搜索结果：Hu li za zhi The journal of nursing

The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^2$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV $γ$ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4% for two 0.511 MeV $γ$ at the detector centre and 2.9% for the 0.93 MeV quenched Po-214 alpha decays from natural radioactive sources. The energy nonlinearity is calibrated to better than 1%. Intrinsic contaminations of U-238 and Th-232 in the liquid

Using 44.55 fb$^{-1}$ of $e^+e^-$ collision data collected by the BESIII detector at the BEPCII collider, we report the first measurement of the Born cross sections for the $e^+e^- \to K^+Ξ^0\barΣ^-$ reaction at fifty-six center-of-mass energies between 3.51 and 4.95~GeV. A fit to the dressed cross sections reveals the first observation of the $ψ(3770) \to K^+Ξ^0\barΣ^-$ process, with a statistical significance of 6.0$σ$ including systematic uncertainties. This result represents the first observation of charmless three-body baryonic decay of a vector charmonium state above the open-charm threshold. No significant signals for other charmonium(-like) states i.e., $ψ(4040)$, $ψ(4160)$, $Y(4230)$, $Y(4360)$, $ψ(4415)$, $Y(4500)$, $Y(4660)$ or $Y(4710)$ are observed, and the upper limits for the product of the branching fraction and the electronic partial width at the 90% confidence level for each assumed charmonium(-like) state are provided. Additionally, the ratios of Born cross sections between this work and the previous measurements of $e^+e^- \to K^{0}_{S}\barΞ^{-}Σ^-$ and $K^-\barΞ^+\barΣ^0$ are provided, which can be used to validate theoretical predictions related to isospin sym

We report the first measurement of the semileptonic decay $D^+_s \rightarrow K^*(892)^0μ^+ν_μ$ and an improved measurement of the decay $D^+_s \rightarrow K^*(892)^0 e^+ν_{e}$ using a sample of $7.33~\mathrm{fb}^{-1}$ of $e^+e^-$ annihilation data collected at center-of-mass energies between 4.128 to 4.226~GeV with the BESIII detector at the BEPCII collider. We measure the branching fractions to be $\mathcal B({D^+_s\rightarrow K^*(892)^0 μ^+ν_μ})=(2.07\pm0.22_{\rm stat}\pm0.10_{\rm syst})\times10^{-3}$ and $\mathcal B({D^+_s\rightarrow K^*(892)^0 e^+ν_{e}})=(2.14\pm0.18_{\rm stat}\pm0.10_{\rm syst})\times10^{-3}$. Based on a simultaneous study of the dynamics in two semileptonic decays, the hadronic form factor parameters in the $D^+_s\rightarrow K^{*}(892)^0$ transition are determined to be $r_{V} = V(0)/A_1(0) = 1.63 \pm 0.14_{\rm stat} \pm 0.08_{\rm syst}$, $r_{2} = A_2(0)/A_1(0) = 0.60 \pm 0.13_{\rm stat} \pm 0.06_{\rm syst}$, and $A_1(0)=0.56 \pm 0.02_{\rm stat} \pm 0.01_{\rm syst}$, where $V(0)$ is the vector form factor and $A_{1,2}(0)$ are the axial-vector form factors evaluated at $q^2=0$. The precision of $r_V$ and $r_2$ is improved by twofold and $A_1(0)$ is measured fo

Based on (2712.4+-14.3)*10^{6} psi(3686) events collected with the BESIII detector, the decays Xi(1530)^{-} to Xi^{0} pi^{-} and Xi(1530)^{-} to Xi^{-} pi^{0} are investigated jointly via the process psi(3686) to anti-Xi^{+} Xi(1530)^{-} + c.c. Under the assumption of isospin symmetry, the two decay modes are treated as fully correlated, and we report the first measurement of their absolute branching fractions. The results are B(Xi(1530)^{-} to Xi^{0} pi^{-})=(61.4+-4.5+-4.6)% and B(Xi(1530)^{-} to Xi^{-} pi^{0}) =(29.7+-2.2+-2.2)%. The combined branching fraction of the two decays is B(Xi(1530)^{-} to (Xi pi)^{-})=(91.1+-6.7+-6.8)%, with uncertainties accounting for the correlations between the two modes. Here, the first uncertainties are statistical, while the second are systematic. Additionally, we update the branching fraction of the decay psi(3686) to anti-Xi^{+} Xi(1530)^{-} + c.c. The updated measurement is B(psi(3686) to anti-Xi^{+} Xi(1530)^{-} + c.c.)=(8.67+-0.52+-0.58+-0.57)*10^{-6}, where the first uncertainty is statistical, the second is systematic related to event selection and the fit model, and the third is associated with the interference effect.

