Any attempt to regularize a negative tension brane through a bulk scalar requires that this field is a ghost. One can try to improve in this aspect in a number of ways. For instance, it has been suggested to employ a field whose kinetic term is not sign definite, in the hope that the background may be overall stable. We show that this is not the case; the physical perturbations (gravity included) of the system do not extend across the zeros of the kinetic term; hence, all the modes are entirely localized either where the kinetic term is positive, or where it is negative; this second type of modes are ghosts. We show that this conclusion does not depend on the specific choice for the kinetic and potential functions for the bulk scalar.
|Original language||English (US)|
|Number of pages||8|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - Sep 8 2005|
Bibliographical noteFunding Information:
We thank Nemanja Kaloper, Stefan Groot Nibbelink and Maxim Pospelov for very useful discussions. This work has been supported in part by the Department of Energy under contract DE-FG02-94ER40823 at the University of Minnesota.