Explain annihilation in the vacuum?

Question

anonymous · Answer

Annihilation is when a particle and its corresponding antiparticle collides. Because their quantum numbers are equal and opposite, their state sums to zero. Due to conservation of energy and momentum, there must be resultant energy and momentum from the collision, and so any possible set of particles whose states sum to zero can be produced. With lower-energy collisions, massless photons are "favored"; as you get higher, heavier force-carrier particles are generated.

anonymous · Answer

I want to know the situation in vacuum?

anonymous · Answer

I think I already described vacuum.