Polarizability in the Lyα_1/2 (1s_1/2 − 2p_1/2) and Lyα_3/2 (1s_1/2 − 2p_3/2) resonances (solid line). We note that denotes the mean energy of these transitions. Real and imaginary parts of the polarizability are detailed on the plot (dashed and dotted lines, respectively). The inner graph shows details of the Lyα_3/2 core. Evaluation of Lyman-α resonance without the effects of a fine structure and finite lifetime is represented by a dot-dashed line.