TY - JOUR

T1 - First Observation of Quantum Correlations in e+e-→XDD¯ and C-Even Constrained DD¯ Pairs

AU - BESIII Collaboration

AU - Ачасов, Михаил Николаевич

AU - Мучной, Николай Юрьевич

AU - Николаев, Иван Борисович

N1 - The BESIII Collaboration thanks the staff of BEPCII [38] and the IHEP computing center for their strong support. This work is supported in part by National Key R&D Program of China under Contracts No. 2023YFA1606000, No. 2023YFA1606704; National Natural Science Foundation of China (NSFC) under Contracts No. 11635010, No. 11935015, No. 11935016, No. 11935018, No. 12025502, No. 12035009, No. 12035013, No. 12061131003, No. 12192260, No. 12192261, No. 12192262, No. 12192263, No. 12192264, No. 12192265, No. 12221005, No. 12225509, No. 12235017, No. 12361141819; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; CAS under Contract No. YSBR-101; 100 Talents Program of CAS; The Institute of Nuclear and Particle Physics (INPAC) and Shanghai Key Laboratory for Particle Physics and Cosmology; Agencia Nacional de Investigación y Desarrollo de Chile (ANID), Chile under Contract No. ANID PIA/APOYO AFB230003; ERC under Contract No. 758462; German Research Foundation DFG under Contract No. FOR5327; Istituto Nazionale di Fisica Nucleare, Italy; Knut and Alice Wallenberg Foundation under Contracts No. 2021.0174, No. 2021.0299; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Research Foundation of Korea under Contract No. NRF-2022R1A2C1092335; National Science and Technology fund of Mongolia; Polish National Science Centre under Contract No. 2024/53/B/ST2/00975; STFC (United Kingdom); Swedish Research Council under Contract No. 2019.04595; U.S. Department of Energy under Contract No. DE-FG02-05ER41374.

PY - 2025/10/20

Y1 - 2025/10/20

N2 - The study of meson pairs produced with quantum correlations gives direct access to parameters that are challenging to measure in other systems. In this Letter, the existence of quantum correlations due to charge-conjugation symmetry C are demonstrated in DD¯ pairs produced through the processes e+e-→DD¯, e+e-→D∗D¯, and e+e-→D∗D¯∗, where the lack of charge superscripts refers to an admixture of neutral-charm-meson particle and antiparticle states, using 7.13 fb-1 of e+e- collision data collected by the BESIII experiment between center-of-mass energies of 4.13-4.23 GeV. Processes with either C-even or C-odd constraints are identified and separated. A procedure is presented that harnesses the entangled production process to enable measurements of D0-meson hadronic parameters. This Letter provides the first confirmation of quantum correlations in e+e-→XDD¯ processes and the first observation of a C-even constrained DD¯ system. The procedure is applied to measure δKπD, the strong phase between the D0→K-π+ and D¯0→K-π+ decay amplitudes, which results in the determination of (Formula presented). The potential for measurements of other hadronic decay parameters and charm mixing with these and future datasets is also discussed.

AB - The study of meson pairs produced with quantum correlations gives direct access to parameters that are challenging to measure in other systems. In this Letter, the existence of quantum correlations due to charge-conjugation symmetry C are demonstrated in DD¯ pairs produced through the processes e+e-→DD¯, e+e-→D∗D¯, and e+e-→D∗D¯∗, where the lack of charge superscripts refers to an admixture of neutral-charm-meson particle and antiparticle states, using 7.13 fb-1 of e+e- collision data collected by the BESIII experiment between center-of-mass energies of 4.13-4.23 GeV. Processes with either C-even or C-odd constraints are identified and separated. A procedure is presented that harnesses the entangled production process to enable measurements of D0-meson hadronic parameters. This Letter provides the first confirmation of quantum correlations in e+e-→XDD¯ processes and the first observation of a C-even constrained DD¯ system. The procedure is applied to measure δKπD, the strong phase between the D0→K-π+ and D¯0→K-π+ decay amplitudes, which results in the determination of (Formula presented). The potential for measurements of other hadronic decay parameters and charm mixing with these and future datasets is also discussed.

UR - https://www.scopus.com/pages/publications/105021069413

U2 - 10.1103/dkgg-9twj

DO - 10.1103/dkgg-9twj

M3 - Article

VL - 135

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 17

M1 - 171901

ER -