Document Details
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Document Type |
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Thesis |
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Document Title |
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Weak interactions of Neutrinos with free Nucleons at high Energies التفاعلات الضعيفة للنيوترينو مع النيوكلونات الحرة عند الطاقات العالية |
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Subject |
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Weak interactions of Neutrinos with free Nucleons at high Energies |
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Document Language |
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Arabic |
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Abstract |
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المستخلص انجليزي The neutrino plays a very important role in the world of particle and astrophysics. It has enormous penetration properties and gives us a unique and powerful possibility to investigate the internal structure of the nucleon and the internal invisible region of the sun where solar energy is produced etc.
The neutrinos are exceptional particles as for their intrinsic properties. The Neutrino's mass is many orders of magnitude smaller than the masses of their family partners (electron, muon, tau). Because of the smallness of the neutrion masses new physical phenomenon, such as neutrino oscillations are discovered. The investigation of the neutrino oscillations that is going on all over the world is a new field of research in particle and astrophysics. These important properties of the neutrino had encouraged us to get insight and pursue the feature of the neutrino's interactions. Here we presented two different models that may throw the light and declare the mysteries of the neutrino's behavior.
The first one (A phenomenological model): The particles production at high-energy neutrino- nucleon collisions is one of the most important features of such reactions. It carries more information about the fields working between quarks, which are assumed due to the exchange of gluons. We used the analysis of the data of the experiment CERN-WA-025 at neutrino energy less than 260GeV and the experiments FNAL-616 and FNAL-701 at energy range 120-250 GeV that shows that the structure functions F2 and x F3 are approximately independent on the momentum transfer square Q2, but instead depend on the Bjorken scalar variable x. The general features of these experiments are used as a base to build a hypothetical model that views the reaction by a Feynman diagram of two vertices. The first of which concerns the weak interaction between the neutrino and the quark constituents of the nucleon. At the second vertex, a strong color field is assumed to play the role of particle production, which depends on the momentum transferred from the first vertex and exchanges a heavy noson W or Z. The first vertex is considered as the source, which supplies the second vertex with energy that is used to create pairs of hadrons through strong interaction. The rate of energy transferred is controlled by the matrix element of weak interaction at the first vertex.
The target nucleon is described in terms of the quark wave functions that depend on quantum numbers concerning the quarks (momentum, spin, color and flavor). The wave functions of the nucleon quarks are determined using the variation method and relevant boundary conditions are applied to calculate the deep inelastic cross sections of the virtual diagram.
The values of these parameters are determined to minimize the total energy of the quark system of the nucleon. It is found that the ground state E0 has a line symmetry about x= 0.5. the symmetry breaks at the higher-up states, where the probability increases towards the deep inelastic x < 0.5.
The average values of multiplicity distributions of secondary hadrons are calculated according to the predictions of the model at incident v-energies of 2, 8, 22 and 146 GeV, The comparison with the experimental data shows very good agreement.
The wave functions of the quarks forming the nucleon are als determined by another technique based on the Lattice gauge theory. It assumes that the quarks are arranged inside the nucleon in the form of lattice structure. The Hartree Fock method is applied to calculate the wave function of the composite nucleon system.
In the second model we assumed that the neutrino interacts with nucleons through the IVB which may be the W or Z with effective mass about 80 GeV, in a similar way as the electromagnetic ones do, by photon exchange. The reaction is represented by a Feynman diagram to calculate the total interaction matrix element. It is described in terms of:
• The boson propagator which is associated to the process and has the form ….
• The leptonic current and the hadronic or the quark current.
We calculated the leptonic current at the first vertex by consider the neutrino's wave function as a plane wave but we used the perturbation technique to find the scattered wave function, where the neutrino has only a negative helicity state (left-handed component). Since the scattering is assumed due to a weak field, then it is sufficient to consider only the first term in the perturbation series. The weak leptonic current density is a complex function of the momentum transfer q, the imaginary part of which represents the rate of absorption in the reaction.
The data of the experiments that are extracted from the deep inelastic scattering of neutrion with nucleon [CERN-WA-025,CERN-WA-059, and FNAL-616], are used to put the functions F2 and x F3 in parametric forms in the variable x, consequently, the quark functions d, u, d and ū are calculated using the approximation of setting the Cabibbo angle to zero. The wave functions of the quarks and the antiquarks are estimated by the empirical method. It is found that the weak hadronic current depends mainly on the Bjorken variable and almost independent of Q2. The prediction of the models shows global fair agreement with experimental data in the energy range 120-250 GeV. |
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Supervisor |
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dr.mohammed tareg zakareya |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1424 AH
2003 AD |
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Added Date |
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Monday, December 29, 2014 |
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Researchers
| وداد ريف الحربي | alharbi, wadaad reef | Investigator | Doctorate | |
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