Jefferson Lab experiment E97-103 measured the spin structure function (x, Q2) from Q 2 = 0.57 to 1.34 GeV2 with a nearly constant x ≈ 0.2. Combining this data with a fit to the world data, the size of higher twist contributions to can be extracted using the Wandzura-Wilczek relation. These higher twist contributions result from quark-gluon correlations and are expected to increase as Q2 decreases. This experiment was performed in Hall A with a longitudinally polarized electron beam and a high density polarized 3He gas target. This measurement reduced the error bars on in this kinematic region by an order of magnitude and is the first definitive non-zero measurement of in the deep inelastic scattering regime. The experiment also found a greater than two standard deviation difference between the experimental value for and in the three lowest Q2 points. This is the first evidence of higher twist effects in the deep inelastic scattering regime. |