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Dreams of physicists: which colliders would be steeper than the Big Hadron?

If elementary particle physicists succeed,New accelerators will one day be able to carefully explore the most curious subatomic particle in physics - the Higgs boson. Six years after the discovery of this particle at the Large Hadron Collider, physicists are planning new huge machines that will stretch tens of kilometers in Europe, Japan or China.

New Colliders: What Will They Be?

Discovery of this subatomic particle whichreveals the origin of mass, led to the completion of the Standard Model - a comprehensive theory of elementary particle physics. And it also became a landmark achievement for the LHC, currently the world's largest accelerator - after all, it was to search for the Higgs boson, although it was not only built.

Now physicists want to delve into the secrets of the bosonHiggs in the hope that he will be the key to solving the long-running problems of particle physics. "The Higgs is a special particle," says physicist Ifang Wang, director of the Institute for High Energy Physics in Beijing. "We believe that Higgs is a window to the future."

The Large Hadron Collider, aka BAK, consistingfrom a ring 27 kilometers long, inside which the protons accelerate almost to the speed of light and collide billions of times per second, has almost reached the limit of its capabilities. He did an excellent job with the Higgs detection, but is not suitable for his detailed research.

Therefore, elementary particle physicists require newparticle collider, specially designed to launch piles of Higgs bosons. Several projects have been proposed for these powerful new machines, and scientists hope that these Higgs factories could help find solutions to the glaring weaknesses of the Standard Model.

"The standard model is not a complete theorythe universe, ”says particle physics experimenter Galina Abramovich from Tel Aviv University. For example, this theory does not explain dark matter, an unidentified substance, the mass of which is necessary to account for cosmic observations, such as the movements of stars in galaxies. It also does not explain why the Universe consists of matter, while antimatter is extremely rare.

Supporters of new colliders claim thata thorough study of the Higgs boson can lead scientists to solve these mysteries. But among scientists, the desire for new high-priced accelerators is not supported by all. In addition, it is not clear what exactly could find such machines.

Next in line

The first in line is the International LinearCollider in the north of Japan. In contrast to the LHC, on which particles move in a ring, the MLK accelerates two particle beams in a straight line, directly at each other, along its entire 20-kilometer length. And instead of pushing protons together, he pushes electrons and their antimatter partners, positrons.

However, in December 2018, interdisciplinaryThe committee of the Scientific Council of Japan opposed this project, urging the government to be careful with its support and wondering if the expected scientific achievements justify the cost of the collider, which is currently valued at $ 5 billion.

Supporters argue that the MLK plan forThe collision of electrons and positrons, rather than protons, has a number of major advantages. Electrons and positrons are elementary particles, that is, they have no smaller components, and protons consist of smaller particles - quarks. This means that proton collisions will be more erratic and create more useless particle debris that will have to be sifted.

In addition, in proton collisions onlySome of the energy of each proton actually falls into a collision, while in an electron-positron collider, particles transfer total energy to a collision. This means that scientists can adjust collision energy to maximize the number of Higgs bosons produced. At the same time, the MLK will require only 250 billion electron volts to produce the Higgs bosons, compared with 13 trillion electron volts at the LHC.

At MLK, “the quality of the data received will be muchabove, ”says Lin Evans, elementary particle physicist from the Geneva CERN. One out of every 100 collisions on the MLK will produce the Higgs boson, whereas at the LHC it happens every 10 billion collisions.

The Japanese government is expected to takethe decision on the collider in March. Evans says that if MLK is approved, it will take about 12 years to create. Later, the accelerator can also be upgraded to increase the energy it can achieve.

CERN has plans to create a similar machine -Compact Linear Collider (CLIC). It will also collide electrons and positrons, but at higher energies than MLK. Its energy will start from 380 billion electron volts and increase to 3 trillion electron volts in a series of upgrades. In order to achieve these higher energies, it is necessary to develop a new particle acceleration technology, which means CLIC will obviously not appear before the MLK, says Evans, who heads the collaboration between the researchers of both projects.

Circle running

Two other planned colliders in China andEurope, will be round, like the LHC, but much more: each circle is 100 kilometers. This is a big enough circle to double the country of Liechtenstein. This is practically the length of the Moscow Ring Road.

Circular electron-positron collider, placethe construction of which in China has not yet been determined, will push electrons and positrons into 240 billion electron volts, according to a conceptual plan officially presented in November and protected by Van and the Institute of High Energy Physics. This accelerator can later be upgraded to push protons at high energies. Scientists say they could start building this machine, worth $ 5-6 billion by 2022, and complete it by 2030.

And at CERN the proposed Future Circularthe collider, the BKK, will also come into operation in stages, colliding electrons with positrons, and later protons. The ultimate goal will be to achieve proton collisions at 100 trillion electron-volts, which is more than seven times the energy of the LHC.

Meanwhile, scientists closed the BAC for two years,upgrading the machine to work at a higher energy. In 2026, a high luminosity BAC will work, which will increase the frequency of proton collisions at least five times.

Higgs portrait

When the LHC was built, scientists were sufficientsure to find the Higgs boson with it. But with new cars it is not clear what new particles to look for. They will simply catalog how much the Higgs interacts with other known particles.

Higgs interaction measurements can confirmStandby model expectations. But if the observations are different from the expectations, the discrepancy may indirectly indicate the presence of something new, such as particles that make up dark matter.

Some scientists hope something happens.unexpected. Because the Higgs boson itself is a mystery: these particles condense into a liquid, similar to molasses. Why? We have no idea, says particle physicist Michael Peskin of Stanford University. This fluid permeates the universe, slowing down the particles and giving them weight.

Another mystery is that the massHiggs a million billion less than expected. This oddity may indicate that there are other particles. Previously, scientists thought that they would be able to respond to Higgs problems using supersymmetry theory - a consonant that every particle has a heavier partner. But this did not happen, because the LHC did not find any traces of supersymmetric particles.

Future colliders may still findevidence of supersymmetry or otherwise hint at new particles, but this time scientists will not make promises. Now they are more busy developing priorities and bringing arguments in favor of new colliders and other experiments in particle physics. One thing is certain: the proposed accelerators will explore unknown territory with unpredictable results.

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