Korea University, Seoul.
Phys Rev Lett. 2011 Nov 25;107(22):221801. doi: 10.1103/PhysRevLett.107.221801. Epub 2011 Nov 21.
We report the first observation of the doubly Cabibbo-suppressed decays D(+)→K(+)η((')) using a 791 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The ratio of the branching fractions of doubly Cabibbo-suppressed relative to singly Cabibbo-suppressed D(+)→π(+)η((')) decays are B(D(+)→K(+)η)/B(D(+)→π(+)η)=(3.06±0.43±0.14)% and B(D(+)→K(+)η')/B(D(+)→π(+)η')=(3.77±0.39±0.10)%. From these, we find that the relative final-state phase difference between the tree and annihilation amplitudes in D(+) decays, δ(TA), is (72±9)° or (288±9)°. We also report the most precise measurements of CP asymmetries to date: A(CP)(D(+)→π(+)η)=(+1.74±1.13±0.19)% and A(CP)(D(+)→π(+)η')=(-0.12±1.12±0.17)%.
我们报道了首次观察到双重 Cabibbo 抑制衰变 D(+)→K(+)η(('))，使用 Belle 探测器在 KEKB 不对称能电子-正电子对撞机上采集的 791 fb(-1)数据样本。双重 Cabibbo 抑制相对于单重 Cabibbo 抑制 D(+)→π(+)η(('))衰变的分支比为 B(D(+)→K(+)η)/B(D(+)→π(+)η)=(3.06±0.43±0.14)%，B(D(+)→K(+)η')/B(D(+)→π(+)η')=(3.77±0.39±0.10)%。由此，我们发现 D(+)衰变中树和湮灭振幅的相对末态相位差 δ(TA)为 (72±9)°或 (288±9)°。我们还报告了迄今为止对 CP 不对称性的最精确测量：A(CP)(D(+)→π(+)η)= (+1.74±1.13±0.19)%和 A(CP)(D(+)→π(+)η')=(-0.12±1.12±0.17)%。
