New Realization of N=2 Supersymmetric QuantumMechanics and Shape Invariance

The new supercharges are constructed and the weight function is defined to study the N=2 one-dimensional supersymmetric quantum mechanics. Several examples are discussed in the new realization.     

硼/氮掺杂富勒烯C20芳香性的争论

用拓扑共振能(TRE)和百分拓扑共振能(%TRE)方法对硼和氮掺杂富勒烯C20的芳香性进行了研究, 并与核独立化学位移(NICS)方法的结果进行了比较. 研究结果表明, 在C20-2nX2n(X=B, N; n=1,2,3,4)中只有C16N4, C14N6和C12N8具有芳香性, 而其它化合物都具有反芳香性. 这与NICS方法的预测结果不一致. 对NICS判据和TRE方法对C20和C20-2nX2n(B, N; n=1,2,3,4)的芳香性进行判断时所得出的不一致结果及其原因进行了讨论, 认为用NICS判据和2(n+1)2规则对这些化合物芳香性的预测是不可靠的.     

Observation of a broad 1-- resonant structure around 1.5 GeV/c2 in the K+K- mass spectrum in J/psi-->K+K-pi0

A broad peak is observed at low K+K- invariant mass in J/psi-->K+K-pi(0) decays found in a sample of 5.8x10(7) J/psi events collected with the BESII detector. The statistical significance of the broad resonance is much larger than 5sigma. A partial wave analysis shows that the J;{PC} of this structure is 1--. Its pole position is determined to be [1576(-55)(+49)(stat)-91+98(syst)] MeV/c(2)-i/2[818(-23)(+22)(stat)-133+64(syst)] MeV/c(2). These parameters are not compatible with any known meson resonances.     

Highly Sensitive and Selective Fluorometric/Electrochemical Dual‐Channel Sensors for TNT and DNT Explosives

A novel electro‐active compound, TCAC , is synthesized and its electrochemical polymerized film is used to detect 2,4,6‐trinitrotoluene (TNT) and 2,4‐dinitrotoluene (DNT) explosives through a fluorometric/electrochemical dual‐channel sensor with high sensitivity and selectivity. In particular, the electrochemical sensor for the analysis of TNT had an enhanced sensitivity of 0.5 μM . The detection limit of the sensor was calculated to be 15 nM .     

Spin-parity analysis of pp¯ mass threshold structure in J/ψ and ψ(3686) radiative decays

A partial wave analysis of the ppˉ mass-threshold enhancement in the reaction J/ψ→γppˉ is used to determine its J(PC) quantum numbers to be 0(-+), its peak mass to be below threshold at M=1832(-5)(+19)(stat)(-17)(+18)(syst)±19(model) MeV/c(2), and its total width to be Γ<76 MeV/c(2) at the 90% C.L. The product of branching ratios is measured to be BR[J/ψ→γX(ppˉ)]BR[X(ppˉ)→ppˉ]=[9.0(-1.1)(+0.4)(stat)(-5.0)(+1.5)(syst)±2.3(model)]×10(-5). A similar analysis performed on ψ(3686)→γppˉ decays shows, for the first time, the presence of a corresponding enhancement with a production rate relative to that for J/ψ decays of R=[5.08(-0.45)(+0.71)(stat)(-3.58)(+0.67)(syst)±0.12(model)]%.     

First observation of η(1405) decays into f(0)(980)π0

The decays J/ψ → γ π+ π- π0 and J/ψ → γ π0 π0 π0 are analyzed using a sample of 225×10(6) J/ψ events collected with the BESIII detector. The decay of η(1405) → f(0)(980)π0 with a large isospin violation is observed for the first time. The width of the f(0)(980) observed in the dipion mass spectra is anomalously narrower than the world average. Decay rates for three-pion decays of the η' are also measured precisely.     

Measurement of J/ψ decays into ΛΛ π+π-

Based on 58 million J/ψ events collected by the BESⅡ detector at the BEPC, J/ψ→ΛΛ π⁺π^- is observed for the first time. The branching fraction is measured to be Br(J/ψ→ΛΛ π⁺π^-)=(4.30±0.13±0.99)×10^-3, excluding the decays to intermediate states, namely J/ψ→Ξ^-Ξ⁺, J/ψ→Σ(1385)^-Σ(1385)⁺, and J/ψ→Σ(1385)⁺Σ(1385)^-. The branching fractions for these intermediate resonance channels are measured to be:Br(J/ψ→Ξ^-Ξ⁺)=（0.90±0.03±0.18）×10^-3, Br(J/ψ→Σ(1385)^-Σ(1385)⁺)=(1.23±0.07±0.30)×10^-3,and Br(J/ψ→Σ(1385)⁺Σ(1385)^-)=(1.50±0.08±0.38)×10^-3, respectively. The angular distribution is of the form dN/d(cosθ)α(1+αcos²θ) with α=(0.35±0.29±0.06) for J/ψ→Ξ^-Ξ⁺, α=(-0.54±0.22±0.10) for J/ψ→Σ(1385)^-Σ(1385)⁺, and α=(-0.35±0.29±0.06) for J/ψ→Σ(1385)⁺Σ(1385)^-.     

Search for invisible decays of eta and eta' in J/psi --> phi eta and phi eta'

Using a data sample of 58 x 10(6) J/psi decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of eta and eta' in J/psi to phi eta and phi eta' are performed. The phi signals, which are reconstructed in K+K- final states, are used to tag the eta and eta' decays. No signals are found for the invisible decays of either eta or eta', and upper limits at the 90% confidence level are determined to be 1.65 x 10(-3) for the ratio B(eta-->invisible)/B(eta --> gamma gamma) and 6.69 x 10(-2) for B(eta' --> invisible)/B(eta' --> gammagamma). These are the first searches for eta and eta' decays into invisible final states.     

Confirmation of the X(1835) and observation of the resonances X(2120) and X(2370) in J/ψ→γπ+π-η'

With a sample of (225.2±2.8)×10(6) J/ψ events registered in the BESIII detector, J/ψ→γπ(+)π(-)η(') is studied using two η(') decay modes: η(')→π(+)π(-)η and η(')→γρ(0). The X(1835), which was previously observed by BESII, is confirmed with a statistical significance that is larger than 20σ. In addition, in the π(+)π(-)η(') invariant-mass spectrum, the X(2120) and the X(2370), are observed with statistical significances larger than 7.2σ and 6.4σ, respectively. For the X(1835), the angular distribution of the radiative photon is consistent with expectations for a pseudoscalar.     

PCA法在分析大气气溶胶常量参数之间相关性分析中的应用

本研究采用日本产NL-20型气溶胶采集器采集大气气溶胶,测定了其溶解液的pH值和电导率．并用PCA（Principal Component Analysis）方法分析了五种因素之间的相关关系得出,TsP的浓度与电导率和相对湿度呈现显著正相关性,而TSP的浓度与pH值和温度呈现出负相关．