S. Pereira | Searcharxiv

arXiv2016

Measurements of the Atmospheric Electric Field through a Triangular Array and the Long-range Saharan Dust Electrification in Southern Portugal

Atmospheric electric field (AEF) measurements were carried out in three different sites forming a triangular array in Southern Portugal. The campaign was performed during the summer characterized by Saharan dust outbreaks; the 16th-17th July 2014 desert dust event is considered here. Evidence of long-range dust electrification is attributed to the air-Earth electrical current creating a positive space-charge inside of the dust layer. An increase of ~23 V/m is observed in AEF on the day of the dust event corresponding to space-charges of ~20-2 pCm-3 (charge layer thicknesses ~10-100 m). A reduction of AEF is observed after the dust event.

physics.ao-ph↗

arXiv2003

The static effective action for non-commutative QED at high temperature

In this paper, we systematically study the effective action for non-commutative QED in the static limit at high temperature. When $θp^{2}\ll 1$, where $θ$ represents the magnitude of the parameter for non-commutativity and $p$ denotes a typical external three momentum, we show that this leads naturally to a derivative expansion in this model. The study of the self-energy, in this limit, leads to nontrivial $θ$ dependent corrections to the electric and magnetic masses, which exist only above a certain critical temperature. The three point and the four point amplitudes are also studied as well as their relations to the Ward identities in this limit. We determine the closed form expression for the current involving only the spatial components of the gauge field and present the corresponding static effective action, which is gauge invariant.

hep-th↗