Nuclear data requirements for fusion reactor nucleonics
International Nuclear Information System (INIS)
Nuclear data requirements for fusion reactor nucleonics are reviewed and the present status of data are assessed. The discussion is divided into broad categories dealing with data for Fusion Materials Irradiation Test Facility (FMIT), D-T Fusion Reactors, Alternate Fuel Cycles and the Evaluated Data Files that are available or would be available in the near future
Fusion reactor nucleonics: status and needs
International Nuclear Information System (INIS)
The national fusion technology effort has made a good start at addressing the basic nucleonics issues, but only a start. No fundamental nucleonics issues are seen as insurmountable barriers to the development of commercial fusion power. To date the fusion nucleonics effort has relied almost exclusively on other programs for nuclear data and codes. But as we progress through and beyond ETF type design studies the fusion program will need to support a broad based nucleonics effort including code development, sensitivity studies, integral experiments, data acquisition etc. It is clear that nucleonics issues are extremely important to fusion development and that we have only scratched the surface
International Nuclear Information System (INIS)
This Safety Evaluation Report for the application filed by the University of Oklahoma for a renewal of Operating License R-53 to continue to operate a research reactor has been prepared by the Office of Nuclear Reactor Regulation of the US Nuclear Regulatory Commission. The facility is owned and operated by the University of Oklahoma and is located on the campus in Norman, Cleveland County, Oklahoma. The staff concludes that the Aerojet General Nucleonics (AGN) reactor facility can continue to be operated by University of Oklahoma without endangering the health and safety of the public
Neutrino-driven nucleon fission reactors: Supernovae, quasars, and the big bang
International Nuclear Information System (INIS)
The purpose of this work is to establish the existence of naturally occurring celestial neutrino-driven nucleon fission chain reaction reactors as the first step in the development of controlled nucleon fission reactors on Earth. Celestial nucleon fission reactors provide functioning models that serve as starting points for reactor development. Recognizing supernovae, quasars, and the Big Bang as functioning neutrino-driven nucleon fission reactors presents the nuclear industry with a new and significant challenge. That challenge is our technological prowess to achieve a controlled nucleon fission chain reaction using the Earth's resources
Comparison of calculational methods for EBT reactor nucleonics
International Nuclear Information System (INIS)
Nucleonic calculations for a preliminary conceptual design of the first wall/blanket/shield/coil assembly for an EBT reactor are described. Two-dimensional Monte Carlo, and one- and two-dimensional discrete-ordinates calculations are compared. Good agreement for the calculated values of tritium breeding and nuclear heating is seen. We find that the three methods are all useful and complementary as a design of this type evolves
Assessment of nucleonic methods and data for fusion reactors
International Nuclear Information System (INIS)
An assessment is provided of nucleonic methods, codes, and data necessary for a sound experimental fusion power reactor (EPR) technology base. Gaps in the base are identified and specific development recommendations are made in three areas: computational tools, nuclear data, and integral experiments. The current status of the first two areas is found to be sufficiently inadequate that viable engineering design of an EPR is precluded at this time. However, a program to provide the necessary data and computational capability is judged to be a low-risk effort
International Nuclear Information System (INIS)
The general properties of the nucleon-nucleon potentials are reviewed. The comparison between experimental nucleon-nucleon phase shifts and deuteron properties and the theoretical ones derived with Hamada-Johnston, Reid, Paris and Bonn potentials is discussed. Also, Hartree-Fock calculations for several spherical nuclei using Skyrme's density-dependent effective nucleon-nucleon interaction are presented systematically.(author)
International Nuclear Information System (INIS)
Nucleon-nucleon interactions are at the heart of nuclear physics, bridging the gap between QCD and the effective interactions appropriate for the shell model. We discuss the current status of NN data sets, partial-wave analyses, and some of the issues that go into the construction of potential models. Our remarks are illustrated by reference to the Argonne v18 potential, one of a number of new potentials that fit elastic nucleon-nucleon data up to 350 MeV with a Χ2 per datum near 1. We also discuss the related issues of three-nucleon potentials, two-nucleon charge and current operators, and relativistic effects. We give some examples of calculations that can be made using these realistic descriptions of NN interactions. We conclude with some remarks on how our empirical knowledge of NN interactions may help constrain models at the quark level, and hence models of nucleon structure
Subcriticality Evaluation of AGN-201 Reactor Using Modified Neutron Source Multiplication Method
International Nuclear Information System (INIS)
One of the main issues in nuclear criticality safety is to measure subcriticality accurately at nuclear facility containing fissile materials. In order to verify the feasibility and safety of reactor, reactor physics test is performed in the commercial reactor. Among these test items, the measurement of control rod worth is taken most of period of reactor physics test. For that reason, the new methods have been introduced for subcriticality measurement to reduce the test period from the economic point of view : for example, pulse neutron method, neutron noise analysis method, Neutron Source Multiplication (NSM) method and so on. In 1980's, the research for subcriticality measurement methodology was performed about accelerator driven system, fast breeder reactor and critical experiment reactor. In this study, subcritcality is evaluated by modified NSM method. It is based on the conventional NSM method adding two correction processes: extraction of the fundamental mode from measuring neutron count rate data that contains not only fundamental mode but also higher modes in real situation and spatial corrections for perturbation induced by a reactivity addition in the distributions of the fundamental mode and a neutron importance field. In the previous studies, the verification of this method has been firstly performed for the subcriticality measurement of critical assembly of Kyoto University Critical Assembly (KUCA) at Kyoto University Research Reactor Institute in Japan. Recently subcriticality measurement study for the Pressurized Water Reactor (PWR) has been carried out. In the present study, the subcriticality was evaluated for Aerojet General Nucleonics (AGN)-201 reactor by the modified NSM method with two correction processes. The AGN-201 reactor is the graphite moderated homogeneous type research reactor and is used for reactor experiments such as critical mass approach, control rod calibration, measurement of neutron flux and so on. For subcriticality
International Nuclear Information System (INIS)
The physical importance of nucleon-nucleon diffraction and the main differences with well understood nucleon nucleus diffraction is discused. In the theoretical description of nucleon-nucleon diffraction in terms of the eikonal model, the hypothesis of factorization is shown to be in contradiction with the energy dependence of the impact parameter profile in proton-proton scattering at CERN - ISR. This dependence is highly non-uniform in impact parameter, giving rise to a pronounced peripheral increase with energy of the inelastic overlap function. Two experimental findings in inelastic diffraction indicate the existence of a deep relation of this process with the peripheral increase of the profile function. The first refers to the clear-cut proof that inelastic diffraction is peripheral in impact parameter space, in coherent production on deuteron. The second is the analysis of the integrated cross sections for inelastic diffraction, which leads to the conclusion that most of the total cross section increase in the ISR energy range comes from this process. It is then clear that the eikonal model should be modified in order to include inelastic diffraction. A recent trial in this direction by Miettinen and Thomas shows the existence of a substantial difference between the matter and the charge distribution inside the proton. Their results favours a description of the proton in terms of the string model. (Author)
International Nuclear Information System (INIS)
This book is an introduction to the interactions of nucleons with special regards to their contribution to nuclear forces. After a general description of the nuclear structure as a configuration of many nucleons the properties and interactions of nucleons are described with an excursion to the fundamental processes governing them. Then nuclear energy levels are considered. Thereafter nuclear energy-level transitions are described in the framework of the governing elementary processes. Finally nuclear reactions are considered in this framework. This book is suited as a supplement to a textbook in nuclear physics for students, who want to get a deeper insight in the fundamental processes in nuclei. (HSI)
Nucleon-nucleon interactions and observables
International Nuclear Information System (INIS)
A class of nucleon-nucleon interactions which are exactly phase equivalent to a given realistic nucleon-nucleon interaction is exhibited. These interactions have the property that the rms radius of the deuteron can be made arbitrarily large without changing the deuteron binding energy or any of the nucleon-nucleon scattering matrix elements. With this construction it is possible to find realistic interactions that do not obey the linear relation between the rms radius and the triplet scattering length observed by Klarsfeld et al.. The interpretation of this result is discussed. copyright 1998 The American Physical Society
Nucleon-nucleon theory and phenomenology
International Nuclear Information System (INIS)
This project involves five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 0-1200 MeV range that can be used by all nucleon-nucleon reseachers
Energy Technology Data Exchange (ETDEWEB)
Cornelis de Jager
2004-09-01
The experimental and theoretical status of elastic electron scattering from the nucleon is reviewed. As a consequence of new experimental facilities, data of unprecedented precision have recently become available for the electromagnetic and the strange form factors of the nucleon.
International Nuclear Information System (INIS)
In this paper, the role of three-nucleon forces in ab initio calculations of nuclear systems is investigated. The difference between genuine and induced many-nucleon forces is emphasized. Induced forces arise in the process of solving the nuclear many-body problem as technical intermediaries toward calculationally converged results. Genuine forces make up the Hamiltonian. They represent the chosen underlying dynamics. The hierarchy of contributions arising from genuine two-, three- and many-nucleon forces is discussed. Signals for the need of the inclusion of genuine three-nucleon forces are studied in nuclear systems, technically best under control, especially in three-nucleon and four-nucleon systems. Genuine three-nucleon forces are important for details in the description of some observables. Their contributions to observables are small on the scale set by two-nucleon forces. (author)
International Nuclear Information System (INIS)
Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)
International Nuclear Information System (INIS)
This is the second Status Report under a co-operation agreement between Los Alamos National Laboratory and EIR in the field of 'Nucleonics and Particle Transport in Fusion Reactors', covering the period 1 July 1984 to 30 June 1986. Reported is research and development progress in several areas, including deterministic transport methods (TRISM code), stochastic transport methods (MCNP code), and cross-section processing technology (NJOY and TRANSX-CTR codes). Also, capabilities for the analysis of the lithium breeding module (LBM) experiments at the LOTUS facility are discussed. Most effort during this reporting period was devoted to the development of a compatible production version of TRISM at both institutes (including a code users' workshop), to analysis of LBM experiments, to the development of an unresolved resonance treatment in MCNP, to the development of new modules for NJOY, and to the generation of new neutron and photon cross-section libraries. (author)
Pionic background for nucleon-nucleon observables
International Nuclear Information System (INIS)
A method is presented that allows the unambiguous definition of the one pion exchange contribution to nucleon-nucleon scattering observables and then use it to determine those waves where values of phase shifts and mixing parameters may be understood as sums of pionic and non-pionic dynamical effects. This helps the assessment of the explicative power of the various existing phenomenological potentials and may eventually lead to ways of discriminating their effectiveness. (author) 16 refs.; 19 figs.; 2 tabs
Comparison of Relativistic Nucleon-Nucleon Interactions
Allen, T. W.; Payne, G. L.; Polyzou, Wayne N.
2000-01-01
We investigate the difference between those relativistic models based on interpreting a realistic nucleon-nucleon interaction as a perturbation of the square of a relativistic mass operator and those models that use the method of Kamada and Gl\\"ockle to construct an equivalent interaction to add to the relativistic mass operator. Although both models reproduce the phase shifts and binding energy of the corresponding non-relativistic model, they are not scattering equivalent. The example of el...
International Nuclear Information System (INIS)
Generalized parton distributions provide information on the longitudinal and transverse distribution of partons in the fast moving nucleon. Furthermore, they contain information on the spin structure of the nucleon. First results of a lattice study of generalized parton distributions are presented. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Kees de Jager
2002-10-01
A review of data on the nucleon electro-weak form factors in the space-like region is presented. Recent results from experiments using polarized beams and either polarized targets or nucleon recoil polarimeters have yielded a significant improvement on the precision of the electromagnetic data obtained with the traditional Rosenbluth separation. An outlook is presented of planned experiments.
Nucleon Electromagnetic Form Factors
International Nuclear Information System (INIS)
Although nucleons account for nearly all the visible mass in the universe, they have a complicated structure that is still incompletely understood. The first indication that nucleons have an internal structure, was the measurement of the proton magnetic moment by Frisch and Stern (1933) which revealed a large deviation from the value expected for a point-like Dirac particle. The investigation of the spatial structure of the nucleon, resulting in the first quantitative measurement of the proton charge radius, was initiated by the HEPL (Stanford) experiments in the 1950s, for which Hofstadter was awarded the 1961 Nobel prize. The first indication of a non-zero neutron charge distribution was obtained by scattering thermal neutrons off atomic electrons. The recent revival of its experimental study through the operational implementation of novel instrumentation has instigated a strong theoretical interest. Nucleon electro-magnetic form factors (EMFFs) are optimally studied through the exchange of a virtual photon, in elastic electron-nucleon scattering. The momentum transferred to the nucleon by the virtual photon can be selected to probe different scales of the nucleon, from integral properties such as the charge radius to scaling properties of its internal constituents. Polarization instrumentation, polarized beams and targets, and the measurement of the polarization of the recoiling nucleon have been essential in the accurate separation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor
Nucleon-nucleon scattering phase shifts
International Nuclear Information System (INIS)
Here are presented 0 to 800 MeV nucleon-nucleon elastic and inelastic phase parameters derived by several groups: Arndt and Roper; Hoshizaki; Bugg; Bystricky, Lechanoine, and Lehar; and Bryan, Clark, and VerWest. Resonant-like behavior appears in the 1D2 and 3F3 states above the inelastic threshold in Hoshizaki's analysis but not in Arndt and Roper's. The np data are inadequate to permit determination of the I = O phase parameters above 600 MeV. 27 references
International Nuclear Information System (INIS)
The problem of temperature dependence of nucleon mass is addressed by considering a retarded correlator of two currents with quantum numbers of a nucleon at finite temperature T π in the chiral limit. It is shown that at Euclidean momenta the leading one-loop corrections arise from direct interaction of thermal pions with the currents. A dispersive representation for the correlator shows that this interaction smears the nucleon pole over frequency interval with width ∼ T. This interaction does not change the exponential fall-off of the correlator in Euclidean space but gives an O(T2/Fπ2) contribution to the pre-exponential factor. 11 refs. (author)
Short-Range Nucleon-Nucleon Correlations
Arrington, J; Rosner, G; Sargsian, M
2011-01-01
The strong interaction of nucleons at short distances leads to a high-momentum component to the nuclear wave function, associated with short-range correlations between nucleons. These short-range, high-momentum structures in nuclei are one of the least well understood aspects of nuclear matter, relating to strength outside of the typical mean-field approaches to calculating the structure of nuclei. While it is difficult to study these short-range components, significant progress has been made over the last decade in determining how to cleanly isolate short-range correlations in nuclei. We have moved from asking if such structures exist, to mapping out their strength in nuclei and studying their microscopic structure. A combination of several different measurements, made possible by high-luminosity and high-energy accelerators, coupled with an improved understanding of the reaction mechanism issues involved in studying these structures, has led to significant progress, and provided significant new information ...
International Nuclear Information System (INIS)
The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Shahveh, Abolfazl [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of); Taghavi-Shahri, Fatemeh [School of Particles and Accelerators, Institute for Research in Fundamental, Sciences (IPM) P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Arash, Firooz, E-mail: farash@cic.aut.ac.i [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of)
2010-07-12
In the context of the so-called valon model, we calculate ({delta}g)/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of ({delta}g)/g in the measured kinematical region should not be interpreted as {delta}g being small. In fact, {delta}g itself at small x, and the first moment of the polarized gluon distribution in the nucleon, {Delta}g(Q{sup 2}), are large.
International Nuclear Information System (INIS)
In the context of the so-called valon model, we calculate (δg)/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of (δg)/g in the measured kinematical region should not be interpreted as δg being small. In fact, δg itself at small x, and the first moment of the polarized gluon distribution in the nucleon, Δg(Q2), are large.
Shahveh, Abolfazl; Taghavi-Shahri, Fatemeh; Arash, Firooz
2010-07-01
In the context of the so-called valon model, we calculate δg/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of δg/g in the measured kinematical region should not be interpreted as δg being small. In fact, δg itself at small x, and the first moment of the polarized gluon distribution in the nucleon, Δg (Q2), are large.
Medium corrections to nucleon-nucleon interactions
International Nuclear Information System (INIS)
The Bethe-Goldstone equations have been solved for both negative and positive energies to specify two nucleon G-matrices fully off of the energy shell. Medium correction effects of Pauli blocking and of the auxiliary potential are included in infinite matter systems characterized by fermi momenta in the range 0.5 fm-1 to 1.8 fm-1. The Paris interaction is used as the starting potential in most calculations. Medium corrections are shown to be very significant over a large range of energies and densities. On the energy shell values of G-matrices vary markedly from those of free two nucleon (NN) t-matrices which have been solved by way of the Lippmann-Schwinger equation. Off of the energy shell, however, the free and medium corrected Kowalski-Noyes f-ratios rate are quite similar suggesting that a useful model of medium corrected G-matrices are appropriately scaled free NN t-matrices. The choice of auxiliary potential form is also shown to play a decisive role in the negative energy regime, especially when the saturation of nuclear matter is considered. 30 refs., 7 tabs., 7 figs
Deconstructing triplet nucleon-nucleon scattering
International Nuclear Information System (INIS)
Nucleon-nucleon scattering in spin-triplet channels is analyzed within an effective field theory where one-pion exchange is treated nonperturbatively. Justifying this requires the identification of an additional low-energy scale in the strength of that potential. Short-range interactions are organized according to the resulting power counting, in which the leading term is promoted to significantly lower order than in the usual perturbative counting. In each channel there is a critical momentum above which the waves probe the singular core of the tensor potential and the new counting is necessary. When the effects of one- and two-pion exchange have been removed using a distorted-wave Born approximation, the residual scattering in waves with L≤2 is well described by the first three terms in the new counting. In contrast, the scattering in waves with L≥3 is consistent with the perturbative counting, at least for energies up to 300 MeV. This pattern is in agreement with estimates of the critical momenta in these channels
Cluster model of self-consistent nucleon states in nucleons
International Nuclear Information System (INIS)
Self-consistent cluster model of nucleon states in a nuclear medium is built up. Numerical solution of the Schroedinger nonlinear equation for nucleon self-consistent field is found. The calculated energy is close to the binding energy of nucleons in a nucleus
Axial structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
2002-01-01
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
Nucleon structure using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, C.; Kallidonis, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Constantinou, M.; Hatziyiannakou, K. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Drach, V. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Jansen, K. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Koutsou, G.; Vaquero, A. [The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Leontiou, T. [Frederick Univ, Nicosia (Cyprus). General Dept.
2013-03-15
A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distribution are discussed, assessing the methods applied for their study, including approaches to evaluate the disconnected contributions. Results on the spin carried by the quarks in the nucleon are also presented.
Nucleon-nucleon correlations in dense nuclear matter
International Nuclear Information System (INIS)
In this thesis new results on the problematics of the formation of nucleon-nucleon correlations in nuclear matter could be presented. Starting from a general study of the two-particle problem in matter we studied the occurrence of a suprafluid phase (pair condensate of nucleons). The Gorkov decoupling by means of anomalous Green functions was generalized, so that also Cooper pairs with spin 1 (triplet pairing) can be described. A generalized gap equation resulted, which permits to determine the order parameters of the suprafluied phase in arbitrary channels of the nucleon-nucleon scattering states. This equation was solvd in the 1S0-, in the 3P2-3F2, and in the 3S1-3D1 channel under application of realistic nucleon-nucleon potentials. The behaviour of the resulting gap parameters in the single channels was studied as function of density and temperature. (orig.)
Nucleon-nucleon scattering in a nonrelativistic quark model
International Nuclear Information System (INIS)
The aim of the present thesis is to understand the nucleon-nucleon interaction starting from a nonrelativistic quark model. In the framework of a quark model first a classification of 3q and 6q states is given which serve as basis for the calculations on the nucleon-nucleon scattering performed by means of the refined resonating-group method. For the comparison the results for the s-, p-, and d-phases are confronted to the results of conventional calculations in the meson-exchange picture (Bonn potential) on the ρ + ω exchange. Additionally to the one-gluon exchange potential phenomenological potentials are regarded in the calculations which make a comparison with experimentally determined nucleon-nucleon scattering phases possible. (orig.)
Nucleon-Nucleon Parity Violation Experiments
Van Oers, W T H
1999-01-01
Measurements of parity-violating longitudinal analyzing powers Az (normalized asymmetries) in polarized proton-proton scattering and in polarized neutron capture on the proton (n+p -> d+gamma) provide a unique window on the interplay between the weak and strong interactions between and within hadrons. Several new proton-proton parity violation experiments are presently either being performed or are being prepared for execution in the near future: at TRIUMF at 221 MeV and 450 MeV and at COSY (Forschungszentrum Jülich) in the multi-GeV range. A new measurement of the parity-violating gamma ray asymmetry with a ten-fold improvement in the accuracy over previous measurements is being developed at LANSCE. These experiments are intended to provide stringent constraints on the set of six effective weak meson-nucleon coupling constants, which characterize the weak interaction between hadrons in the energy domain where meson exchange models provide an appropriate description. The 221 MeV pp experiment is unique in th...
The nucleon-nucleon potential beyond the static approximation
Mondejar, Jorge; Soto, Joan
2006-01-01
We point out that, due to the use of static nucleon propagators in Heavy Baryon Chiral Perturbation Theory, the current calculations of the nucleon-nucleon potential miss certain contributions starting at two loops. These contributions give rise to contact interactions, which are both parametrically and numerically more important than the so called NNLO potentials. They show a peculiar dependence on the light quark masses, which should be taken into account when performing chiral extrapolatio...
The nucleon-nucleon potential beyond the static approximation
Mondejar, J; Mondejar, Jorge; Soto, Joan
2006-01-01
We point out that, due to the use of static nucleon propagators in Heavy Baryon Chiral Perturbation Theory, the current calculations of the nucleon-nucleon potential miss certain contributions starting at two loops. These contributions give rise to contact interactions, which are both parametrically and numerically more important than the so called NNLO potentials. They show a peculiar dependence on the light quark masses, which should be taken into account when performing chiral extrapolations of lattice data.
Quark bags, P-matrix and nucleon-nucleon scattering
International Nuclear Information System (INIS)
This paper is an extended version of the talk given at IX European Conference on Few Body Problems in Physics, Tbilisi, 1984. It reviews recent developments of the quark compound bag (QCB) model including explicit examples of the QCB nucleon-nucleon potentials, description of the deuteron properties, calculation of the six quark admixture in the deuteron and applications to the three-nucleon system
Technical data on nucleonic gauges
International Nuclear Information System (INIS)
This nucleonic gauge manual and directory provides a reference database of nucleonic control systems available to potential users in the fields of exploration, exploitation and processing of natural resources and in the manufacturing industries. It starts with background information an the general principals of nucleonic gauges, followed by portable nuclear analysis systems (PNAS), computer tomography, cost-benefit on NCS (Nucleonic Control Systems) applications and trends and transfer of NCS technology. It continues with radiation protection and safety, discusses nucleonic gauges with low radioactivity sources and ends with typical models of nucleonic gauges. The basic principles of the most popular techniques are reviewed and reference data links to suppliers are provided. Information sheets on many typical commercial devices are also included. It will help end-users to select the most suitable alternative to solve a particular problem or to measure a certain parameter in a specific process
Polarized lepton-nucleon scattering
International Nuclear Information System (INIS)
Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions
Polarized lepton-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Hughes, E.
1994-02-01
Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions.
International Nuclear Information System (INIS)
Nucleon-nucleon bremsstrahlung, NNγ, is a fundamental process, which involves the strong and electromagnetic fields acting simultaneously. Since the electromagnetic interaction is well known, NNγ provides a calculable tool for comparing off-energy-shell effects from different two-nucleon potentials compared to experiment and also provides a simple testing ground, which is sensitive to meson-exchange-current contributions that are so important in electronuclear physics. Historically, experimental studies have focused on ppγ, with only a few measurements of npγ. The present workshop was organized primarily to investigate the interest in, the value of, and the feasibility of doing an npγ experiment using the neutron white source at LANL. An increasing amount of US nuclear physics dollars are being spent on electronuclear physics. npγ is a fundamental process with large meson-exchange currents. In the npγ calculations of Brown and Franklin, the meson-exchange contributions increase the cross section by a factor of roughly two and later the angular distribution of the emitted photon dramatically. The details of these calculated effects have never been verified experimentally, but the proper quantum-mechanical inclusion of meson-exchange contributions, using the methods of brown and Franklin, has proved to be essential in understanding the heavy-ion results. The understanding of the importance of such terms is extremely important inelectronuclear processes, such as are presently under investigation or being planned at Bates, SLAC, and CEBAF. Just one example is in the electrodisintegration of the deuteron, where meson-exchange contributions must be included properly before any conclusions about nuclear models, such as QCD versus meson-exchange potentials can be made
Few-nucleon systems with state-of-the-art chiral nucleon-nucleon forces
Binder, S.; Calci, A.; Epelbaum, E.; Furnstahl, R. J.; Golak, J.; Hebeler, K.; Kamada, H.; Krebs, H.; Langhammer, J.; Liebig, S.; Maris, P.; Meißner, Ulf-G.; Minossi, D.; Nogga, A.; Potter, H.; Roth, R.; Skibiński, R.; Topolnicki, K.; Vary, J. P.; Witała, H.; Lenpic Collaboration
2016-04-01
We apply improved nucleon-nucleon potentials up to fifth order in chiral effective field theory, along with a new analysis of the theoretical truncation errors to study nucleon-deuteron (N d ) scattering and selected low-energy observables in 3H,4He , and 6Li. Calculations beyond second order differ from experiment well outside the range of quantified uncertainties, providing truly unambiguous evidence for missing three-nucleon forces within the employed framework. The sizes of the required three-nucleon-force contributions agree well with expectations based on Weinberg's power counting. We identify the energy range in elastic N d scattering best suited to study three-nucleon-force effects and estimate the achievable accuracy of theoretical predictions for various observables.
Nucleon Strangeness and Unitarity
Musolf, M. J.; Hammer, H. -W.; D. Drechsel(Institut f. Kernphysik, Mainz)
1996-01-01
The strange-quark vector current form factors of the nucleon are analyzed within the framework of dispersion relations. Particular attention is paid to contributions made by $K\\bar{K}$ intermediate states to the form factor spectral functions. It is shown that, when the $K\\bar{K}\\to N\\bar{N}$ amplitude is evaluated in the Born approximation, the $K\\bar{K}$ contributions are identical to those arising from a one-loop calculation and entail a serious violation of unitarity. The mean square stra...
Renormalization of EFT for nucleon-nucleon scattering
Yang, J. -F.
2004-01-01
The renormalization of EFT for nucleon-nucleon scattering in nonperturbative regimes is investigated in a compact parametrization of the $T$-matrix. The key difference between perturbative and nonperturbative renormalization is clarified. The underlying theory perspective and the 'fixing' of the prescriptions for the $T$-matrix from physical boundary conditions are stressed.
Evidence for dibaryon resonances in nucleon-nucleon scattering
International Nuclear Information System (INIS)
There has been a revival of interest in the subject of nucleon-nucleon resonances in the past 3 to 4 years, largely generated by experimental results from the polarized beam program at the Argonne ZGS. Evidence from experimental results and phase shift and phenomenological analyses incorporating these results regarding the existence of these resonances is summarized. 20 figures
Meson exchange model for the nucleon-nucleon interaction
International Nuclear Information System (INIS)
Nucleon-nucleon interactions obtained from several models for the field theoretic scattering amplitude are studied. The interaction includes contributions from one-pion and one-omega exchange and from two-pion exchange as calculated in a dispersion theory framework. The resulting interaction is regularized by a cut-off factor obtained by the eikonal approximation to multiple vector meson exchange processes. The Blankenbecler-Sugar equation is solved with the interaction and nucleon-nucleon scattering phase parameters are computed. For the best model good agreement with phenomenological phase parameters is achieved for physically reasonable values of the meson-nucleon coupling constants and the spectral functions needed for the evaluation of the two-pion exchange effects. The deuteron wave function is computed as are the deuteron charge and quadrupole form factors. The interaction is shown to have significantly weaker short-range repulsion than commonly found in local phenomenological potentials and in one-boson exchange models. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Deur, Alexandre
2009-12-01
We discuss the Jefferson Lab low momentum transfer data on moments of the nucleon spin structure functions $g_1$ and $g_2$ and on single charged pion electroproduction off polarized proton and polarized neutron. A wealth of data is now available, while more is being analyzed or expected to be taken in the upcoming years. Given the low momentum transfer selected by the experiments, these data can be compared to calculations from Chiral Perturbation theory, the effective theory of strong force that should describe it at low momentum transfer. The data on various moments and the respective calculations do not consistently agree. In particular, experimental data for higher moments disagree with the calculations.The absence of contribution from the $\\Delta$ resonance in the various observables was expected to facilitate the calculations and hence make the theory predictions either more robust or valid over a larger $Q^2$ range. Such expectation is verified only for the Bjorken sum, but not for other observables in which the $\\Delta$ is suppressed. Preliminary results on pion electroproduction off polarized nucleons are also presented and compared to phenomenological models for which contributions from different resonances are varied. Chiral Perturbation calculations of these observables, while not yet available, would be valuable and, together with these data, would provide an extensive test of the effective theory.
Nucleon-antinucleon interaction
International Nuclear Information System (INIS)
The current status of our understanding of the low energy nucleon-antinucleon (N anti N) interaction is reviewed. We compare several phenomenological models which fit the available N anti N cross section data. The more realistic of these models employ an annihilation potential W(r) which is spin, isospin and energy dependent. The microscopic origins for these dependences are discussed in terms of quark rearrangement and annihilation processes. It is argued that the study of N anti N annihilation offers a powerful means of studying quark dynamics at short distances. We also discuss how one may try to isolate coherent meson exchange contributions to the medium and long range part of the N anti N potential. These pieces of the N anti N interaction are calculable via the G-parity transformation from a model for the NN potential; their effects are predicted to be seen in N anti N spin observables, to be measured at LEAR. The possible existence of quasi-stable bound states or resonances of the anti N plus one or more nucleons is discussed, with emphasis on few-body systems. 42 references
International Nuclear Information System (INIS)
The Soudan nucleon decay program is being carried out in the Soudan iron mine in northeastern Minnesota, at a depth of 2000 m of water equivalent. A 30-ton prototype experiment, Soudan 1, has been built and is now being operated by a University of Minnesota - Argonne National Laboratory collaboration. The detector is a block of iron-loaded concrete instrumented with 3456 gas proportional tubes. It can detect nucleon decay at the 2 x 1030 year level, and will measure cosmic-ray induced backgrounds. Soudan 1 is also obtaining data on very high energy cosmic-ray interactions. Monte-Carlo predictions of performance have been checked by calibration of a detector module in a charged-particle test beam. A proposal to build a 1000-ton experiment, Soudan 2, has been submitted to funding agencies in the USA and the UK by a Minnesota - Argonne - Oxford University collaboration. The proposed detector utilizes drift chambers with 50-cm drifts to obtain very fine-grained ionization and tracking information at low cost. This tracking-calorimeter detector has a fiducial mass of 650 tons, and could be operating in 1985. A drifting scheme utilizing 50 cm x 5 m x 1 cm planar chambers has been shown feasible, and prototypes of alternate drifting structures are also being studied. A plan to provide expandability to an eventual 5000 tons has been developed
Burkert, Volker D
2016-01-01
Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and $\\Delta$ states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger Equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of $Q^2 > 1.5GeV^2$. In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degre...
Flavor Decomposition of the Nucleon
Melnitchouk, W.
1999-01-01
I review some recent developments in the study of quark flavor distributions in the nucleon, including (i) valence quark distributions and the quark-hadron duality prediction for the x -> 1 d/u ratio (ii) sea quark asymmetries and electromagnetic form factors (iii) strange quarks in the nucleon.
Pion distribution in the nucleon
International Nuclear Information System (INIS)
A model is presented for calculating the pion wave function inside the nucleon. By assuming that all pions around a core of the nucleon are in the lowest eigenstate of the system, it is shown that both the bound state and πN scattering amplitude can be consistently described by an exactly soluble model defined in the subspace spanned by the core state and the physical πN state. The parameters of the model are determined by fitting the data of the nucleon mass, πNN coupling constant and low energy πN scattering phase shifts. The model predicts that the probability of finding the pion component inside the nucleon is about 20%. The calculated πNN form factor differs significantly from the conventional monopole form. The dynamical consequences of the differences are demonstrated in a calculation of electromagnetic production of pions from the nucleon and the deuteron. 7 refs., 4 figs., 1 tab
Three pion nucleon coupling constants
Arriola, E Ruiz; Perez, R Navarro
2016-01-01
There exist four pion nucleon coupling constants, $f_{\\pi^0, pp}$, $-f_{\\pi^0, nn}$, $f_{\\pi^+, pn} /\\sqrt{2}$ and $ f_{\\pi^-, np} /\\sqrt{2}$ which coincide when up and down quark masses are identical and the electron charge is zero. While there is no reason why the pion-nucleon-nucleon coupling constants should be identical in the real world, one expects that the small differences might be pinned down from a sufficiently large number of independent and mutually consistent data. Our discussion provides a rationale for our recent determination $$f_p^2 = 0.0759(4) \\, , \\quad f_{0}^2 = 0.079(1) \\,, \\quad f_{c}^2 = 0.0763(6) \\, , $$ based on a partial wave analysis of the $3\\sigma$ self-consistent nucleon-nucleon Granada-2013 database comprising 6713 published data in the period 1950-2013.
International Nuclear Information System (INIS)
A nucleonic measuring instrument is described wherein a housing contains a radiation source and has an aperture controlled by a shutter which is spring loaded to a closed position for confining and shielding the radiation and is movable by a motor to an open position for releasing the radiation, the motor being supplied with power through a heat sensitive element so that it is deenergized and the shutter closes in response to a predetermined high ambient temperature such as may be caused by a fire, and including an explosive blank cartridge positioned in relation to the shutter guide which explodes in response to a still higher ambient temperature, deforming the guide and thereby locking the shutter in the closed position. (auth)
Nucleon Spin Structure: Experiment
Miller, Andy
2003-04-01
The experimental study of nucleon spin structure is at a transitional stage. Deeply inelastic scattering of leptons has revealed much about quark helicity distributions, and is approaching the limits of what is possible with present experimental facilities. The latest results from semi-inclusive measurements at HERMES will be presented. Precise new complementary data are expected soon from W production at RHIC-Spin. The gluon polarization will also be measured soon at COMPASS and RHIC. Meanwhile, single-spin asymmetries that promise to provide access to the unknown transversity distribution have been observed, and will be discussed. Based on these signals, the first measurements of transversity are underway. Finally, single spin asymmetries have also been recently observed in hard exclusive processes such as deeply virtual Compton scattering. These signals have the potential to provide a new window on both orbital angular momentum of partons, and on correlations between their longitudinal momentum and transverse position.
Nucleon Electromagnetic Form Factors
Energy Technology Data Exchange (ETDEWEB)
Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi
2007-10-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.
International Nuclear Information System (INIS)
Purpose: To provide a spray cooling structure wherein the steam phase in a bwr reactor vessel can sufficiently be cooled and the upper cap and flanges in the vessel can be cooled rapidly which kept from direct contaction with cold water. Constitution: An apertured shielding is provided in parallel spaced apart from the inner wall surface at the upper portion of a reactor vessel equipped with a spray nozzle, and the lower end of the shielding and the inner wall of the vessel are closed to each other so as to store the cooling water. Upon spray cooling, cooling water jetting out from the nozzle cools the vapor phase in the vessel and then hits against the shielding. Then the cooling water mostly falls as it is, while partially enters through the apertures to the back of the shielding plate, abuts against stoppers and falls down. The stoppers are formed in an inverted L shape so that the spray water may not in direct contaction with the inner wall of the vessel. (Horiuchi, T.)
Induced Hyperon-Nucleon-Nucleon Interactions and the Hyperon Puzzle
Wirth, Roland
2016-01-01
We present the first ab initio calculations for $p$-shell hypernuclei including hyperon-nucleon-nucleon (YNN) contributions induced by a Similarity Renormalization Group transformation of the initial hyperon-nucleon interaction. The transformation including the YNN terms conserves the spectrum of the Hamiltonian while drastically improving model-space convergence of the Importance-Truncated No-Core Shell Model, allowing a precise extraction of binding and excitation energies. Results using a hyperon-nucleon interaction at leading order in chiral effective field theory for lower- to mid-$p$-shell hypernuclei show a good reproduction of experimental excitation energies while hyperon binding energies are typically overestimated. The induced YNN contributions are strongly repulsive and we show that they are related to a decoupling of the $\\Sigma$ hyperons from the hypernuclear system, i.e., a suppression of the $\\Lambda$-$\\Sigma$ conversion terms in the Hamiltonian. This is linked to the so-called hyperon puzzle ...
Regularization Methods for Nucleon-Nucleon Effective Field Theory
Steele, James V.; Furnstahl, R. J.
1998-01-01
Attempts to apply effective field theory (EFT) methods to nonrelativistic nucleon-nucleon (NN) scattering have raised questions about the nature and limitations of an EFT expansion when used nonperturbatively. We discuss the characteristics of a meaningful EFT analysis and compare them with traditional approaches to NN scattering. A key feature of an EFT treatment is a systematic expansion in powers of momentum, which we demonstrate using an error analysis introduced by Lepage. A clear graphi...
Probing effective nucleon-nucleon interaction at band termination
Satula, Wojciech
2006-01-01
Low-energy nuclear structure is not sensitive enough to resolve fine details of nucleon-nucleon (NN) interaction. Insensitivity of infrared physics to the details of short-range strong interaction allows for consistent, free of ultraviolet divergences, formulation of local theory at the level of local energy density functional (LEDF) including, on the same footing, both particle-hole as well as particle-particle channels. Major difficulty is related to parameterization of the nuclear LEDF and...
Electroexcitation of nucleon resonances
Energy Technology Data Exchange (ETDEWEB)
Inna Aznauryan, Volker D. Burkert
2012-01-01
We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited states, which have been measured in a range of Q2 up to 8 and 4.5 GeV2 for the Delta(1232)P33, N(1535)S11 and N(1440)P11, N(1520)D13, respectively. These results have been confronted with calculations based on lattice QCD, large-Nc relations, perturbative QCD (pQCD), and QCD-inspired models. The amplitudes for the Delta(1232) indicate large pion-cloud contributions at low Q2 and don't show any sign of approaching the pQCD regime for Q2<7 GeV2. Measured for the first time, the electroexcitation amplitudes of the Roper resonance, N(1440)P11, provide strong evidence for this state as a predominantly radial excitation of a three-quark (3q) ground state, with additional non-3-quark contributions needed to describe the low Q2 behavior of the amplitudes. The longitudinal transition amplitude for the N(1535)S11 was determined and has become a challenge for quark models. Explanations may require large meson-cloud contributions or alternative representations of this state. The N(1520)D13 clearly shows the rapid changeover from helicity-3/2 dominance at the real photon point to helicity-1/2 dominance at Q2 > 0.5 GeV2, confirming a long-standing prediction of the constituent quark model. The interpretation of the moments of resonance transition form factors in terms of transition transverse charge distributions in infinite momentum frame is presented.
Nucleon-Nucleon Scattering in a Three Dimensional Approach
Fachruddin, I; Glöckle, W; Elster, Ch.
2000-01-01
The nucleon-nucleon (NN) t-matrix is calculated directly as function of two vector momenta for different realistic NN potentials. To facilitate this a formalism is developed for solving the two-nucleon Lippmann-Schwinger equation in momentum space without employing a partial wave decomposition. The total spin is treated in a helicity representation. Two different realistic NN interactions, one defined in momentum space and one in coordinate space, are presented in a form suited for this formulation. The angular and momentum dependence of the full amplitude is studied and displayed. A partial wave decomposition of the full amplitude it carried out to compare the presented results with the well known phase shifts provided by those interactions.