We search for possible charmonium(-like) states decaying into the $p\bar{p}$ final state by studying the Born cross sections of the $e^+e^-\to p\bar{p}$ reaction, and we determine the proton electromagnetic form factors by analyzing the proton angular distribution. The measurement is performed using a sample of $e^+e^-$ collision data collected at 47 center-of-mass energies from 3.510 to 4.946 GeV, corresponding to an integrated luminosity of 26 fb$^{-1}$, recorded by the BESIII detector collected at the BEPCII collider. The decay $ψ(3770)\to p\bar{p}$ is observed with a significance of 6.6$σ$ including systematic uncertainties. Furthermore, a structure near 4.2 GeV is observed with significances of $4.6σ$ or $4.8σ$ for the $ψ(4160)$ or $Y(4230)$ hypotheses including systematic uncertainties, respectively; these interpretations cannot presently be distinguished. In addition, the moduli of the form factor ratios $|G_{E}/G_{M}|$ and of the magnetic form factors $|G_{M}|$ are extracted by analyzing the proton polar angle distribution with higher precision at large time-like squared momentum transfer. These results provide important experimental insights into both the decay mechanisms

An amplitude analysis of the singly Cabibbo-suppressed decay $D^0 \to K^+ K^- π^0 π^0$ is performed, for the first time, to determine the relative magnitudes and phases of different intermediate processes. The analysis uses $e^+e^-$ collision data collected with the BESIII detector at the center-of-mass energy 3.773~GeV corresponding to an integrated luminosity of 20.3 $\rm fb^{-1}$. The absolute branching fraction of $D^0 \to K^+ K^- π^0 π^0$ is measured to be \BF. The dominant intermediate process is $D^0 \to K^{*}(892)^+K^{*}(892)^-$, with a branching fraction of $(2.79 \pm 0.13_{\rm{stat.}} \pm 0.11_{\rm{syst.}}) \times 10^{-3}$. Amplitude analysis reveals that the $D^0 \to K^{*}(892)^+K^{*}(892)^-$ decay is S-wave dominant. The longitudinal polarization fraction of $D^0 \to K^{*}(892)^+ K^{*}(892)^-$ is measured to be $0.468\pm0.046_{\rm{stat.}}\pm0.011_{\rm{syst.}}$.

We report a measurement of the Born cross section and the effective form factor for the $e^+e^-\to p\bar{p}$ reaction at 47 center-of-mass energies between 3.510 and 4.946 GeV. The measurement is performed using the energy-scan technique and is based on data corresponding to an integrated luminosity of 26 fb\(^{-1}\) collected with the BESIII detector at the BEPCII collider. For the first time, the moduli of the electromagnetic form factor ratio $|G_{E}/G_{M}|$ and of the magnetic form factor $|G_{M}|$ are determined with high precision by analyzing the distribution of the polar angle of the proton at a large timelike momentum transfer. These results provide essential insights into the nature of charmonium(-like) states above the open-charm threshold and the dynamics underlying the proton electromagnetic form factors.

We report the first observation of the decay $D_s^+ \to π^+π^0π^0η$ in a data set corresponding to an integrated luminosity of 7.33 fb$^{-1}$, collected in $e^+e^-$ collisions by the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV. An unexpectedly large branching fraction $\mathcal{B}( D_s^+ \to a_0(980)^+ f_0(500), a_0(980)^+ \to π^+η, f_0(500)\to π^0π^0) = (0.98 \pm 0.16_{\rm{stat.}} \pm 0.22_{\rm{syst.}})\%$ is measured with a significance exceeding $10σ$, offering new constraints on the internal structure of light scalar mesons. The dominant intermediate process is $D_s^+ \to a_1(1260)^+η, a_1(1260)^+\to ρ(770)^+π^0$ with a branching fraction of $(1.77 \pm 0.21_{\rm stat.} \pm 0.12_{\rm syst.})\%$. The isospin symmetry has been validated to the decays of $a_1(1260)^+\to ρ(770)^0π^+$ and $a_1(1260)^+\to ρ(770)^+π^0$. Moreover, the measured $\mathcal{B}(D_s^+\to π^+π^0π^0η|_{\rm{non}-η^\prime})=(2.97 \pm 0.23_{\rm stat.} \pm 0.14_{\rm sys.})$ reduces the undetected $D_s^+ \to ηX$ decay branching fractions to (0.1 $\pm$ 3.1)\%.

