Unitarity problems in 3D gravity theories


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Alkac G., Basanisi L., KILIÇARSLAN E., TEKİN B.

Physical Review D, cilt.96, sa.2, 2017 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 96 Sayı: 2
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1103/physrevd.96.024010
  • Dergi Adı: Physical Review D
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Uşak Üniversitesi Adresli: Evet

Özet

We revisit the problem of the bulk-boundary unitarity clash in 2+1-dimensional gravity theories, which has been an obstacle in providing a viable dual two-dimensional conformal field theory for bulk gravity in anti-de Sitter (AdS) spacetime. Chiral gravity, which is a particular limit of cosmological topologically massive gravity (TMG), suffers from perturbative log-modes with negative energies inducing a nonunitary logarithmic boundary field theory. We show here that any f(R) extension of TMG does not improve the situation. We also study the perturbative modes in the metric formulation of minimal massive gravity - originally constructed in a first-order formulation - and find that the massive mode has again negative energy except in the chiral limit. We comment on this issue and also discuss a possible solution to the problem of negative-energy modes. In any of these theories, the infinitesimal dangerous deformations might not be integrable to full solutions; this suggests a linearization instability of AdS spacetime in the direction of the perturbative log-modes.