We consider a vector lattice model for mixtures of water, oil and amphiphile, and it extends to the (unbalanced) case of different water and oil volume fractions, an approach previously developed for the balanced case. After an exact summation of the orientational degrees of freedom we get an...

The small-world network model is a simple model of the structure of social networks, which simultaneously possesses characteristics of both regular lattices and random graphs. The model consists of a one-dimensional lattice with a low density of shortcuts added between randomly selected pairs of...

Taking into account the scattering processes due to random eigenfrequencies and random hopping matrices, we calculate the correlation functions of density fluctuations associated with the particle--hole pairs in the intraband and interband. The correlation functions for the intraband yield sound...

We perform the dimensional reduction of the linear σ model at one-loop level. The effective potential of the reduced theory obtained from the integration over the nonzero Matsubara frequencies is exhibited. Thermal mass and coupling constant renormalization constants are given, as well as the...

Randomly distributed atoms are considered in the harmonic potentials with random eigenfrequencies. The hopping of atoms makes energy dispersion curves of an atom. The correlation functions of density fluctuations in the intraband transition yield the freezing point, where the hopping is...

Using field-theoretical methods and exploiting conformal invariance, we study Casimir forces at tricritical points exerted by long-range fluctuations of the order-parameter field. Special attention is paid to the situation where the symmetry is broken by the boundary conditions (extraordinary...