# Articles by T. Berggren and P. Lind

## Seminal articles

Interpretation of the imaginary part of an observable calculated in the Berggren basis

T. Berggren

*Expectation value of an operator in a resonant state*

Phys. Lett. B**373**, 1 (1996) articleOperator equivalent of the Berggren basis

T. Berggren and P. Lind

*Resonant state expansion of the resolvent*

Phys. Rev. C**47**, 768 (1993) articleFormulation of the Berggren basis

T. Berggren

*On the use of resonant states in eigenfunction expansions of scattering and reaction amplitudes*

Nucl. Phys. A**109**, 265 (1968) article

## All articles

T. Berggren

*Expectation value of an operator in a resonant state*

Phys. Lett. B**373**, 1 (1996) article- P. Lind, R. J. Liotta, E. Maglione and T. Vertse

*Resonant state expansions of the continuum*

Z. Phys. A**347**, 231 (1994) articleLast (prescient) sentence in the article:

–

*We consider this a proof that the set of single-particle states in the Berggren and Mittag-Leffler expansions can be used as representation in shell-model calculations where the continuum plays an important role.* T. Berggren and P. Lind

*Resonant state expansion of the resolvent*

Phys. Rev. C**47**, 768 (1993) articleP. Lind

*Completeness relations and resonant state expansions*

Phys. Rev. C**47**, 1903 (1993) articleT. Berggren

*Completeness relations, Mittag-Leffler expansions and the perturbation theory of resonant states*

Nucl. Phys. A**389**, 261 (1982) articleT. Berggren

*Resonance effects in the binding of a nuleon to an unbound core*

Nucl. Phys. A**361**, 102 (1981) articleT. Berggren

*On the asymptotic behaviour of the effective form factor potential due to an ubound core*

Nucl. Phys. A**330**, 381 (1979) articleT. Berggren

*On the interpretation of complex cross sections for production of resonant final states*

Phys. Lett. B**73**, 389 (1978) articleG. Ohlen and T. Berggren

*Break-up reactions leading to resonant final states*

Nucl. Phys. A**272**, 21 (1976) articleT. Berggren

*On the treatment of resonant final states in direct reactions*

Nucl. Phys. A**169**, 353 (1971) articleT. Berggren

*On the use of resonant states in eigenfunction expansions of scattering and reaction amplitudes*

Nucl. Phys. A**109**, 265 (1968) articleD. F. Jackson and T. Berggren

*Partial wave analysis of the \({ ( p , 2p ) }\) reaction*

Nucl. Phys.**62**, 353 (1965) articleT. Berggren

*Overlap integrals and single-particle wave functions in direct interaction theories*

Nucl. Phys.**72**, 337 (1965) articleT. Berggren and G. Jacob

*Quasi-free proton-proton scattering in \({ 1p }\)-shell nuclei*

Nucl. Phys.**47**, 481 (1963) article- T. Berggren, G. E. Brown and G. Jacob

*A remark on quasi-free scattering*

Phys. Lett.**1**, 88 (1962) article

## Links

FRIB-Theory Alliance workshop 2018:

*From bound states to the continuum: Connecting bound state calculations with scattering and reaction theory*website; Talk on*The single-particle Berggren basis in structure calculations*slides*Symmetry in the world of atomic nuclei*by I. Ragnarsson and S. Åberg, Lund University; See slide on T. Berggren*Many-body open quantum systems: From atomic nuclei to quantum dots*at the ECT*, Trento, Italy, 2007; Talk on*40 years of the Berggren representation*by T. Vertse slides.

## Retrospectively funny T. Berggren quote

- T. Berggren

*Resonance State Expansions in Nuclear Physics*

*Resonances, The Unifying Route Towards the Formulation of Dynamical Processes. Foundations and Applications in Nuclear, Atomic, and Molecular Physics*. Proceedings of a Symposium held at Lertorpet, Värmland, Sweden, 1987. Edited by E. Brändas and N. Elander. Lecture Notes in Physics**325**. Berlin, Springer-Verlag, 1989, p.105 articleThe Next Generation: What More Can We Do?

The question in the title of this chapter is a suitable point for finishing this brief and incomplete review of resonance state expansions based on completeness. The situation is, I think, that we have a lot more to do in this field. My own activity here is, at present, very low. If there is still some interest in deep hole states in nuclei when I get time for them (they are highly excited, unbound, and decay via a kind of Auger process), then I would like to play with them for a while. Many intricate problems remain to be solved. There is an abundance of possible applications of resonance state expansions. The younger generation of physicists can just pick up a problem which appeals to their taste and work happily ever after.