Abstract
We discuss the properties of the gas of primordial `stringy' black holes possibly formed in the high-curvature phase preceding the bouncing transition to the phase of standard cosmological evolution. We show that the regime dominated by such a string-hole gas can be consistently described by explicit solutions of the string effective action including first-order $\alpha'$ corrections. We present a phase space analysis of the stability of such solutions comparing the results obtained from different actions and including the possibility of $O(d,d)$-symmetric configurations.
Highlights
Since the rise of string theory as an effort to unify quantum field theory and general relativity, there has been a number of attempts to construct very early Universe cosmological scenarios embedded in string theory
One defines a string hole (SH) as an object that has the mass of a Schwarzschild black hole (BH) confined within a radius given by the string length, i.e., MSH 1⁄4 MBH ∼ RDBH−3=G and RSH 1⁄4 RBH 1⁄4 ls, so MSH ∼ lDs −3=G. (For a review of D-dimensional black holes, see, e.g., Ref. [42])
We revisited the proposal that the stringy high-energy state of the Universe is a string-hole gas, i.e., a gas of black holes lying on the string-/black-hole correspondence curve
Summary
Since the rise of string theory as an effort to unify quantum field theory and general relativity, there has been a number of attempts to construct very early Universe cosmological scenarios embedded in string theory. [34] that the past-trivial string vacuum of the tree-level low-energy effective gravidilaton action is generically prone to gravitational instability, leading to the formation of black holes All these studies indicate that the state of a contracting universe at high densities is composed of many black holes. III A that with tree-level dilaton gravity as a low-energy effective action of string theory dynamics that matches the properties of a string-hole gas is only obtained in finely tuned situations It is only when α0 corrections are included that we find more appropriate solutions. The number of spatial dimensions is denoted by d, and we assume that it is an integer greater than or equal to 3 throughout
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