Minimal Massive 3D Gravity
  We present an alternative to Topologically Massive Gravity (TMG) with the same "minimal" bulk properties; i.e. a single local degree of freedom that is realized as a massive graviton in linearization about an anti-de Sitter (AdS) vacuum. However, in contrast to TMG, the new "minimal massive gravity" has both a positive energy graviton and positive central charges for the asymptotic AdS-boundary conformal algebra. 
Eric Bergshoeff, Olaf Hohm, Wout Merbis, Alasdair J. Routh and Paul K.   Townsend
hep-th gr-qc