The time-integrated CP asymmetry in the decay D0 → K0
SK0
S
is measured
using 3 fb−1
of proton-proton collision data collected by the LHCb experiment at centreof-mass
energies of 7 and 8 TeV. The flavour of the D0 meson is determined by use of the
decay D∗+ → D0π
+ and its charge conjugate mode. The result is
ACP = −0.029 ± 0.052 ± 0.022 ,
where the first uncertainty is statistical and the second systematic. The result is consistent
with Standard Model expectations and improves the uncertainty with respect to the only
previous measurement of this quantity by more than a factor of three.