  A search for direct CP violation in D0 -> h- h+ (where h=K or pi) is
presented using data corresponding to an integrated luminosity of 1.0 fb^-1
collected in 2011 by LHCb in pp collisions at a centre-of-mass energy of 7 TeV.
The analysis uses D0 mesons produced in inclusive semileptonic b-hadron decays
to the D0 mu X final state, where the charge of the accompanying muon is used
to tag the flavour of the D0 meson. The difference in the CP-violating
asymmetries between the two decay channels is measured to be
  Delta A_CP = A_CP(K-K+) - A_CP(pi-pi+) = (0.49 +- 0.30 (stat) +- 0.14 (syst))
% .
  This result does not confirm the evidence for direct CP violation in the
charm sector reported in other analyses.
