Cosmological Kinetic Mixing

TL;DR

This paper extends kinetic mixing concepts to relativistic particles and cosmology, revealing how interactions can rescale masses and cosmological constants, offering new perspectives on dark matter and energy.

Contribution

It introduces a novel application of kinetic mixing to time reparametrization invariant theories, providing new insights into dark sector interactions.

Findings

Kinetic mixing can rescale particle masses.

Cosmological constant can be reduced via kinetic mixing.

Numerical solutions show observable effects of mixing.

Abstract

In this paper we generalize the kinetic mixing idea to time reparametrization invariant theories, namely, relativistic point particles and cosmology in order to obtain new insights for dark matter and energy. In the first example, two relativistic particles interact through an appropriately chosen coupling term. It is shown that the system can be diagonalized by means of a non-local field redefinition, and, as a result of this procedure, the mass of one the particles gets rescaled. In the second case, inspired by the previous example, two cosmological models (each with its own scale factor) are made to interact in a similar fashion. The equations of motion are solved numerically in different scenarios (dust, radiation or a cosmological constant coupled to each sector of the system). When a cosmological constant term is present, kinetic mixing rescales it to a lower value which may be more amenable to observations.