  The LHC search for nearly degenerate gluinos and neutralinos, which can
occur, for example, in SUSY axion models, is limited by the reduced missing
transverse momentum and effective mass in the events. We propose the use of
kinematic correlations between jets coming from initial state radiation (ISR)
in gluino pair production events at the 13 TeV LHC. A significant improvement
in the signal to background ratio is obtained for the highly compressed
gluino-neutralino search, by using cuts on the rapidity and azimuthal angle
separation between the pair of tagged jets with the highest transverse momenta.
Furthermore, the distribution of the azimuthal angle difference between the
tagged jets in the gluino-pair+jets process is found to be distinctly different
from the dominant background process of Z+jets. We also find quark and gluon
jet tagging methods to be useful in separating the signal, which contains a
higher fraction of gluon initiated jets compared to the dominant backgrounds.
