Chinese Physics C 47, (2023) 043001 Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with
the BESIII detector at the Beijing Electron Positron Collider corresponding to
a ...total integrated luminosity of approximately 18.8 $\rm fb^{-1}$, the process
$e^+e^- \to p p \bar{p} \bar{n} \pi^{-} + c.c.$ is observed for the first time
with a statistical significance of $11.5\sigma$. The average Born cross
sections in the energy ranges of (4.160, 4.380) GeV, (4.400, 4.600) GeV and
(4.610, 4.700) GeV are measured to be $(21.5\pm5.7\pm1.2)$ fb,
$(46.3\pm10.6\pm2.5)$ fb and $(59.0\pm9.4\pm3.2)$ fb, respectively, where the
first uncertainties are statistical and the second are systematic. The line
shapes of the $\bar{p}\bar{n}$ and $pp\pi^-$ invariant mass spectra are
consistent with phase space distributions, indicating that no hexaquark or
di-baryon state is observed.
Based on $e^+e^-$ collision samples corresponding to an integrated luminosity
of 4.4 $\mbox{fb$^{-1}$}$ collected with the BESIII detector at center-of-mass
energies between $4.6\,\,\mathrm{GeV}$ and ...$4.7\,\,\mathrm{GeV}$, a partial
wave analysis of the charmed baryon hadronic decay
$\Lambda_c^+\to\Lambda\pi^+\pi^0$ is performed, and the decays
$\Lambda_c^+\to\Lambda\rho(770)^{+}$ and $\Lambda_c^+\to\Sigma(1385)\pi$ are
studied for the first time. Making use of the world-average branching fraction
$\mathcal{B}(\Lambda_c^+\to\Lambda\pi^+\pi^0)$, their branching fractions are
determined to be \begin{eqnarray*} \begin{aligned}
\mathcal{B}(\Lambda_c^+\to\Lambda\rho(770)^+)=&(4.06\pm0.30\pm0.35\pm0.23)\times10^{-2},\\
\mathcal{B}(\Lambda_c^+\to\Sigma(1385)^+\pi^0)=&(5.86\pm0.49\pm0.52\pm0.35)\times10^{-3},\\
\mathcal{B}(\Lambda_c^+\to\Sigma(1385)^0\pi^+)=&(6.47\pm0.59\pm0.66\pm0.38)\times10^{-3},\\
\end{aligned} \end{eqnarray*} where the first uncertainties are statistical,
the second are systematic, and the third are from the uncertainties of the
branching fractions $\mathcal{B}(\Lambda_c^+\to\Lambda\pi^+\pi^0)$ and
$\mathcal{B}(\Sigma(1385)\to\Lambda\pi)$. In addition, %according to amplitudes
determined from the partial wave analysis, the decay asymmetry parameters are
measured to be $\alpha_{\Lambda\rho(770)^+}=-0.763\pm0.053\pm0.045$,
$\alpha_{\Sigma(1385)^{+}\pi^0}=-0.917\pm0.069\pm0.056$, and
$\alpha_{\Sigma(1385)^{0}\pi^+}=-0.789\pm0.098\pm0.056$.
It has been reported that limb ischemic preconditioning (LIP) could induce brain ischemic tolerance. In the present study, we investigated the role of p38 MAPK in the induction of brain ischemic ...tolerance by observing expression of phosphorylated p38 (p-p38) MAPK in the hippocampus after LIP and the effect of p38 MAPK inhibitor SB 203580 on the protection of LIP against delayed neuronal death (DND) in the CA1 hippocampus induced normally by brain ischemic insult. The results of Flow cytometry and Western blotting showed that expression of p-p38 MAPK initially increased at 6 h after LIP compared with sham group in the CA1 hippocampus. The increases reached peak at 12 h and lasted to 24 h after LIP. Expression of p-p38 MAPK was also increased in the CA3/dentate gyrus (DG) regions after LIP, but the beginning and peaking times were 1 and 3 days after LIP, which were relatively later than those in the CA1. Histological evaluation showed that LIP protected the CA1 hippocampal pyramidal neurons against DND induced by global brain ischemic insult for 8 min, suggesting the occurrence of brain ischemic tolerance. Pretreatment with SB 203580 at 30 min before LIP effectively blocked the ischemic tolerance induced by LIP. Together, it could be concluded that activation of p38 MAPK played an important role in the brain ischemic tolerance induced by LIP, and that components of the p38 MAPK cascade might be targets to modify neuronal survival in ischemic tolerance.
