As the only stable baryon, the nucleon is of crucial importance in particle physics. Since the nucleon is a building block for all atomic nuclei, there is a need to analyse the its structure in order to fully understand the essential properties of all atomic nuclei. After more than forty years of research on the nucleon, both the experimental and theoretical situations have matured to a point where a synthesis of the results becomes indispensable. Here, A.W. Thomas and W. Weise present a unique report on the extensive empirical studies, theoretical foundations and the different models of the nucleon. The appendices provide an extensive summary of formulae needed in practical calculations. From the contents: electromagnetic structure of the nucleon, weak probes of nucleon structure, deep inelastic lepton scattering on the nucleon; elements of QCD, aspects of non-perturbative QCD, Chiral Symmetry and nucleon structure, models of the nucleon
A modern understanding of the nucleon's spin structure is presented. Polarisation dependent deep inelastic experiments have shown that the helicity contribution of quarks to the nucleon spin is much smaller than expected from the simple quark model. This observation and the role of the triangle anomaly lead to the conclusion that gluons - if strongly polarised, might solve the spin problem of the nucleon. Therefore a direct gluon polarisation measurement is the one of main goals of the COMPASS experiment spin physics programme. New results for the gluon polarisation are obtained. The results strongly support the hypothesis, that the gluons inside the nucleon are weakly or not polarised. Therefore, the possible importance of quark and gluon angular momenta are discussed. A short review of the nucleon's spin structure results obtained in a Lattice Quantum Chromodynamics approach is presented. The concept that the presence of the angular momentum of quarks inside nucleon is related to the spatial deformation of the quark densities in the transverse plane is also reviewed.
The physics program with CLAS at Jefferson Lab has collected a large amount of data on the spin structure functions of the nucleon by using polarized electron beam directed on polarized NH3 and ND3 targets. In these experiments, the virtual photon asymmetry and the spin structure functions were measured with an unprecedented precision in a large kinematic range. The data help us to better understand the spin structure of the nucleon, especially in the transition region between hadronic and quark-gluon degrees of freedom. Therefore, it will be possible to put limits on quark-hadron duality, test pQCD predictions for the quark polarization at large Bjorken x, perform more precise calculations of higher-twist matrix elements in the framework of the Operator Product Expansion and get a glimpse of A1 at high x. In addition, using available proton and deuteron data together and utilizing a new unfolding technique, the spin structure functions for the neutron in the resonance region are extracted.
One of the missing keys in the present understanding of the spin structure of the nucleon is the contribution from the gluons: the so called gluon polarisation. This quantity can be determined in DIS through the Photon-Gluon Fusion (PGF) process, in which two analysis methods may be used: (i) identifying open charm events or (ii) selecting events with high transverse momentum (pT) hadrons. The data used in the present work were collected by the COMPASS Experiment, where a naturally polarised muon beam of 160 GeV, impinging on a polarised nucleon fixed target, is used. The results for the gluon polarisation from high pT are presented. The gluon polarisation result for high pT hadrons is divided, for the first time, into three independent x_G bins at leading order (LO). A new weighted method based on a neural network approach is used.
One of the main tasks of nuclear physics is the study of subatomic particles and their interactions. The nucleon-nucleon interactions have been extensively studied over the last decades and have been supported with plenty of experimental data. The discovery of a new quantum number, strangeness, and a new type of particles that contain it, hyperons, spurred a renewed interest in science. New classes of interactions, hyperon-nucleon, and hyperon- hyperon, evolved. One of the best ways to study such interactions is to place a hyperon inside a nucleus, where it serves as a probe of the internal structure and might manifest properties that cannot be seen in an ordinary nucleus. This book presents the high resolution spectroscopy of light to medium hypernuclei recently obtained in Jefferson Laboratory. The main emphasis is given to the physics of the core-excited states. The described analysis techniques allowed achieving high quality missing mass spectra with energy resolution of 400- 500 keV, an unprecedented value in the history of hypernuclear reaction spectroscopy.
Scientists use carefully designed experiments to acquire basic understanding of the physical world. A large number of physics experiments are done by scattering various particles to study their behavior thus to gain insight into how they interact. In studying the nuclear force, neutron-proton scattering provides an unique angle into learning how fundamental particles such as nucleons interact with each other. One basic parameter in describing the Nucleon-Nucleon (NN) interaction is the ?NN coupling constant, the precise value of which has been in great controversy. Different models of physics give values differing up to 10%. The accuracy of the ?NN coupling constant is important in understanding nucleon-nucleon interactions as well as other related phenomena such as chiral symmetry breaking in field theories and properties of two-nucleon systems such as the deuteron. In neutron-proton (np) scattering, the spin-transfer coefficient KNN' is a measurable quantity which directly relates to the ?+/- NN coupling constant, g2c. Precise measurement of the spin-transfer coefficient can be used to put constraint on the coupling constant, thus improve the accuracy of its value.
