Search for Lepton Flavour Violation at LHCb

Charged Lepton Flavour Violation (cLFV) process are highly suppressed in the Standard Model, even forbidden if neutrino mixing is not taken into account. Any observation of cLFV decay would be a clear hint of new Physics Beyond SM, since their expected branching fraction ($\mathcal{B}$) is well below any current experiment sensitivity. The LHCb collaboration has performed many searches of cLFV involving heavy hadrons in $b\to s l^+l^-$, $b\to c l^-\nu_l$ and $\tau$ decays, setting upper limits to constrain BSM theories.