Strong coupling constants of light pseudoscalar mesons with heavy baryons in QCD

We calculate the strong coupling constants of light pseudoscalar mesons with heavy baryons within the light cone QCD sum rules method. It is shown that sextet–sextet, sextet–antitriplet and antitriplet–antitriplet transitions are described by one universal invariant function for each class. A comparison of our results on the coupling constants with the predictions existing in literature is also presented.     

Weak decay constants of light and heavy pseudoscalar mesons

We investigate the weak leptonic decays of light and heavy pseudoscalar mesons in a relativistic quark model of independent quarks. We perform a static calculation of the decay constantf _M purely on grounds of simplicity. In order to minimize the possible uncertainty in the static calculation, we estimate the ratios of the decay constants which are found to be in good agreement, in the heavy flavor sector, with the predictions of other models available in the literature and existing experimental data. However, there is a noticeable discrepancy in the current prediction for pion decay constant which demonstrates the inherent limitations of the static approximation in the study of non-strange light mesons.     

Masses of S and P wave mesons and pseudoscalar decay constants using a confinement scheme

In the framework of relativistic harmonic confinement model for quarks and antiquarks, the masses of S- and P-wave mesons and pseudoscalar decay constants from light flavour to heavy flavour sectors are computed. The residual two-body Coulomb interaction and the spin-dependent interaction of the confined one gluon exchange effects (COGEP) such as spin-spin and spin-orbit interactions are perturbatively incorporated with the confinement energy to get the respective vector-pseudoscalar meson mass differences. Here we employ the same parametrization and model parameters as used in a recent study of low-lying hadron masses and leptonic decay widths. The results are being compared with the values obtained from other theoretical models and the experimental values.     

Static and dynamic properties of pseudoscalar mesons

We report the results of form factors, charge radii and decay constants of both light and heavy flavoured pseudoscalar mesons in a QCD inspired quark model. We use the quantum mechanical perturbation theory and discuss its limitations in the present problem. Several predictions are also made for bottom and top flavours.     

Relativistic studies of the decay constants of S wave and P wave mesons

Relativistic corrections are important in hadronic physics since even for the heavy hadrons there are sizable relativistic corrections. Therefore one should use a relativistic model to describe the higher excited states. This note summarizes our predictions for the decay constants of the S wave and P wave heavy mesons by means of the instantaneous relativistic Bethe Salpeter equation (Salpeter equation).     

Relativistic studies of the decay constants of S wave and P wave mesons

Relativistic corrections are important in hadronic physics since even for the heavy hadrons there are sizable relativistic corrections. Therefore one should use a relativistic model to describe the higher excited states. This note summarizes our predictions for the decay constants of the S wave and P wave heavy mesons by means of the instantaneous relativistic Bethe Salpeter equation （Salpeter equation）.     

Hierarchy of masses for pseudoscalar and vector mesons

Assuming that quark flavors beyond isospin, strangeness, and charm exist, we use the relationship between the structure of chiral symmetry breaking of the strong interaction and the Cabibbo angle in order to estimate the masses of the pseudoscalar and vector mesons carrying the fifth (beauty), sixth (truth), and seventh (illusion) quark flavors.     

A Comparative Study of fB within QCD Sum Rules with Two Typical Correlators up to Next-to-Leading Order

The B-meson decay constant f_B is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f_B from two sum rules up to next-to-leading order, i.e. sum rules I and II, which are derived from the conventional correlator and the correlator with chiral currents respectively. It is found that these two sum rules are consistent with each other. The sum rules II involves less non-perturbative condensates as that of sum rules I, and in principle, it can be more accurate if we know the dimension-four gluon condensate well. It is found that f_B decreases with the increment of m_B, and to compare with the Belle experimental data on f_B, both sum rules I and II prefer smaller pole b-quarkmass, m_b=4.68±0.07 GeV. By varying all the input parameters within their reasonable regions and by adding all the uncertainties in quadrature, we obtain f_B=172^{+23}_{-25} MeV for sum rules I and f_B=214_{-34}^{+26} MeV for sum rules II.     

Understanding the radiative decays of vector charmonia to light pseudoscalar mesons

We show that the newly measured branching ratios of vector charmonia (J/ψ$J/\psi$, ψ^′${\psi }^{\prime }$ and ψ(3770)$\psi (3770)$) into γP, where P   stands for light pseudoscalar mesons π⁰${\pi }^0$, η  , and η^′${\eta }^{\prime }$, can be well understood in the framework of vector meson dominance (VMD) in association with the ηc–η(η^′)${\eta }_c\text{–}\eta ({\eta }^{\prime })$ mixings due to the axial gluonic anomaly. These two mechanisms behave differently in J/ψ$J/\psi$ and ψ^′→γP${\psi }^{\prime }\to \gamma P$. A coherent understanding of the branching ratio patterns observed in J/ψ(ψ^′)→γP$J/\psi ({\psi }^{\prime })\to \gamma P$ can be achieved by self-consistently including those transition mechanisms at hadronic level. The branching ratios for ψ(3770)→γP$\psi (3770)\to \gamma P$ are predicted to be rather small.     

