arXiv subjects

S. Pacheva

Publications and source records attributed to S. Pacheva.

23 records · Page 2Linked to original sources

arXiv1994

Two-Matrix String Model as Constrained (2+1)-Dimensional Integrable System

We show that the 2-matrix string model corresponds to a coupled system of $2+1$-dimensional KP and modified KP ($\KPm$) integrable equations subject to a specific ``symmetry'' constraint. The latter together with the Miura-Konopelchenko map for $\KPm$ are the continuum incarnation of the matrix string equation. The $\KPm$ Miura and Bäcklund transformations are natural consequences of the underlying lattice structure. The constrained $\KPm$ system is equivalent to a $1+1$-dimensional generalized KP-KdV hierarchy related to graded ${\bf SL(3,1)}$. We provide an explicit representation of this hierarchy, including the associated ${\bf W(2,1)}$-algebra of the second Hamiltonian structure, in terms of free currents.

hep-th↗

arXiv1994

Hamiltonian Structures of the Multi-Boson KP Hierarchies, Abelianization and Lattice Formulation

We present a new form of the multi-boson reduction of KP hierarchy with Lax operator written in terms of boson fields abelianizing the second Hamiltonian structure. This extends the classical Miura transformation and the Kupershmidt-Wilson theorem from the (m)KdV to the KP case. A remarkable relationship is uncovered between the higher Hamiltonian structures and the corresponding Miura transformations of KP hierarchy, on one hand, and the discrete integrable models living on {\em refinements} of the original lattice connected with the underlying multi-matrix models, on the other hand. For the second KP Hamiltonian structure, worked out in details, this amounts to finding a series of representations of the nonlinear $\hWinf$ algebra in terms of arbitrary finite number of canonical pairs of free fields.

hep-th↗

arXiv1993

Construction of KP Hierarchies in Terms of Finite Number of Fields and their Abelianization

The $2M$-boson representations of KP hierarchy are constructed in terms of $M$ mutually independent two-boson KP representations for arbitrary number $M$. Our construction establishes the multi-boson representations of KP hierarchy as consistent Poisson reductions of standard KP hierarchy within the $R$-matrix scheme. As a byproduct we obtain a complete description of any finitely-many-field formulation of KP hierarchy in terms of Darboux coordinates with respect to the first Hamiltonian structure. This results in a series of representations of $\Win1\,$ algebra made out of arbitrary even number of boson fields.

hep-th↗

arXiv1992

R-Matrix Formulation of KP Hierarchies and their Gauge Equivalence

The Adler-Kostant-Symes $R$-bracket scheme is applied to the algebra of pseudo-differential operators to relate the three integrable hierarchies: KP and its two modifications, known as nonstandard integrable models. All three hierarchies are shown to be equivalent and connection is established in the form of a symplectic gauge transformation. This construction results in a new representation of the W-infinity algebras in terms of 4 bosonic fields.

hep-th↗

arXiv1992

Induced $W_\infty$ Gravity as a WZNW Model

We derive the explicit form of the Wess-Zumino quantum effective action of chiral $\Winf$-symmetric system of matter fields coupled to a general chiral $\Winf$-gravity background. It is expressed as a geometric action on a coadjoint orbit of the deformed group of area-preserving diffeomorphisms on cylinder whose underlying Lie algebra is the centrally-extended algebra of symbols of differential operators on the circle. Also, we present a systematic derivation, in terms of symbols, of the "hidden" $SL(\infty;\IR)$ Kac-Moody currents and the associated $SL(\infty;\IR)$ Sugawara form of energy-momentum tensor component $T_{++}$ as a consequence of the $SL(\infty;\IR)$ stationary subgroup of the relevant $\Winf$ coadjoint orbit.

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