ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2013, vol. 88, p. -
Evidence for the suppressed decay B-→DK-, D→K+ π-π0
We report a study of the suppressed decay B-→DK -, D→K+π-π0, where D denotes either a D0 or a D̄0 meson. The decay is sensitive to the CP -violating parameter 3. Using a data sample of 772×106 BB̄ pairs collected at the Υ(4S) resonance with the Belle detector, we measure the ratio of branching fractions of the above suppressed decay to the favored decay B-→DK-, D→K-π+π0. Our result is RDK=[1.98±0.62(stat)±0.24(syst)] ×10-2, which indicates the first evidence of the signal for this suppressed decay with a significance of 3.2 standard deviations. We measure the direct CP asymmetry between the suppressed B- and B+ decays to be ADK=0.41±0.30(stat)±0.05(syst). We also report measurements for the analogous quantities RDπ and A Dπ for the decay B-→Dπ-, D→K+π-π0. © 2013 American Physical Society.