A search for the rare decay B -> pi l⁺l⁻

This thesis presents a search for the rare B meson decay B -> pi l⁺l⁻ (l=e or mu) using 428 fb⁻¹ of data collected at the Upsilon(4S) resonance by the BaBar detector at the PEP-II asymmetric energy e⁺e⁻ storage rings located located at SLAC National Accelerator Laboratory in Menlo Park, California. Four exclusive modes are studied: B⁺ -> pi+ e⁺e⁻, B⁺ -> pi⁺ mu⁺mu⁻, B0 -> pi⁰ e⁺e⁻, and B0 -> pi⁰ mu⁺mu⁻. Branching fraction upper limits at the 90% confidence level are presented for the exclusive modes B⁺ -> pi⁺ mu⁺mu⁻ and B0 -> pi0 mu⁺mu⁻, and the combined mode B -> pi mu⁺mu⁻.