Hypernuclear Binding Energies and theΛ-Nucleon Interaction

Abstract

A phenomenological analysis is made of the binding-energy data for light hypernuclei in terms of a two-body A-nucleon interaction, in which account is taken of the empirical information available on the structure of light nuclei. It is found that the observed binding energies can be interpreted in terms of a spindependent A-nucleon interaction; the agreement obtained is adequate for any force-range between 0.4X 10~1 3 cm and 0.7X 10~1 3 cm (for Yukawa shape) and any exchange character for this interaction. From observations on AH 4 decay it is argued that the AH 4 , AHe 4 doublet has zero spin, which requires that the singlet A-nucleon interaction be more attractive than the triplet. The well-depth parameter for the singlet A-nucleon interaction has values from 0.90 to 0.85 for ranges between 0.4X10* -13 cm and 0.7X10 -13 cm, the triplet interaction being also attractive but only one-half to one-third as strong. Spin values are assigned to the light hypernuclei, and the angular correlations which could provide a check on these values are discussed. The absorption of K~ mesons in helium is discussed; it appears that the selection rules for the production of A = 4 hypernuclei in this reaction may be confused by the existence of an excited state AH 4 *, AHe 4 *. A number of uncertainties in the phenomenological analysis of the heavier hypernuclei are pointed out; the present data do not disagree with the conclusions based on the analysis of the lighter and better-known hypernuclei with A ^ 5, but they add little weight to these conclusions. et al. arises mainly from the use of a larger Q value for the free A decay: Q A =37.22±0.22 Mev. This value is the average (weighted by the number of events) of two determinations: QA=36.75±0.2 Mev [given by W. Slater, University of Chicago dissertation, 1958 (unpublished)] for 9 of the events reported by Friedlander, Keefe, Menon, and Merlin [Phil. Mag. 45, 533 (1954)] analyzed on the basis of the range-energy relation used in the world survey; and (>A=37.45±0.17 Mev given for 18 events by Barkas, Giles, Heckman, Inman, Mason, and Smith [University of California Radiation Laboratory Report UCRL-3892, 1957 (unpublished)]. Additional shifts in B A for A Li 7 and ALi 8 are due to the incorporation of new events. Further changes in QA (by AQA) will give rise to a change AQA in each of the BA values. 3 R. H.work more realistic assumptions are made about the range of the A-nucleon interaction, and the analysis is extended to include recent data on the heavier hypernuclei. The qualitative conclusions of the present work remain the same as those reported earlier, 3 however, and disagree with the conclusions reached by Brown and Peshkin 4 on the basis of the same assumptions as those of our earlier report. The A particle is now known to be an isotopic-spin singlet (T=0) state. Charge symmetry for strong interactions then requires that the A-neutron and A-proton interactions be identical. That strong support for this situation can be derived from the approximate equality of the BK values ...

Λ-Σ conversion in Λ4He and Λ4H based on a four-body calculation

“…Correspondingly, by including the ΛN-ΣN coupling explicitly, Miyagawa et al [6] performed the Faddeev calculations for 3 Λ H extensively to test these OBE potential models in this lightest system. They found that the ΛN-ΣN coupling is crucial to get the bound state of 3 He( 3 H)+Λ/Σ which was adopted originally by Dalitz and Downs [7], and then carried out the four-body coupled-channel calculation with the separable potentials of central nature [2]. J. Carlson tried to perform four-body calclation of these hypernuclei with NSC89 model by using Variational Monte Carlo method [3] and calculated the binding energies with statistical errors of 100 keV.…”

Neutrino or Electron Energy Needed for Testing Current Commutation Relations

“…(la) and (lc) can be tested in high-energy neutrino reactions, where they imply that, in the limit of infinite incident neutrino energy, the difference do-T (v+N)/dq 2 -do-T (v+N)/dq 2 approaches a constant which is independent of the leptonic invariant 4-momentum transfer q 2 . Bjorken, 3 by an isospin rotation, has transformed the neutrinoreaction results into inequalities on electron-nucleon (or muon-nucleon) scattering which hold in the limit of infinite incident electron energy; these inequalities may make it feasible to test Eq. (la) in the near future.…”

Parity and Sign of theΣ+→n+π+Decay Amplitude and a Model forHippel1 1964Phys. Rev.23050View full textAdd to dashboardCite

“…(6.8) is a variational wave function for the A-nucleus correlation: F (r) -exp (-air 2 )+C exp (-a 2 r 2 ) (6.10) whose parameters have been chosen to obtain the binding energy 44 i?A(AHe 4 ) = 2.33 MeV in the Gaussian potential well of the core nucleus with radius R w given by where R v = 0.904 is the range of a Gaussian potential of the same intrinsic range as a Yukawa potential of range (2/x) -1 . 45 The parameters in Eq. (6.10) have the values ai = 0.214 F~2, a 2 = 0.0384 F~2, and C= 0.339.…”