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- R. Blumenhagen, W. Eholzer, A. Honecker, K. Hornfeck, R. Hübel
- 1995

We construct several quantum coset W-algebras, e.g. sl(2, IR)/ U (1) and sl(2, IR)⊕ sl(2, IR)/ sl(2, IR), and argue that they are finitely nonfreely generated. Furthermore, we discuss in detail their rôle as unifying W-algebras of Casimir W-algebras. We show that it is possible to give coset realizations of various types of unifying W-algebras, e.g. the… (More)

- R. Blumenhagen, W. Eholzer, A. Honecker, K. Hornfeck, R. Hübel
- 1994

We show that quantum Casimir W-algebras truncate at degenerate values of the central charge c to a smaller algebra if the rank is high enough: Choosing a suitable parametriza-tion of the central charge in terms of the rank of the underlying simple Lie algebra, the field content does not change with the rank of the Casimir algebra any more. This leads to… (More)

First, an algebraic criterion for integrability is discussed –the so-called 'superintegrability'– and some results on the classification of superintegrable quantum spin Hamiltonians based on sl(2) are obtained. Next, the massive phases of the Z n-chiral Potts quantum spin chain (a model that violates parity) are studied in detail. It is shown that the… (More)

- W. Eholzer, M. Flohr, A. Honecker, R. Hübel, W. Nahm, R. Varnhagen
- 1992

In conformal field theory we investigate the representations of recently discovered W-algebras with a single generator in addition to the Virasoro field. We show that many of these W-algebras have only a finite number of highest weight representations. We describe methods for the classification and give complete lists. In a sporadic case we determine… (More)

- M E Zhitomirsky, A Honecker, O A Petrenko
- Physical review letters
- 2000

We predict that an external field can induce a spin ordering in highly frustrated classical Heisenberg magnets. We find analytically stabilization of collinear states by thermal fluctuations at a one-third of the saturation field for kagome and garnet lattices and at a half of the saturation field for pyrochlore and frustrated square lattices. This effect… (More)

- A. Honecker, I. Peschel
- 1996

The hopping motion of classical particles on a chain coupled to reservoirs at both ends is studied for parallel dynamics with arbitrary probabilities. The stationary state is obtained in the form of an alternating matrix product. The properties of one-and two-dimensional representations are studied in detail and a general relation of the matrix algebra to… (More)

- A. Honecker, R. Hübel
- 1993

- A. Honecker
- 1993

Many extended conformal algebras with one generator in addition to the Virasoro field as well as Casimir algebras have non-trivial outer automorphisms which enables one to impose 'twisted' boundary conditions on the chiral fields. We study their effect on the highest weight representations. We give formulae for the enlarged rational conformal field theories… (More)

- A. Honecker
- 2003

Plateaus can be observed in the zero-temperature magnetization curve of quantum spin systems at rational values of the magnetization. In one dimension, the appearance of a plateau is controlled by a quantization condition for the magnetization which involves the length of the local spin and the volume of a translational unit cell of the ground state. We… (More)

- W. Eholzer, A. Honecker
- 1998

Fermionic and bosonic ghost systems are defined each in terms of a single vertex algebra which admits a one-parameter family of conformal structures. The observation that these structures are related to each other provides a simple way to obtain character formulae for a general twisted module of a ghost system. The U (1) symmetry and its subgroups that… (More)