Physicists from the US and Germany have found a way to describe the behavior of quarks and gluons in nuclear matter using quantum chromodynamics (QCD) – the theory of strong interaction. Their results published in the journal Physical Review Letters.

Quarks are the elementary particles that make up hadrons – protons, neutrons and other particles. Gluons are bosons that carry the strong force between quarks. Each quark has a color charge – one of three colors (red, green or blue) or their anticolor. Gluons also have a color charge, but as a combination of color and anticolor.

Usually the matter in hadrons is in the so-called colorless (“white”) state. That is, quarks of different colors compensate each other. However, at very high temperatures or densities, quarks and gluons can form a new state of matter – a quark-gluon plasma, in which they move freely and are not bound into hadrons.

One of the problems physicists face is how to accurately describe the properties of a quark-gluon plasma using QCD. The point is that the QCD equations are very complex and cannot be solved analytically. Therefore, scientists resort to numerical methods, such as lattice QCD, which represents space-time as a discrete grid of points.

However, this method has its limitations. In particular, it cannot be used to describe nuclear matter at high densities, such as in neutron stars. In addition, it requires large computational resources and time.

Scientists from the University of Washington, the University of Bonn and the Max Planck Institute for High Energy Physics have proposed a new approach to solve this problem. They used the functional renormalization group (FRG) method, which makes it possible to take into account the effects of quantum fluctuations at different scales.

With the help of the Federal Republic of Germany, scientists were able to obtain the equation of state of the quark-gluon plasma, which is in good agreement with experimental data and numerical calculations. They also found that the quark-gluon plasma has a property called critical opalescence – a sharp change in the transparency of matter when passing through the critical point of the phase transition.

This result is an important step in the understanding of quarks and gluons in nuclear matter and can help in the study of extreme states of matter, such as inside neutron stars or in the early universe.