Constraining Millicharged dark matter with Gravitational positivity bounds

TL;DR

This paper uses gravitational positivity bounds combined with astrophysical data to significantly restrict the parameter space of millicharged fermion dark matter models with a massless dark photon, especially for lighter dark matter.

Contribution

It derives novel constraints on millicharged dark matter models using gravitational positivity bounds and astrophysical observations, narrowing the viable parameter space.

Findings

Most parameter regions are excluded for dark matter lighter than solar core temperature.

Gravitational positivity bounds provide strong lower bounds on model parameters.

Combining bounds from different sources tightens constraints on millicharged dark matter.

Abstract

Gravitational positivity bounds provide consistency conditions for effective field theories with gravity. They turn out to be phenomenologically useful by providing lower bounds in parameters of new physics beyond the Standard Models (BSM). In this paper, we derive constraints on millicharged fermion dark matter models with massless dark photon using gravitational positivity bounds. Combining them with upper bounds from cosmological and astrophysical observations, we can severely constrain the parameter space of the model. In particular, we show that when the dark matter mass is lighter than the solar core temperature, most of the parameter region is excluded by combining gravitational positivity bounds and the stellar bounds.