Calculations forecast that a light ‘hypernucleus’ made up of a particle with two odd quarks will be stable

Incorporating an exotic particle known as a Xi hyperon to a helium nucleus with three nucleons could produce a nucleus that is quickly secure, calculations by RIKEN nuclear physicists have predicted. This final result will assist experimentalists lookup for the nucleus and provide insights into both equally nuclear physics and the composition of neutron stars.

Standard atomic nuclei consist of protons and neutrons, which are collectively regarded as nucleons. Every proton and neutron in convert is created up of a few quarks. Quarks come in 6 varieties: up, down, weird, charm, base and leading. But protons and neutrons consist only of up and down quarks.

Nuclear physicists have very long been fascinated in hypernuclei—nuclei that include a single or additional hyperons in which at the very least 1 of the a few quarks is a peculiar quark. Though only a handful of hypernuclei have been created at nuclear physics services, they provide a worthwhile new window into the mysteries of nuclei.

“Standard nuclei are defined by how a lot of protons and neutrons they consist of, and which is it. They’re essentially two dimensional,” states Takumi Doi at the RIKEN Nishina Center for Accelerator-Centered Science and the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program. “Hyperons supply us an excess dimension through the amount of weird quarks—this permits us to attain further insight into a nucleus, this sort of as the interactions that make a nucleus secure.”

Most scientific studies have focused on hyperons that have just a single weird quark. But hyperons with two peculiar quarks, known as Xi hyperons, are also attainable. So significantly, just one hypernucleus made up of a Xi hyperon and 14 nucleons has been created.

Doi and co-personnel suspected that lighter hypernuclei containing Xi hyperon may well exist, and they done calculations of the conversation in between a Xi hyperon and a nucleon on RIKEN’s K supercomputer to come across out. Their results predict that a hypernucleus produced up of a few standard nucleons and 1 Xi hyperon need to be steady enough to be created in experiments. According to their calculations, this is the lightest hypernucleus that contains a Xi hyperon.

Their benefits came as a surprise since they differed considerably from those attained making use of an approximation. “We predicted that the interaction is beautiful when the Xi hyperon and a nucleon are in a distinct condition, while an approximate solution estimates that the corresponding opportunity will be repulsive,” states Doi. “So these success are extremely various.”

The results will not only give experimentalists a goal to intention for, they will also advise scientific tests into neutron stars. Neutron stars are the exceptionally dense remnants of substantial stars that have collapsed under their own gravity and been through supernova explosions. Their interiors may possibly present the circumstances underneath which hypernuclei made up of Xi hyperons could exist.

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