We present a measurement of the branching fraction for the Cabibbo- and color-suppressed $B^0 \to χ_{c1}π^0$ decay based on a data sample of $657\times 10^6$ $B\bar B$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe a signal of $40\pm9$ events with a significance of $4.7σ$ including systematic uncertainties. The measured branching fraction is $\mathcal {B}(B^0 \to χ_{c1} π^0) = (1.12\pm 0.25(\rm {stat.})\pm 0.12({\rm syst.}))\times 10^{-5}$.
We measure the branching fraction for the Singly Cabibbo-suppressed decay $D^0\rightarrow K^0_S\,K^0_S\,π^+π^-$, and we search for $CP$ violation via a measurement of the $CP$ asymmetry $A^{}_{CP}$ and also the $T$-odd triple-product asymmetry $a_{CP}^{T}$. The later two measurements are complementary. We use 922~fb$^{-1}$ of data recorded by the Belle experiment, which ran at the KEKB asymmetric-energy $e^+ e^-$ collider. The branching fraction is measured relative to the Cabibbo-favored normalization channel $D^0\rightarrow K^0_S\,π^+π^-$. Singly Cabibbo-suppressed charm decays are expected …
The Belle II collaboration operates a substantially upgraded Belle detector at the SuperKEKB energy-asymmetric e+ e- collider. Belle II will start recording collisions at the Upsilon(4S) energy in 2018, aiming to collect by 2025 50 ab^{-1} of data, 50 times more than the Belle experiment. We report prospects for measuring quantities associated with charge-parity violation, with special emphasis on the Cabibbo-Kobayashi-Maskawa angle phi_3 (gamma) and observables in semileptonic B meson decays associated with the quark-mixing matrix element Vub.
Cabibbo-Suppressed Decays of D^+ to pi^+ pi^0, K^+ K^0, and K^+ pi^0
利用CLEO II和II.V探测器收集的对应于13.7 fb^-1的数据样本，我们报告了对D^+介子的两种Cabibbo抑制衰变模式的新的分支分数测量结果：Br（D^+ to pi^+ pi^0）=（1.3 +/- 0.2）x 10^-3和Br（D^+ to \bar{K}^0 K^+）=（5.2 +/- 0.6）x 10^-3，这是对过去测量的显著改进。误差包括统计和系统的不确定性，以及绝对D^+分支分数尺度的不确定性。我们还设定了第一个90%置信水平的上限，即卡比博双重抑制衰变模式的分支分数Br（D^+ to K^+ pi ^0）< 4.2 x 10^-4。
Using $2.93 \rm fb^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the doubly Cabibbo-suppressed decay $D^+\to K^+π^+π^-π^0$ is reported. After removing decays that contain narrow intermediate resonances, including $D^+\to K^+η$, $D^+\to K^+ω$, and $D^+\to K^+ϕ$, the branching fraction of the decay $D^+\to K^+π^+π^-π^0$ is measured to be $(1.13 \pm 0.08_{\rm stat} \pm 0.03_{\rm syst})\times 10^{-3}$. The ratio of branching fractions of $D^+\to K^+π^+π^-π^0$ over $D^+\to K^-π^+π^+π^0$ is found to be $(1.81\pm0…
We report a measurement of the branching fraction of inclusive semileptonic $B$ meson decays $B\to X_c\ellν\ell$ in $Υ(4S)\to B\bar B$~data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e^+e^-$ collider and corresponding to 62.8 fb$^{-1}$ of integrated luminosity. Only a charged lepton (electon or muon) is reconstructed and the signal yield is determined from a fit to the lepton momentum distribution in the center-of-mass frame of the colliding beams. Averaging the result in the electron and muon channels, we find ${\cal B}(B\to X_c\ellν_\ell) = (9.75\pm 0.03(\text{st…
We report a measurement of the branching fraction of the semileptonic decay B- -> D0 l- nubar_l (and its charge conjugate) using 62.8/fb of Upsilon(4S) -> B Bbar data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy e+ e- collider. The neutral charm meson is searched for in the decay mode D0 -> K- pi+ and combined with a properly charged identified lepton (electron or muon) to reconstruct this decay. No reconstruction of the second B meson in the Upsilon(4S) event is performed. We obtain Br( B- -> D0 l- nubar_l ) = (2.29 +/- 0.05(stat) +/- 0.08(syst))%, in agreement with …
We search for the singly Cabibbo-suppressed decay $D^+ \to K^- K^0_s π^+ π^+ π^0$ using the full data set of 988 fb$^{-1}$ recorded by the Belle experiment at the KEKB $e^+e^-$ collider. We measure the branching fraction for this decay to be $\left({6.4^{+3.9}_{-3.8}}\right)\times10^{-5}$ with an upper limit at 95% credibility of $1.4\times10^{-4}$. We also measure the sum of the branching fractions for $D^+ \to \bar{K}^* ηπ^+$ and $D^+ \to \bar{K}^* ωπ^+$ to be $\left({6.0^{+6.3}_{-5.8}}\right) \times {10^{-5}}$ with an upper limit at 95% credibility of $1.8\times10^{-4}$.
