WorldWideScience
 
 
1

Nucleon structure functions  

International Nuclear Information System (INIS)

The present status of experimental measurements of the nucleon structure functions is reviewed. The results from nearly all deep inelastic experiments are in good mutual agreement. Principles of the analysis of these structure function data in the framework of QCD are described. The specific features of the perturbative QCD predictions are observed in the data. This provides quantitative tests of the validity of QCD as well as determinations of the various parton distributions in the nucleon and some of the most precise measurements of the strong coupling constant ?s. The future of this field of experimental physics is sketched.

1992-01-01

2

Nucleon structure functions  

International Nuclear Information System (INIS)

[en] In this talk I summarize ideas and plans which have been put forward by members of all collaborations running muon or neutrino experiments at CERN. During our discussions there was general agreement that: i) substantial improvements of structure function measurements in the SPS range are still possible and necessary and ii) it is the responsibility of the present groups and of CERN to provide a ''final'' set of structure functions in the present energy range. (orig.)

1983-02-10

3

Nucleon structure functions  

Energy Technology Data Exchange (ETDEWEB)

New structure function measurements from fixed target experiments and especially HERA are reviewed. The extraction of parton distributions from these measurements is discussed with special emphasis on systematic problems. New information from Drell-Yan and direct photon production experiments are also presented. Finally the present uncertainties of our knowledge of parton distributions are discussed.

Eisele, F. [Heidelberg Univ. (Germany). Physikalishes Institut

1998-12-31

4

Structure function of the nucleon  

Energy Technology Data Exchange (ETDEWEB)

We present a novel method of calculation of the structure function of the 'nucleon' for the two-dimensional MIT bag model which overcomes the defects inherent in previous calculations. In particular we naturally obtain the correct support and normalization. We also find that there is an intrinsic quark-antiquark sea associated with the MIT bag.

Signal, A.I.; Thomas, A.W.

1988-09-08

5

Review on nucleon structure functions  

Energy Technology Data Exchange (ETDEWEB)

The 1994 preliminary data of the HERA experiments H1 and ZEUS on the proton structure function are presented, together with the final data of the muon fixed target experiments E665 at FNAL and NMC at CERN. Perturbative QCD interpretations and extraction of {alpha}{sub s} at low {chi} are discussed. (author). 55 refs.

Feltesse, J.

1995-12-01

6

Nucleon structure functions, resonance form factors, and duality  

International Nuclear Information System (INIS)

A behavior of the nucleon structure functions in resonance region is investigated. Photon- virtuality-dependent expressions are obtained for resonance production from factors, which have correct threshold behavior and take into account the available data on resonance decays. Contributions of resonances to nucleon structure functions are calculated. The obtained expressions are used to investigate the quark-hadron duality in the electron-nucleon scattering processes with the structure function F2 as an example

2003-01-01

7

An experimental review of the nucleon spin structure functions  

CERN Document Server

An experimental review of the nucleon spin structure functions g1 and g2, as measured in deep inelastic scattering of polarized leptons by polarized nucleons, is presented. Particular emphasis is given to the theoretical interpretation of the spin structure functions, to recent experiments at CERN, SLAC and DESY, and to the presentation and discussion of the available experimental data. (20 refs).

Petratos, G G

2001-01-01

8

Structure functions in electron-nucleon deep inelastic scattering  

Energy Technology Data Exchange (ETDEWEB)

The phenomenological expressions for the structure functions in electron-nucleon deep inelastic scattering are proposed and are shown to satisfy the experimental data as well as a number of sum rules.

Saleem, M.; Fazal-E-Aleem (University of the Punjab, Lahore (Pakistan). Dept. of Physics)

1982-06-26

9

Towards a lattice calculation of the nucleon structure functions  

Energy Technology Data Exchange (ETDEWEB)

We have initiated a programme to compute the lower moments of the unpolarised and polarised deep inelastic structure functions of the nucleon in the quenched approxiation. We review our progress to date. (orig.)

Goeckeler, M. [Forschungszentrum Juelich GmbH (Germany). Hoechstleistungsrechenzentrum; Horsley, R. [Forschungszentrum Juelich GmbH (Germany). Hoechstleistungsrechenzentrum]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ilgenfritz, M. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Perlt, H. [Leipzig Univ. (Germany). Fakultaet fuer Physik und Geowissenschaften; Rakow, P. [Freie Univ. Berlin (Germany). Inst. fuer Theoretische Physik; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Forschungszentrum Juelich GmbH (Germany). Hoechstleistungsrechenzentrum; Schiller, A. [Leipzig Univ. (Germany). Fakultaet fuer Physik und Geowissenschaften

1994-12-01

10

Towards a lattice calculation of the nucleon structure functions  

CERN Document Server

We have initiated a programme to compute the lower moments of the unpolarised and polarised deep inelastic structure functions of the nucleon in the quenched approximation. We review our progress to date.

Göckeler, M; Ilgenfritz, E M; Perlt, H; Rakow, P; Schierholz, G; Schiller, A; Goeckeler, M; Horsley, R; Ilgenfritz, M; Perlt, H; Schierholz, G; Schiller, A

1994-01-01

11

Towards a lattice calculation of the nucleon structure functions  

International Nuclear Information System (INIS)

We have initiated a programme to compute the lower moments of the unpolarised and polarised deep inelastic structure functions of the nucleon in the quenched approxiation. We review our progress to date. (orig.)

1994-01-01

12

a Nonextensive Statistical Model for the Nucleon Structure Function  

Science.gov (United States)

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.

Trevisan, Luis Augusto; Mirez, Carlos

2013-07-01

13

Nucleon/nuclei polarized structure function, using Jacobi polynomials expansion  

International Nuclear Information System (INIS)

We use the constituent quark model to extract polarized parton distributions and finally polarized nucleon structure function. Due to limited experimental data which do not cover whole (x, Q2 ) plane and to increase the reliability of the fitting, we employ the Jacobi orthogonal polynomials expansion. It will be possible to extract the polarized structure functions for Helium, using the convolution of the nucleon polarized structure functions with the light cone moment distribution. The results are in good agreement with available experimental data and some theoretical models. (authors)

2010-01-01

14

Experiments on nucleon spin-dependent structure functions  

International Nuclear Information System (INIS)

In this presentation, the earlier measurements of the spin-dependent structure function of the proton in experiments at SLAC and at CERN are reviewed. In addition several new deep inelastic scattering experiments to measure the spin-dependent structure functions of the nucleon, both proton and neutron, will be discussed

1991-01-01

15

Experiments on nucleon spin-dependent structure functions  

Energy Technology Data Exchange (ETDEWEB)

In this presentation, the earlier measurements of the spin-dependent structure function of the proton in experiments at SLAC and at CERN are reviewed. In addition several new deep inelastic scattering experiments to measure the spin-dependent structure functions of the nucleon, both proton and neutron, will be discussed.

Igo, G. (California Univ., Los Angeles, CA (United States). Dept. of Physics); Hughes, V.W. (Yale Univ., New Haven, CT (United States). Dept. of Physics)

1991-01-01

16

Experiments on nucleon spin-dependent structure functions  

Energy Technology Data Exchange (ETDEWEB)

In this presentation, the earlier measurements of the spin-dependent structure function of the proton in experiments at SLAC and at CERN are reviewed. In addition several new deep inelastic scattering experiments to measure the spin-dependent structure functions of the nucleon, both proton and neutron, will be discussed.

Igo, G. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Hughes, V.W. [Yale Univ., New Haven, CT (United States). Dept. of Physics

1991-12-31

17

Experimental study of structure functions of nucleons and nuclei  

International Nuclear Information System (INIS)

[en] The data obtained in experiments of collaboration Bologna-CERN-Dubna-Munic -Sacle (BCDMS) at 120 and 200 GeV and preliminary data at 280 GeV are discussed. The results of structure function measurements in deep inelastic interactions at the above mentioned energies are presented. Experimental data are compared with quantum chromodynamics predictions for structure nucleon function and its moments. The investigation results of quark-parton structure nucleus function are considered as well

1981-01-01

18

Truncated Moment Analysis of Nucleon Structure Functions  

Energy Technology Data Exchange (ETDEWEB)

We employ a novel new approach using "truncated" moments, or integrals of structure functions over restricted regions of x, to study local quark-hadron duality, and the degree to which individual resonance regions are dominated by leading twists. Because truncated moments obey the same Q^2 evolution equations as the leading twist parton distributions, this approach makes possible for the first time a description of resonance region data and the phenomenon of quark-hadron duality directly from QCD.

A. Psaker; W. Melnitchouk; M. E. Christy; C. E. Keppel

2007-11-16

19

Determination of nucleon structure functions from neutrino-iron scattering  

International Nuclear Information System (INIS)

In the present thesis from inelastic neutrino-iron scattering the nucleon structure functions 2xF1, F2, xF3, anti q are determined. The data acquisition was performed 1983 at CERN in the 400 GeV neutrino broad-band beam with the improved CDHS detector. The statistics could be essentially raised against the last CDHS structure-function measurement. (orig./HSI).

1986-01-01

20

Diquark contributions to the nucleon deep inelastic structure functions  

International Nuclear Information System (INIS)

The contributions of diquarks to the nucleon structure functions are discussed in the framework of the parton model and in the most general case of both vector and scalar diquarks inside unpolarized and polarized nucleons. The vector diquark anomalous magnetic moment and the scalar-vector and vector-scalar diquark transitions are also taken into account. The properties of the diquarks and of their form factors, required in order for the resulting scaling violations to be compatible with the observed ones, are discussed. (author)

1990-01-01

 
 
 
 
21

Nuclear effects in F3 structure function of nucleon  

International Nuclear Information System (INIS)

We study nuclear effects in the F3A(x) structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio R(x,Q2)=(F3A(x,Q2))/(AF3N(x,Q2)) and the Gross-Llewellyn Smith (GLS) integral G(x,Q2)=?x1dxF3A(x,Q2) in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.

2008-10-02

22

Nuclear effects in F_3 structure function of nucleon  

CERN Multimedia

We study nuclear effects in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio $R(x,Q^2)=\\frac{F^A_3(x,Q^2)}{AF^N_3(x, Q^2)}$ and the Gross-Llewellyn Smith(GLS) integral $G(x,Q^2)=\\int_x^1 dx F^A_3(x,Q^2)$ in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.

Athar, M Sajjad; Vacas, M J Vicente

2007-01-01

23

A measurement of the ratio of the nucleon structure function in copper and deuterium  

International Nuclear Information System (INIS)

[en] 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.)

1993-01-01

24

Polarized Structure Function of Nucleon and Orbital Angular Momentum  

International Nuclear Information System (INIS)

We have utilized the concept of valon model to calculate the spin structure function of a constituent quark. This structure is universal and arises from perturbative dressing of a valence quark in QCD. With a convolution method the polarized structure functions of proton, neutron, and deuteron are obtained. Our results agree rather well with all available experimental data. It suggests that the sea quark contribution to the spin of nucleon is consistent with zero, in agreement with HERMES data. It also reveals that while the total quark contribution to the spin of a constituent quark, or valon, is almost constant and equal to one, the gluon contribution grows with the increase of Q2, and hence, requiring a sizable negative angular momentum contribution. This component, as well as singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD. We speculate that the gluon contribution to the spin of proton is in the order of 50%. Furthermore, we have determined the polarized valon distribution in a nucleon.

2007-06-13

25

Chiral Quark Soliton Model and Nucleon Spin Structure Functions  

CERN Multimedia

The chiral quark soliton model (CQSM) is one of the most successful models of baryons at quark level, which maximally incorporates the most important feature of low energy QCD, i.e. the chiral symmetry and its spontaneous breakdown. Basically, it is a relativistic mean-field theory with full account of infinitely many Dirac-sea quarks in a rotational-symmetry-breaking mean field of hedgehog shape. The numerical technique established so far enables us to make a nonperturbative evaluation of Casimir effects (i.e. effects of vacuum-polarized Dirac sea) on a variety of baryon observables. This incompatible feature of the model manifests most clearly in its predictions for parton distribution functions of the nucleon. In this talk, after briefly reviewing several basic features of the CQSM, we plan to demonstrate in various ways that this unique model of baryons provides us with an ideal tool for disentangling nonperturbative aspect of the internal partonic structure of the nucleon, especially the underlying spin ...

Wakamatsu, M

2009-01-01

26

QCD, the parton model, and the nucleon polarised structure functions  

CERN Multimedia

The present talk summarises the 1993 situation in understanding the spin structure of the nucleon via electron and muon polarised deep-inelastic scattering (PDIS). The central question I shall address here is if the data can be interpreted as evidence for polarisation in the "strange" nucleon "sea", and I conclude that they can not: incidentally, I also find that they can not be constructed as evidence for violation of perturbative QCD (PQCD), either. Talk presented at "Quinto Convegno su Problemi di Fisica Nucleare Teorica", Cortona (Arezzo, Italy), October 1993. To be published in the proceedings: "Perspectives on Theoretical Nuclear Physics (V)", L. Bracci, et al., eds. (ETS Ed., Pisa 1994)

Gensini, P M

1993-01-01

27

Contribution of Hard Near Threshold Pion Electro Production to Nucleon Structure Functions  

CERN Multimedia

We provide a precise calculation for the contribution of hard near threshold pion electro production to all nucleon structure functions. This framework will allow us to split the required nucleon to pion nucleon transition probability matrix element into an exact threshold part parametrized by nucleon to pion nucleon transition form factors plus soft pion structures. These transition form factors will be related to nucleon form factors by taking into account symmetric and antisymmetric contributions of the needed leading twist nucleon distribution amplitude. Whereas the relations generated by the symmetric contributions are already known, this work will improve these relations by adding reasonable antisymmetric contributions. The obtained results show enhanced and significant consistency to experimental data, so that various predictions for further interesting experiments will be presented.

Sachs, Thorsten

2011-01-01

28

Measurement of the nucleon structure function using high energy muons  

International Nuclear Information System (INIS)

[en] We have measured the inclusive deep inelastic scattering of muons on nucleons in iron using beams of 93 and 215 GeV muons. To perform this measurement, we have built and operated the Multimuon Spectrometer (MMS) in the muon beam at Fermilab. The MMS is a magnetized iron target/spectrometer/calorimeter which provides 5.61 kg/cm2 of target, 9% momentum resolution on scattered muons, and a direct measure of total hadronic energy with resolution sigma/sub nu/ = 1.4?nu(GeV). In the distributed target, the average beam energies at the interaction are 88.0 and 209 GeV. Using the known form of the radiatively-corrected electromagnetic cross section, we extract the structure function F2(x,Q2) with a typical precision of 2% over the range 5 2 2/c2. We compare our measurements to the predictions of lowest order quantum chromodynamics (QCD) and find a best fit value of the QCD scale parameter ?/sub LO/ = 230 +- 40/sup stat/ +- 80/sup syst/ MeV/c, assuming R = 0 and without applying Fermi motion corrections. Comparing the cross sections at the two beam energies, we measure R = -0.06 +- 0.06/sup stat/ +- 0.11/sup syst/. Our measurements show qualitative agreement with QCD, but quantitative comparison is hampered by phenomenological uncertainties. The experimental situation is quite good, with substantial agreement between our measurements and those of others. 86 references

1983-01-01

29

Prescriptions for the scaling variable of the nucleon structure function in nuclei  

International Nuclear Information System (INIS)

We tested several choices of the in-medium value of the Bjorken scaling variable assuming the nucleon structure function in a nucleus to be the same as that of a free nucleon. The results unambiguously show that it is different.

2007-01-01

30

Measurement of the nucleon structure function using high energy muons  

Energy Technology Data Exchange (ETDEWEB)

We have measured the inclusive deep inelastic scattering of muons on nucleons in iron using beams of 93 and 215 GeV muons. To perform this measurement, we have built and operated the Multimuon Spectrometer (MMS) in the muon beam at Fermilab. The MMS is a magnetized iron target/spectrometer/calorimeter which provides 5.61 kg/cm/sup 2/ of target, 9% momentum resolution on scattered muons, and a direct measure of total hadronic energy with resolution sigma/sub nu/ = 1.4..sqrt..nu(GeV). In the distributed target, the average beam energies at the interaction are 88.0 and 209 GeV. Using the known form of the radiatively-corrected electromagnetic cross section, we extract the structure function F/sub 2/(x,Q/sup 2/) with a typical precision of 2% over the range 5 < Q/sup 2/ < 200 GeV/sup 2//c/sup 2/. We compare our measurements to the predictions of lowest order quantum chromodynamics (QCD) and find a best fit value of the QCD scale parameter ..lambda../sub LO/ = 230 +- 40/sup stat/ +- 80/sup syst/ MeV/c, assuming R = 0 and without applying Fermi motion corrections. Comparing the cross sections at the two beam energies, we measure R = -0.06 +- 0.06/sup stat/ +- 0.11/sup syst/. Our measurements show qualitative agreement with QCD, but quantitative comparison is hampered by phenomenological uncertainties. The experimental situation is quite good, with substantial agreement between our measurements and those of others. 86 references.

Meyers, P.D.

1983-12-01

31

Effect of bound nucleon internal structure change on nuclear structure functions  

International Nuclear Information System (INIS)

Effect of bound nucleon internal structure change on nuclear structure functions is investigated based on local quark-hadron duality. The bound nucleon structure functions calculated for charged-lepton and (anti)neutrino scattering are all enhanced in symmetric nuclear matter at large Bjorken-x (x-bar 0.85) relative to those in a free nucleon. This implies that a part of the enhancement observed in the nuclear structure function F2 (in the resonance region) at large Bjorken-x (the EMC effect) is due to the effect of the bound nucleon internal structure change. However, the x dependence for the charged-lepton and (anti)neutrino scattering is different. The former (latter) is enhanced (quenched) in the region 0.8-bar x-bar 0.9 (0.7-bar x-bar 0.85) due to the difference of the contribution from axial vector form factor. Because of these differences charge symmetry breaking in parton distributions will be enhanced in nuclei

2005-04-14

32

Contribution of the spin-1 diquark to the nucleon's g1 structure function  

International Nuclear Information System (INIS)

This is the final installment of a series of work that we have done in the context of the meson cloud model that investigates F2 and g1 structure functions. In our previous work on g1 structure function, we showed that having a spin-0 quark-diquark for the nucleon core along with both pseudoscalar and vector meson clouds was not sufficient to reproduce experimental observation(s) consistently. For the F2 structure function, we found that both superposition of a spin-0 diquark and a spin-1 diquark in the nucleon core along with pseudoscalar and vector meson clouds are needed to reproduce the observed F2(x) and the Gottfried sum rule (GSR) violation. Therefore, in the present work, we consider the contribution of a spin-1 diquark in the nucleon core to the g1 structure function. The calculation is performed in the light-cone frame. The dressed nucleon is assumed to be a superposition of the bare nucleon plus virtual light-cone Fock states of baryon-meson pairs. For the bare nucleon, we consider different quark-diquark configurations along with the possibility that there is no diquark inside the nucleon. The initial distributions are evolved. The final results are compared with experimental results and other theoretical predictions.

2010-01-01

33

Linear estimates of structure functions from deep inelastic lepton-nucleon scattering data. Part 2  

International Nuclear Information System (INIS)

The paper concerns the linear estimation of structure functions from (anti)neutrino-nucleon scattering. The expressions obtained for the structure functions estimate provide correct analysis of their random error and the bias. The bias arises because of the finite number of experimental data and the finite resolution of experiment. 10 refs.

1991-01-01

34

Deep Inelastic Scattering Structure Functions of the Nucleon in Quark Models  

Science.gov (United States)

The connection between the structure functions of a free nucleon measured in deep inelastic scattering (DIS) experiments and the underlying dynamics in the nucleon rest frame in quark models is not well understood. This thesis explores some steps towards improving the theory of nucleon structure functions. The polarized spin structure functions are calculated in the Fermi gas model. The model permits a straightforward calculation in a translationally invariant framework and demonstrates the importance of relativistic kinematics for spin structure functions. The effect of interactions on the leading light-cone singularity of quark fields has been studied in an exactly solvable bound state model. Using the standard paradigm for calculating structure functions in quark models it is found that the leading light-cone singularity differs from that of free field theory. A fully relativistic proton state with good Poincare symmetry is constructed and it is used to study the proton spin structure in DIS experiments. We find that due to internal motion of quarks the u quark occupation number matrix is rotated by a Wigner rotation, and thus the u quark occupation number is not diagonal in the nucleon rest frame. We also observe that the flavor singlet axial charge DeltaSigma (i.e. Delta u + Delta d + Delta s) is not unity even though the implications of quantum chromodynamics (QCD) such as the U(1) axial anomaly are irrelevant in our model.

Wu, Guo-Wei

1995-01-01

35

Soft-gluon corrections to the nucleon structure function F/sub 3/  

Energy Technology Data Exchange (ETDEWEB)

Q/sup 2/ dependence of the nucleon structure function F/sub 3/ is analyzed using an approach inspired by the Bloch-Nordsieck method in the context of quantum chromodynamics. Moments are obtained and compared successfully with the existing data. Detailed comparison with the renormalization group is also made.

Pancheri-Srivastava, G.; Srivastava, Y.N.; Ramon-Medrano, M.

1981-06-01

36

Interpretation of the nucleon structure functions measured in the Gargamelle SPS neutrino/antineutrino experiment  

Energy Technology Data Exchange (ETDEWEB)

The non-singlet part of the nucleon structure functions measured in the Q/sup 2/ range 0.5 to 50 (GeV/c)/sup 2/ is compared to leading and next-to-leading order QCD predictions. The possible contributions of higher twist and target mass effects are also evaluated.

Morfin, J.G.; Weerts, H. (Technische Hochschule Aachen (Germany, F.R.). Lehrstuhl fuer Experimentalphysik 3B und 3. Physikalisches Inst.); Frodesen, A.G. (Bergen Univ. (Norway). Inst. of Physics); Bertrand, D.; Bertrand-Coremans, G.; Dewit, M.; Vilain, P. (Interuniversity Inst. for High Energies, Brussels (Belgium)); Blaes, R.; Escoubes, B.; Petitjean, P. (Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires)

1981-12-31

37

Interpretation of the nucleon structure functions measured in the Gargamelle SPS neutrino/antineutrino experiment  

International Nuclear Information System (INIS)

The non-singlet part of the nucleon structure functions measured in the Q2 range 0.5 to 50 (GeV/c)2 is compared to leading and next-to-leading order QCD predictions. The possible contributions of higher twist and target mass effects are also evaluated. (orig.)

1981-12-31

38

The ratio of the nucleon structure functions Fsup(N)2 for iron and deuterium  

International Nuclear Information System (INIS)

[en] Using the data on deep inelastic muon scattering on iron and deuterium the ratio of the nucleon structure functions F2sup(N)(Fe)/F2sup(N)(D) is presented. The observed x-dependence of this ratio is in disagreement with existing theoretical predictions. (orig.)

1983-03-31

39

Test of determination of nucleon structure functions in the hypothesis of scalar di-quark existence  

International Nuclear Information System (INIS)

[en] The authors present the nucleon structure functions that have been obtained in the hypothesis of existence of a scalar di-quark, progressively broken by increasing energy of electromagnetic probe (Stockolm model). Comparisons with other models and experimental results are presented. 20 figs

1992-01-01

40

Total cross sections and nucleon structure functions in the Gargamelle SPS neutrino/antineutrino experiment  

International Nuclear Information System (INIS)

Total neutrino and antineutrina cross sections in the energy range 15 to 150 GeV, and the nucleon structure functions, F2(x,Q2) and x F3(x,Q2) in the Q2) range 0.5 to 50 (GeV/c)2 habe been measured using a data sample of 3000 neutrino and 3800 antineutrino events. The structure functions show a weak Q2 dependence at different x values. (orig.)

1981-08-27

 
 
 
 
41

Linear estimates of structure functions from deep inelastic lepton-nucleon scattering data. Part 1  

International Nuclear Information System (INIS)

This paper concerns the linear estimation of structure functions from muon(electron)-nucleon scattering. The expressions obtained for the structure functions estimate provide correct analysis of the random error and the bias The bias arises because of the finite number of experimental data and the finite resolution of experiment. The approach suggested may become useful for data handling from experiments at HERA. 9 refs.

1991-01-01

42

Spin structure functions of the nucleon at low Q2 and ?  

International Nuclear Information System (INIS)

[en] Phenomenological approaches to describe the spin structure functions an spin sum rules for proton and neutrons at low momentum transfer Q2 and energy transfer ?, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A1p, A2p and N1n structure functions at CEBAF in a Q2 range from 0.15 to 2.0 GeV2, and a W range from threshold to 2.2 GeV are presented

1993-01-01

43

Spin structure functions of the nucleon at low Q{sup 2} and {nu}  

Energy Technology Data Exchange (ETDEWEB)

Phenomenological approaches to describe the spin structure functions an spin sum rules for proton and neutrons at low momentum transfer Q{sup 2} and energy transfer {nu}, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A{sub 1}{sup p}, A{sub 2}{sup p} and N{sub 1}{sup n} structure functions at CEBAF in a Q{sup 2} range from 0.15 to 2.0 GeV{sup 2}, and a W range from threshold to 2.2 GeV are presented.

Burkert, V.D.

1993-06-30

44

Method on nucleon structure function reconstruction from the deep inelastic scattering data  

International Nuclear Information System (INIS)

To reconstruct the nucleon structure function from the directly measured experimental cross section of the deep inelastic scattering of muons, Fredholm integral equation of the first kind is considered in its two-dimensional version. The free term of the equation (experimental cross section) and the kernel have statistical errors. The quation's solution (structure function) is found by the statistical regularization method, the regularization parameters being chosen on the basis of the maximum likelihood in a laminar enseble of smooth functions. Generalization of the method is suggested, where the kernel errors are taken into account. The use of this a priori information as growth of the structure function in one of the directions is shown.

1983-01-01

45

Investigation of the nucleon structure and the nucleon-nucleon interaction by electron-deuteron scattering  

International Nuclear Information System (INIS)

In this thesis results of measurements of the differential cross sections of the elastic and inelastic electron deuteron scattering are presented. The data were taken at several scattering angles and in the electron energy range of 150 MeV up to 320 MeV. The extracted form factors and structure functions are compared with theoretical results which are sensitive to details of nucleon structure and of the nucleon-nucleon forces. (FKS).

1978-01-01

46

The spin structure of the nucleon  

International Nuclear Information System (INIS)

Based on the results obtained from the inclusive deep inelastic lepton scattering, the spin structure of the nucleon is discussed. The deep inelastic scattering Kinematics is reviewed. The improvement brought by the EMC data to the knowledge of the spin and the strangeness content of the nucleon are summarized. The nucleon's transverse spin structure function and the Burkhardt - Cottingham sum rule are considered. An overview of the quadrupole and double helicity flip structure functions is given.

1990-01-01

47

Determination of nucleon structure functions on the assumption of diquark presence  

International Nuclear Information System (INIS)

[en] In this thesis, we asked for the presence in the nucleons of either scalar or axial vector diquarks. After the introduction of the basis notions on diquarks and their interest in the understanding of various physical problems, we present in the first chapter the theoretical frame in SU(6) symmetry. Chapter 2 and 3 are respectively devoted to the Stockholm and Torino models. We point out to get a very nice fit of the experimental data with models we had to put in a small Q2 dependence in the various quarks distribution functions previously determined. In chapter 4, we used our distribution functions and compared our predictions with experimental results: the ratio of the neutron electromagnetic structure function to that of the proton, the ratio of the longitudinal component to the transverse one for the lepton-nucleon scattering cross-section, so the dileptons production in Drell-Yan process. The conclusion of that study is that the presence of diquarks does not lead, at the moment, to any obvious contradiction with the experimental data; diquarks as constituents are a viable idea, which in certain kinematical regions could be of crucial importance

1992-01-01

48

Analysis of nucleon structure functions in CERN bubble chamber neutrino experiments  

International Nuclear Information System (INIS)

The authors present results for the differential cross sections of neutrinos and antineutrinos on nucleons in the energy range E=2-200 GeV, from the BEBC and Gargamelle experiments. The structure functions F2,2xF1 and xF3 have been evaluated as a function of x and q2. Deviations are observed from Bjorken scaling, which are very similar to those found in electron and muon inelastic scattering. For the Callan-Gross ratio, the authors find 2xF1/F2=0.80+-0.12 and the corresponding value for ==0.15+-0.10. The results are consistent with the Gross-Llewellyn-Smith sum rule; the authors measure >=2.5+-0.5 valence quarks per nucleon. Quark and antiquark distributions are given. The Nachtmann moments of F2 and xF3 are quantitatively consistent with the predictions from QCD. The value of the strong interaction parameter is ?=0.74+-0.05 GeV without corrections, and 0.66+-0.05 GeV including ?2sub(s) corrections. The moments of the gluon distribution are found to be positive and indicate an x distribution of gluons which is comparable with that of the valence quarks. (Auth.)

1978-09-18

49

Nucleon electromagnetic structure revisited  

CERN Multimedia

Unitary and analytic ten-resonance model of the nucleon electromagnetic (e.m.) structure with canonical normalizations and QCD (up to the logarithmic correction) asymptotics is constructed on the four-sheeted Riemann surface, which provides a superposition of vector-meson pole and continuum contributions in a very natural way. As a result it describes simultaneously all existing experimental space-like and time-like data on the proton e.m. form factors (ff's) and on the neutron e.m. ff's as well. A crucial factor in the latter achievement is the inclusion of a contribution of the fourth excited state of the $\\rho(770)$ meson with the parameters $m_{\\rho''''}=2455\\pm53 MeV, \\Gamma_{\\rho''''}=728\\pm2 MeV$ and $(f^{(1)}_{\\rho''''NN}/f_{\\rho''''})=0.0549\\pm0.0005$, $(f^{(2)}_{\\rho''''NN}/f_{\\rho''''})=-0.0103\\pm0.0001$. The pronounced effect of the two-pion continuum on the isovector spectral functions demonstrating a strong enhancement of the left wing of the $\\rho(770)$-resonance close to two-pion threshold, wh...

Dubnicka, S; Weisenpacher, P; Dubnicka, Stanislav; Dubnickova, Anna-Zuzana; Weisenpacher, Peter

2003-01-01

50

Low $x$ double $ln^2(1/x)$ resummation effects at the sum rules for nucleon structure function $g_1$  

CERN Document Server

We have estimated the contributions to the moments of polarized nucleon structure function $g_1(x,Q^2)$ coming from the region of the very low x ($10^{-5}nucleon structure function extrapolated to the region of low $x$ by the means of the double $ln^2(1/x)$ resummation. The $Q^2$ evolution of $g_1$ was described by the unified evolution equations incorporating both the leading order Altarelli-Parisi evolution at large and moderate $x$, and the double $ln^2(1/x)$ resummation at small $x$. The moments were obtained by integrating out the extrapolated nucleon structure function in the region $10^{-5}

Ziaja, B

2001-01-01

51

Nucleon structure using lattice QCD  

Energy Technology Data Exchange (ETDEWEB)

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.

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

52

Nucleon Structure using lattice QCD  

CERN Multimedia

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.

Alexandrou, C; Drach, V; Hatziyiannakou, K; Jansen, K; Kallidonis, C; Koutsou, G; Leontiou, T; Vaquero, A

2013-01-01

53

Structure function measurements in the deep inelastic muon-nucleon scattering  

International Nuclear Information System (INIS)

[en] Measurements of deep inelastic scattering events on a combined copper and deuterium target were performed by the European Muon Collaboration (EMC) using a muon beam at CERN's SPS with energies at 100 GeV and 280 GeV. The data are analysed and compared with a detailed Monte-Carlo simulation and allow the determination of structure functions from both targets. In the light of the present discrepancy between EMC's and BCDMS's structure functions, stringend cuts were applied to the data. The results confirm the EMC structure function measurements on unbound nucleons. The comparison between the copper structure function from this experiment and the NA2 iron structure function shows a trend to lower values at low xBj. (orig.)[de] In der vorliegenden Arbeit wurden die Daten analysiert, die die European Muon Collaboration in ihrem letzten Experiment NA28-Addendum 1985 gemessen hat. Myonen mit einer Nominalenergie von 100 GeV bzw. 280 GeV werden an einem Targetaufbau gestreut, das aus Kupferscheiben und Tanks mit fluessigem Deuterium bestand, die zur gleichen Zeit im Strahl standen. Aus ca. 163.000 tiefinelastischen Streuereignissen wurden absolut normierte Strukturfunktionen des freien und des im Kern eingebundenen Nukleons bestimmt. Die statistischen und die systematischen Fehler betragen bei kleinem xBj in der Regel 2-3%, die Normalisierungsunsicherheit wird mit 5.5% angegeben. Aufgrund der bestehenden Diskrepanzen der Ergebnisse des EMC-NA2- und des BCDMS-Experimentes wurden sehr strenge Anforderungen an die Daten gestellt. Obwohl dies die Statistik deutlich reduzierte, erlaubt die Analyse eindeutige Aussagen ueber die Vergleiche dieser Daten mit anderen Experimenten. (orig.)

1990-01-01

54

One-loop factorization of the nucleon g{sub 2}-structure function in the nonsinglet case  

Energy Technology Data Exchange (ETDEWEB)

We consider the one-loop factorization of the simplest twist-3 process: inclusive deep-inelastic scattering of longitudinally polarized leptons on a transversely polarized nucleon target. By studying the Compton amplitudes for certain quark and gluon states at one loop, we find the coefficient functions for the nonsinglet twist-3 distributions in the factorization formula of g{sub 2}(x{sub B},Q{sup 2}). The result marks the first step towards a next-to-leading order formalism for this transverse-spin-dependent structure function of the nucleon.

Ji, Xiangdong; Lu, Wei; Osborne, Jonathan; Song, Xiaotong

2000-11-01

55

A measurement of differential cross-sections and nucleon structure functions in charged-current neutrino interactions on iron  

Energy Technology Data Exchange (ETDEWEB)

A high-statistics measurement of the differential cross-sections for neutrino-iron scattering in the wide-band neutrino beam at the CERN SPS is presented. Nucleon structure functions are extracted and their Q{sup 2} evolution is compared with the predictions of quantum chromodynamics. (orig.).

Berge, P.; Burkhardt, H.; Dydak, F.; Hagelberg, R.; Krasny, M.W.; Meyer, H.J.; Palazzi, P.; Ranjard, F.; Rothberg, J.; Steinberger, J.; Taureg, H.; Wahl, H.; Williams, R.W.; Wotschack, J. (European Organization for Nuclear Research, Geneva (Switzerland)); Bluemer, H.; Brummel, H.D.; Buchholz, P.; Duda, J.; Eisele, F.; Kampschulte, B.; Kleinknecht, K.; Knobloch, J.; Mueller, E.; Pszola, B.; Renk, B. (Dortmund Univ. (Germany, F.R.). Inst. fuer Physik); Alvarez, T.; Belusevic, R.; Falkenburg, B.; Geiges, R.; Geweniger, C.; Hepp, V.; Keilwerth, H.; Tittel, K. (Heidelberg Univ. (Germany, F.R.). Inst. fuer Hochenergiephysik); Debu, P.; Guyot, C.; Merlo, J.P.; Para, A.; Perez, P.; Perrier, F.; Peyaud, B.; Schuller, J.P.; Turlay, R.; Vallage, B. (CEA Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Physique des Particules Elementaires); Abramowicz, H.; Krolikowski, J.; Lipniacka, A. (Warsaw Univ. (Poland). Inst. Fizyki Doswiadczalnej)

1991-02-01

56

A measurement of differential cross-sections and nucleon structure functions in charged-current neutrino interactions on iron  

International Nuclear Information System (INIS)

A high-statistics measurement of the differential cross-sections for neutrino-iron scattering in the wide-band neutrino beam at the CERN SPS is presented. Nucleon structure functions are extracted and their Q2 evolution is compared with the predictions of quantum chromodynamics. (orig.).

