Measurements of the Branching Fraction, Polarization, and CP Asymmetry for the Decay B0→ωω

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We present a comprehensive study of B⁰→ωω decays using 772×10⁶ BB[over ¯] pairs collected with the Belle detector at the KEKB e⁺e⁻ collider. This process is a suppressed charmless decay into two vector mesons and can exhibit interesting polarization and CP violation. The decay is observed for the first time with a significance of 7.9 standard deviations. We measure a branching fraction B=(1.53±0.29±0.17)×10⁻⁶, a fraction of longitudinal polarization fL=0.87±0.13±0.13, and a time-integrated CP asymmetry ACP=-0.44±0.43±0.11, where the first uncertainties listed are statistical and the second are systematic. This is the first observation of B⁰→ωω and the first measurements of fL and ACP for this decay.