Ullmo, D; Jiang, H; Yang, W; Baranger, HU, *Interactions and broken time-reversal symmetry in chaotic quantum dots*,
Physical Review B - Condensed Matter and Materials Physics, vol. 71 no. 20
(2005),
pp. 201310(R) [pdf], [doi] .
**Abstract:**

*When treating interactions in quantum dots within a random-phase- approximation (RPA)-like approach, time-reversal symmetry plays an important role as higher-order terms-the Cooper series-need to be included when this symmetry is present. Here we consider model quantum dots in a magnetic field weak enough to leave the dynamics of the dot chaotic, but strong enough to break time-reversal symmetry. The ground-state spin and addition energy for dots containing 120-200 electrons are found using local spin-density-functional theory, and we compare the corresponding distributions with those derived from an RPA-like treatment of the interactions. The agreement between the two approaches is very good, significantly better than for analogous calculations in the presence of time-reversal-symmetry. This demonstrates that the discrepancies between the two approaches in the time-reversal symmetric case indeed originate from the Cooper channel, indicating that these higher-order terms might not be properly taken into account in the spin-density-functional calculations. © 2005 The American Physical Society.*