We study the baryonic charmonium decays of B mesons B+-->etacK+ and B+-->J/psiK+, where the etac and J/psi subsequently decay into a ppover or LambdaLambdaover pair. We measure the J/psi-->ppover and ...LambdaLambdaover anisotropy parameters alphaB=-0.60+/-0.13+/-0.14 (ppover), -0.44+/-0.51+/-0.31 (LambdaLambdaover ) and compare to results from e;{+}e;{-}-->J/psi formation experiments. We also report the first observation of etac-->LambdaLambdaover. The measured branching fraction is B(etac-->LambdaLambdaover )=(0.87(+0.24)/(-0.21)(stat)(+0.09/-0.14) (syst)+/-0.27(PDG))x10-3. This study is based on a 357 fb-1 data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.
Phys. Rev. Lett. 130, 151903 (2023) Using the data sample of 980 fb$^{-1}$ collected with the Belle detector
operating at the KEKB asymmetric-energy $e^+e^-$ collider, we present the
results of an ...investigation of the $\Lambda\pi^+$ and $\Lambda\pi^-$ invariant
mass distributions looking for substructure in the decay
$\Lambda_c^+\rightarrow\Lambda\pi^+\pi^+\pi^-$. We find a significant signal in
each mass dis\ tribution. When interpreted as resonances, we find for the
$\Lambda\pi^+$ ($\Lambda\pi^-$) combination a mass of $1434.3 \pm 0.6
(\mathrm{stat}) \pm 0.9(\mathrm{syst})$ MeV/$c^2$ $1438.5 \pm 0.9
(\mathrm{stat}) \pm 2.5(\mathrm{syst})$ MeV/$c^2$, an intrinsic width of $11.5
\pm 2.8 (\mathrm{stat}) \pm 5.3(\mathrm{syst})$ MeV/$c^2$ $33.0 \pm 7.5
(\mathrm{stat}) \pm 23.6(\mathrm{syst})$ MeV/$c^2$ with a significance of
7.5$\sigma$ (6.2$\sigma$). As these two signals are very close to the
$\bar{K}N$ threshold, we also investigate the possibility of a $\bar{K}N$ cusp,
and find that \ we cannot discriminate between these two interpretations due to
the limited size of the data sample.
Phys. Rev. D 107, 092003 (2023) We report measurements of the ratios of branching fractions for $B \to
\bar{D}^{(*)}\pi\ell^+\nu_\ell$ and $B \to
\bar{D}^{(*)}\pi^+\pi^-\ell^+\nu_\ell$ relative to $B ...\to
\bar{D}^*\ell^+\nu_\ell$ decays with $\ell = e, \mu$. These results are
obtained from a data sample that contains $772 \times 10^6 B\bar{B}$ pairs
collected near the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB
asymmetric energy $e^+e^-$ collider. Fully reconstructing both $B$ mesons in
the event, we obtain \begin{align*} \frac{B(B^0 \to
\bar{D}^0\pi^-\ell^+\nu_\ell)}{B(B^0 \to D^{*-}\ell^+\nu_\ell)} &=
(7.24\pm0.36\pm0.12)\%\ ,\\ \frac{B(B^+ \to D^-\pi^+\ell^+\nu_\ell)}{B(B^+ \to
\bar{D}^{*0}\ell^+\nu_\ell)} &= (6.78\pm0.24\pm0.15)\%\ ,\\ \frac{B(B^0 \to
\bar{D}^{*0}\pi^-\ell^+\nu_\ell)}{B(B^0 \to D^{*-}\ell^+\nu_\ell)} &=
(11.10\pm0.48\pm0.20)\%\ ,\\ \frac{B(B^+ \to D^{*-}\pi^+\ell^+\nu_\ell)}{B(B^+
\to \bar{D}^{*0}\ell^+\nu_\ell)} &= (9.50\pm0.33\pm0.27)\%\ ,\\ \frac{B(B^0 \to
D^-\pi^+\pi^-\ell^+\nu_\ell)}{B(B^0 \to D^{*-}\ell^+\nu_\ell)} &=
(2.91\pm0.37\pm0.25)\%\ ,\\ \frac{B(B^+ \to
\bar{D}^0\pi^+\pi^-\ell^+\nu_\ell)}{B(B^+ \to \bar{D}^{*0}\ell^+\nu_\ell)} &=
(3.10\pm0.26\pm0.21)\%\ ,\\ \frac{B(B^0 \to
D^{*-}\pi^+\pi^-\ell^+\nu_\ell)}{B(B^0 \to D^{*-}\ell^+\nu_\ell)} &=
(1.03\pm0.43\pm0.18)\%\ ,\\ \frac{B(B^+ \to
\bar{D}^{*0}\pi^+\pi^-\ell^+\nu_\ell)}{B(B^+ \to \bar{D}^{*0}\ell^+\nu_\ell)}
&= (1.25\pm0.27\pm0.15)\%\ , \end{align*} where the uncertainties are
statistical and systematic, respectively. The invariant mass spectra of the
$D\pi$, $D^*\pi$, and $D\pi\pi$ systems are studied. Branching fraction
products are extracted, among them the first observations of $B(B^0 \to
D_1^-\ell^+\nu_\ell) \times B(D_1^- \to D^-\pi^+\pi^-) =
(0.102\pm0.013\pm0.009)\%$ and $B(B^+ \to \bar{D}_1^0\ell^+\nu_\ell) \times
B(\bar{D}_1^0 \to \bar{D}^0\pi^+\pi^-) = (0.105\pm0.011\pm0.008)\%$.
