415 research outputs found
Integrable coupling in a model for Josephson tunneling between non-identical BCS systems
We extend a recent construction for an integrable model describing Josephson
tunneling between identical BCS systems to the case where the BCS systems have
different single particle energy levels. The exact solution of the generalized
model is obtained through the Bethe ansatz.Comment: 8 pages, latex, to appear in edition of Int. J. Mod. Phys. B
commemorating the 70th birthday of F.Y. W
Some spectral equivalences between Schrodinger operators
Spectral equivalences of the quasi-exactly solvable sectors of two classes of
Schrodinger operators are established, using Gaudin-type Bethe ansatz
equations. In some instances the results can be extended leading to full
isospectrality. In this manner we obtain equivalences between PT-symmetric
problems and Hermitian problems. We also find equivalences between some classes
of Hermitian operators.Comment: 14 page
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.
Inhomogeneous scalar field solutions and inflation
We present new exact cosmological inhomogeneous solutions for gravity coupled
to a scalar field in a general framework specified by the parameter .
The equations of motion (and consequently the solutions) in this framework
correspond either to low-energy string theory or Weyl integrable spacetime
according to the sign of . We show that different inflationary
behaviours are possible, as suggested by the study of the violation of the
strong energy condition. Finally, by the analysis of certain curvature scalars
we found that some of the solutions may be nonsingular.Comment: LaTex file, 14 page
Algebraic Bethe ansatz for the gl(12) generalized model II: the three gradings
The algebraic Bethe ansatz can be performed rather abstractly for whole
classes of models sharing the same -matrix, the only prerequisite being the
existence of an appropriate pseudo vacuum state. Here we perform the algebraic
Bethe ansatz for all models with , rational, gl(12)-invariant
-matrix and all three possibilities of choosing the grading. Our Bethe
ansatz solution applies, for instance, to the supersymmetric t-J model, the
supersymmetric model and a number of interesting impurity models. It may be
extended to obtain the quantum transfer matrix spectrum for this class of
models. The properties of a specific model enter the Bethe ansatz solution
(i.e. the expression for the transfer matrix eigenvalue and the Bethe ansatz
equations) through the three pseudo vacuum eigenvalues of the diagonal elements
of the monodromy matrix which in this context are called the parameters of the
model.Comment: paragraph added in section 3, reference added, version to appear in
J.Phys.
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