We present a measurement of the branching fraction and time-dependent charge-parity (CP) decay-rate asymmetries in B0→J/ψπ0 decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric e+e- collider in 2019-2022 and contains (387±6)×106 BB¯ meson pairs from ϒ(4S) decays. We reconstruct 392±24 signal decays and fit the CP parameters from the distribution of the proper-decay-time difference of the two B mesons. We measure the branching fraction to be (B0→J/ψπ0)=(2.00±0.12±0.09)×10-5 and the direct and mixing-induced CP asymmetries to be CCP=0.13±0.12±0.03 and SCP=-0.88±0.17±0.03, respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced CP violation with a significance of 5.0 standard deviations for the first time in this mode.

Observation of time-dependent CP violation and measurement of the branching fraction of B0 →j/ψπ0 decays / Adachi, I., Aggarwal, L., Ahmed, H., Aihara, H., Akopov, N., Aloisio, A., Althubiti, N., Anh Ky, N., Asner, D.M., Atmacan, H., Aushev, V., Aversano, M., Ayad, R., Babu, V., Bae, H., Baghel, N.K., Bahinipati, S., Bambade, P., Banerjee, S., Bansal, S., et al.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 111:1(2025). [10.1103/PhysRevD.111.012011]

Observation of time-dependent CP violation and measurement of the branching fraction of B0 →j/ψπ0 decays

Aloisio A.;Campajola M.;De Nardo G.;Di Capua F.;Gaudino G.;Giordano R.;Merola M.;Mirra M.;Pardi S.;
2025

Abstract

We present a measurement of the branching fraction and time-dependent charge-parity (CP) decay-rate asymmetries in B0→J/ψπ0 decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric e+e- collider in 2019-2022 and contains (387±6)×106 BB¯ meson pairs from ϒ(4S) decays. We reconstruct 392±24 signal decays and fit the CP parameters from the distribution of the proper-decay-time difference of the two B mesons. We measure the branching fraction to be (B0→J/ψπ0)=(2.00±0.12±0.09)×10-5 and the direct and mixing-induced CP asymmetries to be CCP=0.13±0.12±0.03 and SCP=-0.88±0.17±0.03, respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced CP violation with a significance of 5.0 standard deviations for the first time in this mode.
2025
Observation of time-dependent CP violation and measurement of the branching fraction of B0 →j/ψπ0 decays / Adachi, I., Aggarwal, L., Ahmed, H., Aihara, H., Akopov, N., Aloisio, A., Althubiti, N., Anh Ky, N., Asner, D.M., Atmacan, H., Aushev, V., Aversano, M., Ayad, R., Babu, V., Bae, H., Baghel, N.K., Bahinipati, S., Bambade, P., Banerjee, S., Bansal, S., et al.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 111:1(2025). [10.1103/PhysRevD.111.012011]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/1011941
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