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Title: An Overview of Longitudinal Spin Structure Measurements from JLab

Jefferson Lab is currently one of the facilities leading the investigation of the spin structure of the nucleon. Over the past 15 years, several high precision measurements have been completed, extending our knowledge of the polarized structure functions g{sub 1} and g{sub 2} down to Q{sup 2} = 0.02 GeV{sup 2}. In particular, the low-Q{sup 2} range ({<=} 0.1 GeV{sup 2}) from these data allows us to make a benchmark-check of Chiral Perturbation theory ({chi}PT). Previous results for the moments of the spin structure functions in this region have shown mixed agreement. For {Gamma}{sub 1}, the first moment of g{sub 1}, we find good consistency between data and theory. However, we have seen a surprisingly large discrepancy with {chi}PT calculations for the {delta}{sub LT} spin polarizability on the neutron, which is significantly less sensitive to the {Delta}-resonance contribution. These proceedings will discuss the recent experimental effort at low Q{sup 2} from Jefferson Lab, including a discussion of preliminary results on the neutron. The new results on the neutron still show a sizeable discrepancy between data and theory. However, new calculations show improved agreement with data for some observables. In addition, new proton data for g{sub 2} is also expected tomore » help resolve the disagreement for {delta}{sub LT}.« less
  1. MIT, JLAB
Publication Date:
OSTI Identifier:
Report Number(s):
JLAB-PHY-12-1690; DOE/OR/23177-2752
DOE Contract Number:
Resource Type:
Resource Relation:
Journal Name: Proceedings of Science; Journal Volume: CD12; Conference: CD 12, August 6 -10, 2012, Newport News, Virginia, USA
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States