Gauge fields in a string-cigar braneworld

In this work we investigate the properties of an Abelian gauge vector field in a thin and in a smoothed string-like braneworld, the so-called string-cigar model. This thick brane scenario satisfies the regularity conditions and it can be regarded as an interior and exterior string-like solution. The source undergoes a geometric Ricci flow which is connected to a variation of the bulk cosmological constant. The Ricci flow changes the width and amplitude of the massless mode at the brane core and recover the usual thin string-like behavior at large distances. By numerical means we obtain the Kaluza-Klein (KK) spectrum for both the thin brane and the string-cigar. It turns out that both models exhibit a mass gap between the massless and the massive modes and between the high and the low mass regimes. The KK modes are smooth near the brane and their amplitude are enhanced by the string-cigar core. The analogue Schr\"odinger potential is also tuned by the geometric flow.Comment: The discussion about the Kaluza-Klein spectrum of the gauge field was improved. Numerical analysis was adapted to the conventional notation on Kaluza-Klein number. Some graphics were modified for considering other notation. Results unchanged. References added. Corrected typos. 17 pages. 6 figures. To match version to appears in Physics Letters

Alterações na cobertura vegetal e no uso das terras entre 1972 e 2009 em área rural do município de Guararapes, SP.

Os produtos de sensoriamento remoto constituem ferramentas importantes para mapeamentos e monitoramentos do uso e da cobertura das terras. O mapeamento do uso e da cobertura das terras em área rural do Município de Guararapes (SP) nos anos de 1972 e 2009 foi realizado por meio de interpretação visual de fotografias aéreas (1972) e de imagens do sensor AVNIR do satélite ALOS (2009). As alterações verificadas entre esses dois anos foram caracterizadas e quantificadas, como subsídio para estudos da dinâmica agropecuária regional e de seus impactos ambientais e socioeconômicos, importantes para ações de planejamento e gestão territorial na região. As pastagens, que cobriam 77% da área de estudo em 1972, foram reduzidas para 45% em 2009, como consequência sobretudo da grande expansão da cultura da cana-de-açúcar

Neutral heavy lepton production at next high energy e+e−e^+e^- linear colliders

The discovery potential for detecting new heavy Majorana and Dirac neutrinos at some recently proposed high energy $e^+e^-$ colliders is discussed. These new particles are suggested by grand unified theories and superstring-inspired models. For these models the production of a single heavy neutrino is shown to be more relevant than pair production when comparing cross sections and neutrino mass ranges. The process $e^+e^- \longrightarrow {\nu} e^{\pm} W^{\mp}$ is calculated including on-shell and off-shell heavy neutrino effects. We present a detailed study of cross sections and distributions that shows a clear separation between the signal and standard model contributions, even after including hadronization effects.Comment: 4 pages including 15 figures, 1 table. RevTex. Accepted in Physical Review