# What is a particle in quantum mechanics?

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1. Nov 9, 2014

### arupel

I would imagine that there are different viewpoints of what a particle is in quantum mechanics. Is it possible to get a summary of what they are?

2. Nov 9, 2014

### Matterwave

Something that is detected by a particle detector, i.e. something that shows up as a dot on a screen, or some such.

3. Nov 9, 2014

### VantagePoint72

A discrete excitation of a quantum field which is characterized by the eigenvalues of some set of conserved operators (e.g. charge, mass, and spin). They are often, but not necessarily, well-localized in space.

4. Nov 10, 2014

### dextercioby

The definition in post#3 reminds me of the famous one by E.P. Wigner which can be recast as: A particle is a quantum state in the (rigged) Hilbert space which carries an irreducible representation of the universal covering group of the restricted Poincare group.