RARE AND RADIATIVE DECAYS AT LHCb

Rare and radiative b-hadron decays are sensitive probes of New Physics (NP). One sensitive measurement is the polarisation of the photon emitted in a $b$ → $s$$\gamma$ transition, predominantly left-handed in the Standard Model (SM). Recent results by the LHCb collaboration are presented: the first observation of $\Lambda$ $_{b}^{0}$ → $\Lambda$$\gamma$ and the time-dependent analysis of $B$$_{s}^{0}$ → φ$\gamma$, which provides constraints on right-handed currents contribution.