Hawking radiation for non asymptotically flat dilatonic black holes using gravitational anomaly

The $d$-dimensional scalar field action may be reduced, in the background geometry of a black hole, to a 2-dimensional effective action. In the near horizon region, it appears a gravitational anomaly: the energy-momentum tensor of the scalar field is not conserved anymore. This anomaly is removed by introducing a term related to the Hawking temperature of the black hole. Even if the temperature term introduced is not covariant, a gauge transformation may restore the covariance. We apply this method to compute the temperature of the black hole of the dilatonic non asymptotically flat black holes. We compare the results with those obtained through other methods.Comment: Latex file, 22 pages. Some discussions enlarged. New references. Accepted for publication in the European Physical Journal

Excitonic effects in the optical properties of CdSe nanowires

Using a first-principle approach beyond density functional theory we calculate the electronic and optical properties of small diameter CdSe nanowires.Our results demonstrate how some approximations commonly used in bulk systems fail at this nano-scale level and how indispensable it is to include crystal local fields and excitonic effects to predict the unique optical properties of nanowires. From our results, we then construct a simple model that describes the optical gap as a function of the diameter of the wire, that turns out to be in excellent agreement with experiments for intermediate and large diameters.Comment: submitte

On a generalized gravitational Aharonov-Bohm effect

A massless spinor particle is considered in the background gravitational field due to a rotating body. In the weak field approximation it is shown that the solution of the Weyl equations depend on the angular momentum of the rotating body, which does not affect the curvature in this approximation. This result may be looked upon as a generalization of the gravitational Aharonov-Bohm effect.Comment: 10 pages, LATEX fil

Construction of the B88 exchange-energy functional in two dimensions

We construct a generalized-gradient approximation for the exchange-energy density of finite two-dimensional systems. Guided by non-empirical principles, we include the proper small-gradient limit and the proper tail for the exchange-hole potential. The observed performance is superior to that of the two-dimensional local-density approximation, which underlines the usefulness of the approach in practical applications