Nucleon transfer between heavy nuclei
International Nuclear Information System (INIS)
Nucleon transfer reactions between heavy nuclei are characterized by the classical behaviour of the scattering orbits. Thus semiclassical concepts are well suited for the description of these reactions. In the present contribution the characteristics of single and multinucleon transfer reactions at energies below and above the Coulomb barrier are shown for systems like Sn+Sn, Xe+U and Ni+Pb. The role of the pairing interaction in the transfer of nucleon pairs is illustrated. For strong transitions the coupling of channels and the absorption into more complicated channels is taken into account in a coupled channels calculation
Stopped nucleons in configuration space
Bialas, Andrzej; Koch, Volker
2016-01-01
In this note, using the colour string model, we study the configuration space distribution of stopped nucleons in heavy-ion collisions. We find that the stopped nucleons from the target and the projectile end up separated from each other by the distance increasing with the collision energy. In consequence, for the center of mass energies larger than 6 or 10 GeV (depending on the details of the model) it appears that the system created is not in thermal and chemical equilibrium, and the net baryon density reached is likely not much higher than that already present in the colliding nuclei.
Hammer events, neutrino energies, and nucleon-nucleon correlations
Weinstein, L B; Piasetzky, E
2016-01-01
Neutrino oscillation measurements depend on a difference between the rate of neutrino-nucleus interactions at different neutrino energies or different distances from the source. Knowledge of the neutrino energy spectrum and neutrino-detector interactions are crucial for these experiments. Short range nucleon-nucleon correlations in nuclei (SRC) affect properties of nuclei. The ArgoNeut liquid Argon Time Projection Chamber (lArTPC) observed neutrino-argon scattering events with two protons back-to-back in the final state ("hammer" events) which they associated with SRC pairs. The MicroBoone lArTPC will measure far more of these events. We simulate hammer events using two simple models. We use the well-known electron-nucleon cross section to calculate e-argon interactions where the e- scatters from a proton, ejecting a pi+, and the pi+ is then absorbed on a moving deuteron-like $np$ pair. We also use a model where the electron excites a nucleon to a Delta, which then deexcites by interacting with a second nucle...
The Nucleon as a Holographic Cheshire Cat
Zahed, Ismail
2014-01-01
The Cheshire cat principle emerges naturally from the holographic approach of the nucleon in terms of a bulk instanton. The cat hides in the holographic direction. I briefly review the one-nucleon problem in the holographic limit.
The nucleon as a holographic Cheshire cat
International Nuclear Information System (INIS)
The Cheshire cat principle emerges naturally from the holographic approach of the nucleon in terms of a bulk instanton. The cat hides in the holographic direction. I briefly review the one-nucleon problem in the holographic limit
Gluon Spin Contribution to The Nucleon Spin
Energy Technology Data Exchange (ETDEWEB)
Arash, Firooz, E-mail: farash@cic.aut.ac.i [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of); Shahveh, Abolfazl [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of); Taghavi-Shahri, Fateme [School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM) P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
2010-10-15
We have calculated {delta}g/g in the nucleon at all measured kinematics. The smallness of {delta}g/g in the measured kinematics should not be interpreted as the the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, {Delta}g(Q{sup 2}) can be sizable.
Gluon Spin Contribution to The Nucleon Spin
Arash, Firooz; Shahveh, Abolfazl; Taghavi-Shahri, Fateme
2010-10-01
We have calculated δg/ g in the nucleon at all measured kinematics. The smallness of δg/ g in the measured kinematics should not be interpreted as the the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δ g( Q2) can be sizable.
Gluon Spin Contribution to The Nucleon Spin
International Nuclear Information System (INIS)
We have calculated δg/g in the nucleon at all measured kinematics. The smallness of δg/g in the measured kinematics should not be interpreted as the the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δg(Q2) can be sizable.
The quark structure of the nucleons
International Nuclear Information System (INIS)
The suitableness of the non-relativistic potential model for the description of quarks in nucleons is proved and the model extensively presented. Practical applications are some contributions to the nucleon-nucleon interaction which result from the quark structure of the nucleons. These are especially the quark-gluon exchange and the quark-pion exchange between nucleons. The influences of these interactions on the s and p scattering of the nucleons are calculated in the framework of the resonating-group method. Furthermore we study the change of the quark structure if two nucleons approach very closely. The interaction of the nucleons by quark-gluon exchange causes an increase of the nucleon radius and a shift of the quark momenta to lower values. On this base the momentum distribution of quarks in nuclei is calculated and a natural explanation of the EMC effect is given. The distance distribution of nucleons and their Fermi motion are calculated for this in the shell model. Then we make further considerations in connection with the flavor symmetry, the collapse of the nucleons and the properties of six-quark bags. Altogether it is shown that in the potential model the most different effects of the quark structure of nucleons can be surprisingly well described in an illustrative way. (orig.)
Nucleon mean free path in nuclear matter
International Nuclear Information System (INIS)
In calculations of nuclear reaction yields at incident energies of some tens of MeV consistently better agreement with experiments is obtained by assuming a nucleon mean free path in nuclear matter longer than that deduced from the Fermi gas model and free nucleon-nucleon cross sections. (Auth.)
Leading chiral logarithms for the nucleon mass
Energy Technology Data Exchange (ETDEWEB)
Vladimirov, Alexey A.; Bijnens, Johan [Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE 223 62 Lund (Sweden)
2016-01-22
We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the LLog series for the nucleon mass within the heavy baryon theory. The presented results are the first example of LLog calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass.
Chiral perturbation theory with nucleons
International Nuclear Information System (INIS)
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, πN scattering and the σ-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon
K^* Mesons and Nucleon Strangeness
Barz, L. L.; Forkel, H.; Hammer, H. -W.; Navarra, F. S.; Nielsen, M; Ramsey-Musolf, M. J.
1998-01-01
We study contributions to the nucleon strange quark vector current form factors from intermediate states containing K^* mesons. We show how these contributions may be comparable in magnitude to those made by K mesons, using methods complementary to those employed in quark model studies. We also analyze the degree of theoretical uncertainty associated with K^* contributions.
Nucleon structure from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Dinter, Simon
2012-11-13
In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a{sup 2}) discretization effects.
Nucleon structure from lattice QCD
International Nuclear Information System (INIS)
In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a2) discretization effects.
Holographic nucleons in the nuclear medium
Energy Technology Data Exchange (ETDEWEB)
Lee, Bum-Hoon, E-mail: bhl@sogang.ac.kr [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Center for Quantum Spacetime (CQUeST), Sogang University, Seoul 121-742 (Korea, Republic of); Park, Chanyong, E-mail: cyong21@sogang.ac.kr [Center for Quantum Spacetime (CQUeST), Sogang University, Seoul 121-742 (Korea, Republic of)
2015-06-30
We investigate the nucleon's rest mass and dispersion relation in the nuclear medium which is holographically described by the thermal charged AdS geometry. With this background, the chiral condensate plays an important role to determine the nucleon's mass in both the vacuum and the nuclear medium. It also significantly modifies the nucleon's dispersion relation. The nucleon's mass in the high density regime increases with density as expected, while in the low density regime it slightly decreases. We further study the splitting of the nucleon's energies caused by the isospin interaction with the nuclear medium.
Holographic nucleons in the nuclear medium
International Nuclear Information System (INIS)
We investigate the nucleon's rest mass and dispersion relation in the nuclear medium which is holographically described by the thermal charged AdS geometry. With this background, the chiral condensate plays an important role to determine the nucleon's mass in both the vacuum and the nuclear medium. It also significantly modifies the nucleon's dispersion relation. The nucleon's mass in the high density regime increases with density as expected, while in the low density regime it slightly decreases. We further study the splitting of the nucleon's energies caused by the isospin interaction with the nuclear medium
Chiral Symmetry and the Nucleon-Nucleon Interaction
Directory of Open Access Journals (Sweden)
Ruprecht Machleidt
2016-04-01
Full Text Available We review how nuclear forces emerge from low-energy quantum chromodynamics (QCD via chiral effective field theory (EFT. During the past two decades, this approach has evolved into a powerful tool to derive nuclear two- and many-body forces in a systematic and model-independent way. We then focus on the nucleon-nucleon (N N interaction and show in detail how, governed by chiral symmetry, the long- and intermediate-range of the N N potential builds up order by order. We proceed up to sixth order in small momenta, where convergence is achieved. The final result allows for a full assessment of the validity of the chiral EFT approach to the N N interaction.
Probing the effective nucleon-nucleon interaction at band termination
International Nuclear Information System (INIS)
Low-energy nuclear structure is not sensitive enough to resolve the fine details of the nucleon-nucleon (NN) interaction. The insensitivity of the low-energy (infrared) physics to the details of the short-range strong interaction allows for a consistent, free of high-energy (ultraviolet) divergences, formulation of a local theory at the level of the local energy density functional (LEDF) including on the same footing, particle-hole and particle-particle channels. A major difficulty is related to the parameterization of the nuclear LEDF and its density dependence. It is argued that the structural simplicity of terminating or isomeric states offers an invaluable source of information that can be used for fine-tuning of the NN interaction in general and the nuclear LEDF parameters in particular. Practical applications of terminating states at the level of LEDF and nuclear shell-model are discussed. (author)
One-loop diagrams in nucleon-nucleon scattering
International Nuclear Information System (INIS)
Within the framework of the Blankenbeckler-Sugar equations the effects of one-loop corrections to the driving force are studied in the two-nucleon system. In particular, contributions from the direct and crossed box two-pion exchange diagrams are calculated. An analysis is made at the one-loop level for both pseudoscalar and pseudovector pion-nucleon coupling using geometric unitarization. In a model with one boson exchanges it is shown that the agreement between the Bethe-Salpeter and the quasipotential results does not improve in all partial waves when the one-loop contributions are included. Various qualitative fits to the experimental data are presented for such a model
In-medium nucleon-nucleon potentials in configuration space
International Nuclear Information System (INIS)
Based on the thermodynamic Green function approach two-nucleon correlations in nuclear matter at finite temperatures are revisited. To this end, we derive phase-equivalent effective r-space potentials that include the effect of Pauli blocking at a given temperature and density. These potentials enter into a Schroedinger equation that is the r-space representation of the Galitskii-Feynman equation for two nucleons. We explore the analytical structure of the equation in the complex k-plane by means of Jost functions. We find that despite the Mott effect the correlation with deuteron quantum numbers are manifested as antibound states, i.e. as zeros of the Jost function on the negative imaginary axis of the complex momentum space. The analysis presented here is also suited for Coulombic systems. (author)
Parity violation in the nucleon-nucleon interaction
International Nuclear Information System (INIS)
A short review is presented of experiments designed to detect parity nonconservation (PNC) in the interaction between nucleons. A recent measurement of PNC in proton-proton scattering is described, and some of the methods which were developed to reduce systematic errors to less than or equal to 2 x 10-8 are discussed. The results of this experiment and of other measurements on PNC are compared to theoretical predictions
The nucleon phase of binary fission
International Nuclear Information System (INIS)
Full text: The main step of the fission process is a sharing-out of nucleons, within a 'nucleon-phase', between the valence shells of the primordial cluster of the internally-dissociated fissioning system and the valence shells of the 'A =126 nucleon core' of the nascent heavy fragment. The formation of an 'A = 82 nucleon core' in the nascent light fragment explains the asymmetric fission mode of the light actinide nuclei. The nucleon partition in the nucleon phase can be understood in the framework of chemical thermodynamics. The formation of an 'A = 126 nucleon core' in the nascent light fragment of heavier fissioning systems explains the symmetric fission mode of 258Fm and that of heavier nuclei. But the new phenomenon of 'barrier-free' fission, discovered in 258Fm (s.f.), plays in this system and all symmetrically fissioning superheavy nuclei a very important role. (author)
Nucleon mass splitting in the isospin medium
Lee, Bum-Hoon; Park, Chanyong
2014-01-01
Using the AdS/CFT correspondence, we investigate a nucleon mass splitting and nucleon-pion coupling in the isospin medium. We find that there exists a nucleon mass splitting which is exactly given by the half of the meson mass splitting because nucleon has the half isospin charge of the charged mesons. In addition, we also investigate the nucleon-pion coupling, which requires the modification of the known Abelian-type unitary gauge fixing term because non-Abelian fluctuations should be taken into account in the isospin medium. In this paper, after constructing an appropriate unitary gauge fixing term, we find that in spite of the nucleon's and meson's mass splittings, there is no nucleon-pion coupling splitting in the isospin medium.
Peripheral Nucleon-Nucleon Phase Shifts and Chiral Symmetry
Kaiser, N; Weise, W
1997-01-01
Within the one-loop approximation of baryon chiral perturbation theory we calculate all one-pion and two-pion exchange contributions to the nucleon-nucleon interaction. In fact we construct the elastic NN-scattering amplitude up to and including third order in small momenta. The phase shifts with orbital angular momentum $L\\geq2 $ and the mixing angles with $J\\geq2$ are given parameterfree and thus allow for a detailed test of chiral symmetry in the two-nucleon system. We find that for the D-waves the $2\\pi$-exchange corrections are too large as compared with empirical phase shifts, signaling the increasing importance of shorter range effects in lower partial waves. For higher partial waves, especially for G-waves, the model independent $2\\pi$-exchange corrections bring the chiral prediction close to empirical NN phase shifts. We propose to use the chiral NN phase shifts with $L\\geq 3$ as input in a future phase shift analysis. Furthermore, we compute the irreducible two-pion exchange NN-potentials in coordin...
Cottingham formula and nucleon polarisabilities
International Nuclear Information System (INIS)
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections - provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon polarisabilities. We evaluate the sum rule for the difference between the electric polarisabilities of proton and neutron by means of the available parameterisations of the data and compare the result with experiment. (orig.)
Nucleon structure from stochastic estimators
Bali, Gunnar S; Gläßle, Benjamin; Göckeler, Meinulf; Najjar, Johannes; Rödl, Rudolf; Schäfer, Andreas; Sternbeck, André; Söldner, Wolfgang
2013-01-01
Using stochastic estimators for connected meson and baryon three-point functions has successfully been tried in the past years. Compared to the standard sequential source method we trade the freedom to compute the current-to-sink propagator independently of the hadron sink for additional stochastic noise in our observables. In the case of the nucleon we can use this freedom to compute many different sink-momentum/polarization combinations, which grants access to more virtualities. We will present preliminary results on the scalar, electro-magnetic and axial form factors of the nucleon in $N_f=2+1$ lattice QCD and contrast the performance of the stochastic method to the sequential source method. We find the stochastic method to be competitive in terms of errors at fixed cost.
Cottingham formula and nucleon polarisabilities
Energy Technology Data Exchange (ETDEWEB)
Gasser, J.; Leutwyler, H. [Universitaet Bern, Albert Einstein Center for Fundamental Physics, Institut fuer theoretische Physik, Bern (Switzerland); Hoferichter, M. [Universitaet Bern, Albert Einstein Center for Fundamental Physics, Institut fuer theoretische Physik, Bern (Switzerland); Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, ExtreMe Matter Institute EMMI, Darmstadt (Germany); University of Washington, Institute for Nuclear Theory, Seattle, WA (United States); Rusetsky, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Bonn (Germany)
2015-08-15
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections - provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon polarisabilities. We evaluate the sum rule for the difference between the electric polarisabilities of proton and neutron by means of the available parameterisations of the data and compare the result with experiment. (orig.)
International Nuclear Information System (INIS)
The spin and flavor structure of quarks and gluons in nucleons and nuclei is more complicated than expected in the original naive quark model. Recent results which show some of the key failures of the naive picture are summarized here with emphasis on recent results from the HERMES experiment. Some future options to study the quarks structure in exclusive processes in electroproduction, photoproduction and pp annihilation are presented. (orig.)
Chiral symmetry and nucleon structure
Energy Technology Data Exchange (ETDEWEB)
Holstein, B.R. (Massachusetts Univ., Amherst, MA (United States). Dept. of Physics and Astromony Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory)
1992-01-01
Recently it has been realized that significant tests of the validity of QCD are available in low energy experiments (E < 500 MeV) by exploiting the property of (broken) chiral symmetry. This technique has been highly developed in The Goldstone boson sector by the work of Gasser and Leutwyler. Application to the nucleon system is much more difficult and is now being carefully developed.
Medium Influence of the Nucleon-Nucleon Cross Section on the Fragmentation
Institute of Scientific and Technical Information of China (English)
刘建业; 邢永忠; 郭文军
2003-01-01
Based on an isospin-dependent quantum molecular dynamics model we studied the influence of a medium correction of an isospin-dependent nucleon-nucleon cross section on the fragmentation at the intermediate energy heavy-ion collisions. We found that the medium correction from an isospin-dependent nucleon-nucleon cross section increases the dependence of the fragmentation on the isospin effect of in-medium nucleon-nucleon cross section, at the same time, the momentum-dependent interaction also produces an important role for enhancing the influence of the medium correction on the isospin effect of two-body collisions in the fragmentation process.
Fujiwara, Y; Kohno, M; Suzuki, Y
2004-01-01
Quark-model nucleon-nucleon and hyperon-nucleon interactions by the Kyoto- Niigata group are applied to the hypertriton calculation in a new three-cluster Faddeev formalism using the two-cluster resonating-group method kernels. The most recent model, fss2, gives a reasonable result similar to the Nijmegen soft-core model NSC89, except for an appreciable contributions of higher partial waves.
Nucleon localization in light and heavy nuclei
Zhang, C L; Nazarewicz, W
2016-01-01
An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate $\\alpha$-cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the cluster structures in deformed light nuclei and study the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the deformed harmonic oscillator model. Realistic calculations are carried out using self-consistent nuclear density functional theory with quantified energy density functionals optimized for fission studies. We study particle densities and spatial nucleon localization distributions for deformed cluster configurations of $^{8}$Be and $^{20}$Ne, and also along...
Spin observables in nucleon-nucleus scattering
International Nuclear Information System (INIS)
The curse of inelastic nucleon scattering and charge exchange has always been the enormous complexity of the nucleon-nucleon (N-N) interaction. This complexity, however, can also be viewed as the ultimate promise of nucleons as probes of nuclear structure. Given an adequate theoretical basis, inelastic nucleon scattering is capable of providing information not obtainable with other probes. Recently a revolution of experimental technique has taken place that makes it desirable to re-examine the question of what physics is ultimately obtainable from inelastic nucleon scattering. It is now feasible to perform complete polarization transfer (PT) experiments for inelastic proton scattering with high efficiency and excellent energy resolution. Programs to measure PT obsevables are underway at several laboratories, and results are beginning to appear. Objectives of this presentation are to examine how such experiments are done, and what physics is presently obtained and may ultimately be learned from them
On the resonance structure in nucleon-nucleon scattering
Kloet, W. M.; Tjon, J. A.
1981-10-01
A possible explanation of resonance-like structure in 1D 2 and 3F 3 proton-proton phase parameters at medium energy is suggested by the analysis of an exactly soluble coupled channel model. Looping in the Argand plot is mainly due to the nucleon-delta branch cut. This effect is already present in the NΔ box diagram, but is modified by higher order multiple scattering. Poles occur close to the NΔ branch point and originate from left-hand singularities in the unphysical sheet.
Pion production in nucleon-nucleon collisions at low energies
Energy Technology Data Exchange (ETDEWEB)
Baru, Vadim [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Epelbaum, Evgeny [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Filin, Arseniy [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Haidenbauer, Johann; Hanhart, Christoph [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany); Kudryavtsev, Alexander [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Lensky, Vadim [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); European Centre for Theoretical Studies in Nuclear Physics and Related Areas, Villazzano (Trento) (Italy); Meissner, Ulf G. [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany)
2010-07-01
With the advent of chiral perturbation theory, the low-energy effective field theory of QCD, high accuracy calculations for hadronic reactions with a controlled error estimation have become possible. We survey the recent developments in the reaction NN{yields}NN{pi} in chiral EFT. We argue that the counting scheme that acknowledges the large momentum transfer between the initial and the final nucleons allows for a consistent description of s- and p-wave pion production. The status of the theory for pion production in the isospin conserving case allows us to challenge charge symmetry breaking effects recently observed experimentally in pn{yields}d{pi}{sup 0}.
Nucleon Resonances in Meson Nucleon Scattering with Strangeness Production
Waluyo, A.; Bennhold, C.; Haberzettl, H.; Penner, G.; Mosel, U.; Mart, T.
2000-01-01
An effective Lagrangian model in a coupled channels framework is applied to extract nucleon resonance parameters. In the K-matrix approximation, we simultaneously analyze all the available data for the transitions from pi N to five possible meson-baryon final states, pi N, pipi N, eta N, K Lambda, and KSigma, in the energy range from pi N threshold up to W = 2 GeV. In this work, we focus our efforts on the K Sigma channel. In particular, we include a set of Delta resonances around 1900 MeV: t...
Chiral nucleon-nucleon forces in nuclear structure calculations
Directory of Open Access Journals (Sweden)
Coraggio L.
2016-01-01
Full Text Available Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
Bethe-Salpeter equation for elastic nucleon-nucleon scattering
International Nuclear Information System (INIS)
The Bethe-Salpeter equation for NN scattering with one-boson exchange is investigated for the case in which the pion-nucleon coupling is described by axial-vector theory. In contrast to the results with pseudoscalar coupling, good agreement with the experimental data can be obtained for all partial waves. Also, the deviations from the Blankenbecler-Sugar equation are not as large as they are for pseudoscalar coupling. In addition, cancellations between the direct and the crossed box graph with pseudoscalar πN coupling are investigated for the 3S1 phase shift in the framework of the variational operator Pade approximation
Chiral nucleon-nucleon forces in nuclear structure calculations
Coraggio, L; Holt, J W; Itaco, N; Machleidt, R; Marcucci, L E; Sammarruca, F
2016-01-01
Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
Database of Nucleon-Nucleon Scattering Cross Sections by Stochastic Simulation Project
National Aeronautics and Space Administration — A database of nucleon-nucleon elastic differential and total cross sections will be generated by stochastic simulation of the quantum Liouville equation in the...
Dissecting nucleon transition electromagnetic form factors
Segovia, Jorge
2016-01-01
In Poincar\\'e-covariant continuum treatments of the three valence-quark bound-state problem, the force behind dynamical chiral symmetry breaking also generates nonpointlike, interacting diquark correlations in the nucleon and its resonances. We detail the impact of these correlations on the electromagnetically-induced nucleon-$\\Delta$ and nucleon-Roper transitions, providing a flavour-separation of the latter and associated predictions that can be tested at modern facilities.
Orbital angular momentum in the nucleons
Lorcé, Cédric
2014-01-01
In the last decade, it has been realized that the orbital angular momentum of partons inside the nucleon plays a major role. It contributes significantly to nucleon properties and is at the origin of many asymmetries observed in spin physics. It is therefore of paramount importance to determine this quantity if we want to understand the nucleon internal structure and experimental observables. This triggered numerous discussions and controversies about the proper definition of orbital angular ...
Gluon Contribution To The Nucleon Spin
Arash, Firooz; Taghavi-Shahri, Fatemeh; Shahveh, Abolfazl
2011-07-01
Gluon polarization in Nucleon is evaluated in the valon representation of hadrons. It is shown that although δg/g is small at the currently measured kinematics, it does not imply that the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δg(Q2), is sizable. We also notice that the majority of Δg is concentrated at around x = 0.08.
Gluon Contribution To The Nucleon Spin
International Nuclear Information System (INIS)
Gluon polarization in Nucleon is evaluated in the valon representation of hadrons. It is shown that although δg/g is small at the currently measured kinematics, it does not imply that the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δg(Q2), is sizable. We also notice that the majority of Δg is concentrated at around x = 0.08.
Current status of nucleonic gauges in Portugal
International Nuclear Information System (INIS)
The nucleonic gauges are largely used in Portugal industry, despite the fact that design and manufacturing of prototypes of nucleonic gauges is rather limited. The modernization of some industrial sectors (cement, paper and civil engineering) has enhanced applications of nucleonic gauges and has created local capability but new legislation tends to restrict further spread of them. The Institute of Nuclear Technology is the only applied research institution developing nucleonic gauges for moisture, thickness and density, and elemental analysis, as well as providing assistance in calibration, safe operation and maintenance of them. (author)
Transversity of quarks in a nucleon
Indian Academy of Sciences (India)
K Bora; D K Choudhury
2003-11-01
The transversity distribution of quarks in a nucleon is one of the three fundamental distributions, that characterize nucleon’s properties in hard scattering processes at leading twist (twist 2). It measures the distribution of quark transverse spin in a nucleon polarized transverse to its (inﬁnite) momentum. It is a chiral-odd twist-two distribution function – gluons do not couple to it. Quarks in a nucleon/hadron are relativistically bound and transversity is a measure of the relativistic nature of bound quarks in a nucleon. In this work, we review some important aspects of this less familiar distribution function which has not been measured experimentally so far.
Hard probes of short-range nucleon-nucleon correlations
Energy Technology Data Exchange (ETDEWEB)
J. Arrington, D. W. Higinbotham, G. Rosner, M. Sargsian
2012-10-01
The strong interaction of nucleons at short distances leads to a high-momentum component to the nuclear wave function, associated with short-range correlations between nucleons. These short-range, high-momentum structures in nuclei are one of the least well understood aspects of nuclear matter, relating to strength outside of the typical mean-field approaches to calculating the structure of nuclei. While it is difficult to study these short-range components, significant progress has been made over the last decade in determining how to cleanly isolate short-range correlations in nuclei. We have moved from asking if such structures exist, to mapping out their strength in nuclei and studying their microscopic structure. A combination of several different measurements, made possible by high-luminosity and high-energy accelerators, coupled with an improved understanding of the reaction mechanism issues involved in studying these structures, has led to significant progress, and provided significant new information on the nature of these small, highly-excited structures in nuclei. We review the general issues related to short-range correlations, survey recent experiments aimed at probing these short-range structures, and lay out future possibilities to further these studies.
Low momentum nucleon-nucleon interaction and halo nuclei
Energy Technology Data Exchange (ETDEWEB)
Kuo, T.T.S.; Bogner, S.K. [SUNY at Stony Brook, Physics and Astronomy Department, Stony Brook, NY (United States)
2002-12-01
A low-momentum effective nucleon-nucleon (NN) interaction V{sub low-k} is derived by integrating out the high momentum modes of modern realistic NN potentials V{sub NN}. The Kuo-Lee-Ratcliff folded diagram method together with the Andreozzi-Lee-Suzuki iteration method are employed to carry out the integration. Our V{sub low-k} is confined within a cut-off momentum {lambda}. The deuteron binding energy, low-energy phase shifts and half-on-shell T-matrix of V{sub NN} are all preserved by V{sub low-k}. For {lambda} within {approx}2 fm{sup -1}, the V{sub low-k} derived from various NN potential models are very close to each other, although these models themselves are very different. V{sub low-k} is a smooth potential for {lambda} in the vicinity 2 fm{sup -1}, and appears to be suitable for being used directly as the shell model effective interaction, without first calculating the Brueckner G-matrix. Application of V{sub low-k} to halo nuclei is discussed. (author)
Realistic Low-Momentum Nucleon-Nucleon Potential
Kuo, T. T. S.; Bogner, S. K.; Coraggio, L.; Covello, A.; Itaco, N.
2002-04-01
A low-momentum nucleon-nucleon (NN) potential Vlow-k is derived from modern realistic NN potentials VNN by integrating out their high momentum modes. The Kuo-Lee-Ratcliff folded diagram method together with the Andreozzi-Lee-Suzuki iteration method is employed to carry out the integration. Our Vlow-k is confined within a cut-off momentum Λ, and it preserves the deuteron binding energy, low-energy phase shifts and low-momentum half-on-shell T-matrix of VNN. For Λ within ~ 2fm-1, the Vlow-k derived from various NN potential models are very close to each other, although these models themselves are very different. Vlow-k is a smooth potential for Λ in the vicinity 2fm-1, and appears to be suitable for being used directly as shell model effective interaction without first calculating the Brueckner G matrix. Preliminary shell-model calculations using Vlow-k have led to encouraging results.
Low Momentum Nucleon-Nucleon Interaction and Halo Nuclei
Kuo, T.; Bogner, S.
A low-momentum effective nucleon-nucleon (NN) interaction Vlow-k is derived by integrating out the high momentum modes of modern realistic NN potentials VNN. The Kuo-Lee-Ratcliff folded diagram method together with the Andreozzi-Lee-Suzuki iteration method are employed to carry out the integration. Our Vlow-k is confined within a cut-off momentum Λ. The deuteron binding energy, low-energy phase shifts and half-on-shell T-matrix of VNN are all preserved by Vlow-k. For Λ within ˜ 2 fm-1, the Vlow-k derived from various NN potential models are very close to each other, although these models themselves are very different. Vlow-k is a smooth potential for Λ in the vicinity 2 fm-1, and appears to be suitable for being used directly as the shell model effective interaction, without first calculating the Brueckner G-matrix. Application of Vlow-k to halo nuclei is discussed.
Testing Low Energy Theorems in Nucleon-Nucleon Scattering
Cohen, T D; Cohen, Thomas D.; Hansen, James M.
1999-01-01
Low energy theorems have been derived for the coefficients of the effective range expansion in s-wave nucleon-nucleon scattering valid to leading nontrivial order in an expansion based $Q$ counting, a scheme in which both $m_\\pi$ and $1/a$ (where $a$ is the scattering length) are treated as small mass scales. Previous tests of these theorems based on coefficients extracted from scattering data indicate a pattern of gross violations which suggested serious problems for the perturbative treatment of pions implicit in $Q$ counting. We discuss the possibility that uncertainties associated with extracting the coefficients from the scattering data make such tests invalid. Here we show that errors in the s-wave phase shift extractions are sufficiently small to test direct test predictions from $Q$ counting at next to leading order. In particular we show that there exist low energy theorems for the sum of all terms in the effective range expansion beyond the first two which allow for precise tests. These low energy t...
The nucleon-nucleon potential in the chromodielectric soliton model
Koepf, W.; Wilets, L.; Pepin, S.; Stancu, F.
The short and medium range parts of the nucleon-nucleon interaction are being studied in the framework of the chromodielectric soliton model. The model consists of current quarks, gluons in the abelian approximation, and a scalar sigma field which simulates the nonabelian interactions of the gluons and governs the medium through the dielectric function kappa(sigma). Absolute color confinement is effected by the vanishing of the dielectric in vacuum; this also removes the troublesome van der Waals problem. The authors distinguish between spatial confinement, which arises from the self energy of the quarks in medium (excluding MFA contributions), and color confinement which is effected through OGE in the MFA (including the corresponding self energy contributions). The static (adiabatic) energies are computed as a function of deformation (generalized bag separation) in a constrained MFA. Six quark molecular-type wave functions in all important space-spin-isospin-color configurations are included. The gluon propagator is solved in the deformed dielectric medium. The resultant Hamiltonian matrix is diagonalized. Dynamics are handled in the generator coordinate method, which leads to the Hill-Wheeler integral equation. In the present case, this yields a set of coupled equations corresponding to the various configurations. Although this can be approximated by a set of differential equations, they propose to solve the integral equations with some regularization scheme.
Accardi, Alberto
2016-01-01
I review recent progress in the extraction of unpolarized parton distributions in the proton and in nuclei from a unified point of view that highlights how the interplay between high energy particle physics and lower energy nuclear physics can be of mutual benefit to either field. Areas of overlap range from the search for physics beyond the standard model at the LHC, to the study of the non perturbative structure of nucleons and the emergence of nuclei from quark and gluon degrees of freedom, to the interaction of colored probes in a cold nuclear medium.
Medium Modification of Nucleon Properties in Skyrme Model
Khanna, F.; Rakhimov, A. M.; Musakhanov, M. M.; U. T. Yakhshiev(National University of Uzbekistan)
1996-01-01
A Skyrme type Lagrangian for a skyrmion imbedded in a baryon rich environment is proposed. The dependence of static nucleon properties and nucleon - nucleon tensor interaction on nuclear density is investigated.
Intrinsic charm content of the nucleon and charmness-nucleon sigma term
Duan, Shaorong; Saghai, B
2016-01-01
In the extended chiral constituent quark model, the intrinsic $c \\bar{c}$ content of the nucleon is investigated. The probabilities of the quark-antiquark components in the nucleon wave functions are calculated by taking the nucleon to be admixtures of three- and five-quark components, with the relevant transitions handled {\\it via} the $^{3}$P$_{0}$ mechanism. Predictions for the probability of the $c \\bar{c}$ in the nucleon wave function and the charmness-nucleon sigma term are presented. Our numerical results turn out to be consistent with the predictions from various other approaches reported in the literature.
Intrinsic charm content of the nucleon and charmness-nucleon sigma term
Duan, Shaorong; An, C. S.; Saghai, B.
2016-06-01
In the extended chiral constituent quark model, the intrinsic c c ¯ content of the nucleon is investigated. The probabilities of the quark-antiquark components in the nucleon wave functions are calculated by taking the nucleon to be admixtures of three- and five-quark components, with the relevant transitions handled via the 3P0 mechanism. Predictions for the probability of the c c ¯ in the nucleon wave function and the charmness-nucleon sigma term are presented. Our numerical results turn out to be consistent with the predictions from various other approaches reported in the literature.
On the nucleon-nucleon potential obtained from non-linear coupling
International Nuclear Information System (INIS)
The static limit of a pseudoscalar symmetric meson theory of nuclear forces is examined. The Born-Oppenheimer potential is determined for the case of two very heavy nucleons exchanging pseudoscalar isovector pions with non-linear coupling. It is found that the non-linear terms induced by the γ5 coupling are cancelled by the additional pion-nucleon coupling of the non-linear sigma model. The nucleon-nucleon potential thus obtained is the same as the Yukava potential except for strength at different separations between the two nucleons
Nucleon momentum and density distributions of nuclei
International Nuclear Information System (INIS)
In the framework of recently suggested density coherent fluctuations model the nucleon momentum and density distributions are examined. Nucleon momentum and density distributions are expressed in terms of the fluctuation's function, experimentally obtainable from the elastic electron-nuclei scattering. (author)
Towards a microscopic understanding of nucleon polarizabilities
Eichmann, Gernot
2016-01-01
We outline a microscopic framework to calculate nucleon Compton scattering from the level of quarks and gluons within the covariant Faddeev approach. We explain the connection with hadronic expansions of the Compton scattering amplitude and discuss the obstacles in maintaining electromagnetic gauge invariance. Finally we give preliminary results for the nucleon polarizabilities.
Orbital Angular Momentum in the Nucleon
Garvey, Gerald T.
2010-01-01
Analysis of the measured value of the integrated \\bar{d}-\\bar{u} asymmetry (Ifas = 0.147+-0.027) in the nucleon show it to arise from nucleon fluctuations into baryon plus pion. Requiring angular momentum conservation in these fluctuations shows the associated orbital angular momentum is equal to the value of the flavor asymmetry.
Spin–orbit correlations in the nucleon
International Nuclear Information System (INIS)
We investigate the correlations between the quark spin and orbital angular momentum inside the nucleon. Similarly to the Ji relation, we show that these correlations can be expressed in terms of specific moments of measurable parton distributions. This provides a whole new piece of information about the partonic structure of the nucleon
Nucleon Structure Functions from a Chiral Soliton
Weigel, H.(Physics Department, Stellenbosch University, Matieland 7602, South Africa); Gamberg, L.(Department of Physics, Penn State University-Berks, Reading, PA, 19610, U.S.A.); Reinhardt, H.
1996-01-01
Nucleon structure functions are studied within the chiral soliton approach to the bosonized Nambu-Jona-Lasinio model. The valence quark approximation is employed which is justified for moderate constituent quark masses ($\\sim$ 400 MeV) as the contribution of the valence quark level dominates the predictions of nucleon properties. As examples the unpolarized structure functions for the ${\
Interference Fragmentation Functions and the Nucleon's Transversity
Jaffe, R. L.; Jin, Xuemin; Tang, Jian
1997-01-01
We introduce twist-two quark interference fragmentation functions in helicity density matrix formalism and study their physical implications. We show how the nucleon's transversity distribution can be probed through the final state interaction between two mesons ($\\pi^+\\pi^-$, $K\\bar K$, or $\\pi K$) produced in the current fragmentation region in deep inelastic scattering on a transversely polarized nucleon.
Nucleon-XcJ Dissociation Cross Sections
Institute of Scientific and Technical Information of China (English)
冯又层; 许晓明; 周代翠
2002-01-01
Nucleon-XcJ dissociation cross sections are calculated in a constituent interexchange model in which quark-quark potential is derived from the Buchmüller-Tye quark-anti-quark potential. These new cross sections for dominant reaction channels depend on the centre-of-mass energy of the nucleon and the charmonium.
Etaprime interactions with nucleons and nuclei
Bass, Steven D
2015-01-01
We summarise recent progress in theory and experiment towards understanding etaprime meson interactions with nucleons and nuclei. Highlights include the production mechanism of etaprime mesons in proton-proton collisions close to threshold, the etaprime effective mass shift in nuclei and the determination of the etaprime-nucleon scattering length in free space.
Towards a Microscopic Understanding of Nucleon Polarizabilities
Eichmann, Gernot
2016-07-01
We outline a microscopic framework to calculate nucleon Compton scattering from the level of quarks and gluons within the covariant Faddeev approach. We explain the connection with hadronic expansions of the Compton scattering amplitude and discuss the obstacles in maintaining electromagnetic gauge invariance. Finally we give preliminary results for the nucleon polarizabilities.
Nucleon-nucleon theory and phenomenology. Progress report and renewal proposal
International Nuclear Information System (INIS)
Progress is outlined on five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction with the new dramatically altered ππ s-wave interaction and using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly, and determining which phases are given by theory at which energies; (4) the introduction of our K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated and verified permanent nucleon-nucleon data bank in the 0 to 1200 MeV range that can be used by all nucleon-nucleon researchers (or anyone else) via Telenet dial-in and by means of a published compendium
Theoretical Optical Potential Derived From Nucleon-Nucleon Chiral Potentials
Vorabbi, M; Giusti, C
2015-01-01
Background: Elastic scattering is probably the main event in the interactions of nucleons with nuclei. Even if this process has been extensively studied in the last years, a consistent description starting from microscopic two- and many-body forces is still missing. Purpose: In this work we study the domain of applicability of microscopic chiral potentials in the construction of an optical potential. Methods: We basically followed the KMT approach to build a microscopic complex optical potential and then we performed some test calculations on $^{16}$O at different energies. Results: Our conclusion is that a particular set of potentials (with spectral function regularization and a cut-off for the Lippmann-Schwinger equation at relatively high energies $\\sim 600$ MeV) has the best performances reproducing the scattering observables. Conclusions: Our work shows that building an optical potential within Chiral Perturbation Theory is a promising approach to the description of elastic proton scattering, in particul...
Low-energy pion double charge exchange and nucleon-nucleon correlations in nuclei
International Nuclear Information System (INIS)
Recent measurements of pion double-charge exchange (DCX) at energies 20 to 70 MeV are providing a new means for studying nucleon-nucleon correlations in nuclei. At these energies the nucleus is relatively transparent, allowing simpler theoretical models to be used in interpreting the data and leading to a clearer picture. Also the contribution to DCX of sequential charge-exchange scattering through the intermediate analog state is suppressed near 50 MeV and transitions through non-analog intermediate states become very important. Recent theoretical studies by several groups have shown that while transitions through the analog route involve relatively long nucleon-nucleon distances, those through non-analog intermediate states obtain nearly half their strength from nucleon pairs with less than 1 fermi separation. Thus DCX near 50 MeV is an excellent way to study short-range nucleon-nucleon correlations. 31 refs., 29 figs., 4 tabs
Low-energy pion double charge exchange and nucleon-nucleon correlations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leitch, M.J.
