The 6 types of bosons (and their characteristics)

Everything that happens in the Universe has its origin in the subatomic world. If we want to understand the elemental nature of everything, we must immerse ourselves in the mysteries of quantum mechanics. And when it comes to the fundamental understanding of the four forces of the Cosmos, there can be no exception. Everything must be able to be explained from the subatomic perspective.

Gravity, electromagnetism, the weak nuclear force and the strong nuclear force. These are the four fundamental forces of the Universe. They are the pillar of the Cosmos. Everything that happens in it responds to the application of some of these forces on the matter that surrounds us. They are the forces that control everything.

And in this context, one of the greatest achievements in the history of physics came when, in the second half of the 20th century, the development of the standard model of particles was completed. A theoretical framework where not only the particles that gave shape to matter were described, but also those that, through the interactions they carried out in the quantum world, allowed to explain the origin of the four elemental forces.

We are talking about bosons. One of the groups into which the standard model is divided (the other is that of fermions) and where includes particles exerting fundamental forces. They do not compose matter but they do make it possible for interactions to exist. And in today's article we will dive into its mysteries.

What are bosons?

Bosons are the elementary subatomic particles that exert the fundamental forces. They are, in other words, the carriers of the four fundamental interactions: gravity, electromagnetism, the weak nuclear force and the strong nuclear force. They do not compose matter but they do allow the forces that govern the behavior of the Universe to emerge from the quantum world.

As subatomic particles, bosons are indivisible units found within the standard model of particle physics. A theoretical framework where the particles are divided into fermions or bosons depending on whether they make up the mass or whether they make possible the existence of elementary interactions, respectively.

The subatomic particles that we are most familiar with, such as quarks (which give rise to protons and neutrons) and electrons are fermions, not bosons. But it is in these bosonic particles that the quantum nature of both the fundamental forces and the mass of the other subatomic particles is hidden.

Unlike fermions, bosons do not comply with the Pauli exclusion principleTherefore, within the same quantum system, two bosons can have all their quantum numbers identical. That is, two bosons can have the same quantum state, something that does not happen with the fermionic particles that constitute, for example, the atoms of matter.

Be that as it may, bosons are the pillar of universal forces, being responsible for the interactions that culminate in the existence of gravity (although we will have to make a point later), of electromagnetism, of the weak nuclear force, of the strong nuclear force and the mass of matter.

How are bosons classified?

As we have seen, bosons are subatomic particles that do not constitute the elementary building blocks of matter but that do explain the quantum existence of the fundamental forces of the universe. Before we start, it should be made clear that there are two main groups of bosons: Gauge bosons (responsible for the four forces) and scalars (for now, only the Higgs boson is included). With that said, let's get started.

1. Photons

Photons are a type of massless bosons with no electrical charge. They are the subatomic particles within the group of Gauge bosons responsible for the existence of the electromagnetic force. Photons make it possible for magnetic fields to exist.

We can also understand photons as "the particles of light", so, in addition to making electromagnetism possible, they allow the existence of the wave spectrum where visible light, microwaves, infrared, gamma rays, and ultraviolet are found. , etc.

The electromagnetic force, which is carried by these photons, is the elemental force of interaction that occurs between electrically charged particles positively or negatively. All electrically charged particles experience this force, which is manifested by an attraction (if they are of different charge) or a repulsion (if they are of the same charge).

Magnetism and electricity are linked through this photon-mediated force, which is responsible for countless events. Since the electrons orbit around the atom (the protons have a positive charge and the electrons, negative charge) to the lightning of the storm. Photons make it possible for electromagnetism to exist.

2. Gluons

Gluons are a type of boson without mass and without electrical charge, but with a color charge (a type of gauge symmetry), so it not only transmits a force, but also experiences it itself.

Either way, the important thing is that gluons are responsible for the strong nuclear force. Gluons make possible the existence of what is the strongest force of all. Forgive the redundancy. And it is a force that allows matter to exist.

Gluons are the carrier particles for the interaction that constitutes the "glue" of atoms. The strong nuclear force allows protons and neutrons to stick together (through the strongest interaction in the Universe), thus maintaining the integrity of the atomic nucleus.

