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For type IIB supergravity with a running axio-dilaton, we construct bulk solutions which admit a cosmological background metric of Friedmann-Robertson-Walker type. These solutions include both a dark radiation term in the bulk as well as a four-dimensional (boundary) cosmological constant, while gravity at the boundary remains non-dynamical. We holographically calculate the stress-energy tensor, showing that it consists of two contributions: The first one, generated by the dark radiation term, leads to the thermal fluid of N = 4 SYM theory, while the second, the conformal anomaly, originates from the boundary cosmological constant. Conservation of the boundary stress tensor implies that the boundary cosmological constant is time-independent, such that there is no exchange between the two stress-tensor contributions. We then study (de)confinement by evaluating the Wilson loop in these backgrounds. While the dark radiation term favours deconfinement, a negative cosmological constant drives the system into a confined phase. When both contributions are present, we find an oscillating universe with negative cosmological constant which undergoes periodic (de)confinement transitions as the scale of three space expands and re-contracts.Comment: 31 pages, 5 figures, v2: Reference adde

Topics:
High Energy Physics - Theory, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology

Year: 2011

DOI identifier: 10.1103/PhysRevD.84.026004

OAI identifier:
oai:arXiv.org:1105.1776

Provided by:
arXiv.org e-Print Archive

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