We present a measurement of the branching fraction and fraction of longitudinal polarization of B0→ρ+ρ- decays, which have two π0's in the final state. We also measure time-dependent CP violation parameters for decays into longitudinally polarized ρ+ρ- pairs. This analysis is based on a data sample containing (387±6)×106 ϒ(4S) mesons collected with the Belle II detector at the SuperKEKB asymmetric-energy e+e- collider in 2019-2022. We obtain B(B0→ρ+ρ-)=(2.89-0.22+0.23 -0.27+0.29)×10-5, fL=0.921-0.025+0.024 -0.015+0.017, S=-0.26±0.19±0.08, and C=-0.02±0.12-0.05+0.06, where the first uncertainties are statistical and the second are systematic. We use these results to perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle φ2 and obtain two solutions; the result consistent with other Standard Model constraints is φ2=(92.6-4.7+4.5)°.

Measurement of the branching fraction, polarization, and time-dependent CP asymmetry in B0 →ρ+ρ- decays and constraint on the CKM angle φ2 / Adachi, I., Aggarwal, L., Ahmed, H., Akopov, N., Alhakami, M., Aloisio, A., Althubiti, N., Anh Ky, N., Asner, D.M., Atmacan, H., Aushev, V., Aversano, M., Ayad, R., Babu, V., Baghel, N.K., Bambade, P., Banerjee, S., Barrett, M., Bartl, M., Baudot, J., et al.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 111:9(2025). [10.1103/PhysRevD.111.092001]

Measurement of the branching fraction, polarization, and time-dependent CP asymmetry in B0 →ρ+ρ- decays and constraint on the CKM angle φ2

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 fraction of longitudinal polarization of B0→ρ+ρ- decays, which have two π0's in the final state. We also measure time-dependent CP violation parameters for decays into longitudinally polarized ρ+ρ- pairs. This analysis is based on a data sample containing (387±6)×106 ϒ(4S) mesons collected with the Belle II detector at the SuperKEKB asymmetric-energy e+e- collider in 2019-2022. We obtain B(B0→ρ+ρ-)=(2.89-0.22+0.23 -0.27+0.29)×10-5, fL=0.921-0.025+0.024 -0.015+0.017, S=-0.26±0.19±0.08, and C=-0.02±0.12-0.05+0.06, where the first uncertainties are statistical and the second are systematic. We use these results to perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle φ2 and obtain two solutions; the result consistent with other Standard Model constraints is φ2=(92.6-4.7+4.5)°.
2025
Measurement of the branching fraction, polarization, and time-dependent CP asymmetry in B0 →ρ+ρ- decays and constraint on the CKM angle φ2 / Adachi, I., Aggarwal, L., Ahmed, H., Akopov, N., Alhakami, M., Aloisio, A., Althubiti, N., Anh Ky, N., Asner, D.M., Atmacan, H., Aushev, V., Aversano, M., Ayad, R., Babu, V., Baghel, N.K., Bambade, P., Banerjee, S., Barrett, M., Bartl, M., Baudot, J., et al.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 111:9(2025). [10.1103/PhysRevD.111.092001]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/1012042
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