  The statistics of the magnetic field line separation provide insight into how
a bundle of field lines spreads out and the dispersion of non-thermal particles
in a turbulent environment, which underlies various astrophysical phenomena.
Its diffusive character depends on the distance along the field line, the
initial separation, and the characteristics of the magnetic turbulence. This
work considers the separation of two magnetic field lines in general transverse
turbulence in terms of the magnetic power spectrum in three-dimensional
wavenumber space. We apply non-perturbative methods using Corrsin's hypothesis
and assume random ballistic decorrelation to calculate the ensemble average
field line separation for general transverse magnetic turbulence. For 2D+slab
power spectra, our analytic formulae and computer simulations give similar
results, especially at low slab fraction. Our analytical expression also
demonstrates several features of field line separation that are verified by
computer simulations.
