetries in the Process ep →e′π+π-X with CLAS12

(CLAS Collaboration)

doi:10.1103/PhysRevLett.126.152501

Observation of Beam Spin Asymmetries in the Process ep →e′π+π-X with CLAS12

(CLAS Collaboration)

Research output: Contribution to journal › Article › peer-review

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 G1. 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.

Original language	English
Article number	152501
Number of pages	6
Journal	Physical Review Letters
Volume	126
Issue number	15
DOIs	https://doi.org/10.1103/PhysRevLett.126.152501
Publication status	Published - 12 Apr 2021

Bibliographical note

Funding Information:
We acknowledge the outstanding efforts of the staff of the Accelerator and the Physics Divisions at Jefferson Lab in making this experiment possible. This work was supported in part by the U.S. Department of Energy, the National Science Foundation (NSF), the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS), the French Commissariat pour l′Energie Atomique, the UK Science and Technology Facilities Council, the National Research Foundation (NRF) of Korea, the Helmholtz-Forschungsakademie Hessen für FAIR (HFHF) and the Ministry of Science and Higher Education of the Russian Federation. The Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy under Contract No. DE-AC05-06OR23177. T. H. thanks the Department of Energy for support under Grant No. DE-FG02-96ER41003. The work of C. D. and A. V. is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No. DE-SC0019230 and No. DE-AC05-06OR23177.

Publisher Copyright:
© 2021 authors. Published by the American Physical Society.

Keywords

hep-ex

Access to Document

10.1103/PhysRevLett.126.152501Licence: CC BY

Observation of Beam Spin Asymmetries in the Process ep → e0 π + π −X with CLAS12Final published version, 629 KBLicence: CC BY

Cite this

@article{62ccfa3feeb64a62ba213906bbecd698,

title = "Observation of Beam Spin Asymmetries in the Process ep →e′π+π-X with CLAS12",

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 G1. 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.",

keywords = "hep-ex",

author = "{(CLAS Collaboration)} and Hayward, {T. B.} and C. Dilks and A. Vossen and H. Avakian and S. Adhikari and G. Angelini and M. Arratia and H. Atac and {Ayerbe Gayoso}, C. and Baltzell, {N. A.} and L. Barion and M. Battaglieri and I. Bedlinskiy and F. Benmokhtar and A. Bianconi and Biselli, {A. S.} and M. Bond{\`i} and F. Boss{\`u} and S. Boiarinov and Briscoe, {W. J.} and Brooks, {W. K.} and D. Bulumulla and Burkert, {V. D.} and Carman, {D. S.} and Carvajal, {J. C.} and A. Celentano and P. Chatagnon and T. Chetry and G. Ciullo and Clary, {B. A.} and Cole, {P. L.} and M. Contalbrigo and G. Costantini and V. Crede and A. D'Angelo and N. Dashyan and {De Vita}, R. and M. Defurne and A. Deur and S. Diehl and S. Fegan and K. Hicks and S. Lee and A. Thornton and Watts, {D. P.} and K. Wei and X. Wei and Wood, {M. H.} and N. Zachariou and J. Zhang",

note = "Funding Information: We acknowledge the outstanding efforts of the staff of the Accelerator and the Physics Divisions at Jefferson Lab in making this experiment possible. This work was supported in part by the U.S. Department of Energy, the National Science Foundation (NSF), the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS), the French Commissariat pour l′Energie Atomique, the UK Science and Technology Facilities Council, the National Research Foundation (NRF) of Korea, the Helmholtz-Forschungsakademie Hessen f{\"u}r FAIR (HFHF) and the Ministry of Science and Higher Education of the Russian Federation. The Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy under Contract No. DE-AC05-06OR23177. T. H. thanks the Department of Energy for support under Grant No. DE-FG02-96ER41003. The work of C. D. and A. V. is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No. DE-SC0019230 and No. DE-AC05-06OR23177. Publisher Copyright: {\textcopyright} 2021 authors. Published by the American Physical Society.",

year = "2021",

month = apr,

day = "12",

doi = "10.1103/PhysRevLett.126.152501",

language = "English",

volume = "126",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "15",

}

TY - JOUR

T1 - Observation of Beam Spin Asymmetries in the Process ep →e′π+π-X with CLAS12

AU - (CLAS Collaboration)

AU - Hayward, T. B.

AU - Dilks, C.

AU - Vossen, A.

AU - Avakian, H.

AU - Adhikari, S.

AU - Angelini, G.

AU - Arratia, M.

AU - Atac, H.

AU - Ayerbe Gayoso, C.

AU - Baltzell, N. A.

AU - Barion, L.

AU - Battaglieri, M.

AU - Bedlinskiy, I.

AU - Benmokhtar, F.

AU - Bianconi, A.

AU - Biselli, A. S.

AU - Bondì, M.

AU - Bossù, F.

AU - Boiarinov, S.

AU - Briscoe, W. J.

AU - Brooks, W. K.

AU - Bulumulla, D.

AU - Burkert, V. D.

AU - Carman, D. S.

AU - Carvajal, J. C.

AU - Celentano, A.

AU - Chatagnon, P.

AU - Chetry, T.

AU - Ciullo, G.

AU - Clary, B. A.

AU - Cole, P. L.

AU - Contalbrigo, M.

AU - Costantini, G.

AU - Crede, V.

AU - D'Angelo, A.

AU - Dashyan, N.

AU - De Vita, R.

AU - Defurne, M.

AU - Deur, A.

AU - Diehl, S.

AU - Fegan, S.

AU - Hicks, K.

AU - Lee, S.

AU - Thornton, A.

AU - Watts, D. P.

AU - Wei, K.

AU - Wei, X.

AU - Wood, M. H.

AU - Zachariou, N.

AU - Zhang, J.

N1 - Funding Information: We acknowledge the outstanding efforts of the staff of the Accelerator and the Physics Divisions at Jefferson Lab in making this experiment possible. This work was supported in part by the U.S. Department of Energy, the National Science Foundation (NSF), the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS), the French Commissariat pour l′Energie Atomique, the UK Science and Technology Facilities Council, the National Research Foundation (NRF) of Korea, the Helmholtz-Forschungsakademie Hessen für FAIR (HFHF) and the Ministry of Science and Higher Education of the Russian Federation. The Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy under Contract No. DE-AC05-06OR23177. T. H. thanks the Department of Energy for support under Grant No. DE-FG02-96ER41003. The work of C. D. and A. V. is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No. DE-SC0019230 and No. DE-AC05-06OR23177. Publisher Copyright: © 2021 authors. Published by the American Physical Society.

PY - 2021/4/12

Y1 - 2021/4/12

N2 - 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 G1. 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.

AB - 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 G1. 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.

KW - hep-ex

UR - http://www.scopus.com/inward/record.url?scp=85104475823&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.126.152501

DO - 10.1103/PhysRevLett.126.152501

M3 - Article

C2 - 33929247

SN - 0031-9007

VL - 126

JO - Physical Review Letters

JF - Physical Review Letters

IS - 15

M1 - 152501

ER -

Observation of Beam Spin Asymmetries in the Process ep →e′π+π-X with CLAS12

Abstract

Bibliographical note

Keywords

Access to Document

Other files and links

Nuclear Physics Consolidated Grant 2021-2024

Cite this

Observation of Beam Spin Asymmetries in the Process ep →e′π+π-X with CLAS12

Abstract

Bibliographical note

Keywords

Access to Document

Other files and links

Projects

Nuclear Physics Consolidated Grant 2021-2024

Cite this