  Supersymmetry, which extends the Standard Model (SM) by introducing
supersymmetric partners for the SM particles, can provide an elegant solution
to the hierarchy problem. One of the most important parameters in supersymmetry
is the mass of the supersymmetric partner to the top quark, referred to as
stop. In the absence of the stop signature in the previous searches at the LHC,
compressed stop searches in which the mass of the stop is close to the mass of
the lightest neutralino become more important. In scenarios with compressed
mass spectra, the momentum transfer to the decay products of the stop may be
small, leading to decay products with transverse momenta of only a few GeV.
Hence, the identification and reconstruction of those "soft" objects can play a
crucial role in the searches. In this article, recent results from the
compressed stop searches in pp collisions at $\sqrt{s}$ =13 TeV with the ATLAS
detector and new developments for soft b-hadron tagging techniques are
presented.
