| Popis: |
The method developed by Boguliubov for an imperfect Bose-Einstein gas is generalized in order to permit examination of a mixture of an arbitrary number of different species of bosons. The generalized method involves diagonalization of a matrix that has a Hermitian-like property by a unitary-like transformation in a space with an indefinite metric. When a neutral mixture of two types of charged bosons is examined, it is found that two types of elementary excitations exist; one having the energy-momentum dispersion relation associated with plasma oscillations at low momenta and another having the energy-momentum relation characteristic of a free particle with a modified mass at very low and high momenta. Further investigation shows that the plasma-type excitation consists of an oscillation in charge density while the free-particle-like excitation consists of an oscillation in mass density. (auth) |
