Lepton Flavour Universality tests with heavy flavour decays at LHCb

Several recent measurements of semileptonic charged-current and neutral-current B decays differ somewhat from theoretical predictions. While none of the individual measurements is statistically compelling, taken together they present a picture that hints to possible signs of new physics. An updated measurement of $R_K$ ≡ $\frac{BF (B^+ \rightarrow K^+ \mu^+ \mu^-)} {BF (B^+ \rightarrow K^+ e^+ e^-)}$ is presented, based on a combination of 3 fb$^{-1}$ of LHCb Run 1 data and 2 fb$^{-1}$ of Run 2 data. For the dilepton invariant mass range 1.1 ≤ q$^2$ ≤ 6.0 GeV$^2$ , we measure $R_K$ = 0.846 $^{+0.060+0.016} _{-0.054-0.014}$ , where the first uncertainty is statistical and the second systematic. This measurement is consistent with the Standard Model prediction of $R_K$ = 1.0 at the level of 2.5σ.