1991-01-01

57

Nucleon isovector structure functions in (2+1)-flavor QCD with domain wall fermions  

CERN Multimedia

We report on numerical lattice QCD calculations of some of the low moments of the nucleon structure functions. The calculations are carried out with gauge configurations generated by the RBC and UKQCD collaborations with (2+1)-flavors of dynamical domain wall fermions and the Iwasaki gauge action ($\\beta = 2.13$). The inverse lattice spacing is $a^{-1} = 1.73$ GeV, and two spatial volumes of ((2.7{\\rm fm})^3) and ((1.8 {\\rm fm})^3) are used. The up and down quark masses are varied so the pion mass lies between 0.33 and 0.67 GeV while the strange mass is about 12 % heavier than the physical one. The structure function moments we present include fully non-perturbatively renormalized iso-vector quark momentum fraction, (_{u-d}), helicity fraction, (_{\\Delta u - \\Delta d}), and transversity, (_{\\delta u - \\delta d}), as well as an unrenormalized twist-3 coefficient, (d_1). The ratio of the momentum to helicity fractions, (_{u-d}/_{\\Delta u - \\Delta d}), does not show dependence on the light quark mass and agrees ...

Aoki, Yasumichi; Lin, Huey-Wen; Ohta, Shigemi; Sasaki, Shoichi; Tweedie, Robert; Yamazaki, Takeshi; Zanotti, James

2010-01-01

58

Nucleon isovector structure functions in (2+1)-flavor QCD with domain wall fermions  

International Nuclear Information System (INIS)

We report on numerical lattice QCD calculations of some of the low moments of the nucleon structure functions. The calculations are carried out with gauge configurations generated by the RBC and UKQCD Collaborations with (2+1)-flavors of dynamical domain-wall fermions and the Iwasaki gauge action (?=2.13). The inverse lattice spacing is a-1=1.73 GeV, and two spatial volumes of (2.7 fm)3 and (1.8 fm)3 are used. The up and down quark masses are varied so the pion mass lies between 0.33 and 0.67 GeV, while the strange mass is about 12% heavier than the physical one. The structure function moments we present include the fully nonperturbatively renormalized isovector quark momentum fraction u-d, the helicity fraction ?u-?d, and transversity ?u-?d, as well as an unrenormalized twist-3 coefficient d1. The ratio of the momentum to helicity fractions, u-d/?u-?d, does not show dependence on the light quark mass and agrees well with the value obtained from experiment. Their respective absolute values, fully renormalized, show interesting trends toward their respective experimental values at the lightest quark mass. A prediction for the transversity, 0.7?u-?d1, though yet to be renormalized, supports the perturbative Wandzura-Wilczek relation.

2010-07-01

59

Feasibility of a high precision measurement of nucleon structure functions at LEP  

International Nuclear Information System (INIS)

Recently, the scaling violation analysis of deep inelastic scattering data has proven to be the most direct and powerful method to test QCD and measure ?MS. The feasibility of a deep inelastic scattering experiment for a high precision measurement of the nucleon structure functions F2 in the Q2 region 2 to 80 GeV2 with the LEP electron beam incident on internal hydrogen and deuterium gas jet targets is investigated. The features which allow a high absolute precision are the precise calibration of the LEP beam energy, a point-like target, a luminosity monitor based on Moeller scattering, instantaneous luminosity higher than 4x1031 cm-2s-1 with 8 LEP bunches and a 50% acceptance which will allow us to reach a luminosity of 1038 cm-2 in a year. Using in parasitic mode the LEP electron beam at the energies of 46 GeV (Z-pole), 80 GeV (W pair production threshold) and 120 GeV (possible future improvement of LEP2000?) the structure functions F-pp and F2n could be measured with a precision of 1% over the x range 0.05 to 0.75. The corresponding precision on ?MS has been estimated at the level of 10 MeV, both statistical and systematic. (author) 20 figs., 4 tabs., 39 refs

1992-01-01

60

Deep inelastic lepton-nucleon interactions and the structure of the nucleon structure functions, multiplicities and nu , nu total cross sections  

CERN Multimedia

Structure functions for nu N and nu N interactions were obtained from the three-quark-boson nucleon model constructed before from the study of deep inelastic eN scattering (see abstr. A54632 of 1971). The results obtained give quantitative relations between eN and nu N, nu N interactions, and explicit expressions for the differential and integral cross sections. With the energy dependence of pion multiplicity for nu N interactions deduced from the experimental data, the calculated total nu N cross sections with no free parameters reproduced both the CERN 1967 propane and the recent Gargamelle results. For nu N interactions, the calculated total cross sections agree also with the Gargamelle data, and a lower pion multiplicity (i.e., about one-half the nu N multiplicity) is predicted. Excluding the effects of intermediate bosons, all have the same 'asymptotic' cross section although the approach to this limit is extremely slow except for sigma /sup nu p/. (27 refs).

Wang, C P

1974-01-01

 
 
 
 
61

Spin-isospin asymmetry in nucleon structure  

International Nuclear Information System (INIS)

[en] The deep-inelastic scattering structure function ratio Fn2/Fp2 and the nucleon spin asymmetries are found to be strongly x-dependent. In the context of the parton model, the observed inhomogeneities mean that quarks with different flavors and spins carry different fractions of the nucleon momentum. We show that all of these asymmetry effects can be qualitatively understood in terms of the admixtures of excited-state configurations in the nucleon wave function due to color hyperfine interactions. ((orig.))

1994-09-19

62

Spin-isospin asymmetry in nucleon structure  

Energy Technology Data Exchange (ETDEWEB)

The deep-inelastic scattering structure function ratio F[sup n][sub 2]/F[sup p][sub 2] and the nucleon spin asymmetries are found to be strongly x-dependent. In the context of the parton model, the observed inhomogeneities mean that quarks with different flavors and spins carry different fractions of the nucleon momentum. We show that all of these asymmetry effects can be qualitatively understood in terms of the admixtures of excited-state configurations in the nucleon wave function due to color hyperfine interactions. ((orig.))

Dziembowski, Z. (Department of Physics, Temple University, Philadelphia, PA 19122 (United States)); Martoff, C.J. (Department of Physics, Temple University, Philadelphia, PA 19122 (United States)); Zyla, P. (Department of Physics, Temple University, Philadelphia, PA 19122 (United States))

1994-09-19

63

Nucleon-nucleon momentum correlation function for light nuclei  

CERN Multimedia

Nucleon-nucleon momentum correlation function have been presented for nuclear reactions with neutron-rich or proton-rich projectiles using a nuclear transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model. The relationship between the binding energy of projectiles and the strength of proton-neutron correlation function at small relative momentum has been explored, while proton-proton correlation function shows its sensitivity to the proton density distribution. Those results show that nucleon-nucleon correlation function is useful to reflect some features of the neutron- or proton-halo nuclei and therefore provide a potential tool for the studies of radioactive beam physics.

Ma, Y G; Chen, J G; Fang, D Q; Guo, W; Liu, G H; Ma, C W; Ma, E J; Shen, W Q; Shi, Y; Su, Q M; Tian, W D; Wang, H W; Wang, K; Wei, Y B; Yan, T Z

2007-01-01

64

Overview of nucleon structure studies  

Energy Technology Data Exchange (ETDEWEB)

A brief overview of the recent activity in the measurement of the elastic electromagnetic proton and neutron form factors is presented. It is discussed how the quality of the data has been greatly improved by performing double polarization experiments, and the role of two-photon exchange processes will be highlighted. The spatial information on the quark charge distribibutions in the nucleon resulting from the form factors measurements will be discussed, as well as the steady rate of improvements made in the lattice QCD calculations. It is discussed how generalized parton distributions have emerged as a unifying theme in hadron physics linking the spatial densities extracted from form factors with the quark momentum distribution information residing in quark structure functions. The recent progress in the electromagnetic excitation of the $\\Delta(1232)$ resonance will also briefly be discussed.

Marc Vanderhaeghen

2007-06-08

65

Experimental study of the nucleon structure functions and of the gluon distribution from charged-current neutrino and antineutrino interactions  

Energy Technology Data Exchange (ETDEWEB)

Inclusive neutrino and antineutrino charged current interactions were studied in the CHARM detector exposed to neutrino and antineutrino Wide Band Beams of the CERN 400 GeV SPS. The x and Q/sup 2/ dependence of the structure functions F/sub 2/ and xF/sub 3/ and of the antiquark momentum distribution q were determined. The data have been interpreted in terms of QCD theory using the Furmanski-Petronzio method. In this way we have determined ..lambda..sub(LO)=(190/sup +70/sub(-40)(stat)+-70 (syst.)) MeV and the structure functions of quarks and gluons without specific assumptions on their analytic dependence. The results agree with previous experiments which relied on model assumptions in the analysis. We conclude that the model independent simultaneous analysis of the xF/sub 3/, F/sub 2/, anti q structure functions gives a more reliable determination of the gluon distribution in the nucleon.

Bergsma, F.; Dorenbosch, J.; Jonker, M.; Nieuwenhuis, C.; Udo, F. (Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands)); Allaby, J.V.; Amaldi, U.; Barbiellini, G.; Barone, L.; Capone, A.

1983-03-31

66

Experimental study of the nucleon structure functions and of the gluon distribution from charged-current neutrino and antineutrino interactions  

International Nuclear Information System (INIS)

Inclusive neutrino and antineutrino charged current interactions were studied in the CHARM detector exposed to neutrino and antineutrino Wide Band Beams of the CERN 400 GeV SPS. The x and Q2 dependence of the structure functions F2 and xF3 and of the antiquark momentum distribution q were determined. The data have been interpreted in terms of QCD theory using the Furmanski-Petronzio method. In this way we have determined #betta#sub(LO)=[190+70sub(-40)(stat)+-70 (syst.)] MeV and the structure functions of quarks and gluons without specific assumptions on their analytic dependence. The results agree with previous experiments which relied on model assumptions in the analysis. We conclude that the model independent simultaneous analysis of the xF3, F2, anti q structure functions gives a more reliable determination of the gluon distribution in the nucleon. (orig.)

1983-03-31

67

Experimental study of the nucleon structure functions and of the gluon distribution from charged-current neutrino and antineutrino interactions  

Science.gov (United States)

Inclusive neutrino and antineutrino charged current interactions were studied in the CHARM detector exposed to neutrino and antineutrino Wide Band Beams of the CERN 400 GeV SPS. The x and Q2 dependence of the structure functions F2 and xF3 and of the antiquark momentum distribution q were determined. The data have been interpreted in terms of QCD theory using the Furmanski-Petronzio method. In this way we have determined ?LO = [190-40+70 (stat) +/- 70 (syst.)] MeV and the structure functions of quarks and gluons without specific assumptions on their analytic dependence. The results agree with previous experiments which relied on model assumptions in the analysis. We conclude that the model independent simultaneous analysis of the xF3, F2, q structure functions gives a more reliable determination of the gluon distribution in the nucleon. Laboratori Nazionali INFN Frascati, Italy.

Bergsma, F.; Dorenbosch, J.; Jonker, M.; Nieuwenhuis, C.; Udo, F.; Allaby, J. V.; Amaldi, U.; Barbiellini, G.; Barone, L.; Capone, A.; Flegel, W.; Metcalf, M.; Panman, J.; Winter, K.; Abt, I.; Aspiazu, J.; Büsser, F. W.; Daumann, H.; Gall, P. D.; Metz, E.; Niebergall, F.; Ranitzsch, K. H.; Stähelin, P.; Gorbunov, P.; Grigoriev, E.; Kaftanov, V.; Khovansky, V.; Rosanov, A.; Baroncelli, A.; Borgia, B.; Bosio, C.; Diemoz, M.; Dore, U.; Ferroni, F.; Longo, E.; Monacelli, P.; de Notaristefani, F.; Pistilli, P.; Santoni, C.; Tortora, L.; Valente, V.

1983-03-01

68

Nucleon Structure from Lattice QCD  

International Nuclear Information System (INIS)

Hadron structure calculations in lattice QCD have seen substantial progress during recent years. We illustrate the achievements that have been made by discussing latest lattice results for a limited number of important observables related to nucleon form factors and generalized parton distributions. A particular focus is placed on the decomposition of the nucleon spin 1/2 in terms of quark spin and orbital angular momentum contributions. Results and limitations of the necessary chiral extrapolations based on ChPT will be briefly discussed.

2011-10-24

69

Spin Structure of the Nucleon  

International Nuclear Information System (INIS)

HERMES is a second generation experiment to study the spin structure of the nucleon, in which measurements of the spin dependent properties of semi-inclusive deep-inelastic lepton scattering are emphasized. The first experimental results from measurements of single-spin asymmetries for pions and kaons in deep-inelastic scattering with transverse target polarization are discussed. Longitudinally polarized beam and target data provide information on the flavor decomposition of the polarized quark distributions in the nucleon and a first glimpse of the gluon polarization. Moreover, first preliminary results for the unpolarized ep ? en? + total cross section are presented and compared to Generalized Parton Distribution calculations

2006-01-01

70

The Weak Structure of the Nucleon  

Directory of Open Access Journals (Sweden)

Full Text Available The weak structure of the nucleon is the non-perturbative response of the nucleon to a weakinteracting probe. Here, I review the existing experimental data at low energy. In particular, the role of fewbody nuclear reactions in constraining the weak response of the nucleon, in vacuum and in nuclear medium, is discussed.

Gazit D.

2010-01-01

71

Nuclear effects on the nucleon structure functions in hadronic high-mass dimuon production  

Energy Technology Data Exchange (ETDEWEB)

We compare the differential cross sections of high-mass muon pair production on deuterium and tungsten by incident negative pions of 140 and 286 GeV. We find an indication of a nuclear effect on the nucleon quark distributions comparable in magnitude to what is observed in muon-iron deep inelastic scattering, whereas the pion-quark distribution is unaffected, compatibly with QCD factorization.

Bordalo, P.; Busson, P.; Kluberg, L.; Romana, A.; Salmeron, R.; Vallee, C.; Blaising, J.J.; Degre, A.; Juillot, P.; Morand, R.

1987-07-16

72

Calculation of functions of a parabolic cylinder in models of dynamic nuclear structure and nucleon-nucleus scattering  

International Nuclear Information System (INIS)

The methods of function calculations of parabolic cylinder and its proper values in a range of real values of argument are developed. A problem of integral calculation is considered, containing the function composition of parabolic cylinder occurred in a theory of nucleon scattering by nonaxial soft nuclei.

1987-01-01

73

Quark-hadron duality and truncated moments of nucleon structure functions  

CERN Multimedia

We employ a novel new approach to study local quark-hadron duality using "truncated" moments, or integrals of structure functions over restricted regions of x, to determine the degree to which individual resonance regions are dominated by leading twist. Because truncated moments obey the same Q^2 evolution equations as the leading twist parton distributions, this approach makes possible for the first time a description of resonance region data and the phenomenon of quark-hadron duality directly from QCD.

Psaker, A; Christy, M E; Keppel, C

2008-01-01

74

Experimental results on polarized structure functions in deep inelastic lepton-nucleon scattering  

International Nuclear Information System (INIS)

A summary is given of experimental results on spin structure functions of the proton g1p(x,Q2), deuteron g1d(x,Q2), and neutron g1n(x,Q2) as measured in deep inelastic scattering of polarized leptons from a polarized target. All results are consistent with the Bjorken sum rule predictions at the Q2 of each experiment. The data do not support the Ellis-Jaffe sum rule prediction for the proton which implies that the hencity carried by the strange quark may be nonzero and that the net quark helicity is smaller than expected from simple quark models

1994-07-01

75

New Measurements of Nucleon Structure Functions from CCFR/NuTeV  

CERN Multimedia

We report on the extraction of the structure functions F_2 and Delta xF_3 = xF_3nu-xF_3nub from CCFR neutrino-Fe and antineutrino-Fe differential cross sections. The extraction is performed in a physics model independent (PMI) way. This first measurement for Delta xF_3, which is useful in testing models of heavy charm production, is higher than current theoretical predictions. Within 5% the F_2 (PMI) values measured in neutrino and muon scattering are in agreement with the predictions of Next-to-Leading-Order PDFs (using massive charm production schemes), thus resolving the long-standing discrepancy between the two measurements.

Bodek, Arie; Adams, T; Alton, A; Arroyo, C G; Avvakumov, S; De Barbaro, L; De Barbaro, P; Bazarko, A O; Bernstein, R H; Bolton, T; Brau, J E; Buchholz, D; Budd, H S; Bugel, L; Conrad, J; Drucker, R B; Fleming, B T; Formaggio, J A; Frey, R; Goldman, J; Goncharov, M; Harris, D A; Johnson, R A; Kim, J H; King, B J; Kinnel, T; Koutsoliotas, S; Lamm, M J; Marsh, W; Mason, D; McFarland, K S

2001-01-01

76

New Measurements of Nucleon Structure Functions from the CCFR/NuTeV Collaboration  

CERN Multimedia

We report on the extraction of the structure functions F_2 and Delta xF_3 = xF_3nu-xF_3nubar from CCFR neutrino-Fe and antineutrino-Fe differential cross sections. The extraction is performed in a physics model independent (PMI) way. This first measurement for Delta xF_3, which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The F_2 (PMI) values measured in neutrino and muon scattering are in good agreement with the predictions of Next to Leading Order PDFs (using massive charm production schemes), thus resolving the long-standing discrepancy between the two sets of data.

Bodek, Arie; Adams, T; Alton, A; Arroyo, C G; Avvakumov, S; De Barbaro, L; De Barbaro, P; Bazarko, A O; Bernstein, R H; Bolton, T; Brau, J E; Buchholz, D; Budd, H S; Bugel, L; Conrad, J; Drucker, R B; Fleming, B T; Formaggio, J A; Frey, R; Goldman, J; Goncharov, M; Harris, D A; Johnson, R A; Kim, J H; King, B J; Kinnel, T; Koutsoliotas, S; Lamm, M J; Marsh, W; Mason, D; McFarland, K S

2000-01-01

77

Measurement of the Nucleon Structure Function F2 in the Nuclear Medium and Evaluation of its Moments  

International Nuclear Information System (INIS)

We report on the measurement of inclusive electron scattering off a carbon target performed with CLAS at Jefferson Laboratory. A combination of three different beam energies 1.161, 2.261 and 4.461 GeV allowed us to reach an invariant mass of the final-state hadronic system W-2.4 GeV with four-momentum transfers Q2 ranging from 0.2 to 5 GeV2. These data, together with previous measurements of the inclusive electron scattering off proton and deuteron, which cover a similar continuous two-dimensional region of Q2 and Bjorken variable x, permit the study of nuclear modifications of the nucleon structure. By using these, as well as other world data, we evaluated the F2 structure function and its moments. Using an OPE-based twist expansion, we studied the Q2-evolution of the moments, obtaining a separation of the leading-twist and the total higher-twist terms. The carbon-to-deuteron ratio of the leading-twist contributions to the F2 moments exhibits the well known EMC effect, compatible with that discovered previously in x-space. The total higher-twist term in the carbon nucleus appears, although with large systematic uncertainites, to be smaller with respect to the deuteron case for n

2010-11-01

78

New Results on Nucleon Spin Structure  

Energy Technology Data Exchange (ETDEWEB)

Recent precision spin structure data from Jefferson Lab have significantly advanced our knowledge of nucleon structure in the valence quark (high-x) region and improved our understanding of higher-twist effects, spin sum rules and quark-hadron duality. First, results of a precision measurement of the neutron spin asymmetry, A{sub 1}{sup n}, in the high-x region are discussed. The new data shows clearly, for the first time, that A{sub 1}{sup n} becomes positive at high x. They provide crucial input for the global fits to world data to extract polarized parton distribution functions. Preliminary results on A{sub 1}{sup p} and A{sub 1}{sup d} in the high-x region have also become available. The up and down quark spin distributions in the nucleon were extracted. The results for {Delta}d/d disagree with the leading-order pQCD prediction assuming hadron helicity conservation. Then, results of a precision measurement of the g{sub 2}{sup n} structure function to study higher-twist effects are presented. The data show a clear deviation from the lead-twist contribution, indicating a significant higher-twist (twist-3 or higher) effect. The second moment of the spin structure functions and the twist-3 matrix element d{sub 2}{sup n} results were extracted at a high Q{sup 2} of 5 GeV{sup 2} from the measured A{sub 2}{sup n} in the high-x region in combination with existing world data and compared with a Lattice QCD calculation. Results for d{sub 2}{sup n} at low-to-intermediate Q{sup 2} from 0.1 to 0.9 GeV{sup 2} were also extracted from the JLab data. In the same Q{sup 2} range, the Q{sup 2} dependence of the moments of the nucleon spin structure functions was measured, providing a unique bridge linking the quark-gluon picture of the nucleon and the coherent hadronic picture. Sum rules and generalized forward spin polarizabilities were extracted and compared with Chiral Perturbation Theory calculations and phenomenological models. Finally, preliminary results on the resonance spin structure functions in the Q{sup 2} range from 1 to 4 GeV{sup 2} were presented, which, in combination with DIS data, will enable a detailed study of the quark-hadron duality in spin structure functions.

Jian-Ping Chen

2005-09-10

79

The Spin Structure of the Nucleon  

CERN Multimedia

This article reviews our present understanding of QCD spin physics: the proton spin puzzle and new developments aimed at understanding the transverse structure of the nucleon. We discuss present experimental investigations of the nucleon's internal spin structure, the theoretical interpretation of the different measurements and the open questions and challenges for future investigation.

Aidala, Christine A; Hasch, Delia; Mallot, Gerhard K

2012-01-01

80

Nucleon structure in a relativistic quark model  

International Nuclear Information System (INIS)

We study nucleon structure in the relativistic quark model based on the Bakamjian-Thomas construction of the Poincare generators for an arbitrary quantization surface. The one body, single particle approximation to the current operators is used to calculate electromagnetic matrix elements. The Lorentz symmetry breaking resulting from such an approximation is fully investigated. The results for the light front and instant quantization limits are detailed. A suggestion for the resolution of the quark model inability to simultaneously describe the positive neutron electric form factor, GnE(Q2) at small Q2 and the negative slope of the neutron to proton structure function ratio at large x is presented

1995-01-01

 
 
 
 
81

Nucleon structure in a relativistic quark model  

Science.gov (United States)

We study nucleon structure in the relativistic quark model based on the Bakamjian-Thomas construction of the Poincaré generators for an arbitrary quantization surface. The one body, single particle approximation to the current operators is used to calculate electromagnetic matrix elements. The Lorentz symmetry breaking resulting from such an approximation is fully investigated. The results for the light front and instant quantization limits are detailed. A suggestion for the resolution of the quark model inability to simultaneously describe the positive neutron electric form factor, GnE(Q2) at small Q2 and the negative slope of the neutron to proton structure function ratio at large x is presented.

Szczepaniak, Adam; Ji, Chueng-Ryong; Cotanch, Stephen R.

1995-11-01

82

Polarized Structure Function $\\sigma_{LT'}$ for $p({\\vec e},e'K^+)\\Lambda$ in the Nucleon Resonance Region  

CERN Multimedia

The first measurements of the polarized structure function $\\sigma_{LT'}$ for the reaction $p(\\vec e,e'K^+)\\Lambda$ in the nucleon resonance region are reported. Measurements are included from threshold up to $W$=2.05 GeV for central values of $Q^2$ of 0.65 and 1.00 GeV$^2$, and nearly the entire kaon center-of-mass angular range. $\\sigma_{LT'}$ is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate s-channel resonances, as well as resonant and non-resonant processes. The results for $\\sigma_{LT'}$ are comparable in magnitude to previously reported results from CLAS for $\\sigma_{LT}$, the real part of the same response. An intriguing sign change in $\\sigma_{LT'}$ is observed in the high $Q^2$ data at $W\\approx 1.9$ GeV. Comparisons to several existing model predictions are shown.

Nasseripour, R; Ambrozewicz, P; Carman, D S; Amaryan, M J; Anciant, E; Anghinolfi, M; Asavapibhop, B; Asryan, G; Audit, G; Auger, T; Avakian, H; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Battaglieri, M; Beard, K; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Blaszczyk, L; Bonner, B E; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Casey, L; Cetina, C; Chen, S; Cheng, L; Cole, P L; Collins, P; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Credé, V; Dale, D; Dashyan, N; De Masi, R; De Vita, R; De Sanctis, E; Degtyarenko, P V; Dennis, L; Deur, A; Dhuga, K S; Dickson, R; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fatemi, R; Fedotov, G; Feldman, G; Feuerbach, R J; Forest, T A; Fradi, A; Funsten, H; Garçon, M; Gavalian, G; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girard, P; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hafidi, K; Hakobyan, H; Hanretty, C; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hu, J; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Jo, H S; Johnstone, J R; Joo, K; Jüngst, H G; Kalantarians, N; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Kossov, M; Krahn, Z; Kramer, L H; Kubarovski, V; Kühn, J; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Livingston, K; Lu, H Y; Lukashin, K; MacCormick, M; Manak, J J; Markov, N; Mattione, P; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Moreno, B; Moriya, K; Morrow, S A; Moteabbed, M; Müller, J; Munevar, E; Mutchler, G S; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Niyazov, R A; Nozar, M; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Anefalos Pereira, S; Peterson, G; Philips, S A; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Pozdniakov, S; Preedom, B M; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Qin, L M; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Rosner, G; Rossi, P; Rubin, P D; Sabati, F; Salamanca, J; Salgado, C; Santoro, J P; Sapunenko, V; Sayre, D; Schumacher, R A; Serov, V S; Shafi, A; Sharabyan, Yu G; Sharov, D; Shvedunov, N V; Simionatto, S; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Sokhan, D; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Tkabladze, A; Tkachenko, S; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Watts, D P; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J; Zhao, B; Zhao, Z W

2008-01-01

83

Determination of the nucleon structure functions in the study of the inclusive charged current interactions of neutrinos and antineutrinos in iron between 30 and 200 GeV  

International Nuclear Information System (INIS)

In the deep inelastic neutrino scattering experiment of the CERN-Dortmund-Heidelberg-Saclay collaboration realized on the CERN SPS narrow band beam, we have measured 23000 charged current neutrino and 6200 antineutrino interactions. The structure functions of the nucleon have been extracted from the differential cross sections on iron and compared with parton model predictions. The total cross sections and the fraction of momentum carried by the antiquarks in the nucleon have been measured as function of the neutrino energy. The structure functions obtained for different Q2 bins show significant deviations from scale invariance. The data are in agreement with QCD predictions for a value of the scale parameter ? between 300 and 700 MeV

1980-01-01

84

About nucleon-nucleon potential: meson exchange currents and relativistic approach of nuclear structure  

International Nuclear Information System (INIS)

[en] 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

1986-01-01

85

Evolution of nucleon structure functions in the Q2 range between 20 and 10 000 GeV2 from a new QCD analysis of neutrino data  

International Nuclear Information System (INIS)

From the nucleon structure functions measured by the CHARM Collaboration in inclusive neutrino and antineutrino CC interactions we determined the QCD parameter ?sub(MS) = 310 +- 140 (stat.) +- 70 (syst.) MeV using the Furmanski-Petronzio method. With the same method we extrapolated the behaviour of the quark (q + q) and the gluon x-distributions up to Q2 = 10000 GeV2 using perturbative QCD. The extrapolated structure functions are compared with recent results coming from the two-jet differential cross section in proton-antiproton interactions at ?s = 540 GeV and Q2 = 2000 GeV2. (orig.)

1985-03-21

86

Evolution of nucleon structure functions in the QS range between 20 and 10 000 GeVS from a new QCD analysis of neutrino data  

Energy Technology Data Exchange (ETDEWEB)

From the nucleon structure functions measured by the CHARM Collaboration in inclusive neutrino and antineutrino CC interactions we determined the QCD parameter sub(MS) = 310 +- 140 (stat.) +- 70 (syst.) MeV using the Furmanski-Petronzio method. With the same method we extrapolated the behaviour of the quark (q + q) and the gluon x-distributions up to QS = 10000 GeVS using perturbative QCD. The extrapolated structure functions are compared with recent results coming from the two-jet differential cross section in proton-antiproton interactions at s = 540 GeV and QS = 2000 GeVS. (orig.).

Bergsma, F.; Dorenbosch, J.; Allaby, J.V.; Amaldi, U.; Barbiellini, G.; Flegel, W.; Lanceri, L.; Metcalf, M.; Nieuwenhuis, C.; Panman, J.

1985-03-21

87

Evolution of nucleon structure functions in the Q2 range between 20 and 10 000 GeV2 from a new QCD analysis of neutrino data  

Science.gov (United States)

From the nucleon structure functions measured by the CHARM Collaboration in inclusive neutrino and antineutrino CC interactions we determined the QCD parameters ?MS = 310 +/- 140 (stat.) +/- 70(syst.) MeV using the Furmanski- Petronzio method. With the same method we extrapolated the behaviour of the quark (q + q) and the gluon x-distributions up to Q2 = 10 000 GeV2 using perturbative QCD. The extrapolated structure functions are compared with recent results coming from the two-jet differential cross section in proton-antiproton interactions at ?s = 540 GeV and Q2 = 2000 GeV2. Laboratori Nazionali INFN Frascati, Frascati, Italy.

Bergsma, F.; Dorenbosch, J.; Allaby, J. V.; Amaldi, U.; Barbiellini, G.; Flegel, W.; Lanceri, L.; Metcalf, M.; Nieuwenhuis, C.; Panman, J.; Santoni, C.; Winter, K.; Abt, I.; Aspiazu, J.; Büsser, F. W.; Daumann, H.; Gall, P. D.; Hebbeker, T.; Niebergall, F.; Schütt, P.; Stähelin, P.; Gorbunov, P.; Grigoriev, E.; Khovansky, V.; Rosanov, A.; Baroncelli, A.; Barone, L.; Borgia, B.; Bosio, C.; Capone, A.; Diemoz, M.; Dore, U.; Ferroni, F.; Longo, E.; Luminari, L.; Monacelli, P.; de Notaristefani, F.; Tortora, L.; Valente, V.

1985-03-01

88

Nucleon spin structure functions  

International Nuclear Information System (INIS)

[en] There has been recent excitement arising from the claim by the EMC collaboration that none of the proton's spin is carried by quarks. There are many textbooks, including those written by some members of this audience which assert that the proton's spin is carried by quarks. I will review the history of deep inelastic scattering of polarized leptons from polarized protons, culminating in this most recent dramatic claim. I will show that, for the last decade, data have appeared consistent with predictions of the quark model and highlight what the new and potentially exciting data are. I will conclude with suggestions for the future, and discuss the polarization dependence of inclusive hadron production. 35 refs

1989-02-03

89

Insight into nucleon structure from generalized parton distributions  

CERN Multimedia

The lowest three moments of generalized parton distributions are calculated in full QCD and provide new insight into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon.

Negele, J W; Dreher, P; Edwards, R; Fleming, G; Hagler, P; Lippert, T; Pochinsky, A V; Renner, D B; Richards, D; Schilling, K; Schroers, W; Hagler, Ph.; Lippert, Th.

2003-01-01

90

Nucleon structure in a relativistic quark model  

Energy Technology Data Exchange (ETDEWEB)

We study nucleon structure in the relativistic quark model based on the Bakamjian-Thomas construction of the Poincare generators for an arbitrary quantization surface. The one body, single particle approximation to the current operators is used to calculate electromagnetic matrix elements. The Lorentz symmetry breaking resulting from such an approximation is fully investigated. The results for the light front and instant quantization limits are detailed. A suggestion for the resolution of the quark model inability to simultaneously describe the positive neutron electric form factor, {ital G}{sup {ital n}}{sub {ital E}}({ital Q}{sup 2}) at small {ital Q}{sup 2} and the negative slope of the neutron to proton structure function ratio at large {ital x} is presented.

Szczepaniak, A.; Ji, C.; Cotanch, S.R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

1995-11-01

91

Model of the soft structure of nucleons  

International Nuclear Information System (INIS)

[en] The possibility of extending the Feynman quark-parton model to the region of small momentum transfers is considered. Expressions for elastic form factors and structure functions are obtained. The behavior of the Sachs form factor is shown to obey the dipole formula. The nucleon magnetic moment is expressed in terms of the minimum value xmin of the momentum fraction carried by a constituent. The value of xmin corresponds to the effective constituent mass m=0.27 GeV. In this model, the violation of the Callan-Gross ratio is associated with the dynamics of soft processes. A calculation scheme of hadronization is proposed and elaborated to describe proton dissociation in soft ep scattering. The scheme does not require knowledge of the fragmentation function. 14 refs., 11 figs

1995-01-01

92

Model of the soft structure of nucleons  

Energy Technology Data Exchange (ETDEWEB)

The possibility of extending the Feynman quark-parton model to the region of small momentum transfers is considered. Expressions for elastic form factors and structure functions are obtained. The behavior of the Sachs form factor is shown to obey the dipole formula. The nucleon magnetic moment is expressed in terms of the minimum value x{sub min} of the momentum fraction carried by a constituent. The value of x{sub min} corresponds to the effective constituent mass m=0.27 GeV. In this model, the violation of the Callan-Gross ratio is associated with the dynamics of soft processes. A calculation scheme of hadronization is proposed and elaborated to describe proton dissociation in soft ep scattering. The scheme does not require knowledge of the fragmentation function. 14 refs., 11 figs.

Dement`ev, R.K.; Zaramenskii, M.I.; Leikin, E.M.; Novokshanov, N.P. [Moscow State Univ. (Russian Federation)

1995-06-01

93

Test of QCD and a measurement of ? from scaling violations in the nucleon structure function F2(x,Q2) at high Q2  

International Nuclear Information System (INIS)

Scaling violations in the nucleon structure function F2(x, Q2) measured with high statistics in deep inelastic scattering of muons on a carbon target are compared to predictions of perturbative QCD. Excellent agreement is observed with numerical solutions of the Altarelli-Parisi evolution equations over entire x and Q2 range of the data. In a next-to-leading order nonsinglet approximation, the QCD mass scale parameter ?MS is determined to be 230 ± 20 (stat.) ± 60 (syst.) MeV. A singlet fit to the data favours a soft gluon distribution

1987-01-01

94

Probing nuclear structure with nucleons; Sonder la structure nucleaire avec des nucleons  

Energy Technology Data Exchange (ETDEWEB)

The goal of this lecture is to show how nucleon scattering can be used to probe the structure of target nuclei, and how nucleon scattering observables can be interpreted in terms of nuclear structure using microscopic optical potentials. After a brief overview of the specificities of nucleon-nucleus scattering, and a quick reminder on scattering theory, the main part of this lecture is devoted to the construction of optical potentials in which the target nuclei structure information is folded with an effective interaction. Several examples of such microscopic optical model potentials are given. (author)

Bauge, E. [CEA Bruyeres-le-Chatel, Service de Physique Nucl aire, 91 (France)

2007-07-01

95

Nucleon structure study by virtual Compton scattering  

International Nuclear Information System (INIS)

[en] It is proposed to study nucleon structure by virtual Compton scattering using the Hall A HRS spectrometers. This reaction is planned to be measured in the Roper resonance region and at the highest center of mass energy to observe the beginning of the hard scattering regime. (author) 25 refs.; 8 figs.; 6 tabs

1993-01-01

96

Quark-spin structure of the nucleon: 20 years of the JINR-CERN collaboration  

International Nuclear Information System (INIS)

[en] Problem on quark-spin structure of nucleon is discussed. Review of the 20-year cooperation between the JINR and CERN in the area of deep inelastic muon-nucleon scattering is presented. Main attention was paid to precision measurements of scale invariance violations and to nucleon internal spin structure. Cross sections of deep inelastic scattering and structural functions in a quark-parton model are determined. 84 refs., 17 figs., 3 tabs

1996-01-01

97

Structure functions and structure function ratio F2n/F2p at small xBj and Q2 in muon-nucleon scattering  

International Nuclear Information System (INIS)

[en] Preliminary results on the measurement of the structure functions F2p(xBj, Q2) and F2d(xBj, Q2) and of the ratio F2n/F2p from experiment E665 are presented. The data were obtained using 465 GeV/c muons scattering off liquid hydrogen and deuterium targets. The dependence of the structure functions on xBj and Q2 is examined in the kinematic range xBj > 8 x 10-4 and Q2 > 0.2 GeV2/c2. The structure function ratio is presented as a function of xBj, for xBj > 10-6

1994-06-06

98

Nucleon Structure and Generalized Parton Distributions  

Energy Technology Data Exchange (ETDEWEB)

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.

