From graviton to magnetic monopole: the hypothetical subatomic particles that some physical theories predict and we haven’t found yet
At the time, the Higgs boson was a hypothetical particle. So was the photon or the W and Z bosons. They all fit the standard model of particle physics. A theory that over the years and the successive improvements in the accelerators has been consolidated. Even so, there are still a large number of subatomic particles where Although theories predict their existence, they have not yet been empirically detected.
In this group of hypothetical subatomic particles we find some where there is considerable evidence and consensus, such as the case of the graviton, even others, like the tachyons, where they only have a place in theoretical models with less support.
Theorized since the 1930s, the graviton is the hypothetical particle that would be the in charge of transmitting the gravitational interaction. In an equivalent way to how the photon is light or the electron is the negative charge, the graviton would be the particle that constitutes the transmission of gravity.
Quantum field theory is considered quite successful in describing the universe and it predicts the existence of this boson that would operate in a similar way to the photon. Its mass It would below 1.6 x 10-66 g, although it is not ruled out that it is totally zero. By carrying so little energy, its detection is extremely difficult.
One of the possibilities that it is proposed is look for them around extreme gravitational events like black hole mergers.
Physicist Arnold Sommerfeld was the first to speak of them in the early 20th century, but it wasn’t until 1967 that Gerald Feinberg named them. It is one of the most popular hypothetical subatomic particles in science fiction, as its existence could imply that the principle of causality is broken and the travels in the time they would be a possibility.
We refer to a tachyon as that particle that would be able to move faster than light. A superluminal particle that could not be observed and that, according to Einstein’s Theory of Relativity, would have an imaginary mass and proper time.
In quantum field theory and in some versions of string theory its existence is established, since mathematically there are elements to locate the fit of these particles. In 2011, a CERN experiment caused quite a stir to detect that a tau neutrino had traveled at a speed greater than light. However, subsequent reviews indicated that it was a misreading.
Slepton and squark
The supersymmetry, also known in English by the acronym SUSY, is an extension of the Standard Model of Particles. At the moment the existence of this supersymmetry has not been experimentally proven, but it is a widely used theory to explain some properties of bosons and fermions.
One of the consequences of this supersymmetry is the existence of “super companions”. From here the sleptons would arise, those corresponding to leptons but with spin 1, and squarks, the superpartner particles of the different quarks, with spin 0. Among these groups of particles we find a whole series of new hypothetical particles.
During the 1980s it was a very popular theory, but the lack of evidence during the commissioning of the Large Hadron Collider at CERN it has raised many doubts.
Chargino, fotino, wino, zino, gravitino, gluino…
If supersymmetry is confirmed, we would find ourselves before a large number of new subatomic particles. The “super companion” is usually referred to with a name ending in “-ino”Hence, we have the chargino for the electrically charged fermions, the Higgsino for the one corresponding to the Higgs boson, the wino for the W boson or the photino for the photon.
Also located in this category of hypothetical particles is the neutralino, considered a good candidate for a “weakly interacting massive particle” (WIMP). A type of particle that could explain the origin of dark matter.
Until a few weeks ago, the odderon was a hypothetical particle, although the LHC of the CERN has confirmed its existence, 50 years after its prediction. It is a rare combination of three fundamental particles.
Simone Giani, CERN portavoz, Explain that the find “test the deepest ideas of the quantum theory of chromodynamics, especially the one that defines that gluons interact with each other and that an odd number of them can be ‘colorless’ and thus hide their interactions “.
Another of the candidates to explain dark matter is the axion. Its existence was postulated in 1977 by the Peccei-Quinn theory and we would be before a particle of very small mass and without electrical charge. According to theorists, some photons could temporarily become axions. This would help explain why high-energy photons can avoid being absorbed by background radiation.
During the early stages of the universe, a large number of these axions would have been produced, but for the moment we are far from verifying their existence. The ADMX experiment is located at the University of Washington that could detect if dark matter is made up of these hypothetical particles.
At FermilabAlong with the search for axions, they are also trying to find signs of chameleons with the GammeV experiment. We are facing a particle predicted in 2003 by Khoury and Weltman and where its mass would come as a function of energy density.
His existence would help explain the acceleration of the expansion of the universe, in this case being one of the particles candidates to explain dark energy. To test the Chameleon theory an attempt was made to detect them in 2010, in a failed way. Today simulations continue to be made to find out how they might fit together.
As described by the Kaluza-Klein theory, a generalization of general relativity, the graviphoton would be a particle analogous to the photon but the result of the gravitational field. We would be before a “super partner” of the graviton. Unlike the latter, it could also provide a repulsive force and therefore a kind of antigravedad.
In 1979, J.Scherk, tried to investigate and model its existence, but at the moment the graviphoton is usually included as one of the most hypothetical particles and without a firm base on which to continue its search.
Bosons X and Y
The X and Y bosons are predicted by the Georgi-Glashow model, a grand unification theory attempt. They are analogous to the W and Z bosons and would open the possibility of new phenomena such as proton decay. These hypothetical bosons would couple to quarks and leptons and allow the violation of baryon number conservation. Following this theory, it would help to answer why there is an excess of matter with respect to antimatter.
Paul Dirac, father of quantum electrodynamics, did not accept the apparent asymmetry of Maxwell’s equations. Due to this vision, he formulated the existence of the magnetic monopole, a hypothetical elementary particle that would only contain a magnetic pole and therefore would be the equivalent of the magnetic charge.
In the 1970s, Gerard ‘t Hooft and Aleksandr Polyakov described monopoles as a result of grand unification theories. If they exist, they would be extremely massive particles.
Although their existence is not proven, in recent years they have achieved different experiments that have analyzed magnetic monopoles. Both in the Large Hadron Collider with the experimento MoEDAL (‘Monopole and Exotics Detector at the LHC’), in crystals, at ATLAS, in condensed matter or with the ANTARES telescope.