We present a measurement of the angle phi1 of the Cabibbo-Kobayashi-Maskawa unitarity triangle using a time-dependent Dalitz analysis of D-->KS(0)pi + pi- decays produced in neutral B meson decay to ...a neutral D meson and a light meson (B0-->D*h0). The method allows a direct extraction of 2phi1 and, therefore, helps to resolve the ambiguity between 2phi1 and pi-2phi1 in the measurement of sin2phi1. We obtain sin2phi1= 0.78 +/- 0.44 +/- 0.22 and cos2varphi1 = 1.87(-0.53-0.32)(+0.40 + 0.22). The sign of cos2phi1 is determined to be positive at 98.3% C.L.
Phys. Rev. D 107, 032004 (2023) We present a study of a singly Cabibbo-suppressed decay
$\Lambda_c^+\to{}pK_S^0K_S^0$ and a Cabibbo-favored decay
$\Lambda_c^+\to{}pK_S^0\eta$ based on 980 $\rm ...fb^{-1}$ of data collected by
the Belle detector, operating at the KEKB energy-asymmetric $e^+e^-$ collider.
We measure their branching fractions relative to $\Lambda_c^+\to{}pK_S^0$:
$\mathcal{B}(\Lambda_c^+\to{}pK_S^0K_S^0)/\mathcal{B}(\Lambda_c^+\to{}pK_S^0)={(1.48
\pm 0.08 \pm 0.04)\times 10^{-2}}$ and
$\mathcal{B}(\Lambda_c^+\to{}pK_S^0\eta)/\mathcal{B}(\Lambda_c^+\to{}pK_S^0)={(2.73\pm
0.06\pm 0.13)\times 10^{-1}}$. Combining with the world average
$\mathcal{B}(\Lambda_c^+\to{}pK_S^0)$, we have the absolute branching
fractions: $\mathcal{B}(\Lambda_c^+\to{}pK_S^0K_S^0) = {(2.35\pm 0.12\pm 0.07
\pm 0.12 )\times 10^{-4}}$ and $\mathcal{B}(\Lambda_c^+\to{}pK_S^0\eta) =
{(4.35\pm 0.10\pm 0.20 \pm 0.22 )\times 10^{-3}}$. The first and second
uncertainties are statistical and systematic, respectively, while the third
ones arise from the uncertainty on $\mathcal{B}(\Lambda_c^+\to{}pK_S^0)$. The
mode $\Lambda_c^+\to{}pK_S^0K_S^0$ is observed for the first time and has a
statistical significance of $>\!10\sigma$. The branching fraction of
$\Lambda_c^+\to{}pK_S^0\eta$ has been measured with a threefold improvement in
precision over previous results and is found to be consistent with the world
average.
