Torsional instanton effects in quantum gravity
arXiv:1411.4793 · doi:10.1103/PhysRevD.90.124081
Abstract
We show that, in the first order gravity theory coupled to axions, the instanton number of the Giddings-Strominger wormhole can be interpreted as the Nieh-Yan topological index. The axion charge of the baby universes is quantized in terms of the Nieh-Yan integers. Tunneling between universes of different Nieh-Yan charges implies a nonperturbative vacuum state. The associated topological vacuum angle can be identified with the Barbero-Immirzi parameter.
Published version
References in corpus (14)
- Real Ashtekar Variables for Lorentzian Signature Space-times
- Real and complex connections for canonical gravity
- Topological Invariants, Instantons and Chiral Anomaly on Spaces with Torsion
- Beyond Einstein-Cartan gravity: Quadratic torsion and curvature invariants with even and odd parity including all boundary terms
- Topological Interpretation of Barbero-Immirzi Parameter
- 4d Lorentzian Holst action with topological terms
- Yang-Mills analogues of the Immirzi ambiguity
- Torsion and the Gravity Dual of Parity Symmetry Breaking in AdS4/CFT3 Holography
- Topological parameters in gravity
- The Immirzi Parameter as an Instanton Angle
- Gravity Asymptotics with Topological Parameters
- Quantum realizations of Hilbert-Palatini second-class constraints
- SU(2) gauge theory of gravity with topological invariants
- Vacuum tunneling in gravity