A Deviation In Internal Pair Conversion

The E1 e(+)e(-) decay of the 17.2 MeV level in C-12, and the M1 e(+)e(-) decay of the 17.6 MeV level in Be-8 have been studied in a search for possible signals of short-lived neutral bosons with masses between 5 and 15 MeV/c(2). Whereas for the E1 decay at large correlation angles no deviation is found from internal pair conversion (IPC), surprisingly the M1 angular correlation deviates from IPC at the 4.5 sigma level.