Calculation of Quarkonium Spectrum and $m_b, m_c$ to Order $α_s^4$

Abstract

We include two loop, relativistic one loop and second order relativistic tree level corrections, plus leading nonperturbative contributions, to obtain a calculation of the lower states in the heavy quarkonium spectrum correct up to, and including, $O(α_s^4)$ and leading $Λ^4/m^4$ terms. This allows us, in particular, to obtain a model independent determination of the pole masses of the $b, c$ quarks, $$m_b=5 015^{+110}_{-70} mev; m_c=1 884^{+222}_{-133} mev$$ to which correspond the $\bar{\hbox{MS}}$ masses, $$\bar{m}_b(\bar{m}_b^2)=4 453^{+50}_{-32} mev; \bar{m}_c(\bar{m}_c^2)=1 547^{+169}_{-102} mev.$$ The decay $Γ(Υ\to e^+e^-)$ is found in agreement with experiment, $$Γ(Υ\to e^+e^-)=1.135^{+0.27}_{-0.29} kev (\hbox{exp.}=1.320\pm0.04 kev),$$ and the hyperfine splitting is predicted to be $$M(Υ)-M(η)=48.5^{+15.7}_{-12.2} mev.$$