1989-01-01
Recent measurements of pion double-charge exchange (DCX) at energies 20 to 70 MeV are providing a new means for studying nucleon-nucleon correlations in nuclei. At these energies the nucleus is relatively transparent, allowing simpler theoretical models to be used in interpreting the data and leading to a clearer picture. Also the contribution to DCX of sequential charge-exchange scattering through the intermediate analog state is suppressed near 50 MeV and transitions through non-analog intermediate states become very important. Recent theoretical studies by several groups have shown that while transitions through the analog route involve relatively long nucleon-nucleon distances, those through non-analog intermediate states obtain nearly half their strength from nucleon pairs with less than 1 fermi separation. Thus DCX near 50 MeV is an excellent way to study short-range nucleon-nucleon correlations. 31 refs., 29 figs., 4 tabs.
Unitary three-body calculation of nucleon-nucleon scattering
International Nuclear Information System (INIS)
We calculate nucleon-nucleon elastic scattering phase parameters based on a unitary, relativistic, pion-exchange model. The results are highly dependent on the off-shell amplitudes of πN scattering. The isobar-dominated model for the P33 interaction leads to too small pion production rates owing to its strong suppression of off-shell pions. We propose to expand the idea of the Δ-isobar model in such a manner as to incorporate a background (non-pole) interaction. The two-potential model, which was first applied to the P11 partial wave by Mizutani and Koltun, is applied also to the P33 wave. Our phenomenological model for πN interaction in the P33 partial wave differs from the conventional model only in its off-shell extrapolation, and has two different variants for the πN → Δ vertex. The three-body approach of Kloet and Silbar is extended such that the background interactions can be included straightfowardly. We make detailed comparisons of the new model with the conventional one and find that our model adequately reproduces the 1D2 phase parameters as well as those of peripheral partial waves. We also find that the longitudinal total cross section difference ΔσL(pp → NNπ) comes closer to the data compared to Kloet and Silbar. We discuss about the backward pion propagation in the three-body calculation, and the Pauli-principle violating states for the background P11 interaction. (author)
The Spin Structure of the Nucleon
Pretz, Jörg
2007-01-01
This article reviews recent results on the spin structure of the nucleon from polarized deep inelastic lepton-nucleon scattering and polarized proton-proton scattering. For a description of the nucleon in terms of parton distribution functions (pdf) the knowledge of three basic distributions is needed: The relatively well known unpolarized pdfs, the helicity distributions and the transversity distributions. The latter two play an essential role in understanding the spin structure of the nucleon. New results on the gluon helicity distribution $\\Delta G(x)$ and the helicity distributions for strange and valence quarks are discussed. A first determination of the up to now unknown transversity distributions $\\Delta_{T}q(x)$ is presented. Finally results from deep virtual Compton scattering, giving access to the orbital angular momentum contribution of quarks to the nucleon spin, are discussed.
Pion production off the nucleon
Alam, M Rafi; Chauhan, Shikha; Singh, S K
2016-01-01
We have studied charged current neutrino/antineutrino induced weak pion production from nucleon. For the present study, contributions from $\\Delta(1232)$-resonant term, non-resonant background terms as well as contribution from higher resonances viz. $P_{11}$(1440), $D_{13}$(1520), $S_{11}$(1535), $S_{11}$(1650) and $P_{13}$(1720) are taken. To write the hadronic current for the non-resonant background terms, a microscopic approach based on SU(2) non-linear sigma model has been used. The vector form factors for the resonances are obtained from the helicity amplitudes provided by MAID. Axial coupling in the case of $\\Delta(1232)$ resonance is obtained by fitting the ANL and BNL $\
Nucleon Magnetic Moments and Electric Polarizabilities
Energy Technology Data Exchange (ETDEWEB)
W Detmold, B C Tiburzi, A Walker-Loud
2010-06-01
Electromagnetic properties of the nucleon are explored with lattice QCD using a novel technique. Focusing on background electric fields, we show how the electric polarizability can be extracted from nucleon correlation functions. A crucial step concerns addressing contributions from the magnetic moment, which affects the relativistic propagation of nucleons in electric fields. By properly handing these contributions, we can determine both magnetic moments and electric po larizabilities. Lattice results from anisotropic clover lattices are presented. Our method is not limited to the neutron; we show results for the proton as well.
Orbital angular momentum in the nucleons
Lorcé, Cédric
2014-01-01
In the last decade, it has been realized that the orbital angular momentum of partons inside the nucleon plays a major role. It contributes significantly to nucleon properties and is at the origin of many asymmetries observed in spin physics. It is therefore of paramount importance to determine this quantity if we want to understand the nucleon internal structure and experimental observables. This triggered numerous discussions and controversies about the proper definition of orbital angular momentum and its extraction from experimental data. We summarize the present situation and discuss recent developments in this field.
Nucleon wave function from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Warkentin, Nikolaus
2008-04-15
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
Quark model for kaon nucleon scattering
Indian Academy of Sciences (India)
Ahmed Osman
2011-12-01
Kaon nucleon elastic scattering is studied using chiral (3) quark model including antiquarks. Parameters of the present model are essentially based on nucleon–nucleon and nucleon–hyperon interactions. The mass of the scalar meson is taken as 635 MeV. Using this model, the phase shifts of the and partial waves of the kaon nucleon elastic scattering are investigated for isospins 0 and 1. The results of the numerical calculations of different partial waves are in good agreement with experimental data.
Nucleon wave function from lattice QCD
International Nuclear Information System (INIS)
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
Proton and neutron polarized targets for nucleon-nucleon experiments at SATURNE II
International Nuclear Information System (INIS)
A SATURNE polarized target has been used for nucleon-nucleon elastic scattering and transmission experiments for 15 years. The polarized proton target is a 70 cm3 cartridge loaded with Pentanol-2. For polarized neutron target, two cartridges loaded with 6LiD and 6LiH are set in the refrigerator and can be quickly inserted in the beam. First experiments using 6Li products in quasielastic pp or pn analyzing power measurements are compared with the same observables measured in a free nucleon-nucleon scattering using polarized proton targets. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon-nucleon scattering is shown for different targets. (author)
Nucleon-nucleon interaction and the quark model
International Nuclear Information System (INIS)
The NN phase shifts are calculated using the quark model with a QCD inspired quark-quark force. The short range part of the NN force is given by quark and gluon exchange. The long range part is described by π and σ-meson exchange. The data fitted in the model are five values connected with three quarks only: the nucleon mass, the Δ mass, the root mean square radius of the charge distribution of the proton including the pion cloud, the π-N and the σ-N coupling constant at zero momentum transfer. The 1S and 3S phase shifts are nicely reproduced. The short range repulsion is decisively influenced by the node in the [42]r relative wave function. Very important is the colour magnetic quark-quark force which enlarges the [42]r admixture. In the OBEP's the short range repulsion is connected with the exchange of the ω-meson. But to reproduce the short range repulsion one had to blow up the ω-N coupling constant by a factor 2 to 3 compared to flavour SU3. With quark and gluon exchange the best fit to the ω-N coupling constant lies close to the SU3 flavour value. This fact strongly supports the notion that the real nature of the short range repulsion of the NN interaction have been found
High energy nucleon incident optical potential by relativistic impulse approximation
International Nuclear Information System (INIS)
The optical potentials by relativistic impulse approximation (RIA) are utilized for the high energy nucleon incidence. The nucleon-nucleon scattering amplitudes are derived from the phase shift and parametrized as a function of the incident nucleon energy. The optical potential by RIA reproduces the experimental data. (author)
International Nuclear Information System (INIS)
The integral characteristics of the potential distribution in nuclei, namely the volume integrals, moments and mean square radii are studied in the framework of the semimicroscopic approach to the interaction of low energy nucleons with nuclei on the base of the exchange nucleon-nucleon correlations and the density dependence of effective forces. The ratio of the normalized multipole moments of potential and matter distributions is investigated. The energy dependence of the integral characteristics is analyzed. 15 refs.; 2 tabs
Connection of Kukulin's nucleon-nucleon deep potential with realistic repulsive core interactions
International Nuclear Information System (INIS)
The on-shell equivalence of the deep quantum-chromodynamically motivated realistic nucleon-nucleon interaction recently proposed by Kukulin et al. with more conventional repulsive-core forces is investigated by eliminating its unphysical deeply bound states, while preserving its scattering properties and the binding energy of the deuteron. The resulting interaction, which is built both in the singlet and triplet channels, displays a r-2 singular repulsive core followed by a shallow attraction of intermediate range, in good semiquantitative agreement with existing realistic nucleon-nucleon interactions. (orig.)
Pion photoproduction on the nucleon at threshold
International Nuclear Information System (INIS)
Electric dipole amplitudes of pion photoproduction on the nucleon at threshold have been calculated in the framework of the chiral bag model. Our results are in good agreement with the existing experimental data
Probing nucleon structure on the lattice
International Nuclear Information System (INIS)
The QCDSF/UKQCD Collaboration has an ongoing program to calculate nucleon matrix elements with two flavours of dynamical O(a) improved Wilson fermions. Here we present recent results on the electromagnetic form factors, the quark momentum fraction left angle x right angle and the first three moments of the nucleon's spin-averaged and spin-dependent generalised parton distributions, including preliminary results with pion masses as low as 320 MeV. (orig.)
Gauge-Invariant Decomposition of Nucleon Spin
International Nuclear Information System (INIS)
I introduce a gauge-invariant decomposition of the nucleon spin into quark helicity, quark orbital, and gluon contributions. The total quark (and hence the quark orbital) contribution is shown to be measurable through virtual Compton scattering in a special kinematic region where single quark scattering dominates. This deeply virtual Compton scattering has much potential to unravel the quark and gluon structure of the nucleon. copyright 1997 The American Physical Society
Probing nucleon structure on the lattice
International Nuclear Information System (INIS)
The QCDSF/UKQCD collaboration has an ongoing program to calculate nucleon matrix elements with two flavours of dynamical O(a) improved Wilson fermions. Here we present recent results on the electromagnetic form factors, the quark momentum fraction left angle x right angle and the first three moments of the nucleon's spin-averaged and spin-dependent generalised parton distributions, including preliminary results with pion masses as low as 320 MeV. (orig.)
Probing nucleon structure on the lattice
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Haegler, P. [Technische Univ. Muenchen, Garching (Germany). Physik-Department, Inst. fuer Theoretische Physik T39; Horsley, R. [Edinburgh Univ. (GB). School of Physics] (and others)
2006-08-15
The QCDSF/UKQCD collaboration has an ongoing program to calculate nucleon matrix elements with two flavours of dynamical O(a) improved Wilson fermions. Here we present recent results on the electromagnetic form factors, the quark momentum fraction left angle x right angle and the first three moments of the nucleon's spin-averaged and spin-dependent generalised parton distributions, including preliminary results with pion masses as low as 320 MeV. (orig.)
The nucleon-nucleon interaction in the framework of the boson exchange model
International Nuclear Information System (INIS)
The aim of this thesis was the description of the nucleon-nucleon interaction in a microscopically founded model. For this the description of the 2-nucleon problem by an interacting 2-nucleon-pion system was presented. The starting point of our description was a relativistic eigenvalue equation for the system of mesons and two baryons. The interaction of the baryons with the mesons was described by interaction Hamiltonians. By the elimination of antinucleon states by means of a unitary tansformation (Foldy-Wouthuysen transformation) the interaction Hamiltonians for nucleons could be generated for the field-theoretical Lagrangian densities. The Hamiltonians for resonant baryon states were obtained by means of a simplified procedure from the corresponding Lagrangian densities. Because the determination of Lagrangian densities is not unique, for the pion-nucleon coupling two alternative Lagrangian densities were allowed. For the interaction of positive-energy nucleonic states these two coupling yield nearly equal results; the production or annihilation of negative-energy nucleon states (antiparticles) the predictions however are very different. (orig./HSI)
Study of the ground-state energy of 40Ca with realistic nucleon-nucleon potentials
Coraggio, L; Gargano, A; Itaco, N; Kuo, T T S
2006-01-01
We have calculated the ground-state energy of the doubly-magic nucleus 40Ca within the framework of the Goldstone expansion using the CD-Bonn nucleon-nucleon potential. The short-range repulsion of this potential has been renormalized by integrating out its high-momentum components so as to derive a low-momentum potential V-low-k defined up to a cutoff momentum Lambda. A simple criterion has been employed to establish a connection between this cutoff momentum and the size of the two-nucleon model space in the harmonic oscillator basis. This model-space truncation approach provides a reliable way to renormalize the free nucleon-nucleon potential preserving its many-body physics. Our results evidence the role of the 3p-3h and 4p-4h excitations in the description of the ground state of 40Ca.
Parity violation in nuclei: studies of the weak nucleon-nucleon interaction
International Nuclear Information System (INIS)
The Weinberg-Salam Unified Model of weak and electromagnetic interactions has been very successful in explaining parity violation and neutral current effects in neutrino-nucleon, electron-nucleon and neutrino-electron interactions. A wide variety of nuclear physics parity violation experiments are in progress to measure effects of the weak nucleon-nucleon interaction in few nucleon systems and certain heavier nuclei where enhancements are expected. The current status of these experiments will be reviewed, including details of an experiment at Chalk River to search for parity violation in the photodisintegration of deuterium and an extension of our previous measurements of parity mixing in 21Ne. The interpretation of results in terms of basic models of the weak interaction will be discussed. (Auth)
Subthreshold pion production: Nucleon-nucleon single collision vs. co-operative mechanisms
International Nuclear Information System (INIS)
Various reaction mechanisms proposed to explain the pion production at ''subthreshold'' energies (below 290 MeV/A) are examined. They range from the nucleon-nucleon single collision mechanism to a co-operative multi-nucleon process. With a shell model prescription for the initial state energies the single collision picture can not explain the data. The participation of many nucleons in the pion production process appears to be necessary. We present a statistical model where the co-operative action of several of the target and projectile nucleons in the pion production process is invoked. We also consider the formation of the fragments in the final channel alongside the produced pion. Calculations performed within the model provide a good overall description of the experimental data over a wide range of beam energies and masses of the participating nuclei. Fragment formation in the final channel is seen to be vital to understand the experimental data within our model. (orig.)
Time-reversal-invariance-violating nucleon-nucleon potential in the 1/N_c expansion
Samart, Daris; Schindler, Matthias R; Phillips, Daniel R
2016-01-01
We apply the large-$N_c$ expansion to the time-reversal-invariance-violating (TV) nucleon-nucleon potential. The operator structures contributing to next-to-next-to-leading order in the large-$N_c$ counting are constructed. For the TV and parity-violating case we find a single operator structure at leading order. The TV but parity-conserving potential contains two leading-order terms, which however are suppressed by 1/$N_c$ compared to the parity-violating potential. Comparison with phenomenological potentials, including the chiral EFT potential in the TV parity-violating case, leads to large-$N_c$ scaling relations for TV meson-nucleon and nucleon-nucleon couplings.
Isospin Mixing in the Nucleon and 4He and the Nucleon Strange Electric Form Factor
International Nuclear Information System (INIS)
In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in 4He(e-vector,e')4He experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4He. We examine this issue in the present Letter. Isospin admixtures in the nucleon are determined in chiral perturbation theory, while those in 4He are derived from nuclear interactions, including explicit ISB terms. A careful analysis of the model dependence in the resulting predictions for the nucleon and nuclear ISB contributions to the asymmetry is carried out. We conclude that, at the low momentum transfers of interest in recent measurements reported by the HAPPEX Collaboration at Jefferson Lab, these contributions are of comparable magnitude to those associated with strangeness components in the nucleon electric form factor
Isoscaling Parameter α as a Possible Probe of Medium Effect of Nucleon-Nucleon Cross Section
Institute of Scientific and Technical Information of China (English)
LIU Jian-Ye; HAO Huan-Feng; XING Yong-Zhong; ZUO Wei; LEE Xi-Guo
2007-01-01
The medium effect of nucleon-nucleon cross section σmedNN(αm) on the isoscaling parameter α is investigated for two central nuclear reactions 40 Ca+40 Ca, 60 Ca+6o Ca within isospin-dependent quantum molecular dynamics at beam energies from 40 to 50 MeV/nucleon. It is found that there is the very obvious medium effects of nucleonnucleon cross section σmedNN(αm) on the isoscaling parameters α. In this case the isoscaling parameter α is a possible probe of the medium effect of nucleon-nucleon cross section σmedNN(αm) in the heavy ion collisions. The mechanism of the above-mentioned properties is studied and discussed.
The spin structure of the nucleon
International Nuclear Information System (INIS)
This document describes the recent experimental results on the spin structure of the nucleon obtained with the electron accelerator Thomas Jefferson National Facility (Jefferson Lab), Virginia. We first discuss the goal of studying the nucleon spin structure and give the basis and phenomenology of high energy lepton scattering. Then, we discuss with some details a few sum rules concerning the spin structure of the nucleon. Those are important tools for studying the nucleon spin structure at Jefferson Lab. We then describe the present experimental situation and analyze the results. We have been able to determine an effective coupling constant for the strong interaction for any regime of quantum chromodynamics which proves that QCD is an approximately conformal theory. We conclude on the perspectives for this field of research, in particular with the 12 GeV energy upgrade of Jefferson Lab. The top priority will be the measurement of generalised parton distributions. The only issue that will stay misunderstood is the role of the very low x domain on the spin structure of the nucleon
Scalar and Pseudoscalar Higgs Couplings with Nucleons
International Nuclear Information System (INIS)
The estimation of the cross sections of certain dark matter interactions with nuclei requires a correct evaluation of the couplings between the scalar or pseudoscalar Higgs boson and the nucleons. Progress has been made in two aspects relevant to this study in the past few years. First, recent lattice calculations show that the strange-quark sigma term σs and the strange-quark content in the nucleon are much smaller than what are expected previously. However, in view of the conflict between lattice and experimental results for the pion-nucleon sigma term σπN, the quark sigma terms σu,d,s are still not well determined. Second, the pseudoscalar Higgs coupling with the nucleon is customarily expressed in terms of the axial-vector couplings gAa(a=0,3,8) or the quark spin components Δu,Δd and Δs. Lattice calculations, semi-inclusive deep inelastic scattering data, and the small ΔG/G obtained by RHIC, COMPASS and HERMES all indicate a smaller Δs=O(−0.02∼−0.03), which in turn implies sizable SU(3) breaking effects in the determination of gA8 and gA0. We re-evaluate the relevant nucleon matrix elements and compute the scalar and pseudoscalar couplings of the proton and neutron
Ab initio many-body calculations of nucleon-4He scattering with three-nucleon forces
Hupin, Guillaume; Navrátil, Petr; Quaglioni, Sofia; Calci, Angelo; Roth, Robert
2013-01-01
We extend the ab initio no-core shell model/resonating-group method to include three-nucleon (3N) interactions for the description of nucleon-nucleus collisions. We outline the formalism, give algebraic expressions for the 3N-force integration kernels, and discuss computational aspects of two alternative implementations. The extended theoretical framework is then applied to nucleon-4He scattering using similarity-renormalization-group (SRG) evolved nucleon-nucleon plus three-nucleon potentials derived from chiral effective field theory. We analyze the convergence properties of the calculated phase shifts and explore their dependence upon the SRG evolution parameter. We include up to six excited states of the 4He target and find significant effects from the inclusion of the chiral 3N force, e.g., it enhances the spin-orbit splitting between the 3/2- and 1/2- resonances and leads to an improved agreement with the phase shifts obtained from an accurate R-matrix analysis of the five-nucleon experimental data. We ...
Scalar-isoscalar meson exchange in the calculation of the nucleon-nucleon interaction
International Nuclear Information System (INIS)
We provide a unified description of (i) scalar-isoscalar exchange in the nucleon-nucleon interaction, (ii) the pion-nucleon sigma term, and (iii) the scalar form factor of the nucleon. Our analysis requires that we specify a parameter that appears in the description of a nucleon valence-quark open-quotes core.close quotes Other parameters are fixed either by our analysis of the Nambu endash Jona-Lasinio model, or with reference to a recent lattice simulation of QCD in which the scalar form factor of the nucleon was calculated. We find that our model has some predictive power. Once the parameters are fixed, we find that we reproduce the values of the scalar form factor of the nucleon, as determined in the lattice simulation. We also predict the strength of the scalar-isoscalar NN potential for the particular one-boson-exchange model considered here, where the effects of (virtual) Δ excitation are treated in an explicit fashion. However, the overall strength of the force obtained in this work is sensitive to the approximations used in the calculation. copyright 1997 The American Physical Society
Description of a nucleon in nuclear matter
International Nuclear Information System (INIS)
The nonlinear cloudy bag model, CBM, is generalized to describe a nucleon in nuclear matter at various densities ρ and temperatures T. The influence of the nuclear medium on the bag-nucleon in the framework of CBM is due to the modification of the equation describing the CBM pion field π. These changes are accounted for in the CBM by including in the CBM lagrangian the pion polarization operator π(ρ,T). The free pion propagator D is replaced in a nuclear medium by D(ρ,T). The changing of the pion field π and propagator D leads via the CBM equations to the modification of the bag size R and quark momentum p, determined simultaneously from these equations, and then to modifications of other bag-nucleon characteristics: the total energy E, r.m.s. radii, magnetic moment μ, polarizability α and so on, which all are expressed as the expectation values of the corresponding operators in the bag-nucleon state. The quantity π(ρ,T) was studied in the works whose results are used in this investigation. The nucleon size R in the nuclear matter at normal density ρo and zero temperature decreases by 5% and the quarks momentum p also decreases, however, insignificantly, by 1-2%. On the other hand, the values of the r.m.s. radii increases by 15% for a proton and by 100% for a neutron. The author has also found that the polarizability of a nucleon in nuclear matter is roughly two times as much as in free space
Three-nucleon reactions with chiral dynamics*
Directory of Open Access Journals (Sweden)
Witała H.
2014-03-01
Full Text Available Faddeev calculations using the chiral three-nucleon force at next-to-next-to-next-to-leading-order show that this force is not able to provide an explanation for the low-energy Ay puzzle. Also the large discrepancies between data and theory for the symmetric-space-star and for the neutron-neutron quasi-free-scattering cross sections in low energy neutron-deuteron breakup cannot be explained by that three-nucleon force. The discrepancy for the neutron-neutron quasi-free-scattering cross section seems to require a modification of the 1S0 neutron-neutron force.
Three-nucleon reactions with chiral dynamics*
Witała H.; Golak J.; Skibiński R.; Topolnicki K.
2014-01-01
Faddeev calculations using the chiral three-nucleon force at next-to-next-to-next-to-leading-order show that this force is not able to provide an explanation for the low-energy Ay puzzle. Also the large discrepancies between data and theory for the symmetric-space-star and for the neutron-neutron quasi-free-scattering cross sections in low energy neutron-deuteron breakup cannot be explained by that three-nucleon force. The discrepancy for the neutron-neutron quasi-free-scattering cross sectio...
On the nucleon effective mass role to the high energy proton spallation reactions
Santos, B. M.; Pinheiro, A. R. C.; Gonçalves, M.; Duarte, S. B.; Cabral, R. G.
2016-04-01
We explore the effect of the nucleon effective mass to the dynamic evolution of the rapid phase of proton-nucleus spallation reactions. The analysis of the relaxation time for the non-equilibrium phase is studied by variations in the effective mass parameter. We determine the final excitation energy of the hot residual nucleus at the end of cascade phase and the de-excitation of the nuclear system is carried out considering the competition of particle evaporation and fission processes. It was shown that the excitation energy depends of the hot compound residual nucleus at the end of the rapid phase on the changing effective mass. The multiplicity of particles was also analyzed in cascade and evaporation phase of the reaction. The use of nucleon effective mass during cascade phase can be considered as an effect of the many-body nuclear interactions not included explicitly in a treatment to the nucleon-nucleon interaction inside the nucleus. This procedure represents a more realistic scenario to obtain the neutron multiplicity generated in this reaction, which is a benchmark for the calculation of the neutronic in the ADS reactors.
Nucleon-nucleon interaction with a flat bottom linear confinement potential in the quark model
International Nuclear Information System (INIS)
Nucleon-nucleon interaction is studied in the non-relativistic quark model with a flat bottom linear confinement potential. The results are consistent with the calculated ones from the lattice quantum chromodynamics. The quark-quark interaction also consists of those caused by the one gluon exchange and the one pion exchange. The phenomenological sigma meson exchange between two nucleons is also included to fit the S-wave N-N scattering data. The calculated NN channel S-wave phase shifts show that the flat bottom linear confinement potential can provide part of the medium range attraction
The nucleon-nucleon interaction and the nuclear many-body problem
International Nuclear Information System (INIS)
In this review we wish to relate effective forces in nuclear matter and in nuclei back to the interaction between two isolated nucleons. Low-brow meson theory is used to derive the nucleon-nucleon interaction, with dispersion theoretical calculations as a guide, and a certain amount of phenomenology to pin down the parameters. A chiral picture is in the back of our mind, but since the main approach here is a semi-phenomenological one, chiral invariance is not developed in detail. (orig.)
The nucleon-nucleon interaction and the nuclear many-body problem
International Nuclear Information System (INIS)
In this review we wish to relate effective forces in nuclear matter and in nuclei back to the interaction between two isolated nucleons. Low-brow meson theory is used to derive the nucleon-nucleon interaction, with dispersion theoretical calculations as a guide, and a certain amount of phenomenology to pin down the parameters. A chiral picture is in the back of our mind, but since the main approach here is a semi-phenomenological one, chiral invariance is not developed in detail. (orig./WL)
Precise Determination of Charge Dependent Pion-Nucleon-Nucleon Coupling Constants
Perez, R Navarro; Arriola, E Ruiz
2016-01-01
We undertake a covariance error analysis of the pion-nucleon-nucleon coupling constants from the Granada-2013 np and pp database comprising a total of 6713 scattering data. Assuming a unique pion-nucleon coupling constant we obtain $f^2=0.0761(3)$. The effects of charge symmetry breaking on the $^3P_0$, $^3P_1$ and $^3P_2$ partial waves are analyzed and we find $f_{p}^2 = 0.0759(4)$, $f_{0}^2 = 0.079(1)$ and $f_{c}^2 = 0.0763(6)$ with minor correlations among the coupling constants. We successfully test normality for the residuals of the fit.
The Glauber approach in perturbative QCD: nucleon case
International Nuclear Information System (INIS)
We investigate the shadowing corrections for the nucleon gluon distribution predicted from Glauber (Mueller) approach in perturbative QCD. This work is a digest for the nucleon case of the extended work prior presented by the authors
Three-nucleon scattering by using chiral perturbation theory potential
International Nuclear Information System (INIS)
Three-nucleon scattering problems are studied by using two-nucleon and three-nucleon potentials derived from chiral perturbation theory. The three-nucleon term is shown to appear in the effective potential of the rank of next-to-next-to-leading order (NNLO). New three-nucleon forces are taken into consideration in addition to the conventional Fujita-Miyazawa (FM) type three-nucleon potential. Two-nucleon potential of the chiral perturbation theory is as precise as the conventional ones in low energy region. The FM type three-nucleon force which explains Sagara discrepancy in high energy region is introduced automatically. Concerning the Ay puzzle, the results seems to behave as if the puzzle has been solved at the level of NLO, but at the NNLO (without three-nucleon force) level the result is similar to the cases of conventional potential indicating the need of three-nucleon force. In contrast to the FM type three-nucleon force, five free parameters exist in the new D and E type three-nucleon forces introduced by the NNLO, but they are reduced to two independent parameters by antisymmetrization, which are found to be sensitive to the coupling energy of tritons and to the nd scattering length (spin doublet state). Parameters determined from them cannot give satisfactory answer to the Ay puzzle. It seems, however, too hasty to conclude that Ay puzzle cannot be solved by the chiral perturbation theory. (S. Funahashi)
Difference in leptoproduction of hidden flavors on nuclei and nucleons
International Nuclear Information System (INIS)
On the basis of the nucleon colour oscillations in a nucleus an increase (∼ 102 per nucleon) of the Ψ-meson leptoproduction yield on heavy nuclei (Fe, etc.) is predicted as compared with that on single nucleons. When hidden beauty is leptoproduced, the nuclear enhancement effect may not occur up to ∼ 200 GeV
Gamma Matrix Expansion of the Bethe-Salpeter Equation for Nucleon-Nucleon System
Kinpara, Susumu
2016-01-01
For the coefficients of the amplitude a set of simultaneous equations is derived in momentum space. By the auxiliary conditions they are equivalent to nonrelativistic equations and suitable for the investigation of two-nucleon system.
Hadron production in nucleon-nucleon collisions at 200 GeV/c - a compilation
International Nuclear Information System (INIS)
Data on stable hadron production in p+p and p+n interactions at 200 GeV/c are reviewed. Methods to construct missing data in the p+p, p+n, and n+n interactions are derived from charge symmetry and charge, baryon and strangeness conservation, and used to yield nucleon-nucleon interaction results. These may be useful for evaluating nucleus-nucleus collision measurements in terms of enhancements and suppressions. Parameterizations of pt2 and rapidity distributions are presented to provide yields in acceptance cuts for comparisons to nucleus-nucleus data. As an example the derived nucleon-nucleon multiplicities are reduced to the acceptances of the NA-35 CERN S+S experiment. (orig.)
Nucleon-nucleon scattering at small angles, measured at ANKE-COSY
Bagdasarian, Z.
2016-03-01
The most accepted approach to describe nucleon-nucleon (NN) interaction is the partial wave analysis (PWA), which translates various experimental observables to the common language of the partial waves. The reliable analysis relies not only on the quality experimental data, but also on the measurements of scattering observables over preferably the full angular range. Small angle scattering has been measured for six beam energies between 0.8 and 2.4 GeV using polarized proton beam incident on both proton and deuteron unpolarized targets at COSY-ANKE. This proceeding will report on the published and preliminary results for both pp and pn scattering from this and other recent experiments at ANKE. This study aims to provide the valuable observables to the SAID group in order to improve the phenomenological understanding of the nucleon-nucleon interaction.
All the states of the nucleon. Nucleon spectroscopy through the production of mesons
International Nuclear Information System (INIS)
The photoproduction of mesons on the nucleon gives a direct access to its spectroscopy and is a promising way for the study of the structure of the nucleon. The GRAAL experiment uses a tagged and polarized photon beam produced through the Compton diffusion of laser photons on the electrons circulating in the ESRF storage ring. The combination of this photon beam and an efficient detection system has allowed a series of measurements concerning the photoproduction of light mesons on the proton and on the neutron. The first 4 chapters are dedicated to the nucleon spectroscopy: the nucleon models and their consequences on the excited levels are recalled, the experimental technique used is described and the difficulties due to the extraction of relevant data are presented. Highly accurate measurements of cross-sections, Σ asymmetry beams and resonance parameters have been performed. The last part is dedicated to the principle of the measurement of the electric dipole momentum of the neutron. (A.C.)
Institute of Scientific and Technical Information of China (English)
XING Yong-Zhong; HAO Huan-Feng; LIU Xiao-Bin; FANG Yu-Tian; LIU Bao-Yi
2007-01-01
@@ Influences of the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction (MDI) on the isotope scaling are investigated by using the isospin-dependent quantum molecular dynamics model (IQMD). The results show that both the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction affect the isoscaling parameters appreciably and independently. The influence caused by the isospin dependence of two-body collision is relatively larger than that from the MDI in the mean field. Aiming at exploring the implication of isoscaling behaviour, which the statistical equilibrium in the reaction is reached, the statistical properties in the mass distribution and the kinetic energy distribution of the fragments simulated by IQMD are presented.
Constituent quark description of nucleon structure
International Nuclear Information System (INIS)
Nucleon structure functions are calculated within the constituent quark in the leading order. The results compare well with the experimental data for entire range of kinematics in x and Q2and with the next - to - leading order calculation of GRV
Scattering problem for four-nucleon system
International Nuclear Information System (INIS)
The Faddeev-Osborn equation for the nucleon-trinucleon elastic scattering is studied by generalizing the exact approach of the boson-triboson case. The Schmidt expansion theorem is used to express the 3+1 and 2+2-subamplitudes at energies in the continuous spectrum region as an infinite series of separable terms. Employing the pole term decomposition for these subamplitudes expressed in terms of the Schmidt expansion we can define, in conformity with the Faddeev residue prescription, respective four-nucleon amplitudes that describe elastic/rearrangement, partial breakup and full breakup scattering processes. Acquired simultaneous equations of these amplitudes take the form of multichannel two-particle Lippmann-Schwinger type, which we call Faddeev-Osborn equation. Assuming as an s-wave spin-dependent, rank two separable potential of the Tabakin type for the two-particle interaction, are derived the Faddeev-Osborn equation for the nucleon-trinucleon elastic scattering which includes spin and iso-spin analysis and angular momentum decomposition. To treat singularities appeared in our equation, the numerical calculation is performed in the frame-work of the complex-valued analysis by introducing contour rotation method. The N-T elastic scattering amplitude for a S=T=0, L=0 state of a four-nucleon system is obtained numerically in the incident laboratory energy region of 0.01 - 6.0 Mev, including only 1=0 state for the 3+1-subamplitude. (author)
Nucleonic guages in Philippine industry: current applications
International Nuclear Information System (INIS)
Nucleonic gauges have been used in Philippine industries for more than thirty years. There are now close to 500 units being used to determine and/or control level, density, concentration, weight and other parameters. Gauges are found in the food, cement, mineral processing, steel, paper, cigarette, plastic and construction industries. (author)
The nucleon wave function at the origin
Gruber, Michael
2010-01-01
We calculate the next-to-leading order perturbative corrections to the SVZ sum rules for the coupling f_N, the nucleon leading twist wave function at the origin. The results are compared to the established Ioffe sum rules and also to lattice QCD simulations.
Estimates of the Nucleon Tensor Charge
Gamberg, L P; Gamberg, Leonard; Goldstein, Gary R.
2001-01-01
Like the axial vector charges, defined from the forward nucleon matrix element of the axial vector current on the light cone, the nucleon tensor charge, defined from the corresponding matrix element of the tensor current, is essential for characterizing the momentum and spin structure of the nucleon. Because there must be a helicity flip of the struck quark in order to probe the transverse spin polarization of the nucleon, the transversity distribution (and thus the tensor charge) decouples at leading twist in deep inelastic scattering, although no such suppression appears in Drell-Yan processes. This makes the tensor charge difficult to measure and its non-conservation makes its prediction model dependent. We present a different approach. Exploiting an approximate SU(6)xO(3) symmetric mass degeneracy of the light axial vector mesons (a1(1260), b1(1235) and h1(1170)) and using pole dominance, we calculate the tensor charge. The result is simple in form and depends on the decay constants of the axial vector me...
Pion photoproduction in nucleons at low energies
International Nuclear Information System (INIS)
A new semiphenomenological analysis of the multipoles for pion photoproduction from nucleons, in the region of the first π-N resonance is presented. Through an energy dependent model, multipoles with isospin 1/2 and 3/2 and total angular momentum J < = 3/2 are determined. (Author)
Hyperspherical calculations for four-nucleon systems
International Nuclear Information System (INIS)
We develop hyperspherical calculations on the bound states of four-nucleon systems and particularly the fundamental level and the first 0+ excited states. With neglect of the Coulomb effect, we analyze the convergence of the optimal subset expansion for the binding energies calculated for central or realistic potentials. 35 refs
On the nucleon momentum distribution in nuclei
International Nuclear Information System (INIS)
A model of nuclear density ''coherentum fluctons'' (an alternative to Brueckner theory) is constructed with the aim of theoretically strict explanation of high moment components in nucleon momentum distribution that are responsible for the particle inclusive production. The formula of momentum distribution obtained within this model does not contain free parameters and high momentum components appear in a natural way
Study of excited nucleons and their structure
Energy Technology Data Exchange (ETDEWEB)
Burkert, Volker D. [JLAB, Newport News, VA (United States)
2014-01-01
Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.
The Flavor Asymmetry of the Nucleon Sea
Steffens, F. M.; Thomas, A W
1996-01-01
We re-examine the effects of anti-symmetry on the anti-quarks in the nucleon sea arising from gluon exchange and pion exchange between confined quarks. While the effect is primarily to suppress anti-down relative to anti-up quarks, this is numerically insignificant for the pion terms.
Scattering of vector mesons off nucleons
International Nuclear Information System (INIS)
We construct a relativistic and unitary approach to 'high' energy pion- and photon-nucleon reactions taking the πN, πΔ, ρN, ωN, ηN, K Λ, KΣ final states into account. Our scheme dynamically generates the s- and d-wave nucleon resonances N(1535), N(1650) and N(1520) and isobar resonances Δ(1620) and δ(1700) in terms of quasi-local interaction vertices. The description of photon-induced processes is based on a generalized vector-meson dominance assumption which directly relates the electromagnetic quasi-local 4-point interaction vertices to the corresponding vertices involving the ρ and ω fields. We obtain a satisfactory description of the elastic and inelastic pion- and photon-nucleon scattering data in the channels considered. The resulting s-wave ρ- and ω-nucleon scattering amplitudes are presented. Using these amplitudes we compute the leading density modification of the ρ and ω mass distributions in nuclear matter. We find a repulsive mass shift for the ω meson at small nuclear density but predict considerable strength in resonance-hole like ω-meson modes. Compared to previous calculations our result for the ρ-meson spectral function shows a significantly smaller in-medium effect. This reflects a not too large coupling strength of the N(1520) resonance to the ρN channel. (orig.)
Photo-production of Nucleon Resonances and Nucleon Spin Structure Function in the Resonance Region
Qing, D; Qing, Di; Schmidt, Ivan
2002-01-01
The photo-production of nucleon resonances is calculated based on a chiral constituent quark model including both relativistic corrections H{rel} and two-body exchange currents, and it is shown that these effects play an important role. We also calculate the first moment of the nucleon spin structure function g1 (x,Q^2) in the resonance region, and obtain a sign-changing point around Q^2 ~ 0.27 {GeV}^2 for the proton.
New relations in lepton-nucleon scattering independent of the nucleon structure
International Nuclear Information System (INIS)
New relations in deep inelastic and (quasi-)elastic scattering of polarized electrons and positrons (μ±-mesons) on non-polarized nucleons have been obtained. They connect cross sections with standard model parameters and are independent of the structure functions and form factors of the nucleon. A well known example is the Paschos-Wolfenstein relation in (ν-bar)N-scattering. 6 refs
Novel three-nucleon-force terms in the three-nucleon system
International Nuclear Information System (INIS)
We include to specific three-nucleon-force terms of pion-range-short-range form in our momentum-space calculations for the three-nucleon continuum. These two terms are expected by chiral perturbation theory to be non-negligible. We study the effects of these terms in elastic neutron-deuteron scattering and pay special attention to the neutron vector-analyzing power Ay. (author)
Shear viscosity of neutron matter from realistic nucleon-nucleon interactions
Benhar, Omar; Valli, Marco
2007-01-01
The calculation of transport properties of Fermi liquids, based on the formalism developed by Abrikosov and Khalatnikov, requires the knowledge of the probability of collisions between quasiparticles in the vicinity of the Fermi surface. We have carried out a numerical study of the shear viscosity of pure neutron matter, whose value plays a pivotal role in determining the stability of rotating neutron stars, in which these processes are described using a state-of-the-art nucleon-nucleon poten...
