Measuring the angle $\gamma$ from penguin decays at LHCb

In this paper we present first LHCb results on charmless charged two- and three-body $B$ meson decays. In particular, using the first picobarn of integrated luminosity, LHCb observed the $B^{0}\rightarrow K^{+}\pi^{-}$ and $B^{+}\rightarrow K^{+}\pi^{+}\pi^{-}$ decays. Such decays provide an interesting way to determine the angle $\gamma$ of the Unitary Triangle, thanks to the possible presence of New Physics in the penguin loops.