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Dive into the research topics where A. Bérard is active.

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Featured researches published by A. Bérard.


Physics Letters A | 2006

Spin Hall effect and Berry phase of spinning particles

A. Bérard; Hervé Mohrbach

Abstract We consider the adiabatic evolution of the Dirac equation in order to compute its Berry curvature in momentum space. It is found that the position operator acquires an anomalous contribution due to the non-Abelian Berry gauge connection making the quantum mechanical algebra noncommutative. A generalization to any known spinning particles is possible by using the Bargmann–Wigner equation of motions. The noncommutativity of the coordinates is responsible for the topological spin transport of spinning particles similarly to the spin Hall effect in spintronic physics or the Magnus effect in optics. As an application we predict new dynamics for nonrelativistic particles in an electric field and for photons in a gravitational field.


Physical Review D | 2004

monopole and Berry phase in momentum space in noncommutative quantum mechanics

A. Bérard; Hervé Mohrbach

To build genuine generators of the rotations group in noncommutative quantum mechanics, we show that it is necessary to extend the noncommutative parameter


Physics Letters A | 1999

Dirac monopole with Feynman brackets

A. Bérard; Yves Grandati; H. Mohrbach

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European Physical Journal C | 2009

Berry curvature in graphene: a new approach

Pierre Gosselin; A. Bérard; Hervé Mohrbach; Subir Ghosh

to a field operator, which proves to be only momentum dependent. We find consequently that this field must be obligatorily a dual Dirac monopole in momentum space. Recent experiments in the context of the anomalous Hall effect provide evidence for a monopole in the crystal momentum space. We suggest a connection between the noncommutative field and the Berry curvature in momentum space which is at the origin of the anomalous Hall effect.


Journal of Mathematical Physics | 1999

Magnetic monopole in the Feynman’s derivation of Maxwell equations

A. Bérard; Yves Grandati; Hervé Mohrbach

Abstract We introduce the magnetic angular momentum as a consequence of the structure of the sO(3) Lie algebra defined by the Feynman brackets. The Poincare momentum and Dirac magnetic monopole appear as a direct result of this framework.


American Journal of Physics | 2008

Inverse problem and Bertrand’s theorem

Yves Grandati; A. Bérard; Ferhat Ménas

In the present paper we have directly computed the Berry curvature terms relevant for graphene in the presence of an inhomogeneous lattice distortion. We have employed the generalized Foldy–Wouthuysen framework, developed by some of us. We show that a non-constant lattice distortion leads to a valley–orbit coupling which is responsible for a valley–Hall effect. This is similar to the valley–Hall effect induced by an electric field proposed in the literature and is the analogue of the spin–Hall effect in semiconductors. Our general expressions for Berry curvature, for the special case of homogeneous distortion, reduce to the previously obtained results. We also discuss the Berry phase in the quantization of cyclotron motion.


arXiv: Classical Physics | 2000

Lorentz-Covariant Hamiltonian Formalism

A. Bérard; Hervé Mohrbach; Pierre Gosselin

In 1992, Dyson published Feynman’s proof of the homogeneous Maxwell equations assuming only the Newton’s law of motion and the commutation relations between position and velocity for a nonrelativistic particle. Recently Tanimura gave a generalization of this proof in a relativistic context. Using the Hodge duality we extend his approach in order to derive the two groups of Maxwell equations with a magnetic monopole in flat and curved spaces.


Celestial Mechanics and Dynamical Astronomy | 2009

Duality properties of Gorringe–Leach equations

Yves Grandati; A. Bérard; Hervé Mohrbach

Bertrand’s theorem is formulated as the solution of an inverse problem for classical one-dimensional motion. We show that the solutions of this problem, if suitably restricted, can be obtained by solving an elementary equation. This approach provides a compact and elegant proof of Bertrand’s theorem.


International Journal of Theoretical Physics | 2000

Electric and Magnetic Monopoles from a Lorentz- Covariant Hamiltonian

A. Bérard; H. Mohrbach

The dynamics of a classical system can be expressed by means of Poissonbrackets. In this paper we generalize the relation between the usual noncovariantHamiltonian and the Poisson brackets to a covariant Hamiltonian and new bracketsin the frame of Minkowski space. These brackets can be related to those usedby Feynman in his derivation Maxwells equations. The case of curved space isalso considered with the introduction of Christoffel symbols, covariant derivatives,and curvature tensors.


Central European Journal of Physics | 2011

On Peres approach to Fradkin-Bacry-Ruegg-Souriau’s perihelion vector

Yves Grandati; A. Bérard; Hervé Mohrbach

In the category of motions preserving the angular momentum direction, Gorringe and Leach exhibited two classes of differential equations having elliptical orbits. After enlarging slightly these classes, we show that they are related by a duality correspondence of the Arnold–Vassiliev type. The specific associated conserved quantities (Laplace–Runge–Lenz vector and Fradkin–Jauch–Hill tensor) are then dual reflections of each other.

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Pierre Gosselin

Centre national de la recherche scientifique

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P. Grangé

University of Montpellier

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Ferhat Ménas

École Normale Supérieure

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J. Lages

University of Franche-Comté

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Subir Ghosh

Indian Statistical Institute

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