# What type of symmetry specifies in presence of what each not-charged particle (for example, neutrino) should have an antiparticle?

I think that charging symmetry assumes antiparticle presence, which has an opposite charge sign . And what symmetry assumes existence of an antiparticle at a neutral particle

-
See also this question. –  Peter Shor Dec 2 '11 at 1:00
Would it be possible to clarify the question title? And the question body, for that matter? I don't quite understand what it's asking... –  David Z Dec 2 '11 at 9:39

Anti-matter is not just the opposite charge sign. To convert matter to anti-matter you apply the C-parity operation which change more quantum numbers than just charge. In the case of the neutrino the lepton number is switched,

-
But Majorana neutrinos are their own antiparticles. –  Peter Shor Dec 2 '11 at 1:02
Further, lepton number is not conserved. –  Ron Maimon Aug 23 '12 at 5:55