The effect Δ of the Coulomb interaction on the Λ separation energy of was obtained by variational calculations made for and . These calculations were made for several values of in the range 0≤≤9 where qe is the proton charge, i.e., the Coulomb repulsion was artificially boosted. For ≲3, the dependence on is linear, and interpolation to =1 gives the physical values with improved accuracy: -Δ=0.05±0.02 and 0.025±0.015 MeV for the ground and excited state, respectively. This procedure also gives more accurate values for the differences between the proton and neutron radii of . The corresponding differences of between and , to be attributed to charge symmetry breaking effects, are then 0.40±0.06 and 0.27±0.06 MeV. From these values we obtain a phenomenological charge symmetry breaking potential which is effectively spin independent. An examination of meson-exchange charge symmetry breaking models shows that these are consistent with the phenomenological charge symmetry breaking potential for the triplet but not for the singlet case.
- Received 27 August 1984
- Published in the issue dated April 1985
© 1985 The American Physical Society