- Researchers predicted a new type of dibaryon – particle with 6 quarks instead of usual 3.
- To do this, they created quantum chromodynamics simulations on K computer.
- It is made up of 2 Omega baryons, called di-Omega, containing 3 quarks each.
Baryons are heavy subatomic particles that contain 3 quarks. The most common baryons are neutron and protons, present in all visible matter in the universe. These quarks-based particle engage in the strong interaction, and each of them has a corresponding antibaryon.
A system consisting 2 baryons is called dibaryon. At present, we know only one dibaryon, called deuterium, that accounts for nearly 0.015% of all naturally occurring hydrogen in the oceans. The nucleus of deuterium, known as a deuteron, consists of one proton and one neutron.
For decades, researchers have wondered whether there could be other classes of dibaryons. Despite numerous searches and studies, no other dibaryon has been discovered till date.
Now, a team of scientists at Riken (a large research institute in Japan) has predicted a new type of dibaryon. Studying formation and behavior of these elements could help us better understand how elementary particles interacts with each other in extreme conditions, like in the early stages of the universe and the interiors of neutron stars.
How Did They Do This?
To predict this unusual element, scientists created quantum chromodynamics simulations on K computer, which is based on a distributed memory architecture with over 80,000 computer nodes.
The proposed dibaryon is made up of 2 Omega baryons — called di-Omega — containing 3 quarks each. The research team suggested a method to observe these unusual elements through heavy ion collision experiments planned in Japan and Europe.
Image credit: Forschungszentrum Jülich / SeitenPlan
The combination of three efficient components made this research possible-
- Powerful supercomputer,
- Better simulation algorithms, and
- Better approach of making quantum chromodynamics calculations.
Although K computer — one of the fastest supercomputers with a computation speed of over 8 petaflops — enabled fast calculations of large number of variables, it took them nearly 3 years to reach to this conclusion.
The unified contraction algorithm made the calculations even more efficient with huge number of quarks. Furthermore, a new theoretical framework (time-dependent) named HAL quantum chromodynamics (QCD) allows scientists to measure the force of interaction among baryons.
The scattering length, binding energy and effective range obtained by the HAC QCD technique show that the dibaryon system has an overall attraction and is located in the vicinity of the unitary regime.
From the phenomenological point of view, these types of systems can be best searched by measuring pair-momentum correlation, i.e. the relative momentum between 2 baryons formed in relativistic heavy-ion collisions. Moreover, scattering length is the crucial element for pair-momentum correlation to have characteristic enhancement at small relative momentum.
Researchers are currently working the increase the QCD data with the same setup. They will soon publish the results together with the in-depth examination of the spectrum analysis in a finite QCD volume and the effective range expansion.