APPLICATION OF ELECTROWEAK THEORY TO NEUTRINO-INDUCED SIGMA-LAMBDA HYPERONS TRANSITIONS

Abstract

this thesis, the electroweak description of neutrino-induced neutral weak transition between Sigma and Lambda hyperons is present. The norm-squared invariant element has been manipulated into a contraction between leptonic and hyperon tensors. The Electroweak (GWS) theory is used to calculate the leptonic tensor exactly. However, the hadronic tensor involves a vertex not fully understood by the electroweak theory due to the fact that hyperons are composite particles. As such, hadronic vertex is parameterized by three unknown form factors to account for the effects of strong intersection. Then the unknown form factors are determined in the framework of Cabibbo V-A theory and SU (3) symmetry. In addition, in the Laboratory (Lab) frame where the target Sigma hyperon is at rest, the kinematics and dynamics of the scattering process have been evaluated, separately. The Feynman rules, Casimir’s trick and trace theorems have been employed in constructing the relativistic expression of spin-average invariant-amplitude. Upon integrating over the Dirac delta function, the differential cross section (DCS) turns into a computationally feasible expression. The numerical results of the DCS have been generated by using Matlab R2016a programming language. The results show that for fixed scattering angle increasing the incident energy will increase the differential cross-section (DCS) and hence the angular distribution is found to be forward-peaked. However, by simply lowering the incident neutrino energy it is possible to enhance the contribution of backward scatterings as they begin to exhibit a non-vanishing contribution to the angular distribution. Moreover, the energy distributions reveal that the peak of the DCS occurs in the intermediate energy region, which implies that the study of deep inelastic scattering at high incident energies with minimal interference of elastic and quasielastic processes becomes a possibility