Search for Rare Decays of D_{s}

Using 7.33 fb^{-1} of e^{+}e^{-} collision data collected by the BESIII detector at center-of-mass energies in the range of sqrt[s]=4.128-4.226 GeV, we search for the rare decays D_{s}^{+}→h^{+}(h^{0})e^{+}e^{-}, where h represents a kaon or pion. By requiring the e^{+}e^{-} invariant mass to be consistent with a ϕ(1020), 0.98

Measurement of Electron Antineutrino Oscillation Amplitude and Frequency via Neutron Capture on Hydrogen at Daya Bay.

This Letter reports the first measurement of the oscillation amplitude and frequency of reactor antineutrinos at Daya Bay via neutron capture on hydrogen using 1958 days of data. With over 3.6 million signal candidates, an optimized candidate selection, improved treatment of backgrounds and efficiencies, refined energy calibration, and an energy response model for the capture-on-hydrogen sensitive region, the relative ν[over ¯]_{e} rates and energy spectra variation among the near and far detectors gives sin^{2}2θ_{13}=0.0759_{-0.0049}^{+0.0050} and Δm_{32}^{2}=(2.72_{-0.15}^{+0.14})×10^{-3} eV^{2} assuming the normal neutrino mass ordering, and Δm_{32}^{2}=(-2.83_{-0.14}^{+0.15})×10^{-3} eV^{2} for the inverted neutrino mass ordering. This estimate of sin^{2}2θ_{13} is consistent with and essentially independent from the one obtained using the capture-on-gadolinium sample at Daya Bay. The combination of these two results yields sin^{2}2θ_{13}=0.0833±0.0022, which represents an 8% relative improvement in precision regarding the Daya Bay full 3158-day capture-on-gadolinium result.

Precise Measurement of Born Cross Sections for e

Using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies ranging from 3.80 to 4.95 GeV, corresponding to an integrated luminosity of 20 fb^{-1}, a measurement of Born cross sections for the e^{+}e^{-}→D^{0}D[over ¯]^{0} and D^{+}D^{-} processes is presented with unprecedented precision. Many clear peaks in the line shape of e^{+}e^{-}→D^{0}D[over ¯]^{0} and D^{+}D^{-} around the mass range of G(3900), ψ(4040), ψ(4160), Y(4260), and ψ(4415), etc., are foreseen. These results offer crucial experimental insights into the nature of hadron production in the open-charm region.

Strong and Weak CP Tests in Sequential Decays of Polarized Σ

The J/ψ, ψ(3686)→Σ^{0}Σ[over ¯]^{0} processes and subsequent decays are studied using the world's largest J/ψ and ψ(3686) data samples collected with the BESIII detector. The parity-violating decay parameters of the decays Σ^{0}→Λγ and Σ[over ¯]^{0}→Λ[over ¯]γ, α_{Σ^{0}}=-0.0017±0.0021±0.0018 and α[over ¯]_{Σ^{0}}=0.0021±0.0020±0.0022, are measured for the first time. The strong CP symmetry is tested in the decays of the Σ^{0} hyperons for the first time by measuring the asymmetry A_{CP}^{Σ}=α_{Σ^{0}}+α[over ¯]_{Σ^{0}}=(0.4±2.9±1.3)×10^{-3}. The weak CP test is performed in the subsequent decays of their daughter particles Λ and Λ[over ¯]. Also for the first time, the transverse polarizations of the Σ^{0} hyperons in J/ψ and ψ(3686) decays are observed with opposite directions, and the ratios between the S-wave and D-wave contributions of the J/ψ, ψ(3686)→Σ^{0}Σ[over ¯]^{0} decays are obtained. These results are crucial to understand the decay dynamics of the charmonium states and the production mechanism of the Σ^{0}-Σ[over ¯]^{0} pairs.

Search for a Sub-eV Sterile Neutrino Using Daya Bay's Full Dataset.

