Experimental study of cesium 5D 5D→6S (nL=9D,11S,7F)energy pooling collisions

We report experimentally the measured rate coefficients for the energy pooling(EP)collisions process Cs(5D) Cs(5D)→Cs(6S) Cs(nL=9D,11S,7F)in cesium densities of 10~(16)-10~(17)cm~(-3).The 5D state was populated via 8S→7P→5D spontaneous emission following two-step pumping 6S→6P_(3/2)→8S. Since the 5D→6P(3.0—3.6μm)fluorescence could not be detected in this experiment,we carried out a relative measurement for the process 6P 5D→6S 7D.The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode laser beam, tuned to 6P_(3/2)→9S_(1/2)transition,which could be translated parallelly to the pump beam.The excited atom densities have been combined with the measured fluorescence ratios to yield EP rate coefficients. The average values for nL=9D,11S and 7F are 8.0±4.0,7.0±3.5,and 9.3±4.6(in units of 10~(-10) cm~3/s),respectively.Influence of the energy transfer process 11S 6S(?)7F 6S on the rate coefficients k_(11S)and k_(7F)is also discussed.     

BaFClxBr1－x:Sm2+中5D2→7F0跃迁几率及其对烧孔效率的影响

本文以BaFClxBr1－x:Sm2+中5D2→7F0的跃迁几率随x变化为中心对BaFClxBr1－x:Sm2+体系4f5d带的激发光谱、5D2→7F0跃迁的荧光衰减随温度的变化特性、5D2→7F0的跃迁几率等进行了研究。从而得出结论:在BaFClxBr1－x:Sm2+中,随Br含量的增大,4f5d带与5D2能级更加接近,使7F0→5D2的吸收截面增大,从而可能提高在5D2:能级烧孔的效率。     

Study of Exclusive Hadronic Decays for D0→Ks0π+π- and D0→Ks0K+K- and Their Resonant Structures

We report the results of an experimental study of the exclusive hadronic decays for D0→K0 sπ+π - and K 0 sK +K - and their resonant structures using BES-Ⅰ detector at the BEPC Collider. Using the data sample of 22.3 pb -1 collected at the center-of-mass energy s=4.03 GeV, we measured the branching fraction for D 0→K 0π +π - to be (5.32±0.53±0.40)%, the branching fractions for the decays D 0→ K *-π +, D 0→K 0ρ 0 and D 0→K 0(π +π -) non-resonant to be (6.05±0.32±0.49)%, (1.17±0.17±0.13)% and (1.35±0.22±0.17)%, respectively. We measured the branching fractions Br(D 0→f) to be (1.04±0.24± 0.16)% for f=K 0K +K -, (1.12±0.34±0.15)% for f=K0, and (0.27±0.13±0.03)% for f=K 0(K+K-)non-.     

Magnetooptical Spectroscopy of the 5D4 → 7F5 Radiative Transition of the Non-Kramers Tb3+ Ion in an Yttrium-Aluminum Garnet

Spectra of luminescence and magnetic circular polarization of luminescence corresponding to the ⁵ D ₄ ⁷ F ₅ radiative transition of the Tb³⁺ ion in an yttrium-aluminum garnet are studied experimentally. In the context of crystalline field theory, the energy spectrum of the ⁷ F ₅ multiplet of the Tb³⁺ ion in the garnet is calculated. The structure of internal energy levels of the ⁷ F ₅ multiplet of the Tb³⁺ ion is refined based on a comparison of the calculated results with the experimental data, and the diagram of magnetooptically active radiating transitions between ⁵ D ₄ and ⁷ F ₅ multiplet energy sublevels is constructed.     

遍举衰变过程D0→Ks0π+π–和D0→Ks0K+K–及其共振态结构的实验研究

利用北京谱仪(BES–Ⅰ)在北京正负电子对撞机(BEPC)e+e–质心系能量为4.03GeV处采集的积分亮度为22.3pb–1的数据,研究了D0→K0sπ+π–,D0→K0sK+K–的衰变及其末态的共振结构.实验测得D0→K0sπ+π–过程的分支比为(5.32±0.53±0.40)%;D0→K–π+,D0→K0ρ0和D0→K0s(π+π–)non resonance过程的分支比分别为(6.05±0.32±0.49)%,(1.17±0.17±0.13)%和(1.35±0.22±0.17)%;测得D0→K0sK+K–,D0→K0和D0→K0(K+K–)non?的分支比分别为(1.04±0.2?4±0?.16)%,(1.12±0.34±0.15)%和(0.27±0.13±0.03)%.     

Analysis of the B 0(+) → J/ΨD 0(+) decays

We analyze B ⁰⁽⁺⁾ → J/ΨD ⁰⁽⁺⁾ decays by considering the contributions of annihilation diagrams. For each diagram, we calculate the branching ratios for various parameters X _A , which have played a significant role in our results. These parameters have been concluded from the divergence integrals in hard-scattering kernels. Here, we have considered three effective variables, including: Λ(225, 500 MeV), ρ _A (0, 1, 1/2), and φ _A . It is found that the most of the obtained data are placed in the experimental range at Λ = 225 MeV and Λ = 500 MeV for B ⁺ → J/ΨD ⁺ and B ⁰ → J/ΨD ⁰, respectively.     

Searches for the decay D 0 → µ+µ− at hadron colliders

Investigations of rare charmed-meson decays are used to test the Standard Model and to perform searches for new physics beyond it. Advances made in searches for the rare decay D ⁰ → µ⁺µ^? in experiments at the HERA and Tevatron hadron colliders and at the LHC over the last few years are considered.     