Using a data sample of 980 fb$^{-1}$ collected with the Belle detector at the
KEKB asymmetric-energy $e^+e^-$ collider, we study for the first time the
singly Cabibbo-suppressed decays ...$\Omega^0_c\to\Xi^{-}\pi^{+}$ and
$\Omega^-K^+$ and the doubly Cabibbo-suppressed decay $\Omega^0_c\to \Xi^-
K^{+}$. Evidence for an $\Omega^0_c$ signal in the $\Omega^0_c\to\Xi^-\pi^+$
mode is reported with a significance of $4.5\sigma$ including systematic
uncertainties. The ratio of branching fractions to the normalization mode
$\Omega_c^0\to \Omega^-\pi^+$ is measured to be $${\cal B}(\Omega_{c}^{0} \to
\Xi^{-} \pi ^{+} )/{\cal B}(\Omega_c^0\to \Omega^-\pi^+)=0.253\pm 0.053({\rm
stat.})\pm 0.030({\rm syst.}).$$ No significant signals of
$\Omega^0_c\to\Xi^-K^+$ and $\Omega^-K^+$ modes are found. The upper limits at
$90\%$ confidence level on ratios of branching fractions are determined to be
$${\cal B}(\Omega_{c}^{0} \to \Xi^{-} K ^{+})/{\cal B}(\Omega_c^0\to
\Omega^-\pi^+) < 0.070$$ and $${\cal B}(\Omega_{c}^{0} \to
\Omega^{-}K^{+})/{\cal B}(\Omega_c^0\to \Omega^-\pi^+) < 0.29.$$
The Silicon Vertex Detector (SVD), with its four double-sided silicon strip sensor layers, is one of the two vertex sub-detectors of Belle II operating at SuperKEKB collider (KEK, Japan). Since 2019 ...and the start of the data taking, the SVD has demonstrated a reliable and highly efficient operation, even running in an environment with harsh beam backgrounds that are induced by the world's highest instantaneous luminosity. In order to provide the best quality track reconstruction with an efficient pattern recognition and track fit, and to correctly propagate the uncertainty on the hit's position to the track parameters, it is crucial to precisely estimate the resolution of the cluster position measurement. Several methods for estimating the position resolution directly from the data will be discussed.
We report results on a Dalitz analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decay including searches for direct CP violation. We report the first observation of the decay B+/- --> ...f2(1270)K+/- with a statistical significance above 6sigma. We also observe first evidence for large direct CP violation in the B+/- --> rho(770)0K+/- channel. The results are obtained with a data sample that contains 386 10(6) BB pairs collected at the Y(4s) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
Phys. Rev. D 107, 032003 (2023) We report a study of $\Lambda_c^+ \to \Sigma^+ \pi^0$, $\Lambda_c^+ \to
\Sigma^+ \eta$, and $\Lambda_c^+ \to \Sigma^+ \eta'$ using the data sample
corresponding to an ...integrated luminosity of 980 $\rm fb^{-1}$ collected with
the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The
branching fractions relative to $\Lambda_c^+ \to \Sigma^+ \pi^0$ are measured
as: $\mathcal{B}_{\Lambda_c^+ \to \Sigma^+ \eta}/\mathcal{B}_{\Lambda_c^+ \to
\Sigma^+ \pi^0}=0.25 \pm 0.03 \pm 0.01$ and $\mathcal{B}_{\Lambda_c^+ \to
\Sigma^+ \eta'}/\mathcal{B}_{\Lambda_c^+ \to \Sigma^+ \pi^0}=0.33 \pm 0.06 \pm
0.02$. Using $\mathcal{B}_{\Lambda_c^+ \to \Sigma^+ \pi^0}=(1.25 \pm 0.10)\%$,
we obtain $\mathcal{B}_{\Lambda_c^+ \to \Sigma^+ \eta}=(3.14 \pm 0.35 \pm 0.11
\pm 0.25)\times10^{-3}$ and $\mathcal{B}_{\Lambda_c^+ \to \Sigma^+ \eta'}=(4.16
\pm 0.75 \pm 0.21 \pm 0.33)\times10^{-3}$. Here the uncertainties are
statistical, systematic, and from $\mathcal{B}_{\Lambda_c^+ \to \Sigma^+
\pi^0}$, respectively. The ratio of the branching fraction of $\Lambda_c^+ \to
\Sigma^+ \eta'$ with respect to that of $\Lambda_c^+ \to \Sigma^+ \eta$ is
measured to be $\mathcal{B}_{\Lambda_c^+ \to \Sigma^+
\eta'}/\mathcal{B}_{\Lambda_c^+ \to \Sigma^+ \eta}=1.34 \pm 0.28 \pm 0.06$. We
update the asymmetry parameter of $\Lambda_c^+ \to \Sigma^+ \pi^0$,
$\alpha_{\Sigma^+ \pi^0} = -0.48 \pm 0.02 \pm 0.02$, with a considerably
improved precision. The asymmetry parameters of $\Lambda_c^+ \to \Sigma^+ \eta$
and $\Lambda_c^+ \to \Sigma^+ \eta'$ are measured to be $\alpha_{\Sigma^+ \eta}
= -0.99 \pm 0.03 \pm 0.05$ and $\alpha_{\Sigma^+ \eta'} = -0.46 \pm 0.06 \pm
0.03$ for the first time.
PDF