| The longitudinal polarisation transfer from muons to $\\Lambda$ and $\\bar \\Lambda$ hyperons, $D^{$\\Lambda \\bar \\Lambda _{LL}$, has been studied in
deep inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN.
The spin transfers to $\\Lambda$ and $\\bar \\Lambda$ produced in the current fragmentation region exhibit different behaviours as a function of x and xF . The measured x and xF dependences of $D^ \\Lambda _{LL}$, are compatible with zero, while $D^{\\bar \\Lambda _{LL}$, tends to increase with xF , reaching values of 0.4 - 0.5. The resulting average values
are $D^ \\Lambda _{LL}$, = 0.012 $\\pm$ 0:047 $\\pm$ 0:024 and $D^{\\bar \\Lambda _{LL}$, = 0:249 $\\pm$ 0:056$\\pm$ 0:049. These results are discussed in
the frame of recent model calculations.
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