Eric Voutier

2006-06-28

99

Parity violation in the nucleon wave function  

Energy Technology Data Exchange (ETDEWEB)

In a recent letter, Nardulli et al. have derived a low energy potential representing the parity violating nucleon-nucleon interaction induced by parity non-conservation in the nucleon wavefunction. It point out that this potential is in conflict with the data on parity non-conservation in s-d shell nuclei.

McKellar, B.H.J.

1984-04-12

100

Elastic scattering via quark structure of nucleons  

International Nuclear Information System (INIS)

In the framework of the Glauber multiple-scattering theory, the elastic collisions of proton-proton (pp) at the center-of-mass energies ?(s)=23.5, 30.7, 44.7, and 52.8 GeV and alpha-proton (?p) at ?(s)=88 and 89 GeV are analyzed by considering the quark structure of their constituents. The differential cross-section containing the full multiple-scattering series between their quarks is calculated using Gaussian forms for the quark density and quark-quark (QQ) scattering amplitudes. The results obtained from the quark model and the conventional nucleon model are compared with the experimental data. The comparison shows that the nucleon model reproduces the experimental data more satisfactorily than the quark model, and both approaches have limited success in describing the data at such energies. The agreement with the experimental data is improved by the inclusion of the phase variation. (orig.)

2005-01-01

 
 
 
 
101

Measurement of differential neutrino-nucleon cross-sections and structure functions using the CHORUS lead calorimeter  

CERN Document Server

A high-statistics sample of neutrino and anti-neutrino interactions in a lead target has been recorded in the 1998 CHORUS run at CERN. Preliminary measurements of differential nu N cross-sections and of the structure functions F/sub 2/(x, Q/sup 2/), xF/sub 3/(x, Q/sup 2/) and R(x, Q/sup 2/) are presented.

Oldeman, R G C

2001-01-01

102

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.

1993-01-01

103

Electromagnetic studies of nucleon and nuclear structure  

Energy Technology Data Exchange (ETDEWEB)

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 {sup 12}C and {sup 16}O are reported, as well as work on nuclear structure models and instrumentation development.

Heisenberg, J.H.; Calarco, J.R.; Hersman, F.W.; Dawson, J.F.

1993-06-01

104

Internal Spin Structure of the Nucleon in Polarized Deep Inelastic Muon-Nucleon Scattering  

International Nuclear Information System (INIS)

We present the study of the internal spin structure of the nucleon in spin-dependent deep inelastic scattering of muons on nucleons. The data were taken by the NA47 experiment of the Spin Muon Collaboration (SMC) on the high energy muon beam at CERN. The experiment used the polarized proton and deuteron targets. The structure function g1p(x) and g1d(x) were determined from the asymmetries of the spin-dependent event rates in the range of 0.0032>=10 GeV2. Using the first moments of these structure functions an agreement with the Bjorken sum rule prediction was found within one standard deviation. The first moments of g1(x), for both proton and deuteron, are smaller than the Ellis-Jaffe sum rule prediction. This disagreement can be interpreted in terms of negative polarization of the strange sea in the nucleon. The singlet part of the axial current matrix element can be interpreted as an overall spin carried by quarks in the nucleon. Its value is significantly smaller than nucleon spin. Semi-inclusive asymmetries of yields of positive and negative hadrons produced on both targets were also measured and analysed in term of quark-parton model, together with inclusive asymmetries. From this analysis the quark spin distributions were determined, separately for valence u and d quarks and for non-strange sea quarks. Valence u quarks are positively polarized and their polarization increases with x. Valence d quarks are negatively polarized and their polarization does not exhibit any x-dependence. The non-strange sea is unpolarized in the whole measured range of x. The first moments of the valance quark spin distributions were found consistent with the values obtained from weak decay constants F and D and their second moments are consistent with lattice QCD calculations. In the QCD analysis of the world data the first moment of the gluon spin distribution was found with a large error. Also, a search for a non-perturbative anomaly at high x was done on the world data and the result was consistent with null. An extensive discussion of the SMC results and a comparison with results of SLAC experiment is presented. The new experiment of the COMPASS Collaboration, approved and being currently in preparation at CERN, was presented. The main physics issues of the muon part of this experiment, which are the gluon polarization and a continuation of the physics program of the SMC, were discussed. (author)

1998-01-01

105

Double logarithms, $ln^2(1/x)$, and the NLO DGLAP evolution for the non-singlet component of the nucleon spin structure function, $g_1$  

CERN Multimedia

Theoretical predictions show that at low values of Bjorken $x$ the spin structure function is influenced by large logarithmic corrections, $ln^2(1/x)$, which may be predominant in this region. These corrections are also partially contained in the NLO part of the standard DGLAP evolution. Here we calculate the non-singlet component of the nucleon structure function, $g_1^{NS}=g_1^p-g_1^n$, and its first moment, using a unified evolution equation. This equation incorporates the terms describing the NLO DGLAP evolution and the terms which contribute to the $ln^2(1/x)$ resummation. In order to avoid double counting in the overlapping regions of the phase-space, a unique way of including the NLO terms into the unified evolution equation is proposed. The scheme-independent results obtained from this unified evolution are compared to the NLO fit to experimental data, GRSV'2000. Analysis of the first moments of $g_1^{NS}$ confirms that the unified evolution including the $ln^2(1/x)$ resummation goes beyond the NLO DG...

Ziaja, B

2002-01-01

106

Nucleon structure study by virtual compton scattering  

International Nuclear Information System (INIS)

We propose to study nucleon structure by Virtual Compton Scattering using the reaction p(e,e'p)? with the MAMI facility. We will detect the scattered electron and the recoil proton in coincidence in the high resolution spectrometers of the hall A1. Compton events will be separated from the other channels (principally ?0 production) by missing-mass reconstruction. We plan to investigate this reaction near threshold. Our goal is to measure new electromagnetic observables which generalize the usual magnetic and electric polarizabilities. (authors). 9 refs., 18 figs., 7 tabs.

1995-01-01

107

Nucleon structure and properties of dense matter  

International Nuclear Information System (INIS)

[en] 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)

1988-01-01

108

Nucleon structure study by virtual compton scattering  

Energy Technology Data Exchange (ETDEWEB)

We propose to study nucleon structure by Virtual Compton Scattering using the reaction p(e,e`p){gamma} with the MAMI facility. We will detect the scattered electron and the recoil proton in coincidence in the high resolution spectrometers of the hall A1. Compton events will be separated from the other channels (principally {pi}{sup 0} production) by missing-mass reconstruction. We plan to investigate this reaction near threshold. Our goal is to measure new electromagnetic observables which generalize the usual magnetic and electric polarizabilities. (authors). 9 refs., 18 figs., 7 tabs.

Berthot, J.; Bertin, P.Y.; Breton, V.; Fonvielle, H.; Hyde-Wright, C.; Quemener, G.; Ravel, O. [Clermont-Ferrand-2 Univ., 63 - Aubiere (France). Lab. de Physique Corpusculaire; Audit, G.; Cavata, C.; D`Hose, N.; Ducret, J.E.; Gousset, T.; Guichon, P.A.M.; Kerhouas, S.; Lhuillier, D.; Marchand, C.; Marchand, D.; Martino, J.; Mougey, J.; Roche, J.; Vernin, P. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; Ryckbosch, D.; Van de Vyver, R.; Van Hoorebeke, L.; Vanderhaegen, M. [Ghent Rijksuniversiteit (Belgium); Braghieri, A.; Pedroni, P. [Pavia Univ. (Italy); Boeglin, W.U.; Boehm, R.; Distler, M.; Edelhoff, R.; Friedrich, J.; Geiges, R.; Jennewein, P.; Kahrau, M.; Korn, M.; Kramer, H.; Krygier, K.W.; Kunde, V.; Liesenfeld, A.; Merle, K.; Neuhausen, R.; Offermann, E.A.J.M.; Pospischil, T.; Rosner, G.; Sauer, P.; Schmieden, H.; Schardt, S.; Tamas, G.; Wagner, A.; Walcher, T.; Wolf, S. [Mainz Univ. (Germany). Inst. fuer Kernphysik

1995-12-31

109

Pion cloud of the nucleon and its effect on deep-inelastic structure  

Science.gov (United States)

In this paper we present the calculation of deep-inelastic scattering structure functions of nucleons dressed by pions. The calculation is performed within the convolution model. We present analytic results for quark and antiquark distributions of a given flavor and spin and numerical results of those structure functions that are likely to be most affected by the dressing of the nucleon. We allow for the probe scattering off both nucleons and ?'s. Diagrams where it scatters off the pions themselves are not taken into account. For the numerical results we look only at combinations of structure functions where these do not contribute.

Schreiber, A. W.; Mulders, P. J.; Signal, A. I.; Thomas, A. W.

1992-05-01

110

Nucleon-nucleon scattering in the functional quantum theory of the nonlinear spinor field  

International Nuclear Information System (INIS)

[en] 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)

1979-01-01

111

Nucleon structure functions, F2(x,Q2) and xF3(x,Q2), from ?-Fe scattering at the Fermilab Tevatron  

International Nuclear Information System (INIS)

The authors present precision measurements of nucleon structure functions, F2(x,Q2) and xF3(x,Q2) from a sample of 1,320,000 ??-Fe and 280,000 bar ??-Fe high-energy charged current interactions at the Fermilab Tevatron. The CCFR measurements of xF3(x,Q2) agree in magnitude but differ in Q2 dependence, at small x, when compared to the CDHSW data; and show for the first time a Q2 evolution consistent with PQCD. The xF3 measurement leads to an accurate determination of the Gross-Llewellyn Smith sum rule. The measurements of F2(x,Q2) agree well with those from SLAC (eN) and BCDMS (?N) experiments, and lead to a precise test of the mean-square charge prediction by the Quark Parton Model. These data, however, differ from the CDHSW (?Fe) and EMC (?N) data. Measurements of the scaling violation of the CCFR F2 are also in good agreement with the theory. The preliminary value of ?MS, from the non-singlet evolution with Q2 > 15 GeV2, is 213 ± 29(stat.) ± 41(syst.) MeV. 25 refs., 13 figs., 4 tabs

1992-01-01

112

Polarized Structure Function $\\sigma_{LT'}$ for $p({\\vec e},e'K^+)\\Lambda$ in the Nucleon Resonance Region  

Energy Technology Data Exchange (ETDEWEB)

The first measurements of the polarized structure function $\\sigma_{LT'}$ for the reaction $p(\\vec e,e'K^+)\\Lambda$ in the nucleon resonance region are reported. Measurements are included from threshold up to $W$=2.05 GeV for central values of $Q^2$ of 0.65 and 1.00 GeV$^2$, and nearly the entire kaon center-of-mass angular range. $\\sigma_{LT'}$ is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate s-channel resonances, as well as resonant and non-resonant processes. The results for $\\sigma_{LT'}$ are comparable in magnitude to previously reported results from CLAS for $\\sigma_{LT}$, the real part of the same response. An intriguing sign change in $\\sigma_{LT'}$ is observed in the high $Q^2$ data at $W\\approx 1.9$ GeV. Comparisons to several existing model predictions are shown.

Nasseripour, Rakhsha; Raue, Brian; Ambrozewicz, Pawel; Carman, Daniel; Amaryan, Moscov; Amaryan, Moskov; Anciant, Eric; Anghinolfi, Marco; Asavapibhop, Burin; Asryan, Gegham; Audit, Gerard; Auger, Thierry; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Baillie, Nathan; Ball, J.P.; Ball, Jacques; Ball, J.P.; Ball, Jacques; Ball, J.P.; Ball, Jacques; Ball, J.P.; Ball, Jacques; Baltzell, Nathan; Barrow, Steve; Battaglieri, Marco; Beard, Kevin; Bedlinskiy, Ivan; Bektasoglu, Mehmet; Bellis, Matthew; Benmouna, Nawal; Berman, Barry; Biselli, Angela; Blaszczyk, Lukasz; Bonner, Billy; Bouchigny, Sylvain; Boyarinov, Sergey; Bradford, Robert; Branford, Derek; Briscoe, William; Brooks, William; Burkert, Volker; Butuceanu, Cornel; Calarco, John; Careccia, Sharon; Casey, Liam; Cetina, Catalina; Chen, Shifeng; Cheng, Lu; Cole, Philip; Collins, Patrick; Coltharp, Philip; Cords, Dieter; Corvisiero, Pietro; Crabb, Donald; Crede, Volker; Dale, Daniel; Dashyan, Natalya; De Masi, Rita; De Vita, Raffaella; De Sanctis, Enzo; Degtiarenko, Pavel; Dennis, Lawrence; Deur, Alexandre; Dhuga, Kalvir; Dickson, Richard; Djalali, Chaden; Dodge, Gail; Doughty, David; Dragovitsch, Peter; Dugger, Michael; Dytman, Steven; Dzyubak, Oleksandr; Egiyan, Hovanes; Egiyan, Kim; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fatemi, Renee; Fedotov, Gleb; Feldman, Gerald; Feuerbach, Robert; Forest, Tony; Fradi, Ahmed; Funsten, Herbert; Garcon, Michel; Gavalian, Gagik; Gevorgyan, Nerses; Gilfoyle, Gerard; Giovanetti, Kevin; Girard, Pascal; Girod, Francois-Xavier; Goetz, John; Gothe, Ralf; Gothe, Ralf; Griffioen, Keith; Guidal, Michel; Guillo, Matthieu; Guler, Nevzat; Guo, Lei; Gyurjyan, Vardan; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Hardie, John; Heddle, David; Hersman, F.; Hicks, Kenneth; Hleiqawi, Ishaq; Holtrop, Maurik; Hu, Jicun; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Ito, Mark; Jenkins, David; Jo, Hyon-Suk; Johnstone, John; Joo, Kyungseon; Juengst, Henry; Kalantarians, Narbe; Kellie, James; Khandaker, Mahbubul; Kim, Kui; Kim, Kyungmo; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Kossov, Mikhail; Krahn, Zebulun; Kramer, Laird; Kubarovsky, Valery; Kuhn, Joachim; Kuhn, Sebastian; Kuleshov, Sergey; Kuznetsov, Viacheslav; Lachniet, Jeff; Laget, Jean; Langheinrich, Jorn; Lawrence, David; Livingston, Kenneth; Lu, Haiyun; Lukashin, Konstantin; MacCormick, Marion; Manak, Joseph; Markov, Nikolai; Mattione, Paul; McAleer, Simeon; McKinnon, Bryan; McNabb, John; Mecking, Bernhard; Mestayer, Mac; Meyer, Curtis; Mibe, Tsutomu; Mikhaylov, Konstantin; Minehart, Ralph; Mirazita, Marco; Miskimen, Rory; Mokeev, Viktor; Moreno, Brahim; Moriya, Kei; Morrow, Steven; Moteabbed, Maryam; Mueller, James; Munevar Espitia, Edwin; Mutchler, Gordon; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Niczyporuk, Bogdan; Niroula, Megh; Niyazov, Rustam; Nozar, Mina; Osipenko, Mikhail; Ostrovidov, Alexander; Park, Kijun; Pasyuk, Evgueni; Paterson, Craig; Pereira, Sergio; Peterson, Gerald; Philips, Sasha; Pierce, Joshua; Pivnyuk, Nikolay; Pocanic, Dinko; Pogorelko, Oleg; Pozdnyakov, Sergey; Preedom, Barry; Price, John; Procureur, Sebastien; Prok, Yelena; Protopopescu, Dan; Qin, Liming; Riccardi, Gregory; Ricco, Giovanni; Ripani, Marco; Ritchie, Barry; Rosner, Guenther; Rossi, Patrizia; Rubin, Philip; Sabatie, Franck; Salamanca, Julian; Salgado, Carlos; Santoro, Joseph; Sapunenko, Vladimir; Sayre, Donald; Schumacher, Reinhard; Serov, Vladimir; Shafi, Aziz; Sharabian, Youri; Sharov, Dmitri; Shvedunov, Nikolay; Simionatto, Sebastio; Skabelin, Alexander; Smith, Elton; Smith, Lee; Sober, Daniel; Sokhan, Daria; Stavinsky, Aleksey; Stepanyan, Samuel; Stepanyan, Stepan; Stokes, Burnham; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Taylor, Shawn; Tedeschi, David; Thoma, Ulrike; Thompson, Richard; Tkabladze, Avtandil; Tkachenko, Svyatoslav; Ungaro, Maurizio; Vineyard, Michael; Vlassov, Alexander; Wang,

2008-06-01

113

Studying the Nucleon Structure with Spin  

International Nuclear Information System (INIS)

The BLAST (Bates Large Acceptance Spectrometer Toroid) collaboration is finalizing the analysis of a systematic study of the spin-dependent, electromagnetic interaction on hydrogen and deuterium. The experiment utilized: the highly polarized electron beam of the MIT-Bates Linear Accelerator Center stored in the South Hall Ring; an internal gas target of isotopically pure and highly polarized hydrogen or deuterium provided by an atomic beam source; and the symmetric, general purpose BLAST spectrometer. By making simultaneous measurements of many reaction channels for different combinations of beam helicity and target polarization BLAST is providing new, precise measurements for the nucleon and deuteron elastic form factors as well as studying the structure of deuterium and pion production from hydrogen and deuterium. A brief overview of the experiment will be presented together with a selection results

2007-10-26

114

Nucleon effective mass effects on the Pauli-blocking function  

Energy Technology Data Exchange (ETDEWEB)

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)

Pina, S.R. de; Mesa, J.; Deppman, A.; Arruda-Neto, J.D.T. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Duarte, S.B.; Oliveira, E.C. de; Tavares, O.A.P.; Medeiros, E.L. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Goncalves, M.; Paiva, E. de [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)]|[Sociedade Educacional Sao Paulo Apostolo - UniverCidade, Rio de Janeiro, RJ (Brazil)

2002-05-01

115

General behavior of the effective nucleon-nucleon interaction as a function of the relative velocity  

International Nuclear Information System (INIS)

We have studied volume integrals of the central part of optical potentials extracted from data analyses for a variety of light and heavy systems. The data-extracted integrals present a quite simple behavior as a function of the relative velocity between target and projectile. This behavior is system independent and, therefore, it reflects a feature of the effective nucleon-nucleon interaction itself. The overall results are in good agreement with the predictions of the Sao Paulo potential, which is a model for the nuclear interaction that so far has been employed mostly in analyses of heavy-ion reactions

2005-01-01

116

Nuclear interaction and quark structure of nucleons  

Energy Technology Data Exchange (ETDEWEB)

We discuss a procedure to construct the nucleon image of a quark operator in a non-relativistic approach. The procedure is based on the concept of mapping and establishes a correspondence between a space of three-quark clusters and a space of elementary nucleons. As an example, we search for the nucleon image of a quark hamiltonian proposed by Oka and Yazaki. The nucleon hamiltonian is hermitian, non-local and N-body (if N is the number of clusters under consideration). We construct the two-body term of this hamiltonian and search for a local effective-interaction equivalent in a harmonic-oscillator basis to the quark-derived hamiltonian. (orig.).

Catara, F. (Ist. Nazionale di Fisica Nucleare, Catania (Italy) Dipt. di Fisica, Univ. Catania (Italy)); Sambataro, M. (Ist. Nazionale di Fisica Nucleare, Catania (Italy))

1991-12-30

117

Boson-exchange nucleon-nucleon potential and nuclear structure  

International Nuclear Information System (INIS)

A fully momentum-dependent one-boson-exchange potential is derived which takes into account the mesons, ?, eta, sigma, rho, ? and phi. Scattering bound states and nuclear matter properties are studied in momentum space. The use of such potential is shown to be as easy as the use of more simple phenomenological interactions. In nuclear matter the formalism of Bethe-Goldstone is chosen to compute the binding energy versus density in the approximation of two-body and three-body correlations. The three-body correlated wave function obtained is then used

1976-01-01

118

Nuclear energy density functional from chiral two-nucleon aaand three-nucleon interactions  

Science.gov (United States)

An improved density-matrix expansion is used to calculate the nuclear energy density functional from chiral two- and three-nucleon interactions. The two-body interaction comprises long-range one- and two-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition we employ the leading-order chiral three-nucleon interaction with its parameters c E , c D and c 1,3,4 fixed in calculations of nuclear few-body systems. With this input the nuclear energy density functional is derived to first order in the two- and three-nucleon interaction. We find that the strength functions F ?( ?) and F so ( ?) of the surface and spin-orbit terms compare in the relevant density range reasonably with the results of phenomenological Skyrme forces. However, an improved description requires (at least) the treatment of the two-body interaction to second order. This observation is in line with the deficiencies in the nuclear matter equations of state bar E(? ) that remain in the Hartree-Fock approximation with low-momentum two- and three-nucleon interactions.

Holt, J. W.; Kaiser, N.; Weise, W.

2011-10-01

119

Structure functions  

International Nuclear Information System (INIS)

[en] We summarize recent developments in the understanding of nucleon structure. New data on F2, R and Fc anti c2, over a wide range of Q2 (from 104GeV2 down to 0.1 GeV2) and x (down to 10-6), are described. Conventional leading twist NLO perturbative QCD gives an excellent description of all the new data with Q2 above a GeV, leaving very little room for either higher twists or higher logarithms. We summarize the current status of NLO fits, and the determination of the gluon distribution and the strong coupling constant from structure function data. Finally we consider some of the theoretical issues raised by the new data. (orig.)

1996-01-01

120

Relativistic spectral function of nucleons in hot nuclear matter  

International Nuclear Information System (INIS)

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. Furthermore, our relativistic spectral function differs from the one in nonrelativistic approximation, used in some earlier calculations.

2010-01-01

 
 
 
 
121

Nucleon structure by Lattice QCD computations with twisted mass fermions  

International Nuclear Information System (INIS)

[en] Understanding the structure of the nucleon from quantum chromodynamics (QCD) is one of the greatest challenges of hadronic physics. Only lattice QCD allows to determine numerically the values of the observables from ab-initio principles. This thesis aims to study the nucleon form factors and the first moments of partons distribution functions by using a discretized action with twisted mass fermions. As main advantage, the discretization effects are suppressed at first order in the lattice spacing. In addition, the set of simulations allows a good control of the systematical errors. After reviewing the computation techniques, the results obtained for a wide range of parameters are presented, with lattice spacings varying from 0.0056 fm to 0.089 fm, spatial volumes from 2.1 up to 2.7 fm and several pion masses in the range of 260-470 MeV. The vector renormalization constant was determined in the nucleon sector with improved precision. Concerning the electric charge radius, we found a finite volume effect that provides a key towards an explanation of the chiral dependence of the physical point. The results for the magnetic moment, the axial charge, the magnetic and axial charge radii, the momentum and spin fractions carried by the quarks show no dependence on the lattice spacing nor volume. In our range of pion masses, their values show a deviation from the experimental values. Their chiral behaviour do not exhibit the curvature predicted by the chiral perturbation theory which could explain the apparent discrepancy. (author)

2010-01-01

122

Understanding nucleon structure using lattice simulations. Recent progress on three different structural observables  

Energy Technology Data Exchange (ETDEWEB)

This review focuses on the discussion of three key results of nucleon structure calculations on the lattice. These three results are the quark contribution to the nucleon spin, J{sub q}, the nucleon-{delta} transition form factors, and the nucleon axial coupling, g{sub A}. The importance for phenomenology and experiment is discussed and the requirements for future simulations are pointed out. (orig.)

Schroers, W. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

2007-01-15

123

Relativistic spectral function of nucleon in hot nuclear matter  

CERN Document Server

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 evaluation in the non-relativistic limit carried out earlier differ from the present relativistic one by as much as 25 %.

Ghosh, Sabyasachi; Sarkar, Sourav

2010-01-01

124

Evolution of nucleon structure functions in the Q/sup 2/ range between 20 and 10 000 GeV/sup 2/ from a new QCD analysis of neutrino data  

Energy Technology Data Exchange (ETDEWEB)

From the nucleon structure functions measured by the CHARM Collaboration in inclusive neutrino and antineutrino CC interactions we determined the QCD parameter ..lambda..sub(MS) = 310 +- 140 (stat.) +- 70 (syst.) MeV using the Furmanski-Petronzio method. With the same method we extrapolated the behaviour of the quark (q + q) and the gluon x-distributions up to Q/sup 2/ = 10000 GeV/sup 2/ using perturbative QCD. The extrapolated structure functions are compared with recent results coming from the two-jet differential cross section in proton-antiproton interactions at ..sqrt..s = 540 GeV and Q/sup 2/ = 2000 GeV/sup 2/.

Bergsma, F.; Dorenbosch, J.; Allaby, J.V.; Amaldi, U.; Barbiellini, G.; Flegel, W.; Lanceri, L.; Metcalf, M.; Nieuwenhuis, C.; Panman, J.

1985-03-21

125

p+rvec d?3He+? reaction with realistic three-nucleon wave functions  

International Nuclear Information System (INIS)

[en] We study the proton-deuteron radiative capture reaction at low energies (E? congruent 10 MeV) with the three-nucleon Faddeev wave functions for various combinations of available realistic nucleon-nucleon potentials and the two-pion exchange three-nucleon potential. The calculated values of tensor analyzing power Ayy(?) are found to be sensitive to a different choice of realistic potentials and introduction of the three-nucleon potential. The comparison with available data shows the necessity of the three-nucleon potential

1992-01-01

126

Nucleon-nucleon interactions  

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 ?2 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.

1996-01-01

127

Structure functions in chorus  

International Nuclear Information System (INIS)

In this report a nucleon structure function analysis will be discussed. In CHORUS experiment, lead-scintillator calorimeter was used as active target and in 1998 run a high statistics sample of CC interactions of muon (anti-) neutrinos were collected. This sample was used to extract the structure functions of the nucleons in neutrino interactions. A Monte-Carlo program has been developed to study the efficiencies of the detector and for the proper corrections to be applied to the data. The structure functions, F1, F2, xF3, were extracted using three different kinds of fits. The effects of different systematic dependencies have also been studied. Results have been compared to the earlier experiments, CCFR and CDHSW.

2004-01-01

128

Spin structure functions  

Energy Technology Data Exchange (ETDEWEB)

Recently published experimental results on the polarized structure function g{sub 1}(x, Q{sup 2}) of the proton, neutron and deuteron have been used in next to leading order QCD fits to provide constraints on the polarized parton distribution functions. Semi-inclusive measurements, sensitive to flavour-specific distributions, will remove some of the uncertainties due to theoretical assumption. Determination of the orbital angular momentum contribution is necessary for a complete understanding of nucleon spin.

Young, C.C. [Stanford Univ., CA (United States). Stanford Linear Accelerator Center

1998-12-31

129

Unpolarized Structure Functions  

International Nuclear Information System (INIS)

Over the past decade measurements of unpoiarized structure functions with unprecedented precision have significantly advanced our knowledge of nucleon structure. These have for the first time allowed quantitative tests of the phenomenon of quark-hadron duality, and provided a deeper understanding of the transition from hadron to quark degrees of freedom in inclusive scattering. Dedicated Rosenbluth-separation experiments have yielded high-precision transverse and longitudinal structure functions in regions previously unexplored, and new techniques have enabled the first glimpses of the structure of the free neutron, without contamination from nuclear effects.

2011-05-01

130

Unpolarized Structure Functions  

Energy Technology Data Exchange (ETDEWEB)

Over the past decade measurements of unpolarized structure functions with unprecedented precision have significantly advanced our knowledge of nucleon structure. These have for the first time allowed quantitative tests of the phenomenon of quark-hadron duality, and provided a deeper understanding of the transition from hadron to quark degrees of freedom in inclusive scattering. Dedicated Rosenbluth-separation experiments have yielded high-precision transverse and longitudinal structure functions in regions previously unexplored, and new techniques have enabled the first glimpses of the structure of the free neutron, without contamination from nuclear effects.

M. E. Christy,W. Melnitchouk

2011-06-01

131

The triton binding energy and the nd-scattering lengths with account of a quark nucleon structure  

International Nuclear Information System (INIS)

A simple model for the nucleon-nucleon interaction is suggested which takes into account the quark nucleon structure. Using this model the triton binding energy and the nd-scattering lengths are calculated.

1983-01-01

132

Transverse spin structure of the nucleon from lattice QCD simulations  

Energy Technology Data Exchange (ETDEWEB)

We present the first calculation in lattice QCD of the lowest two moments of transverse spin densities of quarks in the nucleon. They encode correlations between quark spin and orbital angular momentum. Our dynamical simulations are based on two flavors of clover-improved Wilson fermions and Wilson gluons. We find significant contributions from certain quark helicity flip generalized parton distributions, leading to strongly distorted densities of transversely polarized quarks in the nucleon. In particular, based on our results and recent arguments by Burkardt [Phys. Rev. D 72 (2005) 094020], we predict that the Boer-Mulders-function h{sub 1} {sup perpendicular} {sup to}, describing correlations of transverse quark spin and intrinsic transverse momentum of quarks, is large and negative for both up and down quarks. (orig.)

Goeckeler, M.; Schaefer, A. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik; Haegeler, P. [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y.; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division, Dept. of Mathematical Sciences; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB) (Germany)

2006-12-15

133

Sum Rules for Nucleon GPDs and Border Function Formulation  

Energy Technology Data Exchange (ETDEWEB)

Recently developed new approach to model nucleon generalized parton distributions (GPDs) H and E is based on two types of their representation in terms of double distributions. Within this approach, we re-consider the derivation of GPD sum rules that allow to use border functions H(x,x) and E(x,x) instead of full GPDs H(x,\\xi) and E(x,\\xi) in the integrals producing Compton form factors of deeply virtual Compton scattering. Using factorized DD Ansatz to model GPDs, we discuss the relation between the border functions and underlying parton densities. We found that substantial contribution to H(x,x) border function comes from the extra term required by new DD representations and related to E(x,\\xi) GPD.

Radyushkin, Anatoly V. [JLAB, Old Dominion U., JINR

2013-09-01

134

Some information from nucleon-antinucleon annihilation at rest: e+e- annihilation, hadronic fragmentation, and deep inelastic scattering structure function  

CERN Document Server

The experimental spectra of charged pions in NN annihilation at rest are described in a model of quasi-two-body decays. The same model predicts the pi /sup 0/, s, rho 's and omega 's spectra. These calculations are used to determine, in the vector dominance model, the pion spectra in the e/sup +/e/sup -/ annihilation at the same energy. The NN system is then used as a heavy hadron in order to describe, in a model-independent way: the projectile fragmentation part in inclusive reactions; the valence part of the deep inelastic structure function. (0 refs).

Pelaquier, E

1974-01-01

135

Anomalous behaviour of nuclear structure functions revisited  

International Nuclear Information System (INIS)

If a nucleus is regarded as a collection of quasi-free nucleons, the nuclear structure functions are simply proportional to the corresponding structure functions of the nucleon. It has been argued that the conventional picture of the nucleus might not hold when the nucleus is probed during a very short time. A simple parton model has been formulated, illustrating the idea of an anomalous behaviour of nuclear structure functions. The nucleus is pictured as one bag of partons

1983-07-01

136

Studies of the three-nucleon system properties using the interpolating amplitude scattering function  

International Nuclear Information System (INIS)

The three-nucleon motion problem is formulated and investigated using the interpolating function method. The pole functions corresponding to the bound state of the three-nucleon system and the low energy functions interpolating the nd-scattering length are calculated for a separable potential

1985-01-01

137

Muon-nucleon, deep inelastic scattering: determination of the ratio R = sigma sub(L)/sigma sub(T) and comparison of structure functions to QCD predictions  

International Nuclear Information System (INIS)

[en] Using the structure functions F2 measured in E.M.C., we have extracted the following values for the QCD scale parameter ?, at next to leading order: hydrogen target: ?sub(MS) = 139(+170-100)MeV; iron target: ?sub(MS) = 170(+160-100)MeV we have performed a study of the 1/Q2 effects on the Q2 domain covered by SLAC and E.M.C. We have extracted the ratio R = sigma sub(L)/sigma sub(T) for various chi bins and compared it with other experimental values and theoretical predictions. The mean value = 0+-.15 was found and is compatible with zero

1982-01-01

138

Nucleon-meson vertex functions and isobar-meson vertex functions from quark potential model  

Energy Technology Data Exchange (ETDEWEB)

The matrix elements of the nucleon-meson vertices and isobar-meson vertices due to one gluon exchange transition potential are calculated by using the generator coordinate method. The coupling constants of the vertices are in good agreement with the experimental data and the form factors of the factors of the vertices are much like the Gaussian functions.

Yu You-Wen; Zhang Zong-Ye

1985-03-01

139

Nucleon-nucleon interactions  

Energy Technology Data Exchange (ETDEWEB)

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 {ital 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 {ital v}{sub 18} potential, one of a number of new potentials that fit elastic nucleon-nucleon data up to 350 MeV with a {Chi}{sup 2} 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 {ital NN} interactions. We conclude with some remarks on how our empirical knowledge of {ital NN} interactions may help constrain models at the quark level, and hence models of nucleon structure.

Wiringa, R.B.

1996-12-31

140

A Haplousterotic Model for the Nucleon Wave Function  

CERN Document Server

We review the consequences of the sensitivity of the relation between t= he moments of a model for the nucleon quark distribution amplitude and the coefficients of its polynomial expansion. Criteria for a simpler approach= to constructing a model for the quark distribution amplitude are formulated.= We describe how such a simpler (or "haplousterotic") model for the quark distribution amplitude of the nucleon is obtained from the QCD sum-rule m= oments of COZ.

Eckardt, R; Gari, M F; Eckardt, Robert; Gari, Manfred F.

1996-01-01

 
 
 
 
141

Spin Structure Functions in a Covariant Spectator Quark Model  

Energy Technology Data Exchange (ETDEWEB)

We apply the covariant spectator quark–diquark model, already probed in the description of the nucleon elastic form factors, to the calculation of the deep inelastic scattering (DIS) spin-independent and spin-dependent structure functions of the nucleon. The nucleon wave function is given by a combination of quark–diquark orbital states, corresponding to S, D and P-waves. A simple form for the quark distribution function associated to the P and D waves is tested.

