Particle Physics
Particle Physics and Its Theoretical Foundations
Particle physics, often referred to as high-energy physics, is a branch of physics that investigates the fundamental particles and the forces with which they interact. These particles are the building blocks of the universe, and understanding their behavior and properties allows scientists to explore the nature of matter and energy.
The Standard Model*
At the core of particle physics is the Standard Model of particle physics, a comprehensive theory that describes three of the four known fundamental forces in the universe: the electromagnetic force, the weak nuclear force, and the strong nuclear force. The Standard Model is a gauge theory based on the symmetry group SU(3) × SU(2) × U(1).
The Standard Model characterizes the basic constituents of matter into two categories: fermions, which include quarks and leptons, and bosons, which are force carriers. The Higgs boson, discovered in 2012, is a pivotal component of the Standard Model, providing a mechanism by which particles acquire mass.
Quantum Field Theory*
The theoretical foundation of the Standard Model lies in Quantum Field Theory (QFT). QFT merges classical field theory with quantum mechanics and special relativity, offering a framework to describe the interactions of subatomic particles. In QFT, particles are viewed as excited states of underlying quantum fields.
Several specialized forms of QFT have been developed to address different aspects of particle physics. Electroweak theory, for example, unifies electromagnetic and weak interactions, while Quantum Chromodynamics (QCD) describes the strong force. These models are instrumental in making precise predictions that can be tested in experiments, such as those conducted at the Large Hadron Collider.
Phenomena and Interactions
Particle physics explores various phenomena, including flavour physics, which investigates the types and transformations of particles, and wave–particle duality, a core concept of quantum mechanics that posits that every particle or quantum entity exhibits both particle and wave properties.
Another intriguing area is the parton model, developed by Richard Feynman, which provides insights into the structure of hadrons, composite particles made of quarks.
Beyond the Standard Model
Despite its successes, the Standard Model is not a complete theory of fundamental interactions. It does not incorporate gravity, the fourth fundamental force, and cannot account for dark matter or dark energy. Consequently, physicists are developing theories beyond the Standard Model, such as Supersymmetry (SUSY) and string theory, which aim to provide a more comprehensive understanding of the universe.