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Dima, Alexandru (2017) Nonlinear aspects of the effective theory of dark energy. [Magistrali biennali]

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Abstract

The goal of this project is to study the effects predicted by scalar-tensor theories of dark energy on small scales. Scalar-tensor theories has been introduced to modify gravity in the infrared. However, large scale modifications of gravity are necessarily associated to short-scale ones. In order to be in accordance with current observational tests on small scales, one can introduce a screening mechanism that is effective in environments where nonlinearities of the scalar field become important, suppressing the extra degrees of freedom. The Vainshtein screening has been already proven to work in many scalar-tensor theories, in particular in the most general second-order covariant theory for gravity coupled to a scalar degree of freedom, the so-called Horndeski theory. The focus of this thesis is on the breaking of this mechanism in the extensions of Horndeski: we retrieve the failure of the screening for beyond Horndeski theories, starting from more general premises. Finally, we tackle the challenge of generalizing this result further to DHOST theories.

Item Type:Magistrali biennali
Corsi di Diploma di Laurea:Scuola di Scienze > Fisica
Uncontrolled Keywords:Dark Energy, Scalar-tensor theories, Effective theory, Horndeski, DHOST, Vainshtein screening
Subjects:Area 02 - Scienze fisiche > FIS/02 Fisica teorica, modelli e metodi matematici
Area 02 - Scienze fisiche > FIS/05 Astronomia e astrofisica
Codice ID:56992
Relatore:Matarrese, Sabino and Vernizzi, Filippo
Data della tesi:September 2017
Biblioteca:Polo di Scienze > Dip. Fisica e Astronomia "Galileo Galilei" - Biblioteca
Tipo di fruizione per il documento:on-line per i full-text
Tesi sperimentale (Si) o compilativa (No)?:No

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