• Health Is Wealth
  • Posts
  • Did Freeman Dyson solve the puzzle with a six-quark hadron?

Did Freeman Dyson solve the puzzle with a six-quark hadron?

An exotic hadron, formed of six quarks, had already been considered in 1964 by Freeman Dyson. After its probable discovery a few years ago, two physicists suggest that clusters of these hadrons in the form of Bose-Einstein condensate left by the Big Bang could account for dark matter.

This is probably the buzz of the moment on the black matter and it is based on a paper a priori quite serious since it was published in Journal of Physics G: Nuclear and Particle Physics and that it was therefore examined by a few expert colleagues of the authors of the article, two physicists stationed atUniversity of york in the north of England, Mikhail Bashkanov and Daniel Watts.

As the two researchers explain in the article available in free access on arXiv, they propose a scenario to explain the dark matter based not only on the physical particles known but from a particle that we seem to have indeed highlighted in terrestrial laboratories a few years ago, a hadron exotic containing six quarks.

The idea is therefore probably more attractive for those who do not like to postulate the existence of new particles from new physics, of which we still unfortunately do not see any trace in accelerators or detectors in space such AMS or buried as Xenon1T.

As ABSMARTHEALTH explained in the previous article below, this "hexaquark" was baptized d * (2380) but above all, its discovery confirmed a theoretical prediction made in 1964 by the legendary Freeman Dyson with his colleague Nguyen-Huu Xuong, only a few months after the publication by George Zweig and Murray Gell-Mann of their quark theory. Freeman Dyson has unfortunately passed away and it would therefore have been interesting to know what he thought of the ideas put forward by Mikhail Bashkanov and Daniel Watts.

A ehealth explaining the concept of Bose-Einstein condensation. © Research group " Physics Otherwise »With the support of the PALM labex

Bose-Einstein condensates from an exotic hadron

Remember that baryons are particles made up of three quarks, as the proton and the neutron, while the mesons are composed of a quark and an antiquark. In fact, d * (2380) could be rather a dibaryon, that is to say a kind of bound state of two baryons like two atoms can form a molecule.

Let us also remember that we postulate the existence of dark matter because the stars in the galaxies and the galaxies in them cluster of galaxies have some gears too high which seem to betray, for billions of years, the existence of a distribution of mass more important than that in the form of stars or gas and which we know, for various reasons, that this mass distribution which does not radiate cannot be made up of protons and neutrons, therefore baryons of big Bang. The particles constituting the dark matter must therefore be particularly stable. However, d * (2380) is very unstable, it disintegrates very quickly, which a priori excludes him as a candidate for the title of dark matter particle.

But Mikhail Bashkanov and Daniel Watts seem to have found a way out. Their calculations suggest that when a large number of d * (2380) are present and form a kind of gas, they can come together to give what is called a Bose-Einstein condensate. In fact, a collective quantum state of a particle gas predicted by Albert Einstein in 1925, based on the work of Satyendra Nath Bose, and which was highlighted in 1995 by Eric Cornell and Carl Wieman, discovery earning them the Nobel Prize in physics in 2001.

A Bose-Einstein condensate from d * (2380) would be sufficiently stable according to them to constitute a particle of dark matter. It would remain so up to a size of the order of that of an atom, therefore an Ångström, and could weigh up to a few grams. A wide range of sizes and masses is possible and a sufficient quantity of these drops BE condensate, made up of a large number of hexaquarks (a few thousand to a few million), could have been produced by the Big Bang to account for the amount of dark matter observed, still according to researchers' calculations. They would be vestiges of the phase transition having passed the quagma – the plasma quarks and gluons free – drops of liquid hadronic, i.e. protons and neutrons when theUniverse has cooled sufficiently by the time big Bang.

A presentation of the quagma. The first creation of this plasma of quarks and gluons by Humanity was announced in February 2000 by Cern researchers. The study of this plasma was continued thereafter, especially at the Brookhaven National Laboratory in the United States, in particular with the relativistic heavy ion collider (RHIC, Relativistic Heavy Ion Collider). It is essentially produced by accelerating in opposite directions two bundles of heavy nuclei, copper or gold to make them collide head-on. The same can be done at the LHC with lead cores. Similar experiments concerning the quagma were thus carried out with the Alice detector. To obtain a fairly faithful translation into French, click on the white rectangle at the bottom right. English subtitles should then appear. Then click on the nut to the right of the rectangle, then on "Subtitles" and finally on "Translate automatically". Choose "French". © Fermilab

Except that there is a catch, such condensates should be very, very strongly positively charged therefore radiate copiously from the light when they are accelerated within cosmic rays for example. A condensate of d * (2380) is therefore NOT dark matter … unless it surrounds itself with other negatively charged particles (antiprotons, electrons ?) to form a linked and neutral state like an atom.

