Scientists may have seen dark matter. If they did, what exactly is it?

If a recent hint of dark matter is real, it would rewrite physics. Scientists are already trying to read the outline of that new story’s plot. And that’s reignited interest in certain theories, including a long-beloved but increasingly sidelined concept called supersymmetry.

Dark matter is imperceptibly everywhere, an unidentified type of particle pervading the universe but evident based only on its gravitational effects on galaxies and other cosmic entities. On September 1, scientists with the LUX-ZEPLIN, or LZ, collaboration announced they’d seen a signal in their detector that could have been caused by a single particle of dark matter — though it could still be just a blip caused by known physics processes. In the weeks since the detection, dozens of papers have been posted on arXiv.org purporting to explain what LZ saw.

Much interest has focused on a theorized type of particle called a higgsino. If the idea is correct, it would be big. Supersymmetry proposes that for each known particle, there exists a heavier counterpart called a superpartner.

It’s an idea that could solve multiple physics puzzles at once, so it has attracted a devoted following of physicists. One of these hypothetical superpartners, such as the higgsino, could be dark matter. The higgsino is the superpartner of the Higgs boson — a particle discovered in 2012 that explains the origin of mass.

In recent years, supersymmetry’s popularity has waned, as particle colliders failed to find evidence for it. But as an explanation for LZ’s dark matter hint, a higgsino seems plausible — at least at first glance. The LZ detector, located at the Sanford Underground Research Facility in Lead, S.D., consists of a large tank of liquid xenon.

The detector searches for dark matter speeding through the xenon, crashing into it and sending a xenon atomic nucleus zinging away. That’s expected to be a rare event, since dark matter interacts very weakly with normal matter. In the event LZ found, the nucleus recoiled with particularly high energy.