The Science Fiction World of Xueba

Chapter 518 Standard Model

Pang Xuelin smiled slightly and said, "Inert neutrinos!"

Shen Yuan was stunned for a moment, and thoughtfully said: "You mean to use inert neutrinos to produce four-quark and pentaquark materials?"

Pang Xuelin shook his head and said, "Teacher, you should know the CP violation of neutrinos, right?"

Shen Yuan nodded.

Pang Xuelin said: "For a long time, the CP violation phase angle δCP has been one of the key parameters in the study of neutrino oscillations. With the discovery of inert neutrinos, we have been able to accurately measure the CP violation phase in neutrino oscillations. But be aware that we also found CP violations in experiments with kaons and B mesons. In particle physics, a kaon is any of the four mesons with a quantum number called a singular number. In the quark In the model, we know that they contain a strange quark, and an antiquark of an up or down quark, and the kaon, which is a combination of two quarks, can just combine with a three-quark baryon to form a pentaquark particle. Due to the There is an effect of positive and negative quarks canceling each other out, so the existence of this particle does not violate the rules of the Standard Model!"

Shen Yuan opened his eyes wide, and it took a while before he opened his mouth and said: "You mean, use the combination of kaons and baryons to create pentaquark particles, and the precise measurement of neutrino CP destroying the phase angle will measure K for us. The meson CP destroys the phase angle and provides a basis."

Pang Xuelin said with a smile: "More than that, the appearance of inert neutrinos means that our research on dark matter has entered a new stage. Inert neutrinos fill the space around us and have a great impact on the formation of galaxies and material structures in the universe. It plays a very important role. But under normal circumstances, this effect exists, and it is easy to cause some free particles to decay. But if we have a way to shield neutrinos, then we will have a great possibility to create five Quark particles, and then synthesize a new strong interaction material on this basis!"

Shen Yuan frowned and said, "Alin, according to what you said, this should be a new physical theory beyond the standard model, right?"

Pang Xuelin nodded with a smile: "To be precise, this new theory is a new physics building built on the basis of the Standard Model theory."

Shen Yuan looked at Pang Xuelin quietly, his disciple was much more ambitious than he imagined.

He is well aware of how difficult it is to propose a new physics framework based on the Standard Model.

When it comes to the standard model, we have to start with the four basic forces.

There are four basic forces in nature, namely: strong interaction force, weak interaction force, electromagnetic force and universal gravitation.

The main difference is simply two points,

One is that the object of action is different, and the other is that the way of delivery is different.

Gravity acts on particles with mass. Note that this mass is not a static mass, but a dynamic mass, which is M in E=Mc^2, which is equivalent to energy. That is to say, gravity can act on all matter with energy, and all matter in our universe has energy, so gravity acts on all matter.

The electromagnetic force acts on all charged particles, including electrons, quarks, and their composite particles, as well as the W particle that transmits the weak force.

Dark matter does not emit light because it has no charge and does not participate in electromagnetic force.

The strong force acts on all particles with color charge, including quarks and gluons. Quarks form protons and neutrons through the strong force, and the remaining strong force makes protons and neutrons form atomic nuclei. Although the gluon is a strong transmitter, it can also form a gluon ball through strong cohesion.

The weak force acts on all particles with a weak isospin, causing the particles to decay.

Interestingly, the weak force is the only one where parity is not conserved, only left-handed electrons (right-handed positrons), left-handed neutrinos (right-handed antineutrinos, if neutrinos are not Majorana particles ), there is a weak force between left-handed quarks (right-handed antiquarks).

This is the difference between the different objects of the four basic forces, and another difference is the different transmission methods.

Gravity is transmitted through gravitons. Although the theory of quantum gravity has not been confirmed experimentally, according to this theory, gravitons have no rest mass like photons, so they can act to infinity and decay according to the inverse square law.

The strong interaction force is the force acting between hadrons, and it is the strongest of the four known basic forces, and its range of action is within the range of 10^-15m. The strong interaction overcomes the strong repulsive force produced by the electromagnetic force, binding protons and neutrons tightly into atomic nuclei.

The weak force propagates through the W and Z bosons, acting on the proton scale one trillionth of the strength of the electromagnetic force. The weak force conforms to SU(2) symmetry. Both W and Z bosons are vector fields with spin 1.

