π+介子辐射衰变分枝比

本文应用标准微扰方法计算π介子衰变过程中π⁺→e⁺+v+r对π⁺→μ⁺+v的分枝比。文中应用了V-A型普适费米弱作用及沙拉姆提出的强作用,计算结果与目前实验结果没有矛盾。     

π介子的辐射衰变

本文应用V-A型普适费米弱作用由协变性和规范不变性的考虑,利用微扰论,计算了π介子辐射衰变的分枝比。     

π~ 介子辐射衰变分枝比

本文应用标准微扰方法计算π介子衰变过程中π~ →e~ v r对π~ →μ~ v的分枝比。文中应用了V-A型普适费米弱作用及沙拉姆提出的强作用,计算结果与目前实验结果没有矛盾。     

普适费米弱相互作用理论及μ~-介子在原子核上的俘获

一.引言 由Feynnman及Gell-Mann;Sudarshan及Marshak所提出的V-A耦合弱作用已为现有的全部的β衰变的实验所证实。在工作中,作者认为一切弱作用的汉密顿量的形式是一样的,因而提出了普适费米弱相互作用理论(以后简称为普适弱作用理论)。 有些粒子(例如核子)和π介子及K介子有强作用,而有些粒子(例如μ介子)则没有这种作用。由于强作用的影响,物理核子和μ介子衰变的情况便会不同。虽然它们衰变     

K~ 介子衰变的分枝比

一.引言 费曼和盖尔曼以及马夏克和森德香同时提出了费米子之间的普适弱相互作用的理论。将这一理论应用于β衰变现象以及一些其他的弱相互作用现象的研究,得到了很好的结果。将这一理论应用到更多的弱相互作用现象的研究中去是有意义的。我们在本文中以这一理论为基础,讨论K~ 介子下列三种方式的衰变     

■超子的发現

最近又发現一个新的基本粒子——反負克西超子(?)。这个发現是美国耶魯大学小組和欧洲一个物理学家小組分别作出的。在这个实驗里,(?)超子都是和(?)超子一起由高速反貭子与貭子碰撞产生。(?)的平均寿命在10_(-10)秒左右,过了这一段时間,(?)衰变为一个π介子和一个(?)超子,然后(?)又衰变成一个π介子和一个反貭子。由于(?)超子这种第一次衰变成一个超子的衰变方式,又叫做“級联超子”。到現在,尚未发現的(?)超子只剩下中性的(?)了。     

格点规范理论中的ΔI=1/2规则

本文用格点规范理论中的强耦合展开方法,计算K介子│ΔS│=1非轻子衰变的弱相互作用矩阵元,并与实验进行了比较.我们的结果显示了ΔI=1/2增强.     

格点规范理论中的△I=1/2规则

本文用格点规范理论中的强耦合展开方法,计算K介子|△S|=1非轻子衰变的弱相互作用矩阵元,并与实验进行了比较.我们的结果显示了△I=1/2增强.     

K介子稀有衰变及其对Multiscale WalkingTechnicolor模型的限制

在多标度人工色模型框架下计算了荷电PG玻色子π±1和π±8对K介子稀有衰变过程K⁺→π⁺νν,K_L→π⁰νν和K_L→μ⁺μ^－的企鹅图贡献.计算结果表明:(a)荷电PG玻色子可以对K介子稀有衰变分枝比给出1～3个量级的增强;(b)根据现有实验数据,K.Lane等人提出的多标度人工色模型基本被排除.     

β衰变对揭示弱作用本质的贡献(续)

三、守恒矢量流理论与~(12)B和~(12)Bβ能谱形状的测量 新的疑难:g_V~β≈g_μ 实验上发现:β衰变中的矢量耦合常数g~V~β不仅在所有超允许0~ →0~ 跃迁中有惊人的相同,而且与μ衰变中费米型相互作用耦合常数g_μ也几乎一样,误差不超过1～2％,这种极好的一致,本来正是普适费米相互作用所要求的。但是,再进一步考虑,却出现了新的疑难,因为核子不同于μ子,它可以发射或吸收虚π介子,例如P←→P π~0←→n π~ ←→P π~ π~-←→……,因此在它的周围好象包着一层介子云。这层介子云对核子的β衰变必然要产生影响,那么为什么包着介子云的核子会与裸μ子有相同的弱作用呢?这显然是一个令人困惑的问题。     

K+介子衰变的分枝比

The branching ratio of the following three modes of K⁺-meaon decay K⁺→μ⁺+π⁰+ν K⁺→e⁺+π⁰+ν K⁺→μ⁺+ν is calculated by using the theory of the universal Fermi weak interaction proposed by Feymann and others. Perturbation method with cut-off is used. The ratio obtained is 1:1.5:12, which is in fair agreement with the experimental value 1:1:15. It is shown, other conbinations of Fermi interactions can not give result in agreement with experiment.     

