Doctoral Defense in Physics - Alexia Nix

Link on Zoom:
https://eu01web.zoom.us/j/67917113047

Doctoral candidate:
Alexia Nix

Title of thesis:
Gravity, Holography and Deformations

Opponents:
Dr. Joseph A. Minahan, Professor at the Department of Mathematics, Uppsala University, Sweden
Dr. Silvia Penati, Professor at the Department of Physics, University of Milano-Bicocca, Italy

Advisor:
Dr. Valentina Giangreco M. Puletti, Professor at the Faculty of Physical Sciences, University of Iceland

Other members of the doctoral committee:
Dr. Fridrik Freyr Gautason, Lecturer in String Theory at the school of mathematical sciences, University of Southampton, United Kingdom (Main Supervisor)
Dr. Watse Sybesma, Assistant Professor of Theoretical Physics, Nordic Institute of Theoretical physics (NORDITA), Sweden
Dr. Lárus Thorlacius, Professor of Theoretical physics at the Faculty of Physical Sciences, University of Iceland
Dr. Konstantin Zarembo, Professor of Theoretical Physics at the Faculty of Science, Niels Bohr Institute (NBI) and Nordic Institute of Theoretical physics (NORDITA), Denmark and Sweden

Chair of Ceremony:
Dr. Birgir Hrafnkelsson, Professor and Head of the Faculty of Physical Sciences, University of Iceland

Abstract:
In this dissertation we aim to explore gravity using two different methods, namely precision holography and stress-tensor deformations. From the holographic perspective we achieve this by studying the holographic dual of the half-BPS Wilson loop operator, in a variety of both conformal and non-conformal field theories, which is given by the partition function of a fundamental string or probe M2-brane in the corresponding dual geometry. We do this by focusing on the first subleading correction of the corresponding holographic expansion. This way we provide new quantitative tests of these gauge/gravity dualities, and we further develop the tools that are necessary for such an analysis. On the other hand, we utilize the massive gravity formulation of stress-tensor deformations to establish new connections with various theories of gravity, as well as mathematics. In particular, using this formulation we construct a new d-dimensional deforming operator that extends the findings of previous holographic studies, and makes contact with earlier results of minimal massive gravity. In three dimensions, we study the stress-tensor deformation of a certain seed theory and recover the DBI action of a two-brane in Polyakov form as the deformed action, establishing a new connection to string theory. Finally, restricting our analysis to two dimensions we show how the study of some deformed theories, that satisfy certain properties, can lead to further insights regarding the algebraic properties of special functions.

About the doctoral candidate:
Alexia completed her undergraduate studies in Physics at the University of Crete, Greece in 2020. After that she moved to Sweden, where she obtained a Master’s degree in Theoretical Physics at Uppsala University. In 2022, she started pursuing a doctoral degree in Physics at the University of Iceland under the supervision of Friðrik Freyr Gautason.