High precision determination of the Q2 evolution of the Bjorken sum

We present a significantly improved determination of the Bjorken sum for 0.6 <= Q(2) <= 4.8 GeV2 using precise new g(1)(p) and g(1)(d) data taken with the CLAS detector at Jefferson Lab. A higher-twist analysis of the Q(2) dependence of the Bjorken sum yields the twist-4 coefficient f(2)(p-n) -0.064 +/- 0.009 +/-(0.032)(0.036). This leads to the color polarizabilities chi(p-n)(E) -0.032 +/- 0.024 and chi(p-n)(B) 0.032 +/- 0.013. The strong force coupling is determined to be alpha((MS) over bar)(s) (M-Z(2)) 0.1123 +/- 0.0061, which has an uncertainty a factor of 1.5 smaller than earlier estimates using polarized deep inelastic scattering (DIS) data. This improvement makes the comparison between alpha(s) extracted from polarized DIS and other techniques a valuable test of QCD.