2,508 research outputs found
Gravitational cubic interactions for a massive mixed symmetry gauge field
In a recent paper arXiv:1107.1872 cubic gravitational interactions for a
massless mixed symmetry field in AdS space have been constructed. In the
current paper we extend these results to the case of massive field. We work in
a Fradkin-Vasiliev approach and use frame-like gauge invariant description for
massive field which works in (A)dS spaces with arbitrary values of cosmological
constant including flat Minkowski space. In this, massless limit in AdS space
coincides with the results of arXiv:1107.1872 while we show that it is
impossible to switch on gravitational interaction for massless field in dS
space.Comment: 13 page
Oxygen in dense interstellar gas - the oxygen abundance of the star forming core rho Oph A
Oxygen is the third most abundant element in the universe, but its chemistry
in the interstellar medium is still not well understood. In order to critically
examine the entire oxygen budget, we attempt here initially to estimate the
abundance of atomic oxygen, O, in the only one region, where molecular oxygen,
O2, has been detected to date. We analyse ISOCAM-CVF spectral image data toward
rho Oph A to derive the temperatures and column densities of H2 at the
locations of ISO-LWS observations of two [OI] 3P_J lines. The intensity ratios
of the (J=1-2) 63um to (J=0-1) 145um lines largely exceed ten, attesting to the
fact that these lines are optically thin. This is confirmed by radiative
transfer calculations, making these lines suitable for abundance
determinations. For that purpose, we calculate line strengths and compare them
to the LWS observations. Excess [OI] emission is observed to be associated with
the molecular outflow from VLA 1623. For this region, we determine the physical
parameters, T and N(H2), from the CAM observations and the gas density, n(H2),
is determined from the flux ratio of the [O I]63um and [O I]145um lines. For
the oxygen abundance, our analysis leads to essentially three possibilities:
(1) Extended low density gas with standard ISM O-abundance, (2) Compact high
density gas with standard ISM O-abundance and (3) Extended high density gas
with reduced oxygen abundance, [O/H] ~ 2E-5. As option (1) disregards valid [O
I] 145um data, we do not find it very compelling; we favour option (3), as
lower abundances are expected as a result of chemical cloud evolution, but we
are not able to dismiss option (2) entirely. Observations at higher angular
resolution than offered by the LWS are required to decide between these
possibilities.Comment: Accepted for publication in A&
Mixed-symmetry tensor conserved currents and AdS/CFT correspondence
We present the full list of conserved currents built of two massless spinor
fields in Minkowski space and their derivatives multiplied by Clifford algebra
elements. The currents have particular mixed-symmetry type described by Young
diagrams with one row and one column of arbitrary lengths and heights. Along
with Yukawa-like totally antisymmetric currents the complete set of constructed
currents exactly matches the spectrum of AdS mixed-symmetry fields arising in
the generalized Flato-Fronsdal theorem for two spinor singletons. As a
by-product, we formulate and study general properties of primary fields and
conserved currents of mixed-symmetry type.Comment: 17 pages; v2: typos corrected, clarifications and refs added; v3:
more explanations and refs added; contribution to the J.Phys.A special volume
on "Higher Spin Theories and AdS/CFT" edited by Matthias Gaberdiel and
Mikhail Vasilie
Cohomological BRST aspects of the massless tensor field with the mixed symmetry (k,k)
The main BRST cohomological properties of a free, massless tensor field that
transforms in an irreducible representation of GL(D,R), corresponding to a
rectangular, two-column Young diagram with k>2 rows are studied in detail. In
particular, it is shown that any non-trivial co-cycle from the local BRST
cohomology group H(s|d) can be taken to stop either at antighost number (k+1)
or k, its last component belonging to the cohomology of the exterior
longitudinal derivative H(gamma) and containing non-trivial elements from the
(invariant) characteristic cohomology H^{inv}(delta|d).Comment: Latex, 50 pages, uses amssym
How higher-spin gravity surpasses the spin two barrier: no-go theorems versus yes-go examples
Aiming at non-experts, we explain the key mechanisms of higher-spin
extensions of ordinary gravity. We first overview various no-go theorems for
low-energy scattering of massless particles in flat spacetime. In doing so we
dress a dictionary between the S-matrix and the Lagrangian approaches,
exhibiting their relative advantages and weaknesses, after which we high-light
potential loop-holes for non-trivial massless dynamics. We then review positive
yes-go results for non-abelian cubic higher-derivative vertices in constantly
curved backgrounds. Finally we outline how higher-spin symmetry can be
reconciled with the equivalence principle in the presence of a cosmological
constant leading to the Fradkin--Vasiliev vertices and Vasiliev's higher-spin
gravity with its double perturbative expansion (in terms of numbers of fields
and derivatives).Comment: LaTeX, 50 pages, minor changes, many refs added; version accepted for
publication in Reviews of Modern Physic
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