Novel Properties of Massive Higher Spin Fields

I outline a series of results obtained in collaboration with A. Waldron on the properties of massive higher (s>1) spin fields in cosmological, constant curvature, backgrounds and the resulting unexpected qualitative effects on their degrees of freedom and unitarity properties. The dimensional parameter \L extends the flat space m-line to a (m^2,\L) "phase" plane in which these novel phenomena unfold. In this light, I discuss a possible partial resurrection of deSitter supergravity. I will also exhibit the well-known causality problems of coupling these systems to gravity and, for complex fields, to electromagnetism, systematizing some of the occasionally misunderstood obstacles to interactions, particularly for s = 3/2 and 2.Comment: 9 pages, 1 figure. Invited talk at "Renormalization Group and Anomalies in Gravity and Cosmology", Ouro Preto, Brazil, March 17-23, 200

Energy in Topologically Massive Gravity

We define conserved gravitational charges in -cosmologically extended- topologically massive gravity, exhibit them in surface integral form about their de-Sitter or flat vacua and verify their correctness in terms of two basic types of solution.Comment: 6 page

No Bel-Robinson Tensor for Quadratic Curvature Theories

We attempt to generalize the familiar covariantly conserved Bel-Robinson tensor B_{mnab} ~ R R of GR and its recent topologically massive third derivative order counterpart B ~ RDR, to quadratic curvature actions. Two very different models of current interest are examined: fourth order D=3 "new massive", and second order D>4 Lanczos-Lovelock, gravity. On dimensional grounds, the candidates here become B ~ DRDR+RRR. For the D=3 model, there indeed exist conserved B ~ dRdR in the linearized limit. However, despite a plethora of available cubic terms, B cannot be extended to the full theory. The D>4 models are not even linearizable about flat space, since their field equations are quadratic in curvature; they also have no viable B, a fact that persists even if one includes cosmological or Einstein terms to allow linearization about the resulting dS vacua. These results are an unexpected, if hardly unique, example of linearization instability.Comment: published versio

Birkhoff for Lovelock Redux

We show succinctly that all metric theories with second order field equations obey Birkhoff's theorem: their spherically symmetric solutions are static.Comment: Submitted to CQ

Stability of Massive Cosmological Gravitons

We analyze the physics of massive spin 2 fields in (A)dS backgrounds and exhibit that: The theory is stable only for masses m^2 >= 2\Lambda/3, where the conserved energy associated with the background timelike Killing vector is positive, while the instability for m^2<2\Lambda/3 is traceable to the helicity 0 energy. The stable, unitary, partially massless theory at m^2=2\Lambda/3 describes 4 propagating degrees of freedom, corresponding to helicities (+/-2,+/-1) but contains no 0 helicity excitation.Comment: 13 pages, LaTeX, version to appear in Phys. Lett.

Dual descriptions of spin two massive particles in D=2+1D=2+1 via master actions

In the first part of this work we show the decoupling (up to contact terms) of redundant degrees of freedom which appear in the covariant description of spin two massive particles in $D=2+1$. We make use of a master action which interpolates, without solving any constraints, between a first, second and third order (in derivatives) self-dual model. An explicit dual map between those models is derived. In our approach the absence of ghosts in the third order self-dual model, which corresponds to a quadratic truncation of topologically massive gravity, is due to the triviality (no particle content) of the Einstein-Hilbert action in $D=2+1$. In the second part of the work, also in $D=2+1$, we prove the quantum equivalence of the gauge invariant sector of a couple of self-dual models of opposite helicities (+2 and -2) and masses $m_+$ and $m_-$ to a generalized self-dual model which contains a quadratic Einstein-Hilbert action, a Chern-Simons term of first order and a Fierz-Pauli mass term. The use of a first order Chern-Simons term instead of a third order one avoids conflicts with the sign of the Einstein-Hilbert action.Comment: title and abstract slightly modified, 3 references added, comments on interactions include

First-order Formalism and Odd-derivative Actions

In this pedagogical note, we discuss obstacles to the usual Palatini formulations of gauge and gravity theories in presence of odd-derivative order, Chern-Simons, terms.Comment: 4 pages. Dedicated to Rafael Sorkin on his 60th Birthda

A note on matter covariantization for gravity coupling

Covariantization is of course required for initially flat space matter to couple consistently to GR; here I show in detail for concrete systems how it follows in the same physical way as that deriving GR itself from its initial free-field form.Comment: Published version, typos correcte