Fermions in the Ashtekar-Barbero connection formalism for arbitrary values of the Immirzi parameter
- Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale Aldo Moro 5, I-00185, Rome (Italy)
The Ashtekar-Barbero-Immirzi formulation of general relativity is extended to include spinor matter fields. Our formulation applies to generic values of the Immirzi parameter and reduces to the Ashtekar-Romano-Tate approach when the Immirzi parameter is taken equal to the imaginary unit. The dynamics of the gravity-fermions coupled system is described by the Holst plus Dirac action with a nonminimal coupling term. The nonminimal interaction together with the Holst modification to the Hilbert-Palatini action reconstruct the Nieh-Yan invariant, so that the effective action coming out is the one of Einstein-Cartan theory with a typical Fermi-like interaction term: in spite of the presence of spinor matter fields, the Immirzi parameter plays no role in the classical effective dynamics and results to be only a multiplicative factor in front of a total divergence. We reduce the total action of the theory to the sum of dynamically independent Ashtekar-Romano-Tate actions for self and anti-self-dual connections, with different weights depending on the Immirzi parameter. This allows to calculate the constraints of the complete theory in a simple way, it is only necessary to realize that the Barbero-Immirzi connection is a weighted sum of the self and anti-self-dual Ashtekar connections. Finally the obtained constraints for the separated action result to be polynomial in terms of the self and anti-self-dual connections, this could have implications in the inclusion of spinor matter in the framework of nonperturbative quantum gravity.
- OSTI ID:
- 20782915
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 73, Issue 8; Other Information: DOI: 10.1103/PhysRevD.73.084016; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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