proton secrets. Age and size not yet known

It is well known that there are three quarks in a proton. In fact, its structure is more complicated (1), and the addition of gluons that bind quarks together is not the end of the matter. The proton is considered a veritable sea of ​​quarks and antiquarks coming and going, which is strange for such a stable particle of matter.

Until recently, even the exact size of the proton was unknown. For a long time, physicists had a value of 0,877. femtometer (fm, where the femtometer is equal to 100 quintillion meters). In 2010, an international team conducted a new experiment at the Paul Scherrer Institute in Switzerland and got a slightly lower value of 0,84 fm. In 2017, German physicists, based on their measurements, calculated a proton radius of 0,83 fm and, as expected with the accuracy of the measurement error, it would correspond to the value of 0,84 fm calculated in 2010 based on the exotic "muonic hydrogen radiation."

Two years later, another group of scientists working in the US, Ukraine, Russia, and Armenia, who formed the PRad team at the Jefferson Lab in Virginia, cross-checked the measurements with new experiment on the scattering of protons on electrons. The scientists got the result - 0,831 femtometers. The authors of the Nature paper on this do not believe the problem is completely solved. This is our knowledge of the particle, which is the "basis" of matter.

We clearly say that proton - a stable subatomic particle from the group of baryons with a charge of +1 and a rest mass of approximately 1 unit. Protons and neutrons are nucleons, elements of atomic nuclei. The number of protons in the nucleus of a given atom is equal to its atomic number, which is the basis for ordering the elements in the periodic table. They are the main component of primary cosmic rays. According to the Standard Model, the proton is a complex particle classified as hadrons, or more precisely, baryons. is made up of three quarks – two up “u” and one down “d” quarks bound by the strong force transmitted by gluons.

According to the latest experimental results, if a proton decays, then the average lifetime of this particle exceeds 2,1 · 1029 years. According to the Standard Model, the proton, as the lightest baryon, cannot decay spontaneously. Untested grand unified theories usually predict the decay of the proton with a lifetime of at least 1 x 1036 years. The proton can be converted, for example, in the process of electron capture. This process does not occur spontaneously, but only as a result of provide extra energy. This process is reversible. For example, when parting beta neutron turns into a proton. Free neutrons spontaneously decay (lifetime about 15 minutes), forming a proton.

Recently, experiments have shown that protons and their neighbors are inside the nucleus of an atom. neutrons seem much larger than they should be. Physicists have come up with two competing theories trying to explain this phenomenon, and proponents of each believe the other is wrong. For some reason, protons and neutrons inside heavy nuclei behave as if they were much larger than when they were outside the nucleus. Scientists call it the EMC effect from the European Muon Collaboration, the group that accidentally discovered it. This is a violation of the existing ones.

The researchers suggest that the quarks that make up nucleons interact with other quarks of other protons and neutrons, destroying the walls that separate the particles. Quarks that form one proton i quarks forming another proton, they begin to occupy the same place. This causes protons (or neutrons) to stretch and blur. They grow very strongly, albeit in a very short period of time. However, not all physicists agree with this description of the phenomenon. So it seems that the social life of a proton in an atomic nucleus is no less mysterious than its age and size.