The hunt for the source of dark matter is one of the most hotly anticipated searches of our time and the Higgs boson might be able to light the way to a possible dark matter discovery.
Confirmation of a Higgs boson discovery came in 2012 after a multi-decade search. Theorized in the 1960′s, experiments at CERN’s Large Hadron Collider (LHC) near Geneva, Switzerland, decades later confirmed the particle’s decay signature, eventually leading to the 2013 Nobel Prize for Physics being awarded to Peter Higgs and François Englert, two of the key physicists who laid out the theoretical framework for the particle.
As we already know, the Higgs particle mediates the Higgs field, which endows all matter with mass. The discovery of the Higgs boson at the LHC was the last “missing piece” of the Standard Model of physics. The Standard Model governs our understanding of the quantum world; it’s a recipe book of sorts that enables us to understand how subatomic particles and forces interact on the smallest of scales.
However, though the basic framework of the Standard Model works for most of our purposes, it is not an all-encompassing model. Most notably, the Standard Model does not incorporate gravity — obviously a very important omission. Also, the Standard Model does not predict the source of mysterious dark matter — a fact that is growing more contentious by the day.
Cosmological studies predict that 84.5 percent of the universe is composed of matter that can exert a gravitational force and yet does not interact with the electromagnetic force. It is a type of matter — known as non-baryonic matter — that cannot be seen, but its effects become extremely obvious when observing the gravitational effects in galactic clusters, for example. It’s out there, we’re certain of it, but we just can’t see it and therefore cannot fully understand its nature.
There are many theories suggesting different exotic sources of dark matter, but a new model put forward by a team headed by theoretical particle physicist Christoffer Petersson, of Chalmers University of Technology in Sweden, will be tested at the LHC when it is restarted this spring.
Petersson suggests that the Higgs boson may decay in an alternative way than what has been observed to date; a decay path that is governed by supersymmetry.
Supersymmetry predicts that there are more massive “super partners” of known particles that exist beyond the Standard Model framework. Although there have been tantalizing hints of these supersymmetric particles, definitive observational evidence has been frustratingly hard to track down.
But in the LHC’s new phase of operations, where particle collisions will be boosted to record energies, evidence of supersymmetry may be more forthcoming. And this is where the Higgs comes in.
The LHC’s detectors didn’t directly ‘see’ a Higgs boson when it made its discovery. The ATLAS and CMS detectors, over countless billions of particle collisions, slowly built up a picture of post-collision particles that sprayed away from the energy generated after counter-rotating protons smashed into one another. From this collision energy, Higgs boson particles condensed in isolation but rapidly decayed into other particles that the detectors could measure, such as muons (the electron’s more massive cousin). This provided a Higgs ‘fingerprint’ of sorts, evidence that Higgs bosons are being generated.
Now Petersson’s team has suggested that, if supersymmetry is real, the Higgs boson may have another mode of decay, disintegrating into photons and dark matter particles. And the LHC’s ATLAS and CMS experiments are on the look-out for this theorized decay mechanism.
“It’s a dream for a theorist in particle physics. LHC is the only place where the model can be tested, ” said Petersson. “It’s even nicer that two independent experiments are going to do it.
“If the model is found to fit, it would completely change our understanding of the fundamental building blocks of nature. If not, just the fact that they are willing to test my model at CERN is great.”
What is Higgs-boson?
The Higgs boson, or "God Particle", is a hypothetical massive scalar elementary particle predicted to exist by the Standard Model in particle physics.