Detecting Dark Matter: Dark Photons

Introduction

Recently, I read an article discussing the current lack of success we have had detecting dark matter. I wanted to take this opportunity to take a look at a recent experiment which sought to detect dark photons. These dark photons are considered “dark” because they are unlike regular photons and are not related to the electromagnetic force. Instead, their existence would require the existence of entirely new force to facilitate the interactions between light and dark matter. Although the experiment proved to be inconclusive, it could potentially suggest the existence of dark photons in a larger and more detailed study.

Before we begin I would like to say that I am not a physicist and that the following analysis is my hopeful interpretation of the experiment.

The Experiment

In February of 2017 a group of scientist published their analysis based on some of the data collected from the BABAR experiment. They used the data to detect dark photons through analyzing the events resulting from the collision of an electron and a positron. They theorized that although the resulting wavelength would be “invisible” they could still detect a change in the system's mass (through high-energy photon) accompanied by a decrease in the system's overall momentum and energy. Below are some of the graphs from the study.

The first graph overlays the mixing strength squared from the experiment (the black dots) over the he maximum-likelihood values of the mixing strength squared.

Below is a graph from the study depicting the relative significance of the data across the mass’ range of m_A’ ≤8 GeV. As you can tell there are multiple regions where the gains in significance, which correspond changes in the observed mixing strength squared!

Unfortunately, as I pointed out earlier this data is not conclusive when compared to either its Bayesian of Profile-likelihood limits. Hopefully, with more knowledge on the subject or with more detailed predictions we can reduce their upper limits and maybe even use a similar method to conclusively observe dark photons!

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