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Instructors: Prof. Dr. Julia Harz
Event type:
Lecture/practice class
Displayed in timetable as:
Hours per week:
4
Credits:
6,0
Language of instruction:
Englisch
Min. | Max. participants:
- | -
Requirements / organisational issues:
Helpful is knowledge from Theoretical Physics 6 (08.128.165) and Cosmology and General Relativity (08.128.732), as well as basic knowledge of the Standard Model of Particle Physics e.g. from The Standard Model and Electroweak Theory (08.128.742) or similar lectures such as Nuclear- und Particle Physics (08.128.055).
Contents:
This lecture focuses on cosmology of the early universe. First we will talk about the evolution of the early universe. Starting from the principles of homogeneity and isotropy, we will introduce the Friedmann-Lemaitre-Robertson-Walker metric describing the expansion of the universe. Linking to the Einstein Equations of General Relativity, we will then be able to describe the evolution of the matter and energy content of the universe and connect to experimental measurements today. We will learn about the so-called flatness and horizon problems, requiring some early time of accelerated expansion - inflation. We will discuss how inflation can solve these problems, how the introduction of a scalar field can aid, and how we can constrain inflationary models with experimental data. After the period of accelerated expansion, the universe is thought to go through a phase of reheating, leading to a hot plasma of particles in equilibrium. We will discuss the reheating period and talk about the thermodynamics of equilibrium including entropy and number densities of relativistic and non-relativistic species, relevant to describe concepts such as neutrino decoupling, baryogenesis or dark matter evolution. We will then be able to review the history of the universe including major events such as neutrino decoupling, Big Bang Nucleosynthesis, and recombination. From the time of the latter two events, we have a quantitative measure of the matter-antimatter asymmetry that requires a new mechanism - baryogenesis - to generate such a baryon asymmetry. Hence, we will learn in detail about the theoretical requirements (e.g. thermal out-of-equilibrium, CP violation, B-L violation) for baryogenesis, review the status of the standard model and understand why new physics is required. We will learn about two classes of baryogenesis, namely electroweak baryogenesis and leptogenesis bridging naturally to neutrino physics. The theoretical concepts learned in the context of leptogenesis (Boltzmann equations), will be similarly applicable for calculating the dark matter relic abundance. While so far having only focused on the homogeneous universe, we will look also into the inhomogeneous universe including primordial anisotropies from inflation, the anisotropies in the cosmic microwave background, and the impact of anisotropies on structure formation.
Goal of the lecture is to provide a broad but thorough overview of concepts of early universe cosmology and the status of current research. The course will prepare students with the necessary background to carry out supervised research in this field.
Recommended reading list:
The Early Universe, Kolb and Turner
Physical Foundations of Cosmology, Mukhanov
Modern Cosmology, Dodelson
Cosmology, Baumann
Cosmology, Weinberg
Additional information:
In case of overlap with other lectures, a change of the lecture time can be discussed in the first week.
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