This work is the first step of a systematic study of incoherent electroproduction of pion mesons off the deuteron in the ?(1232) resonance region, it is taken by restriction to the impulse approximation, i.e., neglecting pion rescattering and two-body effects. The elementary operator for pion electroproduction from the nucleon is taken from the unitary isobar model (MAID) which is a model for single pion photo- and electroproduction off protons and neutrons. This approximation corresponds to the so-called spectator model in which the pion production takes place on a single nucleon inside the deuteron while the other nucleon acts merely as a spectator.
The book sheds light on the role of isospin degree of freedom in reaction dynamics of heavy-ion collisions via transverse in-plane flow. Role of the nuclear symmetry energy and nucleon-nucleon scattering cross section has been envisaged in detail. The investigations presented in the book revealed that the transverse flow can act as a very promising probe of the nuclear symmetry energy at supra-saturation density region, where the nuclear symmetry energy is highly uncertain. The details of nuclear dynamics involving neutron-rich colliding nuclei has also been presented. In short, this book encompasses gross features about the collision dynamics of transverse flow and its disappearance as well as related phenomena of isospin asymmetric nuclei.
Nucleon-Nucleon (NN) interaction derived from nuclear realistic potential, is used to study elastic and inelastic electron scattering form factors in light nuclei, where a microscopic theory is employed to include the effects of high configuration outside the 1p-shell model space, which is called core-polarization (cp) effects. Higher energy excitations from 1s-shell core orbits and also from the valence 1p-shell to higher allowed orbits up to 1d5/2 2s1/2 1d3/2 are considered for core-polarization calculations. the outlined theory of elastic and inelastic electron scattering were presented in chapter two. Chapter three of this book devoted to the derivation of the core-polarization effects with higher configuration in the first order perturbation theory and the two-body matrix elements of three part of the realistic interaction: central, spin orbit and strong tensor force, where the two-body matrix elements calculation in harmonic oscillator single-particle basis using Moshinisky transformation. Results,discussions and conclusion are presented in chapter four.
This book provides the relationship between the static stiffness and modal stiffness of structures. The applications of the use of these relationships will be also presented as reveled in physical structures. In the understanding of a structure, the stiffness of the structure is one measure of the ability of this structure, so that an understanding of the stiffness is very important. ‘Stiffness'' is the ability of a structure to receive the loads are compared with the deformation that occurs in these structures. The higher the value the greater rigidity of the structure the ability to receive loads. The static and dynamic loads are two type of loads which the first one is relatively simple than the second one. Exploring the relationship between the static stiffness and modal stiffness of a structure is the first main content of this book. The static stiffness and modal stiffness describes how stiff a structure is from different aspects. Establishing the relationship between the two stiffness will allow some results or methods used in structural dynamic to be used for solving static problems, and vice verse.
The starting concept is decomposed into system elements which have one function. For each system element a model is created that describes the behaviour of the element. Each system element model is than developed into a physical part of a MEMS system. During development the place on the structure and available space are closely monitored. Each part is designed for optimal resolution. The next step is to put all the physical MEMS parts together into a complete MEMS structure. With the MEMS structure defined, the last piece of the system can be designed. The controller is also the most essential part of the system because the MEMS structure itself is unstable during operation. The controller provides stability to the structure and is therefore very important. Bandwidth and stability are carefully balanced during the design of the controller.
Invariances – The Structure of the Objective World
The Secular Scripture – A Study if the Structure of Romance (Paper)
This thesis aims to explain the choice of capital structure in the times of crisis (2007-2009) for the U.S.A. real sector companies. The two main theories used are the trade-off theory and pecking order theory. The essential of the pecking order theory is that manager''s capital structure decisions are influenced by the market perceptions of managers'' superior information. The trade-off theory provides support for manager''s trade off between benefits and costs of debt. The conventional model is also used in the analysis in order to increase the robustness of the results. We find that the dynamic partial-adjustment model of the trade-off theory seems to explain better the choice of capital structure in the analyzed period than pecking order theory
This book focuses on the structure elucidation of pentacyclic triterpenes using to two essential techniques, Nuclear Magnetic Resonance and Mass Spectrometry. The Carbon-13 NMR data of most of the classes of pentacyclic triterpenes and their mass fragmentation pattern is provided and the characteristic 13C NMR signals and mass fragmentation peaks have also been described. Thus by comparing the data of an unknown pentacyclic triterpene with the data of the known pentacyclic triterpenes provided in this book may help to narrow down the search for the structure of the compound.