====== TTP98-17 The b quark low-scale running mass from   Upsilon sum rules ======
 
 
   <hidden TTP98-17  The b quark low-scale running mass from   Upsilon sum rules > The b quark low-scale running mass m_kin
 is determined from an analysis
 of the Upsilon sum rules in the next-to-next-to-leading order (NNLO).
 It is demonstrated that using this mass one can significantly
 improve  the convergence of  the perturbation series for the
 spectral density  moments. We obtain 
 m_kin( 1 GeV ) = 4.56 \pm 0.06 GeV.
 Using this result we derive the value of the MS-bar
 mass  m:  m( m ) = 4.20 \pm 0.1 GeV.
 Contrary to the low-scale running mass, the pole mass of the
 b quark cannot be  reliably determined from the sum rules.
 As a byproduct of our study we find the NNLO analytical expression 
 for the cross section e+e- --> Q\bar Q of the quark antiquark 
 pair production in the threshold region, as well as the energy levels 
 and the wave functions at the origin for the ^1S_3 
 bound states of Q\bar Q.
 </hidden>
|**Kirill Melnikov and Alexander Yelkhovsky**  | 
|** Phys. Rev. D59 114009 1999  **  |
| {{preprints:1998:ttp98-17.pdf|PDF}} {{preprints:1998:ttp98-17.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9805270|arXiv]]   |
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