G. Ramalho, Franz Gross and M. T. Peña

2010-12-01

142

Overlap functions in nuclear correlation methods and direct nucleon removal processes  

International Nuclear Information System (INIS)

[en] A theoretical method to obtain overlap functions and spectroscopic factors from a model one-body density matrix (OBDM) accounting for short-range nucleon-nucleon correlations is applied to describe one-nucleon removal processes on the 16O and 40Ca nuclei. The method allows the differential cross sections of (p,d) reactions and the momentum distributions of transitions to single-particle states from (e, e'p) reactions to be calculated. It is shown that the overlap functions obtained within the Jastrow correlation method lead to a satisfactory description of the quantities considered. 24 refs., 3 figs., 1 tab

1996-01-01

143

Investigation of the nucleon electromagnetic structure by polarization effects in e+e->NantiN processes  

International Nuclear Information System (INIS)

Polarization effects in e+e-->NantiN processes are investigated form various aspects. The sensitivity in a behaviour of the vector polarization components of the nucleon is demonstrated graphically by using two recent formulations of the unitary and analytic VMD model of the nucleon electromagnetic structure. 14 refs.; 4 figs.

1992-01-01

144

Leading nucleons from peripheral processes in lepton deep inelastic scattering and the nucleon structure  

CERN Multimedia

The experimental information on nucleon production in lepton deep inelastic scattering (DIS) is rather scarce. Recently there is a growing interest in understanding the mechanism of the production of baryons in DIS, stimulated by recent results on leading protons and neutrons from electron-proton scattering at HERA. I review on different peripheral mechanisms of nucleon (proton or neutron) production in lepton DIS and discuss their role in understanding the spectra of nucleons for both fixed target and collider experiments. In DIS ep to e'Xh, the QCD hardness scale gradually diminishes from the hard scale, Q/sup 2/, in the virtual photon (current) fragmentation region to the soft, hadronic, scale in the proton (target) fragmentation region. This suggests a similarity of the inclusive spectra of leading protons and neutrons, h=p, n, in high energy hadron-proton collisions and in lepton DIS at small Bjorken-x. The semi-inclusive cross section for production of slow protons in charged-current deep inelastic (ant...

Szczurek, A

1999-01-01

145

Elastic pp scattering in the soft-nucleon-structure model  

International Nuclear Information System (INIS)

[en] A quark-gluon pattern of elastic pp scattering is constructed on the basis of the soft-nucleon-structure model initially intended for describing ep scattering at low momentum transfers and supplemented here with the hypothesis of a photonlike Pomeron. This pattern demonstrates the universality of the proton structure in electromagnetic and hadronic processes. Special features of angular distributions for ?(s)>10 GeV are explained by rescattering on a diquark constituent of the proton. It is shown that the behavior of the differential cross section beyond the first and second maxima is determined, respectively, by the quark distribution for x?1 and by the gluon distribution for x?0.01-0.001. According to the proposed model, the Regge behavior of the total and differential cross sections is associated with changes undergone by the state of constituent quarks as the result of interaction. On basis of parameters obtained by fitting data on elastic ep scattering it is found that the supercritical behavior of the Pomeron in photoproduction processes is characterized by the value of ??0.12

1198-01-00

146

Hadron wave functions and the issue of nucleon deformation  

CERN Multimedia

Using gauge invariant hadronic two- and three- density correlators we extract information on the spatial distributions of quarks in hadrons, and on hadron shape and multipole moments within quenched lattice QCD. Combined with the calculation of N to Delta transition amplitudes the issue of nucleon deformation can be addressed.

Alexandrou, C; Tsapalis, A; Forcrand, Ph. de

2003-01-01

147

Nucleon nucleon diffraction  

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)

1980-05-09

148

Non-Standard Model of the Nucleon Electromagnetic Structure and its Predictability  

CERN Multimedia

Unitary and analytic ten-resonance model of the nucleon electromagnetic (e.m.) structure with canonical normalizations and asymptotics is constructed on a four-sheeted Riemann surface. It describes well all existing experimental space-like and time-like data on the nucleon e.m. form factors (ff's), including also FENICE (Frascati) results on the neutron, for the first time. This is achieved without any external constraints on the isovector spectral functions following from the piN-scattering data and pion e.m. ff behaviour through the unitarity condition. Just opposite, the model itself predicts a pronounced effect of the two-pion continuum on the isovector spectral functions revealing the strong enhancement of the left wing of the rho(770)-resonance close to two-pion threshold. The existence of the fourth excited state of the rho(770) meson with parameters mass and width equal to 2506 MeV and 700 MeV, respectively. The isoscalar spectral function behaviours are predicted by the presented model.

Dubnicka, S; Weisenpacher, P

2000-01-01

149

Transverse strange quark spin structure of the nucleon  

CERN Multimedia

We investigate the transverse quark spin densities of the nucleon with the lowest moment within the framework of the SU(3) chiral quark-soliton model, emphasizing the strange quark. Based on previous results of the vector and tensor form factors, we are able to determine the impact-parameter dependent probability densities of transversely polarized quarks in an unpolarized nucleon as well as those of unpolarized quarks in a transversely polarized nucleon. We find that the present numerical results for the transverse spin densities of the up and down quarks are in good agreement with those of the lattice calculation. We predict the transvere spin densities of the strange quark. It turns out that the polarized strange quark is noticeably distorted in an unpolarized proton.

Ledwig, Tim

2011-01-01

150

The Light-flavor structure of the nucleon  

CERN Multimedia

Recent data on the Gottfried sum and less recent ones on the pion-nucleon sigma term seem to disagree with naive parton-based expectations on the light (i.e., up, down and strange) quark content of the nucleon. We show that these discrepancies are resolved if nonperturbative contributions are included in the analysis of the data. These appear both in the computation of matrix elements of operators, and in their QCD scale dependence, and depend strongly on the quantum numbers of the given state.

Forte, Stefano

1994-01-01

151

Nucleon Structure in Lattice QCD using twisted mass fermions  

CERN Multimedia

We present results on the nucleon form factors and moments of generalized parton distributions obtained within the twisted mass formulation of lattice QCD. We include a discussion of lattice artifacts by examining results at different volumes and lattice spacings. We compare our results with those obtained using different discretization schemes and to experiment.

Alexandrou, C; Korzec, T; Carbonell, J; Harraud, P A; Papinutto, M; Guichon, P; Jansen, K

2010-01-01

152

Polarized structure functions a status report  

CERN Document Server

We review the present status of polarized structure functions measured in deep-inelastic scattering. We discuss the x and Q^2 dependence of the structure function g_1, and how it can be used to test perturbative QCD at next-to-leading order and beyond. We summarize the current knowledge of polarized parton distributions, in particular the determination of the first moment of the quark and gluon distributions and the axial charge of the nucleon. We critically examine what future experiments could teach us on the polarized structure of the nucleon.

Forte, Stefano

1996-01-01

153

Nucleon structure in terms of OPE with non-perturbative Wilson coefficients  

Energy Technology Data Exchange (ETDEWEB)

Lattice calculations could boost our understanding of Deep Inelastic Scattering by evaluating moments of the Nucleon Structure Functions. To this end we study the product of electromagnetic currents between quark states. The Operator Product Expansion (OPE) decomposes it into matrix elements of local operators (depending on the quark momenta) and Wilson coefficients (as functions of the larger photon momenta). For consistency with the matrix elements, we evaluate a set of Wilson coefficients non-perturbatively, based on propagators for numerous momentum sources, on a 24{sup 3} x 48 lattice. The use of overlap quarks suppresses unwanted operator mixing and lattice artifacts. Results for the leading Wilson coefficients are extracted by means of Singular Value Decomposition. (orig.)

Bietenholz, W. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik; Cundy, N.; Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Pleiter, D.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division, Dept. of Mathematical Sciences

2008-10-15

154

Overlap functions in correlation methods and quasifree nucleon knockout from $^{16}O$  

CERN Multimedia

The cross sections of the ($e,e'N$) and ($\\gamma,p$) reactions on $^{16}$O are calculated, for the transitions to the $1/2^{-}$ ground state and the first $3/2^{-}$ excited state of the residual nucleus, using single-particle overlap functions obtained on the basis of one-body density matrices within different correlation methods. The electron-induced one-nucleon knockout reaction is treated within a nonrelativistic DWIA framework. The theoretical treatment of the ($\\gamma,p$) reaction includes both contributions of the direct knockout mechanism and of meson-exchange currents. The results are sensitive to details of the different overlap functions. The consistent analysis of the reaction cross sections and the comparison with the experimental data make it possible to study the nucleon--nucleon correlation effects.

Gaidarov, M K; Antonov, A N; Stoitsov, M V; Dimitrova, S S; Giusti, C

2000-01-01

155

Nucleon structure at small x: recent results from HERA  

International Nuclear Information System (INIS)

Measurements of structure functions and of the hadronic final state in deep inelastic scattering at HERA are presented. The results comprise the extraction of parton densities, measurements of the strong coupling, and the search for novel QCD effects in the new kinematic regime at HERA

1997-01-01

156

Understanding the structure of the nucleon and the origin of its mass from first principles of quantum chromodynamics. How much sea quark contributes to the nucleon mass?  

International Nuclear Information System (INIS)

The sigma term represents the quark contribution to the nucleon mass. It is useful for understanding the structure of the nucleon and is also a key parameter for precision experiments in particle physics and cosmology, which use nucleons as the target. However, the sigma term, in particular the strange quark contribution, has been only poorly determined by the standard analysis of the pion-nucleon scattering using the chiral perturbation theory. Therefore, the theoretical determination of the sigma term from the first principles of QCD has been awaited. Recently, owing to the development of lattice QCD with exact chiral symmetry by the JLQCD collaboration, a reliable determination of the sigma term is becoming possible for the first time. In this article, we introduce our study of the sigma term from the first principle based on our lattice QCD calculation. We also mention about the possible impact of our study to the dark matter direct detection experiment and flavor physics. (author)

2009-01-01

157

Pion and nucleon structure as probed in the reaction ?/sup +-/N ? ?+?-X at 253 GeV  

International Nuclear Information System (INIS)

New results are presented from Fermilab experiment E615, in which hadroproduction of muon pairs allows a determination of the quark structure of the initial-state hadrons in the context of a Drell-Yan model. Comparison of muon-pair production by ?+ and ?- beams shows the cross-section ratio follows Drell-Yan model expectations, except for a dip in ?(?+)/?(?-) near x/sub ?/ near 1. The same data are also used to extract the ratio of the sea to valence quark distributions in the nucleon, with improved accuracy for x/sub N/ 2 for the ?- data sample. This provides stronger evidence of a rise in the nucleon structure function for x/sub N/

1988-01-01

158

Self-consistent Green's functions calculation of the nucleon mean-free path  

CERN Multimedia

The extension of Green's functions techniques to the complex energy plane provides access to fully dressed quasi-particle properties from a microscopic perspective. Using self-consistent ladder self-energies, we find both spectra and lifetimes of such quasi-particles in nuclear matter. With a consistent choice of the group velocity, the nucleon mean-free path can be computed. Our results indicate that, for energies above 50 MeV at densities close to saturation, a nucleon has a mean-free path of 4 to 5 femtometers.

Rios, A

2011-01-01

159

Structure functions and parity violation in supersymmetric QCD  

International Nuclear Information System (INIS)

Two topics in supersymmetric QCD are shortly reviewed the structure functions in unpolarized and polarized lepton-nucleon scattering and the influence of possible parity violation on the deep inelastic scattering

1986-01-01

160

A pure $S$-wave covariant model for the nucleon  

Energy Technology Data Exchange (ETDEWEB)

Using the manifestly covariant spectator theory, and modeling the nucleon as a system of three constituent quarks with their own electromagnetic structure, we show that all four nucleon electromagnetic form factors can be very well described by a manifestly covariant nucleon wave function with zero orbital angular momentum.

Franz Gross; G. Ramalho; M.T. Pena

2008-01-01

 
 
 
 
161

Is nucleon deformed?  

International Nuclear Information System (INIS)

[en] The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter PD ?1/4 (which specifies deformation) fits gA (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(?N?), the double delta coupling constant1 fsub(???), the Ml transition moment ??N and g1p the spin structure function of proton2. All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs

1992-01-01

162

Optical potentials for nuclear level structures and nucleon interactions data of tin isotopes based on the soft-rotator model  

International Nuclear Information System (INIS)

The soft-rotator model is applied to self-consistent analyses of the nuclear level structures and the nucleon interaction data of the even-even Sn isotopes, 116Sn, 118Sn, 120Sn, and 122Sn. The model successfully describes low-lying collective levels of these isotopes, which exhibit neither typical rotational nor harmonic vibrational structures. The experimental nucleon interaction data--total neutron cross sections, proton reaction cross sections, and nucleon elastic and inelastic scattering data--are well described up to 200 MeV in a coupled-channels optical model approach. For the calculations, nuclear wave functions for the Sn isotopes are taken from the nonaxial soft-rotator model with the model parameters adjusted to fit the measured low-lying collective level structures. We find that the ?2 and ?3 deformations for incident protons are larger than those for incident neutrons by ?15%, which is clear evidence of the deviation from the pure collective model for these isotopes.

2009-01-01

163

Evolution of the nucleon structure in light nuclei  

International Nuclear Information System (INIS)

The evolution of the EMC effect as a function of atomic mass A is considered for the first time for the lightest nuclei, D, 3He and , 4He, with an approach based on the Bethe-Salpeter formalism. We show that the pattern of the oscillation of the ratio rA(x)=F2A/F2N(D) with respect to the line rA(x)=1 varies with A, unlike the pattern for nuclei with masses A>4, where only the amplitude of the oscillation changes. It is found that the shape of the structure function distortions, which is typical for metals, is being reached in 3He

1998-01-01

164

Lattice Investigations of Nucleon Structure at Light Quark Masses  

CERN Multimedia

Lattice simulations of hadronic structure are now reaching a level where they are able to not only complement, but also provide guidance to current and forthcoming experimental programmes at, e.g. Jefferson Lab, COMPASS/CERN and FAIR/GSI. By considering new simulations at low quark masses and on large volumes, we review the recent progress that has been made in this exciting area by the QCDSF/UKQCD collaboration. In particular, results obtained close to the physical point for several quantities, including electromagnetic form factors and moments of ordinary parton distribution functions, show some indication of approaching their phenomenological values.

Göckeler, M; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schäfer, A; Schierholz, G; Stüben, H; Zanotti, J M

2009-01-01

165

On the treatment of the nuclear matter problem with phenomenological and realistic nucleon-nucleon interactions in the framework of the Green function  

International Nuclear Information System (INIS)

[en] We performed a self-consistent calculation of the nuclear matter properties within the Green's function scheme. Essential is the self-energy ?(p;epsilon) (effective single-particle potential or mass operator), which determines the properties of the system. Necessary for the calculation of the effective single-particle potential is the knowledge of the scattering matrix (T-matrix) in matter, which plays in the calculation the role of an effective two-body potential. Our calculations were performed for the 'phenomenological' hardcore potential of Hamada-Johnston, the Reid-soft-core potential and the 'realistic' Paris-Nucleon-Nucleon potential. A binding energy of -5.88 MeV per nucleon was obtained. For the Reid-soft-core potential and the Paris potential we found -11 MeV and -12.2 MeV respectively. (orig./HSI)

1985-01-01

166

The Isospin structure of the 3-nucleon form-factors  

International Nuclear Information System (INIS)

Isospin is a good symmetry for the strong interaction. Nuclear observables are therefore easier to interpret by considering their isospin projections. The properties of the electromagnetic current of hadrons impose isospin 0 and 1 to be the relevant components for nuclear studies with electromagnetic probes. Thus, an isoscalar-isovector separation is not simply another way of presenting data. It helps to disentangle different physical processes that are mixed before separation. The purpose of the present contribution is to give the results of such a separation in the case of the 3-nucleon form factors. This approach may also be useful for a comparison of electromagnetic and weak properties: the electromagnetic observables have both components, whereas the charged weak interactions (such as beta-decay or muon-capture) are purely of isovector character

1986-01-01

167

Single-Particle Structure of Radioactive Beams from One-Nucleon Knockout Reactions  

Energy Technology Data Exchange (ETDEWEB)

Studies of the single-particle structure of radioactive beams produced in fragmentation reactions are described. The experiments are based on observing the individual final states of the projectile residues produced in one-nucleon knockout reactions. The measured partial cross sections to the various final states of the projectile residue and the shape of the corresponding longitudinal momentum distributions reflect the single particle properties, spectroscopic factors and the angular momentum l of the removed nucleon. Applications to {sup 26,27}P and {sup 15}C are discussed.

A. Navin; T. Aumann; D. Bazin; B.A. Brown; T. Glasmacher; P.G. Hansen; R.W. Ibbotson; V. Maddalena; B.M. Sherrill; J.A. Tostevin; J. Yurkon

1999-12-31

168

Effect of nucleon and hadron structure changes in-medium and its impact on observables  

Energy Technology Data Exchange (ETDEWEB)

We study the effect of hadron structure changes in a nuclear medium using the quark-meson coupling (QMC) model. The QMC model is based on a mean field description of non-overlapping nucleon (or baryon) bags bound by the self-consistent exchange of scalar and vector mesons in the isoscalar and isovector channels. The model is extended to investigate the properties of finite nuclei, in which, using the Born-Oppenheimer approximation to describe the interacting quark-meson system, one can derive the effective equation of motion for the nucleon (or baryon), as well as the self-consistent equations for the meson mean fields.

K. Saito; K. Tsushima; A.W. Thomas

2005-07-05

169

Polarized Structure of Nucleon in the Valon Representation  

CERN Multimedia

We have utilized the concept of valon model to calculate the spin structure functions of proton, neutron and deuteron. The valon structure itself is universal and arises from the perturbative dressing of the valence quark in QCD. Our results agree rather well with all the relevant experimental data on $g_{1}^{p, n, d}$ and $g_{A}/g_{v}$, and suggests that the sea quark contribution to the spin of proton is consistent with zero. It also reveals that while the total quark contribution to the spin of valon is almost constant at $Q^{2}>=1$ the gluon contribution grows with the increase of $Q^2$ and hence requiring a sizable negative orbital angular momentum component $L_z$. This component along with the singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD. We speculate that gluon contribution to the spin content of the proton is about 60% for all $Q^2$ values. Finally, we show that the size of gluon polarization and hence, $L_{z}$, is sensitive to the initial scale$Q_{0}^{2}$.

Arash, Firooz

2007-01-01

170

Polarized structure of nucleon in the valon representation  

International Nuclear Information System (INIS)

We have utilized the concept of valon model to calculate the spin structure functions of proton, neutron, and deuteron. The valon structure itself is universal and arises from the perturbative dressing of the valence quark in QCD. Our results agree rather well with all of the relevant experimental data on g1p,n,d and gA/gV, and suggests that the sea quark contribution to the spin of proton is consistent with zero. It also reveals that while the total quark contribution to the spin of a valon, ??valon, is almost constant at Q2 ? 1 the gluon contribution grows with the increase of Q2 and hence requiring a sizable negative orbital angular momentum component Lz. This component along with the singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD . We speculate that gluon contribution to the spin content of the proton is about 60% for all Q2 values. Finally, we show that the size of gluon polarization and hence, Lz, is sensitive to the initial scale Q02.

2007-01-01

171

Quark-hadron duality in structure functions  

International Nuclear Information System (INIS)

I review recent developments in quark-hadron duality in inclusive electron-nucleon scattering. Matrix elements of twist-4 operators extracted from moments of the spin-dependent g1 structure function suggest that duality violating higher twists are small above Q2 ? 1 GeV2. The x dependence of local duality is analyzed within a quark model framework, and mechanisms are identified for spin-flavor symmetry breaking which underpin the behavior of structure functions at large x

2004-01-01

172

Quark-hadron duality in structure functions  

Energy Technology Data Exchange (ETDEWEB)

I review recent developments in quark-hadron duality in inclusive electron-nucleon scattering. Matrix elements of twist-4 operators extracted from moments of the spin-dependent g1 structure function suggest that duality violating higher twists are small above Q2 {approx} 1 GeV2. The x dependence of local duality is analyzed within a quark model framework, and mechanisms are identified for spin-flavor symmetry breaking which underpin the behavior of structure functions at large x.

Wally Melnitchouk

2004-10-01

173

The $g_2$ Structure Function  

CERN Multimedia

Polarized structure functions at low $Q^2$ have the physical interpretation of (generalized) spin polarizabilities. At high $Q^2$, the polarized parton distribution $g_2(x)$ provides access to quark-gluon correlations in the nucleon. We discuss the interpretation of the $x^2$ moment of $\\bar{g}_2(x)$ as an average transverse force on quarks in deep-inelastic scattering from a transversely polarized target. Qualitative connections with generalized parton distributions are emphasized. The $x^2$ moment of the chirally-odd twist-3 parton distribution $e(x)$ provides information on the dependence of the average transverse force on the transversity of the quark.

Burkardt, Matthias

2009-01-01

174

Study of the universal function of nuclear proximity potential between {alpha} and nuclei from density-dependent nucleon-nucleon interaction  

Energy Technology Data Exchange (ETDEWEB)

The universal function of proximity potential between {alpha} and nuclei is systematically studied from the double-folding model with the density-dependent nucleon-nucleon interaction (CDM3Y6) by analyzing different target nuclei with Z=48-92. The analytical formula of universal function is obtained at s{sub 0}>-1 by fitting all of the calculated values. Using this formula we calculate the half-lives of {alpha} decay for heavy nuclei in comparison with the values of the experimental data. It is shown that the half-lives of the {alpha} decay calculated from the presently obtained universal function in proximity potential can keep within a factor of 3 with the experimental data. (orig.)

Zhang, G.L. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Beihang University, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing (China); Zheng, H.B.; Qu, W.W. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China)

2013-01-15

175

The Structure of the Nucleon and its Excited States  

International Nuclear Information System (INIS)

The past year has been an exciting and productive one for particle physics research at Abilene Christian University. The thrust of our experimental investigations is the study of the nucleon and its excited states. Laboratories where these investigations are presently being conducted are the AGS at Brookhaven, Fermilab and LAMPF. Some analysis of the data for experiments at the Petersburg Nuclear Physics Institute (Gatchina, Russia) is still in progress. Scheduling of activities at different laboratories inevitably leads to occasional conflicts. This likelihood is increased by the present budget uncertainties at the laboratories that make long-term scheduling difficult. For the most part, the investigators have been able to avoid such conflicts. Only one experiment received beam time in 1994 (E890 at the AGS). The situation for 1995-1996 also appears manageable at this point. E890 and another AGS experiment (E909) will run through May, 1995. El 178 at LAMPF is presently scheduled for August/September 1995. E866 at Fermilab is scheduled to start in Spring/Summer 1996. Undergraduate student involvement has been a key element in this research contract since its inception. Summer students participated at all of the above laboratories in 1994 and the same is planned in 1995. A transition to greater involvement by graduate students will provide cohesiveness to ACU involvement at a given laboratory and full-time on-site involvement in the longer running experiments at FNAL and BNL. Funds to support a full-time graduate student are requested this year. Finally, collaboration by Russian, Croatian and Bosnian scientists has proven to be mutually beneficial to these experimental programs and to the overall programs at the institutions involved. Past support has been augmented by other grants from government agencies and from the Research Council at Abilene Christian University. Additional funds are requested in this renewal to enable more programmatic support for these efforts, so that long-range plans can be made to carry out the experiments and to perform the analysis

1995-01-01

176

Spin and orbital angular momentum in gauge theories (II): QCD and nucleon spin structure  

CERN Document Server

Parallel to the construction of gauge invariant spin and orbital angular momentum for QED in paper (I) of this series, we present here an analogous but non-trivial solution for QCD. Explicitly gauge invariant spin and orbital angular momentum operators of quarks and gluons are obtained. This was previously thought to be an impossible task, and opens a more promising avenue towards the understanding of the nucleon spin structure.

Chen, X S; Sun, W M; Wang, F; Goldman, T

2007-01-01

177

NUCLEON STRUCTURE IN LATTICE QCD WITH DYNAMICAL DOMAIN--WALL FERMIONS QUARKS.  

Energy Technology Data Exchange (ETDEWEB)

We report RBC and RBC/UKQCD lattice QCD numerical calculations of nucleon electroweak matrix elements with dynamical domain-wall fermions (DWF) quarks. The first, RBC, set of dynamical DWF ensembles employs two degenerate flavors of DWF quarks and the DBW2 gauge action. Three sea quark mass values of 0.04, 0.03 and 0.02 in lattice units are used with 220 gauge configurations each. The lattice cutoff is a{sup -1} {approx} 1.7GeV and the spatial volume is about (1.9fm){sup 3}. Despite the small volume, the ratio of the isovector vector and axial charges g{sub A}/g{sub V} and that of structure function moments {sub u-d}/{sub {Delta}u-{Delta}d} are in agreement with experiment, and show only very mild quark mass dependence. The second, RBC/UK, set of ensembles employs one strange and two degenerate (up and down) dynamical DWF quarks and Iwasaki gauge action. The strange quark mass is set at 0.04, and three up/down mass values of 0.03, 0.02 and 0.01 in lattice units are used. The lattice cutoff is a{sup -1} {approx} 1.6GeV and the spatial volume is about (3.0fm){sup 3}. Even with preliminary statistics of 25-30 gauge configurations, the ratios g{sub A}/g{sub V} and {sub u-d}/{sub {Delta}u-{Delta}d} are consistent with experiment and show only very mild quark mass dependence. Another structure function moment, d{sub 1}, though yet to be renormalized, appears small in both sets.

LIN H.-W.; OHTA, S.

2006-10-02

178

Nucleon structure in lattice QCD with dynamical domain-wall fermions quarks  

Energy Technology Data Exchange (ETDEWEB)

We report RBC and RBC/UKQCD lattice QCD numerical calculations of nucleon electroweak matrix elements with dynamical domain-wall fermions (DWF) quarks. The first, RBC, set of dynamical DWF ensembles employs two degenerate flavors of DWF quarks and the DBW2 gauge action. Three sea quark mass values of 0.04, 0.03 and 0.02 in lattice units are used with about 200 gauge configurations each. The lattice cutoff is about 1.7 GeV and the spatial volume is about (1.9 fm){sup 3}. Despite the small volume, the ratio of the isovector vector and axial charges g{sub A}/g{sub V} and that of structure function moments {sub u-d}/{sub {Delta} u - {Delta} d} are in agreement with experiment, and show only very mild quark mass dependence. The second, RBC/UK, set of ensembles employs one strange and two degenerate (up and down) dynamical DWF quarks and Iwasaki gauge action. The strange quark mass is set at 0.04, and three up/down mass values of 0.03, 0.02 and 0.01 in lattice units are used. The lattice cutoff is about 1.6 GeV and the spatial volume is about (3.0 fm){sup 3}. Even with preliminary statistics of 25-30 gauge configurations, the ratios g{sub A}/g{sub V} and {sub u-d}/{sub {Delta} u - {Delta} d} are consistent with experiment and show only very mild quark mass dependence. Another structure function moment, d{sub 1}, though yet to be renormalized, appears small in both sets.

Huey-Wen Lin; Shigemi Ohta

2006-07-23

179

Review of nucleon-nucleon scattering experiments and many dinucleon resonances  

International Nuclear Information System (INIS)

Structures appearing in various experimental data (particularly those with polarized beams) in nucleon-nucleon systems are reviewed. A number of candidates are presented for dibaryon resonances which can couple to nucleon-nucleon systems

1980-01-01

180

Calculation of the pion-nucleon double spectral functions and applications  

International Nuclear Information System (INIS)

[en] In the present thesis the latest results from pion-pion and pion-nucleon phase analyses are applied in order to calculate the pion-nucleon double spectral functions which belong to the elastic unitarity in the t-channel. The equivalence of the partial wave projection of these spectral functions in the s-channel with the elastic t-channel unitarity is extensively discussed. After we summarize the aspects of the pion-nucleon system seeming in this connection interesting we discuss the Mandelstam method for the calculation of the spectral functions by means of the elastic t-channel unitarity as well as the applied input and present the results. Thereafter we use these results in order to calculate by means of a fixed t-channel dispersion relation the real parts of the t-channel cuts. Partial wave projections into the t-channel are proved as equivalent to the elastic t-channel unitarity. We study the compatibility of the asymptotic behaviour of the spectral functions relative to the energy with current Regge pole models. Finally we use our results in order to calculate the pion-nucleon partial waves by means of their Froissart-Gribov representations which follow from their analyticity at fixed energy. (orig./HSI)[de] In der vorliegenden Arbeit werden die neuesten Ergebnisse aus Pion-Pion und Pion-Nukleon Phasenanalysen verwendet, um die Pion-Nukleon Doppelspektralfunktionen zu berechnen, die zu elastischer Unitaritaet im t-Kanal gehoeren. Die Aequivalenz der Partialwellenprojektion dieser Spektralfunktionen in den s-Kanal mit der elastischen s-Kanal Unitaritaet wird ausfuehrlich diskutiert. Nachdem wir die in diesem Zusammenhang interessant erscheinenden Aspekte des Pion-Nukleon Streusystems zusammenfassen, diskutieren wir die Mandelstam-Methode zur Berechnung der Spektralfunktionen mit Hilfe der elastischen t-Kanal Unitaritaet sowie den verwendeten Input und stellen die Resultate vor. Danach benutzen wir die Ergebnisse, um mit Hilfe einer feste-t Dispersionsrelation die Realteile der t-Kanal Schnitte zu berechnen. Partialwellenprojektionen in den t-Kanal erweisen sich als aequivalent zur elastischen t-Kanal Unitaritaet. Wir untersuchen die Kompatibilitaet des asymptotischen Verhaltens der Spektralfunktionen bezueglich der Energie mit gaengigen Reggepol Modellen. Schliesslich benutzen wir unsere Ergebnisse, um die Pion-Nukleon Partialwellen mit Hilfe ihrer Froissart-Gribov Integral Darstellungen, die aus der Analytizitaet bei fester Energie folgen, zu berechnen. (orig./HSI)

1986-01-01

 
 
 
 
181

Nuclear versus nucleon structure effects on nuclear transparency  

Energy Technology Data Exchange (ETDEWEB)

Nuclear structure effects account for the observed enhancement of the nuclear transparency to moderate energy protons, with respect to the predictions of Glauber theory. This enhancement appears to be comparable to the one associated with the onset of color transparency in the Q2 range spanned by the available (e,e'p) data (Q2 < 7 (GeV/c)2). It is argued that in this kinematical regime a stronger colour transparency signal can be observed in the low energy loss tail of the inclusive electron-nucleus cross section, corresponding to large values of the Bjorken scaling variable x (x>2).

O. Benhar

1997-06-25

182

Structure Functions at Low Q2: Target Mass Corrections  

International Nuclear Information System (INIS)

[en] We discuss recent developments in the study of structure functions at low Q2, focusing in particular on the issue of target mass corrections (TMC) to nucleon structure functions. We summarize the standard TMC implementation, and contrast this with a new formulation which has the correct kinematic threshold behavior at finite Q2 in the x -> 1 limit

2007-06-03

183

Structure Functions at Low Q^2: Target Mass Corrections  

Energy Technology Data Exchange (ETDEWEB)

We discuss recent developments in the study of structure functions at low Q^2, focusing in particular on the issue of target mass corrections (TMC) to nucleon structure functions. We summarize the standard TMC implementation, and contrast this with a new formulation which has the correct kinematic threshold behavior at finite Q^2 in the x -> 1 limit.

Wally Melnitchouk

2007-05-30

184

Micro-review of structure functions and parton distribution functions  

International Nuclear Information System (INIS)

[en] There has recently been a great deal of discussion concerning the surprising differences in the measurements of the nucleon structure function F2(x,Q2), off of a hydrogen target, by the high statistics muoproduction experiments EMC and BCDMS. In this short review I will attempt to summarize the status of the experimental measurements of the structure functions and highlight any significant disagreements. At the conclusion I will comment on the status of the extraction of the parton distribution functions from these measurements. 17 refs., 16 figs., 2 tabs

1989-01-01

185

Nuclear energy density functional from chiral pion-nucleon dynamics revisited  

Science.gov (United States)

We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from 1?-exchange, iterated 1?-exchange, and irreducible 2?-exchange with intermediate ?-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass M?(?) entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength F(?) of the (? surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region ?/2nucleon interactions mediated by 2?-exchange with virtual ?-excitation (of the “correct sign”). In the region around ?/2?0.08 fm-3 where the spin-orbit interaction in nuclei gains most of its weight these two components tend to cancel, thus leaving all room for the short-range spin-orbit interaction. The strength function F(?) multiplying the square of the spin-orbit density comes out much larger than in phenomenological Skyrme forces and it has a pronounced density dependence.

Kaiser, N.; Weise, W.

2010-05-01

186

Recent observation of short range nucleon correlations in nuclei and their implications for the structure of nuclei and neutron stars  

CERN Multimedia

Novel processes probing the decay of nucleus after removal of a nucleon with momentum larger than Fermi momentum by hard probes finally proved unambiguously the evidence for long sought presence of short-range correlations (SRCs) in nuclei. In combination with the analysis of large Q^2, A(e,e')X processes at x>1 they allow us to conclude that (i) practically all nucleons with momenta larger than 300 MeV/c belong to SRCs, consisting mostly of two nucleons, ii) probability of such SRCs in medium and heavy nuclei is approximately 25%, iii) a fast removal of such nucleon practically always leads to emission of correlated nucleon with approximately opposite momentum, iv) proton removal from two-nucleon SRCs in 90% of cases is accompanied by a removal of a neutron and only in 10% by a removal of another proton. We explain that observed absolute probabilities and the isospin structure of two nucleon SRCs confirm the important role that tensor forces play in internucleon interactions. We find also that the presence o...

Frankfurt, Leonid; Strikman, Mark

2008-01-01

187

Role of diquarks inelastic structure functions  

Energy Technology Data Exchange (ETDEWEB)

It has been suggested that almost all the Q/sup 2/ dependence of nucleon structure functions can be understood in terms of quark (scaling) + diquark (approx. equal to 1/Q/sup 2/) contributions. We confront the simplest version of such a model with data from neutrino (high Q/sup 2/) as well as electron (low Q/sup 2/) experiments and find no overall consistent agreement.

Close, F.E.; Roberts, R.G.

1981-01-01

188

Nucleon-nucleon momentum correlation function as a probe of the density distribution of valence neutron in neutron-rich nucleus  

CERN Multimedia

Proton-neutron, neutron-neutron and proton-proton momentum correlation functions ($C_{pn}$, $C_{nn}$, $C_{pp}$) are systematically investigated for $^{15}$C and other C isotopes induced collisions at different entrance channel conditions within the framework of the isospin-dependent quantum molecular dynamics (IDQMD) model complemented by the CRAB (correlation after burner) computation code. $^{15}$C is a prime exotic nucleus candidate due to the weakly bound valence neutron coupling with closed-neutron shell nucleus $^{14}$C. In order to study density dependence of correlation function by removing the isospin effect, the initialized $^{15}$C projectiles are sampled from two kinds of density distribution from RMF model, in which the valence neutron of $^{15}$C is populated on both 1$d$5/2 and 2$s$1/2 states, respectively. The results show that the density distributions of valence neutron significantly influence nucleon-nucleon momentum correlation function at large impact parameter and high incident energy. T...

Cao, X G; Ma, Y G; Fang, D Q; Zhang, G Q; Guo, W; Chen, J G; Wang, J S; 10.1103/PhysRevC.86.044620

2012-01-01

189

One-nucleon removal reactions as a test of overlap functions from the one-body density matrix calculations  

International Nuclear Information System (INIS)

Overlap functions and spectroscopic factors extracted from a model one-body density matrix (OBDM) accounting for short-range nucleon-nucleon correlations are used to calculate differential cross sections of (p, d) reactions and the momentum distributions of transitions to single-particle states in 16O and 40Ca. A comparison between the experimental (p, d) and (e, e'p) data, their DWBA and CDWIA analyses and the OBDM calculations is made. Our theoretical predictions for the spectroscopic factors are compared with the empirically extracted ones. It is shown that the overlap functions obtained within the Jastrow correlation method are applicable to the description of the quantities considered. (author)

1997-01-01

190

New measurements of high-momentum nucleons and short-range structures in nuclei.  

