136Sn and three-body forces
New experimental data on 2+ energies of 136,138Sn confirm the trend of lower 2+ excitation energies of even–even tin isotopes with N>82 compared to those with N<82. However, none of the theoretical predictions using both realistic and empirical interactions can reproduce experimental data on excitation energies as well as the transition probabilities (B(E2;6+→4+$B(E2; 6^{+} \rightarrow 4^{+}$)) of these nuclei, simultaneously, apart from the ones whose matrix elements have been changed empirically to produce mixed seniority states by weakening the pairing. We have shown that the experimental result also shows good agreement with the theory in which three-body forces have been included in a realistic interaction. The new theoretical results on transition probabilities are discussed to identify the experimental quantities which will clearly distinguish between different views.