Phys. Rev. D 106, 112009 (2022) Using a data set of electron-positron collisions corresponding to an
integrated luminosity of ${\rm 2.93~fb^{-1}}$ taken with the BESIII detector at
a center-of-mass ...energy of 3.773 GeV, a search for the baryon ($B$) and lepton
($L$) number violating decays $D^{\pm}\to n(\bar{n})e^{\pm}$ is performed. No
signal is observed and the upper limits on the branching fractions at the
$90\%$ confidence level are set to be $1.43\times10^{-5}$ for the decays
$D^{+(-)}\to \bar{n}(n)e^{+(-)}$ with $\Delta|B-L|=0$, and $2.91\times10^{-5}$
for the decays $D^{+(-)}\to n(\bar{n})e^{+(-)}$ with $\Delta|B-L|=2$ , where
$\Delta|B-L|$ denotes the change in the difference between baryon and lepton
numbers.
The charge-density-wave (CDW) mechanism of the 3D quantum Hall effect has been observed recently in ZrTe\(_5\) Tang et al., Nature 569, 537 (2019). Different from previous cases, the CDW forms on a ...one-dimensional (1D) band of Landau levels, which strongly depends on the magnetic field. However, its theory is still lacking. We develop a theory for the CDW mechanism of 3D quantum Hall effect. The theory can capture the main features in the experiments. We find a magnetic field induced second-order phase transition to the CDW phase. We find that electron-phonon interactions, rather than electron-electron interactions, dominate the order parameter. We extract the electron-phonon coupling constant from the non-Ohmic I-V relation. We point out a commensurate-incommensurate CDW crossover in the experiment. More importantly, our theory explores a rare case, in which a magnetic field can induce an order-parameter phase transition in one direction but a topological phase transition in other two directions, both depend on one magnetic field.
Using a 3.19 fb^{-1} data sample collected at an e^{+}e^{-} center-of-mass energy of E_{cm}=4.178 GeV with the BESIII detector, we measure the branching fraction of the leptonic decay ...D_{s}^{+}→μ^{+}ν_{μ} to be B_{D_{s}^{+}→μ^{+}ν_{μ}}=(5.49±0.16_{stat}±0.15_{syst})×10^{-3}. Combining our branching fraction with the masses of the D_{s}^{+} and μ^{+} and the lifetime of the D_{s}^{+}, we determine f_{D_{s}^{+}}|V_{cs}|=246.2±3.6_{stat}±3.5_{syst} MeV. Using the c→s quark mixing matrix element |V_{cs}| determined from a global standard model fit, we evaluate the D_{s}^{+} decay constant f_{D_{s}^{+}}=252.9±3.7_{stat}±3.6_{syst} MeV. Alternatively, using the value of f_{D_{s}^{+}} calculated by lattice quantum chromodynamics, we find |V_{cs}|=0.985±0.014_{stat}±0.014_{syst}. These values of B_{D_{s}^{+}→μ^{+}ν_{μ}}, f_{D_{s}^{+}}|V_{cs}|, f_{D_{s}^{+}} and |V_{cs}| are each the most precise results to date.
Phys. Rev. D 106, 112002 (2022) Using a data sample of $(448.1 \pm 2.9)\times10^6 ~\psi(3686)$ decays
collected at an $e^+ e^-$ center-of-mass energy of $3.686~\rm{GeV}$ by the
BESIII detector at ...BEPCII, we report an observation of the hindered
electromagnetic Dalitz decay $\psi(3686) \to e^+ e^- \eta_c$ with a
significance of $7.9\sigma$. The branching fraction is determined to be
$\mathcal{B} (\psi(3686) \to e^+ e^- \eta_c) = (3.77 \pm 0.40_{\rm stat.} \pm
0.18_{\rm syst.})\times 10^{-5}$, agreeing well with the prediction of the
vector meson dominance model. This is the first measurement of the
electromagnetic Dalitz transition between the $\psi(3686)$ and the $\eta_c$,
which provides new insight into the electromagnetic properties of this decay,
and offers new opportunities to measure the absolute branching fractions of
$\eta_c$ decays.
