2015/12/31 by Jasdeep S. Bains, Mark P. Hertzberg, Frank Wilczek · 26 citations
Physics and Astronomy · #Attractor #Black Holes and Theoretical Physics #Classical mechanics #Cosmology #Cosmology and Gravitation Theories #Dark energy #Friedmann–Lemaître–Robertson–Walker metric #Galaxies: Formation, Evolution, Phenomena #Hubble's law #Instability #Physics #Quantum electrodynamics #Quantum mechanics #Scalar field #Symmetry breaking #Theoretical physics #astro-ph.CO #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1088/1475-7516/2017/05/011
published in Journal of Cosmology and Astroparticle Physics 2017(05), 011 (Institute of Physics) · 36 pages, 15 figures. V2: Updated to version published in JCAP
arxiv created 2017/05/04 · openalex publication_date 2017/05/04 · arxiv updated 2017/05/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
In expanding FRW spacetimes, it is usually the case that homogeneous scalar fields redshift and their amplitudes approach limiting values: Hubble friction usually ensures that the field relaxes to its minimum energy configuration, which is usually a static configuration. Here we discover a class of relativistic scalar field models in which the attractor behavior is the field oscillating indefinitely, with finite amplitude, in an expanding FRW spacetime, despite the presence of Hubble friction. This is an example of spontaneous breaking of time translation symmetry. We find that the effective equation of state of the field has average value ⟨ w ⟩=−1, implying that the field itself could drive an inflationary or dark energy dominated phase. This behavior is reminiscent of ghost condensate models, but in the new models, unlike in the ghost condensate models, the energy-momentum tensor is time dependent, so that these new models embody a more definitive breaking of time translation symmetry. We explore (quantum) fluctuations around the homogeneous background solution, and find that low k -modes can be stable, while high k -modes are typically unstable. We discuss possible interpretations and implications of that instability.