3 research outputs found
Analytical results for the Coqblin-Schrieffer model with generalized magnetic fields
Using the approach alternative to the traditional Thermodynamic Bethe Ansatz,
we derive analytical expressions for the free energy of Coqblin-Schrieffer
model with arbitrary magnetic and crystal fields. In Appendix we discuss two
concrete examples including the field generated crossover from the SU(4) to the
SU(2) symmetry in the SU(4)-symmetric model.Comment: 5 page
Integrable Circular Brane Model and Coulomb Charging at Large Conduction
We study a model of 2D QFT with boundary interaction, in which two-component
massless Bose field is constrained to a circle at the boundary. We argue that
this model is integrable at two values of the topological angle,
and . For we propose exact partition function in terms
of solutions of ordinary linear differential equation. The circular brane model
is equivalent to the model of quantum Brownian dynamics commonly used in
describing the Coulomb charging in quantum dots, in the limit of small
dimensionless resistance of the tunneling contact. Our proposal
translates to partition function of this model at integer charge.Comment: 20 pages, minor change
Spinons in more than one dimension: Resonance Valence Bond state stabilized by frustration
For two spatially anisotropic, SU(2)-invariant models of frustrated magnets
in arbitrary space dimension we present a non-perturbative proof of the
existence of neutral spin-1/2 excitations (spinons). In one model the
frustration is static and based on fine tuning of the coupling constants,
whereas in the other it is dynamic and does not require adjusting of the model
parameters. For both models we derive a low-energy effective action which does
not contain any constraints. Though our models admit the standard gauge theory
treatment, we follow an alternative approach based on Abelian and non-Abelian
bosonization. We prove the existence of propagating spin-1/2 excitations
(spinons) and consider in detail certain exactly solvable limits. A qualitative
discussion of the most general case is also presented.Comment: 42 pages, 7 figures, replaced with revised versio