Search for CP violation in D + (s) → h + π 0 and D + (s) → h + η decays

• Published in: The journal of high energy physics no. 6
• Main Authors: Aaij, R., Eklund, Lars, Zunica, G.
• Format: Journal Article
• Language: English
• Published: 2021
• Subjects: Charm physics; CP violation; Hadron-Hadron scattering (experiments)
• ISSN: 1126-6708; 1029-8479
• DOI: 10.1007/JHEP06(2021)019

Searches for CP violation in the two-body decays D + (s) → h + π 0 and D + (s) → h + η (where h + denotes a π + or K + meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb − 1 or 6 fb − 1 of integrated luminosity. The π 0 and η mesons are reconstructed using the e + e − γ final state, which can proceed as three-body decays π 0 → e + e − γ and η → e + e − γ , or via the two-body decays π 0 → γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes D + (s) → K 0 S h + to cancel the production and detection asymmetries. The CP asymmetries are measured to be A CP (D + → π+π 0 ) = (−1.3±0.9±0.6)%, A CP (D + → K + π 0 ) = (−3.2±4.7±2.1)%, A CP (D + → π + η) = (−0.2±0.8±0.4)%, A CP (D + → K + η) = (−6±10±4)%, A CP (D + s → K + π 0 ) = (−0.8±3.9±1.2)%, A CP (D + s → π + η) = (0.8±0.7±0.5)%, A CP (D + s →K + η) = (0.9±3.7±1.1)%, where the first uncertainties are statistical and the second systematic. These results are consistent with no CP violation and mostly constitute the most precise measurements of A CP in these decay modes to date.