3,149 research outputs found

### On Models with Inverse-Square Exchange

A one-dimensional quantum N-body system of either fermions or bosons with
$SU(n)$ colors interacting via inverse-square exchange is presented in this
article. A class of eigenstates of both the continuum and lattice version of
the model Hamiltonians is constructed in terms of the Jastrow-product type wave
function. The class of states we construct in this paper corresponds to the
ground state and the low energy excitations of the model that can be described
by the effective harmonic fluid Hamiltonian. By expanding the energy about the
ground state we find the harmonic fluid parameters (i.e. the charge, spin
velocities, etc.), explicitly. The correlation exponent and the compressibility
of are also found. As expected the general harmonic relation(i.e.
$v_S=(v_Nv_J)^{1/2}$) is satisfied among the charge and spin velocities.Comment: 26 page

### Exact calculation of the ground-state dynamical spin correlation function of a S=1/2 antiferromagnetic Heisenberg chain with free spinons

We calculate the exact dynamical magnetic structure factor S(Q,E) in the
ground state of a one-dimensional S=1/2 antiferromagnet with gapless free S=1/2
spinon excitations, the Haldane-Shastry model with inverse-square exchange,
which is in the same low-energy universality class as Bethe's nearest-neighbor
exchange model. Only two-spinon excited states contribute, and S(Q,E) is found
to be a very simple integral over these states.Comment: 11 pages, LaTeX, RevTeX 3.0, cond-mat/930903

### Conformal Field Theory on the Fermi Surface

The Fermi surface may be usefully viewed as a collection of 1+1 dimensional
chiral conformal field theories. This approach permits straightforward
calculation of many anomalous ground state properties of the Fermi gas
including entanglement entropy and number fluctuations. The 1+1 dimensional
picture also generalizes to finite temperature and the presence of
interactions. Finally, I argue that the low energy entanglement structure of
Fermi liquid theory is universal, depending only on the geometry of the
interacting Fermi surface.Comment: 4 pages + references, 2 figure

### Laughlin State on Stretched and Squeezed Cylinders and Edge Excitations in Quantum Hall Effect

We study the Laughlin wave function on the cylinder. We find it only
describes an incompressible fluid when the two lengths of the cylinder are
comparable. As the radius is made smaller at fixed area, we observe a
continuous transition to the charge density wave Tao-Thouless state. We also
present some exact properties of the wave function in its polynomial form. We
then study the edge excitations of the quantum Hall incompressible fluid
modeled by the Laughlin wave function. The exponent describing the fluctuation
of the edge predicted by recent theories is shown to be identical with
numerical calculations. In particular, for $\nu=1/3$, we obtain the occupation
amplitudes of edge state $n(k)$ for 4-10 electron size systems. When plotted as
a function of the scaled wave vector they become essentially free of
finite-size effects. The resulting curve obtains a very good agreement with the
appropriate infinite-size Calogero-Sutherland model occupation numbers.
Finally, we numerically obtain $n(k)$ of the edge excitations for some pairing
states which may be relevant to the $\nu=5/2$ incompressible Hall state.Comment: 25 pages revtex, 9 uuencoded figures, submitted separately, also
available from first author. CSULA-94-1

### Two-dimensional anyons and the temperature dependence of commutator anomalies

The temperature dependence of commutator anomalies is discussed on the
explicit example of particular (anyonic) field operators in two dimensions. The
correlation functions obtained show that effects of the non-zero temperature
might manifest themselves not only globally but also locally.Comment: 11 pages, LaTe

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