2,487 research outputs found
Strong obstruction of the Berends-Burgers-van Dam spin-3 vertex
In the eighties, Berends, Burgers and van Dam (BBvD) found a nonabelian cubic
vertex for self-interacting massless fields of spin three in flat spacetime.
However, they also found that this deformation is inconsistent at higher order
for any multiplet of spin-three fields. For arbitrary symmetric gauge fields,
we severely constrain the possible nonabelian deformations of the gauge algebra
and, using these results, prove that the BBvD obstruction cannot be cured by
any means, even by introducing fields of spin higher (or lower) than three.Comment: 19 pages, no figur
Higher Spin Interactions in Four Dimensions: Vasiliev vs. Fronsdal
We consider four-dimensional Higher-Spin Theory at the first nontrivial order
corresponding to the cubic action. All Higher-Spin interaction vertices are
explicitly obtained from Vasiliev's equations. In particular, we obtain the
vertices that are not determined solely by the Higher-Spin algebra structure
constants. The dictionary between the Fronsdal fields and Higher-Spin
connections is found and the corrections to the Fronsdal equations are derived.
These corrections turn out to involve derivatives of arbitrary order. We
observe that the vertices not determined by the Higher-Spin algebra produce
naked infinities, when decomposed into the minimal derivative vertices and
improvements. Therefore, standard methods can only be used to check a rather
limited number of correlation functions within the HS AdS/CFT duality. A
possible resolution of the puzzle is discussed.Comment: 56 pages=40+Appendices; 1 figure; typos fixed, one ref adde
On the uniqueness of higher-spin symmetries in AdS and CFT
We study the uniqueness of higher-spin algebras which are at the core of
higher-spin theories in AdS and of CFTs with exact higher-spin symmetry, i.e.
conserved tensors of rank greater than two. The Jacobi identity for the gauge
algebra is the simplest consistency test that appears at the quartic order for
a gauge theory. Similarly, the algebra of charges in a CFT must also obey the
Jacobi identity. These algebras are essentially the same. Solving the Jacobi
identity under some simplifying assumptions spelled out, we obtain that the
Eastwood-Vasiliev algebra is the unique solution for d=4 and d>6. In 5d there
is a one-parameter family of algebras that was known before. In particular, we
show that the introduction of a single higher-spin gauge field/current
automatically requires the infinite tower of higher-spin gauge fields/currents.
The result implies that from all the admissible non-Abelian cubic vertices in
AdS(d), that have been recently classified for totally symmetric higher-spin
gauge fields, only one vertex can pass the Jacobi consistency test. This cubic
vertex is associated with a gauge deformation that is the germ of the
Eastwood-Vasiliev's higher-spin algebra.Comment: 37 pages; refs added, proof of uniquiness was improve
Two-way time transfers between NRC/NBS and NRC/USNO via the Hermes (CTS) satellite
At each station the differences were measured between the local UTC seconds pulse and the remote UTC pulse received by satellite. The difference between the readings, if station delays are assumed to be symmetrical, is two times the difference between the clocks at the two ground station sites. Over a 20-minute period, the precision over the satellite is better than 1 ns. The time transfer from NRC to the CRC satellite terminal near Ottawa and from NBS to the Denver HEW terminal was examined
Self-Protection of Massive Cosmological Gravitons
Relevant deformations of gravity present an exciting window of opportunity to
probe the rigidity of gravity on cosmological scales. For a single-graviton
theory, the leading relevant deformation constitutes a graviton mass term. In
this paper, we investigate the classical and quantum stability of massive
cosmological gravitons on generic Friedman backgrounds. For a Universe
expanding towards a de Sitter epoch, we find that massive cosmological
gravitons are self-protected against unitarity violations by a strong coupling
phenomenon.Comment: 1+11 pages, v2: references adde
Relative Effectiveness of Repellents for Preventing Deer Damage to Japanese Yews
Homeowners whose landscape plants are repeatedly browsed by white-tailed deer (Odocoileus virginianus) are interested in repellent products that are effective and long-lasting. New products come to market with limited experimental testing. We conducted a 10-week trial from Feb. through Apr. 1999 to test the duration and efficacy of six commercial deer repellents [Deer-Away Big Game Repellent (BGR) mix, BGR spray, Deer-Off, Deer Stopper II, Repellex, Tree Guard] and two experimental deer repellents (CU-A and CU-B) relative to each other and to untreated plants. Treated and control balled japanese yew (Taxus cuspidata) shrubs were placed at each of 10 homeowner sites with known white-tailed deer damage near Ithaca, NY. Yews are frequently eaten by deer during winter and provide a good bioassay for testing repellents, especially during the winter months. We checked shrubs once weekly and took photographs of damaged yews to measure the amount of deer browsing. We calculated the surface area of shrubs in each photograph by using digital analysis software. To determine significant differences over time, we applied statistical analysis using analysis of variance. Deer repellents that provided the most consistent protection were BGR spray, BGR mix, Deer-Off, and Deer Stopper II. The japanese pachysandra (Pachysandra terminalis) extracts in experimental repellents CU-A and CU-B were not effective. The performance of other commercial repellents varied considerably among sites, and these products were unreliable
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