Hentschel, M; Ullmo, D; Baranger, HU, *Fermi-edge singularities in the mesoscopic x-ray edge problem.*,
Physical Review Letters, vol. 93 no. 17
(October, 2004),
pp. 176807, cond-mat/0402207 [15525108], [doi] .
**Abstract:**

*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 Fermi-edge singularities-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; in particular, 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.*