Hypernuclear Fine Structure inBΛ9e

Abstract

With a germanium detector array (Hyperball), we observed two gamma-ray peaks corresponding to the two transitions (5/2(+)-->1/2(+) and 3/2(+)-->1/2(+)) in the (9)(Lambda)Be hypernucleus which was produced by the 9Be(K-,pi(-)) reaction. The energies of the gamma rays are 3029 +/- 2 +/- 1 keV and 3060 +/- 2 +/- 1 keV. The energy difference was measured to be 31.4(+2.5)(-3.6) keV, which indicates a very small Lambda-spin-dependent spin-orbit force between a Lambda and a nucleon. This is the smallest level splitting by far ever measured in a hypernucleus.

Parity reversal ofΛ12Be

“…1(c), this difference leads to the opposite level ordering of the the 0 doublets between the ND and NSC97f results, while these doublets are almost degenerated in the ESC08c result. It is found that the contribution from the spin-orbit interaction of ESC08c is less than 100 keV for 0 ± 1 and 1 ± 1 doublets, which is consistent with the observations in 9 Be [45,46] and 13 C [47,48]. Therefore, we consider that the uncertainty of the spin-orbit interaction has minor influence to the parity reversion compared to other uncertainties discussed above.…”

Possible Lightest Ξ Hypernucleus with Modern ΞN Interactions

“…Unlike the case of the N N interactions, hyperon interactions are not well determined experimentally due to insufficient number of scattering data. Nevertheless, high-resolution γ-ray experiments [2][3][4][5] analyzed by the shell model [6] as well as the accurate few-body method [7] have provided valuable constraints on the Y N interaction in the Strangeness = −1 sector such as the ΛN force. Also, the ΛΛ interaction in the Strangeness = −2 sector receives some constraints from the binding energies of hypernuclei such as 6 ΛΛ He [8], 10 ΛΛ Be [9] and 13 ΛΛ B [10].…”

“…The HAL QCD potential is obtained from first principles (2+1)-flavor lattice QCD simulations in a large spacetime volume, L 4 = (8.1 fm) 4 , with nearly physical quark masses, (m π , m K )=(146, 525) MeV, at a lattice spacing, a=0.0846 fm. Such simulations together with the HAL QCD method [24,25] enable one to extract the Y N and Y Y interactions with multiple strangeness, e.g.…”

Missing-mass spectroscopy with the Li6(π−,K+)X reaction to search for Honda1, Agnello2, Ahn3 et al. 2017Phys. Rev. CSelf Cite142300View full textAdd to dashboardCite

“…Then, the system is bound more deeply. This gluelike role stabilizes several unstable nuclear systems, like 9 Λ Be [1] and 6 Λ He [2]. Actually, the ground states of 8 Be and 5 He are particle unstable.…”