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**A complete treatment of low-energy scattering in one dimension.**
*(English)*
Zbl 0567.47008

The authors present a systematic analysis of low-energy scattering for Schrödinger Hamiltonians, H, on the entire real line, taking into account explicitly the possibility of zero-energy resonances of H. The possible occurrence of these resonances leads to a classification of essentially two cases i.e. H has no zero-energy resonances \((=\) generic case) and H has a zero-energy resonance of multiplicity 1. The potential conditions are
\[
(1)\quad \int_{{\mathbb{R}}}dx(1+| x|^ 2)| V(x)| <\infty \quad and\quad (2)\quad \int_{{\mathbb{R}}}dx V(x)\neq 0.
\]
For these cases the low-energy behavior of the transition operator T(k) is described. In particular, for potentials satisfying conditions (1), (2) and (3) \(\int_{{\mathbb{R}}}dx[\exp a| x|]| V(x)| <\infty,\) \(a>0\), recursion relations are established for the coefficients in the Taylor expansions for T(k) (generic case) or Laurent expansions for T(k) (other cases). Also Taylor expansions for the reflection and transmission coefficients are presented in all cases. Finally, two sets of trace relations involving the continuous and point spectrum of H are proved. As a special case Levinson’s theorem for scattering on the line is obtained. Its structure completely changes in comparison with three dimensions.

If one is interested in asymptotic expansions instead of analytic ones, it is shown how the exponential fall off conditions on the potential can be relaxed. An extension of this work replacing condition (2) by \(\int_{{\mathbb{R}}}dx V(x)=0\), by D. Bollé, F. Gesztesy and M. Klaus will appear in J. Math. Anal. Appl. (1985).

If one is interested in asymptotic expansions instead of analytic ones, it is shown how the exponential fall off conditions on the potential can be relaxed. An extension of this work replacing condition (2) by \(\int_{{\mathbb{R}}}dx V(x)=0\), by D. Bollé, F. Gesztesy and M. Klaus will appear in J. Math. Anal. Appl. (1985).

### MSC:

47A40 | Scattering theory of linear operators |

81U05 | \(2\)-body potential quantum scattering theory |

34L99 | Ordinary differential operators |

47B06 | Riesz operators; eigenvalue distributions; approximation numbers, \(s\)-numbers, Kolmogorov numbers, entropy numbers, etc. of operators |

46N99 | Miscellaneous applications of functional analysis |