Measurements of the electroproduction reaction e-+ pe -AX' f n carried out at the Wilson Synchrotron Laboratory a r e reported. For fixed virtual photon-hadron center-of-mass energy, W=2.67 GeV, data are presented with the mass of the virtual photon, -k 2 , centered at 0.6, 1.2, and 2.0 G~v'. At the central -k 2 =1.2 (GeV)' point, results are also given for W =2.15 GeV. For the W =2.67, -k 2 = 1.2 Gev2 setting, an angular scan is presented and the longitudinal transverse-interference term is extracted. The data are compared with an electric Born-model calculation of Berends which has a s its only free parameter the pion electromagnetic form factor. The theory is used to extract new results for the pion form factor up to -k 2 =2.0 G~v'.

The total cross section for hadron production by high-energy photons has been measured from a number of nuclei ranging from hydrogen to uranium. Some shadowing is observed at a level considerably less than predicted by conventional vector-meson dominance but consistent with a modified theory. The energy dependence predicted by vectormeson dominance is observed. The shadowing in heavy nuclei shows a smooth transition from electroproduction to photoproduction.143.2± 2.7

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jB-meson decays to final states consisting of a D° or D* £ and one or two charged pions have been observed. The charged-B mass is 5270.8± 2.3 ±2.0 MeV and the neutral-E mass is 5274.2±1.9±2.0 MeV. PACS numbers: 14.40.Jz, 13.25.+m, 13.65. + iThe upsiion states 1 are interpreted as q-q resonances of a new quark, the b quark. The first three resonances are narrow, 2 ' 3 implying bound b flavor and a suppressed strong decay. The large width of the T(4S) resonance discovered at the e + e~ storage ring CESR 4 (Cornell Electron Storage Ring) and the observation that the decay products from the T(4S) include high-momentum leptons 5 imply that the T(4S) decays strongly into BB meson pairs, which then decay weakly. Until now, however, the b-flavored mesons themselves had not been found. Here we report that

An enhancement has been observed in the inclusive cross section for direct single electrons produced in e*e~ annihilations at the T(4S). This is interpreted as evidence for a new weakly decaying particle, the B meson. A branching ratio for B -Xev of ll3± 3 (±3)]% is inferred, where the first set of errors is statistical and the estimated systematic error is enclosed in parentheses.PACS numbers: 14.40.Pe, 13.20.Jf, 13.65.+ iThe recently discovered resonance in e*e~ annihilations at 10.55 GeV total energy 1 ' 2 has a natural interpretation as the T (4S) bound state of bfi quarks. Its width indicates that this state is above the threshold for producing pairs of B mesons, bound states of b quarks with u or i? quarks, and has as its dominant decay mode BB meson final states. 3 The existence of a new, weakly decaying flavor can be inferred from the semileptonic decay B-+Xlv and the branching ratio (BR) for this 84