论文标题
玻色系统激发的声子和光子旋转分支
Phonon and optical-roton branches of excitations of the Bose system
论文作者
论文摘要
对于大量玻璃颗粒的系统，可以获得一个磁场运算符平均值的耦合方程链。在仅考虑一个场合运算符的平均值和两个操作员在零温度下的两个算子的平均值的近似值中，就会得出一个动态方程式的封闭系统。考虑到颗粒之间相互作用势的有限范围，计算了许多粒子玻色系统的基本激发频谱，并表明它具有两个分支：声音分支和一个具有零动量能量隙的光学分支。在高密度下，两个分支都是非单调的，并且具有旋转状的minima。考虑了光谱的声子部分的分散。对中子散射的实验进行的计算和分析允许对超流体HE-4中Landau分散曲线的复杂结构发表陈述。
For a system of a large number of Bose particles, a chain of coupled equations for the averages of field operators is obtained. In the approximation where only the averages of one field operator and the averages of products of two operators at zero temperature are taken into account, there is derived a closed system of dynamic equations. Taking into account the finite range of the interaction potential between particles, the spectrum of elementary excitations of a many-particle Bose system is calculated, and it is shown that it has two branches: a sound branch and an optical branch with an energy gap at zero momentum. At high density, both branches are nonmonotonic and have the roton-like minima. The dispersion of the phonon part of the spectrum is considered. The performed calculations and analysis of experiments on neutron scattering allow to make a statement about the complex structure of the Landau dispersion curve in the superfluid He-4.