Improved measurements of the coherence factors and strong-phase differences in $D\to K^-π^+π^+π^-$ and $D\to K^-π^+π^0$ decays are reported, using quantum-correlated $D\bar{D}$ pairs produced in $e^+e^-$ annihilation at a center-of-mass energy of $3.773\,\mathrm{GeV}$, where $D$ denotes a quantum superposition of the flavour-specific $D^{0}$ and $\bar{D}^{0}$ mesons. The analysis employs a dataset collected by the BESIII experiment, corresponding to an integrated luminosity of $7.93~\rm fb^{-1}$. The observables sensitive to the coherence factors and strong-phase differences are measured by reconstructing one $D$ meson in the signal mode and the other in a tag mode. These parameters provide essential inputs to the measurement of the angle $γ$ of the Cabibbo-Kobayashi-Maskawa Unitarity Triangle in the LHCb and Belle II experiments. The coherence factors are determined to be $R_{K3π}=0.51\pm0.04$ and $R_{Kππ^0}=0.75\pm0.03$, and the strong-phase differences are $δ_D^{K3π}=\left(182^{+14}_{-13}\right)^\circ$ and $δ_D^{Kππ^0}=\left(209^{+7}_{-8}\right)^\circ$, where the uncertainties include both statistical and systematic contributions. For $D\to K^-π^+π^+π^-$, the parameters have bee

We present the first amplitude analysis and branching fraction measurement of $D^{+} \rightarrow K_{S}^{0}K_{L}^{0}π^{+}$ decay. The analysis uses a dataset corresponding to an integrated luminosity of 20.3~$\rm fb^{-1}$, which was recorded at a center-of-mass energy 3.773~GeV by the BESIII detector. The measured branching fraction is $\mathcal{B}(D^{+} \rightarrow K_{S}^{0}K_{L}^{0}π^{+})=(5.780\pm0.085\pm 0.052)\times10^{-3}$, where the first uncertainty is statistical and the second is systematic. Using the known value of ${\cal B}(D^+ \to φπ^+,\,φ\to K^+K^-)$, we determine the relative branching fraction between $φ\to K_{S}^0K_{L}^0$ and $φ\to K^+K^-$ to be $\mathcal{B}(D^{+} \to φπ^{+}, φ\to K_{S}^0K_{L}^0)/\mathcal{B}(D^{+} \to φπ^{+}, φ\to K^+K^-)= 0.628\pm0.022\pm 0.015\pm0.017$, where the third uncertainty is related to $\mathcal{B}(D^{+} \to φπ^{+}, φ\to K^+K^-)$. This result is significantly lower than the previous world average and is consistent with the isospin expectation for the $φ$ meson's coupling to charged and neutral kaon pairs.

We report a study of the semileptonic decays $D^0 \rightarrow \bar{K}^0π^-\ell^+ν_{\ell}$ (where $\ell=e,~μ$) based on a sample of $20.3~\mathrm{fb}^{-1}$ of $e^+e^-$ annihilation data collected at a center-of-mass energy of 3.773~GeV with the BESIII detector at the BEPCII collider. Based on an investigation of the decay dynamics in $D^0 \rightarrow \bar{K}^0π^-\ell^+ν_{\ell}$ decays, a $\mathcal{D}-$wave component of $D^0\rightarrow K_2^*(1430)^-\ell^+ν_{\ell}$ is observed for the first time with a statistical significance of $8.0σ$, in addition to the dominant $K^*(892)^-$ and $\mathcal{S}-$wave components. The $\mathcal{D}-$wave component is determined to account for $(0.092 \pm 0.028_{\rm stat} \pm 0.018_{\rm syst})\%$ of the total decay rate. The branching fractions of the dominant $K^*(892)^-$ components are measured as $\mathcal{B}(D^0\rightarrow K^{*}(892)^-e^+ν_{e}) = (2.043 \pm 0.018_{\rm stat} \pm 0.012_{\rm syst})\%$ and $\mathcal{B}(D^0\rightarrow K^{*}(892)^-μ^+ν_μ) = (1.964 \pm 0.018_{\rm stat} \pm 0.012_{\rm syst})\%$, which are the most precise measurements to date and represent significant improvements over the previous world averages. The hadronic form-factor par

