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A simple parity violating gravity model without ghost instability

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arxiv 2007.08038 v3 pith:UBC22K3Y submitted 2020-07-15 gr-qc astro-ph.COhep-th

A simple parity violating gravity model without ghost instability

classification gr-qc astro-ph.COhep-th
keywords modelgravityparityviolatingcoupledderivativesdynamicalfield
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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In this paper we consider a parity violating gravity model without higher derivatives, thus ghost free. This model is constructed from the tetrad and its derivatives and coupled to a dynamical scalar field, like axion. It can be reduced from the Nieh-Yan term within the framework of teleparallel gravity. We apply this model to cosmology and investigate its consequences on cosmological perturbation theory. We find that the coupled dynamical scalar field lost its independent dynamics at the linear order and the parity violating term itself behaves like a viscosity. For gravitational waves, this model produces velocity difference between left- and right-handed polarizations, but generates no amplitude discrepancy.

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Cited by 9 Pith papers

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