On the reactions p + p↦p + Λ + K+ and p + p↦p + Σ0 + K+ near thresholds

The cross-sections for the reactions of the strange production p + p ↦ p + Λ + K⁺ and p + p ↦ p + Σ⁰ + K⁺ near thresholds of the final states pΛK⁺ and pΣ⁰K⁺ are calculated in the effective Lagrangian approach. Our approach is based on the dominant contribution of the one-pion exchange and strong interaction of the colliding protons in the initial state. The theoretical values of the cross-sections agree reasonably well with the experimental data. The polarization properties of the Λ- and Σ⁰-hyperons are discussed.     

On polarization of strange baryons in reactions p + p↦p + Λ0 + K+ and p + p↦p + Σ0 + K+ near thresholds

Polarization properties of strange baryons produced in pp reactions, p + p↦p + Λ⁰ + K⁺ and p + p↦p + Σ⁰ + K⁺, near thresholds of the final states pΛ⁰K⁺ and pΣ⁰K⁺ are analysed relative to polarizations of colliding protons. The cross-sections for pp reactions are calculated within the effective Lagrangian approach accounting for strong pp rescattering in the initial state of colliding protons with a dominant contribution of the one-pion exchange and strong final-state interaction of daughter hadrons (Eur. Phys. J. A 9, 425 (2000)). Received: 22 October 2001 / Accepted: 14 November 2001     

Search for lepton number violating decays B+ → π- μ+ μ+ and B+ → K- μ+ μ+

A search is performed for the lepton number violating decay B+ → h- μ+ μ+, where h- represents a K- or a π-, using an integrated luminosity of 36 pb(-1) of data collected with the LHCb detector. The decay is forbidden in the standard model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B+ → K- μ+ μ+) < 5.4×10(-8) and B(B+ → π- μ+ μ+) < 5.8×10(-8) are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.     

Annihilation of + \bar p + p → e + + e ? + π0 and + \bar p + p → γ + π0 through an ω-Meson intermediate state

The s-channel annihilation of a proton and an antiproton into a neutral pion and a real or virtual photon followed by lepton pair emission is studied. Such a mechanism is expected to play a role at moderate values of the total energy $ \sqrt s $ , when the pion is emitted in the angular region around 90° in the center-of-mass system. A fair comparison with the existing data is obtained taking scattering and annihilation channels into account. The cross section is calculated and numerical results are given in the kinematical range accessible in the PANDA experiment at FAIR.     

Isotopic Effects on Stereodynamics of the C~+ + H_2→CH~+ + H Reaction

The effects of isotope substitution on stereodynamic properties for the reactions C~+ + H_2/HD/HT →CH~+ + H/D/T have been studied applying a quasi classical trajectory method occurring on the new ground state CH_2~+ potential energy surface [J. Chem. Phys. 142(2015) 124302]. In the center of mass coordinates applying the quasi classical trajectory method to investigate the orientation and the alignment of the product molecule. Differential cross section and three angle distribution functions P(θ_r), P(ф_r), P(θ_r, ф_r) on the potential energy surface that fixed the collision energy with a value is 40 kcal/mol have been studied. The isotope effect becomes more and more important with the reagent molecules H_2 changing into HD and HT. P(θ_r, ф_r) as the joint probability density function of both polar angles θ_r and ф_r, which can illustrate more detailed dynamics information. The isotope effect is obvious influence on the properties of stereodynamics in the reactions of C~+ + H_2/HD/HT → CH~+ + H/D/T.     

Cu~+、Ag~+、Au~+与乙硫醇的气相化学反应

利用激光溅射 分子束的技术 ,结合反射飞行时间质谱计 ,研究了Cu+、Ag+、Au+与乙硫醇的气相化学反应。结果显示这三种金属离子与 (CH3 CH2 SH) n 反应形成一系列团簇离子M+(CH3 CH2 SH) n,且团簇离子尺寸不一样。Ag+、Au+与乙硫醇的反应还生成了 (CH3 CH2 SH) +n ,由此推测Cu+、Ag+、Au+与乙硫醇团簇的反应存在两种通道 ,一种通道是生成M+(CH3 CH2 SH) n,另一种是生成 (CH3 CH2 SH) +n 。Cu+、Au+与乙硫醇的反应还生成了M+(H2 S) (M =Cu、Au) ,但是实验中没有观察到Ag+(H2 S) ,理论计算表明Ag+(H2 S)很不稳定。另外 ,分析产物离子M+(CH3 CH2 SH) n 的强度发现 ,n =1～ 2之间存在明显的强度突变现象     

Cu+、Ag+、Au+与乙硫醇的气相化学反应

利用激光溅射-分子束的技术,结合反射飞行时间质谱计,研究了Cu+、Ag+、Au+与乙硫醇的气相化学反应.结果显示这三种金属离子与(CH3CH2SH)n反应形成一系列团簇离子M+(CH3CH2SH)n,且团簇离子尺寸不一样.Ag+、Au+与乙硫醇的反应还生成了(CH3CH2SH)+n,由此推测Cu+、Ag+、Au+与乙硫醇团簇的反应存在两种通道,一种通道是生成M+(CH3CH2SH)n,另一种是生成(CH3CH2SH)+n.Cu+、Au+与乙硫醇的反应还生成了M+(H2S)(M=Cu、Au),但是实验中没有观察到Ag+(H2S),理论计算表明Ag+(H2S)很不稳定.另外,分析产物离子M+(CH3CH2SH)n的强度发现,n=1～2之间存在明显的强度突变现象.     