Using $(10\,087 \pm 44) \times 10^6$ $J/ψ$ events collected with the BESIII detector, we perform the first amplitude analysis of the process $J/ψ\toγηπ^0$. The decay is dominated by the intermediate processes $J/ψ\toπ^0 b_1(1235)^0 \toγηπ^0$, $J/ψ\toπ^{0}ρ(1450)^0 \toγηπ^0$ and $J/ψ\toηh_1(1170) \toγηπ^0$. Contributions from $J/ψ\toγa_0(980)^0\toγηπ^0$, $J/ψ\toγa_2(1320)^0\toγηπ^0$ and $J/ψ\toγa_2(1700)^0\toγηπ^0$ are observed with a statistical significance exceeding $5σ$, constituting the first observation of radiative transitions of $J/ψ$ to isospin-triplet scalar mesons. The total branching fraction of $J/ψ\toγηπ^0$ is measured to be $(25.7\pm0.3\pm1.5)\times 10^{-6}$, where the first uncertainty is statistical and the second systematic. This result is consistent with the previous measurement, with the precision improved by more than a factor of two.

Using the data sample of $2.7\times10^9$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, we present an observation of the $Ξ(1530)^0$ polarization in the decay $ψ(3686)\toΞ(1530)^0\barΞ(1530)^0$ with a significance larger than $20σ$ compared with all other tested hypotheses. The helicity amplitudes for the process $ψ(3686)\toΞ(1530)^0\barΞ(1530)^0$ and the moduli of form factors including electric charge, magnetic dipole, electric quadrupole, and magnetic octupole are measured for the first time by performing an angular distribution analysis. Additionally, the polarization correlations between $Ξ(1530)^0$ and $\barΞ(1530)^0$ are measured.

A measurement of the CKM angle $γ$ and related strong-phase parameters is performed using a novel, model-independent approach in ${B^{\pm}\rightarrow D(\rightarrow K^{0}_{\rm S} h^{\prime+}h^{\prime-}) h^{\pm}}$ decays, where $h^{(\prime)} \equiv π, K$. The analysis uses a joint data sample of electron-positron collisions collected by the BESIII experiment at the Beijing Electron-Positron Collider II during 2010--2011 and 2021--2022, corresponding to an integrated luminosity of 8 fb$^{-1}$, and proton-proton collisions collected by the LHCb experiment at the Large Hadron Collider during 2011--2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. The two datasets are analyzed simultaneously by applying per-event weights based on the amplitude variation over the $D$-decay phase space to enhance the sensitivity to $C\!P$-violating observables. The CKM angle $γ$ is determined to be $γ= (71.3\pm 5.0)^{\circ}$, which constitutes the most precise single measurement to date.

Using 20.3~fb$^{-1}$ of $e^+e^-$ annihilation data collected at a center-of-mass energy of 3.773~GeV with the BESIII detector, we report the first observation of the semileptonic decays \mbox{$D^0\to K^-ωe^+ν_e$} and \mbox{$D^+\to K_S^0ωe^+ν_e$} with significances of $8.0σ$ and $5.8σ$, respectively. Their decay branching fractions are measured to be ${\cal B}(D^0\to K^-ωe^+ν_e)=(9.4^{+2.0}_{-1.8}\pm 0.6)\times10^{-5}$ and ${\cal B}(D^+\to K_S^0ωe^+ν_e)=(8.0^{+2.4}_{-2.1}\pm 0.7)\times10^{-5}$. Combining with the latest measurements of $D^{0(+)}\to K^-π^+π^{-(0)} e^+ν_e$ and assuming $\bar{K}_1(1270)$ to be the sole mediating resonance in all processes, the branching ratios are determined to be $\frac{Γ(K_1(1270)^-\to K^-π^+π^-)}{Γ(K_1(1270)^-\to K^-ω)} = 3.4^{+0.8}_{-0.7} \pm 0.3$ and $\frac{Γ(\bar{K}_1(1270)^0\to K^-π^+π^0)}{Γ(\bar{K}_1(1270)^0\to \bar{K}^0ω)} = 7.9^{+2.4}_{-2.1} \pm 0.7$. The combined branching fraction is determined to be $\mathcal B(\bar{K}_1(1270)\to \bar{K}ω) = (8.4\pm 1.4 \pm 0.5)\%$, which is the most precise measurement from a collider experiment. Furthermore, %based on the $\bar{K}π^+π^-π^0$ invariant mass spectra, for the first time based on a single vec

