First measurement of the CKM angle φ 3 with B ± → D ( K 0S π + π − π 0 ) K ± decays The Belle Collaboration

: We present the first model-independent measurement of the CKM unitarity triangle angle φ 3 using B ± → D ( K 0S π + π − π 0 ) K ± decays, where D indicates either a D 0 or D 0 meson. Measurements of the strong-phase difference of the D → K 0S π + π − π 0 amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of 772 × 10 6 BB events collected at the Υ(4 S ) resonance. We obtain φ 3 = (5 . 7 +10 . 2 − 8 . 8 ± 3 . 5 ± 5 . 7) ◦ and the suppressed amplitude ratio r B = 0 . 323 ± 0 . 147 ± 0 . 023 ± 0 . 051 . Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on φ 3 is ( − 29 . 7 , 109 . 5) ◦ , which is consistent with the current world average.