ar X iv : c on d - m at / 9 40 40 50 v 1 1 8 A pr 1 99 4 Saddle Points Stability in the Replica Approach Off Equilibrium

ar X iv : c on d - m at / 9 40 50 07 v 1 4 M ay 1 99 4 Interfaces and lower critical dimension in a spin glass model

In this paper we try to estimate the lower critical dimension for replica symmetry breaking in spin glasses through the calculation of the additional free-energy required to create a domain wall between two different phases. This mechanism alone would say that replica symmetry would be restored at the lower critical dimension D c = 2.5.

ar X iv : c on d - m at / 9 50 40 37 v 1 1 1 A pr 1 99 5 . On the Critical Temperature of Non - Periodic Ising Models on Hexagonal Lattices

The critical temperature of layered Ising models on triangular and honeycomb lattices are calculated in simple, explicit form for arbitrary distribution of the couplings.

ar X iv : c on d - m at / 9 50 40 93 v 1 2 4 A pr 1 99 5 An Upsilon Point in a Spin Model

We present analytic evidence for the occurrence of an upsilon point, an infinite checkerboard structure of modulated phases, in the ground state of a spin model. The structure of the upsilon point is studied by calculating interface–interface interactions using an expansion in inverse spin anisotropy. pacs: 05.50.+q 64.40.Cn 75.10.Hk Typeset using REVTEX 1

ar X iv : c on d - m at / 9 40 40 42 v 1 1 4 A pr 1 99 4 Supersolids in the Bose – Hubbard Hamiltonian

We use a combination of numeric and analytic techniques to determine the ground state phase diagram of the Bose–Hubbard Hamiltonian with longer range repulsive interactions. At half filling one finds superfluidity and an insulating solid phase. Depending on the relative sizes of near–neighbor and next near–neighbor interactions, this solid either follows a checkerboard or a striped pattern. In ...

ar X iv : h ep - p h / 98 04 40 7 v 1 2 6 A pr 1 99 8 B c → l ν̄γ DECAY IN LIGHT CONE QCD