UK PubMed Central (United Kingdom)

We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.

Fomin N; Arrington J; Asaturyan R; Benmokhtar F; Boeglin W; Bosted P; Bruell A; Bukhari MH; Christy ME; Chudakov E; Clasie B; Connell SH; Dalton MM; Daniel A; Day DB; Dutta D; Ent R; El Fassi L; Fenker H; Filippone BW; Garrow K; Gaskell D; Hill C; Holt RJ; Horn T; Jones MK; Jourdan J; Kalantarians N; Keppel CE; Kiselev D; Kotulla M; Lindgren R; Lung AF; Malace S; Markowitz P; McKee P; Meekins DG; Mkrtchyan H; Navasardyan T; Niculescu G; Opper AK; Perdrisat C; Potterveld DH; Punjabi V; Qian X; Reimer PE; Roche J; Rodriguez VM; Rondon O; Schulte E; Seely J; Segbefia E; Slifer K; Smith GR; Solvignon P; Tadevosyan V; Tajima S; Tang L; Testa G; Trojer R; Tvaskis V; Vulcan WF; Wasko C; Wesselmann FR; Wood SA; Wright J; Zheng X

2012-03-01

191

The ground and excited states structure of a few-nucleon system in Gaussian representation  

International Nuclear Information System (INIS)

Complete text of publication follows. For three- and four-body bound systems with strong interaction, cluster and 'halo'-type effects are studied. The energy spectrum and wave functions of three- and four-nucleon systems are calculated with high precision for various NN-interaction potentials of different form with the use of the Gaussian representation of the variational method. The Efimov effect region is studied. Realistic NN-interaction potentials are considered for complete study of the nuclei T, 3He, and 4He properties (1). Convergence of the method with respect to the basis dimension extension is analyzed. Procedures are proposed to optimize the variational basis in order to achieve high precision in calculations with minimum number of the basis components. Nucleon density distributions, formfactors, momentum distributions, and pair correlation functions are calculated with high accuracy both for the ground and possible excited states. Degree of clusterization of the ground and excited states is analyzed. The 'halo' effect is shown to take place in the systems of three and four strongly interacting particles in the excited states near the threshold. The above effect manifests itself in the density distribution as a long-range peripheral part of less intensity in comparison with the central core. In respective formfactors of the excited states, a specific additional dip of a finite value is revealed at small momentum transfers related to the long-range region. (author)

2000-01-01

192

Lepton nucleon scattering  

International Nuclear Information System (INIS)

The topic of lepton-nucleon inclusive scattering is reviewed. Some of the experiments providing data on these interactions are described first. Then the constituent model of the nucleon and the contribution of various types of experiments are discussed; data from the experiments are compared and some simple predictions of the quark model are covered. Next, some of the fundamental notions behind quantum chromodynamics (QCD) are presented. Subsequent sections examine detailed tests of QCD. These include the ratio of longitudinal to transverse photoabsorption cross sections, the proton form factor in elastic ep scattering, and the dependence of structure functions on Q2. In conclusion, all the tests of QCD are tabulated, and the results are evaluated. 32 references, 33 figures, 4 tables

1979-01-01

193

Structure functions of nuclei in the pion exchange model  

International Nuclear Information System (INIS)

A detailed derivation is presented of the fact that the deep inelastic structure function of a nucleus may be expressed directly in terms of the empirical structure functions of the constituent nucleons and mesons and the wave function of the nuclear bound state. The assumptions made are specified. The pion exchange model provides a unified quantitative description for all x of nuclear effects observed in deep inelastic scattering of charged and neutral leptons from nuclei. 9 refs., 1 fig

1985-01-01

194

New measurements of high-momentum nucleons and short-range structures in nuclei  

CERN Document Server

We present new, high-Q^2 measurements of inclusive electron scattering from high-momentum nucleons in nuclei. This yields an improved extraction of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data extend to the kinematic regime where three-nucleon correlations are expected to dominate and we observe significantly greater strength in this region than previous measurements.

Fomin, N; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Bukhari, M H S; Chudakov, E; Clasie, B; Connell, S H; Dalton, M M; Daniel, A; Day, D B; Dutta, D; Ent, R; Fassi, L El; Fenker, H; Filippone, B W; Garrow, K; Gaskell, D; Hill, C; Holt, R J; Horn, T; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, M; Lindgren, R; Lung, A F; Malace, S; Markowitz, P; McKee, P; Meekins, D G; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Seely, J; Segbefia, E; Slifer, K; Smith, G R; Solvignon, P; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Trojer, R; Tvaskis, V; Vulcan, W F; Wasko, C; Wesselmann, F R; Wood, S A; Wright, J; Zheng, X

2011-01-01

195

Phenomenological delineation of the quark-gluon structure from nucleon electromagnetic form factors  

Science.gov (United States)

We investigate a synthesis of topological chiral models with the vector meson dominance idea, with applications to nucleon and pion electromagnetic form factors. We suggest that the large tensor coupling of the ?-meson to the nucleon, about twice that given by the vector dominance model, is an indicator of quark-gluon substructure of the nucleon at distances Regensburg, D-8400 Regensburg, W. Germany; supported in part by Deutsche Forschungsgemeinschaft and by Bundesministerium für Forschung und Technologie.

Brown, G. E.; Rho, Mannque; Weise, W.

1986-06-01

196

The partonic structure of the nucleon from generalized transverse momentum-dependent parton distributions  

CERN Multimedia

We discuss the general formalism for the calculation in light-front quark models of the fully unintegrated, off-diagonal quark-quark correlator of the nucleon, parametrized in terms of generalized transverse momentum dependent parton distributions (GTMDs). By taking specific limits or projections, these GTMDs yield various transverse-momentum dependent and generalized parton distributions, thus providing a unified framework to simultaneously model different observables. The corresponding distributions in impact-parameter space are the Wigner functions which provide multidimensional images of the quark distributions in phase space. We present results within a light-front constituent quark model, discussing some of the complementary aspects encoded in the different distributions and the relation to the quark orbital angular momentum of the proton.

Pasquini, B

2013-01-01

197

On the role of diquarks in deep inelastic structure functions  

International Nuclear Information System (INIS)

It has been suggested that almost all the Q2 dependence of nucleon structure functions can be understood in terms of quark (scaling) + diquark (approximately 1/Q2) contributions. The simplest version of such a model is confronted here with data from neutrino (high Q2) as well as electron (low Q2) experiments and no overall consistent agreement is found. (author)

1980-01-01

198

Dynamical rescaling and universality of hadron structure functions  

Energy Technology Data Exchange (ETDEWEB)

We argue that pion and nucleon structure functions differ principally due to their different numbers of quarks and different scales of confinement. The former generates an x rescaling while the latter, in QCD, gives rise to a Q/sup 2/ rescaling.

Close, F.E.; Roberts, R.G.; Ross, G.G.

1984-07-19

199

Dynamical rescaling and universality of hadron structure functions  

International Nuclear Information System (INIS)

[en] We argue that pion and nucleon structure functions differ principally due to their different numbers of quarks and different scales of confinement. The former generates an x rescaling while the latter, in QCD, gives rise to a Q2 rescaling. (orig./WL)

1984-07-19

200

Dynamical Rescaling and Universality of Hadron Structure Functions.  

Science.gov (United States)

The authors argue that pion and nucleon structure functions differ principally due to their different numbers of quarks and different scales of confinement. The former generates an x rescaling while the latter, in QCD, gives rise to a (Q sup 2) rescaling....

F. E. Close R. G. Roberts G. G. Ross

1984-01-01

 
 
 
 
201

Treatment of Two Nucleons in Three Dimensions  

Directory of Open Access Journals (Sweden)

Full Text Available We extend a new treatment proposed for two-nucleon (2N) and three-nucleon (3N) bound states to 2N scattering. This technique takes momentum vectors as variables, thus, avoiding partial wave decomposition, and handles spin operators analytically. We apply the general operator structure of a nucleon-nucleon (NN) potential to the NN T-matrix, which becomes a sum of six terms, each term being scalar products of spin operators and momentum vectors multiplied with scalar functions of vector momenta. Inserting this expansions of the NN force and T-matrix into the Lippmann-Schwinger equation allows to remove the spin dependence by taking traces and yields a set of six coupled equations for the scalar functions found in the expansion of the T-matrix.

Fachruddin I.; Elster Ch.; Golak J.; Skibi?ski R.; Glöckle W.; Wita?a H.

2010-01-01

202

Polarized structure functions a theoretical update  

CERN Document Server

We review recent developments in the theory and phenomenology of polarized structure functions. We summarize recent experimental data on the proton and deuteron structure function g_1, and their impact on the understanding of polarized sum rules. Specifically, we discuss how accurate measurements of the singlet and nonsinglet first moment of g_1 test perturbative and nonperturbative QCD, and critically examine the way these measurements are arrived at. We then discuss how the extraction of structure functions from the data can be improved by means of a theoretical analysis of their x and Q^2 dependence, and how, conversely, experimental information on this dependence can be used to pin down the polarized parton content of the nucleon.

Forte, Stefano

1995-01-01

203

General Structure Functions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A general concept of a structure function is proposed by considering a general order topology, where possible degrees of performance for the system and its components are going to be represented. Finite multistate structure functions and continuum structures can therefore be viewed as particular cas...

Montero de Juan, Francisco Javier; Tejada Cazorla, Juan Antonio; Yáñez, J.

204

One-nucleon removal reactions as a test of overlap functions from the one-body density matrix calculations  

Energy Technology Data Exchange (ETDEWEB)

Overlap functions and spectroscopic factors extracted from a model one-body density matrix (OBDM) accounting for short-range nucleon-nucleon correlations are used to calculate differential cross sections of (p, d) reactions and the momentum distributions of transitions to single-particle states in {sup 16}O and {sup 40}Ca. A comparison between the experimental (p, d) and (e, e'p) data, their DWBA and CDWIA analyses and the OBDM calculations is made. Our theoretical predictions for the spectroscopic factors are compared with the empirically extracted ones. It is shown that the overlap functions obtained within the Jastrow correlation method are applicable to the description of the quantities considered. (author)

Dimitrova, S.S. [Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Nuclear Physics Laboratory, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Gaidarov, M.K. [Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Antonov, A.N. [Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Nuclear Physics Laboratory, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Stoitsov, M.V. [Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Hodgson, P.E [Nuclear Physics Laboratory, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Lukyanov, V.K.; Zemlyanaya, E.V. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Krumova, G.Z. [Department of Physics, University of Rousse, Rousse 7017 (Bulgaria)

1997-11-01

205

A nucleon in alpha condensate  

Energy Technology Data Exchange (ETDEWEB)

We propose a new treatment for the interaction between a nucleon and an {alpha}-condensate, which is described by THSR wave function in a fully microscopic way. In particular, the nucleon can be expected to clarify the property of {alpha}-condensate as its probe. We show that the treatment works well for the system of nucleon +3{alpha}{sup -} condensate.

Tohsaki, A [Research Centre for Nuclear Physics, Osaka University, Osaka, 567-0047 (Japan)], E-mail: tohsaki@rcnp.osaka-u.ac.jp

2008-05-15

206

A nucleon in alpha condensate  

International Nuclear Information System (INIS)

We propose a new treatment for the interaction between a nucleon and an ?-condensate, which is described by THSR wave function in a fully microscopic way. In particular, the nucleon can be expected to clarify the property of ?-condensate as its probe. We show that the treatment works well for the system of nucleon +3?- condensate.

2008-01-01

207

Photon structure function  

International Nuclear Information System (INIS)

Theoretical understanding of the photon structure function is reviewed. As an illustration of the pointlike component, the parton model is briefly discussed. However, the systematic study of the photon structure function is presented through the framework of the operator product expansion. Perturbative QCD is used as the theoretical basis for the calculation of leading contributions to the operator product expansion. The influence of higher order QCD effects on these results is discussed. Recent results for the polarized structure functions are discussed.

1980-01-01

208

Inelastic nucleon-nucleon channels  

International Nuclear Information System (INIS)

This paper presents the interest of inelastic nucleon-nucleon channels, more particularly the NN ? NN ? channels, pointing out the experimental aspects. Saturne possibilities are examined in this field. 43 refs

1986-01-01

209

Proton and neutron structure functions in a Fermi-gas approximation  

International Nuclear Information System (INIS)

The proton and neutron deep-inelastic scattering structure functions are found to be fit reasonably well by a finite-temperature Fermi-gas (effective) description of the confined quarks. Support problems at negative x are avoided completely and formal sum rules are satisfied. The characteristic difference between the u and d valence distributions, which is difficult to achieve in many models of nucleon structure, arises naturally as a consequence of the different densities of u and d quarks in the nucleon

1990-12-01

210

Proton and neutron structure functions in a Fermi-gas approximation  

Science.gov (United States)

The proton and neutron deep-inelastic scattering structure functions are found to be fit reasonably well by a finite-temperature Fermi-gas (effective) description of the confined quarks. Support problems at negative x are avoided completely and formal sum rules are satisfied. The characteristic difference between the u and d valence distributions, which is difficult to achieve in many models of nucleon structure, arises naturally as a consequence of the different densities of u and d quarks in the nucleon.

Bickerstaff, R. P.; Londergan, J. T.

1990-12-01

211

Comments on pseudoscalar-nucleon coupling  

International Nuclear Information System (INIS)

[en] In the light of the recent EMC measurement of polarized muon-proton scattering we reexamine the coupling of the pseudoscalar Higgs boson to nucleons in a class of spontaneous CP-violation models where CP-violation can arise from the scalar-pseudoscalar Higgs boson mixings mechanism. Previous naive estimates of the effective direct Higgs-nucleon coupling can be reduced by taking into account the EMC data on the spin-dependent structure function. We show that this coupling can be consistent with being zero. This implies that the electric dipole moment of neutron induced by this Higgs-nucleon coupling in these models may vanish instead of dominating over the other contributions. Remarks on axion-nucleon coupling are also given

1989-01-01

212

Probing The Standard Model And Nucleon Structure Via Parity-violating Electron Scattering  

CERN Document Server

Parity-violating electron scattering has developed over the last 25 years into a tool to study both the structure of electroweak interactions and the structure of nucleons. This thesis reports work on two parity- violation experiments, the Hall A Proton Parity Experiment (HAPPEX) and SLAC E-158. HAPPEX (Jefferson Laboratory, 1998–1999) measured the parity-violating asymmetry in elastic e- p scattering at Q2 = 0.477 GeV2. This asymmetry is sensitive to the proton's strange elastic form factors. An asymmetry of ALR = ?15.05 ± 0.98(stat) ± 0.56(syst) ppm was measured. This asymmetry measurement allowed HAPPEX to set new constraints on the strange elastic form factors of the proton: GEs+0.392G Ms=0.025 ±0.20± 0.014, where GEs and GMs are the strange electric and magnetic form factors of the proton, respectively. The first error is the quadrature sum of the experimental errors and the second error is due to uncertainty in electromagnetic form fact...

Humensky, T B

2003-01-01

213

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)

2001-01-01

214

In-medium nucleon-nucleon potentials in configuration space  

Energy Technology Data Exchange (ETDEWEB)

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)

Beyer, M.; Sofianos, S.A. [Physics Department, University of South Africa, Pretoria (South Africa)

2001-10-01

215

Spin structure of the nucleon from the lp-DIS with charged weak current  

International Nuclear Information System (INIS)

The possibilities of determination of quark contributions to the nucleon spin based on observable asymmetries of lp-semi-inclusive deep inelastic scattering with the charged weak current of the p-, K-meson production are considered. (authors)

2010-01-01

216

Variational calculations with correlated basis functions: Three-nucleon and three-alpha-particle systems  

Energy Technology Data Exchange (ETDEWEB)

A new variational method is applied to the solution of the Schroedinger equation for interacting few-body systems. The results for three nucleons interacting via the spin-dependent Malfliet-Tjon potential and three alpha particles interacting via the Ali-Bodmer potential are presented and compared with Faddeev and ATMS results, respectively.

Atti, C.C.D.; Simula, S.

1985-09-01

217

Deuteron Spin Structure Functions in the Resonance and DIS Regions  

Energy Technology Data Exchange (ETDEWEB)

We derive relations between spin-dependent nuclear and nucleon g_1 and g_2 structure functions, valid at all Q^2, and in both the resonance and deep inelastic regions. We apply the formalism to the specific case of the deuteron, which is often used as a source of neutron structure information, and compare the size of the nuclear corrections calculated using exact kinematics and using approximations applicable at large Q^2.

S. Kulagin; W. Melnitchouk

2007-10-03

218

Purely Functional Structured Programming  

CERN Multimedia

The idea of functional programming has played a big role in shaping today's landscape of mainstream programming languages. Another concept that dominates the current programming style is Dijkstra's structured programming. Both concepts have been successfully married, for example in the programming language Scala. This paper proposes how the same can be achieved for structured programming and PURELY functional programming via the notion of LINEAR SCOPE. One advantage of this proposal is that mainstream programmers can reap the benefits of purely functional programming like easily exploitable parallelism while using familiar structured programming syntax and without knowing concepts like monads. A second advantage is that professional purely functional programmers can often avoid hard to read functional code by using structured programming syntax that is often easier to parse mentally.

Obua, Steven

2010-01-01

219

Experimental studies of the quark-gluon structure of nucleons and nuclei and of pion- and proton-nucleus interactions. Progress report, April 1, 1994--March 31, 1997  

International Nuclear Information System (INIS)

This report summarizes the work on experimental research in intermediate energy nuclear physics carried out by New Mexico State University from April 1, 1994, through March 31, 1996 under a grant from the US Department of Energy. During this period we began phasing out our programs of study of pion-nucleus and pion-nucleon interaction and of nucleon-nucleus charge-exchange reactions, which have been our major focus of the past two or three years. At the same time we continued moving in a new direction of research on studies of the internal structure of nucleons and nuclei in terms of quarks and gluons. The pion and nucleon work has been aimed at improving our understanding of the nature of pion and proton interactions in the nuclear medium and of various aspects of nuclear structure. The studies of the quark-gluon structure of nucleons are aimed at clarifying such problems as the nature of the quark sea and the relation of the nucleon spin to the spins of the quarks within the nucleon, questions which are of a very fundamental nature.

1996-01-01

220

Experimental studies of the quark-gluon structure of nucleons and nuclei and of pion- and proton-nucleus interactions. Progress report, April 1, 1994--March 31, 1997  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the work on experimental research in intermediate energy nuclear physics carried out by New Mexico State University from April 1, 1994, through March 31, 1996 under a grant from the US Department of Energy. During this period we began phasing out our programs of study of pion-nucleus and pion-nucleon interaction and of nucleon-nucleus charge-exchange reactions, which have been our major focus of the past two or three years. At the same time we continued moving in a new direction of research on studies of the internal structure of nucleons and nuclei in terms of quarks and gluons. The pion and nucleon work has been aimed at improving our understanding of the nature of pion and proton interactions in the nuclear medium and of various aspects of nuclear structure. The studies of the quark-gluon structure of nucleons are aimed at clarifying such problems as the nature of the quark sea and the relation of the nucleon spin to the spins of the quarks within the nucleon, questions which are of a very fundamental nature.

NONE

1996-10-01

 
 
 
 
221

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, ?N scattering and the ?-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

1991-01-01

222

Nucleon elastic form factors  

Energy Technology Data Exchange (ETDEWEB)

The nucleon form factors are still the subject of active investigation even after an experimental effort spanning 50 years. This is because they are of critical importance to our understanding of the electromagnetic properties of nuclei and provide a unique testing ground for QCD motivated models of nucleon structure. Progress in polarized beams, polarized targets and recoil polarimetry have allowed an important and precise set of data to be collected over the last decade. I will review the experimental status of elastic electron scattering from the nucleon along with an outlook for future progress.

D. Day

2007-03-01

223

Phenomenology of Deep Inelastic Scattering Structure Functions  

UK PubMed Central (United Kingdom)

I review recent progress in global analysis of deep inelastic scatteringstructure functions. The new ingredients are recent experimental data andattempts to incorporate heavy quarks in a consistent way. A new technique forincluding the resummation of large log 1=x terms is discussed.INTRODUCTIONSince we met in Rome last year significant progress has been achieved inthe understanding of deep inelastic scattering (DIS) structure functions andthe implications of new measurements on global analyses and the extractionof parton distribution functions (pdf's). Firstly, two major experiments Gammathe muon-nucleon collaboration NMC at CERN and the neutrino-iron collaborationCCFR at Fermilab have presented updated results. The NMCcollaboration [1] reported their final numbers for F 2 for both proton and deuteriumtargets at 90, 120, 200 and 280 GeV. The CCFR [2] collaborationimplemented a new energy calibration in their analysis. The latter give agreater value of ff s (MZ ) tha...

R. G. Roberts

224

Heretical structure functions  

Energy Technology Data Exchange (ETDEWEB)

In this talk I describe an approach to the hadronic structure functions which is different from the ordinary one. In our approach an inelastic leptoproduction event corresponds to a measuring process. (orig./HSI).

Andersson, B. (Dept. of Theoretical Physics, Lund Univ. (Sweden))

1992-12-01

225

Heretical structure functions  

International Nuclear Information System (INIS)

[en] In this talk I describe an approach to the hadronic structure functions which is different from the ordinary one. In our approach an inelastic leptoproduction event corresponds to a measuring process. (orig./HSI)

1992-01-01

226

Introduction to structure functions  

Energy Technology Data Exchange (ETDEWEB)

The theory of deep inelastic scattering structure functions is reviewed with an emphasis put on the QCD expectations of their behaviour in the region of small values of Bjorken parameter x. (author). 56 refs.

Kwiecinski, J. [Institute of Nuclear Physics, Cracow (Poland)

1996-07-01

227

Structure function monitor  

Energy Technology Data Exchange (ETDEWEB)

Methods and apparatus for a structure function monitor provide for generation of parameters characterizing a refractive medium. In an embodiment, a structure function monitor acquires images of a pupil plane and an image plane and, from these images, retrieves the phase over an aperture, unwraps the retrieved phase, and analyzes the unwrapped retrieved phase. In an embodiment, analysis yields atmospheric parameters measured at spatial scales from zero to the diameter of a telescope used to collect light from a source.

McGraw, John T. (Placitas, NM); Zimmer, Peter C. (Albuquerque, NM); Ackermann, Mark R. (Albuquerque, NM)

2012-01-24

228

Nucleon-nucleon collision profile and cross section fluctuations  

CERN Document Server

The nucleon-nucleon collision profile, being the basic entity of the wounded nucleon model, is usually adopted in the form of hard sphere or the Gaussian shape. We suggest that the cross section fluctuations given by the gamma distribution leads to the profile function which smoothly ranges between the both limiting forms. Examples demonstrating sensitivity of profile function on cross section fluctuations are discussed.

Rybczynski, Maciej

2013-01-01

229

On the unabridged 7D-folding structure of the optical model potential for nucleon-nucleus scattering  

Directory of Open Access Journals (Sweden)

Full Text Available Microscopic optical model potentials for nucleon-nucleus collisions, based on density-dependent effective interactions, involve multi-dimensional integrals to account for the Fermi motion of the bound nucleons of the target. If a spherical matter distribution is assumed, each matrix element of the optical potential in momentum space requires the evaluation of seven-dimensional integrals. Here we describe the structure of these potentials and report results from their actual evaluation. Results for the scattering observables are compared with those based on alternative approximations, observing moderate sensitivity. These findings validate the use of simpler expressions to evaluate folding optical potentials, from which higher-order or unconventional effects in the effective interaction can safely be investigated.

Arellano H.F.; Bauge E.

2012-01-01

230

Alternating-phase focusing accelerating structure for the argon ion acceleration up to 1 MeV/nucleon  

International Nuclear Information System (INIS)

Problems of developing accelerating-focusing channel for argon ion linac designed for film irradiation to produce nuclear filters are considered. Acceleration is supposed to be realized in two stages. At the first stage Ar ions are accelerated up to 0.5 MeV/nucleon in the 4 m long section. Then ion stripping up to equilibrium +7 charge and additional acceleration of charge spectrum up to 1 MeV/nucleon in the 1.3 m long section are performed. Data of numerical calculations of the main parameters of a channel with alternating-phase focusing and results of full-scale simulation of the accelerating structure at 25 MHz frequency performed on the base of double-wire line loaded with drift tubes are presented. 3 refs.; 2 figs

1989-01-01

231

Global study of nuclear structure functions  

International Nuclear Information System (INIS)

We present the results of a phenomenological study of unpolarized nuclear structure functions for a wide kinematical region of x and Q2. As a basis of our phenomenology we develop a model which takes into account a number of different nuclear effects including nuclear shadowing, Fermi motion and binding, nuclear pion excess and off-shell correction to bound nucleon structure functions. Within this approach we perform a statistical analysis of available data on the ratio of the nuclear structure functions F2 for different nuclei in the range from the deuteron to the lead. We express the off-shell effect and the effective scattering amplitude describing nuclear shadowing in terms of few parameters which are common to all nuclei and have a clear physical interpretation. The parameters are then extracted from statistical analysis of data. As a result, we obtain an excellent overall agreement between our calculations and data in the entire kinematical region of x and Q2. We discuss a number of applications of our model which include the calculation of the deuteron structure functions, nuclear valence and sea quark distributions and nuclear structure functions for neutrino charged-current scattering.

2006-01-23

232

Measurement of the Strange Quark Contribution to Nucleon Structure Through Parity-Violating Electron Scattering  

Energy Technology Data Exchange (ETDEWEB)

The G0 backward angle experiment, completed in Hall C of the Thomas Jefferson National Accelerator Facility (TJNAF), measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q2 = 0.22 and 0.63 (GeV/c)2. The asymmetries are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of lte 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. This was also the first measurement of the anapole moment effects in the axial-vector current at these four-momentum transfers.

Colleen Ellis

2010-07-01

233

Chiral-Odd Structure Function $h_1^D(x)$ and Tensor Charge of the Deuteron  

CERN Multimedia

The chiral-odd structure function h_{1}^D(x) and the tensor charge of the deuteron are studied within the Bethe-Salpeter formalism for the deuteron amplitude. Utilizing a simple model for the nucleon structure function, h_1^N, h_1^D(x) is calculated and the nuclear effects are analyzed.

Umnikov, A Yu; Khanna, F C; He, Han-xin

1996-01-01

234

What can be learned about meson nucleon interactions and nuclear structure from K+ total cross sections  

International Nuclear Information System (INIS)

K+ total cross sections on deuterium, 6Li, 12C, 28Si and 40Ca have been measured at four momenta in the range of 480--714 MeV/c. This study has revealed important modifications of the free-space K+-nucleon interaction when the nucleon is embedded in a nucleus. Some of the suggested modifications include unconventional nuclear medium effects such as partial quark deconfinement, mass rescaling of nuclear pionic fields or pion excess in nuclei and meson exchange currents

1993-01-01

235

Electromagnetic Structure and Reactions of Few-Nucleon Systems in ?EFT  

Directory of Open Access Journals (Sweden)

Full Text Available We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral e?ective ?eld theory (?EFT). The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and thermal neutron captures on p, d, and 3He.

Girlanda L.; Pastore S.; Schiavilla R.; Viviani M.

2010-01-01

236

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.

1992-01-01

237

A Variational Study of the Nucleon Wavefunction  

CERN Document Server

The structure of the nucleon is studied variationally on the lattice by maximizing the overlap between the nucleon and a trial function generated by an interpolating field containing variational parameters. We examine the effect of the spatial extent of smeared quark sources, the degree of gauge field smearing, the positions of smeared quark sources, inclusion of lower Dirac components and of diquark substructure. Exploratory calculations with quenched Wilson fermions at a pion mass of 900 MeV achieved overlaps as high as 80%, and there was no evidence of diquark substructure.

Bratt, J

2008-01-01

238

Three-nucleon bound state with isobaric and pionic degrees of freedom  

Energy Technology Data Exchange (ETDEWEB)

Wave function components containing a single ..delta..-isobar are included in the calculation of the three-nucleon bound states. The two-nucleon interaction acts in all partial waves up to total angular momentum I=2. The presence of a ..delta..-isobar increases the three-nucleon binding energy by about 0.3 MeV, 0.6 MeV repulsion being a dispersive two-body effect, 0.9 MeV attraction arising from the three-nucleon force with intermediate ..delta..-isobar. The effect of the ..delta.. on the three-nucleon charge and magnetic form factors is investigated. The possibility of treating the ..delta..-isobar as a dynamic pion-nucleon system in nuclear structure and nuclear-structure corrections beyond single ..delta.. excitation in the coupled channel approach are also discussed.

Sauer, P.U. (Hannover Univ. (Germany, F.R.). Inst. fuer Theoretische Physik)

1983-07-21

239

Correlated nucleons in configuration space  

International Nuclear Information System (INIS)

Several recent studies have dealt with the effects of short-range correlations on the momentum distribution of nucleons in nuclei. Here we investigate the correlation effects on the density and spectral distribution in coordinate space. A combination of experimental data and spectral functions calculated from realistic nucleon-nucleon interactions allows us to resolve a recently uncovered discrepancy with occupation of quasiparticle states derived from (e,e'p) data.

2004-01-01

240

Holographic Nucleons  

CERN Document Server

Recent developments in holography have provided a new vista to the nucleon composition. A strongly coupled core nucleon tied with vector mesons emerge in line with the Cheshire cat principle. The cat is found to hide in the holographic direction. We discuss the one, two and many baryon problem in this context and point at the striking similarities between the holographic results and recent lattice simulations at strong coupling.

Zahed, Ismail

2010-01-01

 
 
 
 
241

Spin and angular momentum in the nucleon  

Energy Technology Data Exchange (ETDEWEB)

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.

Franz Gross, Gilberto Ramalho, Teresa Pena

2012-05-01

242

Coupling of unpaired nucleons and collective band level structure in odd-odd nuclei  

International Nuclear Information System (INIS)

[en] The phenomenological approximation can be used for calculation energies of collective bands in odd-odd nuclei based on conflicting state of unpaired nucleons. The rule of decoupled particle as a spectator have been deduced. This mean that the energy spacing of collective bands in odd-odd nuclei are similar for energy spacing of collective bands based on state of coupled particle in adjacent odd nuclei. 44 refs.; 8 figs.; 2 tabs

1989-01-01

243

Nucleon structure with pion mass down to 149 MeV  

CERN Document Server

We present isovector nucleon observables: the axial, tensor, and scalar charges and the Dirac radius. Using the BMW clover-improved Wilson action and pion masses as low as 149 MeV, we achieve good control over chiral extrapolation to the physical point. Our analysis is done using three different source-sink separations in order to identify excited-state effects, and we make use of the summation method to reduce their size.

Green, Jeremy; Krieg, Stefan; Negele, John; Pochinsky, Andrew; Syritsyn, Sergey

2012-01-01

244

Nucleon structure in the Generalized Skyrme Model with explicit scalar dilaton-quarkonium meson  

International Nuclear Information System (INIS)

Static properties and electromagnetic form factors of nucleons are calculated in the Generalized Skyrme Model with an explicit scalar dilaton-quarkonium meson which saturates the quark-loop contribution to the scale anomaly of QCD. It is argued that the 0++ glueball-dilaton field cannot interact directly with the chiral field, but only through coupling with the dilaton-quarkonium meson. (author). 25 refs, 5 figs, 1 tab

1992-01-01

245

Charge structure of the hadronic final state in deep-inelastic muon-nucleon scattering  

International Nuclear Information System (INIS)

The general charge properties of the hadronic final state produced in ?+p and ?+d interactions at 280 GeV are investigated. Quark charge retention and local charge compensation is observed. The ratio F2n/F2p of the neutron to proton structure function is derived from the measurement of the average hadronic charge in ?d interactions. (orig.).

1988-01-01

246

Optimized chiral nucleon-nucleon interaction at next-to-next-to-leading order.  

UK PubMed Central (United Kingdom)

We optimize the nucleon-nucleon interaction from chiral effective field theory at next-to-next-to-leading order (NNLO). The resulting new chiral force NNLO(opt) yields ?(2)?1 per degree of freedom for laboratory energies below approximately 125 MeV. In the A=3, 4 nucleon systems, the contributions of three-nucleon forces are smaller than for previous parametrizations of chiral interactions. We use NNLO(opt) to study properties of key nuclei and neutron matter, and we demonstrate that many aspects of nuclear structure can be understood in terms of this nucleon-nucleon interaction, without explicitly invoking three-nucleon forces.

Ekström A; Baardsen G; Forssén C; Hagen G; Hjorth-Jensen M; Jansen GR; Machleidt R; Nazarewicz W; Papenbrock T; Sarich J; Wild SM

2013-05-01

247

An optimized chiral nucleon-nucleon interaction at next-to-next-to-leading order  

CERN Document Server

We optimize the nucleon-nucleon interaction from chiral effective field theory at next-to-next- to-leading order. The resulting new chiral force NNLOopt yields \\chi^2 \\approx 1 per degree of freedom for laboratory energies below approximately 125 MeV. In the A = 3, 4 nucleon systems, the contributions of three-nucleon forces are smaller than for previous parametrizations of chiral interactions. We use NNLOopt to study properties of key nuclei and neutron matter, and demonstrate that many aspects of nuclear structure can be understood in terms of this nucleon-nucleon interaction, without explicitly invoking three-nucleon forces.

Ekström, A; Forssén, C; Hagen, G; Hjorth-Jensen, M; Jansen, G R; Machleidt, R; Nazarewicz, W; Papenbrock, T; Sarich, J; Wild, S M

2013-01-01

248

Hard probes of short-range nucleon-nucleon correlations  

Energy Technology Data Exchange (ETDEWEB)

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.

J. Arrington, D. W. Higinbotham, G. Rosner, M. Sargsian

2012-10-01

249

Tests of Duality in the Spin-Structure Function g1  

International Nuclear Information System (INIS)

Although quark-hadron duality is well established for the spin-independent structure function, F2p, hardly any information is available on the low Q2 scaling behavior of spin-structure functions. Recent experiments at Jefferson Lab measured the spin-structure function g1 in the nucleon resonance region for variety of targets. Global and local duality was observed for Q2 values above ? 2 (GeV/c)2.

2006-11-17

250

Tests of Duality in the Spin-Structure Function g_1  

Energy Technology Data Exchange (ETDEWEB)

Although quark-hadron duality is well established for the spin-independent structure function, F{sub 2}{sup p}, hardly any information is available on the low Q{sup 2} scaling behavior of spin-structure functions. Recent experiments at Jefferson Lab measured the spin-structure function g1 in the nucleon resonance region for variety of targets. Global and local duality was observed for Q{sup 2} values above {approx} 2 (GeV/c){sup 2}.

Wolfgang Korsch

2006-11-01

251

The effect of confinement size on nuclear structure functions  

International Nuclear Information System (INIS)

The differences in the structure function of a heavy nucleus, such as iron, compared to a light nucleus, are considered. In the context of QCD, a suggestion that these differences arise as a result of differences in the scale of confinement of the nuclear constituents is investigated. This results in a simple relationship between heavy and light nucleus structure functions which is in reasonable agreement with experiment if the confinement size in iron is around 10-20% greater than in a free nucleon. (author).

