Question

Part A

Which of the following are different for a particle and its antiparticle?

charge only

mass only

spin only

charge and mass

charge and spin

mass and spin

charge and mass and spin

Part B

Which conservation law is violated by particle-antiparticle annihilation?

conservation of energy

conservation of momentum

conservation of charge

conservation of lepton number

none of these

Answer 1

A - Antinparticles: Particle having the same mass, spin, isospin as a particle, but having all additive quantum numbers opposite to those of its respective particle. Antiparticles have the opposite charge of its corresponding particle.

Thus only charge will be different for a particle and antiparticle.

B - In quantum field theory, particle-antiparticle annhilation process is allowed only as an intermediate quantum state for times short enough that the violation of energy conservation can be accommodated by the uncertainty principle.Now the conservation of momentum is also conserved. The charge is conserved and it remains zero as initial and final. Again the lepton's number is also conserved and Thus last option is correct.