Measurement of the time-integrated CP asymmetry in D0 → K S 0 K S 0 decays

Abstract

A measurement of the time-integrated CP asymmetry in D0 → K S 0 K S 0 decays is reported. The data correspond to an integrated luminosity of about 2 fb−1 collected in 2015-2016 by the LHCb collaboration in pp collisions at a centre-of-mass energy of 13 TeV. The D0 candidate is required to originate from a D*+ → D0π+ decay, allowing the determination of the flavour of the D0 meson using the pion charge. The D0 → K+K− decay, which has a well measured CPasymmetry, is used as a calibration channel. The CP asymmetryfor D0 → K S 0 K S 0 is measured to beACP(D0→K0SK0S)=(4.3±3.4±1.0)%,ACP(D0→KS0KS0)=(4.3±3.4±1.0)%, where the first uncertainty is statistical and the second is systematic. This result is combined with the previous LHCb measurement at lower centre-of-mass energies to obtainACP(D0→K0SK0S)=(2.3±2.8±0.9)%.