In spite of the fact that the two-body $B$ decays into $χ_{c2}$ such as $B \to χ_{c2} K^{(*)}$ are suppressed by the QCD factorization effect, the inclusive $B \to χ_{c2} X$ branching fraction amounts to one third of the non-suppressed $B \to χ_{c1} X$ decays because of the decay modes to the multi-body final states. Using a large statistics $Υ(4S)$ data sample corresponding to 772 million $B$ meson pairs accumulated by the Belle detector at the KEKB $e^+e^-$ collider, precise measurements of inclusive $B \to χ_{c1}$ and $χ_{c2}$ branching fractions are carried out. The multi-body final states such as $χ_{cJ} K π$, $χ_{cJ} K ππ$ and so on are also investigated to look for new charmonium-like resonance.
We report on the measurement of inclusive charmless semileptonic B decays $B \to X_{u} \ell ν$. The analysis makes use of hadronic tagging and is performed on the full data set of the Belle experiment comprising 772 million $B\bar{B}$ pairs. In the proceedings, the preliminary results of measurements of partial branching fractions and the CKM matrix element $|V_{ub}|$ are presented.
We present the measurement of the first to fourth order moments of the four-momentum transfer squared, $q^{2}$, of inclusive $B \rightarrow X_{c} \ell ν$ decays using the full Belle data set consisting of $711~\rm fb^{-1}$ of integrated luminosity at the $Υ(4S)$ resonance for $\ell = e, μ$. The measured moments are crucial experimental inputs for a novel, data-driven approach to determine inclusive $|V_{cb}|$, which we implement in order to extract a preliminary value of $|V_{cb}| \times 10^{3} = 41.7 \pm 1.2$.
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…
The $b \rightarrow s γ$, $b \rightarrow d γ$ and $b \rightarrow s \ell^+ \ell^-$ processes are allowed at higher order via the electroweak loop or box diagrams in the Standard model. It is sensitive probe to search for new physics beyond the Standard model because new particles might enter in the loop. We present preliminary results of branching fraction of the $\bar{B} \rightarrow X_s γ$, $CP$ asymmetry in the $\bar{B} \rightarrow X_{s+d} γ$, and the forward-backward asymmetry in the $\bar{B} \rightarrow X_s \ell^+ \ell^-$. The results are based on a data sample containing $772 \times 10^6 B\…
This contribution illustrates a new search for the flavor-changing neutral-current decay ${B^+ \to K^+ ν\bar ν}$ performed by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. In this study, a sample corresponding to an integrated luminosity of $63\, \rm{fb}^{-1}$ collected at the $\rm Υ(4S)$ resonance and an additional sample of $9\, \rm{fb}^{-1}$ collected at an energy $60\, \rm MeV$ below the resonance are used. A novel technique, based on an inclusive tagging method and exploiting the topological features of the ${B^+ \to K^+ ν\bar ν}$ decay, is employe…
With the first data being recorded at Belle II, we are at the brink of a new era in quark flavour physics. The many exciting new opportunities for Belle~II include a full angular analysis of inclusive ${\bar B \to X_{s} \, \ell^+\ell^-}$ which has the potential to reveal new physics, in particular by its interplay with the exclusive $b \to s \ell^+\ell^-$ counterparts studied extensively at LHCb. In this paper, we present fully updated Standard Model predictions for all angular observables necessary for this endeavour. These predictions are tailored to Belle II and include an elaborate study o…
The Belle experiment at the KEKB asymmetric energy e+e- collider recorded large data sets of both, B and Bs decays. Semileptonic decays B(s) -> X l nu (l = electron or muon) constitute approximately one fifth of the total decay width of B(s) mesons and play an important role in the determination of the CKM matrix elements V_ub and V_cb. Recent results from Belle are presented, including the study of B- -> Ds(*) K l nu, the first measurements of semi-inclusive modes B -> D(*) X l nu and the measurement of the inclusive branching fraction Bf(Bs -> X l nu).
Radiative and electroweak penguin mediated decays of $B$ mesons are a great probe for physics beyond the Standard Model of particle physics. Furthermore, recently anomalies on exclusive $b \rightarrow s \ell^{+} \ell^{-}$ processes, which may imply lepton flavor universality violation, have been observed. Belle II experiment sheds light on the anomalies with the measurement of an inclusive analysis in this mode. Thanks to smaller hadronic uncertainties compared with exclusive modes, complementary information can be provided. Belle II is also a unique experiment to search for processes involvin…
Search for the Theta(1540)+ pentaquark using kaon secondary interactions at Belle
利用Belle探测器材料中的K介子二次相互作用，我们寻找包含性和排他性的Theta（1540）+的产生。我们将90% C. L.的上限设定为2.5%。关于包括Theta（1540）+与Lambda（1520）在内的产生截面的比率。我们还寻找了Theta（1540）+作为电荷交换反应K+ n -> pKs的中间共振。在90% C. L.处，γ（Theta+）的上限<0.64MeV。m（Theta+）=1.539MeV。这些结果是从KEKB非对称能量e+e-对撞机上Belle探测器在Upperion（4S）共振附近收集的397/fb数据样本中获得的。
Studies of semileptonic $B_s$ decays by the Belle, Babar and D0 experiments are reported. In particular measurements of inclusive semileptonic $B_s$ decays by Belle and Babar and the exclusive excited charm mode $B_s \to D_{s1} μν$ from D0 are presented. An outlook on further semileptonic $B_s$ measurements with $Υ(5S)$ data at Belle and Belle II is also given.
