[4] In 2015, Krasznahorkay and his colleagues at ATOMKI, the Hungarian Institute for Nuclear Research, posited the existence of a new, light boson with a mass of about 17 MeV/c2 (i.e., 34 times heavier than the electron).
[4] Feng et al. (2016)[7] proposed that a "protophobic" X boson, with a mass of 16.7 MeV/c2, suppressed couplings to protons relative to neutrons and electrons at femtometre range, could explain the data.
[8] This was covered in science journalism, focusing largely on the implications that the existence of the X17 particle and a corresponding fifth force would have in the search for dark matter.
The workshop discussed the ATOMKI anomaly and its theoretical interpretation and future experiments to confirm and explain it.
[23] As of December 2019[update], the ATOMKI paper describing the particle has not been peer reviewed and should therefore be considered preliminary.