Filters

Results

**1**-**10**of**2143** Results

**1**-**10**of**2143**. Search took:**0.03**secondsSort by: date | relevance |

Renger, B.S.L.

Carnegie-Mellon Univ., Pittsburgh, PA (USA)

Carnegie-Mellon Univ., Pittsburgh, PA (USA)

AbstractAbstract

[en] We have studied low-multiplicity hadronic decays of the Υ(9460) using 46 pb

^{-1}of data taken at the Crystal Ball detector at the DORIS II storage ring. In particular, hadronic final states of multiplicity 3, 4, 5, 6, and 7 containing only pions were considered. The 90% C.L. branching ratio upper limits on Υ → ρ^{0}π^{0}, ρ^{±}π^{minus-plus}, and ρπ are 7.7 x 10^{-4}, 5.1 x 10^{-3}, and 2.2 x 10^{-3}, respectively, and are consistent with previous results. We have also found 90% C.L. upper limits on Υ → π^{-}π^{-}π^{0}π^{0}π^{0}(1.6 x 10^{-3}), π^{-}π^{-}π^{-}π^{-}π^{0}(5.5 x 10^{-}), 5π (6.8 x 10^{-3}), ρπππ (8.1 x 10^{-3}), ρρπ (5.3 x 10^{-3}), and ρa_{2}(5.0 x 10^{-3}). All these latter results are first time results. Of the decays studied, the results for the two body final states are compared to theoretical predictions which are based on dimensional scaling laws and hadronic helicity conservation in QCD. A general formalism is presented for measuring the G-parity of the Υ. By applying it to the existing data sample we show that, at present, statistics is not sufficient to yield a conclusive resultPrimary Subject

Secondary Subject

Source

1987; 129 p; Carnegie-Mellon Univ; Pittsburgh, PA (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.88-02,942; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

Dunlea, J.M.

Ohio State Univ., Columbus, OH (USA)

Ohio State Univ., Columbus, OH (USA)

AbstractAbstract

[en] This work presents the first results of Fermilab Experiment 653, which was designed to study properties of particles containing charm or beauty produced by protons incident on emulsion. It describes in detail the apparatus of the experiment, which consisted of a hybrid emulsion spectrometer, and focuses on the Vertex Silicon Strip Detectors. Five million events were recorded on tape in the experiment's first run in 1985. A preliminary analysis yielded a D

^{±}peak with about 15 events above background, using only the electronic portion of the spectrometer and examining only the decay mode D^{±}→ K^{±}π^{±}π^{minus-plus}with 60% of the first run data. Events were selected on the basis of a set of cuts requiring good separation of the primary and secondary vertices and the balance of the momentum of the decay particles. The p_{T}^{2}and x_{F}distributions of the D^{±}candidates were examined; the p_{T}^{2}(after Monte Carlo efficiency corrections) agrees with other experiments; the s_{F}distributions seen is highly central with n in (1 - x_{F})^{n}having a value much greater than 4. The occurrence of a leading particle effect is also examined and none is seen within the low statistics of the experimentsPrimary Subject

Secondary Subject

Source

1987; 251 p; Ohio State Univ; Columbus, OH (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.88-04,031; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

AbstractAbstract

[en] The theoretical difficulty of identifying the radiative component of a general relativistic spacetime is manifested in numerical relativity as the problem of extracting asymptotic gravitational radiation waveforms at finite radii during simulations on spacelike slices. These waveforms can be contaminated by linear effects due to the choice of gauge and the wave's near zone field as well as by non-linear interactions. What is usually done is to extract the waveforms at large radii in the wave zone where these effects are assumed to be negligible using special radiative variables which have radiative terms rather than the mass monopole moment as the leading term in their asymptotic expansion. This approach can be wasteful of computer resources and is not very rigorous. We take a synergistic approach where a numerical solution of the Einstein equations coupled with hydrodynamics for the source and strong-field region is matched in the near zone or local wave zone onto a linear analytic solution used for the exterior region. No asymptotic flatness assumption is required; it is sufficient that the source be isolated enough that a local wave zone exists. These procedures are tested using simulated sinusoidal and non-sinusoidal pulsating neutron-star spacetimes. We demonstrate that each technique correctly matches the exterior and interior solutions to eliminate gauge effects and that the ODE integration separates off the near-zone field to yield asymptotic waveforms. We also present an application of these methods to Brill wave spacetimes. Discussion of non-linear effects in these spacetimes is also included

Primary Subject

Secondary Subject

Source

1988; 135 p; Univ. of Illinois; Urbana-Champaign, IL (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.89-08,603; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

Turner, R.E.

