Midway Evaluation in Physics - Matthias Harksen

Name of thesis: Non-Lorentzian symmetries and black holes

Student: Matthias Harksen

Doctoral committee:
Dr. Lárus Thorlacius, Professor at University of Iceland, Dr. Zhao-He Watse Sybesma, Assistant Professor at Nordita & Stockholm University, Sweden, Dr. Valentina Giangreco, Professor at University of Iceland, Dr. Friðrik Freyr Gautason, Assistant Professor at University of Southampton, UK, Dr. Niels Obers, Professor at University of Copenhagen, Denmark

Abstract:
I will present my PhD research for the past two years which has been focused on consider- ing what happens when we digress away from relativistic symmetries towards non-Lorentzian symmetries specifically in the framework of black holes and string theory. I will talk about the main results of my two latest papers. In the first paper we consider the Carroll-limit of traditional bosonic string theory. Our Carroll-string describes the movement of strings in the vicinity of black hole horizons and allows for transverse movement in contrast to most Carrollian theories which do not allow for movement in spatial directions. In the second paper we consider the mass-gap puzzle for a near-extremal Lifshitz-like black hole. We show that its dynamics are effectively captured by a two-dimensional dilaton theory of gravity. By employing a wiggling boundary ansatz we compute a deformed Schwarzian action and use this boundary action to compute a logarithmic correction to the entropy of the Lifshitz-like black hole,

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