We measure the $B^0$ lifetime and flavor-oscillation frequency using $B^0\to
D^{(*)-}\pi^+$ decays collected by the Belle II experiment in asymmetric-energy
$e^+e^-$ collisions produced by the ...SuperKEKB collider operating at the
$\Upsilon(4S)$ resonance. We fit the decay-time distribution of signal decays,
where the initial flavor is determined by identifying the flavor of the other
$B$ meson in the event. The results, based on $33000$ signal decays
reconstructed in a data sample corresponding to ${190}\text{fb}^{-1}$, are
$\tau_{B^0} = {1.499}\pm{0.013}\pm{0.008}\;\text{ps}$, $\Delta m_d =
{0.516}\pm{0.008}\pm{0.005}\;\text{ps}^{-1}$, where the first uncertainties are
statistical and the second are systematic. These results are consistent with
the world-average values.
We report a measurement of the mixing-induced and direct $\textit{CP}$
violation parameters $S_{\text{CP}}$ and $A_{\text{CP}}$ from $B^0 \to J/\psi
K^0_S$ decays reconstructed by the Belle II ...experiment at the SuperKEKB
asymmetric-energy electron-positron collider. The data, collected at the
center-of-mass energy of the $\Upsilon(4S)$ resonance, correspond to
$190\text{fb}^{-1}$ of integrated luminosity. We measure ${S_{\text{CP}} =
0.720\pm0.062\pm0.016}$ and $A_{\text{CP}} = 0.094\pm0.044^{+0.042}_{-0.017}$,
where the first uncertainties are statistical and the second systematic. In the
Standard Model, $S_{\text{CP}}$ equals $\sin(2\phi_1)$ to a good approximation.
We present a technically simple approach for gene expression cytometry combining next-generation sequencing with stochastic barcoding of single cells. A combinatorial library of beads bearing cell- ...and molecular-barcoding capture probes is used to uniquely label transcripts and reconstruct the digital gene expression profile of thousands of individual cells in a single experiment without the need for robotics or automation. We applied the technology to dissect the human hematopoietic system and to characterize heterogeneous response to in vitro stimulation. High sensitivity is demonstrated by detection of low-abundance transcripts and rare cells. Under current implementation, the technique can analyze a few thousand cells simultaneously and can readily scale to 10,000s or 100,000s of cells.
Phys. Rev. Lett. 131, 051804 (2023) We present the first measurement of the ratio of branching fractions of
inclusive semileptonic $B$-meson decays, $R(X_{e/\mu}) = \mathcal{B}(B\to X \,
e \, \nu) / ...\mathcal{B}(B\to X \, \mu \, \nu)$, a precision test of
electron-muon universality, using data corresponding to $189\,\mathrm{fb}^{-1}$
from electron-positron collisions collected with the Belle II detector. In
events where the partner $B$ meson is fully reconstructed, we use fits to the
lepton momentum spectra above $1.3\,\mathrm{GeV}/c$ to obtain $R(X_{e/\mu}) =
1.007 \pm 0.009~(\mathrm{stat}) \pm 0.019~(\mathrm{syst})$, which is the most
precise lepton-universality test of its kind and agrees with the standard-model
expectation.
We present a measurement of the $B^{0} \rightarrow D^{*-} \ell^{+}
\nu_{\ell}$ ($\ell=e,\mu$) branching ratio and of the CKM parameter $|V_{cb}|$
using signal decays accompanied by a fully ...reconstructed $B$ meson. The Belle
II data set of electron-positron collisions at the $\Upsilon(4S)$ resonance,
corresponding to 189.3$\,$fb$^{-1}$ of integrated luminosity, is analyzed. With
the Caprini-Lellouch-Neubert form factor parameterization, the parameters
$\eta_{\rm EW} F(1) |V_{cb}|$ and $\rho^{2}$ are extracted, where $\eta_{\rm
EW}$ is an electroweak correction, $F(1)$ is a normalization factor and
$\rho^{2}$ is a form factor shape parameter. We reconstruct 516 signal decays
and thereby obtain $\mathcal{B} (B^{0} \rightarrow D^{*-} \ell^{+} \nu_{\ell} )
= \left(5.27 \pm 0.22~\rm{\left(stat\right)} \pm
0.38~\rm{\left(syst\right)}\right) \%$, $\eta_{EW} F(1) |V_{cb}| \times 10^{3}
= 34.6 \pm 1.8~\rm{\left(stat\right)} \pm 1.7~\rm{\left(syst\right)}$, and
$\rho^{2} = 0.94 \pm 0.18~\rm{\left(stat\right)} \pm
0.11~\rm{\left(syst\right)}$.
