## Fachbereich Physik

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#### Year of publication

- 1996 (14) (remove)

#### Keywords

- Ising model (1)
- Monte Carlo (1)
- finite size scaling (1)
- renormalization group (1)
- roughening transition (1)

- Sigma models with A_k singularities in Euclidean spacetime of dimension 0<=D<4 and in the limit N->infinity (1996)
- For the case of the single-O(N)-vector linear sigma models the critical behaviour following from any A_k singularity in the action is worked out in the double scaling limit N->infinity, f_r -> f_r^c, 2 <= r <= k. After an exact elimination of Gaussian degrees of freedom, the critical objects such as coupling constants, indices and susceptibility matrix are derived for all A_k and spacetime dimensions 0 <= D <= 4. There appear exceptional spacetime dimensions where the degree k of the singularity A_k is more strongly constrained than by the renormalizability requirement.

- The structure of the quantum mechanical state space and induced superselection rules (1996)
- The role of superselection rules for the derivation of classical probability within quantum mechanics is investigated and examples of superselection rules induced by the environment are discussed.

- The Roughening Transition of the 3D Ising Interface: A Monte Carlo Study (1996)
- Abstract: We study the roughening transition of an interface in an Ising system on a 3D simple cubic lattice using a finite size scaling method. The particular method has recently been proposed and successfully tested for various solid on solid models. The basic idea is the matching of the renormalization-groupflow of the interface with that of the exactly solvable body centered cubic solid on solid model. We unambiguously confirm the Kosterlitz-Thouless nature of the roughening transition of the Ising interface. Our result for the inverse transition temperature K_R = 0.40754(5) is almost by two orders of magnitude more accurate than the estimate of Mon, Landau and Stauffer [9].