A global team of scientists has delved deeper into understanding the complex nature of dark matter, which comprises a staggering 84% of the universe’s matter content. Their focus has been on the ‘dark photon’, a theoretical particle that can bridge the gap between the elusive dark sector and regular matter.
New insights into dark matter emerge as researchers explore ‘the dark’ photo‘ hypothesis that challenges the standard model hypothesis.
Led by experts at the University of Adelaide, a team of international researchers has uncovered further clues in the quest for insight into the nature of dark matter.
“Dark matter makes up 84 percent of the matter in the universe, but we know very little about it,” said Professor Anthony Thomas, Senior Professor of Physics, University of Adelaide.
“The existence of dark matter has been firmly established from its gravitational interactions, but its precise nature continues to elude us despite the best efforts of physicists around the world.”
“The key to understanding this mystery may lie in the dark photon, a theoretically massive particle that can serve as a portal between the dark sector of particles and regular matter.”
“Our work shows that the dark photon hypothesis is favored over the standard model hypothesis with a significance of 6.5 sigma, providing evidence for a particle discovery.” — Professor Anthony Thomas
The dark photon and its meaning
Regular matter, of which we and our physical world are composed, is far less abundant than dark matter: five times more dark matter exists than regular matter. Finding out more about dark matter is one of the biggest challenges for physicists around the world.
The dark photon is a hypothetical hidden sector particle, proposed as a force carrier similar to the photon of electromagnetism, but potentially associated with dark matter. Testing existing theories about dark matter is one of the approaches that researchers such as Professor Thomas, along with colleagues Professor Martin White, Dr. Xuangong Wang and Nicholas Hunt-Smith, who are members of the Australian Research Council (ARC) Center of Excellence for Dark Matter Particle Physics, are pursuing more clues to this elusive but extremely important substance.
Insights from particle collisions
“In our latest study, we investigate the potential effects that a dark photon can have on the complete set of experimental results from the deep inelastic scattering process,” Professor Thomas said.
Analysis of the byproducts of collisions of particles accelerated to extremely high energies provides scientists with good evidence of the structure of the subatomic world and the laws of nature that govern it.
In particle physics, deep inelastic scattering is the name of a process used to probe the interior of hadrons (especially the baryons, such as protons and neutrons), using electrons, muons and neutrinos.
“We have made use of the state-of-the-art Jefferson Lab Angular Momentum (JAM) parton distribution function global analysis framework that has modified the underlying theory to allow for the possibility of a dark photon,” Professor Thomas said.
“Our work shows that the dark photon hypothesis is favored over the standard model hypothesis with a significance of 6.5 sigma, providing evidence for a particle discovery.”
The team, which includes researchers from the University of Adelaide and colleagues at the Jefferson Laboratory in Virginia, USA, has published its findings in Journal of High Energy Physics.
Reference: “Global QCD analysis and dark photons” by NT Hunt-Smith, W. Melnitchouk, N. Sato, AW Thomas, XG Wang and MJ White on behalf of the Jefferson Lab Angular Momentum (JAM) collaboration, 15 September 2023, Journal of High Energy Physics.
DOI: 10.1007/JHEP09(2023)096