Nucleon-nucleon scattering in the functional quantum theory of the nonlinear spinor field
International Nuclear Information System (INIS)
The author calculates the S matrix for the elastic nucleon-nucleon scattering in the lowest approximation using the quantum theory of nonlinear spinor fields with special emphasis to the ghost configuration of this theory. Introducing a general scalar product a new functional channel calculus is considered. From the results the R and T matrix elements and the differential and integral cross sections are derived. (HSI)
Nucleon-nucleon potential in the Skyrme model: Beyond the product approximation
International Nuclear Information System (INIS)
Exact numerical calculations with Lagrange constraints are used to determine the lowest terms in an expansion for the two-Skyrmion interaction. The nucleon-nucleon potential which results after semiclassical quantization compares better with the phenomenological Paris potential than do previous calculations in the Skyrme model which used the product approximation. In particular, the present calculations show a sizable medium-range attraction in the central channel, a result that is not found with the product approximation
Microscopic in-medium nucleon-nucleon cross sections with improved Pauli blocking effects
B. Chen; Sammarruca, F.; Bertulani, C. A.
2013-01-01
We present updated predictions of effective elastic nucleon-nucleon cross sections intended for use in nucleus-nucleus reactions. A novel characteristic of the present approach combines all microscopic medium effects included in the Dirac-Brueckner-Hartree-Fock G-matrix with a Pauli blocking mechanism which is more appropriate for applications in ion-ion reaction models as compared to a previous approach. The effective in-medium cross section is found to be quite sensitive to the description ...
Six-quark state widths in the nucleon-nucleon scattering
International Nuclear Information System (INIS)
Using the equations coupling the six-quark and nucleon-nucleon channels the expressions for the width GITA and shift Δ of the six-quark states are obtained. Estimations for s-scattering at 0.3 GeV give a value of an order of GITA=20 MeV. The problem of the existence of dibaryon states is considered from the viewpoint of the coupled channel method
Energy Technology Data Exchange (ETDEWEB)
Yokosawa, A.
1985-01-01
We review experimental results concerning polarization phenomena in nucleon-nucleon scattering in which both the elastic scattering and hadron-production reaction are included. We also present summary of S = 0 dibaryon resonances and candidates by reviewing experimental data in the nucleon-nucleon system, ..gamma..d channel, ..pi..d elastic scattering, pp ..-->.. ..pi..d channel, deuteron break-up reactions, and narrow structures in missing-mass spectra. 93 refs., 26 figs.
Probing short-range nucleon-nucleon interactions with an Electron-Ion Collider
Miller, Gerald A; Venugopalan, Raju
2015-01-01
We derive the cross-section for exclusive vector meson production in high energy deeply inelastic scattering off a deuteron target that disintegrates into a proton and a neutron carrying large relative momentum in the final state. This cross-section can be expressed in terms of a novel gluon Transition Generalized Parton Distribution (T-GPD); the hard scale in the final state makes the T-GPD sensitive to the short distance nucleon-nucleon interaction. We perform a toy model computation of this process in a perturbative framework and discuss the time scales that allow the separation of initial and final state dynamics in the T-GPD. We outline the more general computation based on the factorization suggested by the toy computation: in particular, we discuss the relative role of "point-like" and "geometric" Fock configurations that control the parton dynamics of short range nucleon-nucleon scattering. With the aid of exclusive $J/\\Psi$ production data at HERA, as well as elastic nucleon-nucleon cross-sections, w...
International Nuclear Information System (INIS)
Various aspects of nuclear physics at intermediate energies, in connection with the description of the nucleon-nucleon potential in terms of mesons, are presented in this thesis. The meson exchange current contribution is studied in the case of the deuteron (np capture and electrodisintegration near threshold). A consistent description of these processes is discussed, with particular emphasis on the effective range of the current, for momentum transfers as large as q2∼1 (GeV/c)2. The structure of finite nuclei and nuclear matter is then analysed in the framework of a relativistic formalism, in which the negative energy component of the nucleon wave function is explicitly taken into account. The nuclear matter saturation mechanism is studied in details and compared with the non-relativistic limit. Properties of finite nuclei are also discussed. Finally, the structure of the nucleon itself in the nuclear medium is investigated. A connection between the polarisation of the nucleon (three valence quark component), the incompressibility parameter and the mass of the first monopole excitation of the nucleon is presented
Energy Technology Data Exchange (ETDEWEB)
Hogerton, John
1964-01-01
This pamphlet describes how reactors work; discusses reactor design; describes research, teaching, and materials testing reactors; production reactors; reactors for electric power generation; reactors for supply heat; reactors for propulsion; reactors for space; reactor safety; and reactors of tomorrow. The appendix discusses characteristics of U.S. civilian power reactor concepts and lists some of the U.S. reactor power projects, with location, type, capacity, owner, and startup date.
International Nuclear Information System (INIS)
The Bethe-Salpeter equation is solved in closed form with the help of a four dimensional separable 'potential'. For possible applications to three-nucleon investigations the authors have fitted all nucleon-nucleon S-wave phase shifts in a sufficient way by this method; in addition they also present an example for a P-wave. (Auth.)
Nucleon structure as a background for determination of fundamental parameters
International Nuclear Information System (INIS)
We consider deep inelastic, (quasi-) elastic lepton-nucleon scattering and investigate the possibilities of eliminating or suppressing theoretical uncertainties induced by nucleon structure in measuring the Standard Model parameters or in searching for new physics. On the basis of rather general hypothesis about nucleon structure we have obtained new relations between cross sections and neutral current parameters which are independent of the nucleon structure. We also investigate a dependence of the QCD Λ-parameter extracted from the data on unknown large scale nucleon structure and propose a modification of the conventional QCD predictions which are weakly dependent of this uncertainty factor. (author). 9 refs, 1 tab
Babenko, V A
2016-01-01
We study relationship between the physical quantities that characterize pion-nucleon and nucleon-nucleon interaction on the basis of the fact that nuclear forces in the nucleon-nucleon system at low energies are mainly determined by the one-pion exchange mechanism. By making use of the recommended proton-proton low-energy scattering parameters, we obtain the following value for the charged pion-nucleon coupling constant g$_{\\pi ^{\\pm }}^{2}/4\\pi =14.55(13)$. Calculated value of this quantity is in excellent agreement with the experimental result g$_{\\pi ^{\\pm }}^{2}/4\\pi =14.52(26)$ of the Uppsala Neutron Research Group. At the same time, the obtained value of the charged pion-nucleon coupling constant differs markedly from the value of the neutral pion-nucleon coupling constant g$_{\\pi ^{0}}^{2}/4\\pi =13.55(13)$. Thus, our results show considerable charge splitting of the pion-nucleon coupling constant.
Alvioli, M; Kaptari, L P; Mezzetti, C B; Morita, H; Scopetta, S
2011-01-01
Using realistic wave functions, the proton-neutron and proton-proton momentum distributions in $^3He$ and $^4He$ are calculated as a function of the relative, $k_{rel}$, and center of mass, $K_{CM}$, momenta, and the angle between them. For large values of ${k}_{rel}\\gtrsim 2\\,\\,fm^{-1}$ and small values of ${K}_{CM} \\lesssim 1.0\\,\\,fm^{-1}$, both distributions are angle independent and decrease with increasing $K_{CM}$, with the $pn$ distribution factorizing into the deuteron momentum distribution times a rapidly decreasing function of $K_{CM}$, in agreement with the two-nucleon (2N) short range correlation (SRC) picture. When $K_{CM}$ and $k_{rel}$ are both large, the distributions exhibit a strong angle dependence, which is evidence of three-nucleon (3N) SRC. The predicted center-of-mass and angular dependence of 2N and 3N SRC should be observable in two-nucleon knock-out processes $A(e,e'pN)X$.
Diffraction on nuclei: Effects of nucleon correlations
International Nuclear Information System (INIS)
The cross sections for a variety of diffractive processes in proton-nucleus scattering, associated with large gaps in rapidity, are calculated within an improved Glauber-Gribov theory, where the inelastic shadowing corrections are summed to all orders by employing the dipole representation. The effects of nucleon correlations, leading to a modification of the nuclear thickness function, are also taken into account. Numerical calculations are performed for the energies of the Hadron-Electron Ring Accelerator-B experiment, the Relativistic Heavy Ion Collider and Large Hadron Collider, and for several nuclei. It is found that whereas the Gribov corrections generally make nuclear matter more transparent, nucleon correlations act in the opposite direction and have important effects in various diffractive processes.
New model for nucleon generalized parton distributions
Energy Technology Data Exchange (ETDEWEB)
Radyushkin, Anatoly V. [JLAB, Newport News, VA (United States)
2014-01-01
We describe a new type of models for nucleon generalized parton distributions (GPDs) H and E. They are heavily based on the fact nucleon GPDs require to use two forms of double distribution (DD) representations. The outcome of the new treatment is that the usual DD+D-term construction should be amended by an extra term, {xi} E{sub +}{sup 1} (x,{xi}) which has the DD structure {alpha}/{beta} e({beta},{alpha}, with e({beta},{alpha}) being the DD that generates GPD E(x,{xi}). We found that this function, unlike the D-term, has support in the whole -1 <= x <= 1 region. Furthermore, it does not vanish at the border points |x|={xi}.
Lectures on the soliton theory of nucleons
International Nuclear Information System (INIS)
In these lectures we describe models in which the pion field or, more precisely, the chiral fields, are responsible for the binding of quarks in the nucleon. Such bound states in which the quarks constitute a source for the chiral fields, which, in turn, bind the quarks to each other, are called solitons. The starting point for such theories or models are chiral invariant lagrangians. They are not derived from QCD. The Skyrme lagrangian is simpler in that it involves only chiral fields and no quarks. However it may be understood as an effective lagrangian from which the quark degrees of freedom have been integrated out. It is not yet clear to what extent various models are equivalent. The description of the nucleon in these lectures may be viewed as an extension of the T.D. Lee solitons so as to include the pionic degree of freedom
The Form Factors of the Nucleons
Energy Technology Data Exchange (ETDEWEB)
Perdrisat, Charles F. [William and Mary College, JLAB
2013-11-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double-polarization experiments, in comparison with with pre-vious unpolarized cross section data. Here we will review the experimental data base in view of the new results for the proton and the neutron, obtained at MIT-Bates, JLab and MAMI. The rapid evolution of phenomenological models triggered by these high- precision experiments will be discussed. In particular, the possibility that the proton is non-spherical in its ground state, and that the transverse charge density are model in- dependently defined in the infinite momentum frame. Likewise, flavor decomposition of the nucleon form factors into dressed u and d quark form factors, may give information about the quark-diquark structure of the nucleon. The current proton radius "crisis" will also be discussed.
Nucleon Form Factors - A Jefferson Lab Perspective
Arrington, John; Perdrisat, Charles F
2011-01-01
The charge and magnetization distributions of the proton and neutron are encoded in their elastic electromagnetic form factors, which can be measured in elastic electron--nucleon scattering. By measuring the form factors, we probe the spatial distribution of the proton charge and magnetization, providing the most direct connection to the spatial distribution of quarks inside the proton. For decades, the form factors were probed through measurements of unpolarized elastic electron scattering, but by the 1980s, progress slowed dramatically due to the intrinsic limitations of the unpolarized measurements. Early measurements at several laboratories demonstrated the feasibility and power of measurements using polarization degrees of freedom to probe the spatial structure of the nucleon. A program of polarization measurements at Jefferson Lab led to a renaissance in the field of study, and significant new insight into the structure of matter.
Antinucleon nucleon annihilations into two mesons
International Nuclear Information System (INIS)
We study two aspects of the antinucleon-nucleon annihilation into two mesons (antiNN → M1M2), starting from simple Born diagrams. On one hand, we discuss the possibility of modelling the antiNN optical potential with the box diagrams related to the M1M2 channels. We include the lightest pseudoscalar, scalar and vector mesons with effective coupling constants. Much more channels appear to be needed in order to achieve sensible results. On the other hand, we show that a simple phenomenological optical potential, successfull in reproducing antiNN elastic scattering and total annihilation data can be further used to make predictions on the antiNN → M1M2 processes, which prove to be in good agreement with experiment. We find a lower bound of 17% on the relative contribution of these reactions to the antiNN annihilation. Also, the model favours a rather small effective radius for the nucleon
Physics of the nucleon sea quark distributions
Energy Technology Data Exchange (ETDEWEB)
Vogt, R.
2000-03-10
Sea quark distributions in the nucleon have naively been expected to be generated perturbatively by gluon splitting. In this case, there is no reason for the light quark and anti-quark sea distributions to be different. No asymmetries in the strange or heavy quark sea distributions are predicted in the improved parton model. However,recent experiments have called these naive expectations into question. A violation of the Gottfried sum rule has been measured in several experiments, suggesting that (bar u) < (bar d) in the proton. Additionally, other measurements, while not definitive, show that there may be an asymmetry in the strange and anti-strange quark sea distributions. These effects may require nonperturbative explanations. In this review we first discuss the perturbative aspects of the sea quark distributions. We then describe the experiments that could point to nonperturbative contributions to the nucleon sea. Current phenomenological models that could explain some of these effects are reviewed.
Nucleon Form Factors - A Jefferson Lab Perspective
Energy Technology Data Exchange (ETDEWEB)
John Arrington, Kees de Jager, Charles F. Perdrisat
2011-06-01
The charge and magnetization distributions of the proton and neutron are encoded in their elastic electromagnetic form factors, which can be measured in elastic electron--nucleon scattering. By measuring the form factors, we probe the spatial distribution of the proton charge and magnetization, providing the most direct connection to the spatial distribution of quarks inside the proton. For decades, the form factors were probed through measurements of unpolarized elastic electron scattering, but by the 1980s, progress slowed dramatically due to the intrinsic limitations of the unpolarized measurements. Early measurements at several laboratories demonstrated the feasibility and power of measurements using polarization degrees of freedom to probe the spatial structure of the nucleon. A program of polarization measurements at Jefferson Lab led to a renaissance in the field of study, and significant new insight into the structure of matter.
Spin and angular momentum in the nucleon
Energy Technology Data Exchange (ETDEWEB)
Franz Gross, Gilberto Ramalho, Teresa Pena
2012-05-01
Using the covariant spectator theory (CST), we present the results of a valence quark-diquark model calculation of the nucleon structure function f(x) measured in unpolarized deep inelastic scattering (DIS), and the structure functions g1(x) and g2(x) measured in DIS using polarized beams and targets. Parameters of the wave functions are adjusted to fit all the data. The fit fixes both the shape of the wave functions and the relative strength of each component. Two solutions are found that fit f(x) and g1(x), but only one of these gives a good description of g2(x). This fit requires the nucleon CST wave functions contain a large D-wave component (about 35%) and a small P-wave component (about 0.6%). The significance of these results is discussed.
Transverse nucleon structure and multiparton interactions
Strikman, Mark
2011-01-01
The transverse structure of the nucleon as probed in hard exclusive processes plays critical role in the understanding of the structure of the underlying event in hard collisions at the LHC, and multiparton interactions. We summarize results of our recent studies of manifestation of transverse nucleon structure in the hard collisions at the LHC, new generalized parton distributions involved in multiparton interactions, presence of parton fluctuations. The kinematic range where interaction of fast partons of the projectile with the target reach black disk regime (BDR) strength is estimated. We demonstrate that in the BDR postselection effect leads to effective fractional energy losses. This effect explains regularities of the single and double forward pion production in $ dAu$ collisions at RHIC and impacts on the forward physics in $pp$ collisions at the LHC.
Low-energy pion-nucleon scattering
International Nuclear Information System (INIS)
An analysis of low-energy charged pion-nucleon data from recent π±p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f2=0.0756±0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P31 and P13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided. copyright 1998 The American Physical Society
From Extraction of Nucleon Resonances to LQCD
Lee, T -S H; Kamano, Hiroyuki
2016-01-01
The intrinsic difficulties in extracting the hadron resonances from reaction data are illustrated by using several exactly soluble $\\pi\\pi$ scattering models. The finite-volume Hamiltonian method is applied to predict spectra using two meson-exchange Hamiltonians of $\\pi N$ reactions. Within a three-channel model with $\\pi N$, $\\pi\\Delta$ and $\\sigma N$ channels, we show the advantage of the finite-volume Hamiltonian method over the approach using the L\\"uscher formula to test Lattice QCD calculations aimed at predicting nucleon resonances. We discuss the necessary steps for using the ANL-Osaka eight-channel Hamiltonian to predict the spectra for testing the LQCD calculations for determining the excited nucleon states up to invariant mass $W= 2 $ GeV.
From Extraction of Nucleon Resonances to LQCD
Lee, T.-S. H.; Wu, Jia-jun; Kamano, Hiroyuki
2016-06-01
The intrinsic difficulties in extracting the hadron resonances from reaction data are illustrated by using several exactly soluble π π scattering models. The finite-volume Hamiltonian method is applied to predict spectra using two meson-exchange Hamiltonians of π N reactions. Within a three-channel model with π N , π {Δ} and σ N channels, we show the advantage of the finite-volume Hamiltonian method over the approach using the Lüscher formula to test Lattice QCD calculations aimed at predicting nucleon resonances. We discuss the necessary steps for using the ANL-Osaka eight-channel Hamiltonian to predict the spectra for testing the LQCD calculations for determining the excited nucleon states up to invariant mass W= 2 GeV.
Electron magnetic scattering on valence nucleon orbits
International Nuclear Information System (INIS)
Cross-sections for elastic electron scattering by the magnetization distribution of 49Ti, 51V, 59Co, 87Sr and 93Nb have been measured in the range of momentum transfer 1.7 - 3.3 fm-1. The results are interpreted in terms of radial distribution of the unpaired proton or neutron. Meson exchange and core polarisation effects are investigated. The valence nucleon radii obtained are compared with Hartree-Fock predictions
Nucleon Structure and Generalized Parton Distributions
Energy Technology Data Exchange (ETDEWEB)
Eric Voutier
2006-06-28
This paper discusses a selected part of the experimental program dedicated to the study of Generalized Parton Distributions, a recently introduced concept which provides a comprehensive framework for investigations of the partonic structure of the nucleon. Particular emphasis is put on the Deeply Virtual Compton Scattering program performed at the Jefferson Laboratory. The short and long term future of this program is also discussed in the context of the several experimental efforts aiming at a complete and exhaustive mapping of Generalized Parton Distributions.
Personal history of nucleon polarization experiments
International Nuclear Information System (INIS)
The history of nucleon scattering experiments is reviewed, starting with the observation of large proton polarizations in scattering from light elements such as carbon, and ending with the acceleration of polarized proton beams in high-energy synchrotrons. Special mention is made about significant contributions made by C.L. Oxley, L. Wolfenstein, R.D. Tripp, T. Ypsilantis, A. Abragam, M. Borghini, T. Niinikoski, Froissart, Stora, A.D. Krisch, and L.G. Ratner
Effective Theories for Dark Matter Nucleon Scattering
Hisano, Junji; Nagai, Ryo; Nagata, Natsumi
2015-01-01
We reformulate the calculation of the dark matter-nucleon scattering cross sections based on the method of effective field theories. We assume that the scatterings are induced by the exchange of colored mediators, and construct the effective theories by integrating out the colored particles. All of the leading order matching conditions as well as the renormalization group equations are presented. We consider a Majorana fermion, and real scalar and vector bosons for the dark matter and show th...
Asymmetries of quark sea in nucleon
Dahiya Harleen
2014-01-01
The effects of “quark sea” in determining the flavor structure of the octet baryons have been investigated in the chiral constituent quark model. The chiral constituent quark model is able to qualitatively generate the requisite amount of quark sea and is also known to provide a satisfactory explanation of the proton spin and related issues in the nonperturbative regime. The phenomenological implications of the quark sea asymmetries in the nucleon have been investigated to understand the impo...
Antiquark distributions in pion and nucleon
International Nuclear Information System (INIS)
Relation between the antiquark distributions in pion and nucleon, based on the π-exchange hypothesis, is derived. The antiquark distributions in proton are calculated with the data on the valence antiquark distribution in pion as input. Results of the calculation agree with the experimental data. The role of the peripheral mechanism in formulation of the initial conditions for the chromodynamical evolution equations is discussed
Transfer of nucleons at high relative velocities
Von Oertzen, W.
1985-02-01
We discuss nucleon transfer between bound states of nuclei at high relative velocities. It is shown that the tails of the internal momentum distributions of the nuclear states participating in the transition strongly influence the transfer probabilities at energies between 30-90 MeV/u. Data and DWBA calculations show an exponential decrease of the cross sections in this energy regime and we dub it TGV (Transfer à Grande Vitesse).
Nucleon electromagnetic form factors with Wilson fermions
International Nuclear Information System (INIS)
The nucleon electromagnetic form factors continue to be of major interest for experimentalists and phenomenologists alike. They provide important insights into the structure of nuclear matter. For a range of interesting momenta they can be calculated on the lattice. The limiting factor continues to be the value of the pion mass. We present the latest results of the QCDSF collaboration using gauge configurations with two dynamical, non-perturbatively improved Wilson fermions at pion masses as low as 350 MeV. (orig.)
Nucleon electromagnetic form factors with Wilson fermions
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Haegler, P. [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (GB). School of Physics] (and others)
2007-10-15
The nucleon electromagnetic form factors continue to be of major interest for experimentalists and phenomenologists alike. They provide important insights into the structure of nuclear matter. For a range of interesting momenta they can be calculated on the lattice. The limiting factor continues to be the value of the pion mass. We present the latest results of the QCDSF collaboration using gauge configurations with two dynamical, non-perturbatively improved Wilson fermions at pion masses as low as 350 MeV. (orig.)
Spectral Content of Isoscalar Nucleon Form Factors
Hammer, H. -W.; Ramsey-Musolf, M. J.
1998-01-01
The nucleon strange vector and isoscalar electromagnetic form factors are studied using a spectral decomposition. The K\\bar{K} contribution to the electric and magnetic radii as well as the magnetic moment is evaluated to all orders in the strong interaction using an analytic continuation of experimental KN scattering amplitudes and bounds from unitarity. The relationship between non-resonant and resonant K\\bar{K} contributions to the form factors is demonstrated, and values for the vector an...
Leading logarithms for mesons and nucleons
Bijnens, Johan; Kampf, Karol; Vladimirov, Alexey
2015-01-01
This talk describes the work done in calculating leading logarithms in massive effective field theories. We discuss shortly leading logarithms in renormalizable theories and how they can be calculated using only one-loop calculations in effective field theories. The remainder of the talk discusses masses, decay constants, condensates and anomalous processes in mesonic effective field theories like Chiral Perturbation Theory and the expansion of the nucleon mass.
Few-Nucleon Research at TUNL: Probing Two- and Three-Nucleon Interactions with Neutrons
Howell, C. R.; Tornow, W.; Witała, H.
2016-03-01
The central goal of few-nucleon research at the Triangle Universities Nuclear Laboratory (TUNL) is to perform measurements that contribute to advancing ab-initio calculations of nuclear structure and reactions. The program aims include evaluating theoretical treatments of few-nucleon reaction dynamics through strategically comparing theory predictions to data, determining properties of the neutron-neutron interaction that are not accessible in two-nucleon reactions, and searching for evidence of longrange features of three-nucleon interactions, e.g., spin and isospin dependence. This paper will review studies of three- and four-nucleon systems at TUNL conducted using unpolarized and polarized neutron beams. Measurements of neutron-induced reactions performed by groups at TUNL over the last six years are described in comparison with theory predictions. The results are discussed in the context of the program goals stated above. Measurements of vector analyzing powers for elastic scattering in A=3 and A=4 systems, differential cross sections for neutron-deuteron elastic scattering and neutrondeuteron breakup in several final-state configurations are described. The findings from these studies and plans for the coming three years are presented in the context of worldwide activities in this front, in particular, research presented in this session.
Extra dimensions, SN1987a, and nucleon-nucleon scattering data
Hanhart, C; Reddy, S; Savage, M J; Hanhart, Christoph; Phillips, Daniel R.; Reddy, Sanjay; Savage, Martin J.
2001-01-01
One of the strongest constraints on the existence of large, compact, "gravity-only" dimensions comes from SN1987a. If the rate of energy loss into these putative extra dimensions is too high, then the neutrino pulse from the supernova will differ from that actually seen. The dominant mechanism for the production of Kaluza-Klein gravitons and dilatons in the supernova is via gravistrahlung and dilastrahlung from the nucleon-nucleon system. In this paper we compute the rates for these processes in a model-independent way using low-energy theorems which relate the emissivities to the measured nucleon-nucleon cross section. This is possible because for soft gravitons and dilatons the leading contribution to the energy-loss rate is from graphs in which the gravitational radiation is produced from external nucleon legs. Previous calculations neglected these mechanisms. We re-evaluate the bounds on toroidally-compactified "gravity-only" dimensions (GODs), and find that consistency with the observed SN1987a neutrino ...
Lectures on the soliton theory of nucleons
International Nuclear Information System (INIS)
In the absence of bona fide QCD calculations of nucleon structure (excepting lattice gauge calculations which do not give much detail on the structure of nucleons) new models seem to come up almost every year, all with the claim that QCD will eventually justify them as valid phenomenological models. Other papers show the necessity of implementing simple models (such as the MIT bag model or, more generally, T.D. Lee solitons) with the pionic degree of freedom. In this paper the authors describe models in which it is the pion field or, more precisely, the chiral fields, which are responsible for the binding of quarks in the nucleon. Such bound states in which the quarks constitute a source for the chiral fields, which, in turn, bind the quarks to each other, are called solitons. The starting point for such theories or models are chiral invariant lagrangians, which have been used, in various contexts, for almost a quarter of a century. They are not derived from QCD. It has been argued however that QCD is likely to produce such effective lagrangians for the description of low q phenomena. The Skyrme lagrangian is simpler in that it involves only chiral fields and no quarks. However it may be understood as an effective lagrangian from which the quark degrees of freedom have been integrated out. It is not yet clear to what extent various models are equivalent
One nucleon overlap integrals for light nuclei
International Nuclear Information System (INIS)
A microscopic method to calculate one nucleon overlap integrals for light nuclei is presented. This method is based on the solution of the inhomogeneous differential equation with a fully microscopic treatment of a source term. The source term is calculated with effective two-body nucleon-nucleon (NN) forces and many-body nuclear wave functions represented in a translation-invariant shell model basis. Such an approach automatically provides the correct asymptotic behaviour of the overlap integral. Numerical calculations have been performed for the left angle 7Be*n x p vertical stroke 8Bg.s. right angle, left angle 7Lig.s. x n vertical stroke 8Lig.s. right angle and left angle 10Beg.s. x n vertical stroke 11Be*(1/2 -) right angle overlaps. It has been found that the spectroscopic factors, obtained as norms of the calculated overlap integrals, depend on the choice of the NN-potential and may differ strongly from the corresponding shell model values. The shapes of the overlap integrals are not very sensitive to the NN-potentials used in the calculations, and are mainly determined by the oscillator radius. The microscopically calculated overlaps are close to the two-body potential-model wave functions obtained with standard geometric parameters of the Woods-Saxon potential. (orig.)
Method of unitary clothing transformations in the theory of nucleon-nucleon scattering
Dubovyk, I; 10.1007/s00601-010-097-5
2010-01-01
The clothing procedure, put forward in quantum field theory (QFT) by Greenberg and Schweber, is applied for the description of nucleon-nucleon (N-N) scattering. We consider pseudoscalar, vector and scalar meson fields interacting with fermion ones via the Yukawa-type couplings to introduce trial interactions between "bare" particles. The subsequent unitary clothing transformations (UCTs) are found to express the total Hamiltonian through new interaction operators that refer to particles with physical (observable) properties, the so-called clothed particles. In this work, we are focused upon the Hermitian and energy-independent operators for the clothed nucleons, being built up in the second order in the coupling constants. The corresponding analytic expressions in momentum space are compared with the separate meson contributions to the one-boson-exchange potentials in the meson theory of nuclear forces. In order to evaluate the T-matrix of the N-N scattering we have used an equivalence theorem that enables us...
Non-locality of the nucleon-nucleon potential from Lattice QCD
Murano, Keiko; Aoki, Sinya; Hatsuda, Tetsuo
2010-01-01
The Nambu-Bethe-Salpeter (NBS) wave function for two nucleons on the lattice has been shown to yield a non-local and energy-independent nucleon-nucleon (NN) potential, U(r,r'). In practice, the derivative expansion of U(r,r') is currently employed to determine the potential at low energies. In this report, we study the magnitude of non-locality to check the convergence of such a derivative expansion. With quenched lattice QCD at m_\\pi = 530MeV, we compare the NN potentials at the center of mass energy E ~ 0 MeV and at E ~ 45 MeV. We also investigate the angular momentum dependence of the spin singlet potential, by comparing the potentials in 1S0 and 1D2 channels. We find that the non-locality and the angular momentum dependence in the above energy range are negligible within statistical errors.
Okołowicz, J.; Lam, Y. H.; Płoszajczak, M.; Macchiavelli, A. O.; Smirnova, N. A.
2016-06-01
There is a considerable interest in understanding the dependence of one-nucleon removal cross sections on the asymmetry of the neutron Sn and proton Sp separation energies, following a large amount of experimental data and theoretical analyses in a framework of sudden and eikonal approximations of the reaction dynamics. These theoretical calculations involve both the single-particle cross section and the shell-model description of the projectile initial state and final states of the reaction residues. The configuration mixing in shell-model description of nuclear states depends on the proximity of one-nucleon decay threshold but does it depend sensitively on Sn -Sp? To answer this question, we use the shell model embedded in the continuum to investigate the dependence of one-nucleon spectroscopic factors on the asymmetry of Sn and Sp for mirror nuclei 24Si, 24Ne and 28S, 28Mg and for a series of neon isotopes (20 ≤ A ≤ 28).
Probing short-range nucleon-nucleon interactions with an electron-ion collider
Miller, Gerald A.; Sievert, Matthew D.; Venugopalan, Raju
2016-04-01
We derive the cross section for exclusive vector meson production in high-energy deeply inelastic scattering off a deuteron target that disintegrates into a proton and a neutron carrying large relative momentum in the final state. This cross section can be expressed in terms of a novel gluon transition generalized parton distribution (T-GPD); the hard scale in the final state makes the T-GPD sensitive to the short-distance nucleon-nucleon interaction. We perform a toy model computation of this process in a perturbative framework and discuss the time scales that allow the separation of initial- and final-state dynamics in the T-GPD. We outline the more general computation based on the factorization suggested by the toy computation: In particular, we discuss the relative role of "pointlike" and "geometric" Fock configurations that control the parton dynamics of short-range nucleon-nucleon scattering. With the aid of exclusive J /ψ production data at the Hadron-Electron Ring Accelerator at DESY, as well as elastic nucleon-nucleon cross sections, we estimate rates for exclusive deuteron photodisintegration at a future Electron-Ion Collider (EIC). Our results, obtained using conservative estimates of EIC integrated luminosities, suggest that center-of-mass energies sNN˜12 GeV2 of the neutron-proton subsystem can be accessed. We argue that the high energies of the EIC can address outstanding dynamical questions regarding the short-range quark-gluon structure of nuclear forces by providing clean gluon probes of such "knockout" exclusive reactions in light and heavy nuclei.
Study of the baryon-baryon interaction in nucleon-nucleon and pion-deuteron scattering
International Nuclear Information System (INIS)
After the definition of the Hamiltonian in general form by meson production and absorption the transition to operators pursued, which connect only spaces with definite meson numbers. In this approximation first the self-energy of a single baryon was calculated in its full energy and momentum dependence. Then the formal expressions for the T matrices of nucleon-nucleon and pion-deuteron scattering were derived. The essential components of these expressions are the baryon-baryon T matrix ant transition amplitudes from pion-deuteron channels to baryon-baryon states. The central chapter dealt with the calculation of the baryon-baryon interaction for the general form of the vertices, with the solution of the binding problem and the baryon-baryon T matrix. Finally followed the results on the nucleon-nucleon and pion-deuteron scattering. For this first the transition amplitudes from pion-deuteron states to intermediate baryon-baryon states and the Born graphs of the pion-deuteron scattering had to be calculated. After some remarks to the transition from partial-wave decomposed T matrices to scattering observables an extensive representation of the total, partial, and differential cross sections and a series of spin observables (analyzing powers and spin correlations) for the elastic proton-proton, neutron-proton, and pion-deuteron scattering as well for the fusion reaction pp→πd and the breakup reaction πd→pp follows. Thereby the energies reached from the nucleon-nucleon respectively pion-deuteron threshold up to 100 MeV above the delta resonance
Partial-Wave Analysis of Nucleon-Nucleon Elastic Scattering Data
Workman, Ron L; Strakovsky, Igor I
2016-01-01
Energy-dependent and single-energy fits to the existing nucleon-nucleon database have been updated to incorporate recent measurements. The fits cover a region from threshold to 3 GeV, in the laboratory kinetic energy, for proton-proton scattering, with an upper limit of 1.3 GeV for neutron-proton scattering. Experiments carried out at the COSY-WASA and COSY-ANKE facilities have had a significant impact on the partial-wave solutions. Results are discussed in terms of both partial-wave and direct reconstruction amplitudes.
Search for nucleon-nucleon correlations in neutrino-argon scattering
Niewczas, Kajetan
2015-01-01
A sample of two proton and no pion events selected in the ArgoNeuT neutrino scattering experiment on liquid argon target [Phys. Rev. D90 (2014) 012008] is analyzed with NuWro Monte Carlo event generator. An attempt is made to estimate how likely it is to obtain observed numbers of laboratory frame and reconstructed \\mbox{back-to-back} nucleon pairs. For laboratory frame \\mbox{back-to-back} events a clear data/MC discrepancy is seen. For the reconstructed nucleon pairs a good agreement is reported. We provide a simple kinematical argument why this accordance is expected.
On the nucleon paradigm: the nucleons are closer to reality than the protons and neutrons
Herbut, Fedor
2013-01-01
There is a widespread delusion that in theoretical nuclear physics protons and neutrons are the real thing, and nucleons are not more than a mathematically equivalent formality. It is shown that, on the contrary, nucleons are the real thing, because only a part of the theory is essentially identical to proton-and-neutron theory, whereas the remaining part is physically relevant. The approach is general. Thus, this is a paradigm of relation of a wider and a more narrow theory, so that the wider theory describes reality better. Also the relation of disjoint domains to the exclusion principle is clarified. A general fermion theory of how to distinguish identical particles is presented.
Medium-Heavy Nuclei from Nucleon-Nucleon Interactions in Lattice QCD
Inoue, Takashi; Charron, Bruno; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji
2014-01-01
On the basis of the Brueckner-Hartree-Fock method with the nucleon-nucleon forces obtained from lattice QCD simulations, the properties of the medium-heavy doubly-magic nuclei such as 16^O and 40^Ca are investigated. We found that those nuclei are bound for the pseudo-scalar meson mass M_PS ~ 470 MeV. The mass number dependence of the binding energies, single-particle spectra and density distributions are qualitatively consistent with those expected from empirical data at the physical point, although these hypothetical nuclei at heavy quark mass have smaller binding energies than the real nuclei.
Medium-heavy nuclei from nucleon-nucleon interactions in lattice QCD
Inoue, Takashi; Aoki, Sinya; Charron, Bruno; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji
2014-01-01
On the basis of the Brueckner-Hartree-Fock method with the nucleon-nucleon forces obtained from lattice QCD simulations, the properties of the medium-heavy doubly-magic nuclei such as 16^O and 40^Ca are investigated. We found that those nuclei are bound for the pseudo-scalar meson mass M_PS ~ 470 MeV. The mass number dependence of the binding energies, single-particle spectra and density distributions are qualitatively consistent with those expected from empirical data at the physical point, ...
In-medium nucleon-nucleon cross-sections with non-spherical Pauli blocking
White, L
2014-01-01
We present a formalism to solve the Bethe-Goldstone scattering equation without the use of partial wave expansion which is alternative to the one we developed in a previous work. The present approach is more suitable for the calculation of in-medium nucleon-nucleon cross sections, which are the focal point of this paper. The impact of removing the spherical approximation on the angle and energy dependence of, particularly, in-medium proton-proton and proton-neutron differential cross sections is discussed along with its potential implication.
Low momentum nucleon-nucleon potentials with half-on-shell T-matrix equivalence
Bogner, Scott; Kuo, T. T. S.; Coraggio, L.
2002-01-01
We study a method by which realistic nucleon-nucleon potentials V_NN can be reduced, in a physically equivalent way, to an effective low-momentum potential V-low-k confined within a cut-off momentum k-cut. Our effective potential is obtained using the folded-diagram method of Kuo, Lee and Ratcliff, and it is shown to preserve the half-on-shell T-matrix. Both the Andreozzi-Lee-Suzuki and the Andreozzi-Krenciglowa-Kuo iteration methods have been employed in carrying out the reduction. Calculati...
In-medium nucleon-nucleon cross-sections with non-spherical Pauli blocking
White, L; Sammarruca, F.
2014-01-01
We present a formalism to solve the Bethe-Goldstone scattering equation without the use of partial wave expansion which is alternative to the one we developed in a previous work. The present approach is more suitable for the calculation of in-medium nucleon-nucleon cross sections, which are the focal point of this paper. The impact of removing the spherical approximation on the angle and energy dependence of, particularly, in-medium proton-proton and proton-neutron differential cross sections...
Three-pion exchange nucleon-nucleon potentials with virtual $\\Delta$-isobar excitation
Kaiser, N
2015-01-01
The nucleon-nucleon interaction arising from the exchange of three pions and the excitation of $\\Delta(1232)$-isobars in intermediate states is studied. Approximating the $\\Delta$-propagator by the inverse $\\Delta$N mass-splitting, analytical expressions are derived for the spectral-functions of the isoscalar and isovector central, spin-spin and tensor NN-potentials in momentum-space. A trans- lation of the spectral-functions into coordinate-space potentials reveals that the main effect of these specific exchange and excitation mechanisms is a repulsive isoscalar central NN-potential.
Nucleon flow and fragment flow in heavy ion reactions
International Nuclear Information System (INIS)
The collective flow of nucleons and that of fragments in the 12C+12C reaction below 150 MeV/nucleon are calculated with the antisymmetrized version of molecular dynamics combined with the statistical decay calculation. The density dependent Gogny force is used as the effective interaction. The calculated balance energy is about 100 MeV/nucleon, which is close to the observed value. Below the balance energy, the absolute value of the fragment flow is larger than that of nucleon flow, which is also in accordance with data. The dependence of the flow on the stochastic collision cross section and its origin are discussed. All the results are naturally understood by introducing the concept of two components of flow: the flow of dynamically emitted nucleons and the flow of the nuclear matter which contributes to both the flow of fragments and the flow of nucleons due to the statistical decay
Sensitivity of the deuteron form factor to nucleon resonances
Herbst, K A; Herbst, Kelly Ann; Gross, Franz
1997-01-01
The sensitivity of the deuteron form factor to contributions from the excited states of the nucleon is explored using a simple model of the nucleon-nucleon interaction which employs a tower of charged nucleon resonances. The model is manifestly covariant, analytically solvable, and gauge invariant. The consequences of this model are studied in the simplest possible framework. We assume that all particles have spin zero and that the tower has only three charged members, which consist of the proton, the Roper, and a higher state in the vicinity of the $D_{13}$. Nucleon-nucleon S-wave phase shifts and the deuteron form factor are calculated using this three member tower, and the results are compared to similar calculations using the proton ground state only. We conclude that the deuteron form factor is insensitive to the presence of excited states of the proton unless those states are of sufficiently low mass to produce strong inelasticities in $NN$ scattering channels.
High energy nucleonic component of cosmic rays at mountain altitudes
Stora, Raymond Félix
The diffusion equations describing the unidimensional propagation of .the high energy nucleonic component of cosmic rays throughout the atmosphere are sol"V'ed under two assumptions: (l) The nucleon-nucleon collisions are described according to Fermi's therlnOdynamical model involving completely inelastic pion and.nucleon-antinucleon pair production. (2) A somewhat opposite assumption is made assuming partially elastic collisions without nucleon-anti.nucleon pair production. Due to the present inaccuracy of experiments, we are able to derive only tentati v.e conclusions. The values computed under both hypotheses for the absorption mean free path and the charged to neutral particles ratio are found in acceptable ranges when compared to experimental data. The diffeential energy spectrum at a given depth is always found steeper than the primary, and steeper than indicated by experimental values if the primary is taken proportional to the 2.5 inverse power of energy.
