Axions in the Universe - LATE PROJECT

This fully funded project is dedicated to axions and axion-like particles and their role in cosmology and astrophysics. Axions are very popular hypothesized pseudo-scalar particles with a number of attractive properties for particle physics, astrophysics and cosmology, for review see [1,2,3]. Axions originated from studies of quantum chromodynamics (QCD) to solve the notorious strong CP problem. One of the defining features of axions is that their mass and the low-energy interactions are suppressed by requirements of classical shift-symmetry. In this project we will investigate possible axion gravitational couplings, see e.g. [6] and their influence on black holes and other compact objects like in [3,4,5] along with their role in axion inflation and alternatives to inflation. We will also investigate axions as dark matter, focusing on their production mechanisms, topological defects like domain walls and potential observational signatures including gravitational waves. During the project the student will also learn CosmoLattice code [7] (and potentially other codes for simulations in classical field theory). Thus, it is an advantage if the candidate knows C++ and can demonstrate programming skills.

This project involves broad international collaboration with France, Japan, South Korea and the USA.

References:

[1] Jihn E. Kim, G. Carosi, Axions and the Strong CP Problem, Rev.Mod.Phys. 82 (2010) 557–602, • e-Print: 0807.3125
[2] Jihn E. Kim, Light Pseudoscalars, Particle Physics and Cosmology, Phys.Rept. 150 (1987) 1–177
[3] A. Arvanitaki, S. Dimopoulos, S. Dubovsky, N. Kaloper, J. March-Russell, String Axiverse, Phys.Rev.D 81 (2010) 123530 • e-Print: 0905.4720 [hep-th]
[4] A. Arvanitaki, S. Dubovsky, Exploring the String Axiverse with Precision Black Hole Physics Phys.Rev.D 83 (2011) 044026 • e-Print: 1004.3558 [hep-th]
[5] D. Doneva, F. Ramazanoğlu, H.Silva, T. Sotiriou, S. Yazadjiev, Scalarization, e-Print: 2211.01766 [gr-qc]
[6] R. Kallosh, A. Linde, D. Linde, L. Susskind, Gravity and global symmetries, Phys.Rev.D 52 (1995) 912–935 • e-Print: hep-th/9502069 [hep-th]
[7] https://cosmolattice.net/; „CosmoLattice: A modern code for lattice simulations of scalar and gauge field dynamics in an expanding universe“, D. G. Figueroa, A. Florio, F. Torrenti and W. Valkenburg, Comput. Phys. Commun. 283 (2023), 108586; • e-Print:2102.01031; „Present and future of CosmoLattice“ D. G. Figueroa, A. Florio and F. Torrenti, Present and future of CosmoLattice; • e-Print: 2312.15056.