Abstract
Faddeev and Zakharov determined the trace formulas for the KdV equation with real initial conditions in 1971. We reprove these results for the KdV equation with complex initial conditions. The Lax operator is a Schrödinger operator with complex-valued potentials on the line. The operator has essential spectrum on the half-line plus eigenvalues (counted with algebraic multiplicity) in the complex plane without the positive half-line. We determine series of trace formulas. Here we have a new term: a singular measure, which is absent for real potentials. Moreover, we estimate of sum of the imaginary part of eigenvalues plus the singular measure in terms of the norm of potentials. The proof is based on classical results about the Hardy spaces.
DOI 10.1134/S106192084010096
Similar content being viewed by others
References
M. Ablowitz and P. Clarkson, Solitons, Nonlinear Evolution Equations And Inverse Scattering, vol. 149, Cambridge university press, 1991.
M. J. Ablowitz and H. Segur, Solitons and the Inverse Scattering Transform, Society for Industrial and Applied Mathematics, 1981.
A. A. Abramov, A. Aslanyan, and E. B. Davies, “Bounds on Complex Eigenvalues and Resonances”, J. Phys. A, 34 (2001), 57–72.
V. S. Buslaev, “The Trace Formulae and Certain Asymptotic Estimates of the Kernel of the Resolvent for the SchröDinger Operator in Three-Dimensional Space (Russian)”, Probl. Math. Phys. No. I, Spectral Theory and Wave Processes, (1966), 82–101.
V. Buslaev and L. Faddeev, “Formulas for the Traces for a Singular Sturm-Liouville Differential Operator (English translation)”, Dokl. AN SSSR, 132:1 (1960), 451–454.
P. Deift and E. Trubowitz, “Inverse Scattering on the Line”, Comm. Pure Appl. Math., 32 (1979), 121–251.
M. Demuth, M. Hansmann, and G. Katriel, “Lieb-Thirring Type Inequalities for Schrödinger Operators with a Complex-Valued Potential”, Integral Equations Operator Theory, 75:1 (2013), 1–5.
M. Demuth, M. Hansmann, and G. Katriel, “On the Discrete Spectrum of Non-Selfadjoint Operators”, J. Funct. Anal., 257:9 (2009), 2742–2759.
L. Faddeev, “The Inverse Problem in the Quantum Theory of Scattering”, J. Math. Phys., 4:1 (1963), 72–104; Uspekhi Mat. Nauk, (1959).
L. Faddeev, “Properties of the S-Matrix of the One-Dimensional Schrödinger Equation”, Tr. Mat. Inst. Steklova, 73 (1964), 314–336; Amer. Math. Soc. Transl. Ser. 2, 65 (1967), 139–166.
L. Faddeev and V. Zakharov, “Korteveg-de Vries Equation: a Completely Integrable Hamiltonian System”, Funct. Anal. Appl., 5 (1971), 18–27.
R. Frank, A. Laptev, and O. Safronov, “On The Number of Eigenvalues of Schrödinger Operators with Complex Potentials”, J. London Math. Soc., 2:94 (2016), 377–390.
R. L. Frank and B. Simon, “Eigenvalue Bounds for Schrödinger Operators with Complex Potentials. II”, J. Spectr. Theory, 7:3 (2017), 633–658.
R. L. Frank, A. Laptev, E. H. Lieb, and R. Seiringer, “Lieb–Thirring Inequalities for Schrödinger Operators with Complex-Valued Potentials”, Lett. Math. Phys., 77 (2006), 309–316.
C. S. Gardner, J. M. Greene, M. D. Kruskal, and R. M. Muira, “Method for Solving the Korteweg-De Vries Equation”, Phys. Rev. Lett., 19 (1967), 1095–1097.
J. Garnett, Bounded Analytic Functions, Academic Press, New York, London, 1981.
I. Gohberg and M. Krein, Introduction to the Theory of Linear Nonself-adjoint Operators, Translated from the Russian, Translations of Mathematical Monographs, Vol. 18 AMS, Providence, R.I., 1969.
P. Kargaev and E. Korotyaev, “Effective Masses and Conformal Mappings”, Comm. Math. Phys., 169:3 (1995), 597–625.
R. Killip and B. Simon, “Sum Rules and Spectral Measures of Schrödinger Operators with \(L^2\) Potentials”, Ann. of Math., 2:170 (2009), 739–782.
