# Cosmology of Lorentz fiber-bundle induced scalar-tensor theories

## TL;DR

This paper explores how scalar-tensor theories derived from Finsler-like geometries can model the universe's evolution, including dark energy and inflation, revealing new geometric origins of cosmological phenomena.

## Contribution

It introduces a novel scalar-tensor framework from Lorentz fiber-bundle Finsler geometry, showing its ability to describe dark energy, matter epochs, and inflation.

## Key findings

- Effective dark-energy sector with matter interaction
- Reproduction of universe's thermal history
- Inflationary solutions from geometric structure

## Abstract

We investigate the cosmological applications of scalar-tensor theories that arise effectively from the Lorentz fiber bundle of a Finsler-like geometry. We first show that the involved nonlinear connection induces a new scalar degree of freedom and eventually a scalar-tensor theory. Using both a holonomic and a nonholonomic basis, we show the appearance of an effective dark-energy sector, which additionally acquires an explicit interaction with the matter sector, arising purely from the internal structure of the theory. Applying the theory at late times we find that we can obtain the thermal history of the Universe, namely the sequence of matter and dark-energy epochs, and moreover the effective dark-energy equation-of-state parameter can be quintessencelike, phantomlike, or experience the phantom-divide crossing during cosmological evolution. Furthermore, applying the scenario at early times, we see that one can acquire an exponential de Sitter solution as well as obtain an inflationary realization with the desired scale-factor evolution. These features arise purely from the intrinsic geometrical structure of Finsler-like geometry and reveal the capabilities of the construction.