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\title{Alfven-wDispersion}
\author{brandenb }
\date{January 2023}

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\section{Introduction}

\section{Theoretical Background}

\subsection{Reheating?}

The end of reheating in the early universe refers to a crucial period after cosmic inflation, a hypothetical rapid expansion that occurred shortly after the Big Bang. During inflation, the universe experienced exponential growth, stretching out its fabric and smoothing out irregularities.

Following inflation, the universe was dominated by an inflaton field—a scalar field responsible for driving inflation. As inflation ended, the inflaton field began to oscillate around the minimum of its potential energy. During these oscillations, the energy of the inflaton field is gradually converted into other particles, a process known as reheating.

Reheating is a significant phase in the early universe because it marks the transition from the inflationary phase to a radiation-dominated phase, setting the stage for the subsequent evolution of the universe. The energy transfer during reheating leads to the production of particles, such as photons, electrons, quarks, and other elementary particles, which eventually form the building blocks of matter.

The precise details of the reheating process depend on the specific particle physics model that describes the inflaton field and its interactions. In some models, reheating is primarily driven by the decay of the inflaton field into other particles. The inflaton field's decay can be a rapid or gradual process, leading to different reheating scenarios.

The end of reheating occurs when the energy transfer from the inflaton field to other particles is complete, and the universe becomes radiation-dominated. At this point, the energy density of the universe is dominated by the thermal radiation produced during reheating. The temperature of the universe is determined by the energy of these thermalized particles and sets the starting conditions for subsequent cosmological epochs, such as Big Bang nucleosynthesis and the formation of the cosmic microwave background radiation.

Understanding the end of reheating is crucial for cosmology as it connects the physics of inflation, particle physics, and the early universe. The precise mechanisms and timescales of reheating are still subjects of active research and depend on the details of the underlying particle physics model. The study of reheating provides insights into the fundamental processes that shaped the early universe and its subsequent evolution.


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