Papers by Nicolas Boulanger
Symmetry
Considering the Poincaré group ISO(d−1,1) in any dimension d>3, we characterise the coadjoint ... more Considering the Poincaré group ISO(d−1,1) in any dimension d>3, we characterise the coadjoint orbits that are associated with massive and massless particles of discrete spin. We also comment on how our analysis extends to the case of continuous spin.
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Physics
Since the pioneering works of Newton (1643–1727), mechanics has been constantly reinventing itsel... more Since the pioneering works of Newton (1643–1727), mechanics has been constantly reinventing itself: reformulated in particular by Lagrange (1736–1813) then Hamilton (1805–1865), it now offers powerful conceptual and mathematical tools for the exploration of dynamical systems, essentially via the action-angle variables formulation and more generally through the theory of canonical transformations. We propose to the (graduate) reader an overview of these different formulations through the well-known example of Foucault’s pendulum, a device created by Foucault (1819–1868) and first installed in the Panthéon (Paris, France) in 1851 to display the Earth’s rotation. The apparent simplicity of Foucault’s pendulum is indeed an open door to the most contemporary ramifications of classical mechanics. We stress that adopting the formalism of action-angle variables is not necessary to understand the dynamics of Foucault’s pendulum. The latter is simply taken as well-known and simple dynamical s...
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Physics of Particles and Nuclei Letters
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Journal of High Energy Physics
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The European Physical Journal C
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Journal of High Energy Physics
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Journal of High Energy Physics
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Physics Letters B
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Journal of Physics A: Mathematical and Theoretical
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Journal of High Energy Physics
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It is a general belief that the only possible way to consistently deform the Pauli-Fierz action, ... more It is a general belief that the only possible way to consistently deform the Pauli-Fierz action, changing also the gauge algebra, is general relativity. Here we show that a different type of deformation exists in three dimensions if one allows for PT non-invariant terms. The new gauge algebra is different from that of diffeomorphisms. Furthermore, this deformation can be generalized to the case of a collection of massless spin-two fields. In this case it describes a consistent interaction among them.
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Journal of High Energy Physics, 2016
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Journal of Physics A: Mathematical and Theoretical, 2016
ABSTRACT We consider four-dimensional Higher-Spin Theory at the first nontrivial order correspond... more ABSTRACT We consider four-dimensional Higher-Spin Theory at the first nontrivial order corresponding to the cubic action. All Higher-Spin interaction vertices are explicitly obtained from Vasiliev's equations. In particular, we obtain the vertices that are not determined solely by the Higher-Spin algebra structure constants. The dictionary between the Fronsdal fields and Higher-Spin connections is found and the corrections to the Fronsdal equations are derived. These corrections turn out to involve derivatives of arbitrary order. We observe that the vertices not determined by the Higher-Spin algebra produce naked infinities, when decomposed into the minimal derivative vertices and improvements. Therefore, standard methods can only be used to check a rather limited number of correlation functions within the HS AdS/CFT duality. A possible resolution of the puzzle is discussed.
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Classical and Quantum Gravity, 2015
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Journal of High Energy Physics, 2015
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We present a list of all inequivalent bosonic covariant free particle wave equations in a flat sp... more We present a list of all inequivalent bosonic covariant free particle wave equations in a flat spacetime of arbitrary dimension. The wave functions are assumed to have a finite number of components. We relate these wave equations to equivalent versions obtained following other approaches.
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We present some generalities of unfolded on-shell dynamics that are useful in analyzing the BMV c... more We present some generalities of unfolded on-shell dynamics that are useful in analyzing the BMV conjecture for mixed-symmetry fields in constantly curved backgrounds. In particular we discuss the unfolded notion of local degrees of freedom in theories with and without gravity and with and without massive deformation parameters, using the language of Weyl zero-form modules and their duals. 1 Work supported by a “Progetto Italia ” fellowship. F.R.S.-FNRS associate researcher on leave from the Service de Mécanique et Gravitation, Université de Mons-Hainaut, Belgium.
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Following the general formalism presented in 0812.3615 — referred to as Paper I — we derive the u... more Following the general formalism presented in 0812.3615 — referred to as Paper I — we derive the unfolded equations of motion for tensor fields of arbitrary shape and mass in constantly curved backgrounds by radial reduction of Skvortsov’s equations in one higher dimension. The complete unfolded system is embedded into a single master field, valued in a tensorial Schur module realized equivalently via either bosonic (symmetric basis) or fermionic (anti-symmetric basis) vector oscillators. At critical masses the reduced Weyl zero-form modules become indecomposable. We explicitly project the latter onto the submodules carrying Metsaev’s massless representations. The remainder of the reduced system contains a set of Stückelberg fields and dynamical potentials that leads to a smooth flat limit in accordance with the Brink–Metsaev–Vasiliev (BMV) conjecture. In the unitary massless cases in AdS, we identify the Alkalaev–Shaynkman–Vasiliev frame-like potentials and explicitly disentangle th...
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Papers by Nicolas Boulanger