1,373 research outputs found
Uniformization of Deligne-Mumford curves
We compute the fundamental groups of non-singular analytic Deligne-Mumford
curves, classify the simply connected ones, and classify analytic
Deligne-Mumford curves by their uniformization type. As a result, we find an
explicit presentation of an arbitrary Deligne-Mumford curve as a quotient
stack. Along the way, we compute the automorphism 2-groups of weighted
projective stacks . We also discuss connections
with the theory of F-groups, 2-groups, and Bass-Serre theory of graphs of
groups.Comment: 39 pages, 2 figure
The intrinsic normal cone
We suggest a construction of virtual fundamental classes of certain types of
moduli spaces.Comment: LaTeX, Postscript file available at
http://www.math.ubc.ca/people/faculty/behrend/inc.p
Donaldson-Thomas invariants and wall-crossing formulas
Notes from the report at the Fields institute in Toronto. We introduce the
Donaldson-Thomas invariants and describe the wall-crossing formulas for
numerical Donaldson-Thomas invariants.Comment: 18 pages. To appear in the Fields Institute Monograph Serie
transition form factor within Light Front Quark Model
We study the transition form factor of as a
function of the momentum transfer within the light-front quark model
(LFQM). We compare our result with the experimental data by BaBar as well as
other calculations based on the LFQM in the literature. We show that our
predicted form factor fits well with the experimental data, particularly those
at the large region.Comment: 11 pages, 4 figures, accepted for publication in PR
The Boundary Conformal Field Theories of the 2D Ising critical points
We present a new method to identify the Boundary Conformal Field Theories
(BCFTs) describing the critical points of the Ising model on the strip. It
consists in measuring the low-lying excitation energies spectra of its quantum
spin chain for different boundary conditions and then to compare them with
those of the different boundary conformal field theories of the
minimal model.Comment: 7 pages, no figures. Talk given at the XXth International Conference
on Integrable Systems and Quantum Symmetries (ISQS-20). Prague, June 201
On the Classification of Bulk and Boundary Conformal Field Theories
The classification of rational conformal field theories is reconsidered from
the standpoint of boundary conditions. Solving Cardy's equation expressing the
consistency condition on a cylinder is equivalent to finding integer valued
representations of the fusion algebra. A complete solution not only yields the
admissible boundary conditions but also gives valuable information on the bulk
properties.Comment: 7 pages, LaTeX; minor correction
Boundary Conditions in Rational Conformal Field Theories
We develop further the theory of Rational Conformal Field Theories (RCFTs) on
a cylinder with specified boundary conditions emphasizing the role of a triplet
of algebras: the Verlinde, graph fusion and Pasquier algebras. We show that
solving Cardy's equation, expressing consistency of a RCFT on a cylinder, is
equivalent to finding integer valued matrix representations of the Verlinde
algebra. These matrices allow us to naturally associate a graph to each
RCFT such that the conformal boundary conditions are labelled by the nodes of
. This approach is carried to completion for theories leading to
complete sets of conformal boundary conditions, their associated cylinder
partition functions and the -- classification. We also review the
current status for WZW theories. Finally, a systematic generalization
of the formalism of Cardy-Lewellen is developed to allow for multiplicities
arising from more general representations of the Verlinde algebra. We obtain
information on the bulk-boundary coefficients and reproduce the relevant
algebraic structures from the sewing constraints.Comment: 71 pages. Minor changes with respect to 2nd version. Recently
published in Nucl.Phys.B but mistakenly as 1st version. Will be republished
in Nucl.Phys.B as this (3rd) versio
The symplectic Deligne-Mumford stack associated to a stacky polytope
We discuss a symplectic counterpart of the theory of stacky fans. First, we
define a stacky polytope and construct the symplectic Deligne-Mumford stack
associated to the stacky polytope. Then we establish a relation between stacky
polytopes and stacky fans: the stack associated to a stacky polytope is
equivalent to the stack associated to a stacky fan if the stacky fan
corresponds to the stacky polytope.Comment: 20 pages; v2: To appear in Results in Mathematic
Photon-meson transition form factors of light pseudoscalar mesons
The photon-meson transition form factors of light pseudoscalar mesons , , and are systematically calculated in a
light-cone framework, which is applicable as a light-cone quark model at low
and is also physically in accordance with the light-cone pQCD approach
at large . The calculated results agree with the available experimental
data at high energy scale. We also predict the low behaviors of the
photon-meson transition form factors of , and , which are measurable in process via Primakoff
effect at JLab and DESY.Comment: 22 Latex pages, 7 figures, Version to appear in PR
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