In 2009, physicists from Japan’s KEK high-energy proton accelerator announced the sighting of a rare event: an unusually bulky beryllium nucleus that, in addition to four protons and five neutrons, contained two particles called ‘hyperons’.
Now, Emiko Hiyama at the RIKEN Nishina Center for Accelerator-Based Science, Wako, and her colleagues from several Japanese universities have presented a calculation that provides the most precise description available of the interactions between nuclei and hyperons in the double-hyperon beryllium nucleus observed at KEK1.
Hyperons—particles that contain at least one so-called ‘strange’ quark—exist for less than a billionth of a second before they decay. Scientists know relatively little about how hyperons interact with matter, but speculate that the hot, dense environment of a neutron star would allow these particles to exist in an almost stable state. If they are correct, a hyperon neutron star would be a new state of matter.
According to Hiyama, one of the main interests of hypernuclear physics is to understand interactions between baryons—particles such as protons and neutrons that consist of three quarks—and other particles. “Our study will contribute to understanding such interactions at the core of a neutron star.”
Quarks come in six so-called ‘flavors’: up, down, strange, charm, bottom and top. Only the up and down quarks, which make up the protons and neutrons in atomic nuclei, are stable. High-energy collisions, such as those performed at KEK, are needed to produce the hyperons that contain the more massive strange quark.
Finding the interactions between the eleven particles that constitute the double-hyperon beryllium nucleus is prohibitively difficult. To simplify the calculation of this ‘many-body’ problem, Hiyama and her colleagues approximated the double-hyperon nucleus as five particles: two helium nuclei, one neutron and the two hyperon particles (Fig. 1). This allowed them to predict the energy that binds the two hyperons together in the nucleus and compare their theoretical results with experimental data. Their calculations indicated that hyperons act to shrink the beryllium nucleus—an unusual effect, since nuclei are normally considered incompressible.
Hiyama’s calculations will be an essential tool to understand the attractive forces between hyperons in a neutron star, and will help researchers to analyze experimental results at Japan’s new proton accelerator complex, J-PARC, which is expected to produce multiple double-hyperon nuclei.
“At present, the only way to determine the energy of the hypernucleon is to perform these accurate many-body calculations,” says Hiyama.
The corresponding author for this highlight is based at the Strangeness Nuclear Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science
1. Hiyama, E., Kamimura, M., Yamamoto, Y. & Motoba, T. Five-body cluster structure of the double-Ë hypernucleus 11ËËBe. Physical Review Letters 104, 212502 (2010)
gro-pr | Research asia research news
Pulses of electrons manipulate nanomagnets and store information
21.07.2017 | American Institute of Physics
Vortex photons from electrons in circular motion
21.07.2017 | National Institutes of Natural Sciences
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
21.07.2017 | Earth Sciences
21.07.2017 | Power and Electrical Engineering
21.07.2017 | Physics and Astronomy