On Bjorken Sum Rule with Analytic Coupling at Low \({Q}^{{2}}\) Values

Below, we present a brief review of the recent studies of the polarized Bjorken sum rule \(\Gamma_{1}^{p-n}\left(Q^{2}\right)\) for small values of \(Q^{2}\). Our careful analysis reveals an excellent agreement between the experimental data and the predictions recently obtained in the framework of analytic QCD. Well-known perturbative expressions for coupling constant on the contrary lead to a strong difference between these data and turn out to be inapplicable. To estimate calculated phenomenological values, we discussed the photoproduction limit.