1983-01-01

252

Nuclear effects and higher twists in $F_{3}$ structure function  

CERN Multimedia

We analyze the CCFR collaboration iron target data on the xF3 structure function making particular emphasis on the extraction of the higher twist contributions from data. Corrections for nuclear effects are applied in order to extract data on the structure function of the isoscalar nucleon. Our analysis confirms the observation made earlier, that the higher twist terms depend strongly on the level to which QCD perturbation theory analysis is applied. We discuss the impact of nuclear effects on the higher twist term as well as on the QCD scale parameter Lambda_{\\bar{MS}} extracted from the fit to data.

Kulagin, S A

2000-01-01

253

Deep inelastic structure functions: Decisive tests of QCD  

International Nuclear Information System (INIS)

[en] The purpose of this talk is to discuss the present status of scaling violations in deep inelastic lepton-nucleon scattering processes. Specifically, I will discuss in great detail which experimentally measured structure functions (or moments thereof) have to be used in order to discriminate between various field theories of the strong interactions such as (non-abelian) QCD, abelian vector-gluon, non-abelian scalar-gluon, and abelian scalar-gluon theories. Moreover I will delineate the sensitivity of certain structure functions to the fundamental couplings of the theory. (orig./WL)

1979-01-01

254

Range of the nucleon-nucleon effective interaction  

International Nuclear Information System (INIS)

[en] The experimentally known two-body matrix elements of the nucleon-nucleon interaction were used to check the sensitivity of these matrix elements to the effective nuclear interaction range. No significant dependence of the quality of fit as a function of range has been found. (author)

1997-01-01

255

Measurement of the spin structure function GP1 (X, Q2) with CLAS at Jefferson Lab  

International Nuclear Information System (INIS)

Inelastic scattering using polarized nucleon targets and polarized charged lepton beams allows the extraction of the structure functions g1 and g2 which provide information on the spin structure of the nucleon. A program designed to study such processes has been underway in Jefferson Lab since 1998. A polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the desired data. The measurements cover the resonance region with unprecedented detail and add significantly to the DIS data set at low to moderate Q2 and moderate to high x. The measured electron asymmetries are analyzed to produce quantities of interest, such as the photon-nucleon asymmetry AP1+, the spin structure function gP1 and its first moment Gamma1.

2005-01-01

256

Nucleon Strangeness and Unitarity  

UK PubMed Central (United Kingdom)

The strange-quark vector current form factors of the nucleon are analyzedwithin the framework of dispersion relations. Particular attention is paid tocontributions made by KK intermediate states to the form factor spectralfunctions. It is shown that, when the KK ! NN amplitude is evaluated inthe Born approximation, the KK contributions are identical to those arisingfrom a one-loop calculation and entail a serious violation of unitarity. Themean square strangeness radius and magnetic moment are evaluated by imposingunitarity bounds on the kaon-nucleon partial wave amplitudes. Theimpact of including the kaon's strangeness vector current form factor in thedispersion integrals is also evaluated.11.55.Fv, 12.38.Lg, 14.20.Dh, 14.65.BtTypeset using REVT E XNational Science Foundation Young Investigator1I. INTRODUCTIONThe low-energy structure of the nucleon's ss sea has become a topic of serious studyin the hadron structure community [1]. While deep inelast...

M. J. Musolf; H. -w. Hammer

257

Axial structure of the nucleon in a three-flavor chiral quark-meson model  

International Nuclear Information System (INIS)

Nucleon matrix elements of the 0, 3 and 8 flavor components of the axial current are calculated in an SU(3)L x SU(3)R chiral quark-meson model. An extension of the Gell-Mann-Levy lagrangian with effects of meson mixing is used. The cranking projection method is applied. The results are consistent with the recent EMC experiment, reinterpreted by taking into account non-perturbative effects. In particular, I find a sizable value of the flavor singlet axial current matrix element and a negligible contribution of the ss-bar components. 36 refs., 3 figs., 3 tabs. (author).

1989-01-01

258

Nuclear energy density functional from chiral pion-nucleon dynamics: Isovector terms  

Science.gov (United States)

We extend a recent calculation of the nuclear energy density functional in the framework of chiral perturbation theory by computing the isovector surface and spin-orbit terms: (?c nabla ? _p - ?c nabla ? _n )2 G d( ?) + (?c nabla ? _p - ?c nabla ? _n ·(?c J_p - ?c J_n ) G so( ?) + (?c J_p - ?c J_n )2 G J( ?) pertaining to different proton and neutron densities. Our calculation treats systematically the effects from 1 ? -exchange, iterated 1 ? -exchange, and irreducible 2 ? -exchange with intermediate ? -isobar excitations, including Pauli-blocking corrections up to three-loop order. Using an improved density-matrix expansion, we obtain results for the strength functions G d( ?) , G so( ?) and G J( ?) which are considerably larger than those of phenomenological Skyrme forces. These (parameter-free) predictions for the strength of the isovector surface and spin-orbit terms as provided by the long-range pion-exchange dynamics in the nuclear medium should be examined in nuclear structure calculations at large neutron excess.

Kaiser, N.

2010-07-01

259

Nucleon decay  

International Nuclear Information System (INIS)

[en] The significance of the nucleon decay in grand unified theories is described. Experimental methods and large existing apparatus are briefly described. Last limits are given for separate decay modes, and possible developments of experiments are discussed. 5 refs[fr] Les implications de la desintegration du nucleon sont decrites dans le cadre des theories grand-unifiees. Les methodes experimentales de detection et les grands appareillages existants sont brievement decrits. Les dernieres limites sont donnees en fonction du mode de desintegration recherche, et le developpement possible des recherches experimentales est evoque. 5 refs.

1983-01-01

260

Nuclear Effects On The Spin-Dependent Structure Functions  

UK PubMed Central (United Kingdom)

We address the question how the spin-dependent nucleon structure functiong 1 (x; Q2) gets modified when the nucleon is bound inside a nucleus. The modelknown to describe the unpolarized nuclear effects at moderate Bjorken x (x0:1) is extended to the polarized case. The results for the neutron in3He andthe proton in3H,7Li and19F are presented, showing significant changes inthe parton spin distributions and their moments. Scattering processes offpolarized7Li are suggested which could justify these theoretical calculationsand shed more light on both nuclear spin structure and short distance QCD.Work supported by the J. William Fulbright Commission and the Volkswagen Foundation.yPermanent address.The influence of nuclear effects on the nucleon structure functions received enormousinterest after the measurement by the European Muon Collaboration [1] of the ratio:RA(x; Q2) =1AFA2 (x; Q2)12FD2 (x; Q2)(1)for A=...

Jerzy Szwed

 
 
 
 
261

Do nucleons dissolve  

International Nuclear Information System (INIS)

A model is presented which describes multiquark, nuclear-like systems in a manner consistent with QCD, and with nuclear properties. Within the model, it is found that quasi-nucleon structures describe the minimum energy state of the system. This result is due to a balance between quarks lowering their kinetic energy by spreading out through the system, and lowering their color-magnetic spin-spin interaction energy by forming nucleon-like clusters. A strong core repulsion is evident, as is a realistic dip in the central matter density of the 4He-like, 12-quark system. 4 refs., 5 figs.

1985-01-01

262

Investigation of nuclear structure function and angular distribution of scattered leptons from 40Ca and 56Fe nuclei  

Directory of Open Access Journals (Sweden)

Full Text Available  In this paper, we calculate nuclear structure function and EMC effect of 40Ca and 56Fe nuclei. To achive the goals, we consider Fermi motion and binding energy contrbiution in the harmonic oscillator model. In this model, harmonic oscillator parameter ?? related to shells root mean square radius and for free nucleon structure functions, is obtained from GRV’s free nucleon structure functions. Then, we calculate differential cross section of lepton scattering from those nuclei at the E=4.8 GeV and E=4.032 GeV. The obtained results show good agreement with available experimental data.

MH Mosavi; M Jedi Chorvadeh; F Zolfagharpour

2012-01-01

263

Relativistic nucleon-nucleon potentials  

International Nuclear Information System (INIS)

[en] A method for fitting relativistic nucleon-nucleon (NN) potentials to phase-shift data has been developed and is being used to construct a relativistic version of the Argonne v14 potential. This has been achieved by combining existing momentum-space (MS) and configuration-space (CS) computer codes for NN scattering. The MS code is required to solve the relativistic Schroedinger equation, while the CS code is much more efficient in searching for potential parameters to fit the data

1984-04-01

264

Nuclear medium modification of the F2 structure function  

CERN Multimedia

We study the nuclear effects in the electromagnetic structure function $F_{2}(x, Q^2)$ in nuclei in the deep inelastic lepton nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. The ratios $R_{F2}^A(x,Q^2)=\\frac{2F_2^A(x,Q^2)}{AF_{2}^{Deut}(x,Q^2)}$ are obtained and compared with the recent JLAB results for light nuclei that show a non trivial A dependence.

Athar, M Sajjad; Vacas, M J Vicente

2009-01-01

265

Exploring Three Nucleon Forces in Lattice QCD  

CERN Multimedia

We study the three nucleon force in Nf=2 dynamical clover fermion lattice QCD, utilizing the Nambu-Bethe-Salpeter wave function of the three nucleon system. Since parity-odd two nucleon potentials are not available in lattice QCD at this moment, we develop a new formulation to extract the genuine three nucleon force which requires only the information of parity-even two nucleon potentials. In order to handle the extremely expensive calculation cost, we consider a specific three-dimensional coordinate configuration for the three nucleons. We find that the linear setup is advantageous, where nucleons are aligned linearly with equal spacings. The lattice calculation is performed with 16^3 x 32 configurations at \\beta=1.95, m_\\pi=1.13 GeV generated by CP-PACS Collaboration, and the result of the three nucleon force in triton channel is presented.

Doi, Takumi

2011-01-01

266

DNA: Structure and function  

DEFF Research Database (Denmark)

This chapter discusses the structure and function of DNA. DNA occupies a critical role in cells, because it is the source of all intrinsic genetic information. Chemically, DNA is a very stable molecule, a characteristic important for a macromolecule that may have to persist in an intact form for a long period of time before its information is accessed by the cell. Although DNA plays a critical role as an informational storage molecule, it is by no means as unexciting as a computer tape or disk drive. The structure of the DNA described by Watson and Crick in 1953 is a right handed helix of two individual antiparallel DNA strands. Hydrogen bonds provide specificity that allows pairing between the complementary bases (A.T and G.C) in opposite strands. Base stacking occurs near the center of the DNA helix and provides a great deal of stability to the helix (in addition to hydrogen bonding). The sugar and phosphate groups form a “backbone” on the outside of the helix. There are about 10 base pairs (bp) per turn ofthe double helix.

Sinden, Richard R.; E. Pearson, Christopher

1998-01-01

267

LAMPF Nucleon-Nucleon Program  

Energy Technology Data Exchange (ETDEWEB)

NN activities at LAMPF are summarized. Measurements with p+p are now focusing on inelastic spin transfer and spin correlations. There should be good coverage of np spin correlations by 1986. Additional facilities are outlined for polarized beam nucleon and nuclear physics. 15 references.

van Dyck, O.B.; McNaughton, M.W.

1984-01-01

268

Gluon Virtuality and Heavy Sea Quark Contributions to the Spin-dependent g1 Structure Function  

International Nuclear Information System (INIS)

We analyze the quark mass dependence of photon gluon fusion in polarized deep inelastic scattering for both the intrinsic and extrinsic gluon distributions of the nucleon. We calculate the effective number of flavors for each of the heavy and light quark photon gluon fusion contributions to the first moment of the spin-dependent structure function g1(x).

1999-01-01

269

Correlation effects in single-particle overlap functions and one-nucleon removal reactions  

CERN Document Server

Single-particle overlap functions and spectroscopic factors are calculated on the basis of the one-body density matrices (ODM) obtained for the nucleus $^{16}O$ employing different approaches to account for the effects of correlations. The calculations use the relationship between the overlap functions related to bound states of the (A-1)-particle system and the ODM for the ground state of the A-particle system. The resulting bound-state overlap functions are compared and tested in the description of the experimental data from (p,d) reactions for which the shape of the overlap function is important.

Gaidarov, M K; Dimitrova, S S; Stoitsov, M V; Antonov, A N; Van Neck, D; Müther, H

1999-01-01

270

Deuteron Spin Structure function g1 at low Q^2  

Science.gov (United States)

The spin structure function g1(x,Q^2) and its moments provide crucial information on the internal structure of the nucleon. At low momentum transfer Q^2, one can study the transition from partonic (quark-gluon) to hadronic (nucleonic) degrees of freedom and test effective theories based on QCD, for instance Chiral Perturbation Theory (ChPT). As Q^2 goes to zero, the first moment of g1 is constrained by the GDH sum rule and its ChPT extensions, which makes measurements of g1 in this region uniquely interesting. As part of the large program of spin structure function measurements with CLAS at Jefferson Lab, the EG4 experiment measured the cross section difference between electron beam and proton/deuteron target spins parallel and antiparallel to each other (and the beam direction) down to small scattering angles (approx. 7 degrees). From these differences, g1 can be extracted, with minimal model uncertainties, down to Q^2 as low as 0.01 GeV^2. We will give a brief overview of the experiment and its analysis, and present first preliminary results on the deuteron spin structure function g1d(x,Q^2).

Adhikari, Krishna; Kuhn, Sebastian

2012-10-01

271

EMS effect and QCD evolution of three-quark picture of a nucleon  

International Nuclear Information System (INIS)

[en] EMC effect is investigated using QCD approach based on effect of nucleon swelling in nucleus and three-quark structure of nucleon. A model, taking account of exchange of color objects (valent quarks, gluons, quark-antiquark sea interactions) and resulting in increase of nuclear nucleon size in the range of Bjorken variable values 0.25?x?0.65, is briefly described. Comparison of experimental data for dependences of deuterium and iron structure functions (SF) (as well as their R ratios) on transferred momentum square and fixed values of x variable is carried out. The calculated values for SF (D) and SF (Fe) and available experimental data are compared. It is noted that the suggested approach permitted to trace the effects of nucleon swelling in nuclei and to show different character of valon distribution in nucleons and nuclei

1987-01-01

272

Nucleon electromagnetic form factors in a hypercentral quark model  

International Nuclear Information System (INIS)

We study the nucleon electromagnetic form factors within the frame work of hypercentral quark model. We have calculated nucleon electromagnetic form factors at low Q2. We calculate the nucleon form factors using hypercentral wave function. The general nature of the nucleon form factors at low Q2 is consistent with the experimental results.

2013-06-03

273

High energy nucleon incident optical potential by relativistic impulse approximation  

International Nuclear Information System (INIS)

[en] 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)

2000-01-01

274

The second moments of quark and gluon distribution functions in nucleon  

International Nuclear Information System (INIS)

The second moments of quark and gluon distribution functions in proton are calculated on the basis of the QCD sum rule approach. The results obtained are in a good agreement with the experimental data.

1985-01-01

275

Sum rule measurements of the spin-dependent compton amplitude (nucleon spin structure at Q2 = 0)  

International Nuclear Information System (INIS)

[en] Energy weighted integrals of the difference in helicity-dependent photo-production cross sections (?1/2 - ?3/2) provide information on the nucleon's Spin-dependent Polarizability (?), and on the spin-dependent part of the asymptotic forward Compton amplitude through the Drell-Hearn-Gerasimov (DHG) sum rule. (The latter forms the Q2=0 limit of recent spin-asymmetry experiments in deep-inelastic lepton-scattering.) There are no direct measurements of ?1/2 or ?3/2, for either the proton or the neutron. Estimates from current ?-photo-production multipole analyses, particularly for the proton-neutron difference, are in good agreement with relativistic-l-loop Chiral calculations (?PT) for ? but predict large deviations from the DHG sum rule. Either (a) both the 2-loop corrections to the Spin-Polarizability are large and the existing multipoles are wrong, or (b) modifications to the Drell-Hearn-Gerasimov sum rule are required to fully describe the isospin structure of the nucleon. The helicity-dependent photo-reaction amplitudes, for both the proton and the neutron, will be measured at LEGS from pion-threshold to 470 MeV. In these double-polarization experiments, circularly polarized photons from LEGS will be used with SPHICE, a new frozen-spin target consisting of rvec H · rvec D in the solid phase. Reaction channels will be identified in SASY, a large detector array covering about 80% of 4?. A high degree of symmetry in both target and detector will be used to minimize systematic uncertainties

1995-01-01

276

Measurement of the spin-dependent structure function g1(x) of the deuteron  

International Nuclear Information System (INIS)

A measurement of the spin-dependent structure function g1d of the deuteron in the deep inelastic scattering of polarized muons off polarized deuterons, in the kinematical range 0.006222, is presented. The first moment corresponds to a small contribution of the quark spins to the nucleon spin. Using earlier measurements of g1p, the first moment of the spin-dependent neutron structure function g1n is inferred. 2 figs., 19 refs.

1993-01-01

277

Structure functions at low Q^2: higher twists and target mass effects  

Energy Technology Data Exchange (ETDEWEB)

We review the physics of structure functions at low Q{sup 2}, focusing on the phenomenon of quark-hadron duality and the resonance-scaling transition, both phenomenologically and in the context of quark models. We also present a new implementation of target mass corrections to nucleon structure functions which, unlike existing treatments, has the correct kinematic threshold behavior at finite Q{sup 2} in the x -> 1 limit.

Wally Melnitchouk

2006-05-22

278

Spin structure functions at low Q**2 from JLab data  

Energy Technology Data Exchange (ETDEWEB)

Spin structure functions of the nucleon in the regionof large x and small to moderate Q^2 continue to be of high current interest. Among the topics one can study in this kinematic regime are the Q^2 evolution of the first moment of g1 and the behavior of the virtual photon asymmetry A1 at large x. A large experimental program to measure these observables for the proton and deuteron has been concluded at Jefferson Lab Hall B. We will present the results of the 1.6 and 5.7 GeV data.

K.V. Dharmawardane

2007-01-01

279

Dynamical rescaling and universality of hadron structure functions  

International Nuclear Information System (INIS)

[en] The authors argue that pion and nucleon structure functions differ principally due to their different numbers of quarks and different scales of confinement. The former generates an x rescaling while the latter, in QCD, gives rise to a Q2 rescaling. Together these lead to the relation Fsub(?)(x, Q2) = Fsub(N)(2/3) x, zetasub(N?) (Q2) with zetasub(N?) approx.= 0.16, for x values away from the end points. This relation is in good agreement with data. (author)

1984-01-01

280

Deuteron A(Q2) structure function and the neutron electric form factor  

International Nuclear Information System (INIS)

We present new measurements of the deuteron A(Q2) structure function in the momentum transfer region between 1 and 18 fm-2. The accuracy of the data ranges from 2% to 6%. We investigate the sensitivity of A(Q2) to the nucleon-nucleon interaction and to the neutron electric form factor GEn. Our analysis shows that below 20 fm-2 GEn can be inferred from these data with a significantly improved accuracy. The model dependence of this analysis is discussed.

1989-01-01

 
 
 
 
281

Structure and Function of Otoliths.  

Science.gov (United States)

Current data on the structure and function of the otoliths are reviewed. The function of the otolith organ in microgravity is discussed. Biophysical approaches to its study are presented. Theoretical and practical theories, which may be important, because...

A. A. Shipov A. V. Kondrachuk

1986-01-01

282

Covariant calculation of the nucleon and nucleon ? ? form factor  

International Nuclear Information System (INIS)

All four nucleon electromagnetic form factors can be very well described by a manifestly covariant nucleon wave function with zero orbital angular momentum. The same model gives a qualitative description of deep inelastic scattering. The results for the G*M form factor of the N ? ? transition are consistent with other quark models. Presented at the 20th Few-Body Conference, Pisa, Italy, 10-14 September 2007. (author)

2008-01-01

283

Nucleon-alpha potentials  

International Nuclear Information System (INIS)

The nucleon-alpha potential is calculated using a microscopic model with antisymmetrisation effects included from Brink and Boeker, Soper and Serber nucleon-nucleon interactions. The energy dependence of the potentials is also derived. (Auth.)

1977-09-12

284

The Structure of the Nucleon and it's Excited States  

Energy Technology Data Exchange (ETDEWEB)

The past year has been an exciting and productive one for particle physics research at Abilene Christian University. The thrust of our experimental investigations is the study of the nucleon and its excited states. Laboratories where these investigations are presently being conducted are the AGS at Brookhaven, Fermilab and LAMPF. Some analysis of the data for experiments at the Petersburg Nuclear Physics Institute (Gatchina, Russia) is still in progress. Scheduling of activities at different laboratories inevitably leads to occasional conflicts. This likelihood is increased by the present budget uncertainties at the laboratories that make long-term scheduling difficult. For the most part, the investigators have been able to avoid such conflicts. Only one experiment received beam time in 1994 (E890 at the AGS). The situation for 1995-1996 also appears manageable at this point. E890 and another AGS experiment (E909) will run through May, 1995. El 178 at LAMPF is presently scheduled for August/September 1995. E866 at Fermilab is scheduled to start in Spring/Summer 1996. Undergraduate student involvement has been a key element in this research contract since its inception. Summer students participated at all of the above laboratories in 1994 and the same is planned in 1995. A transition to greater involvement by graduate students will provide cohesiveness to ACU involvement at a given laboratory and full-time on-site involvement in the longer running experiments at FNAL and BNL. Funds to support a full-time graduate student are requested this year. Finally, collaboration by Russian, Croatian and Bosnian scientists has proven to be mutually beneficial to these experimental programs and to the overall programs at the institutions involved. Past support has been augmented by other grants from government agencies and from the Research Council at Abilene Christian University. Additional funds are requested in this renewal to enable more programmatic support for these efforts, so that long-range plans can be made to carry out the experiments and to perform the analysis.

None

1995-02-20

285

Density-dependent nucleon-nucleon interaction from UIX three-nucleon force  

CERN Multimedia

A density-dependent two-nucleon potential has been derived in the formalism of correlated basis function. The effects of 3-particle interactions has been included by integrating out the degrees of freedom of the third nucleon. The potential can be easily employed in nuclear matter calculations. It yields results in agreement with those obtained from the underlying three-body potential. The use of the density dependent potential allowed us to study the effects of three-nucleon interactions in symmetric nuclear matter within the Auxiliary Field Diffusion Monte Carlo (AFDMC) computational scheme.

Lovato, Alessandro; Fantoni, Stefano; Illarionov, Alexey Yu; Schmidt, Kevin E; 10.1088/1742-6596/336/1/012016

2012-01-01

286

Three-Nucleon Forces Revisited - Some Historical Thoughts  

CERN Multimedia

Historic steps in the emergence, the derivation and the use of three-nucleon forces, genuine and effective, for calculations of few-nucleon systems and of the structure of heavier nuclei are recalled. The research focus is on few-nucleon systems. The need of three-nucleon forces for a successful description of some data and the remaining puzzles of other data, not explainable despite the inclusion of three-nucleon forces, are discussed.

Sauer, Peter U

2013-01-01

287

A-dependence of weak nuclear structure functions  

CERN Document Server

Effect of nuclear medium on the weak structure functions $F_2^A(x,Q^2)$ and $F_3^A(x,Q^2)$ have been studied using charged current (anti)neutrino deep inelastic scattering on various nuclear targets. Relativistic nuclear spectral function which incorporate Fermi motion, binding and nucleon correlations are used for the calculations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, $F_i^A/F_i^{proton}$ and $F_i^A/F_i^{deuteron}$(i=2,3, A=$^{12}C$, $^{16}O$, $CH$ and $H_{2}O$) are obtained.

Haider, H; Athar, M Sajjad

2013-01-01

288

The structure of functions  

CERN Document Server

This book deals with the constructive Weierstrassian approach to the theory of function spaces and various applications. The first chapter is devoted to a detailed study of quarkonial (subatomic) decompositions of functions and distributions on euclidean spaces, domains, manifolds and fractals. This approach combines the advantages of atomic and wavelet representations. It paves the way to sharp inequalities and embeddings in function spaces, spectral theory of fractal elliptic operators, and a regularity theory of some semi-linear equations. The book is self-contained, although some parts may

Triebel, Hans

2012-01-01

289

Comparing Some Nucleon-Nucleon Potentials  

CERN Multimedia

The aim is to compare a few Nucleon-Nucleon (NN) potentials especially Reid68, Reid68-Day, Reid93, UrbanaV14, ArgonneV18, Nijmegen 93, Nijmegen I, Nijmegen II. Although these potentials have some likenesses and are almost phenomenological, they include in general different structures and its own characteristics. The potentials are constructed in a manner that fit the NN scattering data or phase shifts and are compared in this way. A high-quality scale of a potential is that it fits the data with $\\chi^{2}/N_{data} \\approx 1$, describes well deuteron properties or gives satisfactory results in nuclear structure calculations. However, these scales have some failures. Here, we first compare many potentials by confronting with data. Then, we try to compare the potential forms by considering the potential structures directly and therefore regarding their substantial basis somehow. On the other hand, since the potentials are written in different schema, it is necessary to write the potentials in a unique schema to ...

Naghdi, M

2013-01-01

290

Experiments on polarised lepton scattering off polarised nucleons  

International Nuclear Information System (INIS)

[en] The current experimental status of the spin dependent structure functions as measured in polarised deep inelastic scattering of charged leptons from nucleons is reviewed. The proposals for new experiments at SLAC and HERA are discussed. Special emphasis is put on the experiment of the Spin Muon Collaboration at CERN which has started taking data in 1991. (orig.)

1992-01-01

291

Measurement of the spin structure function G^P_1 (X, Q^2) with CLAS at Jefferson Lab  

Energy Technology Data Exchange (ETDEWEB)

Inelastic scattering using polarized nucleon targets and polarized charged lepton beams allows the extraction of the structure functions g1 and g2 which provide information on the spin structure of the nucleon. A program designed to study such processes has been underway in Jefferson Lab since 1998. A polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the desired data. The measurements cover the resonance region with unprecedented detail and add significantly to the DIS data set at low to moderate Q^2 and moderate to high x. The measured electron asymmetries are analyzed to produce quantities of interest, such as the photon-nucleon asymmetry AP1+, the spin structure function gP1 and its first moment Gamma1.

Yelena Prok

2005-02-01

292

Deformed chiral nucleons  

Energy Technology Data Exchange (ETDEWEB)

We compute properties of the nucleon in a hybrid chiral model based on the linear {sigma}-model with quark degrees of freedom treated explicity. In contrast to previous calculations, we do not use the hedgehog ansatz. Instead we solve self-consistently for a state with well defined spin and isospin projections. We allow this state to be deformed and find that, although d- and g-state admixtures in the predominantly s-state single quark wave functions are not large, they have profound effects on many nucleon properties including magnetic moments and g{sub A}. Our best fit parameters provide excellent agreement with experiment but are much different from those determined in hedgehog calculations. (orig.).

Price, C.E.; Shepard, J.R. (Colorado Univ., Boulder (USA). Dept. of Physics)

1991-04-18

293

Deformed chiral nucleons  

International Nuclear Information System (INIS)

[en] We compute properties of the nucleon in a hybrid chiral model based on the linear ?-model with quark degrees of freedom treated explicity. In contrast to previous calculations, we do not use the hedgehog ansatz. Instead we solve self-consistently for a state with well defined spin and isospin projections. We allow this state to be deformed and find that, although d- and g-state admixtures in the predominantly s-state single quark wave functions are not large, they have profound effects on many nucleon properties including magnetic moments and gA. Our best fit parameters provide excellent agreement with experiment but are much different from those determined in hedgehog calculations. (orig.)

1991-04-18

294

Nucleon Spin Physics with CLAS at Jlab  

Energy Technology Data Exchange (ETDEWEB)

The spin structure of the nucleon has been investigated for now more than three decades using lepton and photon beams. Measurements of the spin-dependent structure functions g{sub 1} and g{sub 2} have been performed at large Q{sup 2} (Deep Inelastic Scattering or DIS region) at SLAC, CERN, and DESY [1], providing information for the understanding of nucleon structure in terms of elementary constituents of QCD, quarks and gluons. On the contrary much less was known in the low momentum transfer region (Q{sup 2} < 1-2 GeV{sup 2}), where perturbative QCD cannot be applied and non-perturbative phenomena as nucleon resonances play a dominant role. Lattice gauge theories will hopefully provide the connections between composite hadrons and fundamental constituents in this regime. However presently phenomenological models are still the main tool for the description of the hadron properties. The very low momentum transfer region (Q{sup 2} < 0.05 - 0.1 GeV{sup 2}) is described by Chiral Perturbation Theory ({chi}PT), an effective representation of QCD in the low energy limit. Testing {chi}PT is clearly very important to identify the relevant degrees of freedom in this kinematic domain. A broad program to measure the inclusive spin structure of the nucleon via polarized electron scattering o. a polarized target was conducted between 1998 and 2006 with the CLAS detector [2] in Hall B at Jefferson Lab and the most recent data are the subject of this report.

M. Ripani

2007-02-01

295

Alveolar structure and function  

CERN Document Server

In the distal regions of the human lung, one of the most challenging problems facing a large multicellular organism is solved-ensuring an adequate supply of oxygen for aerobic tissue metabolism while removing associated waste products. Conduits for both air and blood converge at the alveolar level to match ventilation with perfusion and thus assure the free diffusion of oxygen and carbon dioxide. Despite their thin walls and their intimate relationship to the pulmonary capillary bed, the alveolus must present a barrier function robust enough to resist alveolar flooding from the hydrostatic pre

Payne, D Keith

2012-01-01

296

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 ?N and ?? physical regions of the N anti N ? ?? 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

1981-01-01

297

Roles of quarks and gluons in the spin structure of nucleons  

Energy Technology Data Exchange (ETDEWEB)

The spin structure of protons will be discussed by using MIT-bag model and considering constituent quarks to be combined from current quarks and gluons. It will be shown that the gluonic degrees of freedom play an important role in prediction of the recent EMC results. (orig.).

Modarres, M. (AEOI, Teheran (Iran, Islamic Republic of). Center for Theoretical Physics and Mathematics Amir-Kabir Univ., Teheran (Iran, Islamic Republic of). Physics Dept.); Ghafoori-Tabrizi, K. (AEOI, Teheran (Iran, Islamic Republic of). Center for Theoretical Physics and Mathematics Shahid-Beheshti Univ., Teheran (Iran, Islamic Republic of). Physics Dept.)

1992-11-01

298

Do Gluons Carry Half of the Nucleon Momentum?  

International Nuclear Information System (INIS)

[en] We examine the conventional picture that gluons carry about half of the nucleon momentum in the asymptotic limit. We show that this large fraction is due to an unsuitable definition of the gluon momentum in an interacting theory. If defined in a gauge-invariant and consistent way, the asymptotic gluon momentum fraction is computed to be only about one-fifth. This result suggests that the asymptotic limit of the nucleon spin structure should also be reexamined. A possible experimental test of our finding is discussed in terms of novel parton distribution functions.

2009-08-07

299

Do gluons carry half of the nucleon momentum?  

CERN Document Server

We examine the conventional picture that gluons carry about half of the nucleon momentum in the asymptotic limit. We reveal that this large fraction is due to an unsuitable definition of the gluon momentum in an interacting theory. If defined in a gauge-invariant and consistent way, the asymptotic gluon momentum fraction is computed to be only about one fifth. This result suggests that the asymptotic limit of the nucleon spin structure should also be reexamined. Possible experimental test of our finding is discussed in terms of novel parton distribution functions.

Chen Xiang Song; Lü, Xiao-Fu; Wang, Fan; Goldman, T

2009-01-01

300

First measurement of the gluon polarisation in the nucleon using D mesons at COMPASS  

CERN Document Server

The complicated structure of the nucleon has been studied with great success in deep-inelastic lepton-nucleon scattering (DIS) experiments at CERN, SLAC and DESY. As a result the unpolarised structure functions have been measured accurately over a wide kinematic range. From these measurements it is possible to determine the gluon density in the nucleon with good accuracy via a so-called QCD fit. In the case of the spin structure of the nucleon the situation is different. Even after decades of experimental and theoretical efforts it remains to be understood how the spin of the nucleon of 1/2 in units of h-bar is to be accounted for in terms of contributions from the quarks and gluons inside the nucleon. Of particular interest is the question whether the polarised gluon density can explain the unexpected smallness of the quark contribution to the nucleon spin. The QCD fit, which worked well in the unpolarised case, yields a polarised gluon density Delta G which is only badly constrained. This is due to the fact...

von Hodenberg, Martin

2005-01-01

 
 
 
 
301

The Spin Asymmetries of the Nucleon Experiment  

Science.gov (United States)

The Spin Asymmetries of the Nucleon Experiment (SANE) measured the virtual Compton scattering asymmetries, A1 and A2, from which the spin structure functions of the proton, g1 and g2, can be obtained. The kinematics for these measurements are in a range of Bjorken x, 0.3 Lucite hodoscope and a large array of lead glass detectors. In addition to motivating the physics of the proton's spin structure we shall discuss the analysis and present preliminary results.[0pt] [1] M. Burkardt, AIP Conf. Proc. 1149, 62 (2009) [arXiv:0902.0163 [hep-ph

Armstrong, Whitney

2011-10-01

302

Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC  

CERN Document Server

We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process. Additional tests of...

Frankfurt, L; Weiss, C

2010-01-01

303

What can be learned about meson nucleon interactions and nuclear structure from K{sup +} total cross sections  

Energy Technology Data Exchange (ETDEWEB)

K{sup +} total cross sections on deuterium, {sup 6}Li, {sup 12}C, {sup 28}Si and {sup 40}Ca have been measured at four momenta in the range of 480--714 MeV/c. This study has revealed important modifications of the free-space K{sup +}-nucleon interaction when the nucleon is embedded in a nucleus. Some of the suggested modifications include unconventional nuclear medium effects such as partial quark deconfinement, mass rescaling of nuclear pionic fields or pion excess in nuclei and meson exchange currents.

Sawafta, R.

1993-11-01

304

On Nuclear Structure Effects in the Nucleon-Induced Fission Cross Sections of Nuclei near 208Pb at Intermediate Energies  

International Nuclear Information System (INIS)

Recently measured energy dependences of fission cross sections of lead isotopes 204,206-208Pb at incident nucleon energies up to 180 MeV were analyzed. Regularities were established of the fission cross-section variation with the mass number of isotopes pointing to incomplete dumping of shell effects even at nucleon energies 150-180 MeV. The fission cross sections of lead isotopes, assumed as spherical nuclei, are compared with those of deformed nuclei. The experimental data are compared with calculations by the code TALYS

2005-05-24

305

Spin observables in nucleon-nucleus scattering  

Energy Technology Data Exchange (ETDEWEB)

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.

Moss, J.M.

1982-01-01

306

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

1982-03-27

307

Effects of multiquark bags in the quark potential model. Applications to nucleon-nucleon scattering  

International Nuclear Information System (INIS)

[en] The effects of the explicit treatment of multiquark confined states in the quark potential model are studied for the two-nucleon system. The confined six-quark component in the nucleon-nucleon wave function is shown to generate a new mechanism for the short-range nucleon-nucleon interaction which qualitatively reproduces both the repulsion and medium-range attraction properties of the nuclear force. It is found that for an appropriate choice of parameters the NN forces generated by an admixture of multiquark confined states can bind the six-quark system in the deuteron-like bound state and qualitatively reproduces the low-energy phase-shift behaviour. Obtained results may be also considered as the first example of dynamical calculations of nucleon-nucleon scattering in the quark compound bag method using the explicit form of the six quark Hamiltonian

1987-01-01

308

Operators of deep inelastic scattering in meson-nucleon theory  

International Nuclear Information System (INIS)

Scalar mesons are used as an example to present the nonrelativistic meson-nucleon theory for deep inelastic scattering of leptons by the neutron. The Wilson operator expansion is used to obtain explicitly the nonrelativistic operators for deep inelastic scattering in terms of interacting nucleon and meson fields. An analytic expression is obtained for the second moments of the structure functions (with accuracy up to g2), and the contributions of the self-energy parts and meson exchange currents are extracted. It is shown that the deuteron moments can be expressed in terms of the physically observable moments of the constituents -- nucleons and mesons. It is shown that the energy-momentum conservation law, violated in the impulse approximation, is exactly restored by taking into account the contribution of the meson exchange currents. 28 refs., 2 figs.

