# The difference between spatial and intrinsic parity

1. Sep 30, 2015

### Coffee_

Can someone explain on the level of Griffiths QM what the difference between those two parities since I'm quite confused here. Some sources use the terms interchangably, some don't.

Could anyone provide good definitions for both terms?

Spatial parity seems pretty obvious to me to be the eigenvalue associated with an eigenstate of the position vector inversion.

2. Sep 30, 2015

### Andrea M.

In general the parity of a particle is the product of intrinsic and extrinsic (or spatial as you say) parity. Extrinsic parity is given by $(-1)^l$ where $l$ is the orbital angular momentum of the state. Intrinsic parity is peculiar of each particle and it simply says as the state of the particle change under a parity transformation:
$$P\vert \pi\rangle=\vert \pi\rangle\quad\text{for positive parity}$$
$$P\vert \pi\rangle=-\vert \pi\rangle\quad\text{for negative parity}$$

3. Oct 1, 2015

### Coffee_

Firs off, thanks for the answer.

Right,so the intrinsic parity is the eigenvalue of the operator that switches all the signs in the position wavefunction?

How does extrinsic parity relate to this operator and eigenvalue?

4. Oct 1, 2015

### ChrisVer

a single fundamental particle (like a single quark) will have intrinsic parity.
a composite or a group of particle(s) will have intrinsic parity (due to the constituents/members) + maybe extrinsic parity (due to the configuration of those particles).
The sign is just a matter of convention.