Using a data sample of e^{+}e^{-} collisions corresponding to an integrated luminosity of 567 pb^{-1} collected at a center-of-mass energy of sqrts=4.6 GeV with the BESIII detector, we measure the ...absolute branching fraction of the inclusive semileptonic Λ_{c}^{+} decay with a double-tag method. We obtain B(Λ_{c}^{+}→Xe^{+}ν_{e})=(3.95±0.34±0.09)%, where the first uncertainty is statistical and the second systematic. Using the known Λ_{c}^{+} lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons (D^{0} and D^{+}), we obtain the ratio of the inclusive semileptonic decay widths Γ(Λ_{c}^{+}→Xe^{+}ν_{e})/Γover ¯(D→Xe^{+}ν_{e})=1.26±0.12.
Phys. Rev. D 106, 092004 (2022) A measurement of the $C\!P$-even fraction of the decay
$D^{0}\to\pi^{+}\pi^{-}\pi^{+}\pi^{-}$ is performed with a quantum-correlated
$\psi(3770)\to D\bar{D}$ data ...sample collected by the BESIII experiment,
corresponding to an integrated luminosity of 2.93 $\textrm{fb}^{-1}$. Using a
combination of $C\!P$ eigenstates, $D \to \pi^+\pi^-\pi^0$ and $D \to
K_{S,L}^0\pi^{+}\pi^{-}$ as tagging modes, the $C\!P$-even fraction is measured
to be $F_{+}^{4\pi} = 0.735 \pm 0.015 \pm 0.005$, where the first uncertainty
is statistical and the second is systematic. This is the most precise
determination of this quantity to date. It provides valuable model-independent
input for the measurement of the CKM angle $\gamma$ with $B^\pm\to D K^\pm$
decays, and for time-dependent studies of $C\!P$ violation and mixing in the
$D^{0}$-$\bar{D}^{0}$ system.
Eur. Phys. J. C 82, 1009 (2022) The decay $D\to K^-\pi^+$ is studied in a sample of quantum-correlated
$D\bar{D}$ pairs, based on a data set corresponding to an integrated luminosity
of ...2.93\,fb$^{-1}$ collected at the $\psi(3770)$ resonance by the BESIII
experiment. The asymmetry between $C\!P$-odd and $C\!P$-even eigenstate decays
into $K^-\pi^+$ is determined to be ${\cal A}_{K\pi} = 0.132 \pm 0.011 \pm
0.007$, where the first uncertainty is statistical and the second is
systematic. This measurement is an update of an earlier study exploiting
additional tagging modes, including several decay modes involving a $K^0_L$
meson. The branching fractions of the $K^0_L$ modes are determined as input to
the analysis in a manner that is independent of any strong phase uncertainty.
Using the predominantly $C\!P$-even tag $D\to \pi^+\pi^-\pi^0$ and the ensemble
of $C\!P$-odd eigenstate tags, the observable ${\cal A}_{K\pi}^{\pi\pi\pi^0}$
is measured to be $0.130 \pm 0.012 \pm 0.008$. The two asymmetries are
sensitive to $r_D^{K\pi} \cos \delta_D^{K\pi}$, where $r_D^{K\pi}$ and
$\delta_D^{K\pi}$ are the ratio of amplitudes and phase difference,
respectively, between the doubly Cabibbo-suppressed and Cabibbo-favoured
decays. In addition, events containing $D \to K^-\pi^+$ tagged by $D \to
K^0_{S,L} \pi^+\pi^-$ are studied in bins of phase space of the three-body
decays. This analysis has sensitivity to both $r_D^{K\pi} \cos \delta_D^{K\pi}$
and $r_D^{K\pi} \sin \delta_D^{K\pi}$. A fit to ${\cal A}_{K\pi}$, ${\cal
A}_{K\pi}^{\pi\pi\pi^0}$ and the phase-space distribution of the $D \to
K^0_{S,L} \pi^+\pi^-$ tags yields $\delta_D^{K\pi}= \left( 187.6
{^{+8.9}_{-9.7}}{^{+5.4}_{-6.4}} \right)$ degrees, where external constraints
are applied for $r_D^{K\pi}$ and other relevant parameters. This is the most
precise measurement of $\delta_D^{K\pi}$ in quantum-correlated $D\bar{D}$
decays.
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