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| Ultimo aggiornamento | 10 lug 2013 |
| Autore |
Cercare il tesista cliccando sul pulsante a sinistra !
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| Sesso | |
| Esperimento | PD51 |
| Tipo | Laurea Magistrale |
| Destinazione dopo il cons. del titolo | Altro |
| Università | Università Di Ferrara |
| Strutt.INFN/Ente |
Ferrara |
| Titolo | Massive Gravity in Hamiltonian formalism |
| Abstract | A possibility to find a consistent Lorentz-invariant theory of Massive Gravity is given by the Vainshtein mechanism, by which the vDVZ discontinuity can be solved with the aid of the Boulware-Deser ghost mode: this mechanism involves a new length scale, the Vainshtein radius, below which non-linear contributions become important and may cure the discontinuity. In the first chapter we make an overview of regular and singular systems, first in Lagrangian and then in Hamiltonian formalism. Also the relation between constraints and gauge transformations with the classification between first and second class constraints are described. In the second chapter, after a short introduction on General Relativity, we introduce the ADM formalism, useful to derive the Hamiltonian associated to the Einstein-Hilbert action. Then we will focus on the linearized version of General Relativity and discuss the number of degrees of freedom that propagate in the theory through the classification of the constraints. The third chapter is devoted to the Fierz-Pauli model: by the introduction of an additional Lorentz-invariant mass term to the linearized version of the Einstein- Hilbert Lagrangian we enlarge the dimension of the phase-space necessary to de- scribe the physical system. We will see that the Fierz-Pauli tuning is a necessary condition to have a free-ghosts theory at linearized level around a Minkowsky background. Problems related to Lorentz-invariant Massive Gravity, such the vDVZ dis- continuity, are presented in the fourth chapter. At the end of this chapter we introduce the Vainshtein screening mechanism, focusing on the possibility that non linear contributions may restore light bending predictions given by General Relativity. In the fifth chapter a generic Lorentz-violating mass term is added to the linearized Einstein-Hilbert Lagrangian. Some particular cases, free of pathologies typical of Lorentz-invariant Massive Gravity, are presented: allowing a Lorentz breaking mass term indeed leads, for some particular choice of the parameters, to a free-ghost theory, to the absence of the vDVZ discontinuity and to an higher value of the strong coupling scale with respect to Lorentz-invariant massive theories. |
| Anno iscrizione | |
| Data conseguimento | 21 mar 2013 |
| Luogo conseguimento | Via Savonarola 9 presso la Sala Lauree del Rettorato |
| Relatore/i |
Denis Comelli |
| File PDF |
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| File PS | |
