Simultaneous decoupling of bottom and charm quarks
  Parameters and light fields of the QCD Lagrangian with two heavy flavours, b and c, are related to those in the low-energy effective theory without these flavours, to three-loop accuracy taking into account the exact dependence on m_c/m_b. Similar relations for bilinear quark currents are also considered. 
Andrey Grozin, Maik H\"oschele, Jens Hoff, Matthias Steinhauser
hep-ph