What next after finding the goddamn Higgs boson particle?

14 July 2022

The Large Hadron Collider (LHC) is being fired up again after an extensive upgrade, and expectations are high the revamped particle collider will yield further of the universe’s secrets. Australian journalist Sherryn Groch has written about what scientists hope to learn in the next round of LHC experiments, as part of the Sydney Morning Herald Explainer series of articles.

For many people the LHC is most notable for finally confirming the existence of the elusive Higgs boson, nicknamed the goddamn particle by some scientists, on account of the difficulty they had finding it. The discovery though wasn’t quite the missing piece of the puzzle physicists expected it to be, says Dr Mitesh Patel, a lead researcher at CERN, giving rise to the possibility a fifth force of nature may exist, over and above the presently accepted four.

And then there’s the Higgs boson itself: it’s much lighter than expected. “It doesn’t really make sense on its own,” Patel says. “Everything about it tells us its mass should be much heavier. So, is something keeping it low? That’s what makes us think there’s something else.”

But the plot thickens. Shortly before the LHC was deactivated for upgrade, Patel and his team were struggling to make sense of data they had gleaned from older LHC experiments. What they were seeing didn’t stack up against the tenets of the Standard Model of physics, used to account for the four forces of nature, being electromagnetism, the weak force, the strong force, and gravity, even if the Standard Model does not actually explain gravity.

In the subatomic realm, particles interact and change all the time. And, according to the standard model, those known as beauty quarks should decay as often into muons as they do into electrons. But on the CERN team’s measurements, they became electrons 15 per cent more often than the muons, suggesting something could be tipping the scales.

Scientists are hoping further LHC experiments will also tell them more about dark matter, which coupled with dark energy, makes up ninety-five percent of the universe. But gravity remains the mystery. Standard Model does not account for it, and scientists are puzzled as to why it is far weaker than the other forces of nature. But they have some mind-boggling suggestions as to why:

[Some] speculate whether dark matter is really the effects of matter in another universe – gravity leaking through a multiverse into our own. It sounds like a Marvel film but Patel says “there are decent foundations” for the theory, namely that scientists still don’t understand why gravity is so much weaker than the other three forces of nature. “So people have speculated that maybe gravity behaves differently because it’s spread out in other dimensions in addition to our own”.

It is possible insights into these puzzles may be forthcoming sooner rather than later, once the LHC is up and running again. This I am looking forward to.