28 research outputs found
A convenient criterion under which Z_2-graded operators are Hamiltonian
We formulate a simple and convenient criterion under which skew-adjoint
Z_2-graded total differential operators are Hamiltonian, provided that their
images are closed under commutation in the Lie algebras of evolutionary vector
fields on the infinite jet spaces for vector bundles over smooth manifolds.Comment: J.Phys.Conf.Ser.: Mathematical and Physical Aspects of Symmetry.
Proc. 28th Int. colloq. on group-theoretical methods in Physics (July 26-30,
2010; Newcastle-upon-Tyne, UK), 6 pages (in press
The graded Jacobi algebras and (co)homology
Jacobi algebroids (i.e. `Jacobi versions' of Lie algebroids) are studied in
the context of graded Jacobi brackets on graded commutative algebras. This
unifies varios concepts of graded Lie structures in geometry and physics. A
method of describing such structures by classical Lie algebroids via certain
gauging (in the spirit of E.Witten's gauging of exterior derivative) is
developed. One constructs a corresponding Cartan differential calculus (graded
commutative one) in a natural manner. This, in turn, gives canonical generating
operators for triangular Jacobi algebroids. One gets, in particular, the
Lichnerowicz-Jacobi homology operators associated with classical Jacobi
structures. Courant-Jacobi brackets are obtained in a similar way and use to
define an abstract notion of a Courant-Jacobi algebroid and Dirac-Jacobi
structure. All this offers a new flavour in understanding the
Batalin-Vilkovisky formalism.Comment: 20 pages, a few typos corrected; final version to be published in J.
Phys. A: Math. Ge
Classical field theory. Advanced mathematical formulation
In contrast with QFT, classical field theory can be formulated in strict
mathematical terms of fibre bundles, graded manifolds and jet manifolds. Second
Noether theorems provide BRST extension of this classical field theory by means
of ghosts and antifields for the purpose of its quantization.Comment: 30 p
The BV-algebra structure of W_3 cohomology
We summarize some recent results obtained in collaboration with J. McCarthy
on the spectrum of physical states in gravity coupled to matter. We
show that the space of physical states, defined as a semi-infinite (or BRST)
cohomology of the algebra, carries the structure of a BV-algebra. This
BV-algebra has a quotient which is isomorphic to the BV-algebra of polyvector
fields on the base affine space of . Details have appeared elsewhere.
[Published in the proceedings of "Gursey Memorial Conference I: Strings and
Symmetries," Istanbul, June 1994, eds. G. Aktas et al., Lect. Notes in Phys.
447, (Springer Verlag, Berlin, 1995)]Comment: 8 pages; uses macros tables.tex and amssym.def (version 2.1 or later
Symmetries of Differential Equations via Cartan's Method of Equivalence
We formulate a method of computing invariant 1-forms and structure equations
of symmetry pseudo-groups of differential equations based on Cartan's method of
equivalence and the moving coframe method introduced by Fels and Olver. Our
apparoach does not require a preliminary computation of infinitesimal defining
systems, their analysis and integration, and uses differentiation and linear
algebra operations only. Examples of its applications are given.Comment: 15 pages, LaTeX 2.0
Why nonlocal recursion operators produce local symmetries: new results and applications
It is well known that integrable hierarchies in (1+1) dimensions are local
while the recursion operators that generate them usually contain nonlocal
terms. We resolve this apparent discrepancy by providing simple and universal
sufficient conditions for a (nonlocal) recursion operator in (1+1) dimensions
to generate a hierarchy of local symmetries. These conditions are satisfied by
virtually all known today recursion operators and are much easier to verify
than those found in earlier work.
We also give explicit formulas for the nonlocal parts of higher recursion
operators, Poisson and symplectic structures of integrable systems in (1+1)
dimensions.
Using these two results we prove, under some natural assumptions, the
Maltsev--Novikov conjecture stating that higher Hamiltonian, symplectic and
recursion operators of integrable systems in (1+1) dimensions are weakly
nonlocal, i.e., the coefficients of these operators are local and these
operators contain at most one integration operator in each term.Comment: 10 pages, LaTeX 2e, final versio
Scalar second order evolution equations possessing an irreducible sl-valued zero curvature representation
We find all scalar second order evolution equations possessing an
sl-valued zero curvature representation that is not reducible to a proper
subalgebra of sl. None of these zero-curvature representations admits a
parameter.Comment: 10 pages, requires nath.st
The Robinson-Trautman Type III Prolongation Structure Contains K
The minimal prolongation structure for the Robinson-Trautman equations of
Petrov type III is shown to always include the infinite-dimensional,
contragredient algebra, K, which is of infinite growth. Knowledge of
faithful representations of this algebra would allow the determination of
B\"acklund transformations to evolve new solutions.Comment: 20 pages, plain TeX, no figures, submitted to Commun. Math. Phy
On the relation between standard and -symmetries for PDEs
We give a geometrical interpretation of the notion of -prolongations of
vector fields and of the related concept of -symmetry for partial
differential equations (extending to PDEs the notion of -symmetry for
ODEs). We give in particular a result concerning the relationship between
-symmetries and standard exact symmetries. The notion is also extended to
the case of conditional and partial symmetries, and we analyze the relation
between local -symmetries and nonlocal standard symmetries.Comment: 25 pages, no figures, latex. to be published in J. Phys.
Homological evolutionary vector fields in Korteweg-de Vries, Liouville, Maxwell, and several other models
We review the construction of homological evolutionary vector fields on
infinite jet spaces and partial differential equations. We describe the
applications of this concept in three tightly inter-related domains: the
variational Poisson formalism (e.g., for equations of Korteweg-de Vries type),
geometry of Liouville-type hyperbolic systems (including the 2D Toda chains),
and Euler-Lagrange gauge theories (such as the Yang-Mills theories, gravity, or
the Poisson sigma-models). Also, we formulate several open problems.Comment: Proc. 7th International Workshop "Quantum Theory and Symmetries-7"
(August 7-13, 2011; CVUT Prague, Czech Republic), 20 page