These gluonic particles transmit a force 100 times stronger than that transmitted by photons (electromagnetic) and that is of a shorter range, but enough to prevent the protons, which have a positive charge, repel each other. Gluons ensure that, despite electromagnetic repulsions, protons and neutrons remain attached to the nucleus of the atom.

3. Z bosons

Z bosons are a type of very massive bosons that, together with W, are responsible for mediating the weak nuclear force. Unlike Ws, Z bosons are electrically neutral and somewhat more massive than they. Even so, and despite the fact that we differentiate them here, as they contribute to the same strength, they are often discussed jointly.

The weak nuclear force is one that acts at the level of the atomic nucleus but receives this name because it is less intense than the strong one that we have seen before. The Z and W bosons are the particles that make possible the existence of this force that allows protons, neutrons and electrons to disintegrate into other subatomic particles.

These Z and W bosons stimulate an interaction that makes neutrinos (a type of fermion of the lepton family), when approaching a neutron (a subatomic particle composed of three quarks, fermions other than leptons), become a proton.

More technically, the Z and W bosons are the carriers of the force that allows the beta decay of neutrons. These bosons move from the neutrino to the neutron. There is the weak nuclear interaction, since the neutron (of the nucleus) attracts (less intensely than in the nuclear one) the Z or W boson of the neutrino. And the neutrino, losing a boson, becomes an electron. And the neutron, by gaining a boson, becomes an electron. This is the basis of the weak nuclear force.

4. W bosons

W bosons are a type of very massive bosons that, like Z bosons, are responsible for the weak nuclear force. They have a slightly lower mass than Z bosons and, unlike Z bosons, they are not electrically neutral. We have positively charged (W +) and negatively charged (W-) bosons W. But, at the end of the day, their role is the same as that of the Z bosons, since they carry the same interaction that we have just detailed.

5. Higgs boson

We end up with the gauge bosons and we are going to talk about the only scalar boson (with a spin of 0) discovered to date: the famous Higgs boson. The discovery of the Higgs boson in 2012 was so important because the detection of this boson particle was proof that the Higgs field existed.

That is, the important thing was not the particle itself (the boson), but to confirm the existence of the associated field. The Higgs field is a quantum field, a kind of cloth that permeates the entire Universe and that it extends throughout all space, giving rise to a medium that interacts with the fields of the rest of the standard model particles, providing them with mass.

The discovery of the Higgs boson allowed us to understand the fundamental origin of mass. That is, understand where the mass of matter comes from. And it is that the mass would be the result of particles being slowed down within this ocean that constitutes the Higgs field.

Mass, then, is not an intrinsic property of matter. It is an extrinsic property that depends on the degree to which a particle is affected by the Higgs field. Those that have the most affinity for this field will be the most massive (like quarks); while those with the least affinity will be the least massive. If a photon has no mass, it is because it does not interact with this Higgs field.

The Higgs boson is a particle without spin or electric charge, with a half-life of one zeptosecond (one billionth of a second) and that could be detected by excitation of the Higgs field, something that was achieved thanks to the Large Hadron Collider , where it took three years of experiments colliding 40 million particles per second at close to the speed of light to disturb the Higgs field and measure the presence of what was later called "The particle of God". The Higgs boson is the unstable particle that allows us to understand the origin of the mass of matter.

6. Graviton?

So far, we have understood the quantum origin, through its mediating particles, of the mass of matter and of three of the four fundamental forces. Only one is missing. The gravity. And here comes one of the biggest problems facing physics today. We have not found the boson responsible for the gravitational interaction.

We do not know which particle is the carrier of such a weak force but of such enormous scope, allowing the attraction between galaxies separated by millions of light years. Gravity does not fit, for now, within the standard model of particles. But there has to be something that conveys gravity. A boson that mediates gravity.

Thus, physicists go in search of what has already been dubbed the graviton, a hypothetical subatomic particle that makes it possible to explain the quantum origin of gravity and to finally unify the four fundamental forces within the theoretical framework of quantum mechanics. But for now, if this graviton exists, we are not able to find it.