### Master-Pflichtseminar --- Summer term 2015

# About the seminar

## Here is the plan

In a first course on Quantum Field Theory (QFT) the background spacetime is taken to be flat Minkowski space, which is appropriate to make predictions for collider experiments. However, in cosmological contexts spacetime curvature cannot always be ignored and an understanding of quantum fields in such backgrounds is necessary.

In this seminar we will study QFT in curved spacetimes such as expanding *Friedmann-Robertson-Walker* geometries or *de Sitter* space. We will discover that notions such as a "particle" or the "vacuum" become ambiguous and observer dependent. Our findings are important for the understanding of early universe cosmology: one application is the calculation of *density perturbations* arising from *inflation*. The ultimate goal of this seminar will be to derive the effect of *Hawking Radiation* of black holes as well as the *Unruh effect*.

## Prerequisites

- Quantum Field Theory: an understanding of QFT at the level of QFT-1 is essential.
- General Relativity / Differential Geometry: previous exposure to General Relativity or Differential Geometry is definitely helpful.

## References

Here is a list of books which will be useful references for many presentations:

- Our main reference will be the lecture notes by Sergei Winitzki [
**W**]. - There is also a textbook based on these notes: Viatcheslav Mukhanov and Sergei Winitzki [
**MW**],*Introduction to Quantum Effects in Gravity*, Cambridge University Press, 2007. - A standard reference is N.D. Birrell, P.C.W. Davies [
**BD**],*Quantum Fields in Curved Space*, Cambridge University Press, 1982. It is a bit dated in places. - A more modern version cobering the same topics is L.E. Parker and D.J. Toms [
**PT**],*Quantum Field Theory in Curved Spacetime*, Cambridge University Press, 2009. - An introduction to axiomatic QFT in Curved Spacetimes can be found in R.M Wald,
*Quantum Field Theory in Curved Spacetime and Black Hole Thermodynamics*, The University of Chicago Press 1994. I listed this for completenes, but this source will not be too relevant for this seminar. - A wealth of useful resources, particularly on Black Hole Thermodynamics, the Black Hole Information Paradox and the Firewall discussion can be found on the following course websites: Introduction to Quantum Field Theory in Curved Spacetime at the University of Bern, Advanced GR and QFT in curved spacetime at McGill University.

## Topics

## Schedule

Date |
Speaker |
Topic |
References / Notes |

15 April | L. Witkowski | Organisational meeting | -- |

22 April | No meeting | Reading week | -- |

29 April | Christoph Sünderhauf | Scalar fields in FRW space | Notes |

06 May | Philipp Gernandt, Javier Gonzalez |
Am I a particle - and if so, how many? | Notes |

13 May | Benjamin Freist, Linda Shen |
Fluctuations | Notes |

20 May | Martin Klassen, Roland Walz |
de Sitter space | Notes |

27 May | Nils Fischer, Oscar Garcia |
Introducing Inflation | Notes |

03 June | Alberto Bailoni, Johannes Dombrowski |
Quantum Fluctuations during Inflation | Notes |

17 June | Ingolf Bischer, Nasim Rahaman |
The Unruh effect | Notes |

19 June | Julius Eckhard, Max Lautsch |
Particle emission by black holes | Notes |

24 June | Simon Hirscher, Dennis Stock |
The Black Hole Information paradox | Notes |

01 July | Emanuele Ottino, Maria Walch |
Firewall Paradox | Notes |

08 July | Sebastian Borszcz, Daniel Jimenez |
Axions and Cosmology | Notes |

15 July | Daniel Geiss, Daniel Kläwer |
The Weak Gravity Conjecture | Notes |

16 July | Torsten Zache | Inroduction to Loop Quantum Gravity | Notes |

22 July | Aleksandr Chatrchyan, Björn Jüliger |
Randall-Sundrum models | Notes |