How unimodular gravity theories differ from general relativity at quantum level

Autor(es)

Bufalo, R. ^{[1, 2]} ; Oksanen, M. ^[2] ; Tureanu, A. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista, Inst Fis Teor, BR-01140070 Sao Paulo, SP - Brazil

^[2] Univ Helsinki, Dept Phys, FIN-00014 Helsinki - Finland

• Tipo de documento: Artigo Científico
• Fonte: EUROPEAN PHYSICAL JOURNAL C; v. 75, n. 10 OCT 6 2015.
• Citações Web of Science: 18

Resumo

We investigate path integral quantization of two versions of unimodular gravity. First a fully diffeomorphism-invariant theory is analyzed, which does not include a unimodular condition on the metric, while still being equivalent to other unimodular gravity theories at the classical level. The path integral has the same form as in general relativity (GR), except that the cosmological constant is an unspecified value of a variable, and it thus is unrelated to any coupling constant. When the state of the universe is a superposition of vacuum states, the path integral is extended to include an integral over the cosmological constant. Second, we analyze the standard unimodular theory of gravity, where the metric determinant is fixed by a constraint. Its path integral differs from the one of GR in two ways: the metric of spacetime satisfies the unimodular condition only in average over space, and both the Hamiltonian constraint and the associated gauge condition have zero average over space. Finally, the canonical relation between the given unimodular theories of gravity is established. (AU)

• Processo FAPESP: 13/26571-4 - Uma análise Hamiltoniana de teorias de gravitação modificadas
• Beneficiário: Rodrigo Santos Bufalo
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado