Supersymmteric Null-like Holographic Cosmologies

TL;DR

This paper constructs supersymmetric, time-dependent holographic cosmological solutions with null-like singularities, exploring their dual quantum field theories and the evolution of degrees of freedom near the big bang.

Contribution

It introduces a new class of 1/4-BPS null-like domain-wall solutions in supergravity, linking them to boundary QFTs with evolving couplings and UV cutoff, and analyzes the holographic c-function behavior.

Findings

The holographic c-function increases towards the big bang, indicating divergent degrees of freedom.

The solutions exhibit a null-like big bang singularity.

The c-theorem is satisfied during cosmological evolution.

Abstract

We construct a new class of 1/4-BPS time dependent domain-wall solutions with null-like metric and dilaton in type II supergravities, which admit a null-like big bang singularity. Based on the domain-wall/QFT correspondence, these solutions are dual to 1/4-supersymmetric quantum field theories living on a boundary cosmological background with time dependent coupling constant and UV cutoff. In particular we evaluate the holographic $c$ function for the 2-dimensional dual field theory living on the corresponding null-like cosmology. We find that this $c$ function runs in accordance with the $c$-theorem as the boundary universe evolves, this means that the number of degrees of freedom is divergent at big bang and suggests the possible resolution of big bang singularity.