Evidence for large $α_s$ in the IR from the $Υ(1D)-χ_b(1P)$ and $χ_b(2P)-χ_b(1P)$ splittings

It is proved that the splittings $\Upsilon(1D)-\chi_b(1P)$ and $\chi_b(2P)-\chi_b(1P)$ can be in precise agreement with existing experimental data only if the coupling $\alpha_{\rm static}$ in the Cornell potential is large, $\alpha_{\rm static}=0.44\pm 0.02$. Alternatively, for a potential with the property of asymptotic freedom the extracted QCD constant $\Lambda$ (in the V-scheme) is $\Lambda(n_f=4)=395 \pm 10$ MeV which gives a large freezing value for the coupling, $\alpha_{\rm crit} \approx 0.60$, and at the same time corresponds to the conventional value $\Lambda_{\bar{\rm MS}} (n_f = 4) = 277 \pm 7$ MeV.