  Annihilation of superheavy particles in primordial bound systems is
considered as the source of Ultra High Energy Cosmic Rays (UHECR).Charge
conservation makes them to be produced in pairs, and the estimated separation
of particle and antiparticle in such pair is shown to be in some cases much
smaller than the average separation determined by the averaged number density
of considered particles. If the new U(1) charge is the source of a long range
field similar to electromagnetic field, the particle and antiparticle,
possessing that charge, can form primordial bound system with annihilation
timescale, which can satisfy the conditions, assumed for this type of UHECR
sources. These conditions severely constrain the possible properties of
considered particles. So, the proposed mechanism of UHECR origin is impossible
to realise, if the U(1) charged particles share ordinary weak, strong or
electromagnetic interactions. It makes the proposed mechanism of pairing and
binding of superheavy U(1) charged particles an effective theoretical tool in
the probes of the physics of very early Universe and of the hidden sector of
particle theory, underlying it.
