Semileptonic B Meson Decays

Semileptonic decays of B mesons play a critical role in the determination of the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements Vcb and Vub. These two quantities are fundamental parameters of the Standard Model and have to be determined experimentally. Over the past decade, the vast samples of B mesons recorded at the B factories at LEP at Cornell University, KEK at Tsukuba, and SLAC at Stanford University have allowed for detailed studies of semileptonic B decays. These decays proceed via first-order weak interactions; thus, they are expected to be free of non–Standard Model contributions and therefore are well suited for the extraction of the quark-mixing parameters. Differential decay rates are combined with theoretical calculations of hadronization effects, leading to a substantially improved knowledge of |Vcb| and |Vub|. The results are used to constrain the parameters of the CKM matrix and to test the Standard Model predictions for CP-violating effects.