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Regular version of the site

Article

Search for CP violation in 𝐷+(𝑠)→ℎ+𝜋0 and 𝐷+(𝑠)→ℎ+𝜂 decays

Aaij R., Arzymatov K., Belavin V., Boldyrev A., Borisyak M., Derkach D., Hushchyn M., Karpov M., Maevskiy A., Philippov A., Popov S., Ratnikov F., Ryzhikov A., Ustyuzhanin A., Zunica G.

Searches for CP violation in the two-body decays 𝐷+(𝑠)→ℎ+𝜋0D(s)+→h+π0 and 𝐷+(𝑠)→ℎ+𝜂D(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 fb1 or 6 fb1 of integrated luminosity. The π0 and η mesons are reconstructed using the e+eγ final state, which can proceed as three-body decays π→ e+eγ and η → e+eγ, or via the two-body decays π→ γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes 𝐷+(𝑠)→𝐾0Sℎ+D(s)+→KS0h+ to cancel the production and detection asymmetries. The CP asymmetries are measured to be

𝐶𝑃(𝐷+→𝜋+𝜋0)=(−1.3±0.9±0.6)%,𝐶𝑃(𝐷+→𝐾+𝜋0)=(−3.2±4.7±2.1)%,𝐶𝑃(𝐷+→𝜋+𝜂)=(−0.2±0.8±0.4)%,𝐶𝑃(𝐷+→𝐾+𝜂)=(−6±10±4)%,𝐶𝑃(𝐷+𝑠→𝐾+𝜋0)=(−0.8±3.9±1.2)%,𝐶𝑃(𝐷+𝑠→𝜋+𝜂)=(0.8±0.7±0.5)%,𝐶𝑃(𝐷+𝑠→𝐾+𝜂)=(0.9±3.7±1.1)%,ACP(D+→π+π0)=(−1.3±0.9±0.6)%,ACP(D+→K+π0)=(−3.2±4.7±2.1)%,ACP(D+→π+η)=(−0.2±0.8±0.4)%,ACP(D+→K+η)=(−6±10±4)%,ACP(Ds+→K+π0)=(−0.8±3.9±1.2)%,ACP(Ds+→π+η)=(0.8±0.7±0.5)%,ACP(Ds+→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 𝐶𝑃ACP in these decay modes to date.