The weak force and the electromagnetic force are unified at higher energies, collectively called "electroweak interaction". At lower energies, because of the higgs mechanism, the W and Z bosons acquire rest masses, and the weak and electromagnetic forces separate.

The standard model of particle physics was proposed to explain the four basic forces in essence.

In the standard model, there are 13 kinds of gauge particles, which are mediums that transmit strong interactions—8 kinds of gluons, and mediums that transmit weak interactions—intermediate bosons, which are divided into three types: W+, W-, and Z0. The medium that transmits the electromagnetic effect - a kind of photon, and in order to realize the electroweak interaction in the energy range below 250Gev, it is decomposed into the electromagnetic interaction and the special particle of the weak interaction - the Higgs particle.

There are three kinds of quarks, which can be divided into up quark and down quark according to different flavors; charm quark and strange quark; bottom quark and top quark. According to different colors, they can be divided into three colors: red, green and blue. Quarks have six flavors. Each taste has three colors, plus their corresponding antiparticles, a total of 36 different states of quarks.

Plus lepton, electron e, muon, tauon, and their respective neutrinos and their antiparticles, there are twelve kinds in total.

This is the 61 kinds of elementary particles shown in the standard particle model.

So far, the results of almost all experiments on the above three forces are in line with the predictions of this theory. Before the 61 kinds of particles predicted by the standard model, W boson, Z boson, gluon, top quark and charm quark have not been discovered, the standard model has predicted their existence, and the estimation of their properties is very accurate.

However, despite its strong predictive power, the Standard Model fails to answer five key questions.

The first question, why do neutrinos have mass?

The three particles in the Standard Model are different types of neutrinos. The Standard Model predicts that, like photons, neutrinos should be massless.

However, scientists have discovered that the three neutrinos oscillate, or interconvert, as they move. This feat is possible only because neutrinos have rest mass.

However, this question can already be answered after the discovery of the inertial neutrino.

The second question is, what is dark matter?

When astronomers observed the rotation of galaxies, they found that the galaxies were spinning much faster than they had theorized, but according to the gravity of visible matter, the galaxies were spinning so fast that they should be tearing themselves apart.

The only explanation, then, is that there is something invisible to us that gives these galaxies extra mass, which creates gravity.

This is dark matter, which is thought to make up 27 percent of the matter in the universe, but it's not included in the Standard Model.

The latest inert neutrino theory proposed by Pang Xuelin will become a strong candidate for dark matter!

The third question, that is why there is so much matter in the universe?

When a particle of matter is formed—for example, in a particle collision at the Large Hadron Collider, or another particle decays—its antimatter counterpart is usually accompanied. When equal amounts of matter and antimatter particles meet, they annihilate each other.

Scientists believe that when the universe formed in the Big Bang, matter and antimatter should have been created in equal amounts. However, some mechanism prevents matter and antimatter from completely annihilating in their usual fashion, and the universe around us is dominated by matter.

The Standard Model fails to account for this imbalance. Many different experiments are studying matter and antimatter for clues that could change the balance.

The fourth question, why is the expansion of the universe accelerating?

Before scientists were able to measure the expansion of the universe, they guessed that the universe started expanding quickly after the Big Bang and then, over time, started to slow down. Shockingly, however, actual observations show that instead of slowing down, the expansion of the universe is accelerating.

Galaxies across the universe are moving away from us at 45 miles per second, astronomers' latest measurements show. The velocity doubles for every additional millionth of a second, or 3.2 million light-years, relative to our position.

This rate is thought to come from an unexplained property of spacetime - dark energy - that is pushing the universe away. It is thought to make up 68% of the energy in the universe.

Dark energy is also outside the Standard Model.

One last question, are there particles related to gravity?

The Standard Model is not designed to explain gravity. This fourth and weakest force of nature doesn't seem to have any effect on the subatomic interactions explained by the Standard Model.

But theoretical physicists think the graviton, a subatomic particle, might transmit gravity in the same way that photons carry the electromagnetic force.

If Pang Xuelin can propose a new physics framework on the basis of the standard model, not only is it possible to solve these five major problems, but its historical significance in physics will be no less than that of Newton and Einstein, two god-level figures!

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