1,226 research outputs found
Quantum Knizhnik-Zamolodchikov Equation, Totally Symmetric Self-Complementary Plane Partitions and Alternating Sign Matrices
We present multiresidue formulae for partial sums in the basis of link
patterns of the polynomial solution to the level 1 U_q(\hat sl_2) quantum
Knizhnik--Zamolodchikov equation at generic values of the quantum parameter q.
These allow for rewriting and generalizing a recent conjecture [Di Francesco
'06] connecting the above to generating polynomials for weighted Totally
Symmetric Self-Complementary Plane Partitions. We reduce the corresponding
conjectures to a single integral identity, yet to be proved
The Andrews-Gordon identities and -multinomial coefficients
We prove polynomial boson-fermion identities for the generating function of
the number of partitions of of the form , with
, and . The bosonic side of
the identities involves -deformations of the coefficients of in the
expansion of . A combinatorial interpretation for these
-multinomial coefficients is given using Durfee dissection partitions. The
fermionic side of the polynomial identities arises as the partition function of
a one-dimensional lattice-gas of fermionic particles. In the limit
, our identities reproduce the analytic form of Gordon's
generalization of the Rogers--Ramanujan identities, as found by Andrews. Using
the duality, identities are obtained for branching functions
corresponding to cosets of type of fractional level .Comment: 31 pages, Latex, 9 Postscript figure
Monte Carlo simulation of SU(2) Yang-Mills theory with light gluinos
In a numerical Monte Carlo simulation of SU(2) Yang-Mills theory with light
dynamical gluinos the low energy features of the dynamics as confinement and
bound state mass spectrum are investigated. The motivation is supersymmetry at
vanishing gluino mass. The performance of the applied two-step multi-bosonic
dynamical fermion algorithm is discussed.Comment: latex, 48 pages, 16 figures with epsfi
Orthogonal Polynomials from Hermitian Matrices II
This is the second part of the project `unified theory of classical
orthogonal polynomials of a discrete variable derived from the eigenvalue
problems of hermitian matrices.' In a previous paper, orthogonal polynomials
having Jackson integral measures were not included, since such measures cannot
be obtained from single infinite dimensional hermitian matrices. Here we show
that Jackson integral measures for the polynomials of the big -Jacobi family
are the consequence of the recovery of self-adjointness of the unbounded Jacobi
matrices governing the difference equations of these polynomials. The recovery
of self-adjointness is achieved in an extended Hilbert space on which
a direct sum of two unbounded Jacobi matrices acts as a Hamiltonian or a
difference Schr\"odinger operator for an infinite dimensional eigenvalue
problem. The polynomial appearing in the upper/lower end of Jackson integral
constitutes the eigenvector of each of the two unbounded Jacobi matrix of the
direct sum. We also point out that the orthogonal vectors involving the
-Meixner (-Charlier) polynomials do not form a complete basis of the
Hilbert space, based on the fact that the dual -Meixner polynomials
introduced in a previous paper fail to satisfy the orthogonality relation. The
complete set of eigenvectors involving the -Meixner polynomials is obtained
by constructing the duals of the dual -Meixner polynomials which require the
two component Hamiltonian formulation. An alternative solution method based on
the closure relation, the Heisenberg operator solution, is applied to the
polynomials of the big -Jacobi family and their duals and -Meixner
(-Charlier) polynomials.Comment: 65 pages. Comments, references and table of contents are added. To
appear in J.Math.Phy
Solutions of a two-particle interacting quantum walk
We study the solutions of the interacting Fermionic cellular automaton
introduced in Ref. [Phys Rev A 97, 032132 (2018)]. The automaton is the
analogue of the Thirring model with both space and time discrete. We present a
derivation of the two-particles solutions of the automaton, which exploits the
symmetries of the evolution operator. In the two-particles sector, the
evolution operator is given by the sequence of two steps, the first one
corresponding to a unitary interaction activated by two-particle excitation at
the same site, and the second one to two independent one-dimensional Dirac
quantum walks. The interaction step can be regarded as the discrete-time
version of the interacting term of some Hamiltonian integrable system, such as
the Hubbard or the Thirring model. The present automaton exhibits scattering
solutions with nontrivial momentum transfer, jumping between different regions
of the Brillouin zone that can be interpreted as Fermion-doubled particles, in
stark contrast with the customary momentum-exchange of the one dimensional
Hamiltonian systems. A further difference compared to the Hamiltonian model is
that there exist bound states for every value of the total momentum, and even
for vanishing coupling constant. As a complement to the analytical derivations
we show numerical simulations of the interacting evolution.Comment: 16 pages, 6 figure
Morse theory on spaces of braids and Lagrangian dynamics
In the first half of the paper we construct a Morse-type theory on certain
spaces of braid diagrams. We define a topological invariant of closed positive
braids which is correlated with the existence of invariant sets of parabolic
flows defined on discretized braid spaces. Parabolic flows, a type of
one-dimensional lattice dynamics, evolve singular braid diagrams in such a way
as to decrease their topological complexity; algebraic lengths decrease
monotonically. This topological invariant is derived from a Morse-Conley
homotopy index and provides a gloablization of `lap number' techniques used in
scalar parabolic PDEs.
In the second half of the paper we apply this technology to second order
Lagrangians via a discrete formulation of the variational problem. This
culminates in a very general forcing theorem for the existence of infinitely
many braid classes of closed orbits.Comment: Revised version: numerous changes in exposition. Slight modification
of two proofs and one definition; 55 pages, 20 figure
Local height probabilities in a composite Andrews-Baxter-Forrester model
We study the local height probabilities in a composite height model, derived
from the restricted solid-on-solid model introduced by Andrews, Baxter and
Forrester, and their connection with conformal field theory characters. The
obtained conformal field theories also describe the critical behavior of the
model at two different critical points. In addition, at criticality, the model
is equivalent to a one-dimensional chain of anyons, subject to competing two-
and three-body interactions. The anyonic-chain interpretation provided the
original motivation to introduce the composite height model, and by obtaining
the critical behaviour of the composite height model, the critical behaviour of
the anyonic chains is established as well. Depending on the overall sign of the
hamiltonian, this critical behaviour is described by a diagonal coset-model,
generalizing the minimal models for one sign, and by Fateev-Zamolodchikov
parafermions for the other.Comment: 34 pages, 5 figures; v2: expanded introduction, references added and
other minor change
Revisiting the combinatorics of the 2D Ising model
We provide a concise exposition with original proofs of combinatorial
formulas for the 2D Ising model partition function, multi-point fermionic
observables, spin and energy density correlations, for general graphs and
interaction constants, using the language of Kac-Ward matrices. We also give a
brief account of the relations between various alternative formalisms which
have been used in the combinatorial study of the planar Ising model: dimers and
Grassmann variables, spin and disorder operators, and, more recently,
s-holomorphic observables. In addition, we point out that these formulas can be
extended to the double-Ising model, defined as a pointwise product of two Ising
spin configurations on the same discrete domain, coupled along the boundary.Comment: Minor change in the notation (definition of eta). 55 pages, 4 figure
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