Bare particle

A bare particle is an excitation of an elementary quantum field in theoretical physics; in solid-state physics and particle physics, it becomes a dressed particle when it includes the additional particles surrounding it, often described as a quasiparticle in condensed-matter systems.

In the context of quantum field theory, bare particles are theoretical entities whose properties, such as bare mass and bare charge, are defined in the absence of interactions with their own fields. In renormalization theory, these parameters often differ from physical (observed) values because of the "cloud" of the virtual particles surrounding the particle.