264 research outputs found
Fermionization and Hubbard Models
We introduce a transformation which allows the fermionization of operators of
any one-dimensional spin-chain. This fermionization procedure is independent of
any eventual integrable structure and is compatible with it. We illustrate this
method on various integrable and non-integrable chains, and deduce some general
results. In particular, we fermionize XXC spin-chains and study their
symmetries. Fermionic realizations of certain Lie algebras and superalgebras
appear naturally as symmetries of some models. We also fermionize recently
obtained Hubbard models, and obtain for the first time multispecies analogues
of the Hubbard model, in their fermionic form. We comment on the conflict
between symmetry enhancement and integrability of these models. Finally, the
fermionic versions of the non integrable spin-1 and spin-3/2 Heisenberg chains
are obtained.Comment: 24 pages, Latex. Minor typos corrected, one equation adde
Exact integrability of the su(n) Hubbard model
The bosonic su(n) Hubbard model was recently introduced. The model was shown
to be integrable in one dimension by exhibiting the infinite set of conserved
quantities. I derive the R-matrix and use it to show that the conserved charges
commute among themselves. This new matrix is a non-additive solution of the
Yang-Baxter equation. Some properties of this matrix are derived.Comment: 6 pages, LaTeX. One reference adde
Multiplicity in Supersymmetric Spin Chains
We discuss a simple procedure for obtaining new integrable spin chains from
old by replacing each single state of the original model by some collection of
states. This works whenever the Lax matrix of the chain has a certain form. The
simplest example is the su(n) XX model. We apply the techniques of the nested
algebraic Bethe ansatz to solve such systems, in the bosonic and supersymmetric
cases.Comment: 14 pages. v2: Added references and minor corrections; v3:
Acknowledgement adde
Integrable open boundary conditions for XXC models
The XXC models are multistate generalizations of the well known spin 1/2 XXZ
model. These integrable models share a common underlying su(2) structure. We
derive integrable open boundary conditions for the hierarchy of conserved
quantities of the XXC models . Due to lack of crossing unitarity of the
R-matrix, we develop specific methods to prove integrability. The symmetry of
the spectrum is determined.Comment: Latex2e, 10 page
On the integrability of the SU(N) Hubbard model
We exhibit explicitly the intertwiner operator for the monodromy matrices of
the recent proposed SU(N) Hubbard model [5]. This produces a new family of
non-additive R-matrices and generalizes an earlier result by Shastry [2].Comment: 4 page
Logarithmic Yangians in WZW models
A new action of the Yangians in the WZW models is displayed. Its structure is
generic and level independent. This Yangian is the natural extension at the
conformal point of the one unravelled in massive theories with current
algebras. Expectingly, this new symmetry of WZW models will lead to a deeper
understanding of the integrable structure of conformal field theories and their
deformations.Comment: 8 pages, TeX, harvmac, 2 .eps figure
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