W. N. Cottingham

e + e − Annihilation

In recent years the development of electron-positron colliding beam facilities with high energies and intensities has opened a fascinating new window on particle structure. To date most attention has focused on electron-positron annihilation through the one-photon process, and it is with this aspect of e + e − collisions that we shall be primarily concerned.

Study of B→π ν and B→ρ ν decays and determination of

We present an analysis of exclusive charmless semileptonic B-meson decays based on 83×106 BB pairs recorded with the BABAR detector at the Υ(4S) resonance. Using isospin symmetry, we measure branching fractions B(B0→π- +ν)=(1.38±0.10±0.16±0.08)×10-4 and B(B0→ρ- +ν)=(2.14±0.21±0.48±0.28)×10-4, where the errors are statistical, experimental systematic, and due to form-factor shape uncertainties. We compare the measured distribution in q2, the momentum-transfer squared, with theoretical predictions for the form factors from lattice QCD and light-cone sum rules, and extract the Cabibbo-Kobayashi- Maskawa (CKM) matrix element |Vub|=(3.82±0.14±0.22±0.11-0. 52+0.88)×10-3 from B→π ν, where the fourth error reflects the uncertainty of the form-factor normalization.