Hyperfine structures and isotope shifts of the 5d 4 D 7/2→6p 4 P 5/2 0 transition in Xenon ions

Collinear fast beam-laser spectroscopy has been performed on metastable 5d ⁴ D _7/2 Xenon ions. Hyperfine structure constants for the 6p ⁴ P _5/2 ⁰ level have been derived for¹²⁹Xe:A=?1,634.9±0.9 MHz and¹³¹Xe:A=485.3±0.3 MHz andB=?116.5±2.0MHz. Changes in mean squared nuclear charge radii are derived from the measured isotope shifts.     

Cabbibo Suppressed Semileptonic Decay D0→π－e+ve

The transition rate for the Cabibbo suppressed decay d0→π–e+ν e is calculated. This allows the extractions of the form factor |fπ +(0)| and the CKM matrix element |v cd| using the measured branching ratio.     

The decay h0 → A0 → A0A0: a complete one-loop calculation in the MSSM

In the minimal supersymmetric standard model the decay h⁰ → A⁰A⁰ of the light neutral scalar h⁰ is kinematically allowed for low values of tan β when radiative corrections to the neutral Higgs masses are taken into account. The width of this decay mode is revisited on the basis of a complete one-loop diagrammatic calculation. We give the analytical expressions and numerical results and compare them with the corresponding ones from the simpler and compact approximations of the effective potential method and the renormalization group approach.     

Measuring D~0-~0mixing in D→f_0(980)K~* and more

We investigate the D0-0 mixing through the doubly Cabibbo suppressed (DCS) channel D0 →f0(980)K0 and its charge conjugate channel, in which the K0 meson is reconstructed in both K π- and KSπ0 final state. Although the decay D0 →f0(980)K* has a small branching ratio, the final state mesons are relatively easy to identify. The f0(980) meson can be replaced by the S-wave π π- state, or a longitudinally polarized vector meson ρ0. All mixing parameters, including the mass difference and decay width difference,can be extracted by studying the time-dependent decay width of these channels. We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

关于B-0→K-0π0衰变过程研究

系统地计算B^0→K^0π^0衰变过程的强子矩阵元，它包括领头阶因子化部分，αs修正的硬胶子交换部分和软胶子交换部分．其中软胶子交换部分，无论在量子色动力学(QCD)因子化方法中，还是在微扰QCD中都不能进行计算．用光锥QCD求和规则系统地计算了这部分贡献．并发现在该衰变道中软胶子交换部分与领头阶因子化部分以及αs修正的硬胶子交换部分有相同的数量级，因此不能忽略．最后计算了该衰变过程的分支比，计算结果与实验结果相一致．     

The decaysK S 0 →γγ andK L 0 →γγ in the chiral approach

We calculate theK _S ^Emphasis>0 →γγ decay within the approach of non-linear realization of chiralS U(3)×S U(3). The branching ratio with respect to theπ ⁺ π ^- channel turns out to be 3.5×10^?6 and therefore similar to the result gotten previously by dispersion relation techniques in a non-chiral model. We also discuss theK _L ⁰ →γγ decay by taking into account new results onη ₁-η ₈ mixing from recent measurements of the η→γγ decay.     

EuCl3.6H2O中Eu^3＋的^5D0—^7F0跃迁的“反常”温度效应及其跃迁机制研究

研究了ＥｕＣｌ３．６Ｈ２Ｏ的Ｅｕ＾３＋的＾５Ｄ０－＾６Ｆ０“禁戒”跃迁的机制有其“反常”温度效应。通过比较没温度下荧光光谱中＾５Ｄ０－＾６跃迁和＾５Ｄ０－＾７Ｆ０跃迁第一条谱线的强度比，发现由于晶格振动，＾７Ｆ２态通过四个频率为２４５ｃｍ－１的声子与＾７Ｆ０态耦合，使＾７Ｆ０态成为混合态，因而使＾５Ｄ０－＾７Ｆ－的跃迁成为可能，并且其振子强度随温度的变化而变化。     

Final state interaction effects in the B + → D + K 0 decay

The exclusive decay of B ⁺ → D ⁺ K ⁰ is calculated by the QCD factorization method (QCDF) and final state interaction (FSI). First, the B ⁺ → D ⁺ K ⁰ decay is calculated via QCDF method. The result that is found by using the QCDF method is less than the experimental result. So FSI is considered to solve the B ⁺ → D ⁺ K ⁰ decay. For this decay, the D _s ⁺ π⁰, D _s ⁺ *ρ⁰, D _s ⁺ *? via the exchange of \(\bar K^0\) , \(\bar K^{0*} \) , D ^?, and D ^?* mesons are chosen for the intermediate states. The above intermediate states are calculated by using the QCDF method. In the FSI effects, the results of our calculations depend on η as the phenomenological parameter. The range of this parameter is selected from 2 to 2.4. It is found that if η = 2.4 is selected, the numbers of the branching ratio are placed in the experimental range. The experimental branching ratio of this decay is less than 2.9 × 10^?6 and our results calculated by QCDF and FSI are (0.16 ± 0.04) × 10^?6 and (2.8 ± 0.09) × 10^?6, respectively.     

Cabbibo压制半径子衰变过程D0→π－e+ve

计算了Cabibbo压制D0→π－e+ve衰变率.利用计算结果和测得分支比来研究形状因子|fπ +(0)|及CKM矩阵元|v cd|     

Superallowed 0+ → 0+ beta-decay and CKM unitarity

Precise measurements of the ft-values for superallowed nuclear β-decay yield results that support conservation of the weak vector current but violate the unitarity of the Cabibbo-Kobayashi-Maskawa matrix by more than two standard deviations. This apparent violation of the Standard Model has led to considerable theoretical and experimental activity largely focussed on reducing uncertainties in the small correction terms that account for charge-dependent nuclear effects. This activity is outlined and the prospects for future sharpening of the unitarity test are assessed. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: hardy@comp.tamu.edu