Ohio State Univ., Columbus (USA)

Ohio State Univ., Columbus (USA)

AbstractAbstract

[en] A search was made for fractional charges of the form Z plus two-thirds e, where Z is an integer. It was assumed that the charges exist in natural form bound with other fractional charges in neutral molecules. It was further assumed that these neutral molecules are present in air. Two concentration schemes were employed. One sample was derived from the waste gases from a xenon distillation plant. This assumes that high mass, low vapor pressure components of air are concentrated along with the xenon. The second sample involved ionizing air, allowing a brief recombination period, and then collecting residual ions on the surface of titanium discs. Both samples were analyzed at the University of Rochester in a system using a tandem Van de Graff to accelerate particles through an essentially electrostatic beam handling system. The detector system employed both a Time of Flight and an energy-sensitive gas ionization detector. In the most sensitive mode of analysis, a gas absorber was inserted in the beam path to block the intense background. The presence of an absorber limited the search to highly penetrating particles. Effectively, this limited the search to particles with low Z and masses greater than roughly fifty GeV. The final sensitivities attained were on the order of 1 x 10

^{-20}for the ionized air sample and 1 x 10^{-21}for the gas sample. A discussion of the caveats that could reduce the actual level of sensitivity is includedPrimary Subject

Secondary Subject

Source

1984; 114 p; University Microfilms Order No. 85-04,092; Thesis (Ph. D.).

Record Type

Report

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

Baerring, O.

Lund Univ. (Sweden). Dept. of Physics

Lund Univ. (Sweden). Dept. of Physics

AbstractAbstract

[en] In this thesis a fast and accurate method for the calculations of the energy loss spectrum is presented. The algorithm, which is based on the Laplace transform method, differs from earlier approaches in that it makes use of fast fourier transform routines instead of numerical integration or series expansion. We present also a new type of jet classification, based on artificial neural network technique. The classification is proved to be insensitive to the jet energy, i.e. it exploits only the fragmentation differences between quarks and gluons. We apply this method in a measurement of the triple-gluon vertex in four-jet events at LEP. (au) (33 refs.)

Primary Subject

Source

Sep 1992; 46 p; Doctoral dissertation (FD).

Record Type

Report

Literature Type

Thesis/Dissertation; Numerical Data

Report Number

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

Chambers, J.

London Univ. (United Kingdom)

London Univ. (United Kingdom)

AbstractAbstract

[en] This thesis describes a precision measurement of the mass of the D

^{0}meson using the decay D*^{+}→ π_{s}^{+}+ D^{0}(→ K^{-}π^{+}). The analysis is based on data taken using the using the ALEPH detector at CERN during the years 1992 - 1995 inclusive. The bulk of the work comprises a calibration for systematic measurement effects associated with ALEPH. These include ionisation energy loss, magnetic field calibration and subdetector misalignments each of which can affect measured mass. The D^{0}mass is measured to be 1.86479 ± 0.00033 GeV, consistent with and significantly more precise than the current world average, 1.8641 ± 0.0010 GeV. (author)Primary Subject

Source

1998; [vp.]; Available from British Library Document Supply Centre- DSC:DXN038606; Thesis (Ph.D.)

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

Keller, C.M.

North Dakota State Univ., Fargo, ND (USA)

North Dakota State Univ., Fargo, ND (USA)

AbstractAbstract

[en] In order to understand a many-body liquid Bose system one must first determine the ground-state (absolute zero temperature) and the equilibrium density. In theory one need only solve the Schroedinger equation for the N-body system to determine these properties. In practice, however, the Schroedinger equation is exactly soluble for every few instances, mostly low-dimensionally and/or with simplistic interactions. Therefore, some approximations must be used. Many theoretical approaches, both perturbative and variational, have been applied to the liquid Bose system. Here we employ a perturbative approach, which is based not on the ideal gas as a reference unperturbed state but on the corresponding nontrivial fluid of repulsive particles. We begin with the non-analytic (i.e., non-power) series in the density and coupling obtained through infinite partial summation renormalization techniques for the energy-per-particle. Only the first three coefficients of this series have been determined and the series is initially valid only at small densities and weak coupling values. The original series is rearranged to become a power series in a coupling parameter of the attraction alone, with coefficients which are still non-power series in the density. The later series is extrapolated to higher (i.e., physical) densities with generalized Pade approximants. Standard Pade analyses are applied to the attractive coupling series. Good to excellent results are obtained for several intermolecular potentials in comparison with available computer simulations which essentially give exact results

Primary Subject

Secondary Subject

Source

1988; 118 p; North Dakota State Univ of Agriculture and Applied Science; Fargo, ND (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.88-25,875; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

Mitchell, J.W.

