Monday, January 30, 2023

The particle that could revolutionize physics

To understand why neutrinos could cause a revolution, we must do some history. In the early 1960s, the situation in theoretical physics was, to put it mildly, chaotic. Particle accelerators spew out new particles every other day; At that time talking about ‘elementary particles’ was a joke. but then it came into play Murray Gell-Mann And in 1962 he announced a way of grouping the particles which he called the “Eightfold Path” in an apparent allusion to Buddhist philosophy. His theory—which was independently formulated by the Israeli Yuval Nieman—launched the field of physics. quark, Since then theoretical physicists have been building a fragile edifice to describe the world of elementary particles. that building gets its name from L standard model of particle physics,

material bricks

The particle that could revolutionize physics

In short, it begins with the hypothesis that there are two main families of elementary particles: quarks and quarks. leptons, Thus the proton and neutron are made of three quarks while the electron is a lepton and not made of any smaller ones. To complicate matters further, it is known that there are six types of quarks and six types of leptons which are grouped in pairs to form three families. Briefly, the Standard Model is composed of the following particles: up and down quarks—which make up the first family—charms and strangenesses, and top and valley quarks.

Leptons, of which there are also six, are grouped as follows: the electron and its neutrino., the muon and its neutrino and the taun with its associated neutrino. Physicists, in a display of imagination, call each of these types a taste Although, in reality, there is little flavor in their names. The matter we see around us is made up of the first family of quarks and leptons: others make up the characteristic particles that are visible in cosmic rays and particle accelerators. from years standard model It was consolidated and only small fragments remain at the beginning of this century.

agony and ecstasy

And then came July 4, 2012, a great moment of glory for particle physics. The particle’s detection was announced at a large-scale press conference at CERN (Geneva), for which it was decided to build the LHC accelerator on a large enough scale: Higgs boson, The party was appropriate because since the discovery of the top quark, particle physicists had gone about 20 years without anything interesting to put in their mouths. Its discovery lends definite support to the Standard Model, as experiments since 2012 are confirming that it has the properties predicted by theory.

Of course, there’s an uneasy visitor in a dark corner of the model that refuses to adapt to that well-constructed theoretical edifice: the neutrino. During the late 20th century, and as experiments with this elusive particle progressed, its role in the Standard Model was taking shape: it is the only physical particle with zero mass; is absolutely three types of neutrinos -Electronic, muonic and tonic-; And neutrinos and their corresponding antiparticles are different, distinguished by a feature called helicity – a version of what happens in our everyday world to the right (right-handed) or left (left-handed). Occurs in -: All types of neutrinos are left-handed and their antineutrinos are right-handed. This is a permanent property and cannot change (a neutrino cannot be right-handed) because its rest mass is zero.


Everything was going well until the 1960s ray davisFrom Brookhaven National Laboratory (USA), came the idea to study neutrinos produced in the Sun nuclear fusion reactions, Every time four hydrogen nuclei convert into one helium, two neutrinos are produced, which immediately escape into space. The amount of neutrinos available is actually enormous: the Sun produces over 200 trillion trillion trillion per second. But since they are so difficult to detect, Davis had to fill a tank with 600 tonnes of perchlorethylene – a compound used in dry cleaning – and buried it under several tonnes of rock; Thus it was protected from any external influences such as cosmic rays. In 1968 there was a surprise: Davis detected only a third of the neutrinos predicted by the theory. Thus was born what has since been known as the “solar neutrino problem”. What was going on in the Sun?

neutrino suit changes

bruno pontecorvobruno pontecorvo

Curiously, the solution was provided in 1957 by an Italian physicist bruno pontecorvo, Seven years earlier, on August 31, 1950, while on vacation in Italy, he suddenly visited Stockholm with his wife and children. The next day KGB agents helped him enter the Soviet Union through Finland, where he was greeted with honor. In the USSR they enjoyed privileges that were reserved for the supposedly socialist and egalitarian society nomenclature, Highest ranking officer.

Pontecorvo proved to have an incomparable physical intuition, especially in the field of neutrinos. In other great ideas, Pontecorvo suggested that they could change suit and become another type of neutrino, a phenomenon known as the neutrino. neutrino oscillation, Nuclear reactions inside the Sun produce neutrinos electronics, so Davis’ team explored only that type. But what if on its way to Earth it changes, becoming one of the other two? This was the only possible explanation, but it needed to be demonstrated experimentally.

It came from the hands of Japanese physicist in 1998 takaki kajitaWhen cosmic rays hit the Earth’s atmosphere, the muon neutrinos that produce the ‘change suit’ oscillate before reaching a detector placed under Mount Kamioka in Japan. This was the experimental confirmation everyone had been waiting for. Neutrinos are going to tell us where future particle physics may move”, commented with satisfaction José Bernabeu at the time, head of the Corpuscular Physics Institute and one of the leading experts on neutrinos in Spain; it was not in vain that he don Earned the nickname Neutrino.

a solution and a problem

Neutrino oscillations are a kick in the stomach to the Standard Model because it requires that neutrinos must have mass (indeed, they do so with a frequency that is proportional to their mass) and the theory states that they do not. . Physics concha gonzalez-garciaOne of the world’s leading experts in neutrino theory, professor at the Institute of Corpuscular Physics in Valencia and ICRAA at Stony Brook University in New York, has stated bluntly: “We are about to discover a new physics.” What about the standard model? No one knows for sure, but this much is certain that this nearly undetectable particle is going to tell us where the very small future of physics might be headed. In fact, it is yet to be decided whether or not neutrinos type dirac (a particle and its antiparticle are different things) or of majorana type (The particle is its antimatter). The most fascinating thing is that no physical particles of the Majrona type have been found. Would it be a neutrino?

Nation World News Desk
Nation World News Desk
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