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
Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT
Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine