‘Dark photons’ could be the key to understanding dark matter

We know dark matter is there. Models of the Universe literally fall apart without it. But dark matter remains elusive.  

Now a new study published in Journal of High Energy Physics suggests the hypothetical particle called ‘dark photons’ could be the key.

“The existence of dark matter has been firmly established from its gravitational interactions, yet its precise nature continues to elude us, despite the best efforts of physicists around the world,” says one of the authors of the paper, Professor Anthony Thomas from the University of Adelaide.

“The key to understanding this mystery could lie with the dark photon, a theoretical massive particle that may serve as a portal between the dark sector of particles and regular matter.” 

Dark photons – also known as hidden photons – are hypothesised to be a force carrying particle similar to photons but connected to dark matter.

Although there are plenty of opinions about what dark matter could be, dark photons are a favourite because they would require only a tweak to the Standard Model of particle physics.

Of course, hypothesising what dark matter could be is only the easy half. You also have to prove that it exists.

“In our latest study, we examine the potential effects that a dark photon could have on the complete set of experimental results from the deep inelastic scattering process,” said Thomas.

Inelastic scattering is when the kinetic energy of a particle changes after it’s been hit or collided with.

This sort of technique is used regularly in particle physics to detect hard to find particles – for example at the Large Hadron Collider.

“We have made use of the state-of-the-art Jefferson Lab Angular Momentum (JAM) parton distribution function global analysis framework, modifying the underlying theory to allow for the possibility of a dark photon,” said Thomas.

“Our work shows that the dark photon hypothesis is preferred over the standard model hypothesis at a significance of 6.5 sigma, which constitutes evidence for a particle discovery.”

This is not the end of the story, and much more research will need to be done to confirm that the dark photon hypothesis is in fact the right one.

But the team is already thinking about more analysis to make the sigma even stronger.

“We plan to also implement different heavy quark scheme for the discussion of charm and bottom quark production data,” the researchers write in their new paper.

“The most important improvement would, however, be direct searches in the mass region suggested by our analysis.”