27585824
Low-energy electron-phonon effective action from symmetry analysis
This work was partially supported PICT ANPCYT Grants No. 20350 and No. 00849, PIP CONICET Grants No. 1691 and No.0396, and Spanish MECD Grants No. FIS2011-23712 and No.PIB2010BZ-00512.
21580104
Non(anti)commutative superspace with coordinate-dependent deformation
We consider non(anti)commutative superspace with coordinate-dependent deformation parameters C{sup {alpha}}{sup {beta}}. We show that a chiral N=1/2 supersymmetry can be defined and that chiral and antichiral superfields are still closed under the Moyal-Weyl associative product implementing the deformation. A consistent N=1/2 super Yang-Mills deformed theory can be constructed provided C{sup {alpha}}{sup {beta}} satisfies a suitable condition which can be connected with the graviphoton background at the origin of the deformation. After adding matter, we also discuss the Konishi anomaly and the gluino condensation.
45490561
Cosmic rays from decaying vortons
The flux of high energy cosmic rays coming from the decay of vortons is estimated. If the abundance of loops corresponding to a superconductivity scale coincident with that of the string formation is corrected to be compatible with the critical density of universe, it is found that the emission of one carrier per vorton may produce a flux of one cosmic ray event per km2 of detector and per year.
15742247
A coordinate-dependent superspace deformation from string theory
Starting from a type II superstring model defined on R2,2 × CY6 in a linear graviphoton background, we derive a coordinate dependent C-deformed = 1, d = 2+2 superspace. The chiral fermionic coordinates θ satisfy a Clifford algebra, while the other coordinate algebra remains unchanged. We find a linear relation between the graviphoton field strength and the deformation parameter. The null coordinate dependence of the graviphoton background allows to extend the results to all orders in α'.
115622991
Born-Infeld action and Supersymmetry
In the thesis we analize different problems related to the supersymmetric extension of the Dirac-Born-Infeld action. In chapter 2 we introduce the DBI action and show how it appears in string theory, we discuss also it's connection with Dp-branes. Chapter 3 is a self contained introduction to supersymmetry, with emphasis on BPS states. In chapter 4 we construct the N = 2 supersymmetric extension of the Born-Infeld-Higgs in three space-time dimensions and discuss it's BPS states and Bogomol'nyi bounds. In chapter 5 we construct the N = 1 supersymmetric extension of the non-abelian Born-Infeld theory in four space-time dimensions. Chapter 6 deals with the analisis of BPS and non-BPS solutions of the Dirac-Born-Infeld action and their interpretation in superstring theory. Chapter 7 is devoted to the conclusions. Three appendix complete the work. 1 Agradecimientos En primer lugar quiero agradecer a Fidel, por el infatigable estímulo que me brindó en estos tres años, por su incisivo carácter a la hora de discutir y por todo lo que me enseñó. A los chicos de La Plata y Buenos
15105325
Plane Waves and Vacuum Interpolation
A 1 -BPS family of time dependent plane wave spacetimes which give rise to exactly solvable string backgrounds is presented. In particular a solution which interpolates between Minkowski spacetime and the maximally supersymmetric homogeneous plane wave along a timelike direction is analyzed. We work in d = 4, N = 2 supergravity, but the results can be easily extended to d = 10,11. The conformal boundary of a particular class of solutions is studied.
118547077
A new analysis of the GJ581 extrasolar planetary system
We have done a new analysis of the available observations of the GJ581 exoplanetary system. Today this system is controversial due to choices that can be done in the orbital determination. The main ones are the occurrence of aliases and the additional bodies—the planets f and g—announced in Vogt et al. (Astrophys J 723:954–965, 2010). Any dynamical study of exoplanets requires the good knowledge of the orbital elements and the investigations involving the planet g are particularly interesting, since this body would lie in the habitable zone (HZ) of the star GJ581. This region, for this system, is very attractive of the dynamical point of view due to several resonances of two and three bodies present there. In this work, we investigate the conditions under which the planet g may exist. We stress the fact that the planet g is intimately related with the orbital elements of the planet d; more precisely, we conclude that it is not possible to disconnect its existence from the determination of the eccentricity of the planet d. Concerning the planet f, we have found one solution with period ≈450 days, but we are judicious about any affirmation concerning this body because its signal is in the threshold of detection and the high period is in a spectral region where the occurrence of aliases is very common. Besides, we outline some dynamical features of the HZ with the dynamical map and point out the role played by some resonances laying there.