We show that it is possible to restore the symmetry associated with the Goldstone mode within the Self Consistent Random Phase Approximation (SCRPA) applied to the three-level Lipkin model. We determine one and two-body densities as very convergent expansions in terms of the generators of the RPA basis. We show that SCRPA excitations correspond to the heads of some rotational bands in the exact...

The paper describes a method for estimation of the orientation of 3D objects without point correspondence information. It is based on decomposition of the object onto a basis of spherical harmonics. Tensors are obtained, and their normalization provides the orientation of the object. Theoretical and experimental results show that the approach is more accurate than the classical method based on ...

Radio astronomical observations are increasingly corrupted by radio frequency interferences (RFIs), and real time filtering algorithms are becoming essential. In this paper, it is shown how spatial processing techniques can limit the impact of the incoming RFIs for phased array radio telescopes. The proposed approaches are based on estimation of the RFI spatial signature. It requires the diagon...

We develop a "self-avoiding walks" approximation and use it to calculate the spectral function of single hole introduced into 2D square lattice Ising antiferromagnet. The obtained local qualitatively agrees with exact diagonalisation result is largely incoherent. Such stays in contrast spectrum on Bethe lattice, which consists well-separated quasiparticle-like peaks stems from motion an effecti...

In the present paper we investigate approximate analytical diagonalisation of Hamiltonian quantum Rabi model written in Coulomb gauge and taking into account invariance system. It is shown that can be diagonalised with high accuracy on basis a unitary operator transformation utilising simple set state vectors. essential obtained expressions do not depend variational parameters are valid within ...

We study an effective Hamiltonian generating time evolution of states on intermediate scales in the strong-coupling limit spin-1/2 XXZ model. To leading order, it describes integrable model with local interactions. solve completely by means a coordinate Bethe Ansatz that manifestly breaks translational symmetry. demonstrate existence exponentially many jammed and estimate their stability under ...

The continuum theory of elasticity has been used for more than a century and has applications in many fields of science and engineering. It is very robust, well understood and mathematically elegant. In the isotropic case elastic properties are easily represented, but for non-isotropic materials, even in the simple cubic symmetry, it can be difficult to visualise how properties such as Young’s ...

This paper presents a strategy to accelerate virtually any Poisson solver by taking advantage of s spatial reflection symmetries. More precisely, we have proved the existence an inexpensive block diagonalisation that transforms original equation into set 2s fully decoupled subsystems then solved concurrently. is identical regardless mesh connectivity (structured or unstructured) and geometric c...