Jihad Mourad

Unconstrained higher spins of mixed symmetry I. Bose fields

This is the first of two papers devoted to the local “metric-like” unconstrained Lagrangians and field equations for higher-spin gauge fields of mixed symmetry in flat space. Here we complete the previous constrained formulation of Labastida for Bose fields. We thus recover his Lagrangians via the Bianchi identities, before extending them to their “minimal” unconstrained form with higher derivatives of the compensator fields and to yet another, non-minimal, form with only two-derivative terms. We also identify classes of these systems that are invariant under Weyl-like symmetries.

A note on 'symmetric' vielbeins in bimetric, massive, perturbative and non perturbative gravities

A bstractWe consider a manifold endowed with two different vielbeins

On higher spin interactions with matter

{E^A}_{\mu }

Effective action in a higher-spin background

and

Covariant constraints in ghost free massive gravity

{L^A}_{\mu }

Charged and uncharged D-branes in various string theories

corresponding to two different metrics

D-branes in string theory Melvin backgrounds

{g_{{\mu \nu }}}

Comments on higher‐spin holography

and fμν. Such a situation arises generically in bimetric or massive gravity (including the recently discussed version of de Rham, Gabadadze and Tolley), as well as in perturbative quantum gravity where one vielbein parametrizes the background space-time and the other the dynamical degrees of freedom. We determine the conditions under which the relation

The continuous spin limit of higher spin field equations

{g^{{\mu \nu }}}{E^A}_{\mu }{L^B}_{\nu }={g^{{\mu \nu }}}{E^B}_{\mu }{L^A}_{\nu }

Time- and space-dependent backgrounds from non-supersymmetric strings

can be imposed (or the “Deser-van Nieuwenhuizen” gauge chosen). We clarify and correct various statements which have been made about this issue. We show in particular that in D = 4 dimensions, this condition is always equivalent to the existence of a real matrix square root of