We find evidence for the semileptonic baryonic decay B-→pp¯ℓ-ν¯ℓ (ℓ=e, μ), based on a data sample of 772 million BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB ...asymmetric-energy electron-positron collider. A neural-network based hadronic B-meson tagging method is used in this study. The branching fraction of B-→pp¯ℓ-ν¯ℓ is measured to be (5.8+2.4-2.1(stat)±0.9(syst))×10-6 with a significance of 3.2σ, where lepton universality is assumed. We also estimate the corresponding upper limit: B(B-→pp¯ℓ-ν¯ℓ)<9.6×10-6 at the 90% confidence level. This measurement helps constrain the baryonic transition form factor in B decays
We extract a relatively precise value for the decay constant of the meson by measuring B(D+ --> mu+nu) = (4.40 +/-0.66(+0.09)(-0.12) x 10(-4) using 281 pb(-1) of data taken on phi(3770) the resonance ...with the CLEO-c detector. We find fD+ = (222.6 +/- 16.7(+2.8)(-3.4)) MeV, and compare with current theoretical calculations. We also set a 90% confidence upper limit on B(D+e+nu)< 2.4 x 10(-5) which constrains new physics models.
Using data collected at the psi(3770) resonance with the CLEO-c detector at the Cornell e+e- storage ring, we present searches for 25 charmless decay modes of the psi(3770), mostly multibody final ...states. No evidence for charmless decays is found.
Using the CLEO detector at the Cornell Electron Storage Ring, we have observed the Bs meson in e+e- annihilation at the Y(5S) resonance. We find 14 candidates consistent with Bs decays into final ...states with a J/psi or a Ds(*)- . The probability that we have observed a background fluctuation is less than 8 x 10(-10) . We have established that at the energy of the Y(5S) resonance Bs production proceeds predominantly through the creation of Bs*Bs* pairs. We find sigma(e+e- --> Bs*Bs*) = 0.11(-0.03))(+0.04)(stat) +/- 0.02(syst)nb , and set the following limits: sigma(e+e- --> BsBs)/ sigma(e+ e- --> Bs*Bs*) <0.16 and sigma(e+e- --> BsBs*) + sigma(e+e- --> Bs*Bs)/sigma(e+e- -->Bs*Bs*) < 0.16 (90% C.L.). The mass of the Bs* meson is measured to be M(Bs*) = 5.414+/- 0.001(stat) +/- 0.003(syst) GeV/c2 .
Phys. Rev. Lett. 128, 142005 (2022) The measurement of two-particle angular correlation functions in
high-multiplicity $e^+e^-$ collisions at $\sqrt{s}=10.52$ GeV is reported. In
this study, the ...$89.5~{\text{fb}}^{-1}$ of hadronic $e^+e^-$ annihilation data
collected by the Belle detector at KEKB are used. Two-particle angular
correlation functions are measured in the full relative azimuthal angle
($\Delta \phi$) and three units of pseudorapidity ($\Delta \eta$), defined by
either the electron beam axis or the event-shape thrust axis, and are studied
as a function of charged-particle multiplicity. The measurement in the thrust
axis analysis, with mostly outgoing quark pairs determining the reference axis,
is sensitive to the region of additional soft gluon emissions. No significant
anisotropic collective behavior is observed with either coordinate analyses.
Near-side jet correlations appear to be absent in the thrust axis analysis. The
measurements are compared to predictions from various event generators and are
expected to provide new constraints to the phenomenological models in the
low-energy regime.
The branching fractions of Ds meson decays serve to normalize many measurements of processes involving charm quarks. Using 586 pb^-1 of e+ e- collisions recorded at a center of mass energy of 4.17 ...GeV, we determine absolute branching fractions for 13 Ds decays in 16 reconstructed final states with a double tag technique. In particular we make a precise measurement of the branching fraction B(Ds -> K- K+ pi+) = (5.55 +- 0.14 +- 0.13)%, where the uncertainties are statistical and systematic respectively. We find a significantly reduced value of B(Ds -> pi+ pi0 eta') compared to the world average, and our results bring the inclusively and exclusively measured values of B(Ds -> eta' X)$ into agreement. We also search for CP-violating asymmetries in Ds decays and measure the cross-section of e+ e- -> Ds* Ds at Ecm = 4.17 GeV.