Alpha Decay Half-Lives of Some Nuclei from Ground State to Ground State with Yukawa Proximity Potential

We study the half-lives of some nuclei via the alpha-decay process from ground state to ground state. To go through the problem, we have considered a potential model with Yukawa proximity potential and have thereby calculated the half-lives. The comparison with the existing data is motivating.     

On Decay of Correlations for Unbounded Spin Systems with Arbitrary Boundary Conditions

We propose a method based on cluster expansion to study the truncated correlations of unbounded spin systems uniformly in the boundary condition and in a possible external field. By this method we study the spin–spin truncated correlations of various systems, including the case of infinite range simply integrable interactions, and we show how suitable boundary conditions and/or external fields may improve the decay of the correlations.     

微扰QCD方法计算稀有衰变B+→D+s(-K)*0

在标准模型中,稀有衰变道B+→D+s(-K)*0只有通过纯湮没图才可以发生.这样这个衰变道的分支比很小.利用基于kT因子化的微扰方法给出分支比的预测,发现它在10-8的量级上.这个衰变道估计在将来的LHC上得到测量,对检验标准模型以及探寻新物理有着重要的意义.     

Alpha Decay Half-Lives of Some Nuclei from Ground State to Ground State with Yukawa Proximity Potential

We study the half-lives of some nuclei via the alpha-decay process from ground state to ground state. To go through the problem, we have considered a potential model with Yukawa proximity potential and have thereby calculated the half-lives. The comparison with the existing data is motivating.     

Mass spectra and decay of mesons under strong external magnetic field

We study the mass spectra and decay process of σ and begin{document}$ pi_0 $end{document} mesons under a strong external magnetic field. To achieve this goal, we deduce the thermodynamic potential in a two-flavor, hot and magnetized Nambu–Jona-Lasinio model. We calculate the energy gap equation through the random phase approximation (RPA). Then we use the Ritus method to calculate the decay triangle diagram and self-energy in the presence of a constant magnetic field B. Our results indicate that the magnetic field has little influence on the mass of begin{document}$ pi_0 $end{document} at low temperatures. However, for quarks and σ mesons, their mass clearly changes, which reflects the influence of magnetic catalysis (MC). The presence of a magnetic field accelerates the decay of the meson while the presence of a chemical potential will decrease the decay process.     

利用铌酸锂晶体制作体全息光栅的设计性实验

利用双光束干涉,通过控制双光束的记录角度,在铌酸锂晶体中写入光折变体全息布拉格光栅.将该光栅应用于光通信系统中作为滤波器使用,利用ASE光源和光谱仪对其进行测试,在1 548nm波长处获得了峰值半高全宽为4nm,衍射效率为10%的滤波效果.     

An Improved Analysis of Masses and Decay Constants of Heavy Flavour Mesons within Variational Approach

We employ the variational method to study the properties such as masses, decay constants, oscillation frequency and branching ratios of leptonic decays of heavy flavour mesons with linear cum coulomb Cornell potential.Gaussian function, Coulomb wave function and Airy function are taken as the trial wave-function of variational method in this study. Our analysis suggests that Gaussian trial wave-function provides results which are in close proximity with the experimental results. We also make a comparison with the results from QCD Sum rules and lattice QCD, as well as with recent PDG data.     

Infrared regularization with vector mesons and baryons

We extend the method of infrared regularization to spin-1 fields coupled to baryons. As an application, we discuss the axial form factor of the nucleon.     

脉冲源法测量次临界系统裂变衰减特性的理论分析和数值模拟

针对点堆动力学理论解释脉冲源法测试原理时存在的问题, 基于无源中子输运方程分析次临界系统总中子数、泄漏γ射线计数率随时间的变化关系。理论分析表明: 脉冲中子源作用结束后(无源条件下), 在一定时间范围内, 泄漏γ射线计数率和总中子数近似成正比, 两者随时间变化服从近似指数衰减规律, 反映系统本身的裂变衰减特性, 可以由总中子数和γ射线计数率求解瞬发中子衰减时间常数。基于蒙特卡罗程序构造类Godiva裸铀球次临界系统, 模拟脉冲中子源作用下中子和γ射线输运过程, 计算总中子数、泄漏γ射线计数率及两者比值随时间的变化关系, 结果与理论分析一致; 利用脉冲源法由总中子数、泄漏γ射线计数率计算瞬发中子衰减时间常数α₀, 得到与α-k迭代一致的α₀。说明总中子数、泄漏γ射线计数率可以准确反映系统本身的裂变衰减特性。此外, 根据理论分析和模拟计算给出脉冲源法可用数据的时间范围, 分析泄漏γ射线计数率和总中子数比值的影响因素。