1992-01-01

309

Peripheral ER Structure to Function  

Science.gov (United States)

Summary The endoplasmic reticulum (ER) is a single continuous membrane-enclosed organelle made up of functionally and structurally distinct domains. The ER domains include the nuclear envelope (NE) and the peripheral ER, which is a network of tubules and sheets spread throughout the cytoplasm. The structural organization of the ER is related to its many different cellular functions. Here we will discuss how the various functional domains of the peripheral ER are organized into structurally distinct domains that exist within the continuous membrane bilayer throughout the cell cycle. In addition, we will summarize our current knowledge on how peripheral ER membranes contact various other regions of the cytoplasm including the cytoskeleton, mitochondria, Golgi, and the plasma membrane and what is known about the functions of these interactions.

English, Amber R.; Zurek, Nesia; Voeltz, Gia K.

2009-01-01

310

Non-singlet spin structure function in valon model  

Energy Technology Data Exchange (ETDEWEB)

We present a Next-to-leading order QCD calculation of non-singlet spin structure function g{sub 1}{sup NS}(x,Q{sup 2}), of the nucleon in the so-called the valon representation. The structure of the valon itself develops through the perturbative dressing of a valence quark in QCD, which is independent of the hosting hadron. The results of this calculations are in excellent agreement with the experimental data from HERMES collaborations for the entire measured range of x. It also provides an acceptable agreement with the older data from SMC, E143 and E155 experiments. We have further compared our results with those from AA, BB, GRSV, and DNS global fits.

Taghavi Shahri, Fatemeh [School of Particles and Accelerators,IPM, Institute for Studies in Theoretical Physics and Mathematics, P.O.Box 19395-5531, Tehran (Iran); Arash, Firooz [Department of Physics, Tafresh University, Tafresh (Iran)

2009-07-01

311

Non-singlet spin structure function in valon model  

International Nuclear Information System (INIS)

We present a Next-to-leading order QCD calculation of non-singlet spin structure function g1NS(x,Q2), of the nucleon in the so-called the valon representation. The structure of the valon itself develops through the perturbative dressing of a valence quark in QCD, which is independent of the hosting hadron. The results of this calculations are in excellent agreement with the experimental data from HERMES collaborations for the entire measured range of x. It also provides an acceptable agreement with the older data from SMC, E143 and E155 experiments. We have further compared our results with those from AA, BB, GRSV, and DNS global fits.

2009-01-01

312

Pion-nucleon partial wave analysis and study of baryon structure. Progress report, June 1, 1979-May 31, 1981  

International Nuclear Information System (INIS)

This report details progress toward completion of a long-term pion-nucleon partial wave analysis, summarizing results and conclusions to date. The report also discussed progress in using partial wave and resonance parameter results to test dynamical models of the baryon and in better understanding interquark forces within baryons

1981-01-01

313

Structure function measurements at HERA  

International Nuclear Information System (INIS)

We report on the deep inelastic scattering structure functions measured by the ZEUS and H1 experiments at HERA from collisions of 27.5 GeV positrons and 820 GeV protons. The F2 structure function of the proton has been measured down to Q2=0.11 GeV2 and shows good agreement with perturbative QCD down to Q2=1.5 GeV2. The preliminary F2cc-bar cross section from 1995 measured in the range 3?Q2?170 GeV2 is consistent with the gluon extracted from F2 scaling violations. F2cc-bar is about 25% of the F2 structure function over this Q2 range.

1998-05-29

314

Structure function measurements at HERA  

Science.gov (United States)

We report on the deep inelastic scattering structure functions measured by the ZEUS and H1 experiments at HERA from collisions of 27.5 GeV positrons and 820 GeV protons. The F2 structure function of the proton has been measured down to Q2=0.11 GeV2 and shows good agreement with perturbative QCD down to Q2=1.5 GeV2. The preliminary F2cc cross section from 1995 measured in the range 3<=Q2<=170 GeV2 is consistent with the gluon extracted from F2 scaling violations. F2cc is about 25% of the F2 structure function over this Q2 range.

Wodarczyk, Michael J.

1998-05-01

315

Direct instantons in QCD nucleon sum rules  

CERN Document Server

We study the role of direct (i.e. small-scale) instantons in QCD correlation functions for the nucleon. They generate sizeable, nonperturbative corrections to the conventional operator product expansion, which improve the quality of both QCD nucleon sum rules and cure the long-standing stability problem, in particular, of the chirally odd sum-rule.

Forkel, H; Forkel, Hilmar; Banerjee, Manoj K.

1993-01-01

316

Nucleon currents between highly excited nuclei  

Energy Technology Data Exchange (ETDEWEB)

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.

Barranco, M.P.M.; Vinas, X. (Barcelona Univ. (Spain). Facultad de Fisica); Ngo, C.; Tomasi, E. (CEA Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Physique Nucleaire)

1983-09-19

317

Structure Functions of Bound Neutrons  

Energy Technology Data Exchange (ETDEWEB)

We describe an experiment measuring electron scattering on a neutron bound in deuterium with coincident detection of a fast, backward-going spectator proton. Our data map out the relative importance of the pure PWIA spectator mechanism and final state interactions in various kinematic regions, and give a first glimpse of the modification of the structure function of a bound neutron as a function of its off-shell mass. We also discuss a new experimental program to study the structure of a free neutron by extending the same technique to much lower spectator momenta.

Sebastian Kuhn

2005-04-01

318

Structure Functions of Bound Neutrons  

International Nuclear Information System (INIS)

We describe an experiment measuring electron scattering on a neutron bound in deuterium with coincident detection of a fast, backward-going spectator proton. Our data map out the relative importance of the pure PWIA spectator mechanism and final state interactions in various kinematic regions, and give a first glimpse of the modification of the structure function of a bound neutron as a function of its off-shell mass. We also discuss a new experimental program to study the structure of a free neutron by extending the same technique to much lower spectator momenta

2005-10-06

319

QCD at low Q2 - a correspondence relation for moments of structure functions  

International Nuclear Information System (INIS)

The precocious validity of QCD predictions in deep inelastic lepton nucleon scattering and e+e- annihilation is interpreted as a signal for an underlying 'correspondence principle' relating perturbative and nonperturbative physics on the Q2 average. Correspondence relations for nonsinglet moments of deep inelastic structure functions are formulated, discussed and successfully tested against experiment. The relations provide an independent determination of the QCD ?-parameter from low Q2 data in perfect agreement with results from large Q2 analyses. (author)

1980-01-01

320

Local duality in spin structure functions g1(p) and g1(d)  

International Nuclear Information System (INIS)

Inclusive double spin asymmetries obtained by scattering polarized electrons off polarized protons and deuterons have been analyzed to address the issue of quark hadron duality in the polarized spin structure functions gp 1 and gd 1. A polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the data. The resulting gp 1 and gd 1 were averaged over the nucleon resonance energy region (M

2006-01-01

 
 
 
 
321

Perturbative QCD study of the polarized structure function g1 at Next-to-Leading-Order  

International Nuclear Information System (INIS)

A NLO perturbative study of all available data on polarized structure function g1(x,Q2) is presented. It is first explained how the Q2 evolution was performed using the DGLAP equations, which used with the present data, allow to constrain the behaviour of polarized parton distributions. Implications of such a study are discussed and important quantities are derived such as an estimation of the quark and gluon polarizations in the nucleon. (author)

1998-01-01

322

Dynamical rescaling, the EMC effect and universality of hadron structure functions  

International Nuclear Information System (INIS)

[en] Data are compared on the EMC effect, with the hypothesis that the quark confinement size increases in going from a free nucleon to a nucleus. In QCD a dynamical rescaling is predicted: Q2 variation of the distribution function in a given target parallels the dependence on confinement size, R, at fixed Q2. Thus a dynamical scale invariance obtains when both R and Q2 are varied, yielding the dynamical rescaling relation F2sup(A)(x, Q2) = F2sup(N)(x, zetaQ2) where zeta > 1 is predicted for any nucleus and is a function of the confinement size. Data on 12 nuclei agree with this, implying that confinement size is governed by nuclear density. The formalism is tested by relating the pion and nucleon structure functions. (author)

1984-01-01

323

Dynamical rescaling, the EMC effect and universality of hadron structure functions  

International Nuclear Information System (INIS)

[en] Data are compared on the EMC effect with the hypothesis that the quark confinement size increases in going from a free nucleon to a nucleus. In QCD a dynamical rescaling is predicted: Q2 variation of the distribution function in a given target parallels the dependence on confinement size, R, at fixed Q2. Thus a dynamical scale invariance obtains when both R and Q2 are varied, yielding the dynamical rescaling relation: Fsub(2)sup(A)(x,Q2) = Fsub(2)sup(N)(x,zetaQ2) where zeta > 1 is predicted for any nucleus and is a function of the confinement size. Data on 12 nuclei agree with this, implying that confinement size is governed by nuclear density. The formalism is tested by relating the pion and nucleon structure functions

1984-01-01

324

Bound-state quark and gluon contributions to structure functions in QCD  

International Nuclear Information System (INIS)

One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: ''intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and ''extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic ''bound-valence'' and extrinsic ''non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs

1990-01-01

325

The correlation functions and emission time scales for light particles and light fragments in 40Ar+197Au reactions at 25 MeV/nucleon  

International Nuclear Information System (INIS)

Two-particle correlation functions were measured for the emission of protons, deuterons, tritons, ?, and lithium fragment at small relative momenta in 40Ar-induced reactions on 197Au at 25 MeV/nucleon. Based on three-body trajectory calculations the emission time scales for the particles were extracted from p-d, d-d, t-t, and lithium-lithium correlation functions.The mean emission time was found to decrease with increasing sum of the kinetic energies of the particle in a correlated pairs, indicating the emission of more energetic particles at earlier stages of the reaction than at later stages. The time scale for the emission of lithium fragments emission suggests that sequential binary disassembly occurs in 40Ar+197Au reaction at MeV/nucleon. The mean emission temperatures of 3.5+1.3-0.8 and 3.6±0.4 MeV were also extracted from the relative populations of the excited and ground states of the respective emitted nuclides 8Be and 4He. (orig.).

1997-01-01

326

The correlation functions and emission time scales for light particles and light fragments in {sup 40}Ar+{sup 197}Au reactions at 25 MeV/nucleon  

Energy Technology Data Exchange (ETDEWEB)

Two-particle correlation functions were measured for the emission of protons, deuterons, tritons, {alpha}, and lithium fragment at small relative momenta in {sup 40}Ar-induced reactions on {sup 197}Au at 25 MeV/nucleon. Based on three-body trajectory calculations the emission time scales for the particles were extracted from p-d, d-d, t-t, and lithium-lithium correlation functions.The mean emission time was found to decrease with increasing sum of the kinetic energies of the particle in a correlated pairs, indicating the emission of more energetic particles at earlier stages of the reaction than at later stages. The time scale for the emission of lithium fragments emission suggests that sequential binary disassembly occurs in {sup 40}Ar+{sup 197}Au reaction at MeV/nucleon. The mean emission temperatures of 3.5{sup +1.3}{sub -0.8} and 3.6{+-}0.4 MeV were also extracted from the relative populations of the excited and ground states of the respective emitted nuclides {sup 8}Be and {sup 4}He. (orig.).

He Zhiyong [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Duan Limin [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Jin Genming [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Li Zuyu [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Wu Heyu [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Zhang Baoguo [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Wen Wanxin [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Qi Yujin [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Luo Qingzheng [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.; Dai Guangxi [Chinese Acad. of Sci., Lanzhou (China). Inst. of Modern Phys.

1997-07-07

327

Study of nucleon-nucleon and hyperon-nucleon interaction  

International Nuclear Information System (INIS)

In this paper we review recent investigations of nucleon-nucleon and hyperon-nucleon interactions employing a non-relativistic quark cluster model. We concentrate mainly on the short and medium-range behavior of the baryon-baryon interaction based on the one-gluon and meson exchange potentials. The chiral quark model based on pion and sigma exchange between quarks is also discussed. We also review a study of the deuteron and its electromagnetic properties in a quark model with exchange currents. (author)

2000-01-01

328

Study of nucleon-nucleon and hyperon-nucleon interaction  

Energy Technology Data Exchange (ETDEWEB)

In this paper we review recent investigations of nucleon-nucleon and hyperon-nucleon interactions employing a non-relativistic quark cluster model. We concentrate mainly on the short and medium-range behavior of the baryon-baryon interaction based on the one-gluon and meson exchange potentials. The chiral quark model based on pion and sigma exchange between quarks is also discussed. We also review a study of the deuteron and its electromagnetic properties in a quark model with exchange currents. (author)

Shimizu, Kiyotaka [Department of Physics, Sophia University, Tokyo (Japan); Takeuchi, Sachiko [Japan College of Social Work, Kiyose (Japan); Buchmann, A.J. [Institute for Theoretical Physics, University of Tuebinge (Germany)

2000-04-01

329

Nucleon-nucleon interaction at medium energies  

International Nuclear Information System (INIS)

A summary of the medium energy nucleon-nucleon elastic and inelastic scattering data is presented from an experimenter's viewpoint. Motivation for additional measurements is given. Experiments which rely on the unique capabilities of the Indiana Cooler are emphasized. 65 references

1984-01-01

330

Theory of diffractive structure functions  

Energy Technology Data Exchange (ETDEWEB)

We discuss the connection between the dipole approach and the DIS structure functions. Particular emphasis is given to DIS diffraction. We report on current work on the NLO photon impact factor. As an application of the dipole approach in DIS diffraction, we discuss the diffractive production of jets and of charm. (author)

Bartels, J. [II. Institut fuer Theoretische Physik, Universitaet Hamburg, Hamburg (Germany)]. E-mail: bartels@x4u2.desy.de

2002-05-01

331

Theory of diffractive structure functions  

International Nuclear Information System (INIS)

We discuss the connection between the dipole approach and the DIS structure functions. Particular emphasis is given to DIS diffraction. We report on current work on the NLO photon impact factor. As an application of the dipole approach in DIS diffraction, we discuss the diffractive production of jets and of charm. (author)

2002-01-01

332

Non-empirical energy density functional for the nuclear structure  

International Nuclear Information System (INIS)

The energy density functional (EDF) formalism is the tool of choice for large-scale low-energy nuclear structure calculations both for stable experimentally known nuclei whose properties are accurately reproduced and systems that are only theoretically predicted. We highlight in the present dissertation the capability of EDF methods to tackle exotic phenomena appearing at the very limits of stability, that is the formation of nuclear halos. We devise a new quantitative and model-independent method that characterizes the existence and properties of halos in medium- to heavy-mass nuclei, and quantifies the impact of pairing correlations and the choice of the energy functional on the formation of such systems. These results are found to be limited by the predictive power of currently-used EDFs that rely on fitting to known experimental data. In the second part of this dissertation, we initiate the construction of non-empirical EDFs that make use of the new paradigm for vacuum nucleon-nucleon interactions set by so-called low-momentum interactions generated through the application of renormalization group techniques. These soft-core vacuum potentials are used as a step-stone of a long-term strategy which connects modern many-body techniques and EDF methods. We provide guidelines for designing several non-empirical models that include in-medium many-body effects at various levels of approximation, and can be handled in state-of-the art nuclear structure codes. In the present work, the first step is initiated through the adjustment of an operator representation of low-momentum vacuum interactions using a custom-designed parallel evolutionary algorithm. The first results highlight the possibility to grasp most of the relevant physics for low-energy nuclear structure using this numerically convenient Gaussian vertex. (author)

2008-01-01

333

Quark-hadron duality in lepton scattering off nucleons  

International Nuclear Information System (INIS)

Quark-hadron (QH) duality in lepton scattering off nucleons is studied with the resonance quark model. It is shown that in the case of neutrino scattering off an isoscalar target the duality is simultaneously observed for charged and neutral currents xF1?N, F2?N, and xF3?N weak structure functions.We demonstrate that the QH duality can be a useful property for modeling structure functions in the so-called resonance region. As an example it is shown that combining relativistic quark model predictions with duality arguments allows a construction of the inclusive resonance F2ep structure function.

2010-03-30

334

Rescaling for kaon structure function  

International Nuclear Information System (INIS)

[en] The authors use the valon model to analyze the kinamical rescaling of x in the inelastic structure functions and point out it to be the delta pproximation of the valon distribution functions. They make use of the contribution of valence quarks to the mass of a hadron in a bound state to determine a few parameters for the x-rescaling and thus obtain teh kaon structure functions: F/sub K//sup ?/(x,Q/sup '2/)=F/sub N//sup ?/(0.75x,zeta/sub NK/Q/sup '2/=Q /sup 2/) F/sub K//sup S/(x,Q/sup '2/)=F/sub N//sup ?/(0.6x, zeta/sub NK/Q/sup '2/=Q /sup 2/) with zeta/sub NK/=0.229, which is consistent with the data well

1986-01-01

335

Theory of doorway states for one-nucleon transfer reactions  

CERN Document Server

The doorway states under consideration are eigenstates of the hamiltonian which is the sum of the kinetic energy and the infinite energy limit of the single-particle mass operator. Only Hartree diagrams with the free-space nucleon-nucleon forces contribute to this limit, and therefore the observed doorway state energies carry an important information about both the nuclear structure and the free-space nucleon-nucleon interaction.

Birbrair, B L

2000-01-01

336

Conflicting coupling of the unpaired nucleons and the structure of collective bands in odd-odd nuclei  

CERN Document Server

Conflicting coupling of unpaired nucleons in the odd-odd nuclei is discussed. A very simple explanation is suggested for the damping of the energy spacing of the lowest levels in the rotational bands in the odd-odd nuclei in the case of a "conflicting" coupling of the odd proton and neutron comparative to those of the bands based on the state of the strongly-coupled particle in the neighbouring odd nuclei entering the "conflicting" configuration.

Levon, A I

2011-01-01

337

SLAC measurement of the neutron spin structure function  

Energy Technology Data Exchange (ETDEWEB)

A measurement of the nucleon spin asymmetries from deep inelastic scattering of polarized electrons by polarized [sup 3]He has been performed. The neutron spin structure function g[sub 1][sup n] is extracted and used to test the Bjorken sum rule. The neutron integral assuming a simple Regge theory extrapolation at low x is [integral][sub 0][sup 1]g[sub 1][sup n](x)dx = [minus]0.022 [plus minus] 0.011. Combined with the EMC proton results, the Bjorken sum rule predicts a neutron integral of [integral][sub 0][sup 1]g[sub 1][sup n](x)dx = [minus]0.065 [plus minus] 0.018.

Hughes, E.

1993-04-01

338

Measurements of Parity-Violating Asymmetries in Electron-Deuteron Scattering in the Nucleon Resonance Region  

Science.gov (United States)

We report on parity-violating asymmetries in the nucleon resonance region measured using inclusive inelastic scattering of 5–6 GeV longitudinally polarized electrons off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the ?(1232). They provide a verification of quark-hadron duality—the equivalence of the quark- and hadron-based pictures of the nucleon—at the (10–15)% level in this electroweak observable, which is dominated by contributions from the nucleon electroweak ?Z interference structure functions. In addition, the results provide constraints on nucleon resonance models relevant for calculating background corrections to elastic parity-violating electron scattering measurements.

Wang, D.; Pan, K.; Subedi, R.; Deng, X.; Ahmed, Z.; Allada, K.; Aniol, K. A.; Armstrong, D. S.; Arrington, J.; Bellini, V.; Beminiwattha, R.; Benesch, J.; Benmokhtar, F.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, J.-P.; Chudakov, E.; Cisbani, E.; Dalton, M. M.; de Jager, C. W.; De Leo, R.; Deconinck, W.; Deur, A.; Dutta, C.; El Fassi, L.; Flay, D.; Franklin, G. B.; Friend, M.; Frullani, S.; Garibaldi, F.; Giusa, A.; Glamazdin, A.; Golge, S.; Grimm, K.; Hafidi, K.; Hansen, O.; Higinbotham, D. W.; Holmes, R.; Holmstrom, T.; Holt, R. J.; Huang, J.; Hyde, C. E.; Jen, C. M.; Jones, D.; Kang, H.; King, P.; Kowalski, S.; Kumar, K. S.; Lee, J. H.; LeRose, J. J.; Liyanage, N.; Long, E.; McNulty, D.; Margaziotis, D. J.; Meddi, F.; Meekins, D. G.; Mercado, L.; Meziani, Z.-E.; Michaels, R.; Mihovilovic, M.; Muangma, N.; Myers, K. E.; Nanda, S.; Narayan, A.; Nelyubin, V.; Nuruzzaman; Oh, Y.; Parno, D.; Paschke, K. D.; Phillips, S. K.; Qian, X.; Qiang, Y.; Quinn, B.; Rakhman, A.; Reimer, P. E.; Rider, K.; Riordan, S.; Roche, J.; Rubin, J.; Russo, G.; Saenboonruang, K.; Saha, A.; Sawatzky, B.; Shahinyan, A.; Silwal, R.; Sirca, S.; Souder, P. A.; Suleiman, R.; Sulkosky, V.; Sutera, C. M.; Tobias, W. A.; Urciuoli, G. M.; Waidyawansa, B.; Wojtsekhowski, B.; Ye, L.; Zhao, B.; Zheng, X.

2013-08-01

339

Measurements of parity-violating asymmetries in electron-deuteron scattering in the nucleon resonance region.  

UK PubMed Central (United Kingdom)

We report on parity-violating asymmetries in the nucleon resonance region measured using inclusive inelastic scattering of 5-6 GeV longitudinally polarized electrons off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the ?(1232). They provide a verification of quark-hadron duality-the equivalence of the quark- and hadron-based pictures of the nucleon-at the (10-15)% level in this electroweak observable, which is dominated by contributions from the nucleon electroweak ?Z interference structure functions. In addition, the results provide constraints on nucleon resonance models relevant for calculating background corrections to elastic parity-violating electron scattering measurements.

Wang D; Pan K; Subedi R; Deng X; Ahmed Z; Allada K; Aniol KA; Armstrong DS; Arrington J; Bellini V; Beminiwattha R; Benesch J; Benmokhtar F; Camsonne A; Canan M; Cates GD; Chen JP; Chudakov E; Cisbani E; Dalton MM; de Jager CW; De Leo R; Deconinck W; Deur A; Dutta C; El Fassi L; Flay D; Franklin GB; Friend M; Frullani S; Garibaldi F; Giusa A; Glamazdin A; Golge S; Grimm K; Hafidi K; Hansen O; Higinbotham DW; Holmes R; Holmstrom T; Holt RJ; Huang J; Hyde CE; Jen CM; Jones D; Kang H; King P; Kowalski S; Kumar KS; Lee JH; Lerose JJ; Liyanage N; Long E; McNulty D; Margaziotis DJ; Meddi F; Meekins DG; Mercado L; Meziani ZE; Michaels R; Mihovilovic M; Muangma N; Myers KE; Nanda S; Narayan A; Nelyubin V; Nuruzzaman; Oh Y; Parno D; Paschke KD; Phillips SK; Qian X; Qiang Y; Quinn B; Rakhman A; Reimer PE; Rider K; Riordan S; Roche J; Rubin J; Russo G; Saenboonruang K; Saha A; Sawatzky B; Shahinyan A; Silwal R; Sirca S; Souder PA; Suleiman R; Sulkosky V; Sutera CM; Tobias WA; Urciuoli GM; Waidyawansa B; Wojtsekhowski B; Ye L; Zhao B; Zheng X

2013-08-01

340

Nucleon scattering and reactions  

Energy Technology Data Exchange (ETDEWEB)

Recent advances in the fundamental calculation of the nucleon optical potential from the nucleon-nucleon interaction and the nuclear density distributions are reviewed, with particular attention to the understanding of the anomaly in the real part of the potential around the Fermi energy. Some data that pose a challenge to theories of the nucleon-nucleon interaction are examined, together with detailed systematics of nuclear RMS charge radii. The application of optical model and distorted wave theory to analyse neutron elastic and inelastic scattering is described.

Hodgson, P.E.

1983-01-01

 
 
 
 
341

CREATINE KINASE: STRUCTURE AND FUNCTION  

Directory of Open Access Journals (Sweden)

Full Text Available TEIXEIRA, A. M.; BORGES, G. F. Creatine kinase: structure and function. Brazilian Journal of Biomotricity. v. 6, n. 2, p. 53-65, 2012. Found in all vertebrates, creatine kinase (CK) is a member of the phosphagen kinase family and catalyzes the reversible phosphotransfer between the ATP/ADP and Creatine/Phosphocreatine systems. CK is highly expressed in excitable tissues that require large energy fluxes and plays a significant role in the energy homeostasis of these tissue cells. The creatine kinase reaction was first identified in 1934 by K Lohman in the muscle tissue and it has undergone intensive investigation for over 80 years. The enzyme is of clinical importance and its levels are routinely used as an indicator of acute myocardial infarction. There are four major CK isoforms, which are named according to their tissue distribution or subcellular localization: two tissue (muscle or brain) cytosolic and two mitochondrial, which form dimers and octamers, respectively. In this paper we will include a brief summary of the history of the detection of creatine kinases isoforms, their main structural features, physical and catalitic properties and multiple functions such as an energy buffering function, metabolic regulatory functions and the energy transport function.

Ana Maria Teixeira; Grasiely F. Borges

2012-01-01

342

On the electron structure function  

International Nuclear Information System (INIS)

The collinear QCD structure of the electron is studied within the Standard Model. The electron structure function is defined and calculated in leading logarithmic approximation. It shows important contribution from the interference of the intermediate electroweak bosons. The problem of momentum scales is extensively discussed. The master equations for the QCD parton densities inside the electron are constructed and solved numerically in the asymptotic region. Significant corrections to the naive evolution procedure are found. Phenomenological applications at present and future momentum scales are discussed. (author)

1996-01-01

343

Study of nuclear effects in the deuteron and extraction of neutron to proton structure function ratio  

Science.gov (United States)

We performed a combined analysis of electron, muon, neutrino, and anti-neutrino deep inelastic scattering structure functions of hydrogen and deuterium, within the framework of quark-parton model. The neutron to proton structure function ratio was obtained using three different techniques: 1) electron and muon scattering experiments on deuterium and hydrogen by using traditional Fermi motion corrections, 2) extrapolation of the EMC effect on heavy targets to deuterium and free nucleons, and 3) using Be and C data. At high x there is a disagreement between these data.

Bodek, A.; Dasu, S.; Rock, S. E.

1992-01-01

344

Spin-structure function of the neutron ({sup 3}He): SLAC results  

Energy Technology Data Exchange (ETDEWEB)

A first measurement of the longitudinal asymmetry of deep-inelastic scattering of polarized electrons from a polarized {sup 3}He target at energies ranging from 19 to 26 GeV has been performed at SLAC. The spin-structure function of the neutron g{sub 1}{sup n} has been extracted from the measured asymmetries allowing for a test of the Ellis-Jaffe and Bjorken sum rules. The Quark Parton Model (QPM) interpretation of the nucleon spin-structure function is examined in light of the new results.

Meziani, Z.E.; E-142 Collaboration

1993-11-01

345

Structure and Function of Glucansucrases  

Science.gov (United States)

Glucansucrases are relatively large (~160 kDa) extracellular enzymes produced by lactic acid bacteria. Using sucrose as a substrate they synthesize high molecular mass glucose polymers, called ?-glucans, which allow the bacteria to adhere to surfaces and create a biofilm. The glucan polymers are of importance for the food and dairy industry as thickening and jellying agents. An overview is given of the current insights into the structure and functioning of these and related enzymes.

Dijkstra, B. W.; Vuji?i?-Žagar, A.

2008-03-01

346

Structure function tests of QCD  

International Nuclear Information System (INIS)

[en] The problems involved in comparing QCD predictions with the Q2 evolution of deep inelastic structure functions are discussed. These involve the resummation of higher order terms approximately equal to (?sub(s) ln(1-z))sup(s) and the use of QCD perturbative analysis in the timelike domain. A comparison is made between theory and experiment for various QCD predictions with and without resummation of the dangerously large terms. The implications for the value of lambda are considered. (author)

1982-01-01

347

QCD analysis of deep inelastic lepton-nucleon scattering data  

International Nuclear Information System (INIS)

[en] A combined next-to-leading order QCD analysis of BCDMS ?H2(D2) and CDHS ?(?-bar)H2 scattering data is presented. The nucleon structure functions are given in terms of parton distributions. Unlike most of the papers on this subject, the cross-section scattering data (not the values for the nucleon structure functions extracted from these data by additional extrapolations and assumptions) are fitted. A very good agreement of the data with the predictions of QCD for the parton distributions is observed. The QCD mass scale parameter ? is determined form these data both in a flavour nonsinglet approximation and with a complete flavour singlet and non-singlet treatment. These two fits to the data give consistent results for ?. (author). 16 refs, 2 tabs

1991-01-01

348

Perturbative QCD predictions for the small x behaviour of unpolarized and polarized deep inelastic scattering structure functions  

International Nuclear Information System (INIS)

The perturbative QCD predictions for the small x behaviour of the nucleon structure functions F2L(x,Q2) and g1(x,Q2) are summarized. The importance of the double logarithmic terms for the small x behaviour of the spin structure function g1(x,Q2) is emphasized. These terms correspond to the contributions containing the leading powers of ?s ln2(1/x) at each order of the perturbative expansion. In the non-singlet case they can be approximately accounted for by the ladder diagrams with quark (antiquark) exchange. We solve the corresponding integral equation with the running coupling effects taken into account and present estimate of the effective slope controlling the small x behaviour of the non-singlet spin structure function g1(x,Q2) of a nucleon. (author)

1996-01-01

349

Spin Structure Function Measurements from E143 at SLAC  

CERN Document Server

Recent high statistics measurements of the nucleon spin structure functions by the E143 Collaboration are presented. The structure functions g sub 1 sup n and g sub 1 sup d have been measured over the range 0.029 < x < 0.8 and 1.3 < Q sup 2 < 10 (GeV/c) sup 2 using deep inelastic scattering of polarized electrons from polarized ammonia and deuterated ammonia targets. Evaluation of the integral GAMMA sub 1 sup p = integral sub 0 sup 1 g sub 1 sup p (x, Q sup 2)dx at fixed Q sup 2 = 3 (GeV/c) sup 2 yields 0.127 +- 0.004 +- 0.010, in agreement with previous experiments, but well below the Ellis-Jaffe sum rule prediction of 0.160 +- 0.006. The integral GAMMA sub 1 sup d = integral sub 0 sup 1 g sub 1 sup d (x,Q sup 2)dx also evaluated at fixed Q sup 2 = 3 (GeV/c) sup 2 gives 0.041 +- 0.004 +- 0.004, again below the Ellis-Jaffe sum rule prediction of 0.068 +- 0.005. From g sub 1 sup p and g sub 1 sup d , the neutron structure function g sub 1 sup n can be computed with GAMMA sub 1 sup n measured as -0....

Band, H R

2003-01-01

350

Precision measurement of the neutron spin dependent structure functions  

International Nuclear Information System (INIS)

In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g1n (x, Q2) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized 3He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 ? x ? 0.7 with an average Q2 of 5 GeV2. The author reports the integral of the spin dependent structure function in the measured range to be ?0.0140.7 dx g1n(x, 5 GeV2) = -0.036 ± 0.004(stat.) ± 0.005(syst.). The author observes relatively large values of g1n at low x that call into question the reliability of data extrapolation to x ? 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g1p and g1n paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q2 = 5 GeV2

1997-01-01

351

Dressing two nucleons at the same time  

International Nuclear Information System (INIS)

At intermediate energies, the interaction of two nucleons with pions is often described in terms of nonrelativistic time-ordered perturbation theory. The field theory is usually further simplified by restricting the Hilbert space to states having some maximum number of pions. One outstanding difficulty with such approaches is an inconsistent treatment of the dressed two-nucleon propagator. In the NN-?NN model, for example, states can have at mos t one pion, so that only one of the nucleons is allowed to undergo dressing at any one time. Thus each nucleon cannot obtain its full dressing and this leads to problems of wave function normalization. We have found a way to dress both nucleons at the same time, where each nucleon retains its full dressing. The method, involving a convolution integral, determines the full two-nucleon dressed propagator in a practical but exact way. Numerical calculations have been performed using a model of the ?N interaction in the one-pion approximation. We find a significant difference between the fully dressed two-nucleon propagator and the different-time propagator as used in NN-?NN models.

1993-01-01

352

High energy electron scattering on 6Li and 12C as an incoherent superposition of single nucleon processes  

International Nuclear Information System (INIS)

High energy electro-excitation cross sections on 6Li and 12C in the region of the first nucleon resonance are compared with calculations in the impulse approximation. It is shown that the 6Li and 12C cross sections can be reproduced by an incoherent superposition of nucleon structure functions for 0.2 2 2 and primary energies in the GeV range. (orig.)

1979-01-01

353

One-nucleon transfer reactions induced by secondary beam of 11Be: study of the nuclear structure of the exotic nuclei 11Be and 10Li  

International Nuclear Information System (INIS)

[en] The structure of the neutron rich light nuclei 11Be and 10Li has been investigated by means of one nucleon transfer reactions. The experiments have been carried out at GANIL in inverse kinematics using 11Be secondary beams. The 11Be(p,d)10Be reaction bas been studied at 35.3 MeV/u. The 10Be ejectiles were analyzed by the spectrometer SPEG, and coincident deuterons were detected in the position sensitive silicon detector CHARISSA. Transfer cross sections to 0+1 and 2+1, states in 10Be were measured up to ?CM = 16 deg. and compared to DWBA and CRC predictions. The effects of neutron-cure couplings on reaction form factors have been studied by solving coupled equations in the framework of a vibrational model. It is shown that the rate of core excitation 10Be2+ in the 11Begs wave function is overestimated by a standard analysis with form factors given by the usual Separation Energy prescription. The former model predicts a rate of core excitation of 16% and leads to theoretical cross sections which are in good agreement with the experimental data. The aim of the 11Be(d,3He)10Li experiment, realized at 37 MeV/u, was to measure the distribution of the 2s neutron strength in the unbound nucleus 10Li. The energy spectrum was deduced from the 3He energy and angle measured by the silicon strip detector array MUST. An asymmetric peak is clearly observed near the threshold, with a maximum at -Sn = 130 keV. This constitutes a direct proof of the inversion of 2s and 1p1/2 shells in 10Li, which was until now a controversial question in spite of many experimental efforts. On the other band the analysis of the 11Be(d,t)10Be reaction studied in the same experiment confirms the results obtained in the 11Be(p,d)10Be reaction concerning the 11Begs structure. This work shows the interest and feasibility of studies of the shell properties of exotic nuclei using transfer reactions induced by radioactive beams and constitutes the beginning of a program devoted to this kind of experiment. (author)

2000-01-01

354

(p, n) reaction and the nucleon-nucleon force  

Energy Technology Data Exchange (ETDEWEB)

The (p, n) charge exchange reaction is a powerful tool of nuclear structure physics, with spectroscopic characteristics that are closely related to the free interaction between nucleons. At proton energies in the range of 150-500 MeV, the interaction probes the spin dynamics in the charge exchange process and is particularly sensitive to nuclear pionic fields. At low energies, say less than 50 MeV bombarding energy, the reaction also probes the isovector density. An outstanding success of the reaction as a structural probe is the elucidation of the Gamow-Teller strength function in the nuclear excitation spectrum. However, the total strength found falls short of sum rule predictions by about 40%. Explanations of this quenching have been advanced along two lines, based on subnuclear degrees of freedom or on configuration mixing into high continuum states. Detailed theoretical arguments support the importance of configuration mixing. The subnuclear degrees of freedom may be comparable, but a decisive test is lacking.