Using $e^+e^-$ annihilation data collected at 26 center-of-mass energy points between 3000.00 and $3119.88~\text{MeV}$ with the BESIII detector, corresponding to a total integrated luminosity of about $440.7~\text{pb}^{-1}$, we study the cross section lineshape of $e^+e^-\to K_S^0 K^+π^-+c.c.$. The relative phases and magnitudes between $J/ψ$ strong and electromagnetic decay amplitudes are measured to be $(123.7\pm5.3)^\circ;4.31\pm0.22$ or $(-123.1\pm5.2)^\circ;4.38\pm0.22$, with corresponding branching fractions $\mathcal{B}(J/ψ\to K_S^0 K^+π^-+c.c.)=(5.17\pm0.20)$ or $(5.36\pm0.20)\times10^{-3}$. Based on a partial wave analysis, the cross sections of $e^+e^-\to\bar K^0 K^*(892)^0+c.c.$ and $e^+e^-\to K^+ K^*(892)^-+c.c.$ are obtained. For these subprocesses, the relative phases and magnitudes are determined as $(155.2\pm15.5)^{\circ};3.67\pm0.27$ or $(-154.1\pm15.5)^{\circ};3.71\pm0.25$ and $(180.1\pm31.8)^{\circ};25.06\pm2.51$, respectively. The large relative phases deviate from the orthogonality relation expected from experiment and from the assumption of purely real amplitudes by more than $3σ$. The measured branching fractions $\mathcal{B}(J/ψ\to\bar K^0 K^*(892)^0)+c.c.=(

Using 20.3 fb$^{-1}$ of $e^+e^-$ collision data taken at the center-of-mass energy of $\sqrt{s}=3.773$ GeV, we report the first experimental constraint on the scalar current in the $D^{0(+)}\to \bar K\ell^+ν_{\ell}$ transitions, based on a simultaneous fit to the first measured forward-backward asymmetries and precisely determined partial decay rates. The parameters of the scalar current are determined to be ${\rm Re}(c_S^μ)=0.017\pm0.008_{\rm stat}\pm0.006_{\rm syst}$ and ${\rm Im}(c_S^μ)=\pm(0.077\pm0.011_{\rm stat}\pm0.009_{\rm syst})$, which deviates from the SM by a significance of $2.3σ$. The branching fractions of $D^{0(+)}\to \bar K\ell^+ν_\ell$, the hadronic form factor $f_+(0)$, and the modulus of the $c\to s$ CKM matrix element $|V_{cs}|$ are also determined with improved precision. In addition, lepton flavor universality is tested via the ratios of the decay rates between semi-muonic and semi-electronic decays in the full momentum transfer range and in subranges.

We present the first amplitude analysis of the hadronic decay $D^+\toπ^+π^0π^0$, using $e^{+}e^{-}$ collision data collected with the BESIII detector at a center-of-mass energy of 3.773~GeV, corresponding to an integrated luminosity of 20.3~fb$^{-1}$. The fit fractions of the intermediate processes are measured, in which the $D^+ \to ρ(770)^+π^0$ component is found to be dominant with a branching fraction of $(3.08\kern0.15em\pm\kern0.15em0.10_{\rm stat.}\pm0.05_{\rm syst.})\times10^{-3}$. Based on the amplitude analysis, the branching fraction of $D^+ \to π^+π^0π^0$ is measured to be $(4.84\kern0.1em\pm\kern0.1em0.05_{\rm stat.}\kern0.1em\pm\kern0.1em0.05_{\rm syst.})\times10^{-3}$. In addition, the CP asymmetries, both for specific amplitudes and integrated over the entire phase space, are measured.

Neutrino oscillations, a quantum effect manifesting at macroscopic scales, are governed by lepton flavor mixing angles and neutrino mass-squared differences that are fundamental parameters of particle physics, representing phenomena beyond the Standard Model. Precision measurements of these parameters are essential for testing the completeness of the three-flavor framework, determining the mass ordering of neutrinos, and probing possible new physics. The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid-scintillator detector located 52.5 km from multiple reactor cores, designed to resolve the interference pattern of reactor neutrinos with sub-percent precision. Here we report, using the first 59.1 days of data collected since detector completion in August 2025, the first simultaneous high-precision determination of two neutrino oscillation parameters, $\sin^2 θ_{12} = 0.3092\,\pm\,0.0087$ and $Δm^2_{21} = (7.50\,\pm\,0.12)\times10^{-5}\;{\rm eV}^2$ for the normal mass ordering scenario, improving the precision by a factor of 1.6 relative to the combination of all previous measurements. These results advance the basic understanding of neutrinos, validate the detec