The interaction of a nucleon and alpha condensate
International Nuclear Information System (INIS)
A nucleon is available for examining the property of α-condensate, which consists of composite bosons. Only a microscopic model, which fully takes into account the Pauli principle between all the constituent nucleons, can play its role. We give numerical results by equidistant spectrum model for the system of a neutron and 3α-cluster states. We discuss whether an extra nucleon can exist in the center of α-condensate or not. (author)
Portable nucleonics instrument design: The PortaCAT example
International Nuclear Information System (INIS)
Portable nucleonic gauges prototypes are designed and manufactured in New Zealand for niche applications. Considerable development in hardware and software provide new opportunity in design of relatively low cost portable nucleonic gauges. In this paper are illustrated principles, and specific factors to be consider when designing portable nucleonic instrumentation, using an example called PortaCAT, which is a portable computed tomography scanner designed for imaging wooden power poles. (author)
Orbital and field angular momentum in the nucleon
Singleton, D; Dzhunushaliev, V.
1998-01-01
The nucleon spin problem raises experimental and theoretical questions regarding the contribution of the orbital angular momentum of the quarks to the total spin of the nucleon. In this article we examine the commutation relationships of various operators that contribute to the total angular momentum of the nucleon. We find that the sum of the orbital plus gluon field angular momentum should satisfy the angular momentum commutators, at least up to the one-loop level. This requirement on the s...
Nucleon Structure Functions within a Chiral Soliton Model
Gamberg, L.(Department of Physics, Penn State University-Berks, Reading, PA, 19610, U.S.A.); Reinhardt, H.; Weigel, H.(Physics Department, Stellenbosch University, Matieland 7602, South Africa)
1997-01-01
We study nucleon structure functions within the bosonized Nambu--Jona--Lasinio model where the nucleon emerges as a chiral soliton. We discuss the model predictions on the Gottfried sum rule for electron--nucleon scattering. A comparison with a low--scale parametrization shows that the model reproduces the gross features of the empirical structure functions. We also compute the leading twist contributions of the polarized structure functions $g_{1}(x)$ and $g_{2}(x)$ in this model. We compare...
On the Momentum Dependence of the Nucleon - Nucleus Optical Potential
Kleinmann, M.; Fritz, R.; Müther, H.; Ramos, A.
1994-01-01
The momentum dependence of the mean-field contribution to the real part of the optical model potential is investigated employing realistic nucleon-nucleon interactions. Within a non-relativistic approach a momentum dependence originates from the non-locality of the Fock exchange term. Deducing the real part of the optical model from a relativistic Dirac Brueckner Hartree Fock approximation for the self-energy of the nucleons yields an additional momentum dependence originating from the non-re...
Two Nucleon (B-L)-Conserving Reactions Involving Tau Leptons
Bryman, Douglas
2014-01-01
Tau lepton emission in two-nucleon disappearance reactions from within nuclei which conserve baryon number minus lepton number (B-L) is considered. It is shown that some existing limits on proton decay channels and two-nucleon disappearance reactions resulting in electrons and muons can be applied to $\\Delta B=\\Delta L=2$ decays involving $\\tau$ leptons. For the two-nucleon disappearance channel $np\\to\\tau^+ \\overline\
Majorana Dark Matter Cross Sections with Nucleons at High Energies
Jeong, Yu Seon; Kim, C. S.; Reno, Mary Hall
2012-01-01
Non-relativistic dark matter scattering with nucleons is constrained by direct detection experiments. We use the XENON constraints on the spin-independent and spin-dependent cross section for dark matter scattering with nucleons to constrain a hypothetical Majorana fermionic dark matter particle's couplings to the Higgs boson and Z boson. In the procedure we illustrate the change in the dark matter nucleon cross section as one goes from non-relativistic, coherent scattering to relativistic, i...
Recent results on nucleon sigma terms in lattice QCD
International Nuclear Information System (INIS)
It has proven a significant challenge to experiment and phenomenology to extract a precise values of the nucleon sigma terms. This difficulty opens the window for lattice QCD simulations to lead the field in resolving this aspect of nucleon structure. Here we report on recent advances in the extraction of nucleon sigma terms in lattice QCD. In particular, the strangeness component is now being resolved to a precision that far surpasses best phenomenological estimates.
Development of radioisotope tracer technology and nucleonic control system
Energy Technology Data Exchange (ETDEWEB)
Jin, Joon Ha; Lee, Myun Joo; Jung, Sung Hee and others
1999-04-01
The purpose of this study is to develop the radioisotope tracer technology, which can be used in solving industrial and environmental problems and basic technology of nuclear control systems that are widely used for automation of industrial plants, and to build a strong tracer group to support the local industries. In relation to the tracer technology, the data acquisition system, the column scanning equipment and the detection pig for a leakage test have been developed. In order to use in analyzing data of tracer experiments, a computer program for the analysis of residence time distribution has been created as well. These results were utilized in developing the tracer technologies, such as the column scanning, the flow measurement using the dilution method, the simultaneous monitoring rotational movement of piston rings and the optimization of a waste water treatment facility, and the technologies were successfully demonstrated in the local industrial. The stripper of RFCC reactor has been examined to find an unwanted structure in it by imminent request from the industry. Related to the development of nucleonic control system, the state of art report on the technology has been written and an equipment for the analysis of asphalt content has been developed. (author)
Development of radioisotope tracer technology and nucleonic control system
International Nuclear Information System (INIS)
The purpose of this study is to develop the radioisotope tracer technology, which can be used in solving industrial and environmental problems and basic technology of nuclear control systems that are widely used for automation of industrial plants, and to build a strong tracer group to support the local industries. In relation to the tracer technology, the data acquisition system, the column scanning equipment and the detection pig for a leakage test have been developed. In order to use in analyzing data of tracer experiments, a computer program for the analysis of residence time distribution has been created as well. These results were utilized in developing the tracer technologies, such as the column scanning, the flow measurement using the dilution method, the simultaneous monitoring rotational movement of piston rings and the optimization of a waste water treatment facility, and the technologies were successfully demonstrated in the local industrial. The stripper of RFCC reactor has been examined to find an unwanted structure in it by imminent request from the industry. Related to the development of nucleonic control system, the state of art report on the technology has been written and an equipment for the analysis of asphalt content has been developed. (author)
Use of leptons to study the internal structure of nucleons
International Nuclear Information System (INIS)
In the light of recent results in leptoproduction experiments, a review of the lepton deep inelastic scattering is given. The nucleon structure functions are introduced in the frame of the Quark Parton Model, their Q2 evolution is described with the formalism of Quantum Chromodynamic (QCD) to the leading order. The last experimental results from high energy muon-nucleon and neutrino-nucleon scattering experiments are reported and compared with the QCD predictions. All the experiments are in fair agreement and show a small but clear scaling violation corresponding to the rise with Q2 of the quark-antiquark sea and gluon contributions to the nucleon structure functions
A survey of the alpha-nucleon interaction
International Nuclear Information System (INIS)
A survey of the alpha-nucleon interaction is made. The experimental work on angular distributions of differential scattering cross-sections and polarizations in proton-alpha and neutron-alpha scattering is described. The phenomenological approach which includes the study of both local and non-local potentials reproducing the experimental alpha-nucleon scattering data, is discussed. Basic studies of the alpha-nucleon interaction attempting to build an interaction between an alpha particle and a nucleon from first principles are then described. A critical discussion of the results with some concluding remarks suggesting the direction for further investigation is made. (author)
Electroweak meson production reaction in the nucleon resonance region
International Nuclear Information System (INIS)
We report on our recent study of the the neutrino-nucleon reaction in the nucleon resonance region. The dynamical reaction model of meson production reaction on the nucleon for the pion and photon induced reaction has been developed in order to investigate the spectrum of nucleon excited state. We have extended this model in order to describe the weak meson production reactions with the πN, ηN, KΛ, KΣ and ππN final states. We also studied the role of the final state interaction in the photon and the neutrino induced pion production reaction on the deuteron around the Δ(1232) resonance region
Hard exclusive processes in the one - and two - nucleon systems
International Nuclear Information System (INIS)
A description of hard exclusive processes in the one-and two-nucleon system is attempted in the quark parton approach. The discussion deals with the large momentum transfer electromagnetic form factors of nucleon and deuteron as well as the wide angle, high energy nucleon-nucleon scattering differential cross-section and spin correlation parameters. We review the perturbative Quantum Chromodynamics approach initiated in recent works. The limitations of the approach are emphasized to motivate the consideration of a phenomenological approach. The core parton model introduced some time ago is discussed in both its spinless and spin versions. The predictions are compared with measurements
Nuclear medium effects on pre-equilibrium nucleon emission reactions
International Nuclear Information System (INIS)
Nuclear medium modifies the free nucleon-nucleon interaction cross section. The modified value of the cross section has its own impact on the preequilibrium emission spectrum. Such effect increases or decreases the tendency on neutron emission in comparative with proton emission. Several model of the in-medium nucleon-nucleon interaction cross sections are used in the calculation of the neutron emission spectra for some proton induced reactions. Results showed that as the mass of the target nucleus increases, the nuclear medium produces lesser influence than it does for smaller mass nuclei.
Minimal relativistic model for the three nucleon system
International Nuclear Information System (INIS)
A start is made on disentangling relativistic kinematic effects from ''three body forces'' by presenting a minimal relativistic model in which the internal mesonic degree of freedom is treated on the same footing as the nucleonic degrees of freedom. The meson is not allowed to appear asymptotically, specifying the two-nucleon ''off shell'' amplitudes which can be used to calculate the three nucleon problem. The results are identical to those obtained from the same model starting from three nucleons and one meson. In effect we have discovered a ''relativistic potential model'' which does not generate ''three body forces''. 14 refs
Four-nucleon system with $\\Delta$-isobar excitation
Deltuva, A.; Fonseca, A.C.; Sauer, P. U.
2008-01-01
The four-nucleon bound state and scattering below three-body breakup threshold are described based on the realistic coupled-channel potential CD Bonn + $\\Delta$ which allows the excitation of a single nucleon to a $\\Delta$ isobar. The Coulomb repulsion between protons is included. In the four-nucleon system the two-baryon coupled-channel potential yields effective two-, three- and four-nucleon forces, mediated by the $\\Delta$ isobar and consistent with each other and with the underlying two-n...
Three-nucleon forces in the 1/Nc expansion
Phillips, Daniel R
2013-01-01
The operator structures that can contribute to three-nucleon forces are classified in the 1/Nc expansion. At leading order in 1/Nc a spin-flavor independent term is present, as are the spin-flavor structures associated with the Fujita-Miyazawa three-nucleon force. Modern phenomenological three-nucleon forces are thus consistent with this O(Nc) leading force, corrections to which are suppressed by a power series in 1/Nc^2. A complete basis of operators for the three-nucleon force, including all independent momentum structures, is given explicitly up to next-to-leading order in the 1/Nc expansion.
Directory of Open Access Journals (Sweden)
Shimizu Y.
2010-04-01
Full Text Available Measurements of a complete set of deuteron analyzing powers (iT11, T20, T21, T22 for elastic deuteron–proton scattering at 250 MeV/nucleon have been performed with polarized deuteron beams at RIKEN RI Beam Factory. The obtained data are compared with the Faddeev calculations based on the modern nucleon–nucleon forces together with the Tucson-Melbourne’99, and UrbanaIX three nucleon forces.
Li, Qingfeng; Li, Zhuxia; Soff, Sven; Bleicher, Marcus; Stöcker, Horst
2006-01-01
Several observables of unbound nucleons which are to some extent sensitive to the medium modifications of nucleon-nucleon elastic cross sections in neutron-rich intermediate energy heavy ion collisions are investigated. The splitting effect of neutron and proton effective masses on cross sections is discussed. It is found that the transverse flow as a function of rapidity, the $Q_{zz}$ as a function of momentum, and the ratio of halfwidths of the transverse to that of longitudinal rapidity di...
$\\omega$-Nucleon Interaction and Nucleon Mass in Dense Baryonic Matter
Paeng, Won-Gi; Rho, Mannque; Sasaki, Chihiro
2013-01-01
The dilaton-limit fixed point and the scaling properties of hadrons in the close vicinity of the fixed point in dense baryonic matter uncovered in hidden local symmetry implemented with spontaneously broken scale symmetry are shown to reveal a surprisingly intricate interplay, hitherto unsuspected, between the origin of the bulk of proton mass and the renormalization-group flow of the $\\omega$-nuclear interactions. This rends a theoretical support to the previous (phenomenologically) observed correlation between the dropping nucleon mass and the behavior of the $\\omega$-nuclear interactions in dense matter described in terms of half skyrmions that appear at a density denoted $n_{1/2}$ in skyrmion crystals. The role of the $\\omega$-meson degree of freedom in the source for nucleon mass observed in this paper is highly reminiscent of its important role in the skyrmion description of nucleon mass in hidden local symmetric theory. One of the most notable novel results found in this paper is that the nucleon mass ...
Collective multipole excitations based on correlated realistic nucleon-nucleon interactions
International Nuclear Information System (INIS)
We investigate collective multipole excitations for closed shell nuclei from 16O to 208Pb using correlated realistic nucleon-nucleon interactions in the framework of the random phase approximation (RPA). The dominant short-range central and tensor correlations a re treated explicitly within the Unitary Correlation Operator Method (UCOM), which provides a phase-shift equivalent correlated interaction VUCOM adapted to simple uncorrelated Hilbert spaces. The same unitary transformation that defines the correlated interaction is used to derive correlated transition operators. Using VUCOM we solve the Hartree-Fock problem and employ the single-particle states as starting point for the RPA. By construction, the UCOM-RPA is fully self-consistent, i.e. the same correlated nucleon-nucleon interact ion is used in calculations of the HF ground state and in the residual RPA interaction. Consequently, the spurious state associated with the center-of-mass motion is properly removed and the sum-rules are exhausted within ±3%. The UCOM-RPA scheme results in a collective character of giant monopole, dipole, and quadrupole resonances in closed-shell nuclei across the nuclear chart. For the isoscalar giant monopole resonance, the resonance energies are in agreement with experiment hinting at a reasonable compressibility. However, in the 1- and 2+ channels the resonance energies are overestimated due to missing long-range correlations and three-body contributions. (orig.)
COMMISSIONING OF RHIC AT 100 GEV / NUCLEON.
Energy Technology Data Exchange (ETDEWEB)
TRBOJEVIC,D.; AHRENS,L.; BLASKIEWICZ,M.; BRENNAN,J.M.; BAI,M.; CAMERON,P.; CARDONA,J.; CONNOLLY,R.; DREES,A.; FLILLER,R.P.; ET AL
2002-06-02
This report describes commissioning of the Relativistic Heavy Ion Collider (RHIC) for 100 GeV/nucleon collisions at designed luminosity. To achieve these goals new systems had to be commissioned: Gamma-t transition crossing jump quadrupoles, rebucketing with the new RF storage cavities, phase lock loop feedback, betatron and crystal collimation, beta squeeze along the ramp, Siberian snake magnets for the proton polarization run, AC dipole system chromaticity measurements along the acceleration ramp, orbit correction, new ramp management system, upgraded sequencer, new data instrumentation and logger acquisition system etc.
Electromagnetic studies of nucleon and nuclear structure
International Nuclear Information System (INIS)
Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on 12C and 16O are reported, as well as work on nuclear structure models and instrumentation development
Bedaque, Paulo F.; Griesshammer, Harald W.; Rupak, Gautam
2004-01-01
We use Chiral Perturbation Theory to compute the nucleon mass-shift due to finite volume and temperature effects. Our results are valid up to next-to-leading order in the "\\eps-regime" (mL ~ m\\beta > 1). Based on the two leading orders, we discuss the convergence of the expansion as a function of the lattice size and quark masses. This result can be used to extrapolate lattice results obtained from lattice sizes smaller than the pion cloud, avoiding the numerical simulation of physics under t...
Experimental study of the nucleon spin structure
Energy Technology Data Exchange (ETDEWEB)
Litmaath, M.F.
1996-05-07
After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.).
Nucleon structure functions from constituent quark
Khorramian, Ali N.; Arash, Firooz
1999-10-01
We have used a constituent quarks model to describe the nucleon structure function, F2( χ, Q2), for a wide range of χ=[10 -6,1] and Q2 = [0.5, 5000] GeV2. We have found that although F2 rises as χ decreases, but there exists some χ0 ≤ 10 -4 - 10 -5, below which the rise of F2 subsides drastically and hence, exhibits an almost flat behavior, compatible with the latest results from HERA, at least for low Q2.
Is the nucleon a dirac particle
Energy Technology Data Exchange (ETDEWEB)
Achtzehnter, J.; Wilets, L.
1988-01-01
A two-component Pauli equation for a composite model of the nucleon is derived using a relativistically covariant quark model. Results are presented as an expansion in the momentum and in derivatives for scalar-isoscalar, vector-isoscalar, vector-isovector and electromagnetic external potentials. The Dirac equation fails beginning with the magnetic moment and spin-orbit terms; the failure is modest for isoscalar potentials, but is large for the isovector case. For the vector fields we find anomalous ''magnetic moments'', which are simply related to the corresponding electromagnetic kappa. Preliminary results involving the fields quadratically are also presented. 13 refs.
Wave equation for a composite nucleon
International Nuclear Information System (INIS)
A two-component Pauli equation for a composite model of the nucleon is derived using a relativistically covariant quark model. Scalar-isoscalar, vector-isoscalar, vector-isovector, and electromagnetic external potentials are considered. For the vector fields we find anomalous ''magnetic moments,'' which are simply related to the corresponding electromagnetic κ. The Dirac equation, even if supplemented by anomalous magnetic moments, is found to fail beginning with the Darwin term. However, in Dirac phenomenology, the low-order errors can be compensated by the strengths and functional shapes of the assumed potentials
Wave equation for a composite nucleon
Energy Technology Data Exchange (ETDEWEB)
Achtzehnter, J.; Wilets, L.
1988-07-01
A two-component Pauli equation for a composite model of the nucleon is derived using a relativistically covariant quark model. Scalar-isoscalar, vector-isoscalar, vector-isovector, and electromagnetic external potentials are considered. For the vector fields we find anomalous ''magnetic moments,'' which are simply related to the corresponding electromagnetic kappa. The Dirac equation, even if supplemented by anomalous magnetic moments, is found to fail beginning with the Darwin term. However, in Dirac phenomenology, the low-order errors can be compensated by the strengths and functional shapes of the assumed potentials.
The Quark Spin Distributions of the Nucleon
Ma, Bo-Qiang; Schmidt, Ivan; Soffer, Jacques
1997-01-01
The quark helicity measured in polarized deep inelastic scattering is different from the quark spin in the rest frame of the nucleon. We point out that the quark spin distributions $\\Delta q_{RF}(x)$ are connected with the quark helicity distributions $\\Delta q(x)$ and the quark transversity distributions $\\delta q(x)$ by an approximate relation: $\\Delta q_{RF}(x) + \\Delta q(x)=2 \\delta q(x)$. This relation will be useful in order to measure the rest frame (or quark model) spin distributions ...
Weak η production off the nucleon
International Nuclear Information System (INIS)
The weak η-meson production off the nucleon induced by (anti)neutrinos is studied at low and intermediate energies, the range of interest for several ongoing and future neutrino experiments. We consider Born diagrams and the excitation of N* (1535)S11 and N* (1650)S11 resonances. The vector part of the N-S11 transition form factors has been obtained from the MAID helicity amplitudes while the poorly known axial part is constrained with the help of the partial conservation of the axial current (PCAC) and assuming the pion-pole dominance of the pseudoscalar form factor
KN Scattering and the Nucleon Strangeness Radius
Ramsey-Musolf, M. J.; Hammer, H. -W.
1997-01-01
The leading non-zero electric moment of the nucleon strange-quark vector current is the mean square strangeness radius, $$. We evaluate the lightest OZI-allowed contribution to $$, arising from the kaon cloud, using dispersion relations. Drawing upon unitarity constraints as well as $K^{+}N$ scattering and $e^+e^-\\to K\\bar{K}$ cross section data, we find the structure of this contribution differs significantly from that suggested by a variety of QCD-inspired model calculations. In particular,...
Weak η production off the nucleon
Energy Technology Data Exchange (ETDEWEB)
Alam, M. Rafi; Athar, M. Sajjad [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Alvarez-Ruso, L.; Vacas, M. J. Vicente [Departamento de Física Teórica and Instituto de Física Corpuscular, Centro Mixto Universidad de Valencia-CSIC, E-46071 Valencia (Spain)
2015-05-15
The weak η-meson production off the nucleon induced by (anti)neutrinos is studied at low and intermediate energies, the range of interest for several ongoing and future neutrino experiments. We consider Born diagrams and the excitation of N{sup *} (1535)S{sub 11} and N{sup *} (1650)S{sub 11} resonances. The vector part of the N-S{sub 11} transition form factors has been obtained from the MAID helicity amplitudes while the poorly known axial part is constrained with the help of the partial conservation of the axial current (PCAC) and assuming the pion-pole dominance of the pseudoscalar form factor.
Weak $\\eta$ production off the nucleon
Alam, M Rafi; Athar, M Sajjad; Vacas, M J Vicente
2013-01-01
The weak $\\eta$-meson production off the nucleon induced by (anti)neutrinos is studied at low and intermediate energies, the range of interest for several ongoing and future neutrino experiments. We consider Born diagrams and the excitation of $N^\\ast (1535)S_{11}$ and $N^\\ast(1650)S_{11}$ resonances. The vector part of the N-$S_{11}$ transition form factors has been obtained from the MAID helicity amplitudes while the poorly known axial part is constrained with the help of the partial conservation of the axial current (PCAC) and assuming the pion-pole dominance of the pseudoscalar form factor.
Electroproduction of pions on the nucleon
International Nuclear Information System (INIS)
Electroproduction of pions on the nucleon is investigated with the dynamical model of Nozawa, Blankleider and Lee. The predicted cross sections are in good agreements with the inclusive p(e,e') data, and reproduce to a large extent the p(e,e'π) triple coincidence data. Dependences of the p(e,e'π0) cross sections on the E2 and C2 transition form factors of the γN ↔ Δ excitation are presented. The model-dependence of our predictions is briefly examined by also considering the Gross-Riska approach to parameterize the electromagnetic vertices of the Born(non-resonant) term
Experimental study of the nucleon spin structure
International Nuclear Information System (INIS)
After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.)
Nucleon structure and properties of dense matter
International Nuclear Information System (INIS)
We consider the properties of dense matter in a framework of the Skyrme soliton model and the chiral bag model. The influence of the nucleon structure on the equation of state of dense matter is emphasized. We find that in both models the energy per unit volume is proportional to n4/3, n being the baryon number density. We discuss the properties of neutron stars with a derived equation of state. The role of many-body effects is investigated. The effect of including higher order terms in the chiral lagrangian is examined. The phase transition to quark matter is studied. 29 refs., 6 figs. (author)
Phenomenological study of the nucleon structure functions
International Nuclear Information System (INIS)
This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F2) and polarized (g1) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F2 and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions gp,n,d and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends
The spin structure of the nucleon
International Nuclear Information System (INIS)
The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*ΔΣ + Δg + Lq + Lg where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and Lq and Lg are the orbital momentum of the quark and the gluon respectively. The ΔΣ contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization Δg/g and the so-called transversity. (A.C.)
Three-body antikaon-nucleon systems
Shevchenko, N V
2016-01-01
The paper contains a review of the exact or accurate results achieved in the field of the three-body antikaon-nucleon physics. Different states and processes in $\\bar{K}NN$ and $\\bar{K}\\bar{K}N$ systems are considered. In particular, quasi-bound states in $K^- pp$ and $K^- K^- p$ systems were investigated together with antikaonic deuterium atom. Near-threshold scattering of antikaons on deuteron, including $K^- d$ scattering length, and applications of the scattering amplitudes are also discussed. All exact three-body results were calculated using some form of Faddeev equations. Different versions of $\\bar{K}N$, $\\Sigma N$, $\\bar{K}\\bar{K}$, and $NN$ potentials, specially constructed for the calculations, allowed investigation of the dependence of the three-body results on two-body input. Special attention is paid to the antikaon-nucleon interaction, being the most important for the three-body systems. Additionally performed approximate calculations demonstrate accuracy of the commonly used approaches.
Effective Theories for Dark Matter Nucleon Scattering
Hisano, Junji; Nagata, Natsumi
2015-01-01
We reformulate the calculation of the dark matter-nucleon scattering cross sections based on the method of effective field theories. We assume that the scatterings are induced by the exchange of colored mediators, and construct the effective theories by integrating out the colored particles. All of the leading order matching conditions as well as the renormalization group equations are presented. We consider a Majorana fermion, and real scalar and vector bosons for the dark matter and show the results for each case. The treatment for the twist-2 operators is discussed in detail, and it is shown that the scale of evaluating their nucleon matrix elements does not have to be the hadronic scale. The effects of the QCD corrections are evaluated on the assumption that the masses of the colored mediators are much heavier than the electroweak scale. Our formulation is systematic and model-independent, and thus suitable to be implemented in numerical packages, such as micrOMEGAs and DarkSUSY.
Gauge-invariant decomposition of nucleon spin
Wakamatsu, Masashi
2011-01-01
Based on gauge-invariant decomposition of covariant angular momentum tensor of QCD in an arbitrary Lorentz frame, we investigate the relation between the known decompositions of the nucleon spin into its constituents, thereby clarifying in what respect they are common and in what respect they are different critically. We argue that the decomposition of Bashinsky and Jaffe, that of Chen et al., and that of Jaffe and Manohar are contained in our more general decomposition, after an appropriate gauge-fixing in a suitable Lorentz frame, which means that they all {\\it gauge-equivalent}. We however point out that there is another gauge-invariant decomposition of the nucleon spin, which is closer to the Ji decomposition, while allowing the decomposition of the gluon total angular momentum into its spin and orbital parts. An advantage of the latter decomposition is that each of the four terms corresponds to a definite observable, which can be extracted from high-energy deep-inelastic-scattering measurements.
Nucleon form factors program with SBS at JLAB
Energy Technology Data Exchange (ETDEWEB)
Wojtsekhowski, Bogdan B. [JLAB
2014-12-01
The physics of the nucleon form factors is the basic part of the Jefferson Laboratory program. We review the achievements of the 6-GeV era and the program with the 12- GeV beam with the SBS spectrometer in Hall A, with a focus on the nucleon ground state properties.
Microscopic optical potential from Argonne inter-nucleon potentials
International Nuclear Information System (INIS)
In the present work we describe our results concerning the calculation of equation of state of symmetric zero temperature nuclear matter and the microscopic optical potential using the soft-core Argonne inter-nucleon potentials in first order Brueckner–Hartree–Fock (BHF) theory. The nuclear matter saturates at a density 0.228 nucleon/fm3 with 17.52 MeV binding energy per nucleon for Argonne av-14 and at 0.228 nucleon/fm3 with 17.01 MeV binding energy per nucleon for Argonne av-18. As a test case we present an analysis of 65 and 200 MeV protons scattering from 208Pb. The Argonne av-14 has been used for the first time to calculate nucleon optical potential in BHF and analyze the nucleon scattering data. We also compare our reaction matrix results with those using the old hard-core Hamada–Johnston and the soft-core Urbana uv-14 and Argonne av-18 inter-nucleon potentials. Our results indicate that the microscopic potential obtained using av-14 gives marginally better agreement with the experimental data than the other three Hamiltonians used in the present work. (author)
Examination of the strangeness contribution to the nucleon magnetic moment
Chen, XS; Timmermans, RGE; Sun, WM; Zong, HS; Wang, F
2004-01-01
We examine the nucleon strangeness magnetic moment mu(s) with a lowest order meson cloud model. We observe that (1) strangeness in the nucleon is a natural requirement of the empirical relation mu(p)/mu(n)similar or equal to-3/2, which favors an SU(3) octet meson cloud instead of merely the SU(2) pi
Nucleon Form Factor Experiments and the Pion Cloud
de Jager, Kees
2006-01-01
The experimental and theoretical status of elastic electron scattering from the nucleon is reviewed. A wealth of new data of unprecedented precision, especially at small values of the momentum transfer, in parallel to new theoretical insights, has allowed sensitive tests of the influence of the pionic cloud surrounding the nucleon.
Nucleon self-energy in the relativistic Brueckner theory
Energy Technology Data Exchange (ETDEWEB)
Waindzoch, T.; Fuchs, C.; Faessler, A. [Inst. fuer Theoretische Physik, Univ. Tuebingen (Germany)
1998-06-01
The self-energy of the nucleon in nuclear matter is calculated in the relativistic Brueckner theory. We solve the Thompson equation for the two nucleon scattering in the medium using different Bonn potentials. The self-energy has a rather strong momentum dependence while the equation of state compares well with previous calculations. (orig.)
Two-nucleon transfer reactions uphold supersymmetry in atomic nuclei
Barea, J.; Bijker, R.; Frank, A.
2004-01-01
The spectroscopic strengths of two-nucleon transfer reactions constitute a stringent test for two-nucleon correlations in the nuclear wave functions. A comparison between the recently measured 198Hg(d,alpha)196Au reaction and the predictions from the nuclear quartet supersymmetry lends further support to the validity of supersymmetry in nuclear physics.
Unifying Nucleon and Quark Dynamics at Finite Baryon Number Density
Meyer, J.; Schwenzer, K.; Pirner, H. -J.
1999-01-01
We present a model of baryonic matter which contains free constituent quarks in addition to bound constituent quarks in nucleons. In addition to the common linear sigma-model we include the exchange of vector-mesons. The percentage of free quarks increases with baryon density but the nucleons resist a restoration of chiral symmetry.
Electromagnetic Form Factors of the Nucleon and Compton Scattering
Energy Technology Data Exchange (ETDEWEB)
Charles Hyde-Wright; Cornelis De Jager
2004-12-01
We review the experimental and theoretical status of elastic electron scattering and elastic low-energy photon scattering (with both real and virtual photons) from the nucleon. As a consequence of new experimental facilities and new theoretical insights, these subjects are advancing with unprecedented precision. These reactions provide many important insights into the spatial distributions and correlations of quarks in the nucleon.
Quark cluster model in the three-nucleon system
International Nuclear Information System (INIS)
The quark cluster model is used to investigate the structure of the three-nucleon systems. The nucleon-nucleon interaction is proposed considering the colour-nucleon clusters and incorporating the quark degrees of freedom. The quark-quark potential in the quark compound bag model agrees with the central force potentials. The confinement potential reduces the short-range repulsion. The colour van der Waals force is determined. Then, the probability of quark clusters in the three-nucleon bound state systems are numerically calculated using realistic nuclear wave functions. The results of the present calculations show that quarks cluster themselves in three-quark systems building the quark cluster model for the trinucleon system. (author)
Elastic nucleon-deuteron scattering and breakup with chiral forces
Directory of Open Access Journals (Sweden)
Witała Henryk
2016-01-01
Full Text Available Results on three-nucleon (3N elastic scattering and breakup below the pion production threshold are discussed. The large discrepancies found between a theory based on numerical solutions of 3N Faddeev equations with standard nucleon-nucleon (NN potentials only and data point to the need for three-nucleon forces (3NF’s. This notion is supported by the fact that another possible reason for the discrepancies in elastic nucleon-deuteron (Nd scattering, relativistic effects, turned out to be small. Results for a new generation of chiral NN forces (up to N4LO together with theoretical truncation errors are shown. They support conclusions obtained with standard NN potentials
Resolution issues of nucleon spin in quantum chromodynamics
International Nuclear Information System (INIS)
Lively discussions have been exchanged around the question whether it was possible to completely resolve nucleon spin to the contribution of the intrinsic spin of quarks/gluons and orbital angular momentum, without a contradiction to the color gauge invariance of quantum chromodynamics. This paper firstly showed what performs an essential role in the resolution issues of gauge invariance of nucleon spin, especially in its uniqueness issues, is the invariance toward Lorentz boost in the direction of the momentum of nucleon. What plays a crucial role in the resolution issues of nucleon spin is Lorentz symmetry, and gauge symmetry plays only a minor role. This paper next compared the advantages of two nucleon spin resolutions that are physically non-equivalent, namely, the resolution of canonical. (A.O.)
Nucleon Electric Dipole Moments in High-Scale Supersymmetric Models
Hisano, Junji; Kuramoto, Wataru; Kuwahara, Takumi
2015-01-01
The electric dipole moments (EDMs) of electron and nucleons are the promising probe of the new physics. In the generic high-scale supersymmetric (SUSY) scenarios such as models based on mixture of the anomaly and gauge mediations, gluino has an additional contribution to the nucleon EDMs. In this paper, we estimated the effect of the CP-violating gluon Weinberg operator induced by the gluino chromoelectric dipole moment in the high-scale SUSY scenarios, and we evaluated the nucleon and electron EDMs in these scenarios. We found that in the generic high-scale SUSY models, the nucleon EDMs may receive the sizable contribution from the Weinberg operator. Thus, it is important to compare the nucleon EDMs with the electron EDM in order to discriminate among the high-scale SUSY models.
Nucleon and Elastic and Transition Form Factors
Segovia, Jorge; Cloët, Ian C.; Roberts, Craig D.; Schmidt, Sebastian M.
2014-12-01
We present a unified study of nucleon and elastic and transition form factors, and compare predictions made using a framework built upon a Faddeev equation kernel and interaction vertices that possess QCD-like momentum dependence with results obtained using a symmetry-preserving treatment of a vector vector contact-interaction. The comparison emphasises that experiments are sensitive to the momentum dependence of the running couplings and masses in the strong interaction sector of the Standard Model and highlights that the key to describing hadron properties is a veracious expression of dynamical chiral symmetry breaking in the bound-state problem. Amongst the results we describe, the following are of particular interest: possesses a zero at Q 2 = 9.5 GeV2; any change in the interaction which shifts a zero in the proton ratio to larger Q 2 relocates a zero in to smaller Q 2; there is likely a value of momentum transfer above which ; and the presence of strong diquark correlations within the nucleon is sufficient to understand empirical extractions of the flavour-separated form factors. Regarding the -baryon, we find that, inter alia: the electric monopole form factor exhibits a zero; the electric quadrupole form factor is negative, large in magnitude, and sensitive to the nature and strength of correlations in the Faddeev amplitude; and the magnetic octupole form factor is negative so long as rest-frame P- and D-wave correlations are included. In connection with the transition, the momentum-dependence of the magnetic transition form factor, , matches that of once the momentum transfer is high enough to pierce the meson-cloud; and the electric quadrupole ratio is a keen measure of diquark and orbital angular momentum correlations, the zero in which is obscured by meson-cloud effects on the domain currently accessible to experiment. Importantly, within each framework, identical propagators and vertices are sufficient to describe all properties discussed herein. Our
Energy Technology Data Exchange (ETDEWEB)
Simula, S. [Instituto Nazionale di Fisica Nucleare, Roma (Italy)
1994-04-01
Semi-inclusive deep inelastic lepton scattering off nuclei is investigated assuming that virtual boson absorption occurs on a hadronic cluster which can be either a two-nucleon correlated pair or a six-quark bag. The differences in the energy distribution of nucleons produced in backward and forward directions are analyzed both at x<1 and x>1.
Uzhinsky, V; Hu, Q; Ritman, J; Xu, H
2016-01-01
Parameterization of the nucleon-nucleon elastic scattering amplitude is needed for future experiments with nucleon and nuclear beams in the kinetic energy range 1 - 50 GeV/nucleon. The amplitude is used in Glauber calculations of various cross sections and Monte Carlo simulations of nucleon-nucleon scatterings. Usually, the differential nucleon-nucleon elastic scattering cross sections are described by an exponential expression. Fitting corresponding experimental data on $pp$ interactions at $|t|>$ 0.005 (GeV/c)$^2$ and $|t|\\leq$ 0.125 (GeV/c)$^2$ we have found parameters of the expression and propose formulae for approximations of their energy dependencies in the considered energy range. The same was done for $np$ interactions at $|t|\\leq$ 0.5 (GeV/c)$^2$. Expressions for the energy dependence of the total and elastic cross sections, and the ratio of real to imaginary parts of the amplitude at zero momentum transfer are also given for $pp$ and $np$ collisions. It is sufficient for the Glauber calculations in...
Impact of Nucleon-Nucleon Bremsstrahlung Rates Beyond One-Pion Exchange
Bartl, Alexander; Janka, Hans-Thomas; Schwenk, Achim
2016-01-01
Neutrino-pair production and annihilation through nucleon-nucleon bremsstrahlung is included in current supernova simulations by rates that are based on the one-pion-exchange approximation. Here we explore the consequences of bremsstrahlung rates based on a modern nuclear interactions for proto-neutron star cooling and the corresponding neutrino emission. We find that despite a reduction of the bremsstrahlung emission by a factor of 2-5 in the neutrinospheric region, models with the improved treatment exhibit only $\\lesssim$5% changes of the neutrino luminosities and an increase of $\\lesssim$0.7 MeV of the average energies of the radiated neutrino spectra, with the largest effects for the antineutrinos of all flavors and at late times. Overall, the proto-neutron star cooling evolution is slowed down modestly by $\\lesssim$0.5-1 s.
New large-Nc relations among the nucleon and nucleon-to-Delta GPDs
Energy Technology Data Exchange (ETDEWEB)
Marc Vanderhaeghen; Vladimir Pascalutsa
2006-11-15
We establish relations which express the generalized parton distributions (GPDs) describing the N {yields} {Delta} transition in terms of the nucleon GPDs. These relations are based on the known large-N{sub c} relation between the N {yields} {Delta} electric quadrupole moment and the neutron charge radius, and a newly derived large-N{sub c} relation between the electric quadrupole (E2) and Coulomb quadrupole (C2) transitions. Namely, in the large-N{sub c} limit we find C2=E2. The resulting relations among the nucleon and N {yields} {Delta} GPDs provide predictions for the N {yields} {Delta} electromagnetic form factors which are found to be in very good agreement with experiment for moderate momentum transfers.
Advances in Nucleon-Nucleon Scattering Experiments and Their Theoretical Consequences
International Nuclear Information System (INIS)
An overview of critical analysis of the experimental data obtained from nucleon-nucleon scattering is given and investigated in this work. Comparison of the experimental data with results of recent partial wave analysis of Nijmegen group, VPI/GWU and Saclay is given. Potentials of Nijmegen, Bonn and Argonne group are discussed. Experimental data which lead to the break of charge symmetry, to the break of the charge independence and to the determination of the off-shell tensor force, are particularly emphasized. Disagreements which exist between theoretical calculations related to the contribution of particular mechanism in different reactions are pointed out. In this relation, still open problems to be solved and measurement that should be undertaken in the future are identified, as well
Triton-proton elastic scattering and spin-dependent nucleon-nucleon forces
International Nuclear Information System (INIS)
Angular distributions of the differential cross section and analyzing power Asub(t) have been measured for 1H(t(pol), t)1H scattering at center-of-mass energies Esub(c.m.) = 1.26, 1.68, 2.19, 2.70, 3.21 and 3.71 MeV. At the highest energies, large differences are observed between Asub(t) and the analyzing powers Asub(p) for 3H(p(pol),p)3H scattering. It is shown that the experimental results can yield detailed information on the odd-l spin-orbit and odd-l tensor nucleon-nucleon forces. (Auth.)
