796 research outputs found
The Form Factor Program: a Review and New Results - the Nested SU(N) Off-Shell Bethe Ansatz
The purpose of the ''bootstrap program'' for integrable quantum field
theories in 1+1 dimensions is to construct explicitly a model in terms of its
Wightman functions. In this article, this program is mainly illustrated in
terms of the sinh-Gordon model and the SU(N) Gross-Neveu model. The nested
off-shell Bethe ansatz for an SU(N) factorizing S-matrix is constructed. We
review some previous results on sinh-Gordon form factors and the quantum
operator field equation. The problem of how to sum over intermediate states is
considered in the short distance limit of the two point Wightman function for
the sinh-Gordon model.Comment: This is a contribution to the Proc. of the O'Raifeartaigh Symposium
on Non-Perturbative and Symmetry Methods in Field Theory (June 2006,
Budapest, Hungary), published in SIGMA (Symmetry, Integrability and Geometry:
Methods and Applications) at http://www.emis.de/journals/SIGMA
Bethe ansatz solution of a closed spin 1 XXZ Heisenberg chain with quantum algebra symmetry
A quantum algebra invariant integrable closed spin 1 chain is introduced and
analysed in detail. The Bethe ansatz equations as well as the energy
eigenvalues of the model are obtained. The highest weight property of the Bethe
vectors with respect to U_q(sl(2)) is proved.Comment: 13 pages, LaTeX, to appear in J. Math. Phy
Confined step-flow growth of Cu intercalated between graphene and a Ru(0001) surface
By comparing the growth of Cu thin films on bare and graphene-covered
Ru(0001) surfaces, we demonstrate the role of graphene as a surfactant allowing
the formation of flat Cu films. Low-energy electron microscopy, X-ray
photoemission electron microscopy and X-ray absorption spectroscopy reveal that
depositing Cu at 580 K leads to distinct behaviors on both types of surfaces.
On bare Ru, a Stranski-Krastanov growth is observed, with first the formation
of an atomically flat and monolayer-thick wetting layer, followed by the
nucleation of three-dimensional islands. In sharp contrast, when Cu is
deposited on a graphene-covered Ru surface under the very same conditions, Cu
intercalates below graphene and grows in a step-flow manner: atomically-high
growth fronts of intercalated Cu form at the graphene edges, and extend towards
the center of the flakes. Our findings suggest potential routes in metal
heteroepitaxy for the control of thin film morphology.Comment: 9 pages, 4 figure
Bethe Ansatz and exact form factors of the O (N) Gross Neveu-model
We apply previous results on the O (N) Bethe Ansatz [1-3] to construct a
general form factor formula for the O (N) Gross-Neveu model. We examine this
formula for several operators, such as the energy momentum, the spin-field and
the current. We also compare these results with the 1/N expansion of this
model and obtain full agreement. We discuss bound state form factors, in
particular for the three particle form factor of the field. In addition for
the two particle case we prove a recursion relation for the K-functions of the
higher level Bethe Ansatz
Bethe ansatz and exact form factors of the O(6) Gross Neveu-model
The isomorphism SU(4)\simeq O(6) is used to construct the form factors of the
O(6) Gross–Neveu model as bound state form factors of the SU(4) chiral
Gross–Neveu model. This technique is generalized and is then applied to use
the O(6) as the starting point of the nesting procedure to obtain the O(N)
form factors for general even N
Exact form factors of the O(N) σ-model
A general form factor formula for the O(N ) σ-model is constructed and applied
to several operators. The large N limits of these form factors are computed
and compared with the 1/N expansion of the O(N ) σ-model in terms of Feynman
graphs and full agreement is found. In particular, O(3) and O(4) form factors
are discussed. For the O(3) σ-model several low particle form factors are
calculated explicitly
- …