I. Application of multi-Regge theory to production processes. II. High energy model for proton-proton scattering

This dissertation consists of two parts. The first part presents an explicit procedure for applying multi-Regge theory to production processes. As an illustrative example, the case of three body final states is developed in detail, both with respect to kinematics and multi-Regge dynamics. Next, the experimental consistency of the multi-Regge hypothesis is tested in a specific high energy reaction; the hypothesis is shown to provide a good qualitative fit to the data. In addition, the results demonstrate a severe suppression of double Pomeranchon exchange, and show the coupling of two "Reggeons" to an external particle to be strongly damped as the particle's mass increases. Finally, with the use of two body Regge parameters, order of magnitude estimates of the multi-Regge cross section for various reactions are given.

The second part presents a diffraction model for high energy proton-proton scattering. This model developed by Chou and Yang assumes high energy elastic scattering results from absorption of the incident wave into the many available inelastic channels, with the absorption proportional to the amount of interpenetrating hadronic matter. The assumption that the hadronic matter distribution is proportional to the charge distribution relates the scattering amplitude for pp scattering to the proton form factor. The Chou-Yang model with the empirical proton form factor as input is then applied to calculate a high energy, fixed momentum transfer limit for the scattering cross section, This limiting cross section exhibits the same "dip" or "break" structure indicated in present experiments, but falls significantly below them in magnitude. Finally, possible spin dependence is introduced through a weak spin-orbit type term which gives rather good agreement with pp polarization data.

High energy photoproduction of neutral mesons

Cross sections for the photoproduction of neutral pi, eta, rho and phi mesons on hydrogen have been measured at the Stanford Linear Accelerator Center using a missing mass spectrometer technique. The data cover photon energies between 5.0 and 17.8 GeV and four momentum transfer squared t between -.12 and -1.38 (GeV/c)².

Pion differential cross sections at lower energies show a peak at low momentum transfers, a distinctive dip and secondary maximum for t in the region -.4 to -.9 (GeV /c)², and a smooth decrease at higher momentum transfers. As photon energy increases, the dip becomes less pronounced, in contradiction to the expectations of simple Regge theories based on the exchange of omega and B trajectories only.

Eta photoproduction was measured only below 10 GeV. The cross section has about the same magnitude as the pion production cross section, but decreases exponentially with t, showing no dip.

Rho mesons appear to be diffractively produced. The differential cross section varies approximately as exp(8.5t + 2t²). It falls slowly with energy, decreasing about 35 percent from 6 GeV to 17.8 GeV. A simple quark model relation appears to describe the data well.

Phi meson cross sections are also consistent with diffraction production. The differential cross section varies approximately as exp(4t). The cross section tends to decrease slightly with photon energy.

Effects on the proton production from explosions of hydrogen clusters subjected to intense femtosecond laser fields

The dependence of the maximum and average energies of protons, which were produced in the interaction of an intense laser pulse (similar to 1 x 10(16) W cm(-2), 65 fs) with hydrogen clusters in a gas jet backed up to 80 bar at liquid nitrogen temperature (similar to 80 K), on the backing pressure has been studied. The general trend of the proton energy dependence on the square of the average cluster radius, which is determined by a calibrated Rayleigh scattering measurement, is similar to that described by theory under the single size approximation. Calculations are made to fit the experimental results under a simplified model by taking into account both a log-normal cluster size distribution and the laser intensity attenuation in the interaction volume. A very good agreement between the experimental proton energy spectra and the calculations is obtained in the high- energy part of the proton energy distributions, but a discrepancy of the fits is revealed in the low-energy part at higher backing pressures which are associated with denser flows. A possible mechanism which would be responsible for this discrepancy is discussed. Finally, from the fits, a variation of the cluster size distributions was revealed to be dependent on the gas backing pressure as well as on the evolving time of the gas flow of clusters.

Climate change impacts on the water services in Costa Rica: a production function for the hydroenergy sector

23 p.

Flavor SU(3) predictions for charmed baryon and B-meson decays

The predictions of the SU(3) flavor symmetry of the strong interactions for the weak decay of charmed baryons and B-mesons are detailed. It is hoped that comparison between these predictions and experiment will shed some light on the underlying dynamics involved in these weak decays. Although only a few decay modes of the charmed baryons and B-mesons have been studied experimentally it is hoped that the next generation of B-factories and even Z-decays at LEP will provide enough events to test these predictions.

Freshwater prawn fry production and delivery process: key to sustainable aquaculture development for Bangladesh

This study was conducted to identify a functioning fingerlings production and delivery system for a sustainable aquaculture development. Data were collected from 234 respondents randomly sampled from a population of 600 fish farmers. Results indicated that farmer-to-farmer was the major source of fingerlings production and distribution system. Although this source accessed disadvantaged groups like the rural based, resource poor, less educated and women, it lacked knowledge on how to produce good quality fingerlings. These results suggest that a decentralized and privatized fingerlings production and delivery system should be promoted. For this system to operate effectively the aquaculture department should first identify potential zones for aquaculture growth and profit motivated fingerlings producers and distributors. Furthermore, the institutional mechanism through which farmer-to-farmer will operate should be identified and strengthened through short and long term training programmes. The government should support the system by providing guidelines for good quality fingerlings management; maintain brood stock parents and technical training in Bangladesh.

Radiative tau production and decay

A study of the muon decay channel of the τ lepton with the presence of a photon has been carried out to verify theoretical predictions for the production rate of e⁺e^- → τ⁺τ^-γ and for the branching ratio of τ^- → ν_τ µ^-ν_µγ. Included in this study is the first direct measurement of radiative tau decay. Using e⁺e^- annihilation data taken at 29 GeV center-of-mass energy with the Mark II detector, we find the ratio of the measured τ^- → ν_τ µ^-ν_µγ branching fraction to the expected value from QED to be 1.03 ± 0.42. The ratio of measured-to-predicted number of events from radiative T production, e⁺e^- → τ⁺τ^-γ, where one of the τ's decay to μνν is found to be 0.91 ± 0.20. We have not seen an indication of anomalous behavior in radiative tau events.

Production of the chironomids of the Uchinsk Reservoir. [Translation of: Methods for the estimation of production of aquatic animals. (Handbook and papers) (ed. G. G. Vinberg) p226-239. Minsk, Vysheishaya Shkola, 1968]

The method of E.V. Borutski was used for determining the production of chironomids, that is, the dynamics of the number and biomass of the larvae were analysed, their death, a calculation of emergence and the number of deposited egg layings was carried out. In addition to the method of Borutski, the authors also calculated the seasonal dynamics of the number of larvae of the younger age stages in the microbenthos.