arXiv subjects
Publications and source records attributed to B. R. Ko.
We present the result of a search for charge asymmetry in B^+ -> J/psi K^+ decays. The CP-violating charge asymmetry is measured to be A_CP(B^+ -> J/psi K^+) = [-0.76 +/- 0.50 (stat) +/- 0.22 (syst)]%.
We report a first measurement of inclusive B -> X_s eta decays, where X_s is a charmless state with unit strangeness. The measurement is based on a pseudo-inclusive reconstruction technique and uses a sample of 657 x 10^6 BB-bar pairs accumulated with the Belle detector at the KEKB e^+e^- collider. For M_{X_s} < 2.6 GeV/c^2, we measure a branching fraction of (26.1 +/- 3.0 (stat) +1.9 -2.1 (syst) +4.0 -7.1 (model)) x 10^-5 and a direct CP asymmetry of A_{CP} = -0.13 +/- 0.04 +0.02 -0.03. Over half of the signal occurs in the range M_{X_s} > 1.8 GeV/c^2.
We have searched for CP violation in the charmed meson decays $D^{+}_{(s)}\to K^0_Sπ^+$ and $D^{+}_{(s)}\to K^0_S K^+$ using 673 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. No evidence for CP violation is observed. We report the most sensitive CP asymmetry measurements to date for these decays: $A_{CP}^{D^+\to K^0_Sπ^+}=(-0.71\pm0.19\pm0.20)%$, $A_{CP}^{D^+_s\to K^0_Sπ^+}=(+5.45\pm2.50\pm0.33)%$, $A_{CP}^{D^+\to K^0_S K^+}=(-0.16\pm0.58\pm0.25)%$, and $A_{CP}^{D^+_s\to K^0_S K^+}=(+0.12\pm0.36\pm0.22)%$, where the first uncertainties are statistical and the second are systematic.
We report an improved measurement of $D^+ \to K_S^0 K^+$ and $D^+_s\to K_S^0 π^+$ branching ratios using 605 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The measured branching ratios with respect to the Cabibbo-favored modes are $\mathcal{B}(D^+ \to K_S^0 K^+)/\mathcal{B}(D^+ \to K_S^0 π^+)$ = 0.1899$\pm0.0011\pm$0.0022 and $\mathcal{B}(D^+_s \to K_S^0 π^+)/\mathcal{B}(D^+_s \to K_S^0 K^+)$ = 0.0803$\pm0.0024\pm$0.0019 where the first uncertainties are statistical and the second are systematic.
We report the first observation of the doubly Cabibbo-suppressed decay, $D^{+}_{s} \to K^{+}K^{+}π^{-}$ and the significantly improved measurement of the doubly Cabibbo-suppressed decay, $D^{+} \to K^{+}π^{+}π^{-}$ using $\textrm{605 fb}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The branching ratio with respect to its Cabibbo-favored counterpart are $\mathcal{B}(D^{+}_{s} \to K^{+}K^{+}π^{-})/\mathcal{B}(D^{+}_{s} \to K^{+}K^{-}π^{+}) = 0.229\pm0.028\pm0.012)%$ and $\mathcal{B}(D^{+} \to K^{+}π^{+}π^{-})/\mathcal{B}(D^{+} \to K^{-}π^{+}π^{+}) = (0.569\pm0.018\pm0.014)%$, where the first uncertainties are statistical and the second is systematic. We also report the improved measurement of $D^{+} \to K^{0}_{S}K^{+}$ and $D^{+}_{s} \to K^{0}_{S}π^{+}$ branching ratios using the same amount of data samples. The measured branching ratios with respect to the Cabibbo-favored modes are $\mathcal{B}(D^{+} \to K^{0}_{S}K^{+})/\mathcal{B}(D^{+} \to K^{0}_{S}π^{+}) = (0.1899\pm0.0011\pm0.0018)$ and $\mathcal{B}(D^{+}_{s} \to K^{0}_{S}π^{+})/\mathcal{B}(D^{+}_{s} \to K^{0}_{S}K^{+}) = (0.0803\pm0.0024\pm0.0012)$.
We report the first observation of the doubly Cabibbo-suppressed decay $D^+_s\to K^+K^+π^-$ using 605 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching ratio with respect to its Cabibbo-favored counterpart $\mathcal{B}(D^+_s\to K^+K^+π^-)$ / $\mathcal{B}(D^+_s\to K^+K^-π^+)$ is (0.229$\pm0.028\pm$0.012)%, where the first uncertainty is statistical and the second is systematic. We also report a significantly improved measurement of the doubly Cabibbo-suppressed decay $D^+\to K^+π^+π^-$, with a branching ratio $\mathcal{B}(D^+\to K^+π^+π^-)$ / $\mathcal{B}(D^+\to K^-π^+π^+)$=(0.569$\pm0.018\pm$0.014)%.