This Letter presents results of a search for the mixing of a sub-eV sterile neutrino with three active neutrinos based on the full data sample of the Daya Bay Reactor Neutrino Experiment, collected during 3158 days of detector operation, which contains 5.55×10^{6} reactor ν[over ¯]_{e} candidates identified as inverse beta-decay interactions followed by neutron capture on gadolinium. The analysis benefits from a doubling of the statistics of our previous result and from improvements of several important systematic uncertainties. No significant oscillation due to mixing of a sub-eV sterile neutrino with active neutrinos was found. Exclusion limits are set by both Feldman-Cousins and CLs methods. Light sterile neutrino mixing with sin^{2}2θ_{14}≳0.01 can be excluded at 95% confidence level in the region of 0.01 eV^{2}≲|Δm_{41}^{2}|≲0.1 eV^{2}. This result represents the world-leading constraints in the region of 2×10^{-4} eV^{2}≲|Δm_{41}^{2}|≲0.2 eV^{2}.

Developmental Changes in Pharyngeal Airway in the Male Population From Adolescence to Adulthood.

AIM: During adolescence, there is a significant surge in height and total body mass of males. Consequently, they simultaneously experience enhancements in their circulatory and respiratory systems, which adapt to these physiological transformations. The purpose of present study was to investigate the developmental changes in male pharyngeal airway from adolescence to adulthood. METHODS: Lateral cephalograms of 192 males were obtained and divided into 5 groups: early adolescence (age 10-13 years), middle adolescence (age 14-17 years), late adolescence (age 18-21 years), early adulthood (age 22-30 years), and middle adulthood (ages 31-50 years). The dimensions of pharyngeal airway spaces and the related anatomical structures were investigated. The one-way analysis of variance and Pearson correlation analysis were employed for statistical analysis. CONCLUSION: During middle adolescence, the pharyngeal airway seems to be nearly completed in males. A significant negative correlation was found between the ANB angle and SPS, TPS, and EPS values.

Properties of Cosmic Deuterons Measured by the Alpha Magnetic Spectrometer.

Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of the deuteron (D) flux are presented. The measurements are based on 21×10^{6} D nuclei in the rigidity range from 1.9 to 21 GV collected from May 2011 to April 2021. We observe that over the entire rigidity range the D flux exhibits nearly identical time variations with the p, ^{3}He, and ^{4}He fluxes. Above 4.5 GV, the D/^{4}He flux ratio is time independent and its rigidity dependence is well described by a single power law ∝R^{Δ} with Δ_{D/^{4}He}=-0.108±0.005. This is in contrast with the ^{3}He/^{4}He flux ratio for which we find Δ_{^{3}He/^{4}He}=-0.289±0.003. Above ∼13 GV we find a nearly identical rigidity dependence of the D and p fluxes with a D/p flux ratio of 0.027±0.001. These unexpected observations indicate that cosmic deuterons have a sizable primarylike component. With a method independent of cosmic ray propagation, we obtain the primary component of the D flux equal to 9.4±0.5% of the ^{4}He flux and the secondary component of the D flux equal to 58±5% of the ^{3}He flux.

Measurements of Normalized Differential Cross Sections of Inclusive η Production in e

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e^{+}e^{-}→η+X, normalized by the total cross section of e^{+}e^{-}→hadrons, is measured at eight center-of-mass energy points from 2.0000 to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy compared to the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well.

Linearization of wavelength sweeping lasers for the construction of 4-D FMCW LiDAR images of slow-moving objects using baseband beat note signals.

A FMCW LiDAR system of both the distributed feedback laser and external cavity laser is established in baseband beat notes, rather than up-conversion to an intermediate frequency to exclude flicker noise. Meanwhile, utilizing fast-scanning MEMS mirrors, high-quality real-time (1 fps) 4-D images of the slow-moving object (10 mm/s) can be directly constructed at the baseband with a central frequency as low as 100 kHz and a small Doppler shift. The proposed LiDAR architecture based on such a low-frequency baseband significantly improves the optical power budget on the transmitter side and eliminates the costly high-speed sampling circuits on the receiver side.

First Study of Antihyperon-Nucleon Scattering Λ[over ¯]p→Λ[over ¯]p and Measurement of Λp→Λp Cross Section.

