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Register a new userMeasurements of the absolute branching fractions and $CP$ asymmetries for $D^+rightarrow K_{S,L}^0 K^+(pi^0)$
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Using $e^+e^-$ collision data corresponding to an integrated luminosity of 2.93 fb$^{-1}$ taken at a center-of-mass energy of 3.773 GeV with the BESIII detector, we determine the absolute branching fractions $mathcal{B}(D^+rightarrow K_S^0 K^+)$ = $(3.02 pm 0.09 pm 0.08)times10^{-3}$, $mathcal{B}(D^+rightarrow K_S^0 K^+ pi^0)$ = $(5.07 pm 0.19 pm 0.23)times10^{-3}$, $mathcal{B}(D^+rightarrow K_L^0 K^+)$ = $(3.21 pm 0.11 pm 0.11)times10^{-3}$, and $mathcal{B}(D^+rightarrow K_L^0 K^+ pi^0)$ = $(5.24 pm 0.22 pm 0.22)times10^{-3}$, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction wbrksk is consistent with the world average value and the other three branching fractions are measured for the first time. We also measure the $CP$ asymmetries for the four decays and do not find a significant deviation from zero.
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We report measurements of the branching fractions and $CP$ asymmetries for $D_s^{+} rightarrow K^{+} eta $, $D_s^{+} rightarrow K^{+} pi^0 $, and $D_s^{+} rightarrow pi^{+} eta $ decays, and the branching fraction for $D_s^{+} rightarrow pi^{+} pi^0$. Our results are based on a data sample corresponding to an integrated luminosity of 921 fb$^{-1}$ collected by the Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. Our measurements of $CP$ asymmetries in these decays are the most precise to-date; no evidence for $CP$ violation is found.
Using an $e^{+}e^{-}$ annihilation data sample corresponding to an integrated luminosity of $3.19~mathrm{fb}^{-1}$ and collected at a center-of-mass energy $sqrt{s} = 4.178~mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fractions $mathcal{B}(D_{s}^{+} rightarrow K_{S}^{0}K^{+}) = (1.425pm0.038_{rm stat.}pm0.031_{rm syst.})%$ and $mathcal{B}(D_{s}^{+} rightarrow K_{L}^{0}K^{+}) =(1.485pm0.039_{rm stat.}pm0.046_{rm syst.})%$. The branching fraction of $D_{s}^{+} rightarrow K_{S}^{0}K^{+}$ is compatible with the world average and that of $D_{s}^{+} rightarrow K_{L}^{0}K^{+}$ is measured for the first time. We present the first measurement of the $K_{S}^{0}$-$K_{L}^{0}$ asymmetry in the decays $D_{s}^{+} rightarrow K_{S,L}^{0}K^{+}$, and $R(D_{s}^{+} rightarrow K_{S,L}^{0}K^{+})=frac{mathcal{B}(D_{s}^{+} rightarrow K_{S}^{0}K^{+}) -mathcal{B}(D_{s}^{+} rightarrow K_{L}^{0}K^{+})}{mathcal{B}(D_{s}^{+} rightarrow K_{S}^{0}K^{+}) +mathcal{B}(D_{s}^{+} rightarrow K_{L}^{0}K^{+})}= (-2.1pm1.9_{rm stat.}pm1.6_{rm syst.})%$. In addition, we measure the direct $CP$ asymmetries $A_{rm CP}(D_{s}^{pm} rightarrow K_{S}^{0}K^{pm}) = (0.6pm2.8_{rm stat.}pm0.6_{rm syst.})%$ and $A_{rm CP}(D_{s}^{pm} rightarrow K_{L}^{0}K^{pm}) = (-1.1pm2.6_{rm stat.}pm0.6_{rm syst.})%$.
A search for CP violation in $D^0 rightarrow K^{-} K^{+} $ and $D^0 rightarrow pi^{-} pi^{+} $ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of $3~fb^{-1}$, collected using the LHCb detector at centre-of-mass energies of 7 and $8~$TeV. The flavour of the charm meson is inferred from the charge of the pion in $D^{*+}rightarrow D^0pi^+$ and $D^{*-}rightarrow bar{D^0}pi^{-}$ decays. The difference between the CP asymmetries in $D^0 rightarrow K^{-} K^{+} $ and $D^0 rightarrow pi^{-} pi^{+} $ decays, $Delta A_{CP} equiv A_{CP}(K^{-} K^{+}) - A_{CP}(pi^{-} pi^{+})$, is measured to be $left( -0.10 pm 0.08(stat) pm 0.03(syst) right) %$. This is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment.
We report updated measurements of branching fractions ($mathcal{B}$) and CP-violating charge asymmetries ($mathcal{A_{rm CP}}$) for charmless $B$ decays at Belle II, which operates on or near the $Upsilon$(4S) resonance at the SuperKEKB asymmetric energy $e^{+}e^{-}$ collider. We use samples of 2019 and 2020 data corresponding to 62.8 fb$^{-1}$ of integrated luminosity. The samples are analysed using two-dimensional fits in $Delta E$ and $M_{it bc}$ to determine signal yields of approximately 568, 103, and 115 decays for the channels $B^0 to K^+pi^-$, $B^+ to K_{rm S}^0pi^+$, and $B^0 to pi^+pi^-$, respectively. Signal yields are corrected for efficiencies determined from simulation and control data samples to obtain branching fractions and CP-violating asymmetries for flavour-specific channels. The results are compatible with known determinations and contribute important information to an early assessment of Belle II detector performance.
Time-integrated $CP$ asymmetries in $D^0$ decays to the final states $K^- K^+$ and $pi^- pi^+$ are measured using proton-proton collisions corresponding to $3mathrm{,fb}^{-1}$ of integrated luminosity collected at centre-of-mass energies of $7mathrm{,Tekern -0.1em V}$ and $8mathrm{,Tekern -0.1em V}$. The $D^0$ mesons are produced in semileptonic $b$-hadron decays, where the charge of the accompanying muon is used to determine the initial flavour of the charm meson. The difference in $CP$ asymmetries between the two final states is measured to be begin{align} Delta A_{CP} = A_{CP}(K^-K^+)-A_{CP}(pi^-pi^+) = (+0.14 pm 0.16mathrm{,(stat)} pm 0.08mathrm{,(syst)})% . onumber end{align} A measurement of $A_{CP}(K^-K^+)$ is obtained assuming negligible $CP$ violation in charm mixing and in Cabibbo-favoured $D$ decays. It is found to be begin{align} A_{CP}(K^-K^+) = (-0.06 pm 0.15mathrm{,(stat)} pm 0.10mathrm{,(syst)}) % , onumber end{align} where the correlation coefficient between $Delta A_{CP}$ and $A_{CP}(K^-K^+)$ is $rho=0.28$. By combining these results, the $CP$ asymmetry in the $D^0rightarrowpi^-pi^+$ channel is $A_{CP}(pi^-pi^+)=(-0.20pm0.19mathrm{,(stat)}pm0.10mathrm{,(syst)})%$.
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