Manifestation of Nonuniversality of Lepton Interactions in Spontaneously Violated Mirror Symmetry

Data from the LHCb experiments are indicative of a substantial distinction between the B → K (or K*) + e⁺e^? and B → K (or K*) + μ⁺μ^? branching ratios (April 2017). The branching ratio for the e+e? channel is substantially greater than that for the μ⁺μ^? channel, whereas Standard Model (SM) calculations require that they be equal to each other. The above distinction may suggest the existence of a new interaction changing generations and discriminating between leptons that has couplings that are much greater than and are inverse in strength to the SM fermion couplings to the Higgs boson. Under conditions of spontaneously violated mirror symmetry, the coupling of SM particles to the second Higgs scalar that is inevitably present there and which is in principle heavy possesses precisely these properties. An inverse character of this coupling and its strength are not an additional hypothesis but a necessary condition for qualitatively reproducing, in addition, the observed charged-lepton mass hierarchy and the structure of weak lepton mixing—the Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrix. Within the mirror model being considered, all properties of the new interaction, including its inverse character, are due to the hierarchical character of the quark and charged-lepton mass spectrum.     

K+介子的三体轻子衰变

本文利用色散关系方法,假设普适V-A弱相互作用和奇异矢量流不守恒,从而对形状因子f₀,f₁的色散关系进行一次减去,计算了K_μ3⁺、K_e3⁺衰变中的π⁰能谱,K_μ3⁺衰变中的μ⁺能谱和μ⁺的纵向极化。计算中只考虑了K₁^*(m_*=888MeV)中间态对色散积分的贡献。参数σ取为+2.1的结果和实验在误差范围内相符合。放弃奇异矢量流部分守恒假设与实验符合的程度比保持这一假设要好一些。     

Quasi-relativistic treatment of the low-lying KCs states

The potential energy curves, permanent and transition dipole moments as well as spin-orbit and angular coupling matrix elements between the KCs electronic states converging to the lowest three dissociation limits were evaluated in the basis of the spin-averaged wavefunctions corresponding to pure Hund’s coupling case (a). The quasi-relativistic matrix elements have been obtained for a wide range of internuclear distance by using of small (9-electrons) effective core pseudopotentials of both atoms. The core-valence correlation has been accounted for a large scale multi-reference configuration interaction method combined with semi-empirical core polarization potentials. The static dipole polarizabilities of the ground X¹Σ⁺ and a³Σ⁺ states were extracted from the closed-shell coupled-cluster energies by the finite-field method. Among the singlet and triplet Σ⁺ states manifold the pronounced avoided crossing effect between repulsive walls of the (2,3)³Σ⁺ states has been discovered and analyzed by finite-difference calculation of radial coupling matrix elements. The resulting transition dipole moments and potentials were used to predict radiative lifetimes and emission branching ratios of excited vibronic states while the calculated angular coupling matrix elements were transformed to Λ-doubling constants of the (1,2)¹Π states and magnetic g-factor of the ground state. The accuracies of the present results are discussed by comparing with experimental data and preceding calculations.     

