Figure 1

$E(1{}^{3}P_1)-E(1{}^{3}P_0)$ versus the normalization scale $\mu$. The light band shows the LO expectation; the dark band shows the NLO expectation as from Eq. (26). The widths of the bands account for the uncertainty in ${\alpha }_s(M_Z)=0.1187\pm 0.002$ [22]. The horizontal band shows the experimental value $32.8\pm 1.2\mathrm{M}\mathrm{e}\mathrm{V}$ [22].Reuse & Permissions

Figure 2

$E(1{}^{3}P_2)-E(1{}^{3}P_1)$ versus the normalization scale $\mu$. The horizontal band shows the experimental value $19.9\pm 0.8\mathrm{M}\mathrm{e}\mathrm{V}$ [22]. All the rest is as in Fig. 1.Reuse & Permissions

Figure 3

$\rho$ versus the normalization scale $\mu$. The horizontal line at 0.8 corresponds to the LO expectation; the curve to the NLO expectation. The band accounts for the uncertainty in ${\alpha }_s(M_Z)=0.1187\pm 0.002$ [22]. The horizontal band at $0.607\pm 0.038$ shows the experimental value [22].Reuse & Permissions