Measurement of the time-integrated CP asymmetry in D⁰ → KS⁰KS⁰decays

Abstract: The time-integrated CP asymmetry in the decay D ⁰→ K _S ⁰K _S ⁰is measured using 3 fb ⁻¹of proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The flavour of the D ⁰meson is determined by use of the decay D ^*+→ D ⁰π ⁺and its charge conjugate mode. The result is A _CP=−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.