Searches for Light Exotics at LHCb

We report on the latest direct searches for light exotics at LHCb, conducted during Run I of LHC. This proceedings are divided into two sections, the first part will cover the search for the lepton number violating decay $B\to {\pi }^{+}{\mu }^{-}{\mu }^{-}$ while the second part will cover the search for a low mass dark boson in the decay $B^0\to K^{\ast 0}\chi$, with $\chi \to {\mu }^{+}{\mu }^{-}$ and $K^{\ast 0}\to K^{+}{\pi }^{-}$. The data used in these searches correspond to integrated luminosities of 1.0 and $2.0$ fb${}^{-1}$ collected in $pp$ collisions at centre of mass energies of $\sqrt{s}=7$ and 8 TeV in $pp$ collisions with the LHCb detector.