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

Dorigo, M.;Gabrielli, A.;Ganiev, E.;Ghosh, D.;Lanceri, L.;Manfredi, R.;Mantovano, M.;Raiz, S.;Vitale, L.;
2025-01-01

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
Pubblicato
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/3121584
 Avviso

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 1
  • ???jsp.display-item.citation.isi??? 1
social impact