Compound-nuclear tests of time reversal invariance in the nucleon-nucleon interaction
International Nuclear Information System (INIS)
The theory for the effects of time-reversal noninvariance (TRNI) in complex systems is reviewed. Applied to the compound-nuclear data for energy-level, width and cross-section fluctuations (the latter for detailed-balance pairs of reactions proceeding through the compound nucleus) this gives bounds on multiparticle TRNI Hamiltonian matrix elements. Using a fluctuation-free form of statistical spectroscopy the results are reduced to bounds on α, the relative magnitude of the TRNI nucleon-nucleon interaction. The level and width analyses for heavy nuclei gave α ≤ 2 x 10-3 at high (∼99%) statistical confidence; preliminary calculations for detailed balance with 24Mg(α,p)27Al and its inverse gives α ≤ 4 x 10-3 at the same high confidence, but ≤0.2 x 10-3 at 80% confidence. Suggestions are made about experiments which should yield sharper bounds. 28 refs., 1 tab
Di-nucleon structures in homogeneous nuclear matter based on two- and three-nucleon interactions
Arellano, H F; Rios, Arnau
2016-01-01
We investigate homogeneous nuclear matter within the Brueckner-Hartree-Fock (BHF) approach in the limits of isospin-symmetric nuclear matter (SNM) as well as pure neutron matter at zero temperature. The study is based on realistic representations of the internucleon interaction as given by Argonne v18, Paris, Nijmegen I and II potentials, in addition to chiral N$^{3}$LO interactions, including three-nucleon forces up to N$^{2}$LO. Particular attention is paid to the presence of di-nucleon bound states structures in $^1\\textrm{S}_0$ and $^3\\textrm{SD}_1$ channels, whose explicit account becomes crucial for the stability of self-consistent solutions at low densities. A characterization of these solutions and associated bound states is discussed. We confirm that coexisting BHF single-particle solutions in SNM, at Fermi momenta in the range $0.13-0.3$~fm$^{-1}$, is a robust feature under the choice of realistic internucleon potentials.
Nucleon-nucleon potential calculated for the cloudy bag and related to effective OBE parameters
International Nuclear Information System (INIS)
The nucleon nucleon potential is calculated in the context of the cloudy bag model. The one pion exchange diagram is used to determine the pion quark coupling. Two pion exchange diagrams, box and crossed box, including the delta isobar, produce additional central, spin-spin, and tensor couplings. Using non-relativistic approximations to the OBE model potentials, the two pion exchange contributions are related to the masses and couplings of σ, ω, δ, and ρ mesons. It is found that the two pion exchange generates essentially all of the σ contribution required by the OBE model, that there is a large δ contribution at a lower mass than expected, and that the ω and ρ contributions, while significant, are not able to provide what is required by the OBE model. copyright 1995 American Institute of Physics
$A_{LT}$ in the Nucleon-Nucleon Polarized Drell-Yan Process
Kanazawa, Y; Nishiyama, N; Koike, Yuji
2000-01-01
We present a leading order (LO) estimate for the longitidinal-transverse spin asymmetry (A_{LT}) in the nucleon-nucleon polarized Drell-Yan process at RHIC and HERA-$\\vec{N}$ energies in comparison with A_{LL} and A_{TT}. A_{LT} receives contribution from g_1, the transversity ditribution h_1, and the twist-3 distributions g_T and h_L. For the twist-3 contribution we use the bag model prediction evolved to a high energy scale by the large-N_c evolution equation. We found that A_{LT} (normalized by the asymmetry in the parton level) is much smaller than the corresponding A_{TT}. Twist-3 contribution given by the bag model also turned out to be negligible.
Dilepton production in nucleon–nucleon collisions around 1 GeV/nucleon: A theoretical update
Indian Academy of Sciences (India)
R Shyam; U Mosel
2010-08-01
We present a fully relativistic and gauge invariant framework for calculating the cross-sections of dilepton production in nucleon–nucleon ( ) collisions which is based on the meson-exchange approximation for the scattering amplitudes. Predictions of our model are compared with those of other covariant models that have been used to describe this reaction. We discuss the comparison of our calculations with the old DLS and the recent HADES data.
Three-nucleon mechanisms in photoreactions
Energy Technology Data Exchange (ETDEWEB)
Watts, D.P.; Ahrens, J.; Annand, J.R.M.; Beck, R.; Branford, D.; Grabmayr, P.; Hehl, T.; Kellie, J.D.; MacGregor, I.J.D.; McGeorge, J.C.; Owens, R.O
2003-01-30
The {sup 12}C({gamma},ppn) reaction has been measured for E{sub {gamma}}=150-800 MeV in the first study of this reaction in a target heavier than {sup 3}He. The experimental data are compared to a microscopic many body calculation. The model, which predicts that the largest contribution to the reaction arises from final state interactions following an initial pion production process, overestimates the measured cross sections and there are strong indications that the overestimate arises in this two-step process. The selection of suitable kinematic conditions strongly suppresses this two-step contribution leaving cross sections in which up to half the yield is predicted to arise from the absorption of the photon on three interacting nucleons and which agree with the model. The results indicate ({gamma},3N) measurements on nuclei may be a valuable tool for obtaining information on the nuclear three-body interaction.
Three-nucleon mechanisms in photoreactions
Watts, D P; Annand, J R M; Beck, R; Branford, D; Grabmayr, P; Hehl, T; Kellie, J D; MacGregor, I J D; McGeorge, J C; Owens, R O
2003-01-01
The $^{12}$C$(\\gamma,ppn)$ reaction has been measured for E$_{\\gamma}$=150-800 MeV in the first study of this reaction in a target heavier than $^3$He. The experimental data are compared to a microscopic many body calculation. The model, which predicts that the largest contribution to the reaction arises from final state interactions following an initial pion production process, overestimates the measured cross sections and there are strong indications that the overestimate arises in this two-step process. The selection of suitable kinematic conditions strongly suppresses this two-step contribution leaving cross sections in which up to half the yield is predicted to arise from the absorption of the photon on three interacting nucleons and which agree with the model. The results indicate $(\\gamma,3N)$ measurements on nuclei may be a valuable tool for obtaining information on the nuclear three-body interaction.
From Nucleons To Nuclei To Fusion Reactions
Energy Technology Data Exchange (ETDEWEB)
Quaglioni, S; Navratil, P; Roth, R; Horiuchi, W
2012-02-15
Nuclei are prototypes of many-body open quantum systems. Complex aggregates of protons and neutrons that interact through forces arising from quantum chromo-dynamics, nuclei exhibit both bound and unbound states, which can be strongly coupled. In this respect, one of the major challenges for computational nuclear physics, is to provide a unified description of structural and reaction properties of nuclei that is based on the fundamental underlying physics: the constituent nucleons and the realistic interactions among them. This requires a combination of innovative theoretical approaches and high-performance computing. In this contribution, we present one of such promising techniques, the ab initio no-core shell model/resonating-group method, and discuss applications to light nuclei scattering and fusion reactions that power stars and Earth-base fusion facilities.
Nucleon form factors. Probing the chiral limit
International Nuclear Information System (INIS)
The electromagnetic form factors provide important hints for the internal structure of the nucleon and continue to be of major interest for experimentalists. For an intermediate range of momentum transfers the form factors can be calculated on the lattice. However, reliability of the results is limited by systematic errors due to the required extrapolation to physical quark masses. Chiral effective field theories predict a rather strong quark mass dependence in a range which was yet unaccessible for lattice simulations. We give an update on recent results from the QCDSF collaboration using gauge configurations with Nf=2, non-perturbatively O(a)-improved Wilson fermions at very small quark masses down to 340 MeV pion mass, where we start to probe the relevant quark mass region. (orig.)
Inelastic electron scattering from a moving nucleon
International Nuclear Information System (INIS)
The authors propose to measure inelastically scattered electrons in coincidence with spectator protons emitted backwards relative to the virtual photon direction in the reaction d(e, e'ps)X. In a simple spectator model, the backward proton has equal and opposite momentum to the neutron before it is struck, allowing the authors to study the dependence on kinematics and off-shell behaviour of the electron-nucleon inelastic cross section. If the photon couples to a quark in a 6-quark bag, a different dependence of the cross section on the kinematic variables (x, Q2, and ps) can be observed. This proposed experiment requires large acceptance and beam energies above 6 GeV. It is ideally suited for the CEBAF Large Acceptance Spectrometer (CLAS)
Where Does the Nucleon Spin Come From?
Ji, Xiangdong
1998-04-01
There has been some interesting theoretical progress recently in studying the spin structure of the nucleon. In QCD, the sources of angular momentum include quark and gluon spin and orbital motion. These contributions can be defined in a gauge invariant way and can be measured in high-energy experiments. Besides the well-known polarized deep-inelastic scattering in which the quark spin contribution has been measured, there is now a proposal to measure the quark orbital angular momentum through deeply virtual Compton scattering. The result of a high-energy measurement depends on the resolution scale of the probe. Such scale dependence for orbital angular momentum has also been understood from perturbative QCD.
Photodisintegration of three- and four- nucleon systems
Sandhas, W; Ellerkmann, G; Howell, L L; Sofianos, S A
1997-01-01
Three- and four-nucleon photodisintegration processes are quite efficiently treated by means of effective two-body integral equations in momentum space. We recall some aspects of their derivation, present previous and most recent results obtained within this framework, and discuss general features, trends and effects observed in these investigations: At low energies final-state interaction plays an important role. Even more pronounced is the effect of meson exchange currents. A considerable potential dependence shows up in the low-energy peak region. The different peak heights are found to be closely correlated with the corresponding binding energies. Above the peak region only the difference between potentials with or without p-wave contributions remains relevant. In the differential cross sections the electric quadrupole contributions have to be taken into account. The remarkable agreement between theory and experiment in $p$-$d$ radiative capture is achieved only when incorporating this contribution, toget...
Inelastic electron scattering from a moving nucleon
Energy Technology Data Exchange (ETDEWEB)
Kuhn, S.E. [Old Dominion Univ., Norfolk, VA (United States); Griffioen, K. [College of William and Mary, Williamsburg, VA (United States)
1994-04-01
The authors propose to measure inelastically scattered electrons in coincidence with spectator protons emitted backwards relative to the virtual photon direction in the reaction d(e, e{prime}p{sub s})X. In a simple spectator model, the backward proton has equal and opposite momentum to the neutron before it is struck, allowing the authors to study the dependence on kinematics and off-shell behaviour of the electron-nucleon inelastic cross section. If the photon couples to a quark in a 6-quark bag, a different dependence of the cross section on the kinematic variables (x, Q{sup 2}, and p{sub s}) can be observed. This proposed experiment requires large acceptance and beam energies above 6 GeV. It is ideally suited for the CEBAF Large Acceptance Spectrometer (CLAS).
Systematic nonlocal optical model potential for nucleons
International Nuclear Information System (INIS)
Based on the Perey–Buck nonlocal optical model potential, F. Perey and B. Buck, Nucl. Phys. 32 (1962) 353, we obtain a new set of nonlocal optical model potential (NLOMP) parameters for proton and neutron scattering off nuclei. The experimental angular distributions of nucleon scattering off nuclei ranging from 27Al to 208Pb with incident energies around 10 MeV to 30 MeV are adopted in the fitting procedures. This NLOMP is energy independent. The chi-squares χ2 obtained in the fittings are comparable to those from the KD03 phenomenological local optical model potentials (OMP) A. Koning and J. Delaroche, Nucl. Phys. A 713 (2003) 231. Good agreement is found in comparisons between optical model calculations using this NLOMP and KD03 in their reproduction to the experimental angular distributions of elastic scattering cross-sections and analyzing powers. (author)
Antineutrino induced antikaon production off the nucleon
Alam, M Rafi; Athar, M Sajjad; Vacas, M J Vicente
2011-01-01
The charged current antikaon production off nucleons induced by antineutrinos is studied at low and intermediate energies. We extend here our previous calculation on kaon production induced by neutrinos. We have developed a microscopic model that starts from the SU(3) chiral Lagrangians and includes background terms and the resonant mechanisms associated to the lowest lying resonance in the channel, namely, the Sigma*(1385). Our results could be of interest for the background estimation of various neutrino oscillation experiments like MiniBooNE and SuperK. They can also be helpful for the planned antineutrino experiments like MINERvA, NOvA and T2K phase II and for beta-beam experiments with antineutrino energies around 1 GeV.
Weak Kaon Production off the Nucleon
Alam, M Rafi; Athar, M Sajjad; Vacas, M J Vicente
2010-01-01
The weak kaon production off the nucleon induced by neutrinos is studied at the low and intermediate energies of interest for some ongoing and future neutrino oscillation experiments. This process is also potentially important for the analysis of proton decay experiments. We develop a microscopical model based on the SU(3) chiral Lagrangians. The basic parameters of the model are fpi, the pion decay constant, Cabibbo's angle, the proton and neutron magnetic moments and the axial vector coupling constants for the baryons octet, D and F, that are obtained from the analysis of the semileptonic decays of neutron and hyperons. The studied mechanisms are the main source of kaon production for neutrino energies up to 1.2 to 1.5 GeV for the various channels and the cross sections are large enough to be amenable to be measured by experiments such as Minerva and T2K.
Peripheral scattering of nucleons by isoscalar targets
International Nuclear Information System (INIS)
As is well known, the exchange of a single pion does not contribute to scattering of nucleons by isoscalar targets, since the pion is an isovector. This simple idea were employed in a recent work in order to probe the next layer of NN interaction and we showed that a clear dependence of phase shifts on the NN potential is obtained. As Nα scattering data is still not free of ambiguity, few conclusions can be extracted. Motivated by more precise Nd scattering data recently available, we began a new study of Nd system. This give us more information about the intermediate region of NN potential, but first we need to study the techniques involved in extracting phase shifts and mixing parameters. (author)
Leading logarithms for the nucleon mass
Directory of Open Access Journals (Sweden)
Johan Bijnens
2015-02-01
Full Text Available Within the heavy baryon chiral perturbation theory approach, we have studied the leading logarithm behavior of the nucleon mass up to four-loop order exactly and we present some results up to six-loop order as well as an all-order conjecture. The same methods allow to calculate the main logarithm multiplying the terms with fractional powers of the quark mass. We calculate thus the coefficients of m2n+1log(n−1(μ2/m2 and m2n+2logn(μ2/m2, with m the lowest-order pion mass. A side result is the leading divergence for a general heavy baryon loop integral.
Structure and spin of the nucleon
Directory of Open Access Journals (Sweden)
Avakian H.
2014-03-01
Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL. TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC, FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Nucleon form factors. Probing the chiral limit
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Haegler, P. [Technische Univ. Muenchen, Garching (Germany). Physik-Dept.; Horsley, R. [Edinburgh Univ. (GB). School of Physics] (and others)
2006-10-15
The electromagnetic form factors provide important hints for the internal structure of the nucleon and continue to be of major interest for experimentalists. For an intermediate range of momentum transfers the form factors can be calculated on the lattice. However, reliability of the results is limited by systematic errors due to the required extrapolation to physical quark masses. Chiral effective field theories predict a rather strong quark mass dependence in a range which was yet unaccessible for lattice simulations. We give an update on recent results from the QCDSF collaboration using gauge configurations with Nf=2, non-perturbatively O(a)-improved Wilson fermions at very small quark masses down to 340 MeV pion mass, where we start to probe the relevant quark mass region. (orig.)
Superscaling and nucleon momentum distributions in nuclei
International Nuclear Information System (INIS)
The scaling functions f(ψ') and F(y) from the ψ'- and y-scaling analyses of inclusive electron scattering from nuclei are constructed within the Coherent Density Fluctuation Model (CDFM) using its two equivalent formulations based on either the local density or the nucleon momentum distribution (NMD). The approach is a natural extension of the relativistic Fermi-gas model to finite realistic nuclear systems. The calculations show that the high-momentum components of NMD in the CDFM and their similarity for different nuclei lead to quantitative description of the super-scaling phenomenon and to a good agreement with the experimental data for y'''- and y-scaling are informative for NMDs at momenta not larger than 2.0-2.5 fm-1. The work shows the role of both basic quantities, the momentum and density distributions, for the explanation of super-scaling in inclusive electron scattering from nuclei
The spin structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Le Goff, J.M
2005-02-15
The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*{delta}{sigma} + {delta}g + L{sub q} + L{sub g} where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and L{sub q} and L{sub g} are the orbital momentum of the quark and the gluon respectively. The {delta}{sigma} contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization {delta}g/g and the so-called transversity. (A.C.)
The method of unitary clothing transformations in the theory of nucleon-nucleon scattering
Dubovyk, I
2010-01-01
The clothing procedure, put forward in quantum field theory by Greenberg and Schweber, is applied for the description of nucleon-nucleon (N-N) scattering. We consider pseudoscalar, vector and scalar meson fields interacting with 1/2 spin fermion ones via the Yukawa-type couplings to introduce trial interactions between "bare" particles. The subsequent unitary clothing transformations are found to express the total Hamiltonian through new interaction operators that refer to particles with physical (observable) properties, the so-called clothed particles. In this work, we are focused upon the Hermitian and energy-independent operators for the clothed nucleons, being built up in the second order in the coupling constants. The corresponding analytic expressions in momentum space are compared with the separate meson contributions to the one-boson-exchange potentials in the meson theory of nuclear forces. In order to evaluate the T-matrix of the N-N scattering we have used an equivalence theorem that enables us to ...
Calculation of the nucleon-nucleon interaction due to vector-meson exchange
International Nuclear Information System (INIS)
We make use of a momentum-space bosonization of a generalized Nambu endash Jona-Lasinio model to calculate the contribution of rho and omega exchange to the one-boson-exchange (OBE) model of the nucleon-nucleon interaction. Momentum-dependent meson-quark coupling constants are obtained in the bosonization scheme. A vector-meson-dominance (VMD) model is used to obtain information concerning the momentum dependence of the meson-nucleon vertex, other than that which arises from the momentum dependence of the meson-quark coupling constants. We find good agreement with the magnitude of the force at q2=0 for both rho and omega exchange. The momentum dependence of the interaction in the region -0.2 GeV2≤q2≤0 was calculated. We only obtain about two-thirds of the strength of the OBE interaction at q2=-0.2 GeV2, suggesting the importance of interactions of shorter range than that considered here. (We note that, for -0.2 GeV2≤q2≤0, we span the range of q2 of significance for nuclear structure studies.) copyright 1996 The American Physical Society
Proceedings of the workshop on two-nucleon system
International Nuclear Information System (INIS)
The workshop on two nucleon system started its works four years ago to promote the experiment project on nucleon-nucleon system in the National Laboratory for High Energy Physics by the close cooperation of experimenters and theorists. In particular, several proposals have been made about the experiments using the polarized targets of hydrogen and deuterium, the spectrometers of large solid angle and others, and the investigation into them have been forwarded. It was decided to publish the results of the fourth meeting held in the National Laboratory for High Energy Physics on October 19 and 20, 1979, as the interim report, summarizing the contents. Some of the initial objectives have not been realized yet, but the data have been produced gradually from the experiments in the National Laboratory for High Energy Physics, and are contributing to various analyses. This report is composed of the physics of nucleon-nucleon systems and anti-nucleon-nucleon systems, the results of experiments and the projects corresponding to them, and the hypothetic round-table talk on the points which this workshop considers as problematic and the views of outside researchers on the National Laboratory for High Energy Physics. Finally, the materials distributed at the time of the meeting are added for reference as the appendix. Some numerical values are mutually different, but adjustment was not made. (Kako, I.)
Nucleon-pair approximation to the nuclear shell model
Energy Technology Data Exchange (ETDEWEB)
Zhao, Y.M., E-mail: ymzhao@sjtu.edu.cn [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Arima, A. [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Musashi Gakuen, 1-26-1 Toyotamakami Nerima-ku, Tokyo 176-8533 (Japan)
2014-12-01
Atomic nuclei are complex systems of nucleons–protons and neutrons. Nucleons interact with each other via an attractive and short-range force. This feature of the interaction leads to a pattern of dominantly monopole and quadrupole correlations between like particles (i.e., proton–proton and neutron–neutron correlations) in low-lying states of atomic nuclei. As a consequence, among dozens or even hundreds of possible types of nucleon pairs, very few nucleon pairs such as proton and neutron pairs with spin zero, two (in some cases spin four), and occasionally isoscalar spin-aligned proton–neutron pairs, play important roles in low-energy nuclear structure. The nucleon-pair approximation therefore provides us with an efficient truncation scheme of the full shell model configurations which are otherwise too large to handle for medium and heavy nuclei in foreseeable future. Furthermore, the nucleon-pair approximation leads to simple pictures in physics, as the dimension of nucleon-pair subspace is always small. The present paper aims at a sound review of its history, formulation, validity, applications, as well as its link to previous approaches, with the focus on the new developments in the last two decades. The applicability of the nucleon-pair approximation and numerical calculations of low-lying states for realistic atomic nuclei are demonstrated with examples. Applications of pair approximations to other problems are also discussed.
General aspects of the nucleon-nucleon interaction and nuclear matter properties
Energy Technology Data Exchange (ETDEWEB)
Plohl, Oliver
2008-07-25
The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are
General aspects of the nucleon-nucleon interaction and nuclear matter properties
International Nuclear Information System (INIS)
The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are
Isospin dependence of nucleon correlations in ground-state nuclei
Energy Technology Data Exchange (ETDEWEB)
Charity, R.J. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Dickhoff, W.H. [Washington University, Department of Physics, St. Louis, Missouri (United States); Sobotka, L.G. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Washington University, Department of Physics, St. Louis, Missouri (United States); Waldecker, S.J. [University of Tennessee, Department of Physics, Chattanooga, Tennessee (United States)
2014-02-15
The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. Such predictions can be investigated by performing experiments with exotic beams. The predicted neutron properties for the double closed-shell {sup 132}Sn nucleus exhibit similar correlations as those in {sup 208}Pb. Future relevance of these studies for understanding the properties of all nucleons, including those with high momentum, and the role of three-body forces in nuclei are briefly discussed. Such an implementation will require a proper treatment of the non-locality of the imaginary part of the potentials and a description of high-momentum nucleons as experimentally constrained by the (e, e' p) reactions performed at Jefferson Lab. (orig.)
Phenomenology of dark matter-nucleon effective interactions
Catena, Riccardo
2015-01-01
I compare the non-relativistic effective theory of one-body dark matter-nucleon interactions to current dark matter direct detection experiments and neutrino telescope observations, presenting exclusion limits on the coupling constants of the theory. In the analysis of direct detection experiments, I focus on the interference of different dark matter-nucleon interaction operators and on predictions observable at directional detectors. Interpreting neutrino telescope observations, I use new nuclear response functions recently derived through nuclear structure calculations and show that hydrogen is not the most important element in the exclusion limit calculation for the majority of the spin-dependent dark matter-nucleon interaction operators
Elastic and inelastic pion reactions on few nucleon systems
Energy Technology Data Exchange (ETDEWEB)
Lensky, V.
2007-09-29
In the present work, we are studying elastic and inelastic pion reactions on few-body systems within the framework of chiral effective theory. We consider two specific reactions involving pions on few-nucleon systems, namely pion production in nucleon-nucleon collisions, and incoherent pion photoproduction on the deuteron. These two reactions are closely related to the issue of dispersive and absorptive corrections to the pion-deuteron scattering length, which we also consider in our analysis. The incoherent pion photoproduction is also considered as the possible source for a high-precision determination of the neutron-neutron scattering length. (orig.)
Spin and Orbital Angular Momentum Distribution Functions of the Nucleon
Wakamatsu, M.; Watabe, T
1999-01-01
A theoretical prediction is given for the spin and orbital angular momentum distribution functions of the nucleon within the framework of an effective quark model of QCD, i.e. the chiral quark soliton model. An outstanding feature of the model is that it predicts fairly small quark spin fraction of the nucleon $\\Delta \\Sigma \\simeq 0.35$, which in turn dictates that the remaining 65% of the nucleon spin is carried by the orbital angular momentum of quarks and antiquarks at the model energy sc...
Nucleon Structure Functions within a Chiral Soliton Model
Gamberg, L P; Weigel, H
1997-01-01
We study nucleon structure functions within the bosonized Nambu--Jona--Lasinio model where the nucleon emerges as a chiral soliton. We discuss the model predictions on the Gottfried sum rule for electron--nucleon scattering. A comparison with a low--scale parametrization shows that the model reproduces the gross features of the empirical structure functions. We also compute the leading twist contributions of the polarized structure functions $g_{1}(x)$ and $g_{2}(x)$ in this model. We compare the model predictions on these structure functions with data from the E143 experiment by GLAP evolving them appropriately.
Nucleon QCD sum rules in the instanton medium
International Nuclear Information System (INIS)
We try to find grounds for the standard nucleon QCD sum rules, based on a more detailed description of the QCD vacuum. We calculate the polarization operator of the nucleon current in the instanton medium. The medium (QCD vacuum) is assumed to be a composition of the small-size instantons and some long-wave gluon fluctuations. We solve the corresponding QCD sum rule equations and demonstrate that there is a solution with the value of the nucleon mass close to the physical one if the fraction of the small-size instantons contribution is ws ≈ 2/3
Deep inelastic scattering operators in meson-nucleon theory
International Nuclear Information System (INIS)
Nonrelativistic meson-nucleon theory of deep-inelastic scattering (DIS) of leptons on the deuteron is considered. Explicit expressions of nonrelativistic composed operators of DIS in the framework of the operator product expansion method are obtained in terms of interacting meson-nucleon fields. An analytic expression of the second moment of the structure functions (up to g2 accuracy( is obtained with particular emphasis on self-energy contributions and meson exchange currents (MEC). Deuteron moments are shown to be expressed in terms of constituent (nucleons and mesons) observables. The energy conservation law is restored by taking into account MEC
Deuteron–deuteron scattering above four-nucleon breakup threshold
Directory of Open Access Journals (Sweden)
A. Deltuva
2015-03-01
Full Text Available Deuteron–deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit Δ-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated.
Deuteron-deuteron scattering above four-nucleon breakup threshold
Deltuva, A
2015-01-01
Deuteron-deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit $\\Delta$-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated.
Deuteron–deuteron scattering above four-nucleon breakup threshold
Energy Technology Data Exchange (ETDEWEB)
Deltuva, A., E-mail: arnoldas.deltuva@tfai.vu.lt [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Goštauto 12, LT-01108 Vilnius (Lithuania); Fonseca, A.C. [Centro de Física Nuclear da Universidade de Lisboa, P-1649-003 Lisboa (Portugal)
2015-03-06
Deuteron–deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit Δ-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated.
Three dimensional imaging of the nucleon --- TMD (theory and phenomenology)
Liang, Zuo-tang
2015-01-01
This is intend to provide an overview of the theoretical and phenomenological parts of the TMD (Transverse Momentum Dependent parton distribution and fragmentation functions) studies. By comparing with the theoretical framework that we have for the inclusive deep inelastic lepton-nucleon scattering and the one-dimensional imaging of the nucleon, I try to outline what we need to do in order to construct a comprehensive theoretical framework for semi-inclusive reactions and the three dimensional imaging of the nucleon. After that, I try to give an overview of what we have already achieved and make an outlook for the future.
Correlation between observable of four nucleon system in two-body model
International Nuclear Information System (INIS)
The four nucleon system with effective nucleon-trinucleon interaction for s waves in states of spin Y = 0 and isospin Y = 0, is studied. The correlations between four nucleon systemn and scattering wavelength, binding energies and, coulomb energy of four nucleons are investigated by N/D method considering only the excited state. (M.C.K.)
Federal Laboratory Consortium — The last of Hanfordqaodmasdkwaspemas7ajkqlsmdqpakldnzsdflss nine plutonium production reactors to be built was the N Reactor.This reactor was called a dual purpose...
Nucleon Polarizabilities: from Compton Scattering to Hydrogen Atom
Hagelstein, Franziska; Pascalutsa, Vladimir
2015-01-01
We review the current state of knowledge of the nucleon polarizabilities and of their role in nucleon Compton scattering and in hydrogen spectrum. We discuss the basic concepts, the recent lattice QCD calculations and advances in chiral effective-field theory. On the experimental side, we review the ongoing programs aimed to measure the nucleon (scalar and spin) polarizabilities via the Compton scattering processes, with real and virtual photons. A great part of the review is devoted to the general constraints based on unitarity, causality, discrete and continuous symmetries, which result in model-independent relations involving nucleon polarizabilities. We (re-)derive a variety of such relations and discuss their empirical value. The proton polarizability effects are presently the major sources of uncertainty in the assessment of the muonic hydrogen Lamb shift and hyperfine structure. Recent calculations of these effects are reviewed here in the context of the "proton-radius puzzle". We conclude with summary...
Evidence for new nucleon resonances from electromagnetic meson production
Energy Technology Data Exchange (ETDEWEB)
Volker Burkert
2012-12-01
The study of nucleon resonances in electromagnetic meson production with the CLAS detector is discussed. The electromagnetic interaction is complementary to pion scattering in the exploration of the nucleon excitation spectrum. Higher mass states often decouple from the N{pi} channel and are not seen in {pi} N --> {pi} N. Photoproduction of mesons, such as K {Lambda}, {omega} p and {eta}' p may be more sensitive to many of these states. The CLAS detector, combined with the use of energy-tagged polarized photons and polarized electrons, as well as po- larized targets and the measurement of recoil polarization, are the tools needed for a comprehensive nucleon resonance program. Some of the recently published high statistics data sets had significant impact on further clarifying the nucleon excitation spectrum.
Two-nucleon transfer reactions with form factor models
International Nuclear Information System (INIS)
The theory of two-nucleon transfer reactions is considered. Nuclear reactions are considered with triton or 3He particles which are used as projectiles in stripping reactions and as detected particles in pick-up reactions. In each channel we have a four-particle problem, three of them are nucleons and the fourth is a heavy particle. These transfer reactions are studied on the basis of the generaled R-matrix method. Different channel functions of the sub-clusters in the triton and 3He particles are included. Model form factors are obtained and are used in two-nucleon transfer reactions. Differential cross-sections of different two-nucleon transfer reactions are calculated and are found in good agreement with the experimental data. The correct normalization and spectroscopic factors are obtained. (author)
Effective Lagrangian Approach to pion photoproduction from the nucleon
Fernandez-Ramirez, C; Udias, J M
2006-01-01
We present a pion photoproduction model on the free nucleon based on an Effective Lagrangian Approach (ELA) which includes the nucleon resonances ($\\Delta(1232)$, N(1440), N(1520), N(1535), $\\Delta (1620)$, N(1650), and $\\Delta (1700)$), in addition to Born and vector meson exchange terms. The model incorporates a new theoretical treatment of spin-3/2 resonances, first introduced by Pascalutsa, avoiding pathologies present in previous models. Other main features of the model are chiral symmetry, gauge invariance, and crossing symmetry. We use the model combined with modern optimization techniques to assess the parameters of the nucleon resonances on the basis of world data on electromagnetic multipoles. We present results for electromagnetic multipoles, differential cross sections, asymmetries, and total cross sections for all one pion photoproduction processes on free nucleons. We find overall agreement with data from threshold up to 1 GeV in laboratory frame.
Momentum and coordinate space three-nucleon potentials
International Nuclear Information System (INIS)
In this paper we give explicit formulae in momentum and coordinate space for the three-nucleon potentials due to ρ and π meson exchange, derived from off-mass-shell meson-nucleon scattering amplitudes which are constrained by the symmetries of QCD and by the experimental data. Those potentials have already been applied to nuclear matter calculations. Here we display additional terms which appear to be the most important for nuclear structure. The potentials are decomposed in a way that separates the contributions of different physical mechanisms involved in the meson-nucleon amplitudes. The same type of decomposition is presented for the π - π TM force: The Δ isobar, the chiral symmetry breaking and the nucleon pair terms are isolated
Energy Technology Data Exchange (ETDEWEB)
Rebreyend, D
2006-10-15
The photoproduction of mesons on the nucleon gives a direct access to its spectroscopy and is a promising way for the study of the structure of the nucleon. The GRAAL experiment uses a tagged and polarized photon beam produced through the Compton diffusion of laser photons on the electrons circulating in the ESRF storage ring. The combination of this photon beam and an efficient detection system has allowed a series of measurements concerning the photoproduction of light mesons on the proton and on the neutron. The first 4 chapters are dedicated to the nucleon spectroscopy: the nucleon models and their consequences on the excited levels are recalled, the experimental technique used is described and the difficulties due to the extraction of relevant data are presented. Highly accurate measurements of cross-sections, {sigma} asymmetry beams and resonance parameters have been performed. The last part is dedicated to the principle of the measurement of the electric dipole momentum of the neutron. (A.C.)
Nucleon transfer reactions in D.W.B.A
International Nuclear Information System (INIS)
The DWBA for one nucleon transfer reaction is described as simply and completely as possible to show the possibilities and limits of this method. The extraction of spectroscopic factors is described in the appendix. (authors)
Spectral asymmetries in nucleon sum rules at finite density
Furnstahl, R. J.
1993-01-01
Apparent inconsistencies between different formulations of nucleon sum rules at finite density are resolved through a proper accounting of asymmetries in the spectral functions between positive- and negative-energy states.
Majorana Dark Matter Cross Sections with Nucleons at High Energies
Jeong, Yu Seon; Reno, Mary Hall
2012-01-01
Non-relativistic dark matter scattering with nucleons is constrained by direct detection experiments. We use the XENON constraints on the spin-independent and spin-dependent cross section for dark matter scattering with nucleons to constrain a hypothetical Majorana fermionic dark matter particle's couplings to the Higgs boson and Z boson. In the procedure we illustrate the change in the dark matter nucleon cross section as one goes from non-relativistic, coherent scattering to relativistic, incoherent scattering. While the Z invisible decay width excludes directly couplings of dark matter to ordinary matter, by introducing a light Z' portal to the dark sector, a relatively large dark matter nucleon cross section can be preserved even with accelerator experiment constraints for dark matter with a mass of ~10 GeV
Review of Nucleon Decay Searches at Super-Kamiokande
Takhistov, Volodymyr
2016-01-01
Baryon number violation appears in many contexts. It is a requirement for baryogenesis and is a consequence of Grand Unified Theories (GUTs), which predict nucleon decay. Nucleon decay searches provide the most direct way to test baryon number conservation and also serve as a unique probe of GUT scale physics around $10^{14-16}$ GeV. Such energies cannot be reached directly by accelerators. However, they can be explored indirectly at large underground water Cherenkov (WC) experiments, which due to the size of their fiducial volume are highly sensitive to nucleon decays. We review searches for baryon number violating processes at the state of the art WC detector, the Super-Kamiokande. Analyses of the typically dominant non-SUSY and SUSY nucleon decay channels such as $p \\rightarrow (e^+, \\mu^+) \\pi^0$ and $p \\rightarrow \
Momentum and coordinate space three-nucleon potentials
Coon, S A
1993-01-01
In this paper we give explicit formulae in momentum and coordinate space for the three-nucleon potentials due to $\\rho$ and $\\pi$ meson exchange, derived from off-mass-shell meson-nucleon scattering amplitudes which are constrained by the symmetries of QCD and by the experimental data. Those potentials have already been applied to nuclear matter calculations. Here we display additional terms which appear to be the most important for nuclear structure. The potentials are decomposed in a way that separates the contributions of different physical mechanisms involved in the meson-nucleon amplitudes. The same type of decomposition is presented for the $\\pi - \\pi$ TM force: the $\\Delta$, the chiral symmetry breaking and the nucleon pair terms are isolated.
Transverse momentum distributions inside the nucleon from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Musch, Bernhard Ulrich
2009-05-29
Nucleons, i.e., protons and neutrons, are composed of quarks and gluons, whose interactions are described by the theory of quantum chromodynamics (QCD), part of the standard model of particle physics. This work applies lattice QCD to compute quark momentum distributions in the nucleon. The calculations make use of lattice data generated on supercomputers that has already been successfully employed in lattice studies of spatial quark distributions (''nucleon tomography''). In order to be able to analyze transverse momentum dependent parton distribution functions, this thesis explores a novel approach based on non-local operators. One interesting observation is that the transverse momentum dependent density of polarized quarks in a polarized nucleon is visibly deformed. A more elaborate operator geometry is required to enable a quantitative comparison to high energy scattering experiments. First steps in this direction are encouraging. (orig.)
Transverse momentum distributions inside the nucleon from lattice QCD
International Nuclear Information System (INIS)
Nucleons, i.e., protons and neutrons, are composed of quarks and gluons, whose interactions are described by the theory of quantum chromodynamics (QCD), part of the standard model of particle physics. This work applies lattice QCD to compute quark momentum distributions in the nucleon. The calculations make use of lattice data generated on supercomputers that has already been successfully employed in lattice studies of spatial quark distributions (''nucleon tomography''). In order to be able to analyze transverse momentum dependent parton distribution functions, this thesis explores a novel approach based on non-local operators. One interesting observation is that the transverse momentum dependent density of polarized quarks in a polarized nucleon is visibly deformed. A more elaborate operator geometry is required to enable a quantitative comparison to high energy scattering experiments. First steps in this direction are encouraging. (orig.)
Quasielastic production of polarized hyperons in antineutrino--nucleon reactions
Akbar, F; Athar, M Sajjad; Singh, S K
2016-01-01
We have studied the longitudinal and perpendicular polarizations of final hyperon($\\Lambda$,$\\Sigma$) produced in the antineutrino induced quasielastic charged current reactions on nucleon targets. The nucleon-hyperon transition form factors are determined from the experimental data on quasielastic $(\\Delta S =0)$ charged current (anti)neutrino--nucleon scattering and the semileptonic decay of neutron and hyperons assuming G--invariance, T--invariance and SU(3) symmetry. The vector transition form factors are obtained in terms of nucleon electromagnetic form factors for which various parameterizations available in literature have been used. A dipole parameterization for the axial vector form factor and the pseudoscalar transition form factor derived in terms of axial vector form factor assuming PCAC and GT relation extended to strangeness sector have been used in numerical evaluations. The flux averaged cross section and polarization observables corresponding to CERN Gargamelle experiment have been calculated...
On description of the direct nucleon decay of giant resonances
Chekomazov, G A; Urin, M H
1996-01-01
A semimicroscopical approach is formulated to describe the direct nucleon decay of various giant resonances in intermediate and heavy mass spherical nuclei. The approach consists in: (i) the exact continuum-RPA calculations for amplitudes of the reactions accompanied by excitation and the nucleon decay of the collective particle-hole states (doorway states); (ii) the Breit-Wigner parametrization of the RPA reaction-amplitudes in the vicinity of the giant giant-resonance energy and evaluation of the doorway-state parameter (the energy, entrance and partial nucleon, escape widths); (iii) the phenomenological consideration for the doorway-state coupling to many-particle configurations with the use of reasonable statistical assumptions and derivation on this base the expressions for the energy-averaged reaction amplitudes. The nuclear mean field and quasiparticle interaction are the input quantities for calculations. Examples of description for the direct nucleon decay of a number of giant resonances in the $^{20...
The parton distributions in nuclei and in polarized nucleons
International Nuclear Information System (INIS)
The emerging information was reviewed on the way quark and anti-quark, and gluon distributions are modified in nuclei relative to free nucleons. Some implications of the recent data on polarized leptoproduction are discussed. 27 refs., 6 figs
Quark Delocalization, Color Screening Model and Nucleon-Baryon Scattering
Wu, G; Teng, L; Wang, F; Goldman, T; Wu, Guang-han; Ping, Jia-Lun; Teng, Li-jian; Wang, Fan
2000-01-01
We apply the quark delocalization and color screening model to nucleon-baryon scattering. A semi-quantitative fit to N-N, N-Lambda and N-Sigma phase shifts and scattering cross sections is obtained without invoking meson exchange. Quarks delocalize reasonably in all of the different flavor channels to induce effective nucleon-baryon interactions with both a repulsive core and with an intermediate range attraction in the cases expected.