强和弱Y-Y相互作用下的奇异强子物质

把修正的夸克-介子耦合模型推广到包含奇异性的情形， 并用来研究奇异强子物质的状态方程. 从最新的6ΛΛHe双超核的实验导出的弱Λ Λ相互作用和过去采用的强Λ Λ相互作用同时被用于计算. 比较发现， 具有强Λ-Λ相互作用的系统束缚得比正常核物质要紧， 而具有弱Λ Λ相互作用的系统则比正常核物质束缚得要松得多. 无论强还是弱相互作用情况， 为了合适地描述修正的夸克 介子耦合模型中超子-超子（Y Y）相互作用， 必须引进σ*和介子. A modified quark meson coupling (MQMC) model is extended to include Λ hyperons and Ξ hyperons. The extended model is then used to study the equation of state (EOS) for strange hadronic matter. A weak Λ Λ interaction deduced from recent observation of 6ΛΛHe double hypernucleus is adopted in the calculation. The resultant EOS is compared with that deduced from a strong Λ Λ interaction. It is found that while the system with the strong ΛΛ interaction is more deeply bound than ordinary nuclear matter due to the opening of new degrees of freedom， the system with the weak Λ Λ interaction is rather loosely bound compared to the later. It is necessary to introduce the strange mesons σ*and in the MQMC model to describe properly the interaction between the hyperons in either strong or weak ΛΛ interaction case.     

Majorana neutrinos in rare meson decays

The rare meson decays K ⁺ → π ^??⁺?′⁺ and D ⁺ → K ^??⁺?′⁺ (?, ?′ = e, μ), which are induced by Majorana neutrino exchange and which are accompanied by lepton-number nonconservation, are considered. The effects of the meson structure are taken into account on the basis of the Gaussian model for the respective Bethe-Salpeter amplitudes. It is shown that existing direct experimental constraints on the decay branching ratios are overly lenient and therefore give no way to set realistic limits on effective Majorana masses. On the basis of the constraints on the lepton-mixing parameters and neutrino masses from precision measurements of electroweak processes, neutrino-oscillation experiments, searches for neutrinoless double-beta decay of nuclei, and cosmological data, indirect constraints on the branching ratios for the decays in question are obtained and found to be much more stringent than the above direct constraints.     

Effects of Final State Interactions in Pure Annihilation Decay of B+ → D+K0*

The decay of the B ⁺ meson to the D ⁺ and K ⁰* mesons is a pure annihilation decay. For this reason, in the framework of the quantum chromodynamics factorization (QCDF) approach, this decay has a small amplitude and a small branching ratio. In this research we find that, before the D ⁺ and K ⁰* mesons are produced in the final states, pair mesons such as D _s ⁺* and D _s ⁺ρ⁰ are produced. The intermediate-state mesons via the exchange of K ⁰(K ⁰*) and D ⁺(D ⁺*) go to the D ⁺ and K ⁰* final state mesons. However we calculate the B ₊ → D ⁺ K ⁰* decay in two different frameworks. The first framework is the QCDF method and the second one is final state interaction (FSI). The experimental branching ratio of B ₊ → D ₊ K ⁰* decay is less than 3 × 10^–6, and our results obtained by the QCDF method and FSI are (0.35 ± 0.04) × 10^–6 and (2.94 ± 0.10) × 10^–6, respectively.     

The Weinberg-Salam model and weak radiative decays of KL mesons

Weak radiative decays K_L → 2γ and K_L → π⁺π^?γ are considered in the Weinberg-Salam model for weak interactions and in the framework of asymptotically free gauge theory (AFGT) for strong interactions (SI). The problem of calculation of the decays at short and large distances is discussed. It is shown that only the large distance contribution is essential for each decay. The estimates of these contributions being rough, it proves impossible to compare them with experiment. However, using anomalous PCAC theory we derive the relation connecting the contributions for these two decays and, hence, the decay amplitudes via the known constants. Experimental data confirm the obtained result. The important result of the paper is that the matrix elements of the effective Hamiltonian specifying the decays at short distances are not dynamically enhanced, unlike the case of weak non-leptonic amplitudes.     

Beta-decay branching ratios of 62Ga

Beta-decay branching ratios of ⁶²Ga have been measured at the IGISOL facility of the Accelerator Laboratory of the University of Jyv?skyl?. ⁶²Ga is one of the heavier T _z = 0 , 0⁺ → 0⁺ β -emitting nuclides used to determine the vector coupling constant of the weak interaction and the V_ud quark-mixing matrix element. For part of the experimental studies presented here, the JYFLTRAP facility has been employed to prepare isotopically pure beams of ⁶²Ga . The branching ratio obtained, BR = 99.893(24) %, for the super-allowed branch is in agreement with previous measurements and allows to determine the ft value and the universal Ft value for the super-allowed β -decay of ⁶²Ga .