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

13 November 2018

Abstract: A measurement of the time-integrated CP asymmetry in D 0  →  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 D 0 candidate is required to originate from a D *+ → D 0 π + decay, allowing the determination of the flavour of the D 0 meson using the pion charge. The D 0 → K + K − decay, which has a well measured CP asymmetry, is used as a calibration channel. The CP asymmetryfor D 0  →  K S 0 K S 0 is measured to be A C P D 0 → K S 0 K S 0 = 4.3 ± 3.4 ± 1.0 % , ${\mathcal{A}}^{CP}\left({D}^0\to {K}_S^0{K}_S^0\right)=\left(4.3\pm 3.4\pm 1.0\right)\%,$ 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 obtain A C P D 0 → K S 0 K S 0 = 2.3 ± 2.8 ± 0.9 % . ${\mathcal{A}}^{CP}\left({D}^0\to {K}_S^0{K}_S^0\right)=\left(2.3\pm 2.8\pm 0.9\right)\%.$

Published in: JHEP 1811 (2018) 048