Measurement of the CP-even fraction of D0 → π+ π- π+ π-

作者：Ablikim, M.; Achasov, M. N.; Adlarson, P.; Albrecht, M.; Aliberti, R.; Amoroso, A.; An, M. R.; An, Q.; Bai, X. H.; Bai, Y.; Bakina, O.; Ferroli, R. Baldini; Balossino, I.; Ban, Y.; Batozskaya, V.; Becker, D.; Begzsuren, K.; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bloms, J.; Bortone, A.; Boyko, I.; Begzsuren, K.; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bloms, J.; Bortone, A.; Boyko, I.; Briere, R. A.; Brueggemann, A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G. F.; Cao, N.

来源：Physical Review D, 2022, 106(9): 092004.

DOI：10.1103/PhysRevD.106.092004

• DIFFERENCE
• PHASE

A measurement of the CP-even fraction of the decay D-0 -> pi(+) pi(-) pi(+) pi(-) is performed with a quantum-correlated psi(3770) -> D (D) over bar data sample collected by the BESIII experiment, corresponding to an integrated luminosity of 2.93 fb(-1). Using a combination of CP eigenstates, D-0 -> pi(+) pi(-) pi(+) pi(-) and D -> K-S,L(0) pi(+) pi(-) as tagging modes, the CP-even fraction is measured to be F-+(4 pi) = 0.735 +/- 0.015 +/- 0.005, where the first uncertainty is statistical and the second is systematic. This is the most precise determination of this quantity to date. It provides valuable model-independent input for the measurement of the angle gamma of the Cabibbo-Kobayashi-Maskawa matrix with B +/- -> DK +/- decays, and for time-dependent studies of CP violation and mixing in the D-0-(D) over bar (0) system.