Singularity crossing, transformation of matter properties and the problem of parametrization in field theories

TL;DR

This paper explores cosmological models with soft future singularities, demonstrating how matter property transformations enable smooth crossing of these singularities, and compares approaches to crossing Big Bang-Big Crunch singularities.

Contribution

It introduces methods for smooth singularity crossing in models with tachyon fields or perfect fluids, expanding understanding of matter transformations in cosmological singularities.

Findings

Smooth crossing of soft singularities achieved in specific models

Transformations of matter properties facilitate singularity crossing

Comparison of different approaches to Big Bang-Big Crunch crossing

Abstract

We investigate particular cosmological models, based either on tachyon fields or on perfect fluids, for which soft future singularities arise in a natural way. Our main result is the description of a smooth crossing of the soft singularity in models with an anti-Chaplygin gas or with a particular tachyon field in the presence of dust. Such a crossing is made possible by certain transformations of matter properties. We discuss and compare also different approaches to the problem of crossing of the Big Bang - Big Crunch singularities.