Abstract
We consider modifications of the nonlinear Schrödinger model (NLS) to look at the recently introduced concept of quasi-integrability. We show that such models possess an infinite number of quasi-conserved charges which present intriguing properties in relation to very specific space-time parity transformations. For the case of two-soliton solutions where the fields are eigenstates of this parity, those charges are asymptotically conserved in the scattering process of the solitons. Even though the charges vary in time their values in the far past and the far future are the same. Such results are obtained through analytical and numerical methods, and employ adaptations of algebraic techniques used in integrable field theories. Our findings may have important consequences on the applications of these models in several areas of non-linear science. We make a detailed numerical study of the modified NLS potential of the form V ~ (|ψ|2)2+ε, with ε being a perturbation parameter. We perform numerical simulations of the scattering of solitons for this model and find a good agreement with the results predicted by the analytical considerations. Our paper shows that the quasi-integrability concepts recently proposed in the context of modifications of the sine-Gordon model remain valid for perturbations of the NLS model.
Similar content being viewed by others
References
N.J. Zabusky and M.D. Kruskal, Interaction of ‘solitons’ in a collisionless plasma and the recurrence of initial states, Phys. Rev. Lett. 15 (1965) 240 [INSPIRE].
E. Fermi, J.R. Pasta and S. Ulam, Studies of non linear problems, Los Alamos Scientific Laboratory Report, Document LA-1940 (1955), unpublished.
P.D. Lax, Integrals of nonlinear equations of evolution and solitary waves, Commun. Pure Appl. Math. 21 (1968) 467 [INSPIRE].
V.E. Zakharov and A.B. Shabat, Exact theory of two-dimensional selffocusing and one-dimensional selfmodulation of waves in nonlinear media, Zh. Exp. Teor. Fiz. 61 (1971) 118 [Sov. Phys. JETP 34 (1972) 62] [INSPIRE].
L.D. Faddeev and L.A. Takhtajan, Hamiltonian methods in the theory of solitons, Springer Series in Soviet Mathematics, Springer, Berlin Germany (1987) [INSPIRE].
O. Babelon, D. Bernard and M. Talon, Introduction to classical integrable systems, Cambridge University Press, Cambridge U.K. (2003).
L.A. Ferreira and W.J. Zakrzewski, The concept of quasi-integrability: a concrete example, JHEP 05 (2011) 130 [arXiv:1011.2176] [INSPIRE].
D. Bazeia, L. Losano, J.M.C. Malbouisson and R. Menezes, Classical behavior of deformed sine-Gordon models, Physica D 237 (2008) 937 [arXiv:0708.1740] [INSPIRE].
V.G. Drinfeld and V.V. Sokolov, Lie algebras and equations of Korteweg-de Vries type, J. Sov. Math. 30 (1984) 1975 [INSPIRE].
V.G. Drinfeld and V.V. Sokolov, Equations of Korteweg-de Vries type and simple Lie algebras, Sov. Mat. Dokl. 23 (1981) 457.
D.I. Olive and N. Turok, Local conserved densities and zero curvature conditions for Toda lattice field theories, Nucl. Phys. B 257 (1985) 277 [INSPIRE].
D.I. Olive and N. Turok, The Toda lattice field theory hierarchies and zero curvature conditions in Kac-Moody algebras, Nucl. Phys. B 265 (1986) 469 [INSPIRE].
H. Aratyn, L.A. Ferreira, J.F. Gomes and A.H. Zimerman, The conserved charges and integrability of the conformal affine Toda models, Mod. Phys. Lett. A 9 (1994) 2783 [hep-th/9308086] [INSPIRE].
L.A. Ferreira and W.J. Zakrzewski, A simple formula for the conserved charges of soliton theories, JHEP 09 (2007) 015 [arXiv:0707.1603] [INSPIRE].
B. Luther-Davies and Y.S. Kivshar, Dark optical solitons: physics and applications, Phys. Rept. 298 (1998) 81.
G.P. Agrawal, Nonlinear fiber optics: quantum electronics — principles and applications, Academic Press (1989).
C. Sulem and P.-L. Sulem, The nonlinear Schrödinger equation: self-focusing and wave collapse, Springer-Verlag (1999).
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1206.5808
Rights and permissions
About this article
Cite this article
Ferreira, L.A., Luchini, G. & Zakrzewski, W.J. The concept of quasi-integrability for modified non-linear Schrödinger models. J. High Energ. Phys. 2012, 103 (2012). https://doi.org/10.1007/JHEP09(2012)103
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP09(2012)103