1,068 research outputs found
On the relation between local and geometric Lagrangians for higher spins
Equations of motion for free higher-spin gauge fields of any symmetry can be
formulated in terms of linearised curvatures. On the other hand, gauge
invariance alone does not fix the form of the corresponding actions which, in
addition, either contain higher derivatives or involve inverse powers of the
d'Alembertian operator, thus introducing possible subtleties in degrees of
freedom count. We suggest a path to avoid ambiguities, starting from local,
unconstrained Lagrangians previously proposed, and integrating out the
auxiliary fields from the functional integral, thus generating a unique
non-local theory expressed in terms of curvatures.Comment: 14 pages. Contribution to the proceedings of the 1st Mediterranean
Conference on Classical and Quantum Gravity, Kolymbary (Crete, Greece)
September 14-18 200
Multimetric Supergravities
Making use of integral forms and superfield techniques we propose
supersymmetric extensions of the multimetric gravity Lagrangians in dimensions
one, two, three and four. The supersymmetric interaction potential covariantly
deforms the bosonic one, producing in particular suitable super-symmetric
polynomials generated by the Berezinian. As an additional application of our
formalism we construct supersymmetric multi-Maxwell theories in dimensions
three and four.Comment: 37 pages, Latex2e, no figure
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 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 .Comment: 19 page
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
Estimation of the methane emission factor for the Italian Mediterranean buffalo
In order to contribute to the improvement of the national greenhouse gas emission inventory, this work aimed at estimating a country-specific enteric methane (CH4) emission factor for the Italian Mediterranean buffalo. For this purpose, national agriculture statistics, and information on animal production and farming conditions were analysed, and the emission factor was estimated using the Tier 2 model of the Intergovernmental Panel on Climate Change. Country-specific CH4 emission factors for buffalo cows (630 kg body weight, BW) and other buffalo (313 kg BW) categories were estimated for the period 1990–2004. In 2004, the estimated enteric CH4 emission factor for the buffalo cows was 73 kg/head per year, whereas that for other buffalo categories it was 56 kg/head per year. Research in order to determine specific CH4 conversion rates at the predominant production system is suggested
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
Asymptotic symmetries and charges at null infinity: from low to high spins
Weinberg's celebrated factorisation theorem holds for soft quanta of
arbitrary integer spin. The same result, for spin one and two, has been
rederived assuming that the infinite-dimensional asymptotic symmetry group of
Maxwell's equations and of asymptotically flat spaces leave the S-matrix
invariant. For higher spins, on the other hand, no such infinite-dimensional
asymptotic symmetries were known and, correspondingly, no a priori derivation
of Weinberg's theorem could be conjectured. In this contribution we review the
identification of higher-spin supertranslations and superrotations in as
well as their connection to Weinberg's result. While the procedure we follow
can be shown to be consistent in any , no infinite-dimensional enhancement
of the asymptotic symmetry group emerges from it in , thus leaving a
number of questions unanswered.Comment: 11 pages. Contribution to the proceedings of Quarks-2018, XXth
International Seminar on High Energy Physics; Valday, Russia, 27 May - 2 June
201
Geometric Lagrangians for massive higher-spin fields
Lagrangians for massive, unconstrained, higher-spin bosons and fermions are
proposed. The idea is to modify the geometric, gauge invariant Lagrangians
describing the corresponding massless theories by the addition of suitable
quadratic polynomials. These polynomials provide generalisations of the
Fierz-Pauli mass term containing all possible traces of the basic field. No
auxiliary fields are needed.Comment: 50 pages, 3 appendices; typos corrected, comments and references
added. To appear in Nucl. Phys.
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.
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