ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2010, vol. 81, p. -
Evidence for direct CP violation in the decay B±→ D(*)K±, D→KS0π+π - and measurement of the CKM phase φ3
We present a new measurement of the unitarity triangle angle φ3 using a Dalitz plot analysis of the KS0π+π- decay of the neutral D meson produced in B±→D(*) K± decays. The method exploits the interference between D0 and D̄0 to extract the angle φ3, strong phase δ, and the ratio r of suppressed and allowed amplitudes. We apply this method to a 605fb-1 data sample collected by the Belle experiment. The analysis uses three decays: B±→DK±, and B ±→D*K± with D *→Dπ0 and D*→Dγ, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the three modes, we obtain φ3=78.4°+10.8°-11. 6°±3.6°(syst)±8.9°(model). CP conservation in this process is ruled out at the confidence level (1-CL)=5×10-4, or 3.5 standard deviations. © 2010 The American Physical Society.