102 research outputs found
Doped Heisenberg chains: spin-S generalizations of the supersymmetric t-J model
A family of exactly solvable models describing a spin-S Heisenberg chain
doped with mobile spin-(S-1/2) carriers is constructed from gl(2|1)-invariant
solutions of the Yang-Baxter equation. The models are generalizations of the
supersymmetric t-J model which is obtained for S=1/2. We solve the model by
means of the algebraic Bethe Ansatz and present results for the zero
temperature and thermodynamic properties. At low temperatures the models show
spin charge separation, i.e. contain contributions of a free bosonic theory in
the charge sector and an SU(2)-invariant theory describing the magnetic
excitations. For small carrier concentration the latter can be decomposed
further into an SU(2) level-2S Wess-Zumino-Novikov-Witten model and the minimal
unitary model M_p with p=2S+1.Comment: LaTeX, 24 pp. incl. 4 figure
Doping of a Spin-1 Chain: An Integrable Model
An exactly soluble model describing a spin S=1 antiferromagnetic chain doped with mobile S=1/2 carriers is constructed. In its continuum limit the undoped state is described by three gapless Majorana fermions composing the SU(2) triplet. Doping adds a scalar charge field and a singlet Majorana fermion with different velocity. We argue that this mode survives when the Haldane gap is added
Bethe ansatz solution of the closed anisotropic supersymmetric U model with quantum supersymmetry
The nested algebraic Bethe ansatz is presented for the anisotropic
supersymmetric model maintaining quantum supersymmetry. The Bethe ansatz
equations of the model are obtained on a one-dimensional closed lattice and an
expression for the energy is given.Comment: 7 pages (revtex), minor modifications. To appear in Mod. Phys. Lett.
Doping of a spin-1 chain: integrable model
An exactly soluble model describing a spin S=1 antiferromagnetic chain doped
with mobile S=1/2 carriers is constructed. In its continuum limit the undoped
state is described by three gapless Majorana fermions composing the SU(2)
triplet. Doping adds to this a scalar charge field and a singlet Majorana
fermion with different velocity. We argue that this mode survives when the
Haldane gap is added.Comment: RevTeX, 6 pages, 3 figures; final version, to appear in PR
Finite-Size Scaling Studies of Reaction-Diffusion Systems Part III: Numerical Methods
The scaling exponent and scaling function for the 1D single species
coagulation model are shown to be universal, i.e. they are
not influenced by the value of the coagulation rate. They are independent of
the initial conditions as well. Two different numerical methods are used to
compute the scaling properties: Monte Carlo simulations and extrapolations of
exact finite lattice data. These methods are tested in a case where analytical
results are available. It is shown that Monte Carlo simulations can be used to
compute even the correction terms. To obtain reliable results from finite-size
extrapolations exact numerical data for lattices up to ten sites are
sufficient.Comment: 19 pages, LaTeX, 5 figures uuencoded, BONN HE-94-0
Eight state supersymmetric model of strongly correlated fermions
An integrable eight state supersymmtric model is proposed, which is a
fermion model with correlated single-particle and pair hoppings as well as
uncorrelated triple-particle hopping. It has an supersymmetry and
contains one symmetry-preserving free parameter. The model is solved and the
Bethe ansatz equations are obtained.Comment: Some cosmetic changes; to appear in Phys. Rev.
Heisenberg spin chains based on sl(2|1) symmetry
We find solutions of the Yang-Baxter equation acting on tensor product of
arbitrary representations of the superalgebra sl(2|1). Based on these solutions
we construct the local Hamiltonians for integrable homogeneous periodic chains
and open chains.Comment: 28 pages LATE
Integrable open supersymmetric U model with boundary impurity
An integrable version of the supersymmetric U model with open boundary
conditions and an impurity situated at one end of the chain is introduced. The
model is solved through the algebraic Bethe ansatz method and the Bethe ansatz
equations are obtained.Comment: RevTeX, 8 pages, no figures, final version to appear in Phys. Lett.
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