# ASTROPARTICLE PHYSICS

## Learning outcomes of the course unit

To learn fundamentals of Cosmology and Astroparticle Physics: energy scales, physical principles, strong and weak points of the proposed theoretical explanations.

To familiarize with computational tools of relevant physical quantities: quantum field theory in vacuum and at finite temperature, cross sections, decay rates, cosmological perturbations (hints). Emphasis will be given to the use of dimensional analysis and approximation methods, as preliminary steps towards a rigorous computation (when needed).

Developing skills to deal with new subjects independently: astroparticle physics is inherently an interdisciplinary subject, and to understand progresses in this field, and to contribute to them, a strong spirit of initiative and independence is needed.

Developing communication skills, through the writing of short scientific reports and oral presentations.

The course will be mostly self-cointained. Basic knowledge of quantum mechanics, statistical mechanics, and special relativity are required.

## Prerequisites

The course will be mostly self-cointained. Basic knowledge of quantum mechanics, statistical mechanics, and special relativity are required.

## Course contents summary

Astroparticle Physics sees the Universe as a big laboratory for fundamental Physics, in which theories can be tested. Observations at all scales are taken into account, from cosmological to stellar ones, down to terrestrial laboratories. Correspondingly, the theoretical tools required to deal with this subject are diverse, including quantum mechanics, relativistic field theory, special and general relativity, the standard model of particle physics and cosmological models.

The course will introduce, in a self-contained way, both theoretical and observational elements, giving particular emphasis on most recent developments, on open questions, and future perspectives.

## Course contents

0) INTRODUCTION:

What we know about the Universe: observational methods, properties, relevant scales.

2) THEORETICAL TOOLS:

Fundamental interactions in our Universe:

- gravity and the general theory of relativity (basics);

- basics on the standard model of particle physics;

- hints on nuclear physics.

Cross sections and decay rates.

Dimensional analysis and approximation methods.

2) BIG BANG AND INFLATION

Thermal history of the Universe.

Relics from the primordial Universe: photons, neutrinos, gravitational waves.

Other possible relics: cold, warm and hot.

Primordial photons and cosmic microwave background (CMB): origin and characteristics. CMB as the perfect cosmological observable. Standard cosmological model.

Cosmological Inflation

- problems of the Big Bang;

- the inflationary solution;

- inflation and the origin of cosmological structures.

3) NEUTRINOS

Neutrino properties: interactions, masses and oscillations

Neutrino production: laboratory, stars, Universe.

Big Bang nucleosynthesis.

Baryon-antibaryon asymmetry and its possible explanations

Neutrinos from supernovae

4) DARK ENERGY AND DARK MATTER

Evidences

Properties of Dark Matter and Dark Energy, and their role in the Universe.

Possible explanations of Dark Matter

Research strategies of Dark Matter: direct, indirect, and laboratory searches.

Theoretical models for Dark Energy and their problems.

## Recommended readings

E.W. Kolb, M.S. Turner: "The Early Universe" (Addison Wesley)

S. Weinberg: "Gravitation and Cosmology" (Wiley)

P.J.E. Peebles: "Principles of Physical Cosmology" (Princeton University Press)

S. Dodelson: "Modern Cosmology" (Academic Press)

Gorbunov, Dmitry S.; Rubakov, Valery A., Introduction to the Theory of the Early Universe: Hot Big Bang Theory. Singapore: World Scientific Publishing Company

Bergstrom, Lars; Goobar, Ariel, Cosmology and particle astrophysics. Berlin: Springer

Perkins, Donald H., Particle astrophysics. Oxford: Oxford University Press

J. Lesgourgues, G. Mangano, G. Miele, S. Pastor: "Neutrino Cosmology" (Cambridge University Press)

Giunti, Carlo; Kim, Chung Wood, Fundamentals of neutrino physics and astrophysics. Oxford: Oxford University press, 2007

## Teaching methods

Frontal lessons.

## Assessment methods and criteria

A short report, written as a scientific article, on a subject agreed with the lecturer, will be required. Then, there will be, an oral examination on the subjects covered during the course and on the subject of the written report.

The final evaluation will be based 50% on the written report and 50% on the oral examination.