Using of data collected with the CLEO-c detector, we report on first observations and measurements of Cabibbo-suppressed decays of D mesons in the following six decay modes: pi+ pi- pi0 pi0, pi+ pi+ ...pi- pi- pi0, pi+ pi0 pi0, pi+ pi+ pi- pi0, eta pi0, and omega pi+ pi-. Improved branching fraction measurements in eight other multipion decay modes are also presented. The measured D --> pi pi rates allow us to extract the ratio of isospin amplitudes A(DeltaI = (3/2) / A(DeltaI = (1/2)) = 0.420 +/- 0.014(stat) +/- 0.016(syst) and the strong phase shift of delta1 = (86.4 +/- 2.8 +/- 3.3) degrees, which is quite large and now more precisely determined.
We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa
(CKM) matrix element $V_{cb}$ using $B\to D\ell\nu$ decays. The result is based
on $e^+e^-\to\Upsilon(4S)$ data recorded ...by the Belle II detector corresponding
to 189.2/fb of integrated luminosity. The semileptonic decays $B^0\to D^-(\to
K^+\pi^-\pi^-)\ell^+\nu_\ell$ and $B^+\to\bar D^0(\to K^+\pi^-)\ell^+\nu_\ell$
are reconstructed, where $\ell$ is either electron or a muon. The second $B$
meson in the $\Upsilon(4S)$ event is not explicitly reconstructed. Using the
diamond-frame method, we determine the $B$ meson four-momentum and thus the
hadronic recoil. We extract the partial decay rates as functions of $w$ and
perform a fit to the decay form-factor and the CKM parameter $|V_{cb}|$ using
the BGL parameterization of the form factor and lattice QCD input from the
FNAL/MILC and HPQCD collaborations. We obtain $\eta_{EW}|V_{cb}|=(38.53\pm
1.15)\times 10^{-3}$, where $\eta_{EW}$ is an electroweak correction, and the
error accounts for theoretical and experimental sources of uncertainty.
JHEP03(2022)090 We present the first measurement of the branching fraction of the singly
Cabibbo-suppressed (SCS) decay $\Lambda_c^+ \to p \eta'$ with $\eta' \to
\eta\pi^+\pi^-$, using a data sample ...corresponding to an integrated luminosity
of 981 $\rm fb^{-1}$, collected by the Belle detector at the KEKB
$e^{+}$$e^{-}$ asymmetric-energy collider. A significant $\Lambda_c^+$ signal
is observed for the first time with a signal significance of 5.4$\sigma$. The
relative branching fraction with respect to the normalization mode $\Lambda_c^+
\to pK^-\pi^+$ is measured to be
\begin{equation*}
\frac{{\cal B}(\Lambda_c^+ \to p \eta')}{{\cal B}(\Lambda_c^+ \to p
K^-\pi^+)} = (7.54 \pm 1.32 \pm 0.75) \times 10^{-3},
\end{equation*}
where the uncertainties are statistical and systematic, respectively. Using
the world-average value of ${\cal B}(\Lambda_c^+ \to p K^-\pi^+) =
(6.28\pm0.32)\times10^{-2}$, we obtain
\begin{equation*}
{\cal B}(\Lambda_c^+ \to p \eta') = (4.73 \pm 0.82 \pm 0.47 \pm 0.24)\times
10^{-4},
\end{equation*}
where the uncertainties are statistical, systematic, and from ${\cal
B}(\Lambda_c^+ \to pK^-\pi^+)$, respectively.
PDF
