Gravitational Lensing by Asymptotically Flat Wormholes

Natural wormholes and its astrophysical signatures have been sugested in various oportunities. By applying the strong field limit of gravitational lensing theory, we calculate the deflection angle and magnification curves produced by Morris-Thorne wormholes in asimptotically flat space-times. The results show that wormholes act like convergent lenses. Therefore, we show that it is hard to distinguish them from black holes using the deflection's angle of the gravitational lens effect, in contrast with the results reported by Cramer et.al. and Safanova et.al. However, we also show that it is possible, in principle, distinguish them by the magnification curves, in particular, by observing the position of the peak of the Einstein's ring.Comment: 9 pages, 14 figure

Effective theories and constraints on new phyhsics

Anomalous moments of the top quark arises from one loop corrections to the vertices $\bar t t g$ and $\bar t t \gamma$. We study these anomalous couplings in different frameworks: effective theories, Standard Model and 2HDM. We use available experimental results in order to get bounds on these anomalous couplings.Comment: 8 pages, 2 figures, talk presented by R. Martinez at the X Mexican School of Particles and Fields, Playa del Carmen, Mexico, 200