On July 4, 2012, physicists announced a breakthrough - a subatomic particle was discovered, corresponding in characteristics to the Higgs boson. Using data from two experiments of the Large Hadron Collider - CMS and ATLAS - scientists discovered a particle with energy corresponding to the theory.
“We're seeing a new boson,” proclaimed Joe Incandela , lead physicist at CMS, to the sound of applause at a special meeting in Geneva. Is the last puzzle piece called the Standard Model found? Will the discovery be the beginning of the end of physics as we know it?
A year after this historic day, physicists are still trying to characterize this “new boson," and although it does look like a Higgs boson, can the quantum hunt be considered complete?
In the best traditions of particle physicists, scientists are still working on it.
“Without a doubt, we found out that this is a new particle, and this is a boson. However, we have yet to prove that it is Higgs, ”said physicist Pauline Gagnon of CERN.
Wait a moment. Are we still awaiting “confirmation”?
The Higgs boson is the last piece of the Standard Model, a comprehensive theory that describes the nature of subatomic particles in our universe. Born as part of a theory created by a team of physicists in the 1960s under the leadership of Peter Higgs, the particle has long been the focus of attention on powerful particle accelerators. In particular, 7.5 billion euros were allocated for the construction of the LHC on the Franco-Swiss border specifically to search for the elusive boson.
The constant investment of time, energy and money in the search for a subatomic particle gave rise to the most complex experiment in the history of mankind, and all in order to understand one of the most fundamental puzzles in physics. It is believed that the Higgs boson is an “exchange particle” that gives matter mass; without it, the universe, as we know it, would not exist. In short, for the Standard Model to be true, the Higgs boson must exist. Otherwise, quantum physics would be wrong and a revolution in physics would await us. Physicists are very fond of revolutions in physics, so not all scientists were jubilant when they announced the discovery of the Higgs boson. Many would be comfortable if the Higgs boson did not exist.
Since the high-profile announcement of last year, the complex problem of characterizing a candidate particle has kept LHC physicists in constant tension. Although there is a boson at the energy level predicted for the Higgs boson, it may not be the Higgs boson. Some physicists support the idea of the existence of only one type of Higgs boson, while proponents of the theory of superstrings number at least five.
“Have we found the right boson, or just one of several predicted by other theories? Until today, everything indicated that this boson belongs to the Standard Model, ”says Gagnon. “He looks, sings, smells and dances like the Higgs boson.”
Indeed, almost immediately after the discovery of the "new boson", physicists had to work on understanding the other physical characteristics of the particle. To be a Higgs boson, a particle must have zero spin and have positive parity. Spin is a quantum measure of angular momentum, and parity is a measure of how a specularly reflected particle behaves. After analyzing the data, the amount of which is 2.5 times higher than last year, in March, physicists announced that the Higgs candidate “has no spin and is positively even”. So far, so good.
As the analysis goes, the boson is really Higgs. However, some physicists do not exclude the possibility that nature leads them by the nose, while others are confident that we can never say that Higgs is the only one.
“I'm not sure that one day someone will say that this is the Higgs boson from the Standard Model,” says Bill Murray, ATLAS experiment coordinator. “We can never say that he is alone, because there can always be another, so heavy that you cannot even ... make him.”
It is possible that even the LHC is not able to accelerate protons to such a speed and give so much energy that a true Higgs boson will be born as a result of the collision.
Therefore, physicists will work hard to make sure that nature does not play tricky games with them and does not spoil the purity of experimental results.
“You can never prove that something is true, you can only prove that it is not true,” says Murray. “All we can do is eliminate the maximum of alternatives.”
Well, a lot of work remains to be done by the International Linear Collider, which was recently introduced.
The article is based on materials .
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