The analytic structure of the renormalized energy of the quartic anharmonic oscillator described by the Hamiltonian H= p 2 +x 2 +;x 4 is discussed and the dispersion relation for the renormalized energy is found. It follows from the analytic structure that the renormalized strong coupling expansion
Oscillation Theory and Renormalized Oscillation Theory for Jacobi Operators
✍ Scribed by Gerald Teschl
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 1009 KB
- Volume
- 129
- Category
- Article
- ISSN
- 0022-0396
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✦ Synopsis
We provide a comprehensive treatment of oscillation theory for Jacobi operators with separated boundary conditions. Our main results are as follows: If u solves the Jacobi equation (Hu
(in the weak sense) on an arbitrary interval and satisfies the boundary condition on the left or right, then the dimension of the spectral projection P (& , *) (H ) of H equals the number of nodes (i.e., sign flips if a(n)<0) of u. Moreover, we present a reformulation of oscillation theory in terms of Wronskians of solutions, thereby extending the range of applicability for this theory; if * 1, 2 # R and if u 1, 2 solve the Jacobi equation Hu j =* j u j , j=1, 2 and respectively satisfy the boundary condition on the leftÂright, then the dimension of the spectral projection P (*1, *2) (H ) equals the number of nodes of the Wronskian of u 1 and u 2 . Furthermore, these results are applied to establish the finiteness of the number of eigenvalues in essential spectral gaps of perturbed periodic Jacobi operators.
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