Dark Photons Could help Solve a Grand Challenge Facing Modern Physics

Dark photons are hypothetical particles that could account for observations that cannot be explained by the Standard Model of particle physics.

“We are trying to solve the problem of understanding one of the grand challenges facing modern science — how to find what type of particle dark matter is composed of,” said Professor Anthony Thomas, a physicist with the ARC Centre of Excellence for Dark Matter Particle Physics and CSSM at the University of Adelaide.

“Dark matter is five times more plentiful than visible matter that physicists have explored so successfully and of which we are composed.”

“We do not know what kind of particle makes up dark matter but we, along with a very large number of people around the world, want to understand this.”

In a new paper in the journal Physical Review Letters, Professor Thomas and his colleagues at the University of Adelaide explored the possibility that dark matter exists in the form of a dark massive photon.

“We are exploring the discovery potential of a new tool, parity violating electron scattering, which has been enabled by the upgrade at Thomas Jefferson National Accelerator Facility (JLab) in the United States,” Professor Thomas said.

“Parity violation is like looking at the difference between what happens in the laboratory and what happens when you view the experiment in a mirror.”

“The differences are very small, typically less than a part per million, but incredibly precise measurements enable us to observe this and use it as a signal of the existence of this new particle.”

“We found a mysterious result for the size of a lead nucleus which may be explained if there is a particular new dark matter particle, the dark photon,” he added.

New experiments where changes in the predictions without any dark matter could be modified by as much as 5%, with the difference providing direct evidence for this type of dark matter.

“A vital test of the existence of such a particle could be provided by future experiments into the behavior of electrons, positrons and deuterons,” Professor Thomas said.

“Visible matter is just the tip of the iceberg. With a better understanding of dark matter, the part of the iceberg below the surface, we will shine a light on the secrets of our Universe.”


Sensitivity of Parity-Violating Electron Scattering to a Dark Photon

A. W. Thomas, X. G. Wang, and A. G. Williams

Phys. Rev. Lett. 129, 011807 – Published 1 July 2022https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.011807