Observation of Anomalous Internal Pair Creation in Be 8: A Possible Indication of a Light, Neutral Boson

A. J. Krasznahorkay, M. Csatlós, L. Csige, Z. Gácsi, J. Gulyás, M. Hunyadi, I. Kuti, B. M. Nyakó, L. Stuhl, J. Timár, T. G. Tornyi, Zs Vajta, T. J. Ketel, A. Krasznahorkay

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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 Be8. 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 >5σ. 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.

Original languageEnglish
Article number042501
JournalPhysical review letters
Volume116
Issue number4
DOIs
Publication statusPublished - jan. 26 2016

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

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