Using (10.087±0.044)×10^{9} J/ψ events collected with the BESIII detector at the BEPCII storage ring, the processes Λp→Λp and Λ[over ¯]p→Λ[over ¯]p are studied, where the Λ/Λ[over ¯] baryons are produced in the process J/ψ→ΛΛ[over ¯] and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in -0.9≤cosθ_{Λ/Λ[over ¯]}≤0.9 are measured to be σ(Λp→Λp)=(12.2±1.6_{stat}±1.1_{syst}) and σ(Λ[over ¯]p→Λ[over ¯]p)=(17.5±2.1_{stat}±1.6_{syst}) mb at the Λ/Λ[over ¯] momentum of 1.074 GeV/c within a range of ±0.017 GeV/c, where the θ_{Λ/Λ[over ¯]} are the scattering angles of the Λ/Λ[over ¯] in the Λp/Λ[over ¯]p rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for Λp→Λp, and a strong forward peak for Λ[over ¯]p→Λ[over ¯]p. We present an approach to extract the total elastic cross sections by extrapolation. The study of Λ[over ¯]p→Λ[over ¯]p represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction.

[Analysis and prediction of epidemiological characteristics of tuberculosis deaths among Chinese residents from 2006 to 2021].

Objective: The epidemiological characteristics of tuberculosis deaths among Chinese residents from 2006 to 2021 were analyzed, and the tuberculosis mortality rate from 2022 to 2027 was predicted to provide a reference for tuberculosis prevention and control in China. Methods: The data set of tuberculosis deaths from 2006 to 2021 was published regularly by the China CDC, and the crude mortality rate (CMR) and age-standardized mortality rates (ASMR) were calculated according to the population structure of China in 2000. The distribution characteristics of age, sex, region, and time of tuberculosis deaths were analyzed, the Joinpoint regression analysis model was used to analyze the changing trend, and the grey model was applied to predict CMR and ASMR from 2022 to 2027. Results: From 2006 to 2021, the CMR and ASMR of tuberculosis showed a downward trend among males and females, urban and rural areas, and all age groups, in a word, all the Chinese residents. Except for the age group ≥85 years old, the mortality trend was insignificant. In the eastern, central, or western regions. CMR and ASMR were significantly higher in males than in females.CMR and ASMR were significantly lower in urban areas than in rural areas. In general, active tuberculosis patients present a higher mortality rate. The CMR and ASMR in the western region were higher than those in the eastern and central regions and lower in the eastern region than in the central region, but the differences were less obvious. The ASMR of the eastern cities was lower than that of the central and western regions, and the ASMR of the central cities was higher than that of the western region from 2006 to 2009 and 2012 and lower than that of the western region in other years. The ASMR in the western countryside was higher than that in the eastern and central regions and lower in the eastern part than in the central region, but the difference was not obvious. The grey model prediction results show that the CMR (/100 000) of Chinese residents from 2022 to 2027 is 1.585, 1.471, 1.360, 1.250, 1.143, and 1.038, and the ASMR (/100 000) is 0.779, 0.653, 0.531, 0.411, 0.295 and 0.181, respectively. Conclusions: The CMR and ASMR of tuberculosis will continue to decline, and extraordinary achievements have been made in tuberculosis prevention and control in Chinese residents from 2006 to 2021 and, presumably, from 2022 to 2027. However, tuberculosis screening and treatment programs in the western region, men, the elderly population, and rural areas should be further strengthened, and targeted prevention and control measures should be formulated to reduce mortality.

Observation of Structures in the Processes e

We present measurements of the Born cross sections for the processes e^{+}e^{-}→ωχ_{c1} and ωχ_{c2} at center-of-mass energies sqrt[s] from 4.308 to 4.951 GeV. The measurements are performed with data samples corresponding to an integrated luminosity of 11.0 fb^{-1} collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring. Assuming the e^{+}e^{-}→ωχ_{c2} signals come from a single resonance, the mass and width are determined to be M=(4413.6±9.0±0.8) MeV/c^{2} and Γ=(110.5±15.0±2.9) MeV, respectively, which is consistent with the parameters of the well-established resonance ψ(4415). In addition, we also use one single resonance to describe the e^{+}e^{-}→ωχ_{c1} line shape and determine the mass and width to be M=(4544.2±18.7±1.7) MeV/c^{2} and Γ=(116.1±33.5±1.7) MeV, respectively. The structure of this line shape, observed for the first time, requires further understanding.

