# Difference between a neutrino and an antineutrino

Hi all.
What is the difference between a neutrino and an antineutrino if they both have no charge and aren't made up of quarks?
Thanks.

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malawi_glenn
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How they interact with other weak interacting particles.

They "carry" lepton familiy number, which is something that must be conserved in an interaction.

for example:

allowed:
$$\overline{\nu} _{\mu} + u \rightarrow \mu ^+ + d$$

Not allowed:
$$\nu _{\mu} + u \rightarrow \mu ^ + + d$$

where u and d are up- and down- quarks.

in the first reaction, initial muon-family number is -1, and final muon-family number is -1 (since antiparticles has -1, and particles has +1, postive charged leptons are defined to be antiparticles, and negative charged leptons is then particles.)

in the secon reaction, initial muon-family number is +1, and final muon-family number is -1

blechman
Hi all.
What is the difference between a neutrino and an antineutrino if they both have no charge and aren't made up of quarks?
Thanks.
It is interesting to note that IF the neutrinos have MAJORANA masses rather than DIRAC masses, then there is NO difference between a neutrino and an antineutrino! This is an open question in the particle physics community. Malawi-Glenn rightfully points out a potential experiment to test and see if the neutrino is Majorana or Dirac - if it's Majorana it would necessarily violate lepton number as his "forbidden" interaction would now be allowed. People are looking...

malawi_glenn