Light “Hypernucleus” Predicted to Be Stable Despite Having Two Strange Quarks

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Bound Nucleus Containing Three Normal Nucleons

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An artist’s impression of a bound nucleus including 3 typical nucleons, which have up and down quarks, and a Xi hyperon (gold sphere at bottom right), which consists of 2 odd quarks. Calculations by RIKEN nuclear physicists forecast that this unique nucleus will be steady. Credit: © 2020 Keiko Murano

Calculations forecast that a light ‘hypernucleus’ including a particle with 2 odd quarks will be steady

Adding an unique particle called a Xi hyperon to a helium nucleus with 3 nucleons might produce a nucleus that is briefly steady, computations by RIKEN nuclear physicists have actually forecasted. This result will assist experimentalists look for the nucleus and supply insights into both nuclear physics and the structure of neutron stars.

Normal atomic nuclei include protons and neutrons, which are jointly called nucleons. Each proton and neutron in turn is comprised of 3 quarks. Quarks are available in 6 types: up, down, odd, beauty, bottom and top. But protons and neutrons consist just of up and down quarks.

Nuclear physicists have actually long had an interest in hypernuclei—nuclei which contain several hyperons in which a minimum of among the 3 quarks is an odd quark. While just a handful of hypernuclei have actually been developed at nuclear physics centers, they supply an important brand-new window into the secrets of nuclei.

“Standard nuclei are defined by how many protons and neutrons they contain, and that’s it. They’re essentially two dimensional,” states Takumi Doi at the RIKEN Nishina Center for Accelerator-Based Science and the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program. “Hyperons offer us an extra dimension through the number of strange quarks—this enables us to gain deeper insight into a nucleus, such as the interactions that make a nucleus stable.”

Most research studies have actually concentrated on hyperons which contain simply one odd quark. But hyperons with 2 odd quarks, called Xi hyperons, are likewise possible. So far, one hypernucleus including a Xi hyperon and 14 nucleons has actually been made.

Doi and colleagues presumed that lighter hypernuclei including Xi hyperon might exist, and they carried out computations of the interaction in between a Xi hyperon and a nucleon on RIKEN’s K supercomputer to learn. Their results forecast that a hypernucleus comprised of 3 typical nucleons and one Xi hyperon ought to be steady adequate to be made in experiments. According to their computations, this is the lightest hypernucleus including a Xi hyperon.

Their results came as a surprise since they varied significantly from those gotten utilizing an approximation. “We predicted that the interaction is attractive when the Xi hyperon and a nucleon are in a particular state, whereas an approximate approach estimates that the corresponding potential will be repulsive,” states Doi. “So these results are very different.”

The outcomes will not just offer experimentalists a target to go for, they will likewise notify research studies into neutron stars. Neutron stars are the very thick residues of big stars that have actually collapsed under their own gravity and gone through supernova surges. Their interiors might supply the conditions under which hypernuclei including Xi hyperons might exist.

Reference: “Possible Lightest Ξ Hypernucleus with Modern ΞN Interactions” by E. Hiyama, K. Sasaki, T. Miyamoto, T. Doi, T. Hatsuda, Y. Yamamoto and Th. A. Rijken, 4 March 2020, Physical Review Letters.
DOI: 10.1103/PhysRevLett.124.092501