A no extensive statistical model for the nucleon structure function
Trevisan, Luis A.; Mirez, Carlos
2013-03-01
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.
a Nonextensive Statistical Model for the Nucleon Structure Function
Trevisan, Luis Augusto; Mirez, Carlos
2013-07-01
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalizations in the nucleon.
Nucleonic gauges in the Australian mining and exploration industries
International Nuclear Information System (INIS)
On-line and in-situ nucleonic analysis systems have found widespread application in the Australian metalliferous mineral and coal industries. The rapid and reliable response of these systems has led to improved exploration and better control of mining and mineral processing. This paper reviews both types of nucleonic control system (on-line and in-situ) available in Australian exploration and mining market. (author)
Hadronic parity violation in few-nucleon systems
International Nuclear Information System (INIS)
The interactions between nucleons contain a parity-violating component, which originates in the weak interaction between quarks and which is suppressed by a factor of approximately 10−7 compared to the dominant parity-conserving component. A theoretical framework based on effective field theory methods to analyze and interpret parity-violating interactions between nucleons is described and a number of applications are discussed
[Measurements of observables of pion-nucleon reactions]. Progress report
International Nuclear Information System (INIS)
This document reports the progress of the research of pion reactions. These include (1) a study to measure observables in the pion-nucleon system in the momentum interval 400 to 700 MeV/c, (2) differential cross section measurements at low energy for pion-nucleon charge exchange, and (3) elastic and inelastic scattering of π+- on 3H and 3He. Individual experiments will be indexed separately
Nucleon currents and frictional forces between highly excited nuclei
International Nuclear Information System (INIS)
A finite temperature Thomas-Fermi method has been used to study the nucleon transfer between two hot slabs of symmetric nuclear matter. Special attention has been paid to temperature effects neglected in earlier calculations. As a result, closed and ready-to-use formulas for the exchange and transfer nucleon flux at zero relative momentum are given as a function of the temperature T. We also present a rather detailed discussion of thermal properties of the semi-infinite slabs
Generalized Parton Distributions and the Spin Structure of the Nucleon
Ji, Xiangdong
2002-01-01
Generalized parton distributions are a new type of hadronic observables which has recently stimulated great interest among theorists and experimentalists alike. Introduced to delineate the spin structure of the nucleon, the orbital angular momentum of quarks in particular, the new distributions contain vast information about the internal structure of the nucleon, with the usual electromagnetic form factors and Feynman parton distributions as their special limits. While new perturbative QCD pr...
The two-nucleon problem in the Skyrme model
International Nuclear Information System (INIS)
We solve the partial differential equation pertaining to the baryon-number-two state in the Skyrme model with the product ansatz in a Born-Oppenheimer approach. The solution obeys exactly conservation of baryon number and has a clear definition for the baryon location. We find that soliton profiles are strongly distorted at short interbaryon separations and single-particle static observables are also affected. The nucleon-nucleon static interaction is calculated. (orig.)
Chiral restoration in excited nucleons versus SU(6)
International Nuclear Information System (INIS)
We compare axial charges of excited nucleons, as predicted by the chiral symmetry restoration picture, with the traditional, moderately successful for the ground-state baryons SU(6) symmetry. The axial charges of excited nucleons can (and will) be measured in lattice QCD simulations, and comparison of the lattice results with the two different symmetry schemes will give an insight on the origins of the excited hadron masses as well as on interrelations of chiral symmetry and confinement
Strange quark content of the nucleon and dark matter searches
Young, R. D.
2013-01-01
The strange quark scalar content plays an important role in both the description of nucleon structure and in the determination of dark matter direct detection cross sections. As a measure of the strange-quark contribution to the nucleon mass, the strange-quark sigma term (\\sigma_s) provides important insight into the nature of mass generation in QCD. The phenomenological determination of \\sigma_s exhibits a wide range of variation, with values suggesting that the strange quark contributes any...
Nucleon effective mass effects on the Pauli-blocking function
International Nuclear Information System (INIS)
The effects of nucleon effective mass on the Pauli-blocking function are worked out. We have shown that such effects on the quasi-deuteron mechanism of photonuclear absorption are rather relevant. The pauli-blocking function has been evaluated by applying a Monte Carlo calculation particularly suitable for simulation of intranuclear cascade process of intermediate-energy nuclear reactions. The nucleon binding in the photonuclear absorption mechanism is accordingly taken into account. (author)
Nucleon Spin Content in a Relativistic Quark Potential Model Approach
Institute of Scientific and Technical Information of China (English)
DONG YuBing; FENG QingGuo
2002-01-01
Based on a relativistic quark model approach with an effective potential U(r) = (ac/2)(1 + γ0)r2, the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the couplings between the Goldstone bosons and the nucleon. Different approaches to deal with the center of mass correction in the relativistic quark potential model approach are discussed.
Relativistic spectral function of nucleon in hot nuclear matter
Ghosh, Sabyasachi; Mallik, S.; Sarkar, Sourav
2010-01-01
We present a simple calculation of the nucleon self-energy in nuclear matter at finite temperature in a relativistic framework, using the real time thermal field theory. The imaginary parts of one-loop graphs are identified with discontinuities across the unitary and the Landau cuts. We find that in general both the cuts contribute significantly to the spectral function in the region of (virtual) nucleon mass usually considered, even though the unitary cut is ignored in the literature. Also o...
Volume Dependence of the Axial Charge of the Nucleon
Hall, N. L.; Thomas, A. W.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia); Zanotti, J. M.
2012-01-01
It is shown that the strong volume-dependence of the axial charge of the nucleon seen in lattice QCD calculations can be understood quantitatively in terms of the pion-induced interactions between neighbouring nucleons. The associated wave function renormalization leads to an increased suppression of the axial charge as the strength of the interaction increases, either because of a decrease in lattice size or in pion mass.
Spin structure of the nucleon and triangle anomaly
International Nuclear Information System (INIS)
It is shown that the gluon contribution to the sum rule for spin parton distribution functions which determines the spin of the nucleon is fixed by the axial Adler-Bell-Jackiw anomaly. The new sum rule is consistent with OCD evolution equations and predicts that quarks carry about 70% of the nucleon spin. The gluon contribution results in negative extra term to the Ellis-Jaffe sum rule for the structure function g1 which accounts for its disagreement with experiment
Progress in the calculation of nucleon transition form factors
Eichmann, Gernot
2016-01-01
We give a brief account of the Dyson-Schwinger and Faddeev-equation approach and its application to nucleon resonances and their transition form factors. We compare the three-body with the quark-diquark approach and present a quark-diquark calculation for the low-lying nucleon resonances including scalar, axialvector, pseudoscalar and vector diquarks. We also discuss the timelike structure of transition form factors and highlight the advantages of form factors over helicity amplitudes.
Quasi-coherent state of pions in the nucleon
Morishita, M; Morishita, Masanori; Arima, Masaki
2003-01-01
Making use of the quasi-coherent state developed by Eriksson et al., we can find a nucleon solution accompanied by the pion field with trivial topology. We compare our approach with other related works, and examine a coherent state description of pions in the baryon structure. Our solution suggests a kind of nucleon resonance due to the topological change of pion field without the usual quark excitation.
Experimental studies of nucleon-nucleon and pion-nucleus interactions at intermediate energies
International Nuclear Information System (INIS)
This report summarizes the work on experimental research in intermediate energy nuclear and particle physics carried out by New Mexico State University in 1988--91. Most of these studies have involved investigations of neutron-proton and pion-nucleus interactions. The neutron-proton research is part of a program of studies of interactions between polarized nucleons that we have been involved with for more than ten years. Its purpose has been to help complete the determination of the full set of ten complex nucleon-nucleon amplitudes at energies up to 800 MeV, as well as to continue investigating the possibility of the existence of dibaryon resonances. The give complex isospin-one amplitudes have been fairly well determined, partly as a result of this work. Our work in this period has involved measurements and analysis of data on elastic scattering and total cross sections for polarized neutrons on polarized protons. The pion-nucleus research continues our studies of this interaction in regions where it has not been well explored. One set of experiments includes studies of pion elastic and double-charge-exchange scattering at energies between 300 and 550 MeV, where our data is unique. Another involves elastic and single-charge-exchange scattering of pions from polarized nuclear targets, a new field of research which will give the first extensive set of information on spin-dependent pion-nucleus amplitudes. Still another involves the first set of detailed studies of the kinematic correlations among particles emitted following pion absorption in nuclei
International Nuclear Information System (INIS)
The molecular orbitals of the nucleon(s) in nucleus-nucleus collisions are dynamically defined as a linear combination of nucleon single-particle orbits (LCNO) in a rotating frame by using the coupled-reaction-channel (CRC) theory. Nucleon molecular orbitals and the promotions of nucleon, - especially due to the Landau-Zener radial coupling are discussed with the method above mentioned. (author)
The cross section minima in elastic Nd scattering a "smoking gun" for three nucleon force effects
Witala, H; Hüber, D; Golak, J; Kamada, H
1998-01-01
Neutron-deuteron elastic scattering cross sections are calculated at different energies using modern nucleon-nucleon interactions and the Tucson-Melbourne three-nucleon force adjusted to the triton binding energy. Predictions based on NN forces only underestimate nucleon-deuteron data in the minima at higher energies starting around 60 MeV. Adding the three-nucleon forces fills up those minima and reduces the discrepancies significantly.
Mean Field Calculation of Thermal Properties of Simple Nucleon Matter on a Lattice
Abe, T.; Seki, R.; Kocharian, A. N.
2003-01-01
Thermal properties of single species nucleon matter are investigated assuming a simple form of the nucleon-nucleon interaction. The nucleons are placed on a cubic lattice, hopping from site to site and interacting through a spin-dependent force, as in the extended, attractive Hubbard model. A mean field calculation in the Hartree-Fock Bogoliubov approximation suggests that the superfluid ground state generated by strong nucleon pairing undergoes a second-order phase transition to a normal sta...
Scattering integral equations and four nucleon problem. Four nucleon bound states and scattering
International Nuclear Information System (INIS)
Existing results from the application of integral equation technique four-nucleon bound states and scattering are reviewed. The purpose of this review is to provide a clear and elementary introduction in the integral equation method and to demonstrate its usefulness in physical applications. Developments in the actual numerical solutions of Faddeev-Yakubovsky type equations are such that a detailed comparison can be made with experiment. Bound state calculations indicate that a nonrelativistic description with pairwise nuclear forces does not suffice and additional degrees of freedom are noted
In-medium NN interactions and nucleon and meson masses studied with nucleon knockout reactions
International Nuclear Information System (INIS)
Spin observables have been measured for (p, 2p) reactions aiming at studying medium effects on NN interactions in nuclear field. Observed strong density-dependent reduction of the analyzing power is consistent with a model calculation where reduction of nucleon and meson masses are taken into account. On the other hand, calculations with g-matrices in the Shroedinger framework does not predict the reduction. The spin-transfer coefficients, which data are not reproduced by the model calculation, are found to be sensitive to reduction rate of each meson mass and have a possibility to test scaling lows in mass reductions
The Spin Structure of the nucleon
Deur, Alexandre
2015-10-01
This talk will review the status of the experiments studying the spin structure of the nucleon. After a brief overview of the topics, I will focus on the program measuring the generalized Gerasimov-Drell-Hearn (GDH) sum, in the context of connecting the effective descriptions of the strong force at long distances to its fundamental partonic description at short distances. The generalized GDH sum rule is a theoretical relation valid at any distance. Consequently, it can be an Ariadne's thread to follow to understand how the transition between the partonic to hadronic descriptions happens. Measurements at intermediate and short distances have been made available in the 1990s and 2000s. Long distance results are being now finalized. With them, a large part of this experimental program will be completed. I will give the status of the measurements at long distances. I will then conclude the talk with a practical example on how the GDH data are used to connect the fundamental and effective descriptions of the strong force. Such example demonstrates how the generalized GDH program is bearing fruits.
Structure and spin of the nucleon
International Nuclear Information System (INIS)
Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions (TDM) and Generalized Parton Distributions (GPD), were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements. (author)
Electromagnetic interactions with nucleons and nuclei
International Nuclear Information System (INIS)
Our primary research effort continues to be at the LEGS project at Brookhaven National Laboratory. The LEGS facility has made a transition in the last year from a combination of experiment and facility construction to full time experimental work. The first experiment, photodisintegration of the deuteron with polarized γ rays, is completed and partially published. A second experiment, 3He(γ,NN), has also been completed and analysis has begun. We except to begin two more experiments in the next year. Other research efforts are primarily related to CEBAF and this work is growing, since major CEBAF experimental equipment is now being constructed. We are heavily involved in the CLAS collaboration in Hall B which will build the CEBAF Large Acceptance Spectrometer. Our contributions to the CEBAF experimental program and equipment construction are described. The 3He(γ, NN) experiment at LEGS was the second use, in a new format, of the University of Virginia Nucleon Detector System. It is now a fully developed system. We also describe a new area of instrument development, applications of waveshifting optical fibers to novel position sensitive detectors for neutral particles
Structure and Spin of the Nucleon
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut A. [JLAB
2014-03-01
Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Light flavor asymmetry of nucleon sea
Energy Technology Data Exchange (ETDEWEB)
Song, Huiying; Zhang, Xinyu [Peking University, School of Physics and State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Ma, Bo-Qiang [Peking University, School of Physics and State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Peking University, Center for High Energy Physics, Beijing (China)
2011-02-15
The light flavor antiquark distributions of the nucleon sea are calculated in the effective chiral quark model and compared with experimental results. The contributions of the flavor-symmetric sea-quark distributions and the nuclear EMC effect are taken into account to obtain the ratio of Drell-Yan cross sections {sigma}{sup pD}/2{sigma}{sup pp}, which can match well with the results measured in the FermiLab E866/NuSea experiment. The calculated results also match the anti d(x)- anti u(x) measured in different experiments, but unmatch the behavior of anti d(x)/ anti u(x) derived indirectly from the measurable quantity {sigma}{sup pD}/2{sigma}{sup pp} by the FermiLab E866/NuSea Collaboration at large x. We suggest to measure again anti d(x)/ anti u(x) at large x from precision experiments with careful treatment of the experimental data. We also propose an alternative procedure for experimental data treatment. (orig.)
Instrumentation of KGF nucleon decay experiment
International Nuclear Information System (INIS)
The Kolar Gold Fields nucleon decay experiments have been in operation with a 140 ton detector (phase I) since 1980 and with a 350 ton detector (phase II) since 1985. These detectors come under the category of fine-grain-tracking calorimeters, in which measurements are made on the ionisation of charged particles as they traverse the detector. The two detectors have a similar design and the special features of the upgraded phase II are given in detail. The basic detector elements are 6 m long proportional counters of square cross-section arranged in 60 horizontal layers. An iron plate of 6 mm thickness is sandwiched between every two consecutive layers of counters. A total of 4000 proportional counters have been manufactured, tested and calibrated. Each of these counters is separately instrumented to process pulses from the central anode wire. A Z-80 based microprocessor farm has been implemented in parallel processing scheme for faster processing of event data. The technical details of the set-up are reported. (author). 6 refs., 17 figs
Structure and spin of the nucleon
Avakian, H.
2014-03-01
Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Electromagnetic Studies of Mesons, Nucleons, and Nuclei
Energy Technology Data Exchange (ETDEWEB)
Baker, Oliver K.
2013-08-20
Professor Baker was a faculty member at Hampton University in Hampton, Virginia, and, jointly, a Staff Physicist at Jefferson Lab in nearby Newport News from September 1989 to July 2006. The Department of Energy (DOE) funded the grant DE-FG02-97ER41035 Electromagnetic Studies of Mesons, Nucleons, and Nuclei, while Baker was in this joint appointment. Baker sent a closeout report on these activities to Hampton University’s Sponsored Research Office some years ago, shortly after joining Yale University in 2006. In the period around 2001, the research grant with Baker as the Principal Investigator (PI) was put under the supervision of Professor Liguang Tang at Hampton University. Baker continued to pursue the research while in this join appointment, however the administrative responsibilities with the DOE and with Hampton University rested with Professor Tang after 2001, to my recollection. What is written in this document is from Baker’s memory of the research activities, which he has not pursued since joining the Yale University faculty.
International Nuclear Information System (INIS)
A complete measurement of the polarization transfer observables has been made for the first time in the (p,p') reaction at intermediate energies. Measurements are reported for the 12C(p,p') 12C reaction to the 1+, T = 0(12.71 MeV) and 1+, T = 1(15.11 MeV) states at 500 MeV at laboratory scattering angles of 3.50, 5.50, 7.50, and 12.00. Linear combinations of these observables are shown to exhibit a very selective dependence on the isoscalar and isovector spin-dependent components of the nucleon-nucleon interaction. To the extent of the validity of the single collision approximation, these amplitudes are compared directly to the free nucleon-nucleon amplitudes at small momentum transfers
International Nuclear Information System (INIS)
In the Cloudy Bag Model hadrons are treated as quarks confined in an M.I.T. bag that is surrounded by a cloud of pions. Computations of the charge and magnetism distributions of nucleons and baryons, pion-nucleon scattering, and the strong and electromagnetic decays of mesons are discussed. Agreement with experimental results is excellent if the nucleon bag radius is in the range between 0.8 and 1.1 fm. Underlying qualitative reasons which cause the pionic corrections to be of the obtained sizes are analyzed. If bags are of such reasonably large sizes, nucleon bags in nuclei will often come into contact. As a result one needs to consider whether explicit quark degrees of freedom are relevant for Nuclear Physics. To study such possibilities a model which treats a nucleus as a collection of baryons, pions and six-quark bags is discussed. In particular, the short distance part of a nucleon-nucleon wave function is treated as six quarks confined in a bag. This approach is used to study the proton-proton weak interaction, the asymptotic D to S state ratio of the deuteron, the pp → dπ reaction, the charge density of /sup 3/He, magnetic moments of /sup 3/He and /sup 3/H and, the /sup 3/He-/sup 3/H binding energy difference. It is found that quark effects are very relevant for understanding nuclear properties
Energy Technology Data Exchange (ETDEWEB)
Bertini, M.
1995-05-12
This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F{sub 2}) and polarized (g{sub 1}) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F{sub 2} and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions g{sup p,n,d} and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends.
Nucleon-nucleon interactions in the double folding model for fusion reactions
Institute of Scientific and Technical Information of China (English)
Zhang Gao-Long; Liu Hao; Le Xiao-Yun
2009-01-01
Nucleus-nucleus potentials are determined in the framework of double folding model for M3Y-Reid and M3Y-Paris effective nucleon nucleon (NN) interactions. Both zero-range and finite-range exchange parts of NN interactions are considered in the folding procedure. In this paper the spherical projectile-spherical target system 16O+208Pb is selected for calculating the barrier energies, fusion cross sections and barrier distributions with the density-independent and density-dependcnt NN interactions on the basis of M3Y-Reid and M3Y-Paris NN interactions. The barrier energies become lower for Paris NN interactions in comparison with Reid NN interactions, and also for finite-range exchange part in comparison with zero-range exchange part. The density-dependent NN interactions give similar fusion cross sections and barrier distributions, and the density-independent NN interaction causes the barrier distribution moving to a higher position. However, the density-independent Reid NN interaction with zero-range exchange part gives the lowest fusion cross sections. We find that the calculated fusion cross sections and the barrier distributions are in agreement with the experimental data after rcnormalization of the nuclear potential due to coupled-channel effect.
Block-diagonal similarity renormalization group and effective nucleon-nucleon interactions
Szpigel, S.; Timóteo, V. S.; Ruiz Arriola, E.
2016-04-01
We apply the block-diagonal similarity renormalization group to a simple toy-model for the nucleon-nucleon (NN) interaction in the 1 S 0 channel, aiming to analyze the complementarity between the explicit and the implicit renormalization approaches in nuclear physics. By explicit renormalization we mean the methods based on the wilsonian renormalization group in which high-energy modes above a given cutoff scale are integrated out while their effects are replaced by scale dependent effective interactions consistently generated in the process. We call implicit renormalization the usual procedure of cutoff effective theories in which the high-energy modes above the cutoff scale are simply removed and their effects are included through parametrized cutoff dependent counterterms whose strengths are fixed by fitting low-energy data. We compare the effective interactions obtained in both schemes and find a wide range of cutoff scales where they overlap. We further analyze the role played by the one-pion exchange (OPE) considering a δ-shell plus OPE representation for the NN interaction.
Have nucleon decays already been seen?
International Nuclear Information System (INIS)
Within the framework of the classical theory of general relativity nothing remarkable is expected to happen to an observer falling into a large black hole other than the curious circumstance that after the observer crosses a certain surface, the 'event horizon', he can no longer communicate with the outside world. Although this prediction has been widely accepted in the physics community, it is inconsistent with quantum mechanics because it conflicts with the need for a universal time to define Schroedinger's equation. It has been pointed out [Philos. Mag. B 281 (2001) 235, Int. J. Mod. Phys. A 18 (2003) 831] that this inconsistency can be avoided if it is assumed that as the surface where general relativity predicts that the event horizon would be located is approached, the redshift does not actually go to infinity, but instead undergoes a continuous phase transition to a de Sitter phase where the vacuum energy is much larger than the cosmological vacuum energy. Although we do not have a fundamental theory of such a phase transition, many features of quantum phase transitions are universal. This universality allows us to make predictions concerning the behavior of matter as it encounters the quantum critical region that replaces the event horizon. One of these predictions is that the nucleons falling onto the critical surface will decay directly into multi-MeV leptons and gamma rays with a characteristic spectrum. As it happens there are some hints from the spectra of cosmic gamma ray bursts and observations of positrons from the center of our galaxy that this is correct
Induced terms of weak nucleon currents
International Nuclear Information System (INIS)
This paper reports on measurements of the weak magnetism form factor in the mass A = 12 system that have been continued for further critical tests of the conserved vector current hypothesis for the weak nucleon currents. With this proof confirmed, the non existence of the G-parity irregular induced tensor term in axial currents is extracted from the difference of the alignment correlation coefficients of the system by subtracting the weak magnetism term. In spite of such importance, available data from the spectral shapes of the system besides the analogue γ-ray width were only two. Although results of the difference of the β±-ray spectral shape factors agreed within the errors, those individual data for β- or β+ decay showed appreciable discrepancies. Possible reasons for these have not been clear yet, however, the major one of them was distortions of β-ray pulse-height spectra due to the scattering of electrons by experimental equipments. In this meaning measurements using such scattering free equipments are required. Regarding the alignment correlation coefficient, further studies on the limitation of the applicability of the G-parity conservation law and the soft pion effects in the time like component of the main axial currant have been continued. Also this difference of the coefficients can be an independent and good probe to study the strong form of CVC, if the induced tensor term is negligible. For these purposes the techniques developed for the measurements at Osaka have recently been improved further, especially in the creation of the spin alignment converted from polarization of 12B and 12N nuclei
Nuclear data needs for fusion reactors
International Nuclear Information System (INIS)
The nuclear design of fusion reactor components (e.g., first wall, blanket, shield, magnet, limiter, divertor, etc.) requires an accurate prediction of the radiation field, the radiation damage parameters, and the activation analysis. The fusion nucleonics for these tasks are reviewed with special attention to point out nuclear data needs and deficiencies which effect the design process. The main areas included in this review are tritium breeding analyses, nuclear heating calculations, radiation damage in reactor components, shield designs, and results of uncertainty analyses as applied to fusion reactor studies. Design choices and reactor parameters that impact the neutronics performance of the blanket are discussed with emphasis on the tritium breeding ratio. Nuclear data required for kerma factors, shielding analysis, and radiation damage are discussed. Improvements in the evaluated data libraries are described to overcome the existing problems
Hard breakup of two nucleons from the 3He nucleus
International Nuclear Information System (INIS)
We investigate a large angle photodisintegration of two nucleons from the 3He nucleus within the framework of the hard rescattering model (HRM). In the HRM a quark of one nucleon knocked out by an incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with large relative momentum. Assuming the dominance of the quark-interchange mechanism in a hard nucleon-nucleon scattering, the HRM allows the expression of the amplitude of a two-nucleon breakup reaction through the convolution of photon-quark scattering, NN hard scattering amplitude, and nuclear spectral function, which can be calculated using a nonrelativistic 3He wave function. The photon-quark scattering amplitude can be explicitly calculated in the high energy regime, whereas for NN scattering one uses the fit of the available experimental data. The HRM predicts several specific features for the hard breakup reaction. First, the cross section will approximately scale as s-11. Second, the s11 weighted cross section will have the shape of energy dependence similar to that of s10 weighted NN elastic scattering cross section. Also one predicts an enhancement of the pp breakup relative to the pn breakup cross section as compared to the results from low energy kinematics. Another result is the prediction of different spectator momentum dependencies of pp and pn breakup cross sections. This is due to the fact that the same-helicity pp-component is strongly suppressed in the ground state wave function of 3He. Because of this suppression the HRM predicts significantly different asymmetries for the cross section of polarization transfer NN breakup reactions for circularly polarized photons. For the pp breakup this asymmetry is predicted to be zero while for the pn it is close to (2/3).
Pellin, M. J.; Yacout, Abdellatif M.; Mo, Kun; Almer, Jonathan; Bhattacharya, S.; Mohamed, Walid; Seidman, D.; Ye, Bei; Yun, D.; Xu, Ruqing; Zhu, Shaofei
2016-04-01
The combination of MeV/Nucleon ion irradiation (e.g. 133 MeV Xe) and high energy synchrotron x-ray characterization (e.g. at the Argonne Advanced Photon Source, APS) provides a powerful characterization method to understand radiation effects and to rapidly screen materials for the nuclear reactor environment. Ions in this energy range penetrate ∼10 μm into materials. Over this range, the physical interactions vary (electronic stopping, nuclear stopping and added interstitials). Spatially specific x-ray (and TEM and nanoindentation) analysis allow individual quantification of these various effects. Hard x-rays provide the penetration depth needed to analyze even nuclear fuels. Here, this combination of synchrotron x-ray and MeV/Nucleon ion irradiation is demonstrated on U-Mo fuels. A preliminary look at HT-9 steels is also presented. We suggest that a hard x-ray facility with in situ MeV/nucleon irradiation capability would substantially accelerate the rate of discovery for extreme materials.
The nucleon thermal width due to pion-baryon loops and its contribution in Shear viscosity
Ghosh, Sabyasachi
2015-01-01
In the real-time thermal field theory, the standard expression of shear viscosity for the nucleonic constituents is derived from the two point function of nucleonic viscous stress tensors at finite temperature and density. The finite thermal width or Landau damping is traditionally included in the nucleon propagators. This thermal width is calculated from the in-medium self-energy of nucleon for different possible pion-baryon loops. The dynamical part of nucleon-pion-baryon interactions are taken care by the effective Lagrangian densities of standard hadronic model. The shear viscosity to entropy density ratio of nucleonic component decreases with the temperature and increases with the nucleon chemical potential. However, adding the contribution of pionic component, total viscosity to entropy density ratio also reduces with the nucleon chemical potential when the mixing effect between pion and nucleon components in the mixed gas is considered. Within the hadronic domain, viscosity to entropy density ratio of ...
Search for Nucleon Decays in Super-Kamiokande
International Nuclear Information System (INIS)
Grand Unified Theories (GUTs) is motivated by merging of the coupling constants of the strong, weak, and electromagnetic forces at a large energy scale (∼1016 GeV), which is out of the reach of accelerators. One of the other general features of GUTs is that they allow lepton and baryon number violations and they predict instability of nucleons. Then nucleon decay experiments are the direct probe for GUTs. The Super-Kamiokande (SK) is a water Cherenkov detector which keeps running to detect nucleon decays with large mass. There are no other nucleon decay detectors which have as long exposure as SK. The results of nucleon decay search based on 173 kton year (1996-2008) will be presented in the conference.The favored decay mode in GUTs based on SU(5) symmetry is p→e+ π0. On the other hand, p→ν K+ is favored by SUSY GUTs model. Those two modes will be mainly discussed. (authors)
Dispersion-theoretical analysis of the nucleon electromagnetic form factors
International Nuclear Information System (INIS)
The structure of the proton and the neutron is of fundamental importance for the study of the strong interaction dynamics over a wide range of momentum transfers. The nucleon form factors encode information on the internal structure of the nucleon as probed by the electromagnetic interaction, and, to a certain extent, reflect the charge and magnetisation distributions within the proton and the neutron. In this thesis we report on our investigation of the electromagnetic form factors of the proton and the neutron with dispersion relation techniques, including known experimental input on the ππ, K anti K and the ρπ continua and perturbative QCD constraints. We include new experimental data on the pion form factor and the nucleon form factors in our simultaneous analysis of all four form factors in both the space- and the timelike regions for all momentum transfers, and perform Monte- Carlo sampling in order to obtain theoretical uncertainty bands. Finally, we discuss the implications of our results on the pion cloud of the nucleon, the nucleon radii and the Okubo-Zweig-Iizuka rule, and present our results of a model-independent approach to estimating two-photon effects in elastic electron-proton scattering. (orig.)
Strong coupling constant of negative parity nucleon with $\\pi$ meson in light cone QCD sum rules
Aliev, T M; Savcı, M
2016-01-01
We estimate strong coupling constant between the negative parity nucleons with $\\pi$ meson within the light cone QCD sum rules. A method for eliminating the unwanted contributions coming from the nucleon--nucleon and nucleon--negative parity nucleon transition is presented. It is observed that the value strong coupling constant of the negative parity nucleon $N^\\ast N^\\ast \\pi$ transition is considerably different from the one predicted by the 3--point QCD sum rules, but is quite close to the coupling constant of the positive parity $N N \\pi$ transition.
International Nuclear Information System (INIS)
The Reactor Physics and MYRRHA Department of SCK-CEN offers expertise in various areas of reactor physics, in particular in neutronics calculations, reactor dosimetry, reactor operation, reactor safety and control and non-destructive analysis of reactor fuel. This expertise is applied in the Department's own research projects in the VENUS critical facility, in the BR1 reactor and in the MYRRHA project (this project aims at designing a prototype Accelerator Driven System). Available expertise is also used in programmes external to the Department such as the reactor pressure steel vessel programme, the BR2 reactor dosimetry, and the preparation and interpretation of irradiation experiments by means of neutron and gamma calculations. The activities of the Fuzzy Logic and Intelligent Technologies in Nuclear Science programme cover several domains outside the department. Progress and achievements in these topical areas in 2000 are summarised
International Nuclear Information System (INIS)
SCK-CEN's Reactor Physics and MYRRHA Department offers expertise in various areas of reactor physics, in particular in neutron and gamma calculations, reactor dosimetry, reactor operation and control, reactor code benchmarking and reactor safety calculations. This expertise is applied in the Department's own research projects in the VENUS critical facility, in the BR1 reactor and in the MYRRHA project (this project aims at designing a prototype Accelerator Driven System). Available expertise is also used in programmes external to the Department such as the reactor pressure steel vessel programme, the BR2 materials testing reactor dosimetry, and the preparation and interpretation of irradiation experiments by means of neutron and gamma calculations. The activities of the Fuzzy Logic and Intelligent Technologies in Nuclear Science programme cover several domains outside the department. Progress and achievements in these topical areas in 2001 are summarised
Energy Technology Data Exchange (ETDEWEB)
Ait Abderrahim, A
2001-04-01
The Reactor Physics and MYRRHA Department of SCK-CEN offers expertise in various areas of reactor physics, in particular in neutronics calculations, reactor dosimetry, reactor operation, reactor safety and control and non-destructive analysis of reactor fuel. This expertise is applied in the Department's own research projects in the VENUS critical facility, in the BR1 reactor and in the MYRRHA project (this project aims at designing a prototype Accelerator Driven System). Available expertise is also used in programmes external to the Department such as the reactor pressure steel vessel programme, the BR2 reactor dosimetry, and the preparation and interpretation of irradiation experiments by means of neutron and gamma calculations. The activities of the Fuzzy Logic and Intelligent Technologies in Nuclear Science programme cover several domains outside the department. Progress and achievements in these topical areas in 2000 are summarised.
Studies of nucleon-nucleon potentials with pp- and np-Bremsstrahlung
International Nuclear Information System (INIS)
A comprehensive study of pp and np bremsstrahlung based upon the potential model formalism was initiated to explore properties of two nucleon t-matrices. Underlying potentials of t-matrices either were generated by Gelfand-Levitan-Marchenko inversion of the latest NN phase shifts or are the Paris and Bonn-R potentials. The bremsstrahlung amplitudes associated with external, internal and exchange currents, by exact treatment of the Coulomb potential in on- and half-off-shell t-matrices, and the relativistic spin corrections were all computed and for both coplanar and non coplanar geometries. The results are a successful analysis of ppγ TRIUMF data and allow us to set experimental boundaries for planned new experiments. They also give a perspective of the off-shell t-matrix information inherent in this reaction. (orig.)
International Nuclear Information System (INIS)
We investigate giant resonances of spherical nuclei on the basis of the Argonne V18 potential after unitary transformation within the similarity renormalization group or the unitary correlation operator method supplemented by a phenomenological three-body contact interaction. Such Hamiltonians can provide a good description of ground-state energies and radii within Hartree–Fock plus low-order many-body perturbation theory. The standard random phase approximation is applied here to calculate the isoscalar monopole, isovector dipole, and isoscalar quadrupole excitation modes of the 40Ca, 90Zr, and 208Pb nuclei. Thanks to the inclusion of the three-nucleon interaction and despite the minimal optimization effort, a reasonable agreement with experimental centroid energies of all three modes has been achieved. The role and scope of the Hartree–Fock reference state in RPA methods are discussed. (paper)
Nucleon-induced fission at intermediate energies
International Nuclear Information System (INIS)
The absence of a satisfactory theoretical description to predict isotope yields as well as the need for experimental fragment mass and charge distributions at intermediate-energies form the motivation of this work. Like the objects under study, the research presented in this thesis consists two main parts. Part 1 concerns an activation experiment that has been performed at the 'Kernfysisch Versneller Instituut' (Nuclear Physics Accelerator Institute) in Groningen, Netherlands, using the AGOR cyclotron. Fission product yields have been measured resulting from 190 MeV proton-induced fission of natW, 197Au, natPb, 208Pb and 232Th. In Chapter 2 the experimental set up is discussed, followed in Chapter 3 by a description of the data analysis. The results on the reconstructed mass yields and the total fission cross sections are presented in Chapter 4. Part 2 is of a theoretical nature. The objective is to compute fission product mass yields from intermediate-energy nucleon-induced reactions. In the approach presented here, two stages can be distinguished. In the first stage the fission cross section is determined for the various fissioning isotopes as a function of their excitation energy in competition with other processes like pre-equilibrium decay and particle evaporation. ALICE-91 is a nuclear reaction code that takes care of this first stage. The second stage consists of constructing the total fission-fragment mass and charge distributions from the different contributions of all the equilibrated fissioning systems. Hence, a model is needed that gives a prediction for the fission-product mass yields in a large range of mass, charge, and excitation energy of the fissioning nucleus. For this purpose, the multi-modal random neck-rupture model by Brosa is extended with temperature-dependent shell and pairing corrections and a temperature-dependent LDM. The combination of ALICE-91 and the modified Brosa approach is used for the analysis of the experiments given in the
International Nuclear Information System (INIS)
Kaon production in heavy-ion collisions at bombarding energies below the nucleon-nucleon threshold is highly interesting. It can be related to the time evolution of the nuclear density during the collision which, in turn, could provide information on the Equation of State (EOS) of the nuclear matter at high densities and/or high temperatures. It could also help elucidating the question of whether subthreshold kaon production is a collective process or can still be explained by elementary baryon-baryon processes. In a first step, we give a review of models used for studying kaon production and we discuss the different parametrizations of the elementary kaon production cross-sections. In the second step, we study kaon production in the framework of the nuclear Boltzmann equation. This study shows that kaon production is very sensitive to the elementary cross-sections but not sufficiently to the mean field to determine accurately the EOS. We have then studied kaon production in the framework of the Boltzmann-Langevin equation. This approach goes beyond the average description of the Boltzmann equation by incorporating fluctuations due to high order correlations. To simulate this equation, we have developed an original method based on the projection of fluctuations on multipole moments of the momentum distribution. This study shows that large fluctuations appear in the early stages of the collision. It also shows that fluctuations, when incorporated into the equation of motion, substantially increase the kaon production cross-sections. In the last part, we have developed a model based on the results of the simulations of Boltzmann and Boltzmann-Langevin approaches to study kaon production far below the threshold. This model allows to evaluate kaon production cross-sections at energies as low as 100 MeV/n. Our results for the Ca + Ca collision are in good agreement with experimental data
Shaw, J
2013-01-01
Reactor Operation covers the theoretical aspects and design information of nuclear reactors. This book is composed of nine chapters that also consider their control, calibration, and experimentation.The opening chapters present the general problems of reactor operation and the principles of reactor control and operation. The succeeding chapters deal with the instrumentation, start-up, pre-commissioning, and physical experiments of nuclear reactors. The remaining chapters are devoted to the control rod calibrations and temperature coefficient measurements in the reactor. These chapters also exp
Russell, Charles R
2013-01-01
Reactor Safeguards provides information for all who are interested in the subject of reactor safeguards. Much of the material is descriptive although some sections are written for the engineer or physicist directly concerned with hazards analysis or site selection problems. The book opens with an introductory chapter on radiation hazards, the construction of nuclear reactors, safety issues, and the operation of nuclear reactors. This is followed by separate chapters that discuss radioactive materials, reactor kinetics, control and safety systems, containment, safety features for water reactor
Spin-isospin selectivity in three-nucleon forces
Mardanpour, H; Benard, R; Biegun, A; Eslami-Kalantari, M; Joulaeizadeh, L; Kalantar-Nayestanaki, N; Kiš, M; Kistryn, St; Kozela, A; Kuboki, H; Maeda, Y; Mahjour-Shafiei, M; Messchendorp, J G; Miki, K; Noji, S; Ramazani-Moghaddam-Arani, A; Sakai, H; Sasano, M; Sekiguchi, K; Stephan, E; Sworst, R; Takahashi, Y; Yako, K
2009-01-01
Precision data are presented for the break-up reaction, $^2{\\rm H}(\\vec p,pp)n$, within the framework of nuclear-force studies. The experiment was carried out at KVI using a polarized-proton beam of 190 MeV impinging on a liquid-deuterium target and by exploiting the detector, BINA. Some of the vector-analyzing powers are presented and compared with state-of-the-art Faddeev calculations including three-nucleon forces effect. Significant discrepancies between the data and theoretical predictions were observed for kinematical configurations which correspond to the $^2{\\rm H}(\\vec p,^2$He$)n$ channel. These results are compared to the $^2{\\rm H}(\\vec p,d)p$ reaction to test the isospin sensitivity of the present three-nucleon force models. The current modeling of two and three-nucleon forces is not sufficient to describe consistently polarization data for both isospin states.
High Energy Break-Up of Few-Nucleon Systems
Sargsian, Misak
2008-03-01
We discus recent developments in theory of high energy two-body break-up reactions of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon by the outgoing two nucleons. Within HRM we discuss hard break-up reactions involving 2D and 3He targets. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.
High Energy Break-Up of Few-Nucleon Systems
Sargsian, Misak M
2008-01-01
We discus recent developments in theory of high energy two-body break-up reactions of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon by the outgoing two nucleons. Within HRM we discuss hard break-up reactions involving $^2D$ and $^3He$ targets. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.
