Search for Associated Production of $Z$ and Higgs Bosons in the $ \nu \nu bb$ Final State in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV

We present a search for a low mass Standard Model Higgs boson produced in association with a $Z$ boson decaying invisibly into a pair of neutrinos at a center-of-mass energy of $\sqrt{s}=$1.96~TeV with the D0 detector at the Fermilab Tevatron collider. The final state is characterized by the presence of two $b$-tagged jets from the Higgs boson decay and a large imbalance in the transverse energy of the event. This channel is very powerful because of the large $Z\to \nu\nu$ branching ratio, but is experimentally very challenging because of the large QCD backgrounds and absence of visible leptons in the final state. The result with a data set up to 5.2~fb$^{-1}$ and recent improvements to the sensitivity will be discussed.