2,465 research outputs found

### Gravitational Couplings of Higher Spins from String Theory

We calculate the interaction 3-vertex of two massless spin 3 particles with a
graviton using vertex operators for spin 3 fields in open string theory,
constructed in our previous work. The massless spin 3 fields are shown to
interact with the graviton through the linearized Weyl tensor, reproducing the
result by Boulanger, Leclercq and Sundell. This is consistent with the general
structure of the non-Abelian $2-s-s$ couplings, implying that the minimal
number of space-time derivatives in the interaction vertices of two spin s and
one spin 2 particle is equal to $2s-2$.Comment: 19 page

### 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

### On spin 2 electromagnetic interactions

In this paper we (re)consider the problem of electromagnetic interactions for
massless spin 2 particles and show that in $(A)dS$ spaces with non-zero
cosmological constant it is indeed possible (at least in linear approximation)
to switch on minimal electromagnetic interactions supplemented by third
derivative non-minimal ones which are necessary to restore gauge invariance.Comment: 5 pages, no figure

### Constituent gluon interpretation of glueballs and gluelumps

Arguments are given that support the interpretation of the lattice QCD
glueball and gluelump spectra in terms of bound states of massless constituent
gluons with helicity-1. In this scheme, the mass hierarchy of the currently
known gluelumps and glueballs is mainly due to the number of constituent gluons
and can be understood within a simple flux tube model. It is also argued that
the lattice QCD $0^{+-}$ glueball should be seen as a four-gluon bound state.
The flux tube model allows for a parameter-free computation of its mass, which
is in good agreement with lattice QCD.Comment: 3 figures, use of package youngta

### 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

### Compactifications of conformal gravity

We study conformal theories of gravity, i.e. those whose action is invariant
under the local transformation g_{\mu\nu} -> \omega^2 (x) g_{\mu\nu}. As is
well known, in order to obtain Einstein gravity in 4D it is necessary to
introduce a scalar compensator with a VEV that spontaneously breaks the
conformal invariance and generates the Planck mass. We show that the
compactification of extra dimensions in a higher dimensional conformal theory
of gravity also yields Einstein gravity in lower dimensions, without the need
to introduce the scalar compensator. It is the field associated with the size
of the extra dimensions (the radion) who takes the role of the scalar
compensator in 4D. The radion has in this case no physical excitations since
they are gauged away in the Einstein frame for the metric. In these models the
stabilization of the size of the extra dimensions is therefore automatic.Comment: 13 page

### Gauge fields and infinite chains of dualities

We show that the particle states of Maxwell's theory, in $D$ dimensions, can
be represented in an infinite number of ways by using different gauge fields.
Using this result we formulate the dynamics in terms of an infinite set of
duality relations which are first order in space-time derivatives. We derive a
similar result for the three form in eleven dimensions where such a possibility
was first observed in the context of E11. We also give an action formulation
for some of the gauge fields. In this paper we give a pedagogical account of
the Lorentz and gauge covariant formulation of the irreducible representations
of the Poincar\'e group, used previously in higher spin theories, as this plays
a key role in our constructions. It is clear that our results can be
generalised to any particle.Comment: 37 page

### Massless spin-two field S-duality

We present a review of the homological algebra tools involved in the standard de Rham theory and their subsequent generalizations relevant for the understanding of free massless higher spin gauge structure. M-theory arguments suggest the existence of an extension of (Abelian) S-duality symmetry for non-Abelian gauge theories, like the four dimensional Yang-Mills or Einstein theories. Some no-go theorems prove that this extension, if it exists, should fall outside the scope of local perturbative field theory

### H2 formation and excitation in the Stephan's Quintet galaxy-wide collision

Context. The Spitzer Space Telescope has detected a powerful (L(H2)~10^41 erg
s-1) mid-infrared H2 emission towards the galaxy-wide collision in the
Stephan's Quintet (SQ) galaxy group. This discovery was followed by the
detection of more distant H2-luminous extragalactic sources, with almost no
spectroscopic signatures of star formation. These observations set molecular
gas in a new context where one has to describe its role as a cooling agent of
energetic phases of galaxy evolution. Aims. The SQ postshock medium is observed
to be multiphase, with H2 gas coexisting with a hot (~ 5 10^6 K), X-ray
emitting plasma. The surface brightness of H2 lines exceeds that of the X-rays
and the 0-0 S(1) H2 linewidth is ~ 900 km s-1, of the same order of the
collision velocity. These observations raise three questions we propose to
answer: (i) Why H2 is present in the postshock gas ? (ii) How can we account
for the H2 excitation ? (iii) Why H2 is a dominant coolant ? Methods. We
consider the collision of two flows of multiphase dusty gas. Our model
quantifies the gas cooling, dust destruction, H2 formation and excitation in
the postshock medium. Results. (i) The shock velocity, the post-shock
temperature and the gas cooling timescale depend on the preshock gas density.
The collision velocity is the shock velocity in the low density volume filling
intercloud gas. This produces a ~ 5 10^6 K, dust-free, X-ray emitting plasma.
The shock velocity is smaller in clouds. We show that gas heated to
temperatures less than 10^6 K cools, keeps its dust content and becomes H2
within the SQ collision age (~ 5 10^6 years). (ii) Since the bulk kinetic
energy of the H2 gas is the dominant energy reservoir, we consider that the H2
emission is powered by the dissipation of kinetic turbulent energy. (Abridged)Comment: 19 pages, 12 figures. Accepted for publication in Astronomy &
Astrophysics Minor editing and typo

### Socio-Legal Studies in Germany and the UK: Theory and Methods

This Special Issue considers the situated and contextualized development of socio legal, or law and society, scholarship within two materially different legal and academic cultures, namely Germany and the United Kingdom, with a view to achieving a better understanding of why and how such differences in understanding and practice have arisen. The contributions are grouped into three themes. The first reflects upon the influence of institutional contexts and scholarly traditions in terms of the development of those approaches that come under the banner of socio legal studies. The second features contributions that adopt a comparative perspective in terms of selected areas of law, pointing to notably different approaches taken in Germany and the UK, and considering the development of these respective situations. The third looks at the key contemporary trends, theoretical applications, and methodological approaches taken within both countriesâ€™ socio legal academic contexts

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