Scientists have learned a lot about the Higgs boson in the decade since they discovered it. But intriguing questions remain.
When the news came, on July 4, 2012, it moved some scientists to tears. Others jumped and cheered. After decades of anticipation, physicists had at last discovered the Higgs boson.
In the years since that initial detection, physicists have become more and more familiar with this fundamental, force-carrying particle that is produced by the invisible field that gives particles mass. They’ve improved measurements of the Higgs boson’s mass, width, spin, couplings to different particles and other characteristics. They’ve gotten more precise measurements than they expected to be able to make.
Yet there’s still a lot to learn. Most measurements of the Higgs haven’t yet reached the precision scientists need to differentiate between models that could lead to new insights and discoveries. Some aspects of the Higgs boson haven’t even been probed yet.
Today, physicists are continuing to refine their measurements—and even develop ideas for future colliders—in order to fully unveil the mysteries of the Higgs boson and its place in the universe.
1. Does the Higgs boson interact with itself?
One of the biggest questions about the Higgs is how it might interact, or couple, with itself.
Experiments have shown the Higgs couples with other particles, including a menagerie of fundamental particles like the W and Z bosons, quarks, taus and muons. According to the Standard Model, it’s also expected to couple with itself. Uncovering the exact details of how this happens could help physicists further refine the Standard Model, and even shed light on the evolution of the early universe and the matter and antimatter imbalance.
2. How does the Higgs couple to other particles?
While physicists don’t yet know if the Higgs couples to itself, they do know it couples to other particles. In some cases—as with the top quark, the heaviest of the Standard Model particles—the coupling is quite well understood. But physicists are just starting to get a handle on how much other particles, like the comparatively lighter muon, interact with Higgs bosons.
How much a given particle will couple with a Higgs is predicted by the Standard Model and is related to the particle’s mass: The more massive the particle, the greater the coupling. So far, measurements of couplings match these predictions. But the precision of these measurements isn’t yet great enough to see if there could be any deviations from the Standard Model. Knowing exactly how the Higgs couples can help scientists understand how particles get their mass.
3. Are there other Higgs particles?
So far, physicists have found only one Higgs boson, which is what the Standard Model predicts. But some alternative theories that extend the Standard Model call for many more types of Higgs particles.
“There is no reason why there shouldn’t be more,” says Sally Dawson, a theoretical particle physicist at Brookhaven National Laboratory. “There’s a whole host of possibilities on what that could look like.”
4. Is the Higgs connected to dark matter or other unusual particles?
Because the Higgs boson helps explain where mass comes from, many scientists think it should interact with dark matter: the mysterious substance that seems to be connected with everyday matter only through gravity.
“The Higgs could be the portal between us and this dark sector that could hide dark matter,” Gonzalez Suarez says.
Certain theories predict that dark matter interacts with normal matter by swapping Higgs bosons. If this is the case, then a collision that produces Higgs particles could also create dark matter particles.
Fascinating research into the fundamental aspects of our universe! If past trends in physics and cosmological discoveries are any indication, we can expect that new findings will uncover further evidence of fine-tuning within our universe.
Complete article at Symmetry.