Browsing by Author "Mengesha, Elias"

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    Studies on Pion Compton Scattering and Pion Elelectroproduction in the Framework of Scalar Electrodynamics
    (Addis Ababa University, 2001-06) Mengesha, Elias; Bhatnagar, Shashank (PhD)
    In this thesis we first discuss the S-matrix expansion in the interaction representation. Vve employ this to illustrate the calculational techniques in the study of one of the QED processes-i.e., electron Compton scattering. "Ve then formulate Scalar Electrodynamics which is the relativistic theory for the interaction of scalar particles (such as 1fo,1f±) with the electromagnetic fields A", In this process we work out the mathematical forms of the pion propagator. ~We then use Scalar Electrodynamics to study the processes such as pion Compton scattering and pion Electroproduction. "Ve give explicit evaluation of the transition amplitudes and the scattering cross sections for both these processes. 'Ve then compare the pion Compton scattering results with the corresponding results for the electron Compton scattering
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    Treatment of Some High and Low Energy Hadronic Transitions in the Framework of Bethe-Salpeter Dynamical Programme for a Composite Hadron
    (Addis Ababa University, 2014-02) Mengesha, Elias; Shashank, S. Bhatnagar (PhD)
    In this thesis we employ Bethe Salpeter Equation(BSE) under Covariant Instanta- neous Ansatz(CIA) to calculate: (A) The cross section of double Charmonium pro- duction from electron-positron annihilation at the CM energy 10:6GeV through the process e++e􀀀 ! J= + c, which has recently been observed at B factories and whose measurements were done by Babar and Belle groups. (B) The decay width for the ra- diative decay of equal mass vector mesons through the process h ! h0 + (h=vector meson, h'=pseudoscalar meson and =the emitted photon.) (C) Decay width for strong decay of excited vector mesons through the process h ! h0 + h"(h=excited vector meson, h'=vector meson and h"=pseudoscalar meson.) The calculated results are in reasonable agreement with data