Dark photons: key to the mystery of dark matter?

Researchers explore the "dark photon" hypothesis, challenge the Standard Model hypothesis, and gain a new understanding of dark matter. Dark matter makes up 84% of the matter in the universe, and a global team of scientists has taken an in-depth look at its complex properties. Their research focuses on "dark photons," theoretical particles that have the potential to bridge the gap between elusive dark matter and regular matter.

An international team of researchers, led by experts from the University of Adelaide, has uncovered more clues as they explore the nature of dark matter. "Dark matter makes up 84% of the matter in the universe, yet we know very little about it," said Professor Anthony Thomas, Elder Professor of Physics at the University of Adelaide. "The existence of dark matter has been conclusively demonstrated from its gravitational interactions, but despite the best efforts of physicists around the world, its precise properties remain elusive. The key to understanding this mystery may lie in dark photons, which are theoretically massive particles that may be the gateway between the dark zone of particles and regular matter."

We and our physical world are made of ordinary matter, but there is far less ordinary matter than dark matter: there is five times as much dark matter as ordinary matter. Finding more information about dark matter is one of the biggest challenges facing physicists around the world.

Dark photons are hypothetical hidden sector particles thought to be force carriers similar to electromagnetic photons, but possibly related to dark matter. Scientists including Professor Thomas, a member of the Australian Research Council (ARC) Center of Excellence for Dark Matter Particle Physics, and colleagues Professor Martin White, Dr Xuangong Wang and Nicholas Hunter-Smith are testing existing dark matter theories to gain more clues about this elusive but important substance.

Professor Thomas said: "In our latest study, we investigated the potential impact that dark photons could have on a whole suite of experimental results from deep inelastic scattering processes. Analysis of the by-products of collisions of particles accelerated to extremely high energies provides scientists with strong evidence of the structure of the subatomic world and its natural laws. In particle physics, deep inelastic scattering is used to exploit electrons, muons and neutrons Trinos are the name for the process inside hadrons (especially baryons, such as protons and neutrons). We used the state-of-the-art Jefferson Laboratory Angular Momentum (JAM) parton distribution function global analysis framework to modify the underlying theory to account for the possibility of dark photons. Our work shows that the dark photon hypothesis outperforms the Standard Model hypothesis by a significance of 6.5 sigma, which constitutes evidence for the discovery of the particle.

The research team, which included scientists from the University of Adelaide and colleagues from the Jefferson Laboratory in Virginia, USA, published their findings in the Journal of High Energy Physics.