59 research outputs found
Effective action in a higher-spin background
We consider a free massless scalar field coupled to an infinite tower of
background higher-spin gauge fields via minimal coupling to the traceless
conserved currents. The set of Abelian gauge transformations is deformed to the
non-Abelian group of unitary operators acting on the scalar field. The gauge
invariant effective action is computed perturbatively in the external fields.
The structure of the various (divergent or finite) terms is determined. In
particular, the quadratic part of the logarithmically divergent (or of the
finite) term is expressed in terms of curvatures and related to conformal
higher-spin gravity. The generalized higher-spin Weyl anomalies are also
determined. The relation with the theory of interacting higher-spin gauge
fields on anti de Sitter spacetime via the holographic correspondence is
discussed.Comment: 40 pages, Some errors and typos corrected, Version published in JHE
A HIERARCHY OF GAUGED GRASSMANIAN MODELS IN DIMENSIONS WITH SELF-DUAL INSTANTONS
We present a hierarchy of gauged Grassmanian models in dimensions, where
the gauge field takes its values in the chiral
representation of SO(4p). The actions of all these models are absolutely
minimised by a hierarchy of self-duality equations, all of which reduce to a
single pair of coupled ordinary differential equations when subjected to
dimensional spherical symmetry.Comment: latex file, 13 page
Spin 3 cubic vertices in a frame-like formalism
Till now most of the results on interaction vertices for massless higher spin
fields were obtained in a metric-like formalism using completely symmetric
(spin-)tensors. In this, the Lagrangians turn out to be very complicated and
the main reason is that the higher the spin one want to consider the more
derivatives one has to introduce. In this paper we show that such
investigations can be greatly simplified if one works in a frame-like
formalism. As an illustration we consider massless spin 3 particle and
reconstruct a number of vertices describing its interactions with lower spin 2,
1 and 0 ones. In all cases considered we give explicit expressions for the
Lagrangians and gauge transformations and check that the algebra of gauge
transformations is indeed closed.Comment: 17 pades, no figure
Higher spin interactions with scalar matter on constant curvature spacetimes: conserved current and cubic coupling generating functions
Cubic couplings between a complex scalar field and a tower of symmetric
tensor gauge fields of all ranks are investigated on any constant curvature
spacetime of dimension d>2. Following Noether's method, the gauge fields
interact with the scalar field via minimal coupling to the conserved currents.
A symmetric conserved current, bilinear in the scalar field and containing up
to r derivatives, is obtained for any rank r from its flat spacetime
counterpart in dimension d+1, via a radial dimensional reduction valid
precisely for the mass-square domain of unitarity in (anti) de Sitter spacetime
of dimension d. The infinite collection of conserved currents and cubic
vertices are summarized in a compact form by making use of generating functions
and of the Weyl/Wigner quantization on constant curvature spaces.Comment: 35+1 pages, v2: two references added, typos corrected, enlarged
discussions in Subsection 5.2 and in Conclusion, to appear in JHE
Higher-Spin Fermionic Gauge Fields and Their Electromagnetic Coupling
We study the electromagnetic coupling of massless higher-spin fermions in
flat space. Under the assumptions of locality and Poincare invariance, we
employ the BRST-BV cohomological methods to construct consistent
parity-preserving off-shell cubic 1-s-s vertices. Consistency and
non-triviality of the deformations not only rule out minimal coupling, but also
restrict the possible number of derivatives. Our findings are in complete
agreement with, but derived in a manner independent from, the
light-cone-formulation results of Metsaev and the string-theory-inspired
results of Sagnotti-Taronna. We prove that any gauge-algebra-preserving vertex
cannot deform the gauge transformations. We also show that in a local theory,
without additional dynamical higher-spin gauge fields, the non-abelian vertices
are eliminated by the lack of consistent second-order deformations.Comment: 44 pages; references added, minor changes made, to appear in JHE
Maxwell-like Lagrangians for higher spins
We show how implementing invariance under divergence-free gauge
transformations leads to a remarkably simple Lagrangian description of massless
bosons of any spin. Our construction covers both flat and (A)dS backgrounds and
extends to tensors of arbitrary mixed-symmetry type. Irreducible and traceless
fields produce single-particle actions, while whenever trace constraints can be
dispensed with the resulting Lagrangians display the same reducible,
multi-particle spectra as those emerging from the tensionless limit of free
open-string field theory. For all explored options the corresponding kinetic
operators take essentially the same form as in the spin-one, Maxwell case.Comment: 77 pages, revised version. Erroneous interpretation and proof of the
gauge-fixing procedure for mixed-symmetry fields corrected. As a consequence,
the mixed-symmetry, one-particle Lagrangians are to be complemented with
conditions on the divergences of the fields; all other conclusions unchanged.
Additional minor changes including references added. To appear in JHE
Higher-Spin Interactions: four-point functions and beyond
In this work we construct an infinite class of four-point functions for
massless higher-spin fields in flat space that are consistent with the gauge
symmetry. In the Lagrangian picture, these reflect themselves in a peculiar
non-local nature of the corresponding non-abelian higher-spin couplings implied
by the Noether procedure that starts from the fourth order. We also comment on
the nature of the colored spin-2 excitation present both in the open string
spectrum and in the Vasiliev system, highlighting how some aspects of String
Theory appear to reflect key properties of Field Theory that go beyond its low
energy limit. A generalization of these results to n-point functions, fermions
and mixed-symmetry fields is also addressed.Comment: 66 pages, 10 figures, 1 table, LaTex. Several statements clarified.
Final version to appear in JHE
Asymptotic W-symmetries in three-dimensional higher-spin gauge theories
We discuss how to systematically compute the asymptotic symmetry algebras of
generic three-dimensional bosonic higher-spin gauge theories in backgrounds
that are asymptotically AdS. We apply these techniques to a one-parameter
family of higher-spin gauge theories that can be considered as large N limits
of SL(N) x SL(N) Chern-Simons theories, and we provide a closed formula for the
structure constants of the resulting infinite-dimensional non-linear
W-algebras. Along the way we provide a closed formula for the structure
constants of all classical W_N algebras. In both examples the higher-spin
generators of the W-algebras are Virasoro primaries. We eventually discuss how
to relate our basis to a non-primary quadratic basis that was previously
discussed in literature.Comment: 61 page
Half-integer Higher Spin Fields in (A)dS from Spinning Particle Models
We make use of O(2r+1) spinning particle models to construct linearized
higher-spin curvatures in (A)dS spaces for fields of arbitrary half-integer
spin propagating in a space of arbitrary (even) dimension: the field
potentials, whose curvatures are computed with the present models, are
spinor-tensors of mixed symmetry corresponding to Young tableaux with D/2 - 1
rows and r columns, thus reducing to totally symmetric spinor-tensors in four
dimensions. The paper generalizes similar results obtained in the context of
integer spins in (A)dS.Comment: 1+18 pages; minor changes in the notation, references updated.
Published versio
A Note on Vectorial AdS/CFT Duality for Spin- Boundary Theory
The vectorial holographic correspondences between higher-spin theories in
AdS and free vector models on the boundary are extended to the cases where
the latter is described by free massless spin- field. The dual higher-spin
theory in the bulk does not include gravity and can only be defined on rigid
AdS background with boundary. We discuss various properties of these
rather special higher-spin theories and calculate their one-loop free energies.
We show that the result is proportional to the same quantity for spin-
doubleton treated as if it is a AdS field. Finally, we consider even more
special case where the boundary theory itself is given by an infinite tower of
massless higher-spin fields.Comment: 27 pages, version to appear in JHE
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