NEWS
NORMAN, OKLA. – Beneath the visible fabric of our universe lies a world of unanswered questions, and one theory might tie them all together. Supersymmetry, an extension of particle physics, could explain both the elusive nature of dark matter and the possibility of a multiverse. At the forefront of this research is University of Oklahoma physicist Howard Baer, who has spent decades exploring how these invisible forces may unlock the next level of physics.
In 2012, scientists at CERN made headlines by discovering the Higgs boson, commonly called the “God particle,” using the Large Hadron Collider (LHC) in Geneva, Switzerland. This breakthrough confirmed the existence of the Higgs field, a mysterious energy field that gives particles their mass. But there’s a problem: according to the math, the Higgs boson should be far heavier than it is. Something hidden must be keeping it light.
The Theory of Everything
Supersymmetry could be the key to solving why the Higgs boson is so light. The theory suggests that every known particle has a hidden superpartner, a kind of mirror image that counterbalances the quantum forces threatening to make the Higgs particle far too massive. For every known particle that pushes up the Higgs mass, a superpartner pulls it back down.
Yet after years of high-energy collisions at the LHC, no superpartners have been detected. As reported in Scientific American, this ongoing absence has led some physicists to question whether supersymmetry exists at all, or if it simply lies just beyond our current reach.
“Here at OU, we’ve been leading work on a concept called naturalness, which is about figuring out how the universe's laws stay stable without needing a lot of fine-tuning. We've also been exploring something in string theory called the landscape, which suggests there could be many different possible versions of physics, each with different particle masses,” Baer said. “From that perspective, it makes sense that the LHC hasn’t found light supersymmetric particles. Instead, it might mean those particles are just heavier than we originally expected—and that’s exactly what our work suggests.”
According to Baer, supersymmetry offers an avenue to solve issues that make that Standard Model of physics mathematically unstable. By unifying separate forces and particles into one elegant system, supersymmetry brings much-needed stability to the math behind the universe.
“For example, gravity is not included in the quantum laws of physics. But there’s a version of supersymmetry called supergravity, which does include gravity,” he said. “Supergravity is part of string theory, which could be the master blueprint that combines quantum physics and gravity. If this is correct, it would give us a much more complete understanding of the universe.”
Explaining Dark Matter
According to Baer, astronomers know that the universe is filled with dark matter, which has mass and gravity, but doesn’t emit light or energy. NASA estimates that dark matter accounts for 27% of all matter in our universe, while dark energy makes up a staggering 68%.
“You can’t see dark matter, you can only see its gravitational effects,” Baer said. “Supersymmetry predicts the existence of new particles and two of them are excellent candidates for dark matter. So, the fact that supersymmetry includes dark matter particles makes it an excellent fit for a unified scheme.”
Baer recently published a new theory on how dark matter is composed of two distinct particles: WIMPs and axions. WIMPs, or weakly interacting massive particles, are a form of classic dark matter. They’re massive, invisible and only weakly affected by other forces. Axions are very light, ghost-like particles that are extremely hard to detect. In Baer’s new theory, WIMPs decay away in the early universe, leaving only axions to make up today’s dark matter. Detecting the remnant axions is a problem, however, because detector sensitivity isn’t advanced enough.
“The best WIMP search experiment right now is located a mile underground in the old Homestake Gold Mine in South Dakota,” he said. “It’s looking for leftover WIMPs from the Big Bang. They haven’t found any so far, which is consistent with the idea of them decaying away in the early universe.”
Proof of a Multiverse?
Baer, who has been studying supersymmetry since 1985, has published nearly 400 papers and a textbook on the subject and even spent time working at CERN. When the Higgs boson was discovered in 2012, he found that earlier methods for measuring whether supersymmetry was “natural” were flawed. He introduced a more accurate approach to evaluate whether supersymmetry truly fits within the framework of modern physics.
“In string theory, there could be around 10^500 (that’s a 1 followed by 500 zeros) vacua, or different ways the laws of physics could play out. This idea supports the idea that our universe being one out of a boiling froth of multiverse vacua,” he said. “So, we found a way to calculate how supersymmetry might be revealed from the landscape of string vacua. The results suggest that if supersymmetry particles exist, they would be too heavy to have already been detected by the LHC. But they may be revealed by additional LHC data which is expected to accrue over the next decade.”
Since supersymmetry has yet to be discovered, some funding agencies have begun to turn their backs on supersymmetry, declaring the theory outdated or even dead. Baer strongly disagrees, arguing that the search is far from over.
“We’re not ready to abandon supersymmetry,” he said. “As Galileo once argued, in matters of science, the reasoning of a single individual can outweigh the opinions of thousands. We’re convinced that supersymmetry is essential to unifying the laws of physics.”
Looking forward, Baer is optimistic that the High-Luminosity upgrade to CERN’s LHC could help uncover supersymmetry particles.
“We’re hoping it can eke out the tip of the supersymmetry iceberg. If so, it would open up a whole new superworld of physics lurking beneath the surface, just waiting to be explored,” he said.
About the research
Baer is the Homer L. Dodge Professor of High Energy Physics and George Lynn Cross Research Professor in OU Homer L. Dodge Department of Physics and Astronomy. His research focuses on theoretical particle physics and cosmology, in phenomenology where theory and experiment intersect.
About the University of Oklahoma
Founded in 1890, the University of Oklahoma is a public research university located in Norman, Oklahoma. As the state’s flagship university, OU serves the educational, cultural, economic and health care needs of the state, region and nation. For more information about the university, visit www.ou.edu.
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