Some simple theories of gravity with propagating torsion

Abstract

We consider antisymmetric Metric-Affine Theories of Gravity with a Lagrangian containing the most general terms up to dimension four and search for theories that are ghost- and tachyon-free when expanded around flat space. We find new examples that propagate only the graviton and one other massive degree of freedom of spin zero, one or two. These models require terms of the form $(\nabla T{)}^2$ in the Lagrangian, that have been largely ignored in the literature.

22 pages, v3: references are corrected

References in corpus (6)

• Unitarity, stability and loops of unstable ghosts
• Solution to the ghost problem in fourth order derivative theories
• A New Class of Ghost and Tachyon Free Metric Affine Gravities
• Metric-Affine Gravity as an Effective Field Theory
• Radiatively stable ghost and tachyon freedom in Metric Affine Gravity
• Ghost and Tachyon Free Propagation up to spin-3 in Lorentz Invariant Field Theories

Cited by in corpus (1)

• Revisiting Stability in New General Relativity