Physics of Atomic Nuclei
Boson-fermion Holstein-Primakoff mapping at nonzero temperatures for the example of the Lipkin model
A.I. Vdovin, Alan A. Dzhioev, Aleksej Nikolaevich Storozhenko
Abstract
Within the formalism of thermo field dynamics, the boson-fermion Holstein-Primakoff transformation is constructed for the case of nonzero temperatures. For the example of the Lipkin model, the transformation in question is used to construct a thermal Hamiltonian in the form of an expansion in the parameter $${1 \mathord{\left/ {\vphantom {1 {\sqrt N }}} \right. \kern-\nulldelimiterspace} {\sqrt N }}$$ , where N is the number of particles in the system. The temperature dependence of quasiparticle (fermion) and collective-excitation (boson) energies is calculated to terms of order 1/N.