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S. Deser

Publications and source records attributed to S. Deser.

At least 127 records · Page 7Linked to original sources
arXiv2000

Closed Form Effective Conformal Anomaly Actions in D$\geq$4

I present, in any D$\geq$4, closed-form type B conformal anomaly effective actions incorporating the logarithmic scaling cutoff dependence that generates these anomalies. Their construction is based on a novel class of Weyl-invariant tensor operators. The only known type A actions in D$\geq$4 are extensions of the Polyakov integral in D=2; despite contrary appearances, we show that their nonlocality does not conflict with general anomaly requirements. They are, however, physically unsatisfactory, prompting a brief attempt at better versions.

hep-th↗
arXiv1999

Infinities in Quantum Gravities

We first present a review, intended for classical relativists, of the ultraviolet difficulties faced by local quantum gravity theories in both the usual Einstein versions and in their supergravity extensions, at least perturbatively. These problems, present in arbitrary dimensions, are traceable to the dimensionality of the Einstein constant. We then summarize very recent results about supergravity at the highest allowed dimension, D=11, showing that also this unique model suffers from infinities already at 2 loops, despite its high degree of supersymmetry. The conclusion is that there is no viable nonghost quantum field model that includes general relativity.

gr-qc↗
arXiv1999

Two Outcomes for Two Old (Super-)Problems

I briefly review the outcomes of two very different old questions -- where global SUSY improves on ordinary QFT -- when they are in turn posed in the local, SUGRA, context. The first concerns the unexpectedly powerful role of the "Dirac square root" graded algebra relation $E=Q^2$, originally found in D=4 SUSY by Gol'fand and Likhtman, in proving positive energy theorems both in SUGRA and in ordinary gravity theories, where $E$ and $Q$ have very different -- gauge generator -- definitions. The second seeks SUGRA counterparts of the boson/fermion loop ultraviolet cancellations in SUSY models. Here the result is negative: local supersymmetry cannot overcome the infinities associated with the dimensional gravitational $κ^2$ even, as recently shown, in maximal D=11 SUGRA.

hep-th↗
arXiv1999

Graviton-Graviton Scattering, Bel-Robinson and Energy (Pseudo)-Tensors

Motivated by recent work involving the graviton-graviton tree scattering amplitude, and its twin descriptions as the square of the Bel-Robinson tensor, $B_{\m\n\a\b}$, and as the "current-current interaction" square of gravitational energy pseudo-tensors $t_{\a\b}$,we find an exact tensor-square root equality $B_{\mn\a\b} = \pa^2_\mn t_{\a\b}$, for a combination of Einstein and Landau-Lifschitz $t_\ab$, in Riemann normal coordinates. In the process, we relate, on-shell, the usual superpotential basis for classifying pseudo-tensors with one spanned by polynomials in the curvature.

gr-qc↗
arXiv1999

Higher Derivative Chern--Simons Extensions

We study the higher-derivative extensions of the D=3 Abelian Chern--Simons topological invariant that would appear in a perturbative effective action's momentum expansion. The leading, third-derivative, extension I_ECS turns out to be unique. It remains parity-odd but depends only on the field strength, hence no longer carries large gauge information, nor is it topological because metric dependence accompanies the additional covariant derivatives, whose positions are seen to be fixed by gauge invariance. Viewed as an independent action, I_ECS requires the field strength to obey the wave equation. The more interesting model, adjoining I_ECS to the Maxwell action, describes a pair of excitations. One is massless, the other a massive ghost, as we exhibit both via the propagator and by performing the Hamiltonian decomposition. We also present this model's total stress tensor and energy. Other actions involving I_ECS are also noted.

hep-th↗
arXiv1999

The Immortal Bel-Robinson Tensor

We present some generalizations, and novel properties, of the Bel-Robinson tensor, in the context of constructing local invariants in D=11 supergravity.

gr-qc↗
arXiv1998

Counterterms/M-theory Corrections to D=11 Supergravity

We construct a local on-shell invariant in D=11 supergravity from the nonlocal four-point tree scattering amplitude.Its existence, together with earlier arguments, implies non-renormalizability of the theory at lowest possible, two loop, level. This invariant, whose leading bosonic terms are exhibited, may also express the leading, "zero-slope", M$-$theory corrections to its D=11 supergravity limit.

hep-th↗
arXiv1998

Dimensionally Challenged Gravities

I review some ways in which spacetime dimensionality enters explicitly in gravitation. In particular, I recall some unusual geometrical gravity models that are constructible in dimensions different from four, especially in D=3 where even ordinary Einstein theory is "different", e.g., fully Machian.

gr-qc↗
arXiv1998

``Good Propagation'' Constraints on Dual Invariant Actions in Electrodynamics and on Massless Fields

We present some consequences of non-anomalous propagation requirements on various massless fields. Among the models of nonlinear electrodynamics we show that only Maxwell and Born-Infeld also obey duality invariance. Separately we show that, for actions depending only on the $F_\mn^2$ invariant, the permitted models have $L \sim \sqrt{1 + F^2}$. We also characterize acceptable vector-scalar systems. Finally we find that wide classes of gravity models share with Einstein the null nature of their characteristic surfaces.

hep-th↗
arXiv1998

Mapping Hawking into Unruh Thermal Properties

By globally embedding curved spaces into higher dimensional flat ones, we show that Hawking thermal properties map into their Unruh equivalents: The relevant curved space detectors become Rindler ones, whose temperature and entropy reproduce the originals. Specific illustrations include Schwarzschild, Schwarzschild-(anti)deSitter, Reissner-Nordstrom and BTZ spaces.

hep-th↗
arXiv1998

Equivalence of Hawking and Unruh Temperatures and Entropies Through Flat Space Embeddings

We present a unified description of temperature and entropy in spaces with either "true" or "accelerated observer" horizons: In their (higher dimensional) global embedding Minkowski geometries, the relevant detectors have constant accelerations a_{G}; associated with their Rindler horizons are temperature a_{G}/2πand entropy equal to 1/4 the horizon area. Both quantities agree with those calculated in the original curved spaces. As one example of this equivalence, we obtain the temperature and entropy of Schwarzschild geometry from its flat D=6 embedding.

hep-th↗
arXiv1998

D=11 Supergravity Revisited

I discuss two novel results in D=11 Supergravity. The first establishes, in two complementary ways, a no-go theorem that, in contrast to all D<11, a cosmological extension of the theory does not exist. The second deals with the structure of (on-shell) four-point invariants. These are important both for establishing existence of the lowest (2-loop) order candidate counter-terms in the theory proper, as well as for comparison with the form of eventual "zero-slope" QFT limit of M-theory.

hep-th↗
arXiv1998

p-brane Dyons, theta-terms and Dimensional Reduction

We present two novel derivations of the recently established $(-)^p$ factor in the charge quantization condition for $p$-brane dyon sources in spacetime dimension $D$=$2p$+2. The first requires consistency of the condition under the charge shifts produced by (generalized) $θ$-terms. The second traces the sign difference between adjoining dimensions to compactification effects.

hep-th↗
arXiv1998

Born-Infeld-Einstein Actions?

We present some obvious physical requirements on gravitational avatars of non-linear electrodynamics and illustrate them with explicit determinantal Born-Infeld-Einstein models. A related procedure, using compensating Weyl scalars, permits us to formulate conformally invariant versions of these systems as well.

hep-th↗