[Gdh_lowq2] Abstract for Baryons 2016 talk

[Krishna Adhikari]

Dear all, 
Please find below the draft of the abstract for my Baryons 2016 (http://baryons2016.physics.fsu.edu/) talk. Please let me know if you have comments or corrections. 



New results on spin structure functions at very low momentum transfers from Jefferson Lab Several experiments in Jefferson Lab have collected a large amount of data on the spin structure of nucleons using polarized electron beam directed on various polarized targets (NH 3 and ND 3 , 3 He). In these double polarization experiments, either the double spin asymmetries A || and A ⊥ or the polarized cross section differences Δσ || and Δσ ⊥ are measured with an unprecedented precision over a wide kinematic range, with 0.02 GeV 2 < Q 2 < 5.0 GeV 2 and 1.08 GeV < W < 3.0 GeV and from these measurements, the spin structure functions and their moments are extracted. These data help us shed more light on the nucleon spin structure in the region of quark-confinement as well in the transition region between hadronic and partonic degrees of freedom. With these data, it is possible to put constraints on quark-hadron duality, test pQCD predictions for the quark polarization at large x, and test various predictions for moments of structure functions from sum rules and QCD based effective theories such as Chiral Perturbation Theory (χPT) as well as from phenomenological models. Additionally, these data make it possible to perform more precise calculations of higher-twist matrix elements in the framework of the Operator Product Expansion. At very low momentum transfers (Q 2 →0), the first moment (Γ 1 ) of structure function g 1 is constrained by the GDH sum rule and its χ PT extensions, which makes measurements of g 1 in this region uniquely interesting. In this talk, I will present new results on spin structure functions from various experiments at Jefferson Lab with an emphasis on low Q 2 measurements. In particular, I will present new results from the EG4 experiment with CLAS, which measured the double polarized cross section difference on NH 3 and ND 3 (with both electron beam and targets longitudinally polarized) down to Q 2 = 0.02 GeV 2 . 

Thank you. 
With best regards, 
Krishna 

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