HAL : in2p3-00310866, version 1
 arXiv : 0808.0139
 DOI : 10.3842/SIGMA.2009.017
 SIGMA 5 (2009) (2009) 017
 Comments on the dynamics of the Pais-Uhlenbeck oscillator
 (2009)
 We discuss the quantum dynamics of the Pais-Uhlenbeck oscillator. The Lagrangian of this higher-derivative model depends on two frequencies. When the frequencies are different, the free PU oscillator has a pure point spectrum that is dense everywhere. When the frequencies are equal, the spectrum is continuous. It is not bounded from below, running from minus to plus infinity, but this is not disastrous as the Hamiltonian is still Hermitian and the evolution operator is still unitary. Generically, the inclusion of interaction terms break unitarity, but in some special cases unitarity is preserved. We discuss also the nonstandard realization of the PU oscillator suggested by Bender and Mannheim, where the spectrum of the free Hamiltonian is positive definite, but wave functions grow exponentially for large real values of canonical coordinates. The free nonstandard PU oscillator is unitary when the frequencies are different, but unitarity is broken in the equal frequencies limit.
 Thème(s) : Mathématiques/Physique mathématiquePhysique/Physique mathématiquePhysique/Physique des Hautes Energies - ThéoriePhysique/Physique Quantique
 Lien vers le texte intégral : http://fr.arXiv.org/abs/0808.0139
 in2p3-00310866, version 1 http://hal.in2p3.fr/in2p3-00310866 oai:hal.in2p3.fr:in2p3-00310866 Contributeur : Dominique Girod <> Soumis le : Lundi 11 Août 2008, 14:41:59 Dernière modification le : Mercredi 23 Septembre 2009, 15:16:17