A variation on the theme of quark nuggets

This is what Mikhail Bashkanov and Daniel Watts postulate, but it obviously makes their hypothesis more complicated, and therefore less credible. However, forming the analog of an atom with electrons very strongly linked to a very heavy and very positively charged nucleus, it could have lines ofbroadcasts detectable aliens, which would make dark matter not completely dark and would open a window possible observation to Review the scenario of the two physicists.

In fact, we are in the presence of a variant of the theories advanced in the early 1980s to explain the existence of dark matter from clusters of quarks, in particular in Edward Witten's 1984 work, the great superstring theorist and winner of the Fields Medal in mathematics, which led to what are called quark nuggets (quark nuggets, in English) or strangelets. In this case, they were clusters of very many quarks made up of a third of quarks u, another of quarks d and finally a last third of strange quarks s, which again would be stable but positively charged and should therefore surround themselves, for example, with electrons to be neutral. Witten also believed that large quantities of strangelets could have been created at the very beginning of the history of the observable Universe, when it was cooled enough for the quagma to condense into hadrons.

We have looked for these strangelets in accelerator experiments, without success so far. They could be observed in the form of very heavy nuclei with a weak electric charge in the products of collisions. We can think that a similar flush is possible with the condensates of d * (2380), assuming that they exist …

We discovered an exotic hadron with six quarks

Article by Laurent Sacco published on 14/06/2014

A dibaryon may have been identified in Germany, at the Jülich Research Center, as part of the Wasa-at-Cozy collaboration. In any case, it is indeed a hadron exotic, formed of six quarks, already considered in 1964 by Freeman Dyson. With the discovery of what could be a tetraquark, this dibaryon suggests that the world of hadrons is even more diverse than previously thought.

Freeman Dyson celebrated his 90th birthday in December 2013 at Princeton. The contributions to the science of this mathematician and theoretical physicist concern several fields of physics. We owe him many original ideas, such as that of trying to highlight directly gravitational waves using the Earth as a detector, or to look for evidence of the existence of life on Europe, the Moon of Jupiter, by examining fragments of ice floe ejected into space by impacts of meteorites.

In 1964, only a few months after the publication by George Zweig and Murray Gell-Mann of their theory of quarks, Dyson discovered with his colleague Xuong that it implied the existence of sorts of linked states of two baryons. Recall that baryons are particles composed of three quarks, like the proton and the neutron, while the mesons are composed of a quark and an antiquark. It will take another decade for the ideas of Gell-Mann and Zweig to take hold. For this, of course, a series of experimental discoveries will be necessary, but not only. The beginning of the 1970s was also marked by the rise of gauge theories, the discovery of equations field describing the strong nuclear force between quarks and work on the group renormalization of the Nobel Prize in Physics Kenneth Wilson.

Resonance which betrays an exotic hadron

However, despite all this progress and the highlighting of six different types of quarks (while Gell-Mann and Zweig only postulated three), nothing had come to confirm the prediction of Dyson and Xuong. However, it has not been forgotten, as an article published on arxiv by members of the Wasa-at-Cozy collaboration. Their experiment used the Wide Angle Shower Apparatus (Wasa) to study the products of collisions of deuterium nuclei accelerated by the Synchrotron Cooler (Cozy) with protons in a fixed target.

The researchers have highlighted what they call a resonance in the production of pawns, called d * (2380). All door to believe that it is indeed the manifestation of the fleeting existence of a dibaryon, that is to say a kind of linked state of two baryons, as a reaction intermediate in the production of π mesons. This kind of dibaryon is sometimes designated by the term "hexaquark", which leaves open the possibility that it is actually a single hadron composed of six quarks.

This particle is therefore, in any case, an "exotic hadron". This discovery is added to that of exotic mesons, which we know that some contain four quarks, but which it remains difficult to say, there too, if they are authentic tetraquarks or molecules of mesons. What is certain is that the spectrum particles contained in the equations of the quantum chromodynamics is wider than many initially thought. Perhaps it will also involve new physics, such as supersymmetry, to fully account for it.

This will also interest you

Dark energy and dark matter: discovering the dark side of the universe Where is the research on dark matter and dark energy? This previously invisible component of the universe may well be exposed this year, as you will discover in this ehealth.

Did you like this article ? Don't hesitate to share it with your friends and help us to promote ABSMARTHEALTH :)! The editorial team thanks you.