True Leptonium ($l^{+}{l}^{-}$) Production in UPC Triphoton Interaction

Qi-Ming Feng, Qi-Wei Hu, Cong-Feng Qiao

True leptonium states ($l^{+}{l}^{-}$) are compact pure QED systems, first theoretically predicted eight decades ago. Although considerable efforts have been devoted to their search, on…