Gamma-ray spectroscopy of single Λ-hypernuclei at J-PARC: results and perspective.

Experimental results from the J-PARC E13 experiments are summarized. A new experimental set up of E13 has established a platform for the future γ-ray hypernuclear spectroscopy at J-PARC using kaon beams. New γ rays are identified in ⁴_ΛHe and ¹⁹_Λ F. The energy of 1.406 MeV for the ⁴_ΛHe(1⁺→0⁺) transition confirmed a sizable effect of Charge Symmetry Breaking (CSB) in ΛN interaction in the A=4 hypernuclear system. The identification of four γ rays in ¹⁹_Λ F is made for the first time in sd shell hypernuclei. Especially, energy spacing of the ground state doublet is found to be 315.5 keV. A good agreement with two theoretical calculations suggests that the theoretical formalism used in p shell hypernuclei is also applicable to heavier hypernuclei. Lastly, an overview of the future J-PARC E63 experiment is given. [ABSTRACT FROM AUTHOR]