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Quantum many-body systems exactly solved by special functions
KTH, School of Engineering Sciences (SCI), Theoretical Physics.
2007 (English)Doctoral thesis, monograph (Other scientific)
Abstract [en]

This thesis concerns two types of quantum many-body systems in one dimension exactly solved by special functions: firstly, systems with interactions localised at points and solved by the (coordinate) Bethe ansatz; secondly, systems of Calogero-Sutherland type, as well as certain recently introduced deformations thereof, with eigenfunctions given by natural many-variable generalisations of classical (orthogonal) polynomials. The thesis is divided into two parts. The first provides background and a few complementary results, while the second presents the main results of this thesis in five appended scientific papers. In the first paper we consider two complementary quantum many-body systems with local interactions related to the root systems CN, one with delta-interactions, and the other with certain momentum dependent interactions commonly known as delta-prime interactions. We prove, by construction, that the former is exactly solvable by the Bethe ansatz in the general case of distinguishable particles, and that the latter is similarly solvable only in the case of bosons or fermions. We also establish a simple strong/weak coupling duality between the two models and elaborate on their physical interpretations. In the second paper we consider a well-known four-parameter family of local interactions in one dimension. In particular, we determine all such interactions leading to a quantum many-body system of distinguishable particles exactly solvable by the Bethe ansatz. We find that there are two families of such systems: the first is described by a one-parameter deformation of the delta-interaction model, while the second features a particular one-parameter combination of the delta and the delta-prime interactions. In papers 3-5 we construct and study particular series representations for the eigenfunctions of a family of Calogero-Sutherland models naturally associated with the classical (orthogonal) polynomials. In our construction, the eigenfunctions are given by linear combinations of certain symmetric polynomials generalising the so-called Schur polynomials, with explicit and rather simple coefficients. In paper 5 we also generalise certain of these results to the so-called deformed Calogero-Sutherland operators.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , viii, 65 p.
Trita-FYS, ISSN 0280-316X ; 2007:37
Keyword [en]
Quantum many-body systems, integrable systems, special functions
National Category
Other Physics Topics
URN: urn:nbn:se:kth:diva-4416ISBN: 978-91-7178-695-1OAI: diva2:12212
Public defence
2007-06-13, The Svedbergssalen (FD5), Albanova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:15
QC 20100712Available from: 2007-05-31 Created: 2007-05-31 Last updated: 2010-07-12Bibliographically approved

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