Improved measurement of the strong-phase difference δDKπ in quantum-correlated DD¯ decays

BESIII Collaboration

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The decay D→ K-π+ is studied in a sample of quantum-correlated DD¯ pairs, based on a data set corresponding to an integrated luminosity of 2.93 fb- 1 collected at the ψ(3770) resonance by the BESIII experiment. The asymmetry between CP-odd and CP-even eigenstate decays into K-π+ is determined to be AKπ= 0.132 ± 0.011 ± 0.007 , where the first uncertainty is statistical and the second is systematic. This measurement is an update of an earlier study exploiting additional tagging modes, including several decay modes involving a KL0 meson. The branching fractions of the KL0 modes are determined as input to the analysis in a manner that is independent of any strong phase uncertainty. Using the predominantly CP-even tag D→ π+π-π and the ensemble of CP-odd eigenstate tags, the observable AKππππ0 is measured to be 0.130 ± 0.012 ± 0.008. The two asymmetries are sensitive to rDKπcosδDKπ, where rDKπ and δDKπ are the ratio of amplitudes and phase difference, respectively, between the doubly Cabibbo-suppressed and Cabibbo-favoured decays. In addition, events containing D→ K-π+ tagged by D→KS,L0π+π- are studied in bins of phase space of the three-body decays. This analysis has sensitivity to both rDKπcosδDKπ and rDKπsinδDKπ. A fit to AKπ, AKππππ0 and the phase-space distribution of the D→KS,L0π+π- tags yields δDKπ=(187.6-9.7+8.9-6.4+5.4)∘, where external constraints are applied for rDKπ and other relevant parameters. This is the most precise measurement of δDKπ in quantum-correlated DD¯ decays.

Original languageEnglish
Article number1009
JournalEuropean Physical Journal C
Issue number11
Publication statusPublished - Nov 2022




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