Hadronic $B$ decays without a charm quark constitute a powerful probe to search for physics beyond the standard model as well as to provide constraints on $CP$ violation parameters. We report final measurements from Belle of the branching fractions and $CP$ asymmetries for the decays $B^{0} \rightarrow π^{0} π^{0}$ and $B^{\pm} \rightarrow K^{+} K^{-} π^{\pm}$. The $B^{0} \rightarrow π^{0} π^{0}$ measurements enable us to improve constraints on the angle $ϕ_{2}$ of the CKM unitarity triangle. For $B^{\pm} \rightarrow K^{+} K^{-} π^{\pm}$ we measure $CP$ asymmetry as a function of the invariant…
It is experimentally observed that ratios of branching fractions for semitauonic and semileptonic $B$ decays, known as the $R(D^{(*)})$, are higher than Standard Model (SM) predictions. The $B \to \bar{D}^{(*)} τ^{+} ν_τ$ decays, except for the branching fractions, offer also other observables, in particular, angular observables may determine spin structure of a potential New Physics (NP) providing some clues to explain the $R(D^{(*)})$ puzzle. In this review, polarization measurements in $B \to \bar{D}^{*} τ^{+} ν_τ$ decays at Belle are presented and prospects for measurements of characterist…
We report the recent results related to $π-K$ interactions based on the data collected by the Belle experiment at the KEKB collider. This includes the branching fraction and $CP$ asymmetry measurements of $B^+\to K^+K^-π^+$ decay, search for the $Λ_c^+\toϕpπ^0$, $Λ_c^+\to P_s^+π^0$ decays, branching fraction measurement of $Λ_c^+\to K^-π^+pπ^0$, first observation of doubly Cabibbo-suppressed decay $Λ_c^+\to K^+π^-p$, and the measurement of CKM angle $ϕ_3$ ($γ$) with a model-independent Dalitz plot analysis of $B^{\pm}\to DK^{\pm},D\to K_S^0π^+π^-$ decay.
We report on the first Belle II measurements of branching fractions and CP-violating charge asymmetries in charmless $B$ decays. We use 34.6 fb$^{-1}$ from electron-positron collisions collected in 2019 and 2020 at the $Υ(4S)$ resonance. The results are compatible with known values and show performance already comparable with Belle.
We report the results on $D^0$-$\bar{D}^0$ mixing in the decays of $D^0\to K^+π^-$ and $D^0\to K_S^0π^+π^-$, and CP violation in $D^0\toπ^0π^0$ using a data sample with an integrated luminosity of about 1~ab$^{-1}$ recorded with the Belle detector, at different center of mass energies. The mixing is observed in $D^0\to K^+π^-$ with the mixing parameters $x'^2=(0.09\pm 0.22)\times 10^{-3}$, $y'=(4.6\pm 3.4)\times 10^{-3}$ and the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates $R_{D}=(3.53\pm0.13)\times 10^{-3}$, where the quoted uncertainties combine both statistical and syst…
This proceeding summarizes the recent measurements of semileptonic $b\to u$ decays from the Belle experiment. These analyses use the full data set collected at the $Υ(4S)$ resonance at KEKB accelerator complex with a center-of-mass energy of $\sqrt{s} = 10.58$ GeV, which contains an integrated luminosity of 711 fb$^{-1}$ and corresponds to 772 million $Υ(4S) \to B\bar{B}$ events. In the sector of inclusive decay, the partial branching fraction of $B \to X_{u} \ell ν$ decays and the CKM matrix element $|V_{ub}|$ are measured with hadronic tagging. The first measurement of differential branching…
Measurements of $\boldsymbol{B\rightarrow Kπ}$ and $\boldsymbol{B\rightarrow ππ}$ Branching Fractions and $\boldsymbol{\mathcal{A}_{CP}}$ Asymmetries at Belle II
Belle II 测量了多种 $B\to K\pi$ 和 $B\to\pi\pi$ 衰变的分支比及直接 CP 不对称性，通过同位旋求和规则检验标准模型，并测量了 CKM 角 $\phi_2$ 相关的衰变，结果与标准模型预期一致。
