New results on the 8Be anomaly

A J Krasznahorkay,I Vajda,Á Nagy,M Csatlós,J Timár,N Sas,T G Tornyi,Z Gácsi,L Csige,J Gulyás

doi:10.1088/1742-6596/1056/1/012028

Abstract

Recently, we observed anomalous internal pair creation for the M1 transition depopulating the 18.15 MeV isoscalar 1+ state in 8Be. We observed a significant (σ = 7.37) peak-like deviation from the predicted angular correlation of the e+ e pairs at θ = 140°. To the best of our knowledge no nuclear physics related description of such deviation can be made. However, the deviation can be described by assuming the creation and subsequent decay of a boson with mass of ≈17 MeV. In order to clarify the interpretation, we re-investigated the 8Be anomaly with an improved, and independent setup. We have confirmed the signal of the assumed X(17) particle and constrained its mass (m0c2 = 17.01(16) MeV) and branching ratio compared to the γ-decay (Bx = 6(1) × 10−6).

Highlights

Our current knowledge of Nature at the fundamental level is successfully explained by the Standard Model (SM) of elementary particles, but this theory describes only five percent of the entire content of the Universe
We have confirmed the signal of the assumed X(17) particle and constrained its mass (m0c2 = 17.01(16) MeV) and branching ratio compared to the γ-decay (Bx = 6(1) × 10−6)
A complementary and vital role is played by low-energy, precision and/or high-intensity experiments, which require a joint effort of the particle, atomic, and nuclear physics communities [1, 2]

Summary

Introduction

Our current knowledge of Nature at the fundamental level is successfully explained by the Standard Model (SM) of elementary particles, but this theory describes only five percent of the entire content of the Universe. We have confirmed the signal of the assumed X(17) particle and constrained its mass (m0c2 = 17.01(16) MeV) and branching ratio compared to the γ-decay (Bx = 6(1) × 10−6). Observations of rare nuclear transitions can be used to search for new hidden force-carrier particles at the MeV scale.

Results

Conclusion