World of Dark Photons

Illustration of two types of long-lived particles decaying into a pair of muons, showing how the signals of the muons can be traced back to the long-lived particle decay point using data from the tracker and muon detectors. Credit: CMS/CERN




This search for exotic long-lived particles looks at the possibility of “dark photon” production, which would occur when a Higgs boson decays into muons displaced in the detector.

The CMS experiment has presented its first search for new physics using data from Run 3 of the Large Hadron Collider. The new study looks at the possibility of “dark photon” production in the decay of Higgs bosons in the detector. 

Dark photons are exotic long-lived particles: “long-lived” because they have an average lifetime of more than a tenth of a billionth of a second – a very long lifetime in terms of particles produced in the LHC – and “exotic” because they are not part of the Standard Model of particle physics.

The Standard Model is the leading theory of the fundamental building blocks of the Universe, but many physics questions remain unanswered, and so searches for phenomena beyond the Standard Model continue. 

CMS’s new result defines more constrained limits on the parameters of the decay of Higgs bosons to dark photons, further narrowing down the area in which physicists can search for them.  READ MORE...

High Energy Scattering Data

Messenger from the dark side: Dark matter may interact with normal matter via a hypothetical particle known as a dark photon. (Courtesy: Shutterstock/80's Child)



A new analysis conducted by an international team of physicists suggests that dark photons – hypothetical particles that carry forces associated with dark matter – could explain certain data from high-energy scattering experiments. The analysis, which was led by,  Nicholas Hunt-Smith and colleagues at the University of Adelaide, Australia, could lead to new insights into the nature of dark matter, which remains a mystery even though standard models of cosmology suggest it makes up around 85% of the universe’s mass.

Dark matter gets its name because it does not absorb, reflect or emit electromagnetic radiation. This makes it extremely difficult to detect in the laboratory, and so far all attempts at doing so have come up empty-handed. “No particle beyond the Standard Model, which describes all the matter with which we are familiar, has ever been seen,” says Anthony Thomas, a physicist at Adelaide and a co-author of the analysis, which is published in the Journal of High Energy Physics. “We have no idea what dark matter is, although it seems likely to be [a] beyond standard model particle (or particles).”
The dark photon hypothesis

Though dark matter is poorly understood, it is nevertheless the leading explanation for why galaxies rotate faster than they should, given the amount of visible matter they contain. But although we can observe dark matter interacting with the universe, the mechanism for these interactions is unclear. According to Carlos Wagner, a particle physicist in the High Energy Physics (HEP) division of Argonne National Laboratory and a professor at the University of Chicago and the Enrico Fermi Institute, dark photons are one possibility.   READ MORE...