21234668
Comparison of bottom-quark production rates in ISAGET with a full QCD 2-->3 calculation.
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.
118886787
Massive Lepton Pair Production — the Drell-Yan Process — with Nuclear Targets
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.
118737822
Inclusive production of t {bar t} pairs in hadronic collisions
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.
14567671
Isolated prompt photon cross sections
We show that the conventionally defined partonic cross section for the production of isolated prompt photons is not an infrared safe quantity. We work out the case of {ital e}{sup +}{ital e}{sup -} {r_arrow} {gamma} + {Chi}, and discuss implications for hadron reactions.
123964038
Heavy flavor production at fixed target and collider energies
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.
120891008
CORRELATIONS IN HIGH-ENERGY PRODUCTION PROCESSES.
206321492
Hartree-Fock-Bogoliubov predictions for shape isomerism in nonfissile even-even nuclei.
Secondary minima in the potential-energy surfaces of even-even nuclei are searched for through nonaxial Hartree-Fock-Bogoliubov calculations based on a finite-range, density-dependent effective force. This study covering the mass region 64/lt//ital A//lt/208 is intended to select nonfissile nuclei which would develop shape isomers. Results are presented for nuclei which seem to be the most interesting candidates for experimental investigations.
41606550
Preliminary selection of candidates for shape isomerism from even-even nuclei with masses A<208.
This theoretical work represents the first stage in our efforts to establish an extensive list of nonfissile even-even nuclei located inside or near the valley of stability which might develop shape isomers. Our selection relies upon whether a secondary minimum takes place along an elongation axis in the potential energy surfaces of nuclei spread over the mass region A<208. These surfaces are determined through a joint use of the Hartree-Fock-Bogoliubov and Strutinsky methods. More than seventy nuclei located inside the region 40
31181789
Measurement of the B semileptonic branching fraction with lepton tags.
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 .
9151156
Effect of differences in proton and neutron density distributions on fission barriers
The neutron and proton density distributions obtained in constrained Hartree-Fock-Bogolyubov calculations with the Gogny force along the fission paths of 232Th, 236U, 238U, and 240Pu are analyzed. Significant differences in the multipole deformations of neutron and proton densities are found. The effect on potential energy surfaces and on barrier heights is studied under an additional constraint by imposing similar spatial distributions to neutrons and protons, as assumed in macroscopic-microscopic models.
45168751
Interaction of optical lasers with atomic nuclei.
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.