Quarkonium Spectroscopy and Perturbative QCD: A New Perspective
arXiv:hep-ph/0101305 · doi:10.1016/S0370-2693(01)00611-6
Abstract
We study the energy spectrum of bottomonium in perturbative QCD, taking alpha_s(Mz)=0.1181 +/- 0.0020 as input and fixing m_b^{MSbar}(m_b^{MSbar}) on the Upsilon(1S) mass. Contrary to wide beliefs, perturbative QCD reproduces reasonably well the gross structure of the spectrum as long as the coupling constant remains smaller than one. We perform a detailed analysis and discuss the size of non-perturbative effects. A new qualitative picture on the structure of the bottomonium spectrum is provided. The lowest-lying (c,cbar) and (b,cbar) states are also examined.
12 pages, 2 figures; Discussion on ultra-soft effects included; Some conservative error estimates added; Version to appear in Phys.Lett.B