In contrast, it doesn't affect the mass, linear momentum or spin of a particle.
that transforms a particle into its antiparticle, Both states must be normalizable, so that which implies that
Putting this all together, we see that meaning that the charge conjugation operator is Hermitian and therefore a physically observable quantity.
For the eigenstates of charge conjugation, As with parity transformations, applying
twice must leave the particle's state unchanged, allowing only eigenvalues of
In a pair of bound mesons there is an additional component due to the orbital angular momentum.
For example, in a bound state of two pions, π+ π− with an orbital angular momentum L, exchanging π+ and π− inverts the relative position vector, which is identical to a parity operation.
Under this operation, the angular part of the spatial wave function contributes a phase factor of (−1)L, where L is the angular momentum quantum number associated with L. With a two-fermion system, two extra factors appear: One factor comes from the spin part of the wave function, and the second by considering the intrinsic parities of both the particles.
Note that a fermion and an antifermion always have opposite intrinsic parity.