First Observation of a Three-Resonance Structure in e

We report the measurement of the inclusive cross sections for e^{+}e^{-}→nOCH (where nOCH denotes non-open charm hadrons) with improved precision at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV. We observe three resonances: R(3760), R(3780), and R(3810) with significances of 8.1σ, 13.7σ, and 8.8σ, respectively. The R(3810) state is observed for the first time, while the R(3760) and R(3780) states are observed for the first time in the nOCH cross sections. Two sets of resonance parameters describe the energy-dependent line shape of the cross sections well. In set I [set II], the R(3810) state has mass (3805.7±1.1±2.7) [(3805.7±1.1±2.7)] MeV/c^{2}, total width (11.6±2.9±1.9) [(11.5±2.8±1.9)] MeV, and an electronic width multiplied by the nOCH decay branching fraction of (10.9±3.8±2.5) [(11.0±3.4±2.5)] eV. In addition, we measure the branching fractions B[R(3760)→nOCH]=(25.2±16.1±30.4)%[(6.4±4.8±7.7)%] and B[R(3780)→nOCH]=(12.3±6.6±8.3)%[(10.4±4.8±7.0)%] for the first time. The R(3760) state can be interpreted as an open-charm (OC) molecular state, but containing a simple four-quark state component. The R(3810) state can be interpreted as a hadrocharmonium state.

Determination of Spin-Parity Quantum Numbers of X(2370) as 0

Based on (10087±44)×10^{6} J/ψ events collected with the BESIII detector, a partial wave analysis of the decay J/ψ→γK_{S}^{0}K_{S}^{0}η^{'} is performed. The mass and width of the X(2370) are measured to be 2395±11(stat)_{-94}^{+26}(syst) MeV/c^{2} and 188_{-17}^{+18}(stat)_{-33}^{+124}(syst) MeV, respectively. The corresponding product branching fraction is B[J/ψ→γX(2370)]×B[X(2370)→f_{0}(980)η^{'}]×B[f_{0}(980)→K_{S}^{0}K_{S}^{0}]=(1.31±0.22(stat)_{-0.84}^{+2.85}(syst))×10^{-5}. The statistical significance of the X(2370) is greater than 11.7σ and the spin parity is determined to be 0^{-+} for the first time. The measured mass and spin parity of the X(2370) are consistent with the predictions of the lightest pseudoscalar glueball.

Coupled-Channel Analysis of the χ_{c1}(3872) Line Shape with BESIII Data.

We perform a study of the χ_{c1}(3872) line shape using the data samples of e^{+}e^{-}→γχ_{c1}(3872), χ_{c1}(3872)→D^{0}D[over ¯]^{0}π^{0}, and π^{+}π^{-}J/ψ collected with the BESIII detector. The effects of the coupled channels and the off-shell D^{*0} are included in the parametrization of the line shape. The line shape mass parameter is obtained to be M_{X}=(3871.63±0.13_{-0.05}^{+0.06}) MeV. Two poles are found on the first and second Riemann sheets corresponding to the D^{*0}D[over ¯]^{0} branch cut. The pole location on the first sheet is much closer to the D^{*0}D[over ¯]^{0} threshold than the other, and is determined to be 7.04±0.15_{-0.08}^{+0.07} MeV above the D^{0}D[over ¯]^{0}π^{0} threshold with an imaginary part -0.19±0.08_{-0.19}^{+0.14} MeV.

Observation of the Anomalous Shape of X(1840) in J/ψ→γ3(π

Using a sample of (10087±44)×10^{6} J/ψ events, which is about 45 times larger than that was previously analyzed, a further investigation on the J/ψ→γ3(π^{+}π^{-}) decay is performed. A significant distortion at 1.84 GeV/c^{2} in the line shape of the 3(π^{+}π^{-}) invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, X(1840) and X(1880). The new state X(1880) is observed with a statistical significance larger than 10σ. The mass and width of X(1880) are determined to be 1882.1±1.7±0.7 MeV/c^{2} and 30.7±5.5±2.4 MeV, respectively, which indicates the existence of a pp[over ¯] bound state.