Bertsch, G.F.; Esbensen, H.

1987-06-01

355

Short-Range Nucleon-Nucleon Correlations  

CERN Document Server

Valence-shell nucleon knock-out experiments, such as 12C(e,e'p)11B, measure less strength then is predicted by independent particle shell model calculations. The theoretical solution to this problem is to include the correlations between the nucleons in the nucleus in the calculations. Motivated by these results, many electron scattering experiments have tried to directly observe these correlations in order to gain new insight into the short-range part of the nucleon-nucleon potential. Unfortunately, many competing mechanisms can cause the same observable final-state as an initial-state correlation, making truly isolating the signal extremely challenging. This paper reviews the recent experimental evidence for short-range correlations, as well as explores the possibility that such correlations are responsible for the EMC effect in the 0.3 < xB < 0.7 deep inelastic scattering ratios.

Higinbotham, Douglas W

2010-01-01

356

Extraction of Neutron Structure Functions from (Semi)InclusiveDeuteron Data  

Science.gov (United States)

Structure functions parameterize fundamental information about the internal structure of the nucleon, and in the deep-inelastic region are given in terms of the longitudinal momentum distributions of the nucleons' quark and gluon constituents. Compared to the copious amount of proton structure function data, there is considerably less for the neutron, which is mainly derived from deuteron data. Extracting neutron structure functions from the deuteron results in ambiguities from the necessary nuclear corrections. Such ambiguities can be confronted using free neutron and proton and inclusive deuteron data. The Barely Off-shell Neutron Structure experiment (BoNuS) ran in experimental Hall B at Jefferson Lab in 2005 and provided a virtually free neutron target for the first time. Extraction of the free neutron structure functions has been performed via global fits to both the BoNuS and deuteron inclusive data, utilizing an existing fit to the free proton, within the framework of the weak binding approximation and utilizing various nuclear potentials. We will report on the results of this fitting effort and the consistency between neutron information from BoNuS and the impulse approximation.

Kalantarians, Narbe

2013-04-01

357

Nucleon pair approximation description of the low-lying structure of $^{108,109}$Te and $^{109}$I  

CERN Multimedia

The low-lying level schemes and electromagnetic transitions of $^{109}$Te, $^{109}$I, and the neighboring even-even nucleus $^{108}$Te, are calculated within the framework of the $SD$-pair approximation of the nuclear shell model. Good agreement is obtained between the calculated results and experimental data. The favored components of low-lying bands are discussed in the collective nucleon-pair subspace. The weak-coupling picture shown in these nuclei and its relationship with residual quadrupole-quadrupole interaction between valence protons and neutrons are analyzed.

Jiang, H; Lei, Y; Liotta, R; Wyss, R; Zhao, Y M

2013-01-01

358

Role of the nucleon virtual mass in quark distributions of nuclei  

International Nuclear Information System (INIS)

A simple model which allows explicit calculations of the nuclear structure function in terms of the nucleon structure function for the deuteron as well as heavier nuclei is proposed. The impulse approximation in the DIS which leads to the convolution form of the nuclear structure function is examined and forms the basis of the model. The nucleus is viewed as a bound state of nucleons in constant motion with virtual mass less than the mass of a free nucleon. The EMC effect is discussed in the context of the model. Quantitative agreement with the nuclear DIS data is obtained. It was found that most of the nucleus momentum fraction is carried by the nucleons while a small portion is carried by other constituents presumed to be responsible for binding. The momentum fraction of these binding constituents showed saturation behavior similar to that found for the Fermi momentum as the atomic mass number of the nucleus increases, thereby suggesting a relationship between the two. Comparison is made between the model and other possible EMC effect interpretations. Lastly, a decisive test for the convolution form in general and the nuclear virtual mass, in particular, is provided. As predicted by the model, the ratio of nuclear to nucleon Q2- moments are shown to be Q2-independent and the values of this ratio for various nuclei are given.

1988-01-01

359

Higgs boson production by high-energy lepton nucleon interactions  

International Nuclear Information System (INIS)

[en] The production rate of Higgs bosons in high-energy lepton-nucleon collisions is calculated. In the case in which a Higgs boson is produced off an internal line of a weak boson, a complete formula is given in terms of Q2 dependent structure functions together with a numerical estimate in the TeV region. An estimate of the cross section in also attempted when a Higgs boson is emitted from a heavy quark. (orig.)

1980-01-01

360

Report on the Spin Asymmetries of the Nucleon Experiment  

Science.gov (United States)

The Spin Asymmetries of the Nucleon Experiment (SANE) measured the proton spin structure function g2 in a range of Bjorken x, 0.3 lucite hodoscope and a large array of lead glass detectors. With a unique open geometry, a threshold gas Cherenkov detector allowed BETA to cleanly identify electrons for this inclusive experiment. We will discuss the performance of BETA with an emphasis on the gas Cherenkov and present the current status of experimental analysis. )

Armstrong, Whitney

2010-02-01

 
 
 
 
361

Structure and function of claudins.  

UK PubMed Central (United Kingdom)

Claudins are tetraspan transmembrane proteins of tight junctions. They determine the barrier properties of this type of cell-cell contact existing between the plasma membranes of two neighbouring cells, such as occurring in endothelia or epithelia. Claudins can completely tighten the paracellular cleft for solutes, and they can form paracellular ion pores. It is assumed that the extracellular loops specify these claudin functions. It is hypothesised that the larger first extracellular loop is critical for determining the paracellular tightness and the selective ion permeability. The shorter second extracellular loop may cause narrowing of the paracellular cleft and have a holding function between the opposing cell membranes. Sequence analysis of claudins has led to differentiation into two groups, designated as classic claudins (1-10, 14, 15, 17, 19) and non-classic claudins (11-13, 16, 18, 20-24), according to their degree of sequence similarity. This is also reflected in the derived sequence-structure function relationships for extracellular loops 1 and 2. The concepts evolved from these findings and first tentative molecular models for homophilic interactions may explain the different functional contribution of the two extracellular loops at tight junctions.

Krause G; Winkler L; Mueller SL; Haseloff RF; Piontek J; Blasig IE

2008-03-01

362

Instantons and Nucleon Magnetism  

CERN Document Server

We construct improved QCD sum rules for the nucleon magnetic moments by implementing direct-instanton contributions to the operator product expansion of the nucleon correlator in a magnetic background field. The instanton contributions are found to affect only those sum rules which had previously been considered unstable. The new sum rules show a high degree of stability and reproduce the experimental values of the nucleon magnetic moments for values of the magnetic quark condensate susceptibility which are consistent with other estimates.

Forkel, H

2000-01-01

363

Nucleon in Nuclear Matter  

Directory of Open Access Journals (Sweden)

Full Text Available The modification of the properties of nucleon in nuclear medium has been investigated in the context of flux tube model. A nucleon has been described as diquark-quark system connected by flux tube and quasi particle diquark model has been used to describe the diquak constituting the nucleon. The modification of incompressiblity, the Roper resonance etc in the nuclear medium have been investigated. The results are compared with recent experimental and theoretical predictions. Some interesting observations are made.

Aparajita Bhattacharya; A. Sagari; B. Chakrabarti; A. Chandra

2011-01-01

364

K$^+$-nucleon interaction  

CERN Multimedia

The Born approximation to the quark-gluon-exchange mechanism for K$^+$N scattering is used as a starting point to generate a potential for this system. The valence quark wave function of the nucleon is generalized from a single Gaussian to a sum of Gaussians in order to have a more flexible representation than previous work. We obtain a potential derived from a valence density given by lattice calculations. By comparing with a recent amplitude analysis it is found that the strength of the quark-gluon based potential needs to be increased by a factor of order 2-4 relative to the normalization given by more traditional values of the governing parameters. The method is used to estimate the change in effective K$^+$N amplitudes which would result from changes in the valence quark distributions or strength of the interaction which might arise from nuclear medium effects in K$^+$ scattering from nuclei.

Gibbs, W R

2008-01-01

365

Effect of Excess Target Nucleons on The Main Features of Excitation Functions For Some Proton Induced Reactions Depending on Alice-IPPE Calculations  

International Nuclear Information System (INIS)

Proton induced nuclear reactions at low proton energies are commonly used for production of radioactive isotopes which are important for many different applications. The production yield depends on excitation function features for the used nuclear reaction. In this work the excitation functions for more than 80 protons induced nuclear reactions were constructed using the ALICE-IPPE code which depends on the pre equilibrium model. Four groups of different isotopes were chosen to study the effect of the excess target neutrons on the threshold energy (Ethr), maximum reaction cross section (?max) and the energy at maximum cross section (Emax). The selected groups were the natural isotopes of Ti, Cr, Fe and Ni. For the study of the effect of excess target protons on the same previous parameters, the excitation functions for the reactions on the isotones group 54Cr, 55Mn, 56Fe and 58Ni were performed at the same proton energy range. In order to understand the effect of the neutron to proton ratio on the previously mentioned parameters, proton reactions on the group of isobars 50Ti, 50V and 50Cr had been studied. In each case three protons induced reactions were undertaken, manly (p,n), (p,2n) and (p,3n). Each of the three previously mentioned parameters for each reaction were tabulated as a function of the excess number of nucleons and curve fit were constructed in order to get some phenomenological formulae for the behavior of these parameters

2010-01-01

366

Study of the compressibility of the nucleon  

Energy Technology Data Exchange (ETDEWEB)

A brief discussion of the theoretical and experimental situation in baryon spectroscopy is given. Then, the radial structure is discussed, related to the ground state form factors and the compressibility. The compressibility derived from experimental data is compared with results from different nucleon models. From the study of the Roper resonance in nuclei information on the dynamical radius of the nucleon can be obtained. Experiments have been performed on deuteron and {sup 12}C which show no shift of the Roper resonance in these systems. This indicates no sizeable `swelling` or `shrinking` of the nucleon in the nuclear medium. (K.A.). 25 refs.

Morsch, P.H. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik]|[Laboratoire National Saturne, Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

1996-12-31

367

Study of the compressibility of the nucleon  

International Nuclear Information System (INIS)

A brief discussion of the theoretical and experimental situation in baryon spectroscopy is given. Then, the radial structure is discussed, related to the ground state form factors and the compressibility. The compressibility derived from experimental data is compared with results from different nucleon models. From the study of the Roper resonance in nuclei information on the dynamical radius of the nucleon can be obtained. Experiments have been performed on deuteron and 12C which show no shift of the Roper resonance in these systems. This indicates no sizeable 'swelling' or 'shrinking' of the nucleon in the nuclear medium. (K.A.)

1996-01-01

368

Interaction of relativistic deuterons with nucleons  

International Nuclear Information System (INIS)

[en] The processes of the interaction of fast deuterons with nucleons dN -> pX, when the proton is scattered at a large angle in N-N c.m.s. are analyzed. There the wave function of a relativistic deuteron in dynamics of the light cone is used. It is shown, that as in the processes of the deuteron fragmentation type, it is necessary to take into account, the graphs of rescattering and absorption of the ?-meson by a deuteron nucleon, as well as a non-nucleon, quark, degree of freedom in the deuteron. The comparison of the theoretical calculations with the experimental data is performed

1988-01-01

369

Measurement of the neutron spin structure function---Test of the Bjorken sum rule  

Energy Technology Data Exchange (ETDEWEB)

As experiment to measure the neutron spin-dependent structure function g{sub 1}{sup n} (x) over a range in x from 0.04 to 0.7 and with Q{sup 2} > 1 (GeV/c){sup 2} is presented. The experiment consists of scattering a longitudinally polarized electron beam from the Stanford Linear Accelerator off a polarized {sup 3}He target and detecting scattered electrons in two magnetic spectrometers. The experiment will provide a critical test of the Bjorken sum rule and valuable information in understanding the nucleon spin structure and the violation of the Ellis-Jaffe sum rule. 3 figs., 1 tab.

Petratos, G.G.

1991-08-01

370

A study of nuclear effect in $F_3$ structure function in the deep inelastic $\  

CERN Multimedia

We study nuclear effect in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by taking into account Fermi motion, binding, target mass correction, shadowing and anti-shadowing corrections. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. Results for $F^A_3(x)$ have been compared with the results reported at NuTeV and also with some of the older experiments reported in the literature.

Athar, M Sajjad; Singh, S K; Vacas, M J Vicente

2009-01-01

371

Relativistic Fermi motion and nuclear structure functions  

Energy Technology Data Exchange (ETDEWEB)

We demonstrate that in the scaling regime for deep-inelastic structure functions, a model which accurately takes into account relativistic momentum smearing of nuclear structure functions explains the European Muon Collaboration effect.

Morley, P.D.; Schmidt, I.

1986-09-01

372

[GABAC receptors: structure and functions].  

UK PubMed Central (United Kingdom)

Data on the structure, localization, physiology and pharmacology of GABA(C) receptors are reviewed. Thece receptors belong to cys-loop receptors and consist of rho1-3 subunits representing pentamers with five subunits that form a chloride channel. They are found in both central nervous system and peripheral organs. The pentamer can be homomeric, consisting of five similar protomers (e.g., p1), or heteromeric (pseudo-homomeric), consisting of rho1 and rho2 subunits. Chloride channel function also depends on the GABA(C) receptor subunit composition. The activation of GABAc receptors is accompanied by a change in the permeability of plasmatic membranes for C1 ions, which is followed by depolarization (presynaptic inhibition) or hyperpolarization (postsynaptic inhibition). There are a great number of the allosteric modulators, agonists and antagonists of GABA(C) receptors.

Perfilova VN; Tiurenkov IN

2011-01-01

373

[GABAC receptors: structure and functions].  

Science.gov (United States)

Data on the structure, localization, physiology and pharmacology of GABA(C) receptors are reviewed. Thece receptors belong to cys-loop receptors and consist of rho1-3 subunits representing pentamers with five subunits that form a chloride channel. They are found in both central nervous system and peripheral organs. The pentamer can be homomeric, consisting of five similar protomers (e.g., p1), or heteromeric (pseudo-homomeric), consisting of rho1 and rho2 subunits. Chloride channel function also depends on the GABA(C) receptor subunit composition. The activation of GABAc receptors is accompanied by a change in the permeability of plasmatic membranes for C1 ions, which is followed by depolarization (presynaptic inhibition) or hyperpolarization (postsynaptic inhibition). There are a great number of the allosteric modulators, agonists and antagonists of GABA(C) receptors. PMID:21476276

Perfilova, V N; Tiurenkov, I N

2011-01-01

374

Structures and Functions of Oligosaccharins  

Energy Technology Data Exchange (ETDEWEB)

We have made considerable progress during the 2.5 year funding period just ending in our studies of the structures and functions of oligosaccharide signal molecules (oligosaccharins). We have emphasized studies of the enzymes that solubilize, process, and degrade oligosaccharins and of the proteins that inhibit those enzymes. We have been especially interested in elucidating how oligosaccharins and their processing enzymes participate in determining the outcome of challenges to plants by pathogenic microbes. We have studied, to a lesser extent, the roles of oligosaccharins in plant growth and development. Abstracts of papers describing results acquired with support from this grant that have been published, submitted, or in preparation are presented to summarize the progress made during the last two and one half years. The report highlights the most important contributions made in our oiigosaccharin research during this time period, and the corresponding abstract is referenced. Results of work in progress are described primarily in conjunction with our application for continued support.

Albersheim, Peter

1995-12-01

375

Precision measurement of the neutron spin dependent structure functions  

Energy Technology Data Exchange (ETDEWEB)

In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g{sub 1}{sup n} (x, Q{sup 2}) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized {sup 3}He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 {le} x {le} 0.7 with an average Q{sup 2} of 5 GeV{sup 2}. The author reports the integral of the spin dependent structure function in the measured range to be {integral}{sub 0.014}{sup 0.7} dx g{sub 1}{sup n}(x, 5 GeV{sup 2}) = {minus}0.036 {+-} 0.004(stat.) {+-} 0.005(syst.). The author observes relatively large values of g{sub 1}{sup n} at low x that call into question the reliability of data extrapolation to x {r_arrow} 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g{sub 1}{sup p} and g{sub 1}{sup n} paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q{sup 2} = 5 GeV{sup 2}, determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule.

Kolomensky, Y.G.

1997-02-01

376

[Laminin: biosynthesis, structure and functions  

UK PubMed Central (United Kingdom)

Biosynthesized by epithelial, endodermal and Swann type cells, laminin (Lam) is a cross shaped multifunctional glycoprotein formed by the multimeric assembly of subunits which result from the activation of several genes. In vivo, depending on its location, because of its adhesive properties and multivalent affinities, Lam is in association as a part of supramolecular complexes together with compounds of the plasma, the basement membrane and the cell coat. In the basement membrane (MB) Lam has structural and functional roles. It may also be adsorbed on the cell coat or secreted. It is interacting with epithelial cells by the way of a plasma membrane receptor and has a role to play in cellular differentiation and proliferation. Lam is a molecular link of epithelial cells to MB. These features implicate the molecule in organogenesis, embryogenesis and post-traumatic healing. As a structural component of MB and as an attachment factor, Lam is involved: 1 in tumoral invasion which allows metastatic spreading, 2 in homing because metastatic cell display an increased receptivity to the molecule. The study of Lam expression, Lam receptivity and their factors of control should lead to a better understanding of the biochemical and molecular basis of differentiation, embryogenesis, organogenesis and metastasis.

Lissitzky JC; Kopp F; Charpin C; Chiarotti Y; Bignon C; Martin PM

1986-10-01

377

Deep inelastic lepton-nucleon scattering  

Energy Technology Data Exchange (ETDEWEB)

Experiments on deep inelastic scattering have demonstrated the validity of the electroweak theory and the quark structure of nucleons. Experiments are in the process of testing the predictions of QCD. The fundamental Bjorken sum rule has not yet been tested, but the recent measurement by EMC may well lead to a new understanding of the nucleon spin among the constituents. Neutrino experiments will have to reach a new level of precision to distinguish between competing theoretical models.(AIP)

Mishra, S.R.; Sciulli, F. (Nevis Laboratory, Columbia University, Irvington, New York 10533 (US))

1989-01-01

378

3He and 3H polarized structure functions, using the constituent quark model  

International Nuclear Information System (INIS)

We calculate polarized structure functions for 3He and 3H, using the convolution of the light cone momentum distribution with the polarized structure of the proton and neutron. The polarized structure function of the nucleon is computed using the constituent quark model. Hypergeometric orthogonal polynomials are employed to extract the unknown parameters in this phenomenological approach. These hypergeometric polynomials are placed at the third level of Askey scheme with two free parameters. The results obtained for the polarized nuclear structure functions and the ratio of the Bjorken sum rule for proton-neutron system to 3He-3H system are in good agreement with the available experimental data and some theoretical models. To improve the validity of the model at low x-values, the nuclear shadowing, antishadowing and ?-resonance effects are also considered.

2009-12-15

379

{sup 3}He and {sup 3}H polarized structure functions, using the constituent quark model  

Energy Technology Data Exchange (ETDEWEB)

We calculate polarized structure functions for {sup 3}He and {sup 3}H, using the convolution of the light cone momentum distribution with the polarized structure of the proton and neutron. The polarized structure function of the nucleon is computed using the constituent quark model. Hypergeometric orthogonal polynomials are employed to extract the unknown parameters in this phenomenological approach. These hypergeometric polynomials are placed at the third level of Askey scheme with two free parameters. The results obtained for the polarized nuclear structure functions and the ratio of the Bjorken sum rule for proton-neutron system to {sup 3}He-{sup 3}H system are in good agreement with the available experimental data and some theoretical models. To improve the validity of the model at low x-values, the nuclear shadowing, antishadowing and DELTA-resonance effects are also considered.

Yazdanpanah, M.M., E-mail: Myazdan@mail.uk.ac.i [Physics Department, Kerman Shahid Bahonar University, Kerman (Iran, Islamic Republic of); School of Particles and Accelerators, IPM (Institute for Studies in Theoretical Physics and Mathematics), PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Mirjalili, A., E-mail: Mirjalili@ipm.i [Physics Department, Yazd University, 89195-741, Yazd (Iran, Islamic Republic of); School of Particles and Accelerators, IPM (Institute for Studies in Theoretical Physics and Mathematics), PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Tehrani, S. Atashbar, E-mail: Atashbar@ipm.i [School of Particles and Accelerators, IPM (Institute for Studies in Theoretical Physics and Mathematics), PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Taghavi-Shahri, F., E-mail: F_Taghavi@mail.ipm.i [School of Particles and Accelerators, IPM (Institute for Studies in Theoretical Physics and Mathematics), PO Box 19395-5531, Tehran (Iran, Islamic Republic of)

2009-12-15

380

Nucleon Form Factors  

Energy Technology Data Exchange (ETDEWEB)

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.

Kees de Jager

2002-10-01

 
 
 
 
381

Using Drell-Yan Processes to Probe Nucleon and Meson Structure Functions  

CERN Multimedia

We investigate how Drell-Yan processes can be used to measure the magnitude of flavor symmetry violation in the proton sea. We examine the utility of the following beams: protons, charged pions, and charged kaons. In each case we present an approximate expression for the Drell-Yan asymmetry. Using currently available parton distributions, we locate those kinematic regions which provide the greatest information on the quantity $\\bar{d}^p(x) - \\bar{u}^p(x)$. If sufficiently intense $K^+$ beams were available, they could provide an efficient measurement of this quantity. Finally we present and discuss sets of sum rules for the Drell-Yan processes.

Bhalerao, R S

1998-01-01

382

The role of strange and charm quarks in the nucleon spin structure function  

CERN Document Server

We perform an analysis of the relation between the factorization scale and the masses of the quarks in the calculation of the hard gluon coefficient in polarized deep inelastic scattering. Particular attention is paid to the role of strange and charm quarks at finite momentum transfer. It is found that for the momentum transfer of the present experiments, the contribution from the charm quark is significant.

Steffens, F M

1996-01-01

383

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.

1978-08-30

384

QCD sum rule for nucleon in nuclear matter  

International Nuclear Information System (INIS)

We consider the two-point function of nucleon current in nuclear matter and write a QCD sum rule to analyse the residue of the nucleon pole as a function of nuclear density. The nucleon self-energy needed for the sum rule is taken as input from calculations using phenomenological N N potential. Our result shows a decrease in the residue with increasing nuclear density, as is known to be the case with similar quantities. (orig.)

2010-01-01

385

QCD sum rule for nucleon in nuclear matter  

Energy Technology Data Exchange (ETDEWEB)

We consider the two-point function of nucleon current in nuclear matter and write a QCD sum rule to analyse the residue of the nucleon pole as a function of nuclear density. The nucleon self-energy needed for the sum rule is taken as input from calculations using phenomenological N N potential. Our result shows a decrease in the residue with increasing nuclear density, as is known to be the case with similar quantities. (orig.)

Mallik, S. [Saha Institute of Nuclear Physics, Theory Division, Kolkata (India); Sarkar, Sourav [Variable Energy Cyclotron Centre, Kolkata, 700064 (India)

2010-01-15

386

Collective properties of nucleons in the abnormal-parity states  

Energy Technology Data Exchange (ETDEWEB)

In the first part of this work, we study the quadrupole collective properties of N{sub a}=2, 4, 6, and 8 nucleons occupying the abnormal-parity intruder single-particle states with high angular momenta j{sub a}=(9/2), (11/2), (13/2), and (15/2). This study is essential for a detailed understanding of the contribution made by these nucleons to the quadrupole collectivity of the yrast states of deformed nuclei. The properties studied include (i) the distribution of the angular momenta J contained in the intrinsic state of N{sub a} particles in the |j{sub a}k{sub a}> states, (ii) the relationship between the quadrupole moment Q{sub 0}(j{sub a},N{sub a}) of such an intrinsic state and the maximum angular momentum J{sub max} contained in it, (iii) the complete set of reduced quadrupole matrix elements (J{sup '}||Q||J) for transitions between all the states |J> and |J{sup '}> projected from the intrinsic state, (iv) the B(E2:J{yields}J-2) values, (v) the transition moments Q{sub t}(J), and (vi) the spectroscopic quadrupole moment Q(J). We compare these properties with similar properties of an intrinsic state having SU(3) symmetry which contains the same set of angular momenta as contained in the intrinsic state of a particular number of nucleons in a specific j{sub a} configuration. In the second part, we use the input from the first part to study the collective properties of the coupled system of protons and neutrons in abnormal-parity states. We show that the SU(3)-like features observed for the individual groups of abnormal-parity nucleons become stronger for the coupled system. Finally, in the third part, we consider the yrast bands of well-deformed nuclei projected from their Nilsson intrinsic states of valence nucleons in a major shell. We specify the structure of the wave function of each projected yrast state |J> in terms of the nucleons in both normal- and abnormal-parity states. These wave functions can be used to determine the individual contributions of the nucleons in normal- and abnormal-parity states to any specific property of the yrast state. In particular, we calculate the transition moments Q{sub t}(J) of the entire yrast band of even-even {sup 160-166}Yb, {sup 156,158}Dy, {sup 232}Th, {sup 234}U, and {sup 236}U projected from their respective Nilsson intrinsic states. (c) 2000 The American Physical Society.

Bhatt, K. H. [Department of Physics and Astronomy, University of Mississippi, University, Mississippi 38677 (United States); Joint Institute for Heavy-Ion Research, Oak Ridge, Tennessee 37831 (United States); Kahane, S. [Nuclear Research Center-Negev, Beer-Sheva, (Israel); Raman, S. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2000-03-01

387

Neutral-current x-distributions in the neutrino-nucleon scattering  

International Nuclear Information System (INIS)

In this thesis the measurement of the x distribution of the structure functions for deep inelastic charged-current and neutral-current neutrino-nucleon interactions at the CERN 200 GeV narrow-band neutrino beam is described. (HSI).

1983-01-01

388

Production of Heavy Quarks and Antiquarks in Neutrino and Antineutrino-Nucleon Collisions.  

Science.gov (United States)

A study of rescaling effects of nucleon structure functions, in other words, the production rates of heavy quarks and antiquarks (c, c/sup -/ b, b/sup -/, t, t/sup -/) was made, having as the objective the comparison between two formulations for rescaling...

Y. A. Coutinho

1986-01-01

389

Summary of CDHS results on charged current in upsilon sup(-) -nucleon interactions  

International Nuclear Information System (INIS)

[en] This short review includes results on cross sections up to 300 GeV, a test of Callan - Gross relation, the determination of structure functions of the nucleon and the limit on right handed currents contribution. Conclusions from tests of QCD and non asymptotically free theories for strong interactions are presented. (author)

1982-01-01

390

Nucleon-nucleon interaction in the soliton bag model  

International Nuclear Information System (INIS)

In the framework of the Soliton Bag Model introduced by Friedberg and Lee we treat S-wave nucleon-nucleon scattering. Our system consists of six quarks and the nontopological soliton field which represents an average colorfree interaction between the quarks and yields their (relative) confinement. The dynamical problem is treated by means of the Generator coordinate Method (GCM) where the total wave function is the weighted sum over static configurations of prescribed bag deformation. The static configurations needed for the GCM ansatz are generated starting from a potential well of prescribed deformation wherein we solve the Dirac equation for the quarks. The single particle quark orbitals are properly coupled with respect to orbital, color, spin, and isospin quantum numbers to form a totally antisymmetric 6-quark state. A mean field solution for the soliton field is then calculated and turned into a quantum mechanical state by a coherent state approximation. Since these static configurations are only to be seen as wave function generators for the GCM no selfconsistency between quark and soliton solution is enforced. With these configurations we then evaluate the norm and Hamiltonian kernels appearing in the GCM treatment. The Hill-Wheeler integral equation for the weight functions is transformed into a Schroedinger-type differential equation by an expansion into symmetric moments of up to second order. This equation is brought into a form where we can identify the interaction potential unambiguously. We find an intermediate range attraction of about 120 MeV and no attraction in the vicinity of the spherically symmetric shape of the system, in contradiction to the naive adiabatic potentials widely used in quark models for the nucleon-nucleon interaction up to now. (orig./HSI).

1985-01-01

391

The E142 SLAC experiment: measurement of the neutron gn1(x) spin structure function  

International Nuclear Information System (INIS)

This thesis describes the E142 experiment which has been carried out at the Stanford Linear Accelerator (SLAC), USA, from October to December 1992. This experiment of polarized inelastic scattering of a 22.6 GeV electron beam on a polarized helium 3 target has allowed the first measurement of the neutron gn1(x) spin structure function. The knowledge of this structure function gives informations on the nucleon spin structure. On the other hand, the gn1(x) structure function integral value on the 02 mean value of 2 GeV2 after some extrapolations. This value is at about two standard deviations away from the theoretical predictions of the Ellis-Jaffe rule. Thanks to the existing experimental results for the proton (E143 experiment), the Bjorken sum rule has been precisely tested and is perfectly compatible with the theoretical value. The results have allowed to estimate the nucleon spin fraction carried by the quarks. (J.S.). 86 refs., 58 figs., 13 tabs.

1995-01-01

392

Off-shell properties of the Paris nucleon-nucleon potential and implications for few-body systems  

International Nuclear Information System (INIS)

[en] We investigate the half-off-shell properties for the Paris nucleon-nucleon potential and for a separable representation of it. Deuteron bound-state and scattering wave functions as well as Noyes-Kowalski functions are considered. Essential features with respect to elastic electron-deuteron and nucleon-deuteron scattering are discussed. We find that some polarization observables of these processes dismiss certain off-shell behaviours encountered, for instance, in various phenomenological separable potentials

1984-01-01

393

Universality in low energy states: from few-atoms to few-nucleons  

CERN Multimedia

We investigate universal behavior in elastic atom-dimer scattering below the dimer breakup threshold calculating the atom-dimer effective-range function $ak\\cot\\delta$. We compare our results with the universal zero-range form deduced by Efimov, $ak\\cot\\delta=c_1(ka)+c_2(ka)\\cot[s_0\\ln(a\\kappa_*)+\\phi(ka)]$, for different values of the two-body scattering length $a$ and of the three-body parameter $\\kappa_*$. We observe a good agreement introducing a particular type of finite-range corrections. Furthermore, we show that the same parameterization describes a very different system: nucleon-deuteron scattering below the deuteron breakup threshold. Our analysis reveals a universal behavior that ranges from few-atom systems to few-nucleon systems, and clarifies the nature of the pole structure in the effective-range function of nucleon-deuteron scattering.

Kievsky, A

2013-01-01

394

Structure functions for light nuclei  

CERN Multimedia

We discuss the nuclear EMC effect with particular emphasis on recent data and our predictions for light nuclei including the deuteron (D), 3He, 4He, 9Be, 12C and 14N. In order to verify the consistency of the available data, we calculate the \\chi^2 deviation between different data sets. We find a good agreement among measurements from the NMC, SLAC E139, and HERMES experiments. However, our analysis indicates an overall normalization offset of about 2% in the data from the recent JLab E03103 experiment with respect to previous data for nuclei heavier than 3He. We also discuss the extraction of the neutron/proton structure function ratio F2n/F2p from the nuclear ratios 3He/D and D/p. Our results show that the JLab E03103 data on 3He/D require a renormalization of about 3% in order to be consistent with the n/p ratio obtained from the NMC experiment. After such a renormalization, the JLab data are in a good agreement with the corresponding HERMES data on 3He. Finally, we present a detailed comparison between ou...

Kulagin, S A

2010-01-01

395

Structure functions from the NMC  

International Nuclear Information System (INIS)

[en] The New Muon Collaboration has measured deep inelastic muon scattering on hydrogen and deuterium at incident energies of 90 and 280 GeV. From the measured cross section ratios ?d/?p the difference of R, the ratio of longitudinally to transversely polarised virtual photon absorption cross sections, was obtained. Covering a range in ? from 0.01 to 0.3 at a typical Q2 of 9 GeV2 the results are compatible with zero. The structure functions F2p and F2d were extracted in a wide kinematic range: 0.00622. The comparison with previous experiments shows good agreement with the BCDMS and reanalysed SLAC data, while there is a clear discprepancy with the reanalysed EMC data. A next-to-leading order QCD analysis of the NMC data shows good agreement between data and theory. The quark and gluon distributions are extracted with good precision down to small values of ? for Q2>1 GeV2. Extrapolations to small ? of recent parton distributions are shown to disagree with the NMC results. (orig.)

1992-01-01

396

Gluon virtuality and heavy sea-quark contributions to the spin-dependent g{sub 1} structure function  

Energy Technology Data Exchange (ETDEWEB)

We analyze the quark mass dependence of photon gluon fusion in polarized deep inelastic scattering for both the intrinsic and extrinsic gluon distributions of the nucleon. We calculate the effective number of flavors for each of the heavy and light quark photon gluon fusion contributions to the first moment of the spin-dependent structure function g{sub 1}(x). {copyright} {ital 1999} {ital The American Physical Society}

Bass, S.D. [Max Planck Institut fuer Kernphysik, Postfach 103980, D-69029 Heidelberg (Germany); Brodsky, S.J. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (United States); Schmidt, I. [Departmento de Fisica, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile)

1999-08-01

397

Perturbative QCD study of the polarized structure function g{sub 1} at Next-to-Leading-Order  

Energy Technology Data Exchange (ETDEWEB)

A NLO perturbative study of all available data on polarized structure function g{sub 1}(x,Q{sup 2}) is presented. It is first explained how the Q{sup 2} evolution was performed using the DGLAP equations, which used with the present data, allow to constrain the behaviour of polarized parton distributions. Implications of such a study are discussed and important quantities are derived such as an estimation of the quark and gluon polarizations in the nucleon. (author) 18 refs.

Incerti, S. [Clermont-Ferrand-2 Univ., 63 - Aubiere (France). Lab. de Physique Corpusculaire; Sabatie, F. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee

1998-10-01

398

Nucleon form factors, generalized parton distributions and quark angular momentum  

CERN Multimedia

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 mu = 2 GeV to be J_v^u = 0.230 +0.009 -0.024 and J_v^d = -0.004 +0.010 -0.016.

Diehl, Markus

2013-01-01

399

Nucleon form factors, generalized parton distributions and quark angular momentum  

Energy Technology Data Exchange (ETDEWEB)

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 {mu}=2 GeV to be J{sup u}{sub v}=0.230{sup +0.009}{sub -0.024} and J{sup d}{sub v}=-0.004{sup +0.010}{sub -0.016}.

Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kroll, Peter [Bergische Univ., Wuppertal (Germany). Fachbereich Physik; Regensburg Univ. (Germany). Institut fuer Theoretische Physik

2013-02-15

400

Design of an experiment on nucleon-nucleon correlation  

International Nuclear Information System (INIS)

The one-nucleon exchange (ONE) reaction experiment was scheduled from 18th to 24th, October 2004 at the RIKEN Accelerator Research Facility (RARF). The experiment is proposed to study nucleon-nucleon correlation in di-nucleon configuration of