K+-Na+和Ag+-Na+两步离子交换技术制作玻璃基光波导研究

利用K+-Na+和Ag+-Na+两步离子交换得到掩埋型光波导.该方法抑制Ag+-Na+离子交换时产生的Ag+微粒,降低波导损耗,增加波导截面的圆对称性,从而提高光波导器件的性能.用该方法制作了1×8光功分器,其插入损耗平均为10.9 dB.     

量子色动力学中的e++e-→π+q+q过程

本文利用QCD的渐近自由性质,求出一条腿动量平方固定另一条腿动量平方趋于无穷大时的波函数,并把它应用于计算e⁺+e^-→π+q+（?）过程（其中π介子相对于层子喷注轴有大的横动量）。计算结果表明,这个过程对e⁺+e^-→强子截面的贡献比e⁺+e^-→g+q+（?）过程的贡献小得多。     

求解H=αa~+a+βb~+b+γ(a~+b~++ab)的波函数的简单方法

本文用能生成玻戈留玻夫变换的幺正变换的坐标表象简捷地给出哈密顿量Ｈ＝αａ~＋ａ＋βｂ~＋ｂ＋γ（ａ~＋ｂ~＋＋ａｂ）的波函数．     

可见分光光度法研究In3+与Zr4+、Ce3+、Rh3+和Ga3+的浮选分离

用可见分光光度法研究了溴化四丁基铵-碘化钾-水体系浮选分离铟的行为,探讨了In3+与-些金属离子分离的条件.结果表明,当溶液中溴化四丁基铵和碘化钾的浓度分别为6.0×10-4mol/L和5.0×10-3mol/L时,In3+与Zp+、Ce3+、Rh3+和Ga3+可定量分离.     

Zum Zerfallπ→e+ν+γ

The radiative decay of the chargedπ-mesonπ→e+ν+γ is calculated using dispersion relation techniques. It is assumed that the weak interaction producing the decay has a V-A structure. The decay through the vector variant has been reinvestigated and found to be different from the result ofVaks andIoffe. The theoretical prediction of this paper is in agreement with a preliminary experiment recently performed at CERN.     

主成分回归法同时测定Cu2+、Pb2+、Hg2+和Cd2+

研究了用双硫腙光度法结合多元线性回归技术直接分析水相中有毒重金属离子的方法.结果表明,在β-环糊精和非离子表面活性剂Triton X-100的存在下,金属离子-双硫腙配位体系具有更高的灵敏度和稳定性.使用多元线性回归技术,可以在多种干扰金属离子共存的条件下,不经萃取和化学分离直接分析4种常见的有毒重金属离子.     

Deuteron fragmentationd+p→p+p+n at 9 GeV/c

Gamma-ray energy correlations have been measured for several reactions leading to light-mass Hf isotopes with 160 ?A?166. The correlation spectra show ridge-valley structures up to high rotational frequencies from which a drop in J _c ⁽²⁾ is deduced at high frequencies. This drop suggests that a large portion of the angular momentum is generated by aligning particles. It may also be explained by the theoretically predicted triaxial states with large deformation.     

The p + p → π+ + d reaction close to threshold at COSY

Differential and total cross sections of the p + p → π⁺ + d reaction close to threshold were measured employing a magnetic spectrograph with track reconstruction, a very thin liquid hydrogen target and an accelerated proton beam with high phase space density. The data resolve a previous discrepancy between the n + p → π⁰ + d and the π⁺ + d → 2p reaction close to threshold indicating that isospin symmetry may be broken in the s-wave part of the cross section.     

MgHe~+和BeHe~+光谱的理论研究

用从头算MOLECULE—EPSCF程序计算得到MgHe~+的基电子态~2∑4s和三个激发电子态~2∑3p、~2∏3p、~2∑3s以及BeHe~+的基电子态~2∑3s和二个激发电子态~2∏2p、~2△3d的势能曲线,并在此基础上利用自编的程序计算不态—态间光谱跃迁的Franck—Condon因子。MgHe~+的~2∏3p、~2∑3s都有一个很深的势阱,~2∑4s有一个非常浅的势阱,~2∑3p没有势阱。BeHe~+的~2∏2p、~2△3d各有一个很深的势阱,基电子态~2∑3s有一个非常浅的势阱。     

Sm3+在玻璃中的发光以及Sb6+、Ce6+、Gd3+对Sm3+发光性质的影响

本文研究了单掺(Sm3+,Ce3+、Gd3+.Sb3+、双掺(Sm3++Ce3+、Sm3++Gd3+,Sm3++Sb3+)和兰掺(Sm3++Gd3++Ce3+)约四十余种不同玻璃的发射谱和激发谱.探讨了玻璃成份和掺杂离子浓度对Sm3+发光性质的影响以及Ce3+,Gd3+、Sb3+、Ce3++Gd3+对Sm3+的敏化作用。     

Gd3+,Yb3+和Tm3+共掺杂氟化物纳米晶中Yb3+-Tm3+-Gd3+间的能量传递

用水热法合成了Y_0.8-x-yF₃∶Gd_x³⁺,Yb_0.2³⁺,Tm_y³⁺纳米晶的上转换发光材料。在典型的Y_0.595F₃∶Gd_0.200³⁺,Yb_0.200³⁺, Tm_0.005³⁺纳米微晶中,在980 nm激光激发下,观察到了Tm³⁺的紫外、紫色上转换发射明显增强和来自于Gd³⁺的⁶D_9/2、⁶I_J、⁶P_5/2及⁶P_7/2能级到基态⁸S_7/2能级的紫外发射。通过比较Y_0.8-x-yF₃∶Gd_x³⁺ ,Yb_0.2³⁺,Tm_y³⁺纳米晶样品的上转换发光性质以及Tm³⁺和Gd³⁺中一些激发态的能级寿命,借助于能级图描述了Yb³⁺-Tm³⁺-Ga³⁺之间的有效的能量传递过程。