Large Hadron Collider reach for supersymmetric models with compressed   mass spectra
  Many theoretical and experimental results on the reach of the Large Hadron Collider are based on the mSUGRA-inspired scenario with universal soft supersymmetry breaking parameters at the apparent gauge coupling unification scale. We study signals for supersymmetric models in which the sparticle mass range is compressed compared to mSUGRA, using cuts like those employed by ATLAS for 2010 data. The acceptance and the cross-section times acceptance are found for several model lines that employ a compression parameter to smoothly interpolate between the mSUGRA case and the extreme case of degenerate gaugino masses at the weak scale. For models with moderate compression, the reach is not much worse, and can even be substantially better, than the mSUGRA case. For very compressed mass spectra, the acceptances are drastically reduced, especially when a more stringent effective mass cut is chosen. 
Thomas J. LeCompte and Stephen P. Martin
hep-ph