Bouncing and Accelerating Solutions in Nonlocal Stringy Models

Abstract

A general class of cosmological models driven by a non-local scalar field inspired by string field theories is studied. In particular cases the scalar field is a string dilaton or a string tachyon. A distinguished feature of these models is a crossing of the phantom divide. We reveal the nature of this phenomena showing that it is caused by an equivalence of the initial non-local model to a model with an infinite number of local fields some of which are ghosts. Deformations of the model that admit exact solutions are constructed. These deformations contain locking potentials that stabilize solutions. Bouncing and accelerating solutions are presented.

Minor corrections, references added, published in JHEP

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• Dynamics with Infinitely Many Derivatives: The Initial Value Problem
• Route to nonlocal cosmology
• Newtonian limit of nonlocal cosmology
• Dynamics in Nonlocal Cosmological Models Derived from String Field Theory
• Diffusing non-local inflation: Solving the field equations as an initial value problem
• On the Null Energy Condition and Cosmology
• Dynamics in nonlocal linear models in the Friedmann-Robertson-Walker metric
• Dynamics and Stability of Light-Like Tachyon Condensation
• Zeta Nonlocal Scalar Fields
• Some Lagrangians with Zeta Function Nonlocality
• Lagrangians with Riemann Zeta Function