Hunting for the Remaining Spin in the Nucleon
Ji, X
1996-01-01
This talk consists of four parts. In part one, I give an elementary discussion on constructing a Lorentz-invariant spin sum rule for the nucleon. In part two, I discuss a gauge-dependent spin sum rule, explore its relation with the polarized gluon distribution, and introduce the complete evolution equation for the spin structure. In part three, I consider a gauge-invariant spin sum rule and the related evolution equation. The solution of the equation motivates the possibility that half of the nucleon spin may be carried by gluons at low energy scales. In the final part, I discuss deeply-virtual Compton scattering as a possible way to measure the canonical orbital angular momentum of quarks in the nucleon.
Chiral symmetry effect on the pion-nucleon coupling constant
International Nuclear Information System (INIS)
In this work we study the effects of chiral symmetry in the pion-nucleon coupling constant in the context of the linear σ- model. First, we introduce the linear σ-model and we discuss the phenomenological hypothesis of CVC and PCAC. Next, we calculate the coupling constant g+πNN(q2) and the nucleon pionic mean square radius considering the contribution of all the diagrams up to one-loop in the framework of the linear σ-model for different values of the mass of the sigma meson and we compare them with the phenomenological form factors. Finally we make an extension of the linear σ-model that consists of taking into account the mass differences of ions and nucleons into the Lagrangian of the model, to study the change dependence of gπnn (q2) and of the mean square radius. (author)
The two-nucleon t-matrices from inverse scattering
International Nuclear Information System (INIS)
The Marchenko inverse-scattering method has been used to determine the input potential functions to Lippmann-Schwinger equations for the two-nucleaon t-matrices in uncoupled channels. Two-nucleon phase shifts as measured, and as given by the Reid soft-core potential, have been used to specify rational functions for the associated S-matrices and which facilitate use of the inversion method. The Reid-potential results serve as a test of the inversion since the potential and its t-marix on- and off-shell are known exactly. That test gives a qualitative insight into the interdependencies between phase shifts, potentials and properties of the two-nucleon t-matrices. Furthermore, it makes credible the two-nucleon t-matrices obtained using measured phase shifts under the same approximations. (orig.)
Two-Nucleon Systems in a Finite Volume
Energy Technology Data Exchange (ETDEWEB)
Briceno, Raul
2014-11-01
I present the formalism and methodology for determining the nucleon-nucleon scattering parameters from the finite volume spectra obtained from lattice quantum chromodynamics calculations. Using the recently derived energy quantization conditions and the experimentally determined scattering parameters, the bound state spectra for finite volume systems with overlap with the 3S1-3D3 channel are predicted for a range of volumes. It is shown that the extractions of the infinite-volume deuteron binding energy and the low-energy scattering parameters, including the S-D mixing angle, are possible from Lattice QCD calculations of two-nucleon systems with boosts of |P| <= 2pi sqrt{3}/L in volumes with spatial extents L satisfying fm <~ L <~ 14 fm.
Path integral formalism for a simple interacting nucleon model
International Nuclear Information System (INIS)
The early onset of the baryon density in QCD simulations can be explained by the high flavour degeneracy when using staggered fermions. A simple interacting nucleon gas model had already shown that the gas condenses at very low chemical potential as in the lattice simulations at four flavours. In order to study more carefully the nucleon gas model in the condensation region we have developed the path integral formalism to treat the first quantization non perturbatively, describing the partition function for the interacting system of nucleons. First Monte Carlo results show good agreement with the lattice QCD simulations for the onset chemical potentials and saturation densities. The extrapolation to nature gives reasonable results. (orig.)
Pion momentum distributions in the nucleon in chiral effective theory
Burkardt, M; Ji, Chueng-Ryong; Melnitchouk, W; Thomas, A W
2012-01-01
We compute the light-cone momentum distributions of pions in the nucleon in chiral effective theory using both pseudovector and pseudoscalar pion-nucleon couplings. For the pseudovector coupling we identify \\delta-function contributions associated with end-point singularities arising from the pion-nucleon rainbow diagrams, as well as from pion tadpole diagrams which are not present in the pseudoscalar model. Gauge invariance is demonstrated, to all orders in the pion mass, with the inclusion of Weinberg-Tomozawa couplings involving operator insertions at the \\pi NN vertex. The results pave the way for phenomenological applications of pion cloud models that are manifestly consistent with the chiral symmetry properties of QCD.
International Nuclear Information System (INIS)
In this contribution, we review the most important physics presented originally in our recent publications. Some new analyses, insights and perspectives are also provided. We showed recently that the symmetry energy Esym (ρ) and its density slope L(ρ) at an arbitrary density ρ can be expressed analytically in terms of the magnitude and momentum dependence of the single-nucleon potentials using the Hugenholtz-Van Hove (HVH) theorem. These relationships provide new insights about the fundamental physics governing the density dependence of nuclear symmetry energy. Using the isospin and momentum (k) dependent MDI interaction as an example, the contribution of different terms in the single-nucleon potential to the Esym (ρ) and L(ρ) are analyzed in detail at different densities. It is shown that the behavior of Esym is mainly determined by the first-order symmetry potential Usym,1(ρ, k) of the single-nucleon potential. The density slope L(ρ) depends not only on the first-order symmetry potential Usym,1(ρ, k) but also on the second-order one Usym,2(ρ, k). Both the Usym,1(ρ, k) and Usym,2(ρ, k) at normal density ρ 0 are constrained by the isospin- and momentum-dependent nucleon optical potential extracted from the available nucleon-nucleus scattering data. The Usym,2(ρ, k) especially at high density and momentum affects significantly the L(ρ), but it is theoretically poorly understood and currently there is almost no experimental constraints known. (orig.)
Excited state systematics in extracting nucleon electromagnetic form factors
Capitani, Stefano; von Hippel, Georg; Jäger, Benjamin; Knippschild, Bastian; Meyer, Harvey B; Rae, Thomas D; Wittig, Hartmut
2012-01-01
We present updated preliminary results for the nucleon electromagnetic form factors for non-perturbatively $\\mathcal{O}(a)$ improved Wilson fermions in $N_f=2$ QCD measured on the CLS ensembles. The use of the summed operator insertion method allows us to suppress the influence of excited states in our measurements. A study of the effect that excited state contaminations have on the $Q^2$ dependence of the extracted nucleon form factors may then be made through comparisons of the summation method to standard plateau fits, as well as to excited state fits.
Structure and Flow of the Nucleon Eigenstates in Lattice QCD
Mahbub, M. Selim; Kamleh, Waseem; Leinweber, Derek B.; Moran, Peter J.; Williams, Anthony G.
2013-01-01
A determination of the excited energy eigenstates of the nucleon, $s=c{1}{2}$, $I={1}{2}$, $N^{\\pm}$, is presented in full QCD using 2+1 flavor PACS-CS gauge configurations. The correlation-matrix method is used and is built using standard nucleon interpolators employing smearings at the fermion sources and sinks. We develop and demonstrate a new technique that allows the eigenvectors obtained to be utilized to track the propagation of the intrinsic nature of energy-states from one quark mass...
Hermes results on 3D imaging of the nucleon
Directory of Open Access Journals (Sweden)
Pappalardo Luciano L.
2016-01-01
Full Text Available The study of the quantum phase-space distribution of quarks and gluons inside nucleons in terms of TMDs and GPDs has become, in the last decade, a cutting-edge research field in hadron physics. These non-perturbative objects, respectively measurable in semi-inclusive deep-inelastic scattering and exclusive processes, allow to obtain 3-dimensional representations of the nucleon in the momentum and spatial coordinates as well as indirect insights into the still unknown parton orbital angular momentum. The HERMES experiment at HERA has been a precursor in this field. A selection of HERMES results sensitive to both TMDs and GPDs is presented.
HERMES Results on the 3D Imaging of the Nucleon
Pappalardo, L. L.
2016-07-01
It the last decades, a formalism of transverse momentum dependent parton distribution functions (TMDs) and of generalised parton distributions (GPDs) has been developed in the context of non-perturbative QCD, opening the way for a tomographic imaging of the nucleon structure. TMDs and GPDs provide complementary three-dimensional descriptions of the nucleon structure in terms of parton densities. They thus contribute, with different approaches, to the understanding of the full phase-space distribution of partons. A selection of HERMES results sensitive to TMDs is presented.
Hermes results on 3D imaging of the nucleon
Pappalardo, Luciano L.
2016-05-01
The study of the quantum phase-space distribution of quarks and gluons inside nucleons in terms of TMDs and GPDs has become, in the last decade, a cutting-edge research field in hadron physics. These non-perturbative objects, respectively measurable in semi-inclusive deep-inelastic scattering and exclusive processes, allow to obtain 3-dimensional representations of the nucleon in the momentum and spatial coordinates as well as indirect insights into the still unknown parton orbital angular momentum. The HERMES experiment at HERA has been a precursor in this field. A selection of HERMES results sensitive to both TMDs and GPDs is presented.
Three-Nucleon Force in the 4He Scattering System
Hofmann, Hartmut M.; Hale, Gerald M.
2002-01-01
We report on a consistent, microscopic calculation of the bound and scattering states in the 4He system employing modern realistic two-nucleon and three-nucleon potentials in the framework of the resonating group model (RGM). We present for comparison with these microscopic RGM calculations the results from a charge-independent, Coulomb-corrected R-matrix analysis of all types of data for reactions in the A=4 system. Comparisons are made for selected examples of phase shifts and measurements ...
O(a) improvement of nucleon matrix elements
International Nuclear Information System (INIS)
We report on preliminary results of a high statistics quenched lattice QCD calculation of nucleon matrix elements within the Symanzik improvement programme. Using the recently determined renormalisation constants from the Alpha Collaboration we present a fully non-perturbative calculation of the forward nucleon axial matrix element with O(a) lattice artifacts completely removed. Runs are made at β=6.0 and β=6.2, in an attempt to check scaling and O(a2) effects. We also briefly describe results for left angle x right angle, the matrix element of a higher derivative operator. (orig.)
Nucleon matrix elements using the variational method in lattice QCD
Dragos, Jack; Kamleh, Waseem; Leinweber, Derek B; Nakamura, Yoshifumi; Rakow, Paul E L; Schierholz, Gerrit; Young, Ross D; Zanotti, James M
2016-01-01
The extraction of hadron matrix elements in lattice QCD using the standard two- and three-point correlator functions demands careful attention to systematic uncertainties. One of the most commonly studied sources of systematic error is contamination from excited states. We apply the variational method to calculate the axial vector current $g_{A}$, the scalar current $g_{S}$ and the quark momentum fraction $\\left$ of the nucleon and we compare the results to the more commonly used summation and two-exponential fit methods. The results demonstrate that the variational approach offers a more efficient and robust method for the determination of nucleon matrix elements.
Generalized Parton Distributions and the Spin Structure of the Nucleon
Ji, X
2002-01-01
Generalized parton distributions are a new type of hadronic observables which has recently stimulated great interest among theorists and experimentalists alike. Introduced to delineate the spin structure of the nucleon, the orbital angular momentum of quarks in particular, the new distributions contain vast information about the internal structure of the nucleon, with the usual electromagnetic form factors and Feynman parton distributions as their special limits. While new perturbative QCD processes, such as deeply virtual Compton scattering and exclusive meson production, have been found to measure the distributions directly in experiments, lattice QCD offers a great promise to provide the first-principle calculations of these interesting observables.
Generalized parton distributions and the spin structure of the nucleon
Ji, Xiangdong
2003-05-01
Generalized parton distributions are a type of hadronic observables which has recently stimulated great interest among theorists and experimentalists alike. Introduced to delineate the spin structure of the nucleon, the orbital angular momentum of quarks in particular, the new distributions contain vast information about the internal structure of the nucleon, with the usual electromagnetic form factors and Feynman parton distributions as their special limits. While new perturbative QCD processes, such as deeply virtual Compton scattering and exclusive meson production, have been found to measure the distributions directly in experiments, lattice QCD offers a great promise to provide the first-principle calculations of these interesting observables.
Generalized parton distributions and the spin structure of the nucleon
International Nuclear Information System (INIS)
Generalized parton distributions are a type of hadronic observables which has recently stimulated great interest among theorists and experimentalists alike. Introduced to delineate the spin structure of the nucleon, the orbital angular momentum of quarks in particular, the new distributions contain vast information about the internal structure of the nucleon, with the usual electromagnetic form factors and Feynman parton distributions as their special limits. While new perturbative QCD processes, such as deeply virtual Compton scattering and exclusive meson production, have been found to measure the distributions directly in experiments, lattice QCD offers a great promise to provide the first-principle calculations of these interesting observables
Scalar strangeness content of the nucleon and baryon sigma terms
Ren, Xiu-Lei; Geng, Li-Sheng; Meng, Jie
2014-01-01
The scalar strangeness content of the nucleon, characterized by the so-called strangeness-nucleon sigma term, is of fundamental importance in understanding its sea-quark flavor structure. We report a determination of the octet baryon sigma terms via the Feynman-Hellmann theorem by analyzing the latest high-statistics $n_f=2+1$ lattice QCD simulations with covariant baryon chiral perturbation theory up to next-to-next-to-next-to-leading order. In particular, we predict $\\sigma_{\\pi N}=55(1)(4)...
Delineating the polarized and unpolarized partonic structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Jimenez-Delgado, Pedro [JLAB
2015-03-01
Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.
Delineating the polarized and unpolarized partonic structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Jimenez-Delgado, Pedro [JLAB
2015-03-01
Our latest results on the extraction of parton distribution functions of the nucleon are reported. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are given, including a careful treatment of hadronic and nuclear corrections, as well as results on the impact of present and future data in our understanding of the spin of the nucleon.
Nucleon strangeness form factors and moments of PDF
Doi, Takumi; Dong, Shao-Jing; Draper, Terrence; Liu, Keh-Fei; Mankame, Devdatta; Mathur, Nilmani; Streuer, Thomas
2010-01-01
The calculation of the nucleon strangeness form factors from N_f=2+1 clover fermion lattice QCD is presented. Disconnected insertions are evaluated using the Z(4) stochastic method, along with unbiased subtractions from the hopping parameter expansion. We find that increasing the number of nucleon sources for each configuration improves the signal significantly. We obtain G_M^s(0) = -0.017(25)(07), which is consistent with experimental values, and has an order of magnitude smaller error. Preliminary results for the strangeness contribution to the second moment of the parton distribution function are also presented.
Hadronic probes of the polarized intrinsic strangeness of the nucleon
International Nuclear Information System (INIS)
We have previously interpreted the various large apparent violations of the naivo Okubo-Zweig-Iizuka (OZI) rule found in many channels in bar pp annihilation at LEAR as evidence for an intrinsic polarized bar ss component of the nucleon wave functions. The model is further supported by new data from LEAR and elsewhere. Here we discuss in more detail the possible form of the bar ss component of the nucleon wave function, interpret the new data and clarify the relative roles of strangeness shake-out and rearrangement, discuss whether alternative interpretations are still allowed by the new data, and propose more tests of the model
The problem of nucleon production in the quark parton model
International Nuclear Information System (INIS)
Quark fragmentation into hadrons, esp. nucleons, is studied fitting empirical fragmentation functions to e+e- annihilation data. We find fragmentation functions deviating from counting rule predictions as well as from scaling due to the threshold in kaon and nucleon production. Using these fragmentation functions we study particle production ratios in ep and large transverse momentum hadronic reactions. In both cases we find the ratios p/π+ and antip/π- to agree roughly in magnitude with the measured ratios. The model is however inconsistent with the transverse momentum-12 behaviour of large transverse momentum proton spectra. (author)
Pion-mass dependence of three-nucleon observables
Hammer, H. -W.; D. R. Phillips; Platter, L.
2007-01-01
We use an effective field theory (EFT) which contains only short-range interactions to study the dependence of a variety of three-nucleon observables on the pion mass. The pion-mass dependence of input quantities in our ``pionless'' EFT is obtained from a recent chiral EFT calculation. To the order we work at, these quantities are the 1S0 scattering length and effective range, the deuteron binding energy, the 3S1 effective range, and the binding energy of one three-nucleon bound state. The ch...
Nucleon form factors, generalized parton distributions and quark angular momentum
International Nuclear Information System (INIS)
We extract the individual contributions from u and d quarks to the Dirac and Pauli form factors of the proton, after a critical examination of the available measurements of electromagnetic nucleon form factors. From this data we determine generalized parton distributions for valence quarks, assuming a particular form for their functional dependence. The result allows us to study various aspects of nucleon structure in the valence region. In particular, we evaluate Ji's sum rule and estimate the total angular momentum carried by valence quarks at the scale μ=2 GeV to be Juv=0.230+0.009-0.024 and Jdv=-0.004+0.010-0.016.
Nucleon axial and tensor charges with dynamical overlap quarks
Yamanaka, N; Hashimoto, S; Kaneko, T
2015-01-01
We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the all-mode-averaging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the all-to-all quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses $m_\\pi$ = 450 and 540 MeV.
Medium effects in the nucleon- nucleus reaction cross-section
International Nuclear Information System (INIS)
The nucleon-nucleus reaction cross-section, σR , has been calculated using Gabblers multiple scattering theory in its optical limit, A medium modified nuclear phase shift function has been obtained for nucleon-nucleus scattering using a medium two body scattering amplitude. In the present calculations, the Coulomb modified Glauber model is used. Also different forms of Gaussian density distribution, for the target nucleus, are used. A comparison of medium modified calculations with the corresponding experimental data has shown that application of the medium effect in the total reaction cross- section plays an important role for low values of energy
Nucleon form factors with Nf=2 dynamical twisted mass fermions
Alexandrou, C; Koutsou, G; Baron, R; Guichon, P; Brinet, M; Carbonell, J; Harraud, P -A; Jansen, K
2009-01-01
We present results on the electromagnetic and axial nucleon form factors using two degenerate flavors of twisted mass fermions on lattices of spatial size 2.1 fm and 2.7 fm and a lattice spacing of about 0.09 fm. We consider pion masses in the range of 260-470 MeV. We chirally extrapolate results on the nucleon axial ch arge, the isovector Dirac and Pauli root mean squared radii and magnetic moment to the physical point and co mpare to experiment.
Quantal Nucleon Diffusion I: Central Collisions of Symmetric Nuclei
Ayik, S; Yilmaz, B; Umar, A S
2016-01-01
Quantal diffusion mechanism of nucleon exchange is studied in the central collisions of several symmetric heavy-ion collisions in the framework of the Stochastic Mean-Field (SMF) approach. Since at bombarding energies below the fusion barrier, di-nuclear structure is maintained, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Quantal diffusion coefficients, including memory effects, for proton and neutron exchanges are extracted microscopically employing the SMF approach. The quantal calculations of neutron and proton variances are compared with the semi-classical results.
Energy Technology Data Exchange (ETDEWEB)
Martens, Frederick H. [Argonne National Laboratory; Jacobson, Norman H.
1968-09-01
This booklet discusses research reactors - reactors designed to provide a source of neutrons and/or gamma radiation for research, or to aid in the investigation of the effects of radiation on any type of material.
Compton scattering and nucleon polarisabilities in chiral EFT: Status and future
Grießhammer, Harald W.; McGovern, Judith A.; Phillips, Daniel R.
2016-05-01
We review theoretical progress and prospects for determining the nucleon's static dipole polarisabilities from Compton scattering on few-nucleon targets, including new values; see Refs. [1-5] for details and a more thorough bibliography.
Separable Kernel of Nucleon-Nucleon Interaction in the Bethe-Salpeter Approach for J=0,1
Bondarenko, S G; Hamamoto, N; Hosaka, Y; Manabe, Y; Toki, H
2003-01-01
The solution for the nucleon-nucleon T matrix in the framework of the covariant Bethe-Salpeter approach for a two spin-one-half particle system with a separable kernel of interaction is analyzed. The explicit analytical connection between parameters of the separable kernel and low energy scattering parameters, deuteron binding energy and phase shifts is established.Covariant separable kernels for positive-energy partial channels with total angular momentum J=0 (1S0+, 3P0+) and J=1 (3S1+-3D1+, 1P1+, 3P1+) are constructed by using obtained relations.
Liu, Jian-Ye; GUO, WEN-JUN; Wang, Shun-Jin; ZUO, WEI; Zhao, Qiang; Yang, Yan-Fang
2001-01-01
Using an isospin-dependent quantum molecular dynamics, nuclear stopping in intermediate heavy ion collisions has been studied. The calculation has been done for colliding systems with different neutron-proton ratios in beam energy ranging from 15MeV/u to 150MeV/u. It is found that, in the energy region from above Fermi energy to 150MeV/u, nuclear stopping is very sensitive to the isospin dependence of in-medium nucleon-nucleon cross section, but insensitive to symmetry potential. From this in...
A search for collective pion production in 2 GeV/Nucleon heavy ion reactions
International Nuclear Information System (INIS)
he π(+-) multiplicity distributions in 12C and 16O induced reactions in nuclear emulsion at 2 GeV/nucleon have been measured. The results are compared to a model in which we assume that only independent nucleon-nucleon scattering occurs. Such a model can explain the complete π(+-) multiplicity spectra, only if we assume a very limited shadow effect, i.e. very few nucleons must be swept out of the nuclei during the time of overlap. (author)
A measurement of the ratio of the nucleon structure function in copper and deuterium
International Nuclear Information System (INIS)
Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function, F2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects. (orig.)
Nucleon form factors for the elastic electron-deuteron scattering at high momentum transfer
Bekzhanov, A V; Burov, V V
2014-01-01
The reaction of the elastic electron-deuteron scattering at high momentum transfer is investigated within the Bethe-Salpeter approach. The relativistic covariant Graz II separable kernel of nucleon-nucleon interactions is used to analyze the deuteron structure functions, form factors and tensor of polarization components. The modern data for the electromagmetic nucleons structure from the double polarization experiments as well as some other models of the nucleon form factors are considered.
International Nuclear Information System (INIS)
This article proposes an overview of research reactors, i.e. nuclear reactors of less than 100 MW. Generally, these reactors are used as neutron generators for basic research in matter sciences and for technological research as a support to power reactors. The author proposes an overview of the general design of research reactors in terms of core size, of number of fissions, of neutron flow, of neutron space distribution. He outlines that this design is a compromise between a compact enough core, a sufficient experiment volume, and high enough power densities without affecting neutron performance or its experimental use. The author evokes the safety framework (same regulations as for power reactors, more constraining measures after Fukushima, international bodies). He presents the main characteristics and operation of the two families which represent almost all research reactors; firstly, heavy water reactors (photos, drawings and figures illustrate different examples); and secondly light water moderated and cooled reactors with a distinction between open core pool reactors like Melusine and Triton, pool reactors with containment, experimental fast breeder reactors (Rapsodie, the Russian BOR 60, the Chinese CEFR). The author describes the main uses of research reactors: basic research, applied and technological research, safety tests, production of radio-isotopes for medicine and industry, analysis of elements present under the form of traces at very low concentrations, non destructive testing, doping of silicon mono-crystalline ingots. The author then discusses the relationship between research reactors and non proliferation, and finally evokes perspectives (decrease of the number of research reactors in the world, the Jules Horowitz project)
Reactor physics and reactor computations
International Nuclear Information System (INIS)
Mathematical methods and computer calculations for nuclear and thermonuclear reactor kinetics, reactor physics, neutron transport theory, core lattice parameters, waste treatment by transmutation, breeding, nuclear and thermonuclear fuels are the main interests of the conference
International Nuclear Information System (INIS)
There are currently 284 research reactors in operation, and 12 under construction around the world. Of the operating reactors, nearly two-thirds are used exclusively for research, and the rest for a variety of purposes, including training, testing, and critical assembly. For more than 50 years, research reactor programs have contributed greatly to the scientific and educational communities. Today, six of the world's research reactors are being shut down, three of which are in the USA. With government budget constraints and the growing proliferation concerns surrounding the use of highly enriched uranium in some of these reactors, the future of nuclear research could be impacted
International Nuclear Information System (INIS)
Object: To provide a jet and missile protective wall of a configuration being inflated toward the center of a reactor container on the inside of a body of the reactor container disposed within a biological shield wall to thereby increase safety of the reactor container. Structure: A jet and missile protective wall comprised of curved surfaces internally formed with a plurality of arch inflations filled with concrete between inner and outer iron plates and shape steel beam is provided between a reactor container surrounded by a biological shield wall and a thermal shield wall surrounding the reactor pressure vessel, and an adiabatic heat insulating material is filled in space therebetween. (Yoshino, Y.)
Bound nucleon dynamics in relativistic mean field theory and quasi-elastic electron scattering
International Nuclear Information System (INIS)
We compare results obtained with relativistic and non-relativistic bound nucleon wave functions on differential cross sections for electron induced one nucleon knock-out at quasi-elastic kinematics. We discuss the role of the negative-energy component of the relativistic bound nucleon wave functions and the issue of factorization of the differential cross section. (authors)
Study of hadron structure in a deep-inelastic scattering of polarized leptons on polarized nucleons
International Nuclear Information System (INIS)
The problem is discussed of nucleon structure research in deep inelastic scattering processes of polarized leptons on polarized nucleons. Using a modified Kuti-Weisskopf model theoretical relations are derived for structure functions involved in the deep inelastic differential cross section of leptons on nucleons. (Z.J.)
Nucleon Structure Function F2 in the Resonance Region and Quark-Hadron Duality
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing; LI Ming-Fei
2003-01-01
Based on a simple nonrelativistic constituent quark model, the nucleon structure function F2 in theresonance region is estimated by taking the contributions from low-lying nucleon resonances into account. Calculatedresults are employed to study quark-hardon duality in the nucleon electron scattering process by comparing them to thescaling behavior from the data in deep inelastic scattering region.
Interacting boson models of nuclear and nucleon structure
Bijker, R.; Leviatan, A.
1998-01-01
Interacting boson models provide an elegant and powerful method to describe collective excitations of complex systems by introducing a set of effective degrees of freedom. We review the interacting boson model of nuclear structure and discuss a recent extension to the nucleon and its excited states.
Nucleon-antinucleon annihilation in chiral soliton model
International Nuclear Information System (INIS)
We investigate annihilation process of nucleons in chiral soliton model by path integral method. Soliton-antisoliton pair is shown to decay into pions at range of order of about 1 fm, defined by SS-bar potential. Contribution of annihilation channel into elastic scattering is discussed. (author). 14 refs, 1 fig
Nucleon Properties from Approximating Chiral Quark Sigma Model
Abu-Shady, M
2009-01-01
We apply the approximating chiral quark model. This chiral quark model is based on an effective Lagrangian which the interactions between quarks via sigma and pions mesons. The field equations have been solved in the mean field approximation for the hedgehog baryon state. Good results are obtained for nucleon properties in comparison with original model.
Fragment Deexcitation of Fission Induced by High Energy Nucleons
Yavshits S.; Grudzevich O.
2010-01-01
The KRIF library of the neutron-, proton- and gamma-spectra emitted by the nuclei excited up to 500 MeV is presented. The KRIF contains information for about 2000 emitters which are the fragments of the ten targets fission induced by the nucleons with the energies up to 3 GeV.
Roy-Steiner-equation analysis of pion-nucleon scattering
Hoferichter, Martin; Ruiz de Elvira, Jacobo; Kubis, Bastian; Meißner, Ulf-G.
2016-04-01
We review the structure of Roy-Steiner equations for pion-nucleon scattering, the solution for the partial waves of the t-channel process ππ → N ¯ N, as well as the high-accuracy extraction of the pion-nucleon S-wave scattering lengths from data on pionic hydrogen and deuterium. We then proceed to construct solutions for the lowest partial waves of the s-channel process πN → πN and demonstrate that accurate solutions can be found if the scattering lengths are imposed as constraints. Detailed error estimates of all input quantities in the solution procedure are performed and explicit parameterizations for the resulting low-energy phase shifts as well as results for subthreshold parameters and higher threshold parameters are presented. Furthermore, we discuss the extraction of the pion-nucleon σ-term via the Cheng-Dashen low-energy theorem, including the role of isospin-breaking corrections, to obtain a precision determination consistent with all constraints from analyticity, unitarity, crossing symmetry, and pionic-atom data. We perform the matching to chiral perturbation theory in the subthreshold region and detail the consequences for the chiral convergence of the threshold parameters and the nucleon mass.
Nuclear masses and the number of valence nucleons
International Nuclear Information System (INIS)
An improved version of the liquid drop model is presented. The addition of two terms, linear and quadratic in the total number of valence nucleons (particles or holes), improves the description of atomic masses, which can be fitted with an r.m.s. error of 1.2 MeV. Predictions are analysed an compared with those of established models
Spin Structure of the Nucleon on the Light Front
International Nuclear Information System (INIS)
We briefly review the spin structure of the nucleon and show that it is best thought in the light-front formulation. We discuss in particular the longitudinal and transverse spin sum rules, the proper definition of canonical orbital angular momentum and the spin–orbit correlation. (author)
Nucleon polarizabilities: From Compton scattering to hydrogen atom
Hagelstein, Franziska; Miskimen, Rory; Pascalutsa, Vladimir
2016-05-01
We review the current state of knowledge of the nucleon polarizabilities and of their role in nucleon Compton scattering and in hydrogen spectrum. We discuss the basic concepts, the recent lattice QCD calculations and advances in chiral effective-field theory. On the experimental side, we review the ongoing programs aimed to measure the nucleon (scalar and spin) polarizabilities via the Compton scattering processes, with real and virtual photons. A great part of the review is devoted to the general constraints based on unitarity, causality, discrete and continuous symmetries, which result in model-independent relations involving nucleon polarizabilities. We (re-)derive a variety of such relations and discuss their empirical value. The proton polarizability effects are presently the major sources of uncertainty in the assessment of the muonic hydrogen Lamb shift and hyperfine structure. Recent calculations of these effects are reviewed here in the context of the "proton-radius puzzle". We conclude with summary plots of the recent results and prospects for the near-future work.
Studying nucleon structure using an Electron-Ion Collider
Burton, Thomas; EIC Team
2011-04-01
The detailed composition of the spin of the nucleon remains unknown. Numerous experiments over the past two decades have shown that the spin of quarks alone cannot account for more than a third of the nucleon's spin. Proton-proton collisions at RHIC suggest a small gluon polarisation, but uncertainties remain large. An Electron-Ion Collider is proposed as future machine for precision studies of nucleon and nuclear structure. It will allow the study of the spin contribution from gluons and quarks, including their flavour decomposition, in heretofore unprecedented precision, and will access a much wider kinematic space than ever before, in particular extending to the currently unmeasured low Bjorken-x sea. The formalism of generalised parton distributions (GPDs), accessible for example via deeply-virtual Compton scattering, promises to allow study of the role of orbital angular momentum in nucleon spin. Furthermore, GPDs will extend understanding of parton distributions beyond the well-known one-dimensional PDFs, accessing three-dimensional structure via the impact parameter distributions of partons.
Nucleon generalized parton distributions from full lattice QCD
International Nuclear Information System (INIS)
We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in Nf=2+1 lattice QCD using domain wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm)3. (orig.)
Photon-Nucleon Collider based on LHC and CLIC
Aksakal, Husnu; Schulte, Daniel; Zimmermann, Frank
2005-01-01
We describe the scheme of a photon-nucleon collider where high energy photons generated by Compton backscattering off a CLIC electron beam, at either 75 GeV or 1.5 TeV are collided with protons or ions stored in LHC. Different design constraints for such a collider are discussed and achievable luminosity performance is estimated.
The nucleon spin decomposition: news and experimental implications
Lorcé, Cédric
2014-01-01
Recently, many nucleon spin decompositions have been proposed in the literature, creating a lot of confusion. This revived in particular old controversies regarding the measurability of theoretically defined quantities. We propose a brief overview of the different decompositions, discuss the sufficient requirements for measurability and stress the experimental implications.
Nucleon-antinucleon annihilation in chiral soliton model
International Nuclear Information System (INIS)
We investigate annihilation process of nucleons in the chiral soliton model by the path integral method. A soliton-antisoliton pair is shown to decay into mesons at range of about 1fm, defined by the S bar S potential. Contribution of the annihilation channel to the elastic scattering is discussed
Fragment Deexcitation of Fission Induced by High Energy Nucleons
Directory of Open Access Journals (Sweden)
Yavshits S.
2010-03-01
Full Text Available The KRIF library of the neutron-, proton- and gamma-spectra emitted by the nuclei excited up to 500 MeV is presented. The KRIF contains information for about 2000 emitters which are the fragments of the ten targets fission induced by the nucleons with the energies up to 3 GeV.
The role of strangeness in the nucleon structure
International Nuclear Information System (INIS)
It is shown that by reformulating an SU(3) Skyrmion model as a random phase approximation (RPA) to an underlying fermion (quark) theory, one can calculate microscopic (quark) properties of the nucleon without explicit account of the quark-gluon degrees of freedom. In particular, the strangeness content of the proton can be estimated with a Skyrmion model that describes well the hyperon spectroscopy
Quantal foundation of the nucleon exchange transport theory
International Nuclear Information System (INIS)
The central elements of the nucleon exchange transport theory are discussed within a fully quantal framework in order to elucidate the principal characteristics, validity and limitations of the theory. Special consideration is given to the mean rate of energy dissipation and the penetrability coefficient. (orig.)
Constraints on nucleon effective mass splitting with heavy ion collisions
International Nuclear Information System (INIS)
A new version of the improved quantum molecular dynamics model has been developed to include standard Skyrme interactions. Four commonly used Skyrme parameter sets, SLy4, SkI2, SkM* and Gs are adopted in the transport model code to calculate the isospin diffusion observables as well as single and double ratios of transverse emitted nucleons. While isospin diffusion observables are sensitive to the symmetry energy term, they are not very sensitive to the nucleon effective mass splitting parameters in the interactions. Our calculations show that the high energy neutrons and protons and their ratios from reactions at different incident energies provide a robust observable to study the momentum dependence of the symmetry potential which leads to the effective mass splitting. However the sensitivity of effective mass splitting effect on the double n/p yield ratios decreases with increasing beam energy, even though high energy protons and neutrons are produced more abundantly at high beam energy. Our calculations show that the optimum incident energy to study nucleon effective masses is between 100–200 MeV per nucleon.
Nucleon to $\\Delta$ and $\\Delta$ form factors in Lattice QCD
Alexandrou, Constantia
2011-01-01
We present recent lattice QCD results on the electroweak nucleon to $\\Delta$ transition and $\\Delta$ form factors using dynamical fermion gauge configurations with a lowest pion mass of about 300 MeV, with special emphasis in the determination of the sub-dominant quadrupole $N\\gamma^*\\rightarrow \\Delta$ and $\\Delta$ electromagnetic form factors.
A relativistic quark–diquark model for the nucleon
Indian Academy of Sciences (India)
Cristian Leonardo Gutierrez; Maurizio De Sanctis
2009-02-01
We developed a constituent quark–diquark model for the nucleon and its resonances using a harmonic oscillator potential for the interaction. The effects due to relativistic kinetic energy correction are studied. Finally, charge form factor of the model is calculated and compared with experimental data.
Hadronization of excited nucleons in nuclear collisions at ISR energies
International Nuclear Information System (INIS)
Calorimeters downstream of the intersection of pα and αα beams in the ISR have been used to study the hadronization of excited nucleons. These data extend and support the conclusions from previous studies of the A-dependence of particle multiplicities in ultrarelativistic p-nucleus collisions, which provided evidence that the proton hadronizes outside the nuclear volume. (orig.)
Exploring Three-Nucleon Forces in Lattice QCD
Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji
2011-01-01
Three-nucleon forces (3NF) are investigated from two-flavor lattice QCD simulations. We utilize the Nambu-Bethe-Salpeter (NBS) wave function to determine two-nucleon forces (2NF) and 3NF in the same framework. As a first exploratory study, we extract 3NF through three nucleons aligned linearly with an equal spacing. This is the simplest geometrical configuration which reduces the huge computational cost of calculating the NBS wave function. Quantum numbers of the three-nucleon system are chosen to be (I, J^P)=(1/2,1/2^+) (the triton channel). Lattice QCD simulations are performed using N_f=2 dynamical clover fermion configurations at the lattice spacing of a = 0.156 fm on a 16^3 x 32 lattice with a large quark mass corresponding to m_\\pi= 1.13 GeV. We find repulsive 3NF at short distance in the triton channel. Several sources of systematic errors are also discussed.
Pion-nucleon scattering around the delta resonance
Long, Bingwei
2009-01-01
We develop a generalized version of heavy-baryon chiral perturbation theory to describe pion-nucleon scattering in a kinematic domain that extends continuously from threshold to the delta-isobar peak. The $P$-wave phase shifts are used to illustrate this framework.
Cluster of nucleons as elementary modes of excitation in nuclei
International Nuclear Information System (INIS)
Conditions which must be fulfilled by clusters of nucleons to qualify as elementary modes of excitation are analysed in terms of single criteria involving experimental binding energies. It is found that the most complex possible mode is the α-like cluster. (orig.)
Photoproduction ofeta-pi pairs off nucleons and deuterons
Kaeser, A; Ahrens, J; Annand, J R M; Arends, H J; Bantawa, K; Bartolome, P A; Beck, R; Braghieri, A; Briscoe, W J; Cherepnya, S; Costanza, S; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Garni, S; Glazier, D I; Hamilton, D; Hornidge, D; Howdle, D; Huber, G M; Jaegle, I; Jude, T C; Kashevarov, V L; Keshelashvili, I; Kondratiev, R; Korolija, M; Krusche, B; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; McGeorge, J C; McNicoll, E; Mekterovic, D; Metag, V; Micanovic, S; Middleton, D G; Mushkarenkov, A; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Otte, P; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S; Robinson, J; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D; Starostin, A; Strub, Th; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Walford, N K; Watts, D P; Werthmueller, D; Witthauer, L
2016-01-01
Quasi-free photoproduction of $\\pi\\eta$-pairs has been investigated from threshold up to incident photon energies of 1.4 GeV, respectively up to photon-nucleon invariant masses up to 1.9 GeV. Total cross sections, angular distributions, invariant-mass distributions of the $\\pi\\eta$ and meson-nucleon pairs, and beam-helicity asymmetries have been measured for the reactions $\\gamma p\\rightarrow p\\pi^0\\eta$, $\\gamma n\\rightarrow n\\pi^0\\eta$, $\\gamma p\\rightarrow n\\pi^+\\eta$, and $\\gamma n\\rightarrow p\\pi^-\\eta$ from nucleons bound inside the deuteron. For the $\\gamma p$ initial state data for free protons have also been analyzed. Finally, the total cross sections for quasi-free production of $\\pi^0\\eta$ pairs from nucleons bound in $^3$He nuclei have been investigated in view of final state interaction (FSI) effects. The experiments were performed at the tagged photon beam facility of the Mainz MAMI accelerator using an almost $4\\pi$ covering electromagnetic calorimeter composed of the Crystal Ball and TAPS dete...
A brief overview of models of nucleon-induced reactions
International Nuclear Information System (INIS)
The basic features of low to intermediate energy nucleon-induced reactions are discussed within the contexts of the optical model, the statistical model, preequilibrium and intranuclear cascade models. The calculation of cross sections and other scattering quantities are described. (author)
Di-hadron fragmentation and mapping of the nucleon structure
Pisano, Silvia
2015-01-01
The fragmentation of a colored parton directly into a pair of colorless hadrons is a non-perturbative mechanism that offers important insights into the nucleon structure. Di-hadron fragmentation functions can be extracted from semi-inclusive electron-positron annihilation data. They also appear in observables describing the semi-inclusive production of two hadrons in deep-inelastic scattering of leptons off nucleons or in hadron-hadron collisions. When a target nucleon is transversely polarized, a specific chiral-odd di-hadron fragmentation function can be used as the analyzer of the net density of transversely polarized quarks in a transversely polarized nucleon, the so-called transversity distribution. The latter can be extracted through suitable single-spin asymmetries in the framework of collinear factorization, thus in a much simpler framework with respect to the traditional one in single-hadron fragmentation. At subleading twist, the same chiral-odd di-hadron fragmentation function provides the cleanest...