The detection of the Higgs boson at CERN in 2012 is one of the biggest scientific discoveries of the decade. In the years since, scientists have been carefully measuring its properties, and now the ATLAS and CMS Collaborations have made the most precise measurement of its mass to date.
The Higgs boson is an incredibly important particle – for one, it was the final elementary particle predicted by the Standard Model of particle physics. The boson represents the Higgs field, which uniformly pervades the entire universe. Other fundamental particles, such as quarks and leptons, gain their mass by interacting with the Higgs field.
The hypothesis was first proposed back in the 1960s, but the Higgs boson wasn’t directly detected until 2012, finally confirming the mechanism. That earned the scientists who originally proposed the idea the 2013 Nobel Prize in Physics.
At the time it was first detected, the mass of the Higgs boson was measured as roughly 125 to 126 Gigaelectronvolts (GeV). And now that figure has been refined further, to an uncertainty of within 0.1 percent. According to the team, the Higgs boson has a mass of 125.35 GeV.
This new result is based on data gathered at the Large Hadron Collider between 2011 and 2016. The Higgs boson is unstable, and usually decays into lighter particles extremely quickly. In 2011 and 2012, the CMS detector observed the Higgs boson decaying into two Z bosons, before then further decaying into four leptons. In 2016, it was observed decaying into two photons.
The researchers combined these results to arrive at the new mass measurement, which is the most precise ever taken.
While the team says that the new measurement itself won’t directly lead to new physics, it does add more pieces to the puzzle of the Higgs boson and the limits of the Standard Model. Understanding the mass helps improve future measurements of other properties of the particle, and what we can expect to find in upcoming particle accelerators. Ultimately, the team says, it will help us in “understanding the long-term stability of the universe.”
A detailed summary of the findings was published online at the CMS Collaboration.