Eur. Phys. J. C (2009) 63: 157-162
https://doi.org/10.1140/epjc/s10052-009-1060-9

Regular Article - Theoretical Physics

Planar Dirac diffusion

¹ Department of Applied Mathematics, University of Campinas, P.O. Box 6065, SP, 13083-970, Campinas, Brazil
² Department of Physics, University of Lecce and INFN Lecce, P.O. Box 193, CAP, 73100, Lecce, Italy

^* e-mail: deleo@ime.unicamp.br

Received: 2 April 2009
Published online: 10 June 2009

Abstract

We present the results of the planar diffusion of a Dirac particle by step and barrier potentials, when the incoming wave impinges at an arbitrary angle with the potential. Except for right-angle incidence this process is characterized by the appearance of spin flip terms. For the step potential, spin flip occurs for both transmitted and reflected waves. However, we find no spin flip in the transmitted barrier result. This is surprising because the barrier result may be derived directly from a two-step calculation. We demonstrate that the spin flip cancellation indeed occurs for each “particle” (wave packet) contribution.