Thesis

Characteristic formulations of general relativity and applications

• Call:

  IDPASC Portugal - PHD Programme 2017

• Academic Year:

  2017 / 2018

• Domain:

  General Relativity

• Supervisor:

  Miguel Zilhao

• Co-Supervisor:

  David Hilditch

• Institution:

  Instituto Superior Técnico

• Host Institution:

  Instituto Superior Técnico

• Abstract:

  In the early universe there were processes that may have generated detectable signatures in the gravitational wave spectrum. These processes include inflation, topological defects, and first order phase transitions. The Laser Interferometer Space Antenna (LISA), the proposed space-based interferometer mission scheduled to launch in 2030 [1], may have the right frequency response to detect the imprint of some of these processes, such as first order phase transitions at the electroweak scale and above. It is known that in the Standard Model of particle physics this transition is a cross-over (which does not generate a gravitational wave signal); however, in theories beyond the Standard Model, a first order phase transition is indeed possible [2,3,4], leading to the exciting possibility of exploring particle physics with gravitational waves. To date, the modelling of these signatures has been done through very computationally expensive lattice simulations [5]. An alternative approach, which has so far not been attempted, would be to model holographically such systems with phase transitions, through the gauge/gravity duality. Using holography, one can straightforwardly evolve a gauge theory with a thermal phase transition by evolving Einstein's equations [6,7], drastically reducing the computational requirements. The goal of this project is then to find the best way to model holographically such systems with first order phase transitions, explore its thermodynamical properties, numerically evolve Einstein's equations through phase transitions, and compute the corresponding signature in the gravitational wave spectrum. [1] https://www.lisamission.org/proposal/LISA.pdf [2] https://arxiv.org/abs/hep-ph/9603420 [3] https://arxiv.org/abs/hep-ph/9604440 [4] https://arxiv.org/abs/hep-ph/0003122 [5] https://arxiv.org/abs/1304.2433 [6] https://arxiv.org/abs/1703.02948 [7] https://arxiv.org/abs/1704.05387