In quantum field theory (QFT), particles are described as excitations of quantum fields. These fields permeate all of space and time and interact with one another to create and annihilate particles. The process of particle creation and destruction in QFT is described by the mathematical framework known as second quantization.
In QFT, each type of particle is associated with a specific field. For example, the electromagnetic field is associated with photons, the electron field is associated with electrons, and so on. These fields are represented by operators that create and annihilate particles. The creation operator adds a particle to a particular state of the field, while the annihilation operator removes a particle from that state.
The dynamics of particle creation and destruction are governed by the fundamental principles of quantum mechanics, including the principles of superposition and the uncertainty principle. According to these principles, the quantum fields can exist in various states, each corresponding to a different number and arrangement of particles.
In a process of particle creation, an interaction or energy input can cause the quantum field to transition from a state with a certain number of particles to a state with a different number of particles. This transition involves the creation operator acting on the field to add a particle. The specific details of particle creation depend on the specific interaction and the properties of the fields involved.
Similarly, in particle destruction or annihilation, an interaction or energy loss can cause the field to transition from a state with a certain number of particles to a state with a different number of particles. This transition involves the annihilation operator acting on the field to remove a particle.
It's important to note that in QFT, particles are not seen as independent entities moving through space in a classical sense. Instead, they are treated as excitations of the underlying quantum fields. The fields themselves are the fundamental entities, and particles are manifestations of their excitations.
The mathematical framework of QFT provides a powerful description of particle creation and annihilation and allows for the calculation of probabilities and amplitudes associated with these processes. It has been highly successful in describing a wide range of phenomena in particle physics and has been extensively tested through experiments and observations.