Higher-twist analysis of moments of spin structure function

Available analyses on moments of the spin structure function g_1 use different methods and are barely consistent with each other. We present a higher twist analysis of Gamma_1^p using a method consistent with the studies of Gamma_1^n and Gamma_1^(p-n) already published. The twist-4 coefficient f_2 is extracted. One result is that the higher twist coefficients seem to alternate signs: the relatively larger twist-6 contribution is partly suppressed by the twist-4 and twist-8 contributions. The size of twist-6 can be due to the elastic contribution to the moments.