Mode competition in superradiant scattering of matter waves
  Superradiant Rayleigh scattering in a Bose gas released from an optical lattice is analyzed with incident light pumping at the Bragg angle for resonant light diffraction. We show competition between superradiance scattering into the Bragg mode and into end-fire modes clearly leads to suppression of the latter at even relatively low lattice depths. A quantum light-matter interaction model is proposed for qualitatively explaining this result. 
Thibault Vogt, Bo Lu, XinXing Liu, Xu Xu, Xiaoji Zhou, Xuzong Chen
cond-mat.quant-gas physics.atom-ph