X17: Searching for New Physics in Nuclear Transitions

by Attila Krasznahorkay (CERN, Inst. of Nucl. Res. (ATOMKI))


The study of the de-excitation of 8Be through the emission of e+e- pairs found an anomaly in the angular correlation spectrum of the electrons [Phys. Rev. Lett. 116, 052501 (2016)]. One that can possibly be explained by the existence of a yet unknown (bosonic) particle. A new measurement, with a re-built experimental setup, studying the angular correlation of e+e- pairs coming from the de-excitation of 4He provided a similar anomaly [arXiv:1910.10459 (nucl-ex)]. One that may be explained by the existence of the same mXc2 = 16.84 ± 0.16 (stat) ± 0.20 (syst) (X17) particle. The talk will review the experiments performed at the Institute for Nuclear Research (Atomki, http://www.atomki.hu/en/), describe the data analysis, and discuss the possible interpretations of the results.