Ten years ago, jubilant physicists working on the world’s most powerful scientific experiment, the Large Hadron Collider (LHC) at CERN, announced the discovery of the Higgs boson — a particle scientists had been searching for since 1964, when its existence first began was predicted.
“For particle physicists, the Higgs boson was the missing piece of the Standard Model,” Victoria Martin, Professor of Particle Physics at the University of Edinburgh in the UK, told Space.com.
Although the Large Hadron ColliderThe scope of is far-reaching, the search for the Higgs boson was the top priority when it went online in 2010. The two key experiments of the LHC – ATLAS (A Toroidal LHC Apparatus) and CMS (Compact Muon Solenoid) – discovered the Higgs boson within just two years of starting operations.
“We didn’t expect to see the Higgs boson so quickly,” CERN Director General Fabiola Gianotti said during a preview press conference on Thursday (June 30). It was the LHC’s superior computing infrastructure applied to experiments that performed better than their design specifications – a testament to the many years of hard work that went into building the LHC – that accelerated the discovery of the Higgs boson, she said .
Related: 10 Cosmic Mysteries The Large Hadron Collider Could Unravel
Continue reading: Our original coverage of the Higgs discovery
The Mystery of the Crowd
The Higgs boson changed the world of particle physics and opened doors that were closed until its discovery.
“Particle physics has changed more in the last 10 years than in the previous 30 years,” said Gian Giudice, head of CERN’s Department of Theoretical Physics, during the event.
The Higgs boson is important because it carries the force of an energy field known as the Higgs field, much like a photon carries the force of the electromagnetic field.
“The field is more fundamental than the particles,” Martin said. “It permeates all the way through space and time.” It is the interaction between certain particles and the Higgs boson that represents the Higgs field that gives these particles their mass.
An analogy is to think of the Higgs field as a kind of cosmic syrup that slows down some particles more than others. Less massive particles pass through the Higgs field with relative ease and can therefore fly away at the speed of light – imagine that electrons, which have tiny mass, or photons, which have no mass at all. Other particles are slowed down by wading through the cosmic syrup of the Higgs field, giving them more mass, and hence these particles are the most massive.
Like these particles, scientists believe—although they have yet to observe the process—that the Higgs boson gets its mass from interacting with itself. And measurements by the LHC have shown that the Higgs boson also has a high mass: 125 billion electron volts, i.e. about 125 times heavier than one of the positively charged protons in the nucleus of an atom. (Thanks to Einstein’s special theory of relativityParticle physicists know that mass and energy are interchangeable and therefore refer to masses in terms of their energy.) Only one fundamental particle known to science is more massive.
Discovering the Higgs boson and measuring its mass was just the beginning. “We’ve spent the last 10 years testing the Higgs boson because discovering it was one thing, but the Standard Model also tells us many things about how the Higgs boson should behave,” Martin said.
An existential question
For one, the quantum spin of the Higgs boson — or lack thereof — could shed light on why ours universe even exists.
Every known particle has a quantum spin, with the exception of the Higgs boson. The Standard Model of particle physics predicted this oddity, so it’s no surprise, but scientists, including Martin and her research team, have continued trying to measure the spin of the Higgs boson to test the Standard Model. So far they haven’t found any evidence that it has any spin.
The reason why the Higgs boson, unlike all other known particles, has no spin is due to the nature of the Higgs field. Unlike gravitational and electromagnetic fields, which have obvious sources such as an object’s mass or an electric current flowing through magnetic fields, the Higgs field has no source. It’s just there, a non-localized part of the cosmos that permeates everything. As such, it is coupled to the “vacuum,” the very fabric of leisure, and therefore the field shares the properties of the vacuum. The vacuum has no quantum spin and therefore neither does the Higgs boson.
However, the vacuum is not inert. Particles bubble in and out thanks to quantum fluctuations, raising the energy level of the vacuum above its lowest possible state. The thing about energy levels is that an object – be it a person in a gravitational field, an electron orbiting an atomic nucleus, or the vacuum – always prefers to be at the lowest possible energy level. But our universe is not. What keeps the universe from succumbing to the inevitable urge to lower energy levels is the form of what scientists characterize as the energy potential of the Higgs field.
A diagram of this energy potential would look like a “mountain” in the center and two “valleys” flanked by “hills” on either side. The energy level of the vacuum would be in one of these valleys, but physicists strongly suspect that there are even deeper “valleys” on either side of these hills, representing even lower energy states. And measuring the mass of the Higgs boson supports this idea; The particle is so large that it suggests the Higgs field may one day decay to lower energy levels.
This is why physicists call our vacuum a “false” vacuum, because it “wants” to decay to a lower energy – a “more real” vacuum. The valleys and hills of the energy potential of the Higgs field keep our universe in this false vacuum long enough for planets, stars and galaxies to form.
However, over eons upon eons, the false vacuum is inherently unstable and will eventually decay. Perhaps quantum energy fluctuations will allow the false vacuum to climb over these “hills” and roll down the slope on the other side, or perhaps the strange phenomenon of quantum tunneling will allow it to drill through the “hill” that represents the energy barrier.
However it happens, it would be bad for the universe – the Decay of the false vacuum would expand outward in a wave at the speed of light, destroying everything and replacing it with a true vacuum. Only the Higgs field keeps vacuum decay in check, so we have the Higgs field to thank for our present universe.
Another attempt to understand the universe
In addition to the spin of the Higgs boson, researchers have spent the last decade determining its lifetime. The existence of the Higgs boson is fleeting; The Standard Model predicts that a Higgs boson survives just a tiny amount of time, just 10^-22 seconds, before that break apart into more subatomic particles. However, this calculation has not yet been verified experimentally. “It’s so quick,” says Martin.
Physicists hope that the next phase of operation at the LHC will be dubbed run 3 and will serve as a coveted stopwatch from Tuesday (July 5).
“We hope that we can indirectly measure how long the Higgs boson lives,” Martin said. “If we can measure the lifetime, that gives us more constraints on what particles the Higgs boson is lapse into.”
Understanding how the Higgs boson decays into other particles could in turn reveal hidden subatomic particles new to science, perhaps even mysterious particles Dark matter.
Because of these implications, Gianotti described the Higgs boson as a crucial tool to explore the deepest mysteries of particle physics. “The Higgs boson is a very precise microscope to study nature at the smallest scales, and at the same time it is an impressive telescope to access physics at very high energy scales,” she said.
The discovery of the Higgs boson has not only allowed physicists to cross another particle off the list. Its very existence and behavior raise questions about some of the most profound areas of fundamental physics: the structure of matter in the universe, the fate of the universe, whether the universe is stable, and how elemental particles are related to one another.
However, the Higgs boson continues to play with its mysteries. “Everything we’ve seen so far seems to be exactly what the Standard Model predicted,” Martin said. “While this is interesting, it’s also a bit disappointing because we were hoping that the Higgs boson could help us see.” beyond the standard model.”
Far from breaking the rules and destroying physics, it is necessary to go beyond the Standard Model to explain phenomena that don’t fit, such as: B. dark matter, or to open doors to a new physics, such supersymmetry. For this reason, after four years of upgrades, the LHC will once again delve into the mysteries of the Higgs boson.
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