Breakdown of conventional factorization for isolated photon cross sections.
Using {ital e{sup +}e{sup -} {r_arrow} {gamma} + X} as an example, we show that the conventional factorization theorem of perturbative QCD breaks down for isolated photon cross sections in a specific part of phase space. Implications are discussed.

title: Inclusive production of t {bar t} pairs in hadronic collisions
abstract: We summarize our calculation of the total cross section for top quark production at hadron colliders within the context of perturbative quantum chromodynamics, including resummation of the effects of initial-state soft gluon radiation to all orders in the strong coupling strength.

title: Heavy flavor production at fixed target and collider energies
abstract: A review is presented of heavy quark production in /bar p/p, p, and pp interactions at fixed target and collider energies. Calculations of total cross sections are described including contributions through next-to-leading order in QCD perturbation theory. Comparisons with available data on charm and bottom quark production show good agreement for reasonable values of charm and bottom quark masses and other parameters. Open issues in the interpretation of results are summarized. A discussion is presented of signatures, backgrounds, and expected event rates for top quark production. 19 refs., 4 figs.

title: Massive Lepton Pair Production — the Drell-Yan Process — with Nuclear Targets
abstract: The Drell-Yan process, hA → (μμ-)X, in which a massive lepton-pair is produced inclusively from a nuclear target, offers the possibility for gaining unique insight into the A dependence of the quark and antiquark densities of nuclei, qA(x,Q2) and q-A(x,Q2). Measurements are crucial for testing whether the A dependence of deep-inelastic structure functions, known as the EMC effect, is a universal, process independent property of parton densities. Precise experiments with pion and nucleon beams on nuclear targets would extend knowledge of the A dependence of quark and antiquark densities of nuclei into important intervals of the fractional longitudinal momentum variable x which are not accessible easily in deep inelastic scattering. Models constructed to interpret the EMC effect are used to obtain predictions for the A dependence of massive lepton pair production. For tests of quantum chromodynamics, isolating nuclear dependence is necessary before definite conclusions can be drawn on the behavior of the pion structure function and on the magnitude and kinematic variation of predicted higher order terms (K factor). I indicate the sensitive regions of phase space and the increased level of experimental precision which is needed if a contribution is to be made to isolating the A dependence of quark and antiquark densities from the Drell-Yan process.

title: CORRELATIONS IN HIGH-ENERGY PRODUCTION PROCESSES.

title: Comparison of bottom-quark production rates in ISAGET with a full QCD 2-->3 calculation.
abstract: High-statistics samples of events have been generated with the ISAGET Monte Carlo simulation program in a study of bottom-quark production in proton-antiproton collisions at {radical}{ital s} =630 and 1800 GeV. These samples include lowest-order QCD production, flavor excitation, and gluon splitting contributions. Both Eichten-Hinchliffe-Lane-Quigg and Diemoz-Ferroni-Longo-Martinelli structure functions have been used. The integral transverse-momentum distribution {sigma}{sub {ital T}}({ital p}{sub {ital T},}{ital b}{gt}{ital p}{sub {ital T},min}) is presented for each data set. Results are compared to a full analytical next-to-leading-order calculation of Nason, Dawson, and Ellis. We find that ISAGET cross sections at large {ital p}{sub {ital T}} are greater than the results obtained in the analytical calculation. In addition, the ratio of the full cross section to the lowest-order result ({ital K} factor) can be as large as a factor of 2 greater than the analytical result, depending on {radical}{ital s} and {ital p}{sub {ital T}}. We discuss the implications of these overestimates that relate to the phenomenology of heavy-flavor production, notably searches for the top quark.

title: Measurement of the B semileptonic branching fraction with lepton tags.
abstract: We have used the CLEO II detector and 2.06fb^(-1) of ϒ(4S) data to measure the B-meson semileptonic branching fraction. The B→Xeν momentum spectrum was obtained over nearly the full momentum range by using charge and kinematic correlations in events with a high-momentum lepton tag and an additional electron. We find B(B→Xeν) = (10.49±0.17±0.43)%, with overall systematic uncertainties less than those of untagged single-lepton measurements. We use this result to calculate the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element V_(cb) and to set an upper limit on the fraction of ϒ(4S) decays to final states other than BB .

title: Interaction of optical lasers with atomic nuclei.
abstract: Nuclear transitions induced by an optical laser coupled to atomic electrons are examined in the context of a soluble model obtained by replacing the Coulomb field of the electrons by a harmonic oscillator. The results indicate that present lasers are marginal for causing this effect, but reasonable extrapolations in intensity and frequency would lead to experimental tests. Choosing the oscillator constant to reproduce realistic atomic radii results in nuclear electric dipole transitions that are potentially observable but that higher electric moments will be too small.

title: Search for exclusive charmless hadronic B decays.
abstract: We have searched for two-body charmless hadronic decays of B mesons. Final states include ππ, Kπ, and KK with both charged and neutral kaons and pions: πρ, Kρ, and K^*π; and Kφ, K^*φ, and φφ. The data used in this analysis consist of 2.6×10^6 BB¯ pairs produced at the Υ(4S) taken with the CLEO II detector at the Cornell Electron Storage Ring (CESR). We measure the branching fraction of the sum of B^0→π^+π^- and B^0→K^+π^- to be (1.8_(-0.5-0.3)^(+0.6+0.2)±0.2)×10^(-5). In addition, we place upper limts on individual branching fractions in the range from 10^(-4) to 10^(-6).

title: Limits on flavor changing neutral currents in D0 meson decays.
abstract: Using the CLEO II detector at the Cornell Electron Storage Ring, we have searched for flavor changing neutral currents and lepton family number violations in D^0 meson decays. The upper limits on the branching fractions for D^0→l^+l^- and D^0→X^0l^+l^- are in the range 10^(-5) to 10^(-4), where X^0 can be a π^0, K_s^0, η, ρ^0, ω, K^(*0), or φ meson, and the l^+l^- pair can be e^+e^-, μ^+μ^-, or e^±μ^∓. Although these limits are above the theoretical predictions, most are new or an order of magnitude lower than previous limits.

title: Mean-field description of ground-state properties of drip-line nuclei: Pairing and continuum effects.
abstract: Ground-state properties of exotic even-even nuclei with extreme neutron-to-proton ratios are described in the framework of self-consistent mean-field theory with pairing formulated in coordinate space. This theory properly accounts for the influence of the particle continuum, which is particularly important for weakly bound systems. The pairing properties of nuclei far from stability are studied with several interactions emphasizing different aspects, such as the range and density dependence of the effective interaction. Measurable consequences of spatially extended pairing fields are presented, and the sensitivity of the theoretical predictions to model details is discussed.