Abstract

Quantum field theory (QFT) is one of the most successful and rigorously tested areas in all of physics. Central to this discipline is the notion of a particle as an excitation in a field. In fact, the central idea of QFT may be stated as: all particles are excitations in a quantum field (Lancaster and Blundell 2014). QFT is the only known method of combining quantum mechanics and special relativity. Moreover, as soon as quantum mechanics and relativity are combined, it becomes impossible to deal with single particles, and we are forced to consider the physics of collections of many particles. As a result, QFTs describe not only the relativistic realm of the standard model of particle physics but also the multiparticle realm of condensed matter physics, including the sub-disciplines of (quantum mechanical) hard matter and (the classical statistics of) soft matter. This variety allows a number of insights into cases where candidate emergent phenomena might be found. In this chapter we discuss the emergence of the properties of interacting particles, followed by the emergence of qualitatively new forms of particles. Our aim is to track how interactions lead directly to the physical masses and charges of particles in QFT and how they bring about states of matter that support the existence of novel forms of particles.