A New Mechanism for Low Energy Pion Induced Double Charge Exchange Reaction

Using a method developed in theory of double beta decay[1], we propose a new mechanism, namely the two-nucleon pion absorption-emission mechanism for pion double charge exchange reaction at low energies. The calculations are compared with the experimental data of the angular distribution at 50 MeV and the 0° excitation functions of the DCX reactions on ¹⁴C, ¹⁸O with energies < 130 MeV. It is found that the contribution of this new mechanism is very important at low energies.     

QUARKONIUN POTENTIAL MODEL WITH A NON-ZERO GLUON EFFECTIVE MASS

According to Parisi's suggestion, we assume that the gluon possesses a non-zero effective mass μ. From the assumption we derive an effective Hamiltonian up to order β₂ for quarbnium. For μ=0.8GeV and 0.4 GeV, we find the spectra as well as the relative leptonic widths for charmonium upsilon, which are in good agreement with experiment.     

A POSSIBLE FIREBALL THEORY WITH SUPERSYMMETRY BETWEEN QUARK AND ANTIDIQUARK

A fireball theory in the quark level with supersymmetry between quark and antidiquark is suggested. A preliminary study of this model indicates that it can well describe all characteristic phenomena of multiproduction. In particular, the appearance of diquarks will enhance the baryon yield in multiproduction.     

THE APPROXIMATE B-S WAVE FUNCTIOPiS FOR (XU) ATOM AND THE DECAY RATE FOR E°→(∑+μ-)+νμ

In this paper, the Bethe-Salpeter equation for a Coulombic bound system consisting of a fermion (mass m_l and spin 1/2) and an anti-fermion (mass m₂ and spin 1/2) is solved. The approximate B-S wave functions for (∑U) atom are given. Utilizing the perturbative expansion of the quantum field theory of composite particles, the decay rate and branching ratio for E°→(∑⁺μ^-)+ν_μ are calculated with accuracy up to order O(α).     

HOW TO DETERMINE THE NUCLEAR MATRIX ELEMENT IN 2β-Decay?-A DISCUSSION OF PCAC, 2β-DECAY AND DOUBLE-CHARGE EXCHANGE REACTION OF PIONS ON NUCLEI

It is shown that by applying PCAC, the 2β-decay process can be directly related to double-charge-exchange reaction. Therefore, by studying double-charge-exchange reactions one is able to determine the nuclear matrix element of the relevant 2β-decay experimentally. A preliminary analysis has indicated that if the experimental data of forward-angle cross section on Ca⁴⁰ with pion beam at 164 Mev^[9] are used and extrapolated to Ca⁴⁸, then the squared nuclear matrix element thus determined is smaller than that calculated for Ca⁴⁰→Ti⁴⁸+2e^-+2v^[11] by 10⁵～10⁶.     

IS 40Ca A STABLE ISOTOPE?

It is shorn that the double magic nucleus ⁴⁰Ca is unstable with respect to the double K-electron capture ⁴⁰Ar. By using the shell model wave functions for both ⁴⁰Ca and ⁴⁰Ar, the lifetime of ⁴⁰Ca is estimated as 1.2×10³³yrs.     

Doob's inequality,Burkholder-Gundy inequality and martingale transforms on martingale Morrey spaces

We introduce the martingale Morrey spaces built on Banach function spaces. We establish the Doob's inequality, the Burkholder-Gundy inequality and the boundedness of martingale transforms for our martingale Morrey spaces. We also introduce the martingale block spaces. By the Doob's inequality on martingale block spaces, we obtain the Davis' decompositions for martingale Morrey spaces.     

铝单晶体滑移的电子显微镜颧察(二)

金屠的纯度和试样表面的处理等因素能影响品体滑移的形熊.     

基于银膜孔阵列超强透射效应的相敏表面等离子体共振传感器的仿真研究(英文)

We present an ultra compact and high resolution free space optical spectrometer and demonstrate it by using FDTD simulations. The miniature interferometer-based spectrometer is a series of submicron phase objects on a polymethyl methacrylate(PMMA) film with a CCD as the detector. The spectrum is obtained by solving a system of simultaneous linear equations. The Tikhonov regularization method is used to achieve a resolution at the picometer level. Compared with conventional spectrometers, the proposed device...     

部分屏蔽多极电子鎗聚焦问题

本文对于在有磁场下多阳极电子鎗的电子注聚焦问题进行了理论分析。阴极处磁场可以具有任意屏蔽程度,得到了在加速场内描写电子轨迹的傍轴方程的解析解。在理论分析中,考虑了包括空间电荷效应的情况。