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Articles 31 - 43 of 43
Full-Text Articles in Elementary Particles and Fields and String Theory
Exclusive Π- Electro-Production From The Neutron In The Resonance Region, Jixie Zhang
Exclusive Π- Electro-Production From The Neutron In The Resonance Region, Jixie Zhang
Physics Theses & Dissertations
The study of baryon resonances is crucial to our understanding of nucleon structure. Although the excited states of the proton have been studied in great detail, there are very few data available for the neutron resonances because of the difficulty inherent in obtaining a free neutron target. To overcome this limitation, the spectator tagging technique was used in one of the CEBAF Large Acceptance Spectrometer (CLAS) collaboration experiments, Barely off-shell Nuclear Structure (BoNuS), in Hall-B at Jefferson Lab. We have constructed a radial time projection chamber (RTPC) based on the gaseous electron multiplier (GEM) technology to detect low momentum …
Spin Structure Of The Deuteron, Nevzat Guler
Spin Structure Of The Deuteron, Nevzat Guler
Physics Theses & Dissertations
Double spin asymmetries for the proton and the deuteron have been measured in the EG1b experiment using the CLAS detector at Jefferson Lab. Longitudinally polarized electrons at energies 1.6, 2.5, 4.2 and 5.7 GeV were scattered from longitudinally polarized NH3 and ND3 targets. The double spin asymmetry A|| for the proton and the deuteron has been extracted from these data as a function of W and Q2 with unprecedented precision. The virtual photon asymmetry A1 and the spin structure function g1 can be calculated from these measurements by using parametrization to the world data for the virtual …
Measurements Of Correlated Pair Momentum Distributions In -3he(E,E',P,P)N With Clas, Hovhannes Baghdasaryan
Measurements Of Correlated Pair Momentum Distributions In -3he(E,E',P,P)N With Clas, Hovhannes Baghdasaryan
Physics Theses & Dissertations
Nucleon-Nucleon (NN) Short Range Correlations (SRC) represent a valuable part of the nuclear wave function. Improved knowledge of SRC will give us a better understanding of nuclear matter and nuclear interactions in extreme conditions. A study of the effects of short-range correlations using the 3He(e, e'pp)n reaction measured at Jefferson Lab is presented. Two different approaches were selected to investigate SRC. The first approach consists of the kinematics when we investigate the two active protons and neutron is the spectator (was not involved in the interaction). This kinematics dominates by Final State Interactions which are reasonably …
Running Coupling Constant And Transition From Low To High Energies In Quantum Chromodynamics, Alexander Babansky
Running Coupling Constant And Transition From Low To High Energies In Quantum Chromodynamics, Alexander Babansky
Physics Theses & Dissertations
The remarkable feature of QCD is that the coupling constant (the strength of the interaction) depends on the energy of the interacting particles. At high energies, the coupling constant vanishes and QCD becomes asymptotically free. However, at lower energy, the running coupling constant increases, leading to the confining strong-coupling theory at energies of the order of hadron masses. We study the essential effects of the running coupling constant and analyze the transition from high to low energies in different processes.
The ²H(E, E'P)N Reaction At High Four-Momentum Transfer, Hassan F. Ibrahim
The ²H(E, E'P)N Reaction At High Four-Momentum Transfer, Hassan F. Ibrahim
Physics Theses & Dissertations
This dissertation presents the highest four-momentum transfer, Q2, quasielastic (xBj = 1) results from Experiment E01-020 which systematically explored the 2H(e, e'p)n reaction ("Electro-disintegration" of the deuteron) at three different four-momentum transfers, Q2 = 0.8, 2.1, and 3.5 GeV2 and missing momenta, pmiss = 0, 100, 200, 300, 400, and 500 GeV including separations of the longitudinal-transverse interference response function, RLT, and extraction of the longitudinal-transverse asymmetry, ALT. This systematic approach will help to understand the reaction mechanism and the deuteron structure down to the short …
Inclusive And Exclusive Compton Processes In Quantum Chromodynamics, A. Psaker
Inclusive And Exclusive Compton Processes In Quantum Chromodynamics, A. Psaker
Physics Theses & Dissertations
In our work, we describe two types of Compton processes. As an example of an inclusive process, we consider the high-energy photoproduction of massive muon pairs off the nucleon. We analyze the process in the framework of the QCD parton model, in which the usual parton distributions emerge as a tool to describe the nucleon in terms of quark and gluonic degrees of freedom. To study its exclusive version, a new class of phenomenological functions is required, namely, generalized parton distributions. They can be considered as a generalization of the usual parton distributions measured in deeply inelastic lepton-nucleon scattering. Generalized …
Some Aspects Of Deeply Virtual Compton Scattering, Elena Kuchina
Some Aspects Of Deeply Virtual Compton Scattering, Elena Kuchina
Physics Theses & Dissertations
We consider different aspects of the virtual Compton amplitude in QCD on two examples: small-x physics accessible in the Regge regime and twist-3 approximation in the description of DVCS through the general parton distributions. Using this model, we give an estimate for the cross section of deeply virtual Compton scattering for the kinematics of CEBAF at Jefferson Lab.
