214 research outputs found
Sigma-models having supermanifolds as target spaces
We study a topological sigma-model (-model) in the case when the target
space is an ()-dimensional supermanifold. We prove under certain
conditions that such a model is equivalent to an -model having an
()-dimensional manifold as a target space. We use this result to prove
that in the case when the target space of -model is a complete intersection
in a toric manifold, this -model is equivalent to an -model having a
toric supermanifold as a target space.Comment: 6 pages,late
Hamiltonian Monodromy Via Picard-lefschetz Theory
Le texte intégral associé à ce dépÎt est la version initiale du preprint de 2001.International audienceIn this paper, we investigate the "Hamiltonian'' monodromy of the fibration in Liouville tori of certain integrable systems via (real) algebraic geometry. Using Picard-Lefschetz theory in a relative Prym variety, we determine the Hamiltonian monodromy of the "geodesic flow on ''. Using a relative generalized Jacobian, we prove that the Hamiltonian monodromy of the spherical pendulum can also be obtained by Picard-Lefschetz formula
A combinatorial formula for homogeneous moments
We establish a combinatorial formula for homogeneous moments and give some
examples where it can be put to use. An application to the statistical
mechanics of interacting gauged vortices is discussed.Comment: 8 pages, LaTe
The geometry of antiferromagnetic spin chains
We construct spin chains that describe relativistic sigma-models in the
continuum limit, using symplectic geometry as a main tool. The target space can
be an arbitrary complex flag manifold, and we find universal expressions for
the metric and theta-term.Comment: 31 pages, 3 figure
Cohomology of toric line bundles via simplicial Alexander duality
We give a rigorous mathematical proof for the validity of the toric sheaf
cohomology algorithm conjectured in the recent paper by R. Blumenhagen, B.
Jurke, T. Rahn, and H. Roschy (arXiv:1003.5217). We actually prove not only the
original algorithm but also a speed-up version of it. Our proof is independent
from (in fact appeared earlier on the arXiv than) the proof by H. Roschy and T.
Rahn (arXiv:1006.2392), and has several advantages such as being shorter and
cleaner and can also settle the additional conjecture on "Serre duality for
Betti numbers" which was raised but unresolved in arXiv:1006.2392.Comment: 9 pages. Theorem 1.1 and Corollary 1.2 improved; Abstract and
Introduction modified; References updated. To appear in Journal of
Mathematical Physic
The frequency map for billiards inside ellipsoids
The billiard motion inside an ellipsoid Q \subset \Rset^{n+1} is completely
integrable. Its phase space is a symplectic manifold of dimension , which
is mostly foliated with Liouville tori of dimension . The motion on each
Liouville torus becomes just a parallel translation with some frequency
that varies with the torus. Besides, any billiard trajectory inside
is tangent to caustics , so the
caustic parameters are integrals of the
billiard map. The frequency map is a key tool to
understand the structure of periodic billiard trajectories. In principle, it is
well-defined only for nonsingular values of the caustic parameters. We present
four conjectures, fully supported by numerical experiments. The last one gives
rise to some lower bounds on the periods. These bounds only depend on the type
of the caustics. We describe the geometric meaning, domain, and range of
. The map can be continuously extended to singular values of
the caustic parameters, although it becomes "exponentially sharp" at some of
them. Finally, we study triaxial ellipsoids of \Rset^3. We compute
numerically the bifurcation curves in the parameter space on which the
Liouville tori with a fixed frequency disappear. We determine which ellipsoids
have more periodic trajectories. We check that the previous lower bounds on the
periods are optimal, by displaying periodic trajectories with periods four,
five, and six whose caustics have the right types. We also give some new
insights for ellipses of \Rset^2.Comment: 50 pages, 13 figure
Special lagrangian fibrations on flag variety
One constructs lagrangian fibrations on the flag variety and proves
that the fibrations are special.Comment: 19 page
Searching for K3 Fibrations
We present two methods for studying fibrations of Calabi-Yau manifolds
embedded in toric varieties described by single weight systems. We analyse
184,026 such spaces and identify among them 124,701 which are K3 fibrations. As
some of the weights give rise to two or three distinct types of fibrations, the
total number we find is 167,406. With our methods one can also study elliptic
fibrations of 3-folds and K3 surfaces. We also calculate the Hodge numbers of
the 3-folds obtaining more than three times as many as were previously known.Comment: 21 pages, LaTeX2e, 4 eps figures, uses packages
amssymb,latexsym,cite,epi
New Examples of Systems of the Kowalevski Type
A new examples of integrable dynamical systems are constructed. An
integration procedure leading to genus two theta-functions is presented. It is
based on a recent notion of discriminantly separable polynomials. They have
appeared in a recent reconsideration of the celebrated Kowalevski top, and
their role here is analogue to the situation with the classical Kowalevski
integration procedure.Comment: 17 page
On the spectra of the quantized action-variables of the compactified Ruijsenaars-Schneider system
A simple derivation of the spectra of the action-variables of the quantized
compactified Ruijsenaars-Schneider system is presented. The spectra are
obtained by combining Kahler quantization with the identification of the
classical action-variables as a standard toric moment map on the complex
projective space. The result is consistent with the Schrodinger quantization of
the system worked out previously by van Diejen and Vinet.Comment: Based on talk at the workshop CQIS-2011 (Protvino, Russia, January
2011), 12 page
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