Observation of Anomalous Internal Pair Creation in 8Be: A Possible Indication of a Light, Neutral Boson
Abstract
Electron-positron angular correlations were measured for the isovector magnetic dipole 17.6 MeV (Jπ=1+, T =1 ) state→ground state (Jπ=0+, T =0 ) and the isoscalar magnetic dipole 18.15 MeV (Jπ=1+, T =0 ) state→ground state transitions in 8Be. Significant enhancement relative to the internal pair creation was observed at large angles in the angular correlation for the isoscalar transition with a confidence level of >5 σ . This observation could possibly be due to nuclear reaction interference effects or might indicate that, in an intermediate step, a neutral isoscalar particle with a mass of 16.70 ±0.35 (stat)±0.5 (syst) MeV /c2 and Jπ=1+ was created.
- Publication:
-
Physical Review Letters
- Pub Date:
- January 2016
- DOI:
- 10.1103/PhysRevLett.116.042501
- arXiv:
- arXiv:1504.01527
- Bibcode:
- 2016PhRvL.116d2501K
- Keywords:
-
- Nuclear Experiment
- E-Print:
- 5 pages, 5 figures