Observation of a K ¯N N bound state in the 3He(K-,Λ p )n reaction
Abstract
We have performed an exclusive measurement of the K-+3He→Λ p n reaction at an incident kaon momentum of 1 GeV /c . In the Λ p invariant mass spectrum, a clear peak was observed below the mass threshold of K ¯+N +N , as a signal of the kaonic nuclear bound state, K ¯N N . The binding energy, decay width, and S -wave Gaussian reaction form factor of this state were observed to be BK=42 ±3 (stat.) -4 +3(syst . ) MeV , ΓK=100 ±7 (stat.) -9 +19(syst . ) MeV , and QK=383 ±11 (stat.) -1 +4(syst . ) MeV /c , respectively. The total production cross section of K ¯N N , determined by its Λ p decay mode, was σKtotB RΛ p=9.3 ±0.8 (stat.) -1.0 +1.4(syst . ) μ b . We estimated the branching ratio of the K ¯N N state to the Λ p and Σ0p decay modes as B RΛ p/B RΣ0p∼1.7 , by assuming that the physical processes leading to the Σ N N final states are analogous to those of Λ p n .
- Publication:
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Physical Review C
- Pub Date:
- October 2020
- DOI:
- 10.1103/PhysRevC.102.044002
- arXiv:
- arXiv:2006.13433
- Bibcode:
- 2020PhRvC.102d4002Y
- Keywords:
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- Nuclear Experiment
- E-Print:
- 13 pages, 12 figures