Generalized Compton Amplitudes In Quantum Chromodynamics, Ignati Grigentch
Generalized Compton Amplitudes In Quantum Chromodynamics, Ignati Grigentch
Physics Theses & Dissertations
In this dissertation we describe results of our studies of generalized Compton amplitudes. We have calculated the one-loop corrections to the amplitude in the coordinate representation in terms of nonlocal string light-ray operators. We have also developed a consistent approach to the problem of constructing the gauge invariant Compton amplitude and obtained an expression for the explicitly gauge invariant amplitude which includes all the generalized target-mass corrections.
Precision Measurement Of The Spin Structure Of The Proton And The Deuteron, Frank R. Wesselmann
Precision Measurement Of The Spin Structure Of The Proton And The Deuteron, Frank R. Wesselmann
Physics Theses & Dissertations
Experiment E155 at the Stanford Linear Accelerator Center measured the spin structure functions g1 and g2 of the proton and deuteron using deep inelastic scattering of 50 GeV polarized electrons from dynamically polarized, solid 15NH3 and 6LiD targets. Three independent spectrometers, covering a large kinematic region, 0.014 < xBjorken < 0.9 and 1 < Q2 < 40 (GeV /c)2, detected 200 million events. A fully self-consistent and statistically sound approach to calculating radiative corrections was developed, providing well-defined statistical errors for the E155 data set. Also, a comprehensive fit to the global data set was created which simultaneously …
Virtual Compton Scattering Processes In Quantum Chromodynamics, Igor V. Musatov
Virtual Compton Scattering Processes In Quantum Chromodynamics, Igor V. Musatov
Physics Theses & Dissertations
Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive meson electroproduction processes require a generalization of usual Parton distributions for the case when long-distance information is accumulated in nonforward matrix elements [special characters omitted] of quark and gluon light-cone operators. We consider different aspects of the investigation of the virtual Compton amplitude in the QCD on two examples: the spin dependent observables in the forward virtual Compton process (measured in the experiments on deep inelastic scattering) and the γγ* transition form factor. Then we discuss in detail evolution equations for non-forward parton distributions [special characters omitted] The …
The Use Of Operator Regularization In The Computation Of Effective Field Theories, Jeffrey M. Hersh
The Use Of Operator Regularization In The Computation Of Effective Field Theories, Jeffrey M. Hersh
Physics Theses & Dissertations
Current methods of computing low-energy effective field theories while being accurate are extremely cumbersome co implement. Operator regularization provides a way to calculate any desired effective field theory avoiding the tediousness of previous methods. This technique is shown to be an effective method in explicitly calculating the 1/mheavy corrections that match an original full theory to its low-energy effective counterpart. This is demonstrated up to two loop order for the case of a charged two field θ{4}{4} theory as well as up to one loop order for the Higgs sector of the Minimal Supersymmetric Model. Additionally, the renormalization …
A Relativistic Model For Heavy Mesons, Jialin Zeng
A Relativistic Model For Heavy Mesons, Jialin Zeng
Physics Theses & Dissertations
Motivated by the present interest in the heavy quark effective theory, we construct a model for heavy mesons based on a relativistic bound state wave equation, the Gross equation. The kernel we use is based on scalar confining and vector Coulomb potentials. Wave functions are treated to leading order and energies to order 1/MQ in the heavy-light systems, and to order 1/M2Q in heavy-heavy systems. Our results are in good agreement with experimental measurements. This model may be used to study weak decay properties in the framework of the heavy quark effective theory and ultimately to …
Excitation Of Hydrogen Atoms By Fast Protons, Edward Ellis Fitchard
Excitation Of Hydrogen Atoms By Fast Protons, Edward Ellis Fitchard
Physics Theses & Dissertations
In this thesis a theoretical study is made of excitation of hydrogenic atom by charged particles such as protons or electrons. The approximation to the cross section for an inelastic scattering process is obtained under the following radically simplifying assumptions. The projectile is represented in its initial and final state by plane waves. All distortions are neglected whether they originate in an inelastic process or an elastic deflections of the charged particle by the nucleus. The perturbation of the atomic orbits between which the projectile induces transitions is neglected. Nonrelativistic hydrogenic wave functions are used for the electronic states. In …