What is a particle in quantum mechanics?

[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?

 

[Matterwave]

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

 

[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.

 

[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.