Bounds on the electromagnetic interactions of excited spin-3/2 leptons

We discuss possible deviations from QED produced by a virtual excited spin-3/2 lepton in the reaction $e^+e^- \longrightarrow 2\gamma$. Data recorded by the OPAL Collaboration at a c.m. energy $\sqrt{s} = 183 GeV$ are used to establish bounds on the nonstandard-lepton mass and coupling strengths.Comment: Latex, 5 pages, 7 ps figures. To be published in Phys. Rev.

Caracterização da variabilidade genética de populações locais de pimenta dedo-de-moça, utilizando marcadores RAPD.

bitstream/item/30461/1/boletim-80.pd

Em busca de sustentabilidade agrícola: tópicos em educação ambiental, agroecologia, agroecossistemas e biodiversidade

bitstream/item/33954/1/documento-210.pd

Detection of Spiral photons in Quantum Optics

We show that a new type of photon detector, sensitive to the gradients of electromagnetic fields, should be a useful tool to characterize the quantum properties of spatially-dependent optical fields. As a simple detector of such a kind, we propose using magnetic dipole or electric quadrupole transitions in atoms or molecules and apply it to the detection of spiral photons in Laguerre-Gauss (LG) beams. We show that LG beams are not true hollow beams, due to the presence of magnetic fields and gradients of electric fields on beam axis. This approach paves the way to an analysis at the quantum level of the spatial structure and angular momentum properties of singular light beams.Comment: 5 pages, 4 figure