Experimental study of the behavior of the Bjorken sum at very low Q2

A. Deur; J.P. Chen; S.E. Kuhn; C. Peng; M. Ripani; V. Sulkosky; K. Adhikari; M. Battaglieri; V.D. Burkert; G.D. Cates; R. De Vita; G.E. Dodge; L. El Fassi; F. Garibaldi; H. Kang; M. Osipenko; J.T. Singh; K. Slifer; J. Zhang; X. Zheng

Physics Letters B (Feb 2022)

Experimental study of the behavior of the Bjorken sum at very low Q2

A. Deur,
J.P. Chen,
S.E. Kuhn,
C. Peng,
M. Ripani,
V. Sulkosky,
K. Adhikari,
M. Battaglieri,
V.D. Burkert,
G.D. Cates,
R. De Vita,
G.E. Dodge,
L. El Fassi,
F. Garibaldi,
H. Kang,
M. Osipenko,
J.T. Singh,
K. Slifer,
J. Zhang,
X. Zheng

Affiliations

A. Deur: Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA; University of Virginia, Charlottesville, VA 22904, USA; Corresponding author.
J.P. Chen: Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
S.E. Kuhn: Old Dominion University, Norfolk, VA 23529, USA
C. Peng: Duke University, Durham, NC 27708, USA
M. Ripani: INFN, Sezione di Genova, 16146 Genova, Italy
V. Sulkosky: College of William and Mary, Williamsburg, VA 23187, USA; Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA; University of Virginia, Charlottesville, VA 22904, USA
K. Adhikari: Old Dominion University, Norfolk, VA 23529, USA; Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA; Mississippi State University, Mississippi State, MS 39762, USA
M. Battaglieri: Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA; INFN, Sezione di Genova, 16146 Genova, Italy
V.D. Burkert: Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
G.D. Cates: University of Virginia, Charlottesville, VA 22904, USA
R. De Vita: INFN, Sezione di Genova, 16146 Genova, Italy
G.E. Dodge: Old Dominion University, Norfolk, VA 23529, USA
L. El Fassi: Old Dominion University, Norfolk, VA 23529, USA; Mississippi State University, Mississippi State, MS 39762, USA
F. Garibaldi: INFN, Sezione di Roma, I-00185 Rome, Italy; Istituto Superiore di Sanità, I-00161 Rome, Italy
H. Kang: Seoul National University, Seoul, Republic of Korea
M. Osipenko: INFN, Sezione di Genova, 16146 Genova, Italy
J.T. Singh: University of Virginia, Charlottesville, VA 22904, USA
K. Slifer: University of Virginia, Charlottesville, VA 22904, USA; University of New Hampshire, Durham, NH 03824, USA
J. Zhang: University of Virginia, Charlottesville, VA 22904, USA
X. Zheng: University of Virginia, Charlottesville, VA 22904, USA

Journal volume & issue: Vol. 825
p. 136878

Abstract

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We present new data on the Bjorken sum Γ‾1p−n(Q2) at 4-momentum transfer 0.021≤Q2≤0.496 GeV2. The data were obtained in two experiments performed at Jefferson Lab: EG4 on polarized protons and deuterons, and E97110 on polarized 3He from which neutron data were extracted. The data cover the domain where chiral effective field theory (χEFT), the leading effective theory of the Strong Force at large distances, is expected to be applicable. We find that our data and the predictions from χEFT are only in marginal agreement. This is somewhat surprising as the contribution from the Δ(1232) resonance is suppressed in this observable, which should make it more reliably predicted by χEFT than quantities in which the Δ contribution is important. The data are also compared to a number of phenomenological models with various degrees of agreement.

Published in Physics Letters B

ISSN: 0370-2693 (Print); 1873-2445 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Physics
Website: http://www.journals.elsevier.com/physics-letters-b/

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