The symmetry of the in-group particles, which are of three generation fermions, and the
“out-group”ones, which are not admitted by three generation fermions, was discussed. Itwas found
that the“out-group”antiparticles of Bose type, which came into being because of CP ( charge
conjugation-parity conservation) violation in the early universe and became heavier due to the phase
transformation from low temperature to high temperature, are the supersymmetry companionsof the“in-
group”particles of Fermi type. The mass of a neutralino, which is the lightest particle of the
supersymmetry companions andmay be ofdarkmatter, was calculated to be about320 GeV. The ratio
of the number density ofphotons to thatofprotons calculatedwith Planck distributionmethod is about
0. 6×1010, which is close to the observed value (about1010) available in literature. A photon has the
quark-gluon structure according to an analysisof the relationship between itsmass and structure, which
is consistentwith the experimental result reported in literature.