correcting MS-bar DR-bar conversion of mb and mtau

Dear Ben,

Peter and me think the MS-bar to DR-bar conversion of the fermion masses `mb` and `mtau` should involve `g'` (`= g1 * sqrt(0.6)`), and not `g1`.  Please see hep-ph/0311123 Eq. (19)

  http://arxiv.org/pdf/hep-ph/0311123v4

Best,
Alex