Searches for flavour-changing neutral current processes at the BaBar experiment

Flavour changing neutral current process, such as B → K^(∗)l⁺l⁻ where l = e⁺,μ⁺,τ⁺ or ν_l, are highly suppressed in the Standard Model (SM) with a branching fraction ranging between 10⁻⁵ and 10⁻⁷. These rare decays are forbidden at tree level and can only occur at lowest order via 1-loop diagrams. B → K^(∗)l⁺l⁻ provides a stringent test of the SM and a fertile ground for new physics searches. Contributions due to virtual particles in the loop allow one to probe, at relatively low energies, new physics at large mass scales. The BABAR experiment at the SLAC National Accelerator Laboratory has completed data taking, with 424 fb⁻¹ collected at the Υ(4S) resonance. Using data from the BABAR experiment, I report the search for B → K^(∗)νν and its extension to charmonium resonance B → K^(∗)cc, cc → νν. BABAR’s results for B → K^(∗)l⁺l⁻ with l = e⁺ or μ⁺ are also discussed. Furthermore, the ongoing first search for B⁺ → K⁺ τ⁺τ⁻ is presented, along with its current status and anticipated sensitivity.