2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/49160We begin with short review of the analytic approach (AA) to QCD recently developed and applied to the process of $e^+e^-$ annihilation into hadrons at low energies. Besides summary of the theoretical description of smeared experimental data for the $R$ cross-section ratio we give fresh analogous result for the corresponding Adler function, $D(Q^2)$, and demonstrate excellent agreement between the AA theoretical results and data in the low $Q^2$ region.7 pages, LaTeX with epsfig.sty, 3 PostScript figures Presented at the International Workshop "E+E- Collisions from phi to j/psi" Budker Institute of Nuclear Physics, Novosibirsk, Russia, March 1 - 5, 1999 (to appear in the Proceedings)High Energy Physics - Phenomenologytext