arXiv subjects

Y. Chao

Publications and source records attributed to Y. Chao.

41 records · Page 3Linked to original sources

arXiv2006

Direct CP Violation in Charmless B Decays

We report the updated results of direct CP violation measurements from Belle and BaBar for the following modes: B -> h+h-/h+-pi^0, B -> eta(') h+- and B -> K+-pi+-pi-+, where h stands for a charged kaon or pion. The data used in these studies are up to 386 million BBbar pairs for Belle and 232 million BBbar pairs for BaBar. The current significant measurements include: Acp(B -> K+ pi-)=-0.108+/-0.016, Acp(B -> rho0(770) K+)=0.31+0.11-0.10, and Acp(B -> eta K+)=-0.33+/-0.12.

hep-ex↗

arXiv2004

Observation of B0->pi0pi0

We report the first observation of the decay B0->pi0pi0, using a 253/fb data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. The measured branching fraction is BF(B0->pi0pi0) = {2.32 +0.4-0.5(stat) +0.2-0.3(syst)} x 10^-6, with a significance of 5.8 standard deviations including systematic uncertainties. We also make the first measurement of the direct CP violating asymmetry in this mode.

hep-ex↗

arXiv2004

Evidence for Direct CP Violation in B0 -> K+- pi-+ Decays

We report evidence for direct CP violation in the decay B0 -> K+-pi-+ with 253/fb of data collected with the Belle detector at the KEKB e+e- collider. Using 275 million B B_bar pairs we observe a B -> K+-pi-+ signal with 2140+-53 events. The measured CP violating asymmetry is Acp(K+-pi-+) = -0.101+-0.025 (stat)+-0.005 (syst), corresponding to a significance of 3.9 sigma including systematics. We also search for CP violation in the decays B+- -> K+-pi0 and B+- -> pi+-pi0. The measured CP violating asymmetries are Acp(K+-pi0) = 0.04+-0.05(stat)+-0.02(syst) and Acp(pi+-pi0) = -0.02+-0.10(stat)+-0.01(syst), corresponding to the intervals -0.05 < Acp(K+-pi0) < 0.13 and -0.18<Acp(pi+-pi0)<0.14 at 90% confidence level.

hep-ex↗

arXiv2004

Improved Measurements of Partial Rate Asymmetry in B -> h h Decays

We report improved measurements of the partial rate asymmetry (Acp) in B -> h h decays with 140fb^-1 of data collected with the Belle detector at the KEKB e+e- collider. Here h stands for a charged or neutral pion or kaon and in total five decay modes are included: K-+ pi+-, K0s pi-+, K-+ pi0, pi-+ pi0 and K0s pi0. The flavor of the last decay mode is determined from the accompanying B meson. Using a data sample 4.7 times larger than that of our previous measurement, we find Acp(K-+ pi+-) -0.088+-0.035+-0.013, 2.4 sigma from zero. Results for other decay modes are also presented.

hep-ex↗

arXiv2004

Improved Measurements of Branching Fractions for B->Kpi, pipi and KK Decays

We report improved measurements of branching fractions for $B\to Kπ$, $π^+π^-$, $π^+π^0$ and $K\bar{K}$ decays based on a data sample of 85.0 million $B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ storage ring. This data sample is almost three times larger than the sample previously used. We observe clear signals for $B\to Kπ$, $π^+π^-$ and $π^+π^0$ decays and set upper limits on $B\to K\bar{K}$ decays. The results can be used to give model-dependent constraints on the CKM angle $ϕ_3$, as well as limits on the hadronic uncertainty in the time-dependent analysis of the angle $ϕ_2$.

hep-ex↗