In the context of the Big Bang theory and the early universe, the exact details of matter-antimatter annihilations and the formation of quarks and antiquarks are still areas of active research and ongoing investigation. Our understanding of these processes is based on theoretical models and experimental data.
According to current cosmological models, during the early stages of the universe, the energy density was extremely high, and the temperatures were incredibly hot. Under such extreme conditions, particle-antiparticle pairs could be spontaneously created and annihilated. This process is described by quantum field theory.
As the universe expanded and cooled, it underwent a phase transition known as the quark-hadron transition. During this transition, the energy density and temperature dropped to a point where quarks and antiquarks could bind together to form hadrons, such as protons and neutrons. This process is referred to as hadronization.
The exact mechanisms and timing of matter-antimatter annihilations during this early period are still the subject of ongoing research. However, it is generally believed that as the universe continued to expand and cool, the annihilation processes became less frequent, and the abundance of matter particles, such as protons and neutrons, began to dominate over antimatter particles.
The observed imbalance between matter and antimatter in the universe today is one of the fundamental puzzles in cosmology. It is an active area of research to understand why the universe seems to have a preference for matter over antimatter, which ultimately led to the formation of the structures we observe today, including galaxies, stars, and ultimately, life as we know it.