  The missing transverse energy (MET) plus b-jets signature is very promising
for searches for the Higgs boson or new physics. Indeed, MET naturally arises
from unidentified particles such as neutrinos, neutralinos, gravitons, etc.,
and b-quarks are the main decay products of a low mass Higgs boson as well as
of several exotic particles. The main challenge is to identify and reject the
numerous standard model (SM) backgrounds that mimic this signature. This is
especially so for QCD multi-jet production, a large background due to
mis-measurement (rather than undetectable particles). We present
state-of-the-art data-driven and multivariate techniques to characterize and
reject this instrumental background. These techniques make analyses in this
signature as sensitive as those using lepton identification and allow probing
for rare SM processes. We describe searches for electroweak single top
production, a part of the observation of single top by CDF, and for a low mass
SM Higgs boson, one of the most sensitive among low mass Higgs searches at CDF.
We also present a measurement of the top pair cross-section in this signature,
and discuss other analyses and future prospects.
