Is Phase Relevant for Uncharged Particles?

[LarryS]

Global phase invariance has been identified with the conservation of electric charge. Local phase invariance via the coupling of the wave function/field with the EM four-vector has been identified with charged particles interacting with the EM field.

Am I correct in assuming that, except for interference effects, Phase is basically irrelevant for uncharged particles?

Thanks in advance. Physics for me is neither a major nor a profession, just an interest.

 

[mfb]

Absolute phases are always irrelevant. There are several symmetries, leading to the different charges (electric, weak (those can be combined to the weak hypercharge), color).
Phase differences can matter, depending on what you are looking at - but only for particles interacting, which means they need the charge of whatever interaction you are looking at.