phi1 Measurements at Belle

Abstract

We present the recent measurements of the B0 -> eta' K0 and the B -> omega K decay modes based on the full data set of 772x10^6 BBbar pairs collected by the Belle detector at the KEKB e+e- collider. In the B0 -> eta' K^{0} mode, we obtain the CP-violating parameters A(eta'K0) = +0.03+/-0.05(stat)+/-0.04(syst), S(eta'K0) = +0.68+/-0.07(stat)+/-0.03(syst). This is the world's most precise result on the eta' K0 CP parameters. In B -> omega K decays, we measure the branching fractions B(B0 -> omega K0) = (4.5+/-0.4(stat)+/-0.3(syst))x10^-6, B(B- -> omega K-) = (6.8+/-0.4(stat)+/-0.4(syst))x10^-6, which are their current most precise results. We measure the first evidence of CP violation in the B0 -> omega K0S decay mode, obtaining the CP-violating parameters A(omega K0S} = -0.36+/-0.19(stat)+/-0.05(syst), S(omega K0S} = +0.91+/-0.32(stat)+/-0.05(syst). In the B- -> omega K- mode, we measure the direct CP-violation parameter A(omega K-) = -0.03+/-0.04(stat)+/-0.01(syst), which is its most precise measurement to date.