1,518 research outputs found
Threshold Singularities in the One Dimensional Hubbard Model
We consider excitations with the quantum numbers of a hole in the one
dimensional Hubbard model below half-filling. We calculate the finite-size
corrections to the energy. The results are then used to determine threshold
singularities in the single-particle Green's function for commensurate
fillings. We present the analogous results for the Yang-Gaudin model (electron
gas with delta-function interactions).Comment: 26 pages, 12 figures version to appear in Phys Rev
Dynamics in the Ising field theory after a quantum quench
We study the real-time dynamics of the order parameter . Our main result is the development of
a method for treating divergences associated with working directly in the field
theory limit. We recover the scaling limit of the corresponding result by
Calabrese et al. [Phys. Rev. Lett. \textbf{106}, 227203 (2011)], which was
obtained for the lattice model. Our formalism generalizes to integrable quantum
quenches in other integrable models
Determinant formula for the six-vertex model with reflecting end
Using the Quantum Inverse Scattering Method for the XXZ model with open
boundary conditions, we obtained the determinant formula for the six vertex
model with reflecting end.Comment: 10 page
Relationship between single-particle excitation and spin excitation at the Mott Transition
An intuitive interpretation of the relationship between the dispersion
relation of the single-particle excitation in a metal and that of the spin
excitation in a Mott insulator is presented, based on the results for the one-
and two-dimensional Hubbard models obtained by using the Bethe ansatz,
dynamical density-matrix renormalization group method, and cluster perturbation
theory. The dispersion relation of the spin excitation in the Mott insulator is
naturally constructed from that of the single-particle excitation in the
zero-doping limit in both one- and two-dimensional Hubbard models, which allows
us to interpret the doping-induced states as the states that lose charge
character toward the Mott transition. The characteristic feature of the Mott
transition is contrasted with the feature of a Fermi liquid and that of the
transition between a band insulator and a metal.Comment: 6 pages, 2 figures, to appear in JPS Conf. Pro
Dynamical Spin Response of Doped Two-Leg Hubbard-like Ladders
We study the dynamical spin response of doped two-leg Hubbard-like ladders in
the framework of a low-energy effective field theory description given by the
SO(6) Gross Neveu model. Using the integrability of the SO(6) Gross-Neveu
model, we derive the low energy dynamical magnetic susceptibility. The
susceptibility is characterized by an incommensurate coherent mode near
and by broad two excitation scattering continua at other
-points. In our computation we are able to estimate the relative weights of
these contributions.
All calculations are performed using form-factor expansions which yield exact
low energy results in the context of the SO(6) Gross-Neveu model. To employ
this expansion, a number of hitherto undetermined form factors were computed.
To do so, we developed a general approach for the computation of matrix
elements of semi-local SO(6) Gross-Neveu operators. While our computation takes
place in the context of SO(6) Gross-Neveu, we also consider the effects of
perturbations away from an SO(6) symmetric model, showing that small
perturbations at best quantitatively change the physics.Comment: 32 pages and 7 figure
Dynamical Magnetic Susceptibilities in Cu Benzoate
Recent experiments on the quasi 1-D antiferromagnet Cu Benzoate revealed a
magentic field induced gap coexisting with (ferro)magnetic order. A theory
explaining these findings has been proposed by Oshikawa and Affleck. In the
present work we discuss consequences of this theory for inelastic neutron
scattering experiments by calculating the dynamical magnetic susceptibilities
close to the antiferromagnetic wave vector by the formfactor method.Comment: 6 pages of revtex, 9 figures, extended comparison with experimen
Algebraic properties of an integrable t-J model with impurities
We investigate the algebraic structure of a recently proposed integrable
model with impurities. Three forms of the Bethe ansatz equations are
presented corresponding to the three choices for the grading. We prove that the
Bethe ansatz states are highest weight vectors of the underlying
supersymmetry algebra. By acting with the generators we construct a
complete set of states for the model.Comment: 20 pages, LaTe
Spectrum of Low-Lying Excitations in a Supersymmetric Extended Hubbard Model
We continue the study of the -supersymmetric extension of the Hubbard
model in one dimension. We determine the excitation spectrum at zero
temperature even in the sectors where the ground states are
-descendants of Bethe states. The excitations include spinons, holons,
electrons, localons (local electrons pairs, moving coherently through the
lattice) and their bound states. The spectra are found to be very different for
repulsive and attractive on-site interaction. We also study the thermodynamics
of the model.Comment: 37 pages, uuencoded compressed postscript fil
Applications of Massive Integrable Quantum Field Theories to Problems in Condensed Matter Physics
We review applications of the sine-Gordon model, the O(3) non-linear sigma
model, the U(1) Thirring model, and the O(N) Gross--Neveu model to quasi
one-dimensional quantum magnets, Mott insulators, and carbon nanotubes. We
focus upon the determination of dynamical response functions for these
problems. These quantities are computed by means of form factor expansions of
quantum correlation functions in integrable quantum field theories. This
approach is reviewed here in some detail.Comment: 150 pages, 35 figures, published in the I. Kogan Memorial Volume by
World Scientifi
- …