  Semileptonic flavor changing neutral current transitions with a pair of
neutrinos in the final state are very accurately determined in the standard
model (SM) and thus provide an accurate and sensitive probe for physics beyond
the SM. Until recently, the poor tagging efficiency for the $B\to K^{(*)}\nu
\bar{\nu}$ modes made them less advantageous as a probe of new physics (NP)
compared to the charged lepton counterparts. The most recent Belle II result on
$B\to K \nu \bar{\nu}$ uses an innovative inclusive tagging technique resulting
in a higher tagging efficiency; this together with previous BaBar and Belle
results indicates a possible enhancement in the branching fraction of $B^+\to
K^+ \nu \bar{\nu}$. A reanalysis of the full Belle dataset together with
upcoming Belle II dataset is expected to result in a much more precise
measurement of this mode. If the branching ratio is indeed found to be enhanced
with improved measurements, this would provide an unambiguous signal of NP
without uncertainties due to long-distance non-factorizable effects or power
corrections (in contrast to $B\to K^{(*)} \ell \ell$). We have explored the
possibilities of such an enhancement as a signal of NP within several
scenarios, which can also explain some of the other tensions observed in
neutral as well as charged current $B$-decays. In an effective field theory
approach, with the most general dimension-six Hamiltonian including light
right-handed neutrinos, we explore the viability of all scalar and vector
leptoquarks as well as the parameter space possible with a generic vector gauge
boson $Z^\prime$ model assuming minimal new particle content. While being
consistent with all data, correlations between the observed intriguing
discrepancies in $B$-decays are also obtained, which will discriminate between
the various NP scenarios.
