Quantum phase transitions in the interacting boson model: Integrability, level repulsion, and level crossing

Description

We study the quantum phase transition mechanisms that arise in the interacting boson model. We show that the second-order nature of the phase transition from U(5) to O(6) may be attributed to quantum integrability, whereas all the first-order phase transitions of the model are due to level repulsion with one singular point of level crossing. We propose a model Hamiltonian with a true first-order phase transition for finite systems due to level crossings.

Abstract

DGI BFM2002-03315 BFM2000-1320-C02-02

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