CERN points giant magnet at the Sun to look for dark matter particles

Axions don’t show up yet, but that doesn’t mean they’re not out there.

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With the identification of the Higgs boson at CERN’s Large Hadron Collider, scientists put the last piece of the Standard Model of physics in place. What they haven’t found is any hint of something beyond the Standard Model. And that hasn’t been for lack of trying. Supersymmetry, the most popular extension to the Standard Model, predicts a large collection of additional particles. We’ve looked for them and, so far, they have not shown up.

But some extensions of the Standard Model don’t predict the sorts of heavy particles that the LHC is designed to identify. Instead, they suggest there’s a very light force-carrying particle called an axion. With the right properties, an axion could solve issues in everything from particle interactions up to the scale of galaxy clusters. But its tiny mass and odd behavior means it won’t be detected in the LHC.

But that doesn’t mean the LHC’s hardware can’t find it. Clever engineers at CERN took magnets originally designed for the LHC, combined them with X-ray focusing technology originally designed for space, and built a device that could spot axions arriving here from the Sun. So far, it has seen no sign of them, which places some strict limits on the properties of these hypothetical particles.

Putting limits on our imagination

Physicists don’t just come up with hypothetical particles for fun. (Well, they might enjoy doing it, but it’s not solely for fun.) They prefer their particles to be what they call “well motivated,” meaning there’s a good reason for proposing them. In the case of axions, that motivation came from quantum chromodynamics, which describes the interactions of quarks and gluons. Axions were proposed to provide a theoretical explanation for why these particles appear to be indifferent to the direction of time (technically called “time-reversal invariance”).

Since then, other types of axions have been proposed, but they all share a critical property: they have mass (although not very much). This makes them possible dark matter candidates, since they should be present in our Universe in very large numbers. (Click to Article)

NA64 hunts the mysterious dark photon – CERN Is Looking For “Dark Interactions” Between Our Side Of The Multiverse And ABADDON ASCENDING Invisible World

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One of the biggest puzzles in physics is that eighty-five percent of the matter in our universe is “dark”: it does not interact with the photons of the conventional electromagnetic force and is therefore invisible to our eyes and telescopes. Although the composition and origin of dark matter are a mystery, we know it exists because astronomers observe its gravitational pull on ordinary visible matter such as stars and galaxies.

Some theories suggest that, in addition to gravity, could interact with visible matter through a new force, which has so far escaped detection. Just as the is carried by the photon, this dark force is thought to be transmitted by a particle called “dark” photon which is predicted to act as a mediator between visible and dark matter.

“To use a metaphor, an otherwise impossible dialogue between two people not speaking the same language (visible and dark matter) can be enabled by a mediator (the ), who understands one language and speaks the other one,” explains Sergei Gninenko, spokesperson for the NA64 collaboration.

CERN’s NA64 experiment looks for signatures of this visible-dark interaction using a simple but powerful physics concept: the conservation of energy. A beam of electrons, whose initial energy is known very precisely, is aimed at a detector. Interactions between incoming electrons and atomic nuclei in the detector produce visible photons. The energy of these photons is measured and it should be equivalent to that of the electrons. However, if the dark photons exist, they will escape the detector and carry away a large fraction of the initial electron energy. (Click to Article)