P. Koosis, Introduction to \(H_p\) Spaces, volume 115 of Cambridge Tracts in Mathematic, 1998.
P. Koosis, The Logarithmic Integral I, Cambridge Univ. Press, Cambridge, London, New York, 1988.
E. Korotyaev, “The Estimates of Periodic Potentials in Terms of Effective Masses”, Comm. Math. Phys., 183:2 (1997), 383–400.
E. Korotyaev, “Estimates of Periodic Potentials in Terms of Gap Lengths”, Comm. Math. Phys., 197:3 (1998), 521–526.
E. Korotyaev, “Estimates for the Hill Operator”, I. J. Differential Equations, 162:1 (2000), 1–26.
E. Korotyaev, “Estimates of 1D Resonances In Terms of Potentials”, J. Anal. Math., 130 (2016), 151–166.
E. Korotyaev, “Trace Formulae for Schrödinger Operators on Lattice”, Russ. J. Math. Phys., 29:4 (2022), 542–557.
E. Korotyaev, “Trace Formulae for Schrödinger Operators with Complex-Valued Potentials”, Russ. J. Math. Phys., 27:1 (2020), 82–98.
E. Korotyaev, “Trace Formulas For Schrödinger Operators With Complex Potentials On Half-Line”, Lett. Math. Phys., 110 (2020), 1–20.
E. Korotyaev, “Trace Formulas for Time Periodic Complex Hamiltonians on Lattice”, J. Math. Anal. Appl., 534:1, No. 128045 (2024), 31.
E. Korotyaev and A. Laptev, “Trace Formulas for Complex Schrödinger Operators on Cubic Lattices”, Bull. Math. Sci., 8 (2018), 453–475.
E. Korotyaev and A. Pushnitski, “A Trace Formula and High-Energy Spectral Asymptotics for the Perturbed Landau Hamiltonian”, J. Funct. Anal., 217:1 (2004), 221–248.
E. Korotyaev and A. Pushnitski, “Trace Formulae and High Energy Asymptotics for the Stark Operator”, Comm. Partial Differential Equations, 28:3-4 (2003), 817–842.
M. Kruskal, R. Miura, C. Gardner, and N. Zabusky, “Korteweg–de Vries Equation and Generalizations, V. Uniqueness and Nonexistence of Polynomial Conservation Laws”, J. Math. Phys., 11:3 (1970), 952–960.
A. Laptev and O. Safronov, “Eigenvalue Estimates for Schrödinger Operators with Complex Potentials”, Comm. Math. Phys., 292:1 (2009), 29–54.
P. Lax, “Intergrals of Nonlinear Equations and Solitary Waves”, Comm. Pure Appl. Math., 21:2 (1968), 467–490.
M. Malamud and H. Neidhardt, “Trace Formulas for Additive and Non-Additive Perturbations”, Adv. Math., 274 (2015), 736–832.
V. Marchenko, Sturm-Liouville Operator and Applications, Birkhäuser, Basel, 1986.
A. Melin, “Operator Methods for Inverse Scattering on The Real Line”, Comm. Partial Differential Equations, 10 (1985), 677–786.
R. Miura, C. Gardner, and M. Kruskal, “Korteweg-de Vries Equation and Generalizations. II. Existence of Conservation Laws and Constants of Motion”, J. Math. Phys., 9:1204 (1968), 1204–1209.
S. Novikov, S. Manakov, L. Pitaevski, and V. Zakharov, Theory of Solitons. The Inverse Scattering Method, Consultants Bureau [Plenum], New York, 1984.
O. Safronov, “Estimates for Eigenvalues of the Schrödinger Operator with a Complex Potential”, Bull. London Math. Soc., 42:3 (2010), 452–456.
O. Safronov, “On a Sum Rule for Schrödinger Operators with Complex Potentials”, Proc. Amer. Math. Soc., 138:6 (2010), 2107–2112.
Acknowledgments
EK is grateful to Sergei Kuksin (Paris) for discussions about the KdV equetion, to Ari Laptev (London) for discussions about the Schrödinger operators with complex potentials, and to Alexei Alexandrov (St. Petersburg) for discussions and useful comments about Hardy spaces.
Funding
Our study was supported by the RSF grant No 19-71-30002.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
The authors of this work declare that they have no conflicts of interest.
Additional information
Publisher’s note. Pleiades Publishing remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Korotyaev, E. Trace Formulas for a Complex KdV Equation. Russ. J. Math. Phys. 31, 112–131 (2024). https://doi.org/10.1134/S106192084010096
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S106192084010096