First order Hamiltonian operators of differential-geometric type were introduced by Dubrovin and Novikov in 1983, and thoroughly investigated by Mokhov. In 2D, they are generated by a pair of compatible flat metrics g and g~ which satisfy a set of additional constraints coming from the skew-symmetry condition and the Jacobi identity. We demonstrate that these constraints are equivalent to the requirement that g~ is a linear Killing tensor of g with zero Nijenhuis torsion. This allowed us to obtain a complete classification of n-component operators with n ≤ 4 (for n = 1, 2 this was done before). For 2D operators the Darboux theorem does not hold: the operator may not be reducible to constant coefficient form. All interesting (non-constant) examples correspond to the case when the flat pencil g, g~ is not semisimple, that is, the affinor g~g-1 has non-trivial Jordan block structure. In the case of a direct sum of Jordan blocks with distinct eigenvalues, we obtain a complete classification of Hamiltonian operators for any number of components n, revealing a remarkable correspondence with the class of trivial Frobenius manifolds modelled on H*(CPn-1)

Ferapontov, E., Lorenzoni, P., Savoldi, A. (2015). Hamiltonian Operators of Dubrovin-Novikov Type in 2D. LETTERS IN MATHEMATICAL PHYSICS, 105(3), 341-377 [10.1007/s11005-014-0738-6].

Hamiltonian Operators of Dubrovin-Novikov Type in 2D

LORENZONI, PAOLO
;
2015

Abstract

First order Hamiltonian operators of differential-geometric type were introduced by Dubrovin and Novikov in 1983, and thoroughly investigated by Mokhov. In 2D, they are generated by a pair of compatible flat metrics g and g~ which satisfy a set of additional constraints coming from the skew-symmetry condition and the Jacobi identity. We demonstrate that these constraints are equivalent to the requirement that g~ is a linear Killing tensor of g with zero Nijenhuis torsion. This allowed us to obtain a complete classification of n-component operators with n ≤ 4 (for n = 1, 2 this was done before). For 2D operators the Darboux theorem does not hold: the operator may not be reducible to constant coefficient form. All interesting (non-constant) examples correspond to the case when the flat pencil g, g~ is not semisimple, that is, the affinor g~g-1 has non-trivial Jordan block structure. In the case of a direct sum of Jordan blocks with distinct eigenvalues, we obtain a complete classification of Hamiltonian operators for any number of components n, revealing a remarkable correspondence with the class of trivial Frobenius manifolds modelled on H*(CPn-1)
Articolo in rivista - Articolo scientifico
37K05; 37K10; 37K25; 53D45; Mathematical Physics; Statistical and Nonlinear Physics
English
9-dic-2014
2015
105
3
341
377
none
Ferapontov, E., Lorenzoni, P., Savoldi, A. (2015). Hamiltonian Operators of Dubrovin-Novikov Type in 2D. LETTERS IN MATHEMATICAL PHYSICS, 105(3), 341-377 [10.1007/s11005-014-0738-6].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/101294
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