8 research outputs found
Localized Random Lasing Modes and a New Path for Observing Localization
We demonstrate that a knowledge of the density-of-states and the eigenstates
of a random system without gain, in conjunction with the frequency profile of
the gain, can accurately predict the mode that will lase first. Its critical
pumping rate can be also obtained. It is found that the shape of the
wavefunction of the random system remains unchanged as gain is introduced.
These results were obtained by the time-independent transfer matrix method and
finite-difference-time-domain (FDTD) methods. They can be also analytically
understood by generalizing the semi-classical Lamb theory of lasing in random
systems. These findings provide a new path for observing the localization of
light, such as looking for mobility edge and studying the localized states.
%inside the random systems..Comment: Sent to PRL. 3 figure
Perturbative Computation of the Gluonic Effective Action via Polyaokov's World-Line Path Integral
The Polyakov world-line path integral describing the propagation of gluon
field quanta is constructed by employing the background gauge fixing method and
is subsequently applied to analytically compute the divergent terms of the one
(gluonic) loop effective action to fourth order in perturbation theory. The
merits of the proposed approach is that, to a given order, it reduces to
performing two integrations, one over a set of Grassmann and one over a set of
Feynman-type parameters through which one manages to accomodate all Feynman
diagrams entering the computation at once.Comment: 21 page