Search for the Lightest Double-Λ Hypernucleus, ΛΛ5H, at J-PARC

• Published in: Few-body systems 2021-09, Vol.62 (3)
• Main Authors: Fujioka, Hiroyuki, Ajimura, Shuhei, Fukuda, Tomokazu, Gogami, Toshiyuki, Hiyama, Emiko, Morino, Yuhei, Motoba, Toshio, Nagae, Tomofumi, Nagao, Sho, Sakaue, Akane, Takahashi, Toshiyuki, Taki, Yosuke, Tokiyasu, Atsushi O., Uchida, Makoto, Yosoi, Masaru
• Format: Article
• Language: English
• Subjects: Advances on the Few-Body Problem in Physics – Selected and Refereed papers from the 8th Asia-Pacific Conference; Atomic; Baryons; Coupling; Decay; Experiments; Hadrons; Heavy Ions; Hypernuclei; Hyperons; Molecular; Nuclear Physics; Optical and Plasma Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Pions; Spectrum analysis; Strangeness
• ISSN: 0177-7963; 1432-5411
• DOI: 10.1007/s00601-021-01635-y

Investigations of double- Λ hypernuclei, which contain two Λ hyperons in a nucleus, provide valuable information on baryon–baryon interaction in the strangeness - 2 sector, such as the Λ – Λ interaction. Whereas several double- Λ hypernuclei have been discovered in nuclear-emulsion experiments, an experimental observation of Λ Λ 5 H is awaited. It is not only because Λ Λ 5 H is theoretically expected to be the lightest bound state, but also because Λ Λ – Ξ N coupling may play an important role in its structure. On the other hand, the coupling effect may be suppressed in Λ Λ 6 He .We propose an experiment to investigate Λ Λ 5 H at J-PARC. Λ Λ 5 H will be produced by a decay of a Ξ hypernucleus, Ξ 7 H, which can be produced by the 7 Li ( K - , K + ) reaction. The mass of Λ Λ 5 H will be determined by means of decay pion spectroscopy; it can be calculated from the measured momentum of decay pions, owing to a two-body decay of Λ Λ 5 H.