### Quasiparticle

A quasiparticle is an excitation of a many-particle system that has an energy-momentum relation.

##### Explanation

Quasiparticles are characterized by the fact that they cannot occur outside their many-particle system. A quasiparticle is therefore not an elementary particle.

It is only a mathematical instrument to describe more easily the movement and interaction of particles in a solid.

##### Additional information

The concept of quasiparticles was developed by the Soviet physicist Lev Landau.