2021-12-01T21:08:08Zhttps://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1606782020-12-13T09:13:01Zcom_10261_135com_10261_4col_10261_388
http://hdl.handle.net/10261/160678
http://dx.doi.org/10.1016/j.aop.2016.11.005
340213
Dirac fields in flat FLRW cosmology: Uniqueness of the Fock quantization
Springer
2016
Cortez, Jerónimo
Elizaga Navascués, Beatriz
Martín-Benito, Mercedes
Mena Marugán, Guillermo A.
Velhinho, José M.
Uniqueness criteria
Fock quantization
Quantum field theory in curved spacetimes
Unitarity in cosmological backgrounds
2016-11-22
13 pags.
We address the issue of the infinite ambiguity that affects the construction of a Fock quantization of a Dirac field propagating in a cosmological spacetime with flat compact sections. In particular, we discuss a physical criterion that restricts to a unique possibility (up to unitary equivalence) the infinite set of available vacua. We prove that this desired uniqueness is guaranteed, for any possible choice of spin structure on the spatial sections, if we impose two conditions. The first one is that the symmetries of the classical system must be implemented quantum mechanically, so that the vacuum is invariant under the symmetry transformations. The second and more important condition is that the constructed theory must have a quantum dynamics that is implementable as a (non-trivial) unitary operator in Fock space. Actually, this unitarity of the quantum dynamics leads us to identify as explicitly time dependent some very specific contributions of the Dirac field. In doing that, we essentially characterize the part of the dynamics governed by the Dirac equation that is unitarily implementable. The uniqueness of the Fock vacuum is attained then once a physically motivated convention for the concepts of particles and antiparticles is fixed.
Consejo Nacional de Ciencia y Tecnología (México)
Universidad Nacional Autónoma de México
Netherlands Organization for Scientific Research
Ministerio de Economía y Competitividad (España)
Radboud University
European Cooperation in Science and Technology
Annals of Physics
2017
376
76
88