[48] S. J. Brodsky and H. J. Lu, “On the selfconsistency of scale setting methods,” arXiv:hep-ph/9211308 . [49] S. J. Brodsky, G. P. Lepage and P. B. Mackenzie, “On the Elimination of Scale Ambiguities in Perturbative Quantum Chromodynamics,” Phys. Rev. D 28 , 228 (1983). [50] P. A. Baikov, K. G. Chetyrkin and J. H. Kuhn, “Adler Function, Bjorken Sum Rule, and the Crewther Relation to Order α 4 s in a General Gauge Theory,” Phys. Rev. Lett. 104 , 132004 (2010) [ arXiv:1001.3606 [hep-ph]]. [51] E. Eichten, K. Gottfried, T. Kinoshita, K. D. Lane and T. M. Yan, “Charmonium: The Model,” Phys. Rev. D 17 , 3090 (1978); “Charmonium: Comparison With Experiment,” Phys. Rev. D 21 , 203 (1980). [52] A. Deur et al. , “Experimental determination of the evolution of the Bjorken integral at low Q $^{2}$,” Phys. Rev. Lett. 93 , 212001 (2004) [ arXiv:hep-ex/0407007 ]; A. Deur et al. , “Experi- mental study of isovector spin sum rules,” Phys. Rev. D 78 , 032001 (2008) [ arXiv:0802.3198 [nucl-ex]]. [53] J. H. Kim et al. , “A measurement of α$_{s}$ ( Q $^{2}$) from the Gross-Llewellyn Smith sum rule,” Phys. Rev. Lett. 81 , 3595 (1998) [ arXiv:hep-ex/9808015 ]. [54] S. Godfrey and N. Isgur, “Mesons in a Relativized Quark Model With Chromodynamics,” Phys. Rev. D 32 , 189 (1985). [55] The value of Λ$_{MS}$ is chosen so that α$_{MS}$ ( Q =1 GeV) = 0 . 45 ± 0 . 05, consistent with the value extracted from PDG. [56] The propagated Λ$_{MS}$ uncertainty is added in quadrature with the uncertainties due to the truncations of the β function and of the pQCD Bjorken sum rule series. The uncertainty due to the truncation of the β function is taken as the difference in α$_{MS}$ computed to second and first order in β . Similarly, the uncertainty due to the truncation of the pQCD expression of the Bjorken sum rule is taken as the difference between its estimates up to α 2 MS and α 3 $_{MS}$. [56] C. Amsler et al. [Particle Data Group], “Review of Particle Physics,” Phys. Lett. B 667 , 1 (2008). [57] The CSR concept shows that perturbation theory in the MS scheme is poorly convergent at small values of Q $^{2}$. For example, the first-order CSR scale shift from the MS scheme to the V scheme is Q ∗ 2 = 0 . 189 Q $^{2}$, [10] thus reducing significantly the range of applicability of pQCD. In contrast, the first-order scale shift from the g$_{1}$ scheme to the V scheme is Q ∗ 2 = 1 . 39 Q $^{2}$, 30