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How is spontaneous symmetry breaking possible?

Baker, David John and Halvorson, Hans (2011) How is spontaneous symmetry breaking possible? [Preprint]

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    We pose and resolve a seeming paradox about spontaneous symmetry breaking in the quantum theory of infinite systems. For a symmetry to be spontaneously broken, it must not be implementable by a unitary operator. But Wigner's theorem guarantees that every symmetry is implemented by a unitary operator that preserves transition probabilities between pure states. We show how it is possible for a unitary operator of this sort to connect the folia of unitarily inequivalent representations. This result undermines interpretations of quantum theory that hold unitary equivalence to be necessary for physical equivalence.

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    Item Type: Preprint
    Keywords: algebraic quantum field theory, symmetry breaking, Wigner's theorem
    Subjects: Specific Sciences > Physics > Quantum Field Theory
    Specific Sciences > Physics > Symmetries/Invariances
    Depositing User: David Baker
    Date Deposited: 14 Mar 2011 06:54
    Last Modified: 03 Jul 2013 02:59
    Item ID: 8517

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