We present recent results for radiative and electroweak penguin decays of $B$ me son at Belle. Measurements of differential branching fraction, isospin asymmetr y, $K^*$ polarization, and forward-backward asymmetry as functions of $q^2$ for $B \to K^{(*)}ll$ decays are reported. For the results of the radiative process, we report measurements of branching fractions for inclusive $B\to X_s γ$ and the exclusive $B\to K η' γ$ modes.
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 …
A mini-review of measurements of inclusive semileptonic $B \to X_c\ellν$ and radiative $B\to X_sγ$ decays is presented. The semileptonic $X_c$ mass moments are presented from Belle and BABAR. The inclusive $B\to X_sγ$ gamma branching fraction is presented from Belle as well as a preliminary measurement of the direct CP-asymmetry of $B \to X_{s+d}γ$ decays at BABAR. Fundamental Standard Model parameters and heavy quark parameters can be derived from the $X_c$ mass and lepton energy moments from $B \to X_c\ellν$ decays and from the photon energy moments from $B \to X_sγ$ decays. The values of th…
Charmless hadronic $B$ decays are a good testing ground for the Standard Model (SM) of Particle Physics. The dominant amplitudes are CKM suppressed tree diagrams and/or $ b\to s$ or $b\to d$ loop ("penguin") diagrams. Non-SM particle could appear in the loop, and hence these decays are sensitive to search for New Physics (NP). Some of the recent measurements of two-body charmless hadronic $B$ decays from Belle and their prospects at Belle II are discussed.
We report the recent results of charmed baryon decays, based on the data collected by the Belle experiment at the KEKB collider. This includes the observation of the doubly Cabibbo-suppressed decay $Λ_c^+\toπ^-K^+p$, search for the decay $Λ_c^+\toϕp π^0$, and the branching fraction measurement of $Λ_c^+\toπ^+K^-pπ^0$.
The Belle~II Collaboration presents four new analyses: The measurement of $V_{ub}$ from $B \to πe ν_e$ decays with a fit to the differential $q^2$ spectrum, the determination of $V_{cb}$ using a fit to the differential $w$ distribution from $B^0 \to D^{\ast -} \ell^+ ν_\ell$ decays, and the measurement of $q^2$ moments in inclusive $B \to X_c \ell ν_\ell$ decays. In all these analyses tag-side $B$ meson is reconstructed in a fully hadronic decay chain. The last result are branching fraction measurement of $B \to K^\ast \ell^+ \ell^-$ decays using an untagged approach.
We review recent experimental results on Bd and Bs mesons decays by the BaBar and Belle experiments. These include measurements of the color-suppressed decays B0bar to D(*)0h0, h0=pi0, eta, etaprime, omega, observation of the baryonic decay B0bar to Lambdac+ Lambdabar K-, measurements of the charmless decays B to eta h, h=K, pi, B to Kpi and observation of CP eigenstates in the Bs decays: B0s to J/psi f0(980), B0s to J/psi f0(1370) and B0s to J/psi eta. The theoretical implications of these results will be considered.
The semileptonic $B$ meson decays of the type $B \to X_u \ell ν$ are important for measuring the magnitude of the CKM matrix element $V_{ub}$. Recent measurements of inclusive $B \to X_u e ν_e$ and hadronically tagged $B^0 \to π^- \ell^+ ν$ from the Belle II experiment are presented. The results are obtained using the data collected at Belle II between March 2019 and March 2020, with a total integrated luminosity of 37.8 ${\rm fb}^{-1}$. These preliminary measurements are used to validate the detector and reconstruction software performance. The measured preliminary branching fraction of $B^0 …
We report results of a search for tau lepton decays strongly suppressed in the Standard Model based on the world-largest data sample accumulated with the Belle detector at the KEKB asymmetric-energy e+e- collider. The decays include: lepton flavor and lepton number violating tau decays into a lepton (e or mu) and two charged mesons (K or pi) as well as lepton and baryon number violating tau decays into a Lambda and a charged meson (K or pi). The sensitivity to the branching fractions is significantly improved compared to our previous results and reaches O(10^{-8}).
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 $1.8\times10^{-4}$.