Ohio State Univ., Columbus, OH (USA)

Ohio State Univ., Columbus, OH (USA)

AbstractAbstract

[en] This document describes a neutrino oscillation experiment performed at the Los Alamos Meson Physics Facility. The oscillation model searched for is bar ν

_{μ}→ bar ν_{e}. The first chapter is a review of the known properties of the neutrino and a description of the phenomenon of neutrino oscillation. Previous experimental limits on this unobserved phenomenon are also given. The second chapter describes the experimental apparatus used by the E645 experiment to detect neutrinos produced in the LAMPF beam stop. The salient features of the detector are its large mass (20 tons of CH_{2}), its fine segmentation (to allow good particle tracking), good energy resolution, its recording of the history both before and after tracks appear in the detector, an active cosmic-ray anticoincidence shield, and 2000 gm/cm^{2}of passive cosmic-ray shielding. It is located 26.8 m from the neutrino source, which has a mean neutrino energy of 40 MeV. The third chapter details the reduction of the 1,3 million event data sample to a 49 event sample of neutrino candidates. Principle backgrounds are Michel electrons from stopping cosmic-ray muons and protons from np elastic scattering by cosmic-ray neutrons. The fourth chapter explains how background levels from neutrino-nuclear scattering are predicted. The result of maximum-likelihood analysis reveals no evidence for oscillation. 90% confidence levels are set at δm^{2}= .10 eV^{2}for large mixing and sin^{2}(2θ) = .014 for large δm^{2}Primary Subject

Secondary Subject

Source

1989; 244 p; Ohio State Univ; Columbus, OH (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.89-13,680; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

AbstractAbstract

[en] In this dissertation we study a procedure which restarts a Markov process when the process is killed by some arbitrary multiplicative functional. The regenerative nature of this revival procedure is characterized through a Markov renewal equation. An interesting duality between the revival procedure and the classical killing operation is found. Under the condition that the multiplicative functional possesses an intensity, the generators of the revival process can be written down explicitly. An intimate connection is also found between the perturbation of the sample path of a Markov process and the perturbation of a generator (in Kato's sense). The applications of the theory include the study of the processes like piecewise-deterministic Markov process, virtual waiting time process and the first entrance decomposition (taboo probability)

Primary Subject

Secondary Subject

Source

1988; 88 p; Univ. of Maryland; College Park, MD (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.88-18,371; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

Fertig, H.A.

Harvard Univ., Boston, MA (USA)

Harvard Univ., Boston, MA (USA)

AbstractAbstract

[en] In this thesis, we examine some properties of electrons that are confined to a two-dimensional surface and are subject to a magnetic field applied perpendicular to the plane. Chapter 2 is a detailed study of the hypernetted chain (HNC) approximation and its application to the analysis of trial wave functions for the fractional quantized Hall effect. We compare our electron-electron pair correlation function of the quasielectron state with that generated by the Laughlin pseudopotential approximation. We find that our result is qualitatively in better agreement with the results for a finite number of particles on a sphere. In Chapter 3, we compute the transmission coefficient for an electron to tunnel through a purely quadratic saddle point potential. This quantity may be computed without approximation, and has a surprising simple form. In Chapter 4, we study the effects of tunneling on an electron in a strong perpendicular magnetic field and an external potential that varies slowly in space. We discuss in detail the case of a double well potential separated by a single saddle point. We find that tunneling effects are only important when the classical orbits pass within a few magnetic lengths of the saddle point

Primary Subject

Secondary Subject

Source

1988; 218 p; Harvard Univ; Cambridge, MA (USA); University Microfilms, PO Box 1764, Ann Arbor, MI 48106, Order No.89-01,567; Thesis (Ph. D.).

Record Type

Miscellaneous

Literature Type

Thesis/Dissertation; Numerical Data

Country of publication

Publication YearPublication Year

Reference NumberReference Number

INIS VolumeINIS Volume

INIS IssueINIS Issue

1 | 2 | 3 | Next |