Three years after discovering the elusive Higgs boson or so-called ‘God particle’, CERN physicists have drawn the sharpest picture yet of this novel particle and found that it behaves just as predicted.
The ATLAS and CMS Collaborations at CERN have presented combined measurements of many of the particle’s properties for the first time.
The new results provide in particular the best precision on its production and decay and on how it interacts with other particles.
All of the measured properties are in agreement with the predictions of the Standard Model and will become the reference for new analyses in the coming months, enabling the search for new physics phenomena, CERN said.
This follows the best measurement of the mass of the Higgs boson, published in May 2015 after a combined analysis by the two collaborations.
“The Higgs boson is a fantastic new tool to test the Standard Model of particle physics and study the Brout-Englert-Higgs mechanism that gives mass to elementary particles,” said CERN Director General Rolf Heuer.
“There is much benefit in combining the results of large experiments to reach the high precision needed for the next breakthrough in our field. By doing so, we achieve what for a single experiment, would have meant running for at least 2 more years,” said Heuer.
There are different ways to produce a Higgs boson, and different ways for a Higgs boson to decay to other particles.
For example, according to the Standard Model, the theory that describes best forces and particles, when a Higgs boson is produced, it should decay immediately in about 58 per cent of cases into a bottom quark and a bottom antiquark.
By combining their results, ATLAS and CMS determined with the best precision to date the rates of the most common decays.
Such precision measurements of decay rates are crucially important as they are directly linked to the strength of the interaction of the Higgs particle with other elementary particles, as well as to their masses, CERN said.
Therefore, the study of its decays is essential in determining the nature of the discovered boson.
Any deviation in the measured rates compared to those predicted by the Standard Model would bring into question the Brout-Englert-Higgs mechanism and possibly open the door to new physics beyond the Standard Model.
“This is a big step forward, both for the mechanics of the combinations and in our measurement precision,” said ATLAS Spokesperson Dave Charlton.
“With such a result and the flow of new data at the new energy level at the LHC, we are in a good position to look at the Higgs boson from every possible angle,” said CMS Spokesperson Tiziano Camporesi.