  We study the x-ray edge problem for a chaotic quantum dot or nanoparticle
displaying mesoscopic fluctuations. In the bulk, x-ray physics is known to
produce deviations from the naively expected photoabsorption cross section in
the form of a peaked or rounded edge. For a coherent system with chaotic
dynamics, we find substantial changes and in particular that a photoabsorption
cross section showing a rounded edge in the bulk will change to a slightly
peaked edge on average as the system size is reduced to a mesoscopic (coherent)
scale.
