The machine that found the Higgs boson in 2012 will be ready for a new season this summer, after three and a half years of upgrades.
“I think we will find another Higgs boson, a lighter one, and more specifically a heavy 96 Gigaelectronvolt,” says theoretical physicist Ari Racliffe, who is open to betting, if anyone wants to bet against it.
GeV stands for Gigaelectronvolt and is a practical unit of mass for small elementary particles.
We’re back at a potential new Higgs boson, but first with a very small look at the mechanism.
A camera the size of an apartment building
The LHC particle accelerator, the Large Hadron Collider, is located in a 27-kilometre-long tunnel annular on the border between Switzerland and France, just outside Geneva, where the CERN research center is located.
In the tunnel, microparticles, mostly protons, but in some periods also lead nuclei, rotate in two directions. Four places along the annulus intersect between two beams of particles, so that the particles can collide.
Equipment that can detect what happens in collisions is called detectors. It’s the size of an apartment building and works somewhat like a very large, fast camera.
Both the accelerator and detectors have been upgraded so that the particles’ velocity increases slightly, from a collision energy of 13 TeV to 13.6 TeV. Thus, the machine can make particles that are slightly heavier than before.
Multiple collisions to find rarities
– But the most important thing is that we could have a lot more collisions than there have been so far, says Racliffe, who works at the University of Oslo.
What the researchers have looked for so far, he says, are the drooping fruits, which are things that were easy to verify.
Some simple things weren’t there, so now experiments are looking for more difficult things, he says.
And if you’re going to find tricky stuff with a particle accelerator, you need a lot of data to comb through.
The experiments will both look for things that rarely happen and tune in to the particles we already know about, he says.
Examines unknown aspects of the Higgs boson
The most exciting particle is the newest member of the family, the Higgs boson.
There’s a lot we don’t know about the Higgs boson, and it has a central place in the Standard Model, the theory that describes elementary particles and the forces that act between them. It’s like an octopus, says Racliffe, with tentacles all over the place between other molecules.
By interacting with the Higgs boson, other elementary particles gain mass. Or was it not that simple?
When Higgs bosons are made in particle collisions on CERN, there are only a tiny fraction of a moment before they transform into other particles. The process is happening so fast that we can’t see the Higgs boson directly, we only see the particles that transformed into it.
Elementary particles are roughly divided into two types: particles of matter, the basic building blocks such as electrons and quarks within the nucleus of an atom; and the strength of a particle, such as the photon lattice, that transmits the electromagnetic force.
As if that weren’t enough, there are three copies of each particle of matter. The electron, for example, has two heavier versions, the muon and the chord. Why there are exactly three editions and why they are so heavy is still unknown.
We have only seen how the Higgs boson turns into particles of energy and the heaviest particles of matter. It may seem a curiosity to particle physicists, but it is important to say whether the Higgs boson gives mass to particles of light matter. It’s an open question, says Racliffe.
Whether the Higgs boson gives mass to particles of light, we can find out by seeing that it transforms into these particles. The Higgs particles that have become two tether particles have already been observed in LHC experiments.
Converting higgs into muons we can see with more data about the LHC, but not into electrons. Racliffe explains that the lighter the particles, the less they interact, and then this happens more often.
The second biggest contradiction in science between theory and experiment
The Higgs boson also hides a number of other mysteries. Perhaps the biggest reason is that the Higgs particle is very light.
The mass of the Higgs particle must be 16 times greater. We don’t understand why this is so easy, says Racliffe.
This was the reason why some physicists did not believe it was possible to find the Higgs boson at the Large Hadron Collider. Stephen Hawking was one of them. He lost $100 in a bet.
High mass prediction is the second biggest contradiction in science between theory and measurement. The largest constant was the cosmological constant, varying by 30 orders of magnitude, says Racliffe.
Promising cracks in the theory
Particle scientists stick to a solid theory that repeatedly predicts experimental results with almost astonishing accuracy. However, the researchers’ biggest desire is to find gaps in the theory with the somewhat unimaginative name of the Standard Model.
Researchers have already noticed several signs of cracks in the theory. In April this year, Fermilab in the United States published a new and very accurate report Measurement of the mass of the boson Wone of two particles that control the fusion of atomic nuclei, radioactivity and make the sun shine.
In the new measurement, the W boson is a little too heavy to agree with the theory.
– If W is really heavier, something must happen that breaks the Standard Model, although we don’t quite know what, says Racliffe.
One year ago, another experiment at Fermilab showed that The muon did not rotate quite as the theory predicted.
Dark matter may be to blame
There is a relationship between muon rotation and W which is probably heavier than assumed. The same phenomenon – the same types of particles – can cause both.
Supersymmetry is a possible candidate. It always is! This is one of the advantages of supersymmetry, says Racliffe, known as a sworn booster.
Supersymmetry is a bag term for a number of theories in which all elementary particles that we know of have a hitherto undiscovered partner; Matter particles have a brother force and force particles have a sister matter. Such models can explain many current problems in theoretical physics, including what dark matter is.
Extra light Higgs boson
There may also be an additional light Higgs boson that we haven’t found yet, which affects both the mass of the W-boson and the muon spinning ring, says Racliffe.
– I think there is another Higgs boson, a little lighter at 96 GeV. In two to three years, we’ll get tested if there is one, he says.
He doesn’t get the idea out of thin air, there are already some unexplained consequences.
From Cern’s previous large accelerator, there was an excess of collisions with two B quarks. In addition, the CMS experiment recently released an analysis in which they looked for Higgs bosons that became two photons. They also see a bump at 96 GeV.
The large bumps aren’t individually, but can be seen in context, like the Higgs boson can explain both bumps and also help us explain W mass and muon spin, says Racliffe.
Useless knowledge can also be useful
– Can we use this knowledge for something?
Not directly, but it gives us a more complete picture of the universe. And along the way, useful technology is being developed. What is most relevant at the moment, says Racliffe, is the development of new machine-learning techniques for use elsewhere.
Our students take their knowledge with them and continue research and industry and do useful things, he says and points out Analysis conducted by economists from the University of Milan, among others.
Economists have calculated the consequences of building the LHC and found a large social and economic surplus, he points out.
Is there more to find?
Some skeptics have expressed concerns that nothing in nature will be within the reach of the LHC, and that undiscovered particles and mechanisms will occur at energies much higher than those achievable with particle accelerators.
Racliffe isn’t too concerned about this “energy desert”. He believes that there must be something more to invent at lower energies.
First, the Higgs particle is very light. It can’t be solved without something on a lower power scale that explains it. Second, dark matter, it’s hard to imagine that it’s much heavier than what we can reach at the LHC. Besides, we have the matter of matter: if the Big Bang produced matter and matter in equal quantities, and matter and matter annihilated each other, how could a tiny bit of matter survive and create the universe today?
It is difficult, even if not entirely impossible, to imagine that there is nothing else in low power. He believes that the probability of discovering something is very high.
Want better control of particles, matter and forces? Watch this presentation of the Standard Model, prepared by Quanta Magazine:
The article was first published in Titan.uio.no
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