Linear Response in an Interacting Boson System

Structure Functions in an Interacting Boson System*

3m (k) = dw d~S(k ,.,) for a system of Bosons of mass m at zero temperature and density n to the first approximation beyond the Bogoliubov (zeroth) approximation. The two-body interaction u is characterized by the s-wave scatteringlength and is taken to be a constant in k-space. The small dimensionless parameter g = 4irams 0, where s0 = (4iran) 1/2/m is the phonon speed in the zeroth approximat...

Quasidynamical symmetry in an interacting boson model phase transition.

The apparent persistence of symmetry in the face of strong symmetry-breaking interactions is examined in a many-boson model. The model exhibits a transition between two phases associated with U(5) and O(6) symmetries, respectively, as the value of a control parameter progresses from 0 to 1. The remarkable fact is that, in spite of strong mixing of the symmetries for intermediate values of the c...

Nonlinear current response of an isolated system of interacting fermions.

Nonlinear real-time response of interacting particles is studied on the example of a one-dimensional tight-binding model of spinless fermions driven by electric field. Using equations of motion and numerical methods we show that for a nonintegrable case at finite temperatures the major effect of nonlinearity can be taken into account within the linear response formalism extended by a renormaliz...

Symmetries in the Interacting Boson Model

We study the energy level statistics of the states in U(5) and O(6) dynamical symmetries of the interacting boson model and the high spin states with backbending in U(5) symmetry. In the calculations, the degeneracy resulting from the additional quantum number is eliminated manually. The calculated results indicate that the finite boson number N effect is prominent. When N has a value close to ...

Expansion of an Interacting Boson Condensate: the Role of Dimensionality