QED2 boson description of the X17 particle and dark matter.

The oscillations of the color charges and electric charges of the quark and antiquarks of the underlying vacuum in a flux tube generate QCD2 bosons (mesons) and QED2 bosons (Phys.Rev.C81,064903(2010)). The predicted mass of the isoscalar QED2 boson in the flux tube environment is close to the X17 mass, leading to the suggestion that the X17 particle may be the isoscalar $I(J^\pi)$=0(0$^-$) QED2 boson arising from the oscillation of the electric charges of the quarks and antiquarks of the vacuum in the flux tube that mediates the meson-exchange interaction between the nucleon and the nuclear core in the excited 0(0$^-$) state of $^4$He. The isoscalar 0(0$^-$) QED2 boson can decay into an electron-positron pair or two photons in free space but the decays will be inhibited if the gravitational binding energy of the QED2 boson bound in a QED2 boson assembly exceeds its rest mass. Consequently, a self-gravitating isoscalar QED2 boson assembly whose mass $M$ and radius $R$ satisfy $(M/M_\odot)/(R/R_\odot) \gtrsim 4.71 \times 10^5$ will not produce electron-positron pairs or photons and may be a good candidate for a primordial dark matter.