Disc formation in turbulent massive cores: Circumventing the magnetic
  braking catastrophe
  We present collapse simulations of 100 M_{\sun}, turbulent cloud cores
threaded by a strong magnetic field. During the initial collapse phase
filaments are generated which fragment quickly and form several protostars.
Around these protostars Keplerian discs with typical sizes of up to 100 AU
build up in contrast to previous simulations neglecting turbulence. We examine
three mechanisms potentially responsible for lowering the magnetic braking
efficiency and therefore allowing for the formation of Keplerian discs.
Analysing the condensations in which the discs form, we show that the build-up
of Keplerian discs is neither caused by magnetic flux loss due to turbulent
reconnection nor by the misalignment of the magnetic field and the angular
momentum. It is rather a consequence of the turbulent surroundings of the disc
which exhibit no coherent rotation structure while strong local shear flows
carry large amounts of angular momentum. We suggest that the "magnetic braking
catastrophe", i.e. the formation of sub-Keplerian discs only, is an artefact of
the idealised non-turbulent initial conditions and that turbulence provides a
natural mechanism to circumvent this problem.