Observation of Significant Flavor-SU(3) Breaking in the Kaon Wave Function at 12

We present cross sections for the reaction e^{+}e^{-}→K_{S}^{0}K_{L}^{0} at center-of-mass energies ranging from 3.51 to 4.95 GeV using data samples collected in the BESIII experiment, corresponding to a total integrated luminosity of 26.5 fb^{-1}. The ratio of neutral-to-charged kaon form factors at large momentum transfers (12

Observation of D

We perform for the first time an amplitude analysis of the decay D^{+}→K_{S}^{0}π^{+}η and report the observation of the decay D^{+}→K_{S}^{0}a_{0}(980)^{+} using 2.93 fb^{-1} of e^{+}e^{-} collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. As the only W-annihilation-free decay among D to a_{0}(980) pseudoscalar, D^{+}→K_{S}^{0}a_{0}(980)^{+} is the ideal decay in extracting the contributions of the W-emission amplitudes involving a_{0}(980) and to study the final-state interactions. The absolute branching fraction of D^{+}→K_{S}^{0}π^{+}η is measured to be (1.27±0.04_{stat}±0.03_{syst})%. The branching fractions of intermediate processes D^{+}→K_{S}^{0}a_{0}(980)^{+} with a_{0}(980)^{+}→π^{+}η and D^{+}→π^{+}K[over ¯]_{0}^{*}(1430)^{0} with K[over ¯]_{0}^{*}(1430)^{0}→K_{S}^{0}η are measured to be (1.33±0.05_{stat}±0.04_{syst})% and (0.14±0.03_{stat}±0.01_{syst})%, respectively.

Study of the f_{0}(980) and f_{0}(500) Scalar Mesons through the Decay D_{s}

Using e^{+}e^{-} collision data corresponding to an integrated luminosity of 7.33 fb^{-1} recorded by the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, we present an analysis of the decay D_{s}^{+}→π^{+}π^{-}e^{+}ν_{e}, where the D_{s}^{+} is produced via the process e^{+}e^{-}→D_{s}^{*±}D_{s}^{∓}. We observe the f_{0}(980) in the π^{+}π^{-} system and the branching fraction of the decay D_{s}^{+}→f_{0}(980)e^{+}ν_{e} with f_{0}(980)→π^{+}π^{-} measured to be (1.72±0.13_{stat}±0.10_{syst})×10^{-3}, where the uncertainties are statistical and systematic, respectively. The dynamics of the D_{s}^{+}→f_{0}(980)e^{+}ν_{e} decay are studied with the simple pole parametrization of the hadronic form factor and the Flatté formula describing the f_{0}(980) in the differential decay rate, and the product of the form factor f_{+}^{f_{0}}(0) and the c→s Cabibbo-Kobayashi-Maskawa matrix element |V_{cs}| is determined for the first time to be f_{+}^{f_{0}}(0)|V_{cs}|=0.504±0.017_{stat}±0.035_{syst}. Furthermore, the decay D_{s}^{+}→f_{0}(500)e^{+}ν_{e} is searched for the first time but no signal is found. The upper limit on the branching fraction of D_{s}^{+}→f_{0}(500)e^{+}ν_{e}, f_{0}(500)→π^{+}π^{-} decay is set to be 3.3×10^{-4} at 90% confidence level.

Determination of the Σ

Based on data samples collected with the BESIII detector at the BEPCII collider, the process e^{+}e^{-}→Σ^{+}Σ[over ¯]^{-} is studied at center-of-mass energies sqrt[s]=2.3960, 2.6454, and 2.9000 GeV. Using a fully differential angular description of the final state particles, both the relative magnitude and phase information of the Σ^{+} electromagnetic form factors in the timelike region are extracted. The relative phase between the electric and magnetic form factors is determined to be sinΔΦ=-0.67±0.29(stat)±0.18(syst) at sqrt[s]=2.3960 GeV, ΔΦ=55°±19°(stat)±14°(syst) at sqrt[s]=2.6454 GeV, and 78°±22°(stat)±9°(syst) at sqrt[s]=2.9000 GeV. For the first time, the phase of the hyperon electromagnetic form factors is explored in a wide range of four-momentum transfer. The evolution of the phase along with four-momentum transfer is an important input for understanding its asymptotic behavior and the dynamics of baryons.