On the existence of internal modes of sine-Gordon kinks

Abstract

We study whether or not sine-Gordon kinks exhibit internal modes or ``quasimodes.'' By considering the response of the kinks to ac forces and initial distortions, we show that neither intrinsic internal modes nor ``quasimodes'' exist in contrast to previous reports. However, we do identify a different kind of internal mode bifurcating from the bottom edge of the phonon band which arises from the discretization of the system in the numerical simulations, thus confirming recent predictions.

4 pages, 2 figures, REVTeX, to appear as a Rapid Communication in Phys Rev E (July 1st)