# Modified Gravity Theories Based on the Non-Canonical Volume-Form Formalism

## TL;DR

This paper explores modified gravity theories using non-canonical volume-form formalism, leading to novel cosmological models that unify dark energy and dark matter, and propose stable universe solutions without a Big Bang.

## Contribution

It introduces new gravity-matter models based on non-canonical volume-forms, providing unified dark sector descriptions and stable universe solutions without fine-tuning.

## Key findings

- Unified dark energy and dark matter as a single scalar entity
- Stable emergent universe solution without Big Bang
- Suppression of fifth force without fine-tuning

## Abstract

We present a concise description of the basic features of gravity-matter models based on the formalism of non-canonical spacetime volume-forms in its two versions: the method of non-Riemannian volume-forms (metric-independent covariant volume elements) and the dynamical spacetime formalism. Among the principal outcomes we briefly discuss: (i) quintessential universe evolution with a gravity-"inflaton"-assisted suppression in the "early" universe and, respectively, dynamical generation in the "late" universe of Higgs spontaneous electroweak gauge symmetry breaking; (ii) unified description of dark energy and dark matter as manifestations of a single material entity - a second scalar field "darkon"; (iii)unification of dark energy and dark matter with diffusive interaction among them; (iv) explicit derivation of a stable "emergent universe" solution, i.e., a creation without Big Bang; (v) mechanism for suppression of 5-th force without fine-tuning.