Voyage of the Stars

Chapter 523 The Road to a Grand Unified Theory (Please subscribe⊙⊙!)

So what role does the Higgs mechanism play in the process of separation of weak interactions?

As we all know, the so-called Higgs mechanism is actually an important theory in the Standard Model. It explains why some elementary particles have mass and some particles have no mass. It is the mechanism that gives particles mass.

The mechanism involves a ubiquitous field in the universe called the Higgs field, which gives particles mass through spontaneous symmetry breaking.

It can be deduced from gauge field theory, including Yang-Mills theory. If we want to unify the electroweak force under the framework of gauge field theory, we must assume that W and Z bosons do not have mass at first. Their mass is endowed by acquired factors. .

It is also known as the Higgs mechanism.

The process from no mass to having mass is the symmetry breaking process.

After the three propagators of the weak force, the positive and negative W bosons and Z bosons, have mass, their range of action cannot even break through the atomic nucleus, making the weak interaction completely a short-range force.

Its range of action is only 10 minus 18 meters, which is one thousandth of the length of a proton. The electromagnetic force is a long-range force, and its propagator photon has zero mass.

In other words, as long as the mass of the propagator of the weak force is also zero, its expression will become a long-range force like the electromagnetic force. This is the moment of unification of the electroweak force.

So under what circumstances can the propagator mass of the weak force be made zero? The answer is obvious, that is when the symmetry of the gauge field theory is not broken. If the symmetry of the Higgs field is not broken, the Higgs mechanism will not take effect, and the weak force propagator will not gain mass.

The key factor in symmetry breaking depends on temperature.

As long as the temperature is high enough, the Higgs mechanism will fail, symmetry breaking will not occur, W and Z bosons will not be able to gain mass, and the electromagnetic force and the weak interaction force will behave exactly the same. At this time, the propagator speed of the weak interaction force will also become the speed of light, and like the electromagnetic force, it will propagate infinitely in the universe.

The standard particle model predicts that the critical temperature at which the Higgs mechanism fails, that is, the energy level at the critical temperature at which the electromagnetic force and the weak interaction force are unified into one force, is 100 GeV.

Human particle collider has the ability to collide with this energy level, so it really simulates the unification of electromagnetic force and weak interaction force, so it successfully unifies these two forces.

Now, what Liu Miyan means is to continue to use the idea of ​​​​the Standard Model to unify the strong interaction forces. The three forces and one become one force, allowing humans to turn the grand unified theory into reality and become as popular as the electroweak theory. Theories that humans have mastered.

So how to unify the strong interaction?

First of all, we need to understand what kind of force the strong interaction is, the strong force, which is the force responsible for binding together protons and neutrons in the nucleus. In any atomic nucleus, all protons are positively charged. If they are not bound by a strong force, they will be repelled by the electromagnetic force and break the nucleus.

In other words, it is the strong force that overcomes the repulsive force between protons and binds them to the nucleus.

This phenomenon explains why there are only about 100 known elements in nature. That is because after the number of protons in the nucleus exceeds 100, the repulsive force between them cannot be contained even by the strong force.

The propagator of the strong force is a gluon, which is different from the propagator of the weak force. Its mass is zero, so its speed is the speed of light, which is the same as the propagator of the electromagnetic force. The difference is that the strong propagator gluons are trapped between quarks and cannot escape.

This is the so-called quark confinement. The farther the distance between quarks, the stronger the strong interaction. The closer the distance, the weaker. Therefore, the closer the distance between quarks, the freer they are. This phenomenon is called asymptotic freedom. .

So it can be seen from here that if you want to unify the strong interaction force, you must let its propagator break through the quark level and become a long-range force like the electromagnetic force.

According to this idea, we must find a way to make powerful propagators break through quarks. So how can we make powerful propagators break through the quark level?

The answer is still temperature.

The standard model infers that when the environmental energy is above 10 to the 15th power GeV, quarks will no longer be bound by gluons, quark confinement and asymptotic freedom will disappear, and gluons can rush out of atoms at the speed of light. , in this way, strong force becomes long-range force.

In this case, scientists can collect various data, and then follow the improvement methods of scientific theories to complete a powerful unification, allowing humans to master a grand unified theory.

Of course, in this case, the atoms would not exist.

So why do you know that the energy value of 10 to the 15th power GeV is the critical point?

This goes back to what I said before, that the universe is not divided into up and down, front and back, but left and right, and of course quantum chromodynamics.

When human beings, in line with the concept of using force to create miracles, used violence to forcefully smash protons, neutrons, and even blast away quarks, they discovered that after the quark pair was knocked apart, the energy that caused the quark to be knocked apart was exactly the energy needed to form new quarks. .

So, as soon as the quarks were knocked away, the energy instantly formed a new pair of quarks and anti-quarks, and the color charge of the combination of these two new quarks happened to be white. Well, this is because quantum chromodynamics stipulates that the quarks The total color charge can only be white, that is, the color charge.

As a result, gluons transmit the strong force in new pairs of quarks and antiquarks.

It's like hitting loneliness.

Of course, it is not completely lonely. At least this phenomenon also made scientists notice that quarks and antiquarks do not annihilate it.

In people's understanding, matter and antimatter will definitely annihilate together, and this is also true. However, if pairs of quarks and antiquarks stick together, they will not annihilate.

This is magic.

For such a phenomenon, humans must try to figure out why. In fact, with the efforts of countless scientists, we have also figured out the reason.

That's chiral symmetry.

Scientists have discovered that as long as positive quarks and antiquarks have chiral symmetry, that is, chiral symmetry is established, they will annihilate.

On the other hand, if the chiral symmetry is broken, then they don't annihilate, and then from quantum chromodynamics we know that because of the charge in the gluon color, the front and back quarks will come together, and this pulls them together The energy together is the binding energy between quarks.

The universe is not divided into up and down, front and back, but left and right. It is so magical.

This process is called spontaneous chiral symmetry breaking. The binding energy generated by this phenomenon constitutes 99% of the mass of protons and neutrons. Yes, the binding energy at the quark level is expressed as protons and neutrons. the quality of.

This is where the quality of everything we see every day comes from.

It is now obvious that Liu Miyan's purpose is to obtain a more powerful collider so that humans can collide with the 10 to the 15th power GeV energy level in the laboratory and reproduce the chiral symmetry of the Big Bang. The environment has not yet been broken, and then we study what it looks like when it is a strong force or a long-range force, what it looks like when the three forces are combined into one, what are the specific physical manifestations, etc.

Use this to explore and master the grand unified theory.

Science is a subject based on experiments. Without experiments and data, there will be no progress. The threshold of the laws of the universe is not so low that I can grasp it just by thinking about it.

Yu Nanfeng knew all this, so he understood Liu Miyan's appeal. For the same reason, he didn't know what to say at the moment. He also wants to say that humans can build such a collider, and is also willing to see humans have stronger colliders, but the actual technical strength does not allow it!