9,604 research outputs found
Polynomial Fusion Rings of Logarithmic Minimal Models
We identify quotient polynomial rings isomorphic to the recently found
fundamental fusion algebras of logarithmic minimal models.Comment: 18 page
Planar maps as labeled mobiles
We extend Schaeffer's bijection between rooted quadrangulations and
well-labeled trees to the general case of Eulerian planar maps with prescribed
face valences, to obtain a bijection with a new class of labeled trees, which
we call mobiles. Our bijection covers all the classes of maps previously
enumerated by either the two-matrix model used by physicists or by the
bijection with blossom trees used by combinatorists. Our bijection reduces the
enumeration of maps to that, much simpler, of mobiles and moreover keeps track
of the geodesic distance within the initial maps via the mobiles' labels.
Generating functions for mobiles are shown to obey systems of algebraic
recursion relations.Comment: 31 pages, 17 figures, tex, lanlmac, epsf; improved tex
Statistics of planar graphs viewed from a vertex: A study via labeled trees
We study the statistics of edges and vertices in the vicinity of a reference
vertex (origin) within random planar quadrangulations and Eulerian
triangulations. Exact generating functions are obtained for theses graphs with
fixed numbers of edges and vertices at given geodesic distances from the
origin. Our analysis relies on bijections with labeled trees, in which the
labels encode the information on the geodesic distance from the origin. In the
case of infinitely large graphs, we give in particular explicit formulas for
the probabilities that the origin have given numbers of neighboring edges
and/or vertices, as well as explicit values for the corresponding moments.Comment: 36 pages, 15 figures, tex, harvmac, eps
Critical and Multicritical Semi-Random (1+d)-Dimensional Lattices and Hard Objects in d Dimensions
We investigate models of (1+d)-D Lorentzian semi-random lattices with one
random (space-like) direction and d regular (time-like) ones. We prove a
general inversion formula expressing the partition function of these models as
the inverse of that of hard objects in d dimensions. This allows for an exact
solution of a variety of new models including critical and multicritical
generalized (1+1)-D Lorentzian surfaces, with fractal dimensions ,
k=1,2,3,..., as well as a new model of (1+2)-D critical tetrahedral complexes,
with fractal dimension . Critical exponents and universal scaling
functions follow from this solution. We finally establish a general connection
between (1+d)-D Lorentzian lattices and directed-site lattice animals in (1+d)
dimensions.Comment: 44 pages, 15 figures, tex, harvmac, epsf, references adde
Open boundary Quantum Knizhnik-Zamolodchikov equation and the weighted enumeration of Plane Partitions with symmetries
We propose new conjectures relating sum rules for the polynomial solution of
the qKZ equation with open (reflecting) boundaries as a function of the quantum
parameter and the -enumeration of Plane Partitions with specific
symmetries, with . We also find a conjectural relation \`a la
Razumov-Stroganov between the limit of the qKZ solution and refined
numbers of Totally Symmetric Self Complementary Plane Partitions.Comment: 27 pages, uses lanlmac, epsf and hyperbasics, minor revision
The Perceived Impact of the In-Trust Agreements on CGIAR Germplasm Availability: An Assessment of Bioversity International's Institutional Activities
This study assesses the generation and consequences of the In-Trust Agreements (ITAs) that established the legal status of the CGIAR germplasm as freely available for the benefit of humanity under the auspices of FAO. The analysis looks at the history of the ITAs and focuses on the role of Bioversity International in research and other activities in influencing, facilitating and enabling the ITA negotiations. Results confirm the central role of Bioversity and policy research in the negotiations process. Concepts developed during the ITA negotiations contributed toward subsequent multilateral negotiations that eventually culminated in the International Treaty on Plant Genetic Resources
Entanglement Entropy of the Low-Lying Excited States and Critical Properties of an Exactly Solvable Two-Leg Spin Ladder with Three-Spin Interactions
In this work, we investigate an exactly solvable two-leg spin ladder with
three-spin interactions. We obtain analytically the finite-size corrections of
the low-lying energies and determine the central charge as well as the scaling
dimensions. The model considered in this work has the same universality class
of critical behavior of the XX chain with central charge c=1. By using the
correlation matrix method, we also study the finite-size corrections of the
Renyi entropy of the ground state and of the excited states. Our results are in
agreement with the predictions of the conformal field theory.Comment: 10 pages, 6 figures, 2 table
Infinite matrix product states, Conformal Field Theory and the Haldane-Shastry model
We generalize the Matrix Product States method using the chiral vertex
operators of Conformal Field Theory and apply it to study the ground states of
the XXZ spin chain, the J1-J2 model and random Heisenberg models. We compute
the overlap with the exact wave functions, spin-spin correlators and the Renyi
entropy, showing that critical systems can be described by this method. For
rotational invariant ansatzs we construct an inhomogenous extension of the
Haldane-Shastry model with long range exchange interactions.Comment: 5 pages, 4 figures, 1 reference adde
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