39 research outputs found
Inverse spectral problems for Sturm--Liouville operators with matrix-valued potentials
We give a complete description of the set of spectral data (eigenvalues and
specially introduced norming constants) for Sturm--Liouville operators on the
interval with matrix-valued potentials in the Sobolev space
and suggest an algorithm reconstructing the potential from the spectral data
that is based on Krein's accelerant method.Comment: 39 pages, uses iopart.cls, iopams.sty and setstack.sty by IO
Thermodynamics and conformal properties of XXZ chains with alternating spins
The quantum periodic XXZ chain with alternating spins is studied. The
properties of the related R-matrix and Hamiltonians are discussed. A compact
expression for the ground state energy is obtained. The corresponding conformal
anomaly is found via the finite-size computations and also by means of the
Bethe ansatz method. In the presence of an external magnetic field, the
magnetic susceptibility is derived. The results are also generalized to the
case of a chain containing several different spins.Comment: 28 pages, LaTeX2