The relation between the intransitive syntactic structure & the transitive functional structure (eg, John ate) is specified by the lexical mapping rule (Bresnan, J., "A Realistic Transformational ...Grammar" in Linguistic Theory and Psychological Reality, Halle, M., Bresnan, J., & Miller, G. Eds, Cambridge, Mass: MIT Press, 1978). This leads to quantifying the structure with logical inference rules. Since these inference rules are lexically governed, they are called meaning postulates & apply to semantically interpreted sentences. In the above example, John ate includes the meaning postulate that something was eaten after the lexical mapping. The argument is summarized: "...the assumption that syntactically intransitive eat is functionally intransitive can be preserved if & only if the entailments of intransitive eat are specified by meaning postulates rather than lexical mapping rules; ..." This supports the practice of separating quantificational semantics from lexical semantics. It appears that logical syntax is a shallow level of linguistic representation. R. Minerd
Phys. Rev. Lett. 130, 181803 (2023) We search for lepton-flavor-violating $\tau^-\to e^-\alpha$ and
$\tau^-\to\mu^-\alpha$ decays, where $\alpha$ is an invisible spin-0 boson. The
search uses ...electron-positron collisions at $10.58$ GeV center-of-mass energy
with an integrated luminosity of $62.8$ fb$^{-1}$, produced by the SuperKEKB
collider and collected with the Belle II detector. We search for an excess in
the lepton-energy spectrum of the known $\tau^-\to e^-\bar\nu_e \nu_\tau$ and
$\tau^-\to \mu^-\bar\nu_\mu \nu_\tau$ decays. We report 95\% confidence-level
upper limits on the branching-fraction ratio ${\mathcal B}(\tau^-\to e^-
\alpha) / {\mathcal B}(\tau^- \to e^- \bar\nu_e \nu_\tau)$ in the range
$(1.1-9.7) \times 10^{-3}$ and on ${\mathcal B}(\tau^-\to \mu^- \alpha) /
{\mathcal B}(\tau^- \to \mu^- \bar\nu_\mu \nu_\tau)$ in the range $(0.7-12.2)
\times 10^{-3}$ for $\alpha$ masses between 0 and 1.6 GeV/c$^2$. These results
provide the most stringent bounds on invisible boson production from $\tau$
decays.
Phys. Rev. Lett. 130, 231801 (2023) The $L_{\mu}-L_{\tau}$ extension of the standard model predicts the existence
of a lepton-flavor-universality-violating $Z^{\prime}$ boson that couples only
to the ...heavier lepton families. We search for such a $Z^\prime$ through its
invisible decay in the process $e^+ e^- \to \mu^+ \mu^- Z^{\prime}$. We use a
sample of electron-positron collisions at a center-of-mass energy of 10.58GeV
collected by the Belle II experiment in 2019-2020, corresponding to an
integrated luminosity of 79.7fb$^{-1}$. We find no excess over the expected
standard-model background. We set 90$\%$-confidence-level upper limits on the
cross section for this process as well as on the coupling of the model, which
ranges from $3 \times 10^{-3}$ at low $Z^{\prime}$ masses to 1 at $Z^{\prime}$
masses of 8$GeV/c^{2}$.
We present results on the semileptonic decays $B^0 \to \rho^- \ell^+
\nu_\ell$ and $B^+ \to \rho^0 \ell^+ \nu_\ell$ in a sample corresponding to
189.9/fb of Belle II data at the SuperKEKB $e^- e^+$ ...collider. Signal decays
are identified using full reconstruction of the recoil $B$ meson in hadronic
final states. We determine the total branching fractions via fits to the
distributions of the square of the "missing" mass in the event and the dipion
mass in the signal candidate and find ${\mathcal{B}(B^0\to\rho^-\ell^+
\nu_\ell) = (4.12 \pm 0.64(\mathrm{stat}) \pm 1.16(\mathrm{syst})) \times
10^{-4}}$ and ${\mathcal{B}({B^+\to\rho^0\ell^+\nu_\ell}) = (1.77 \pm 0.23
(\mathrm{stat}) \pm 0.36 (\mathrm{syst})) \times 10^{-4}}$ where the dominant
systematic uncertainty comes from modeling the nonresonant $B\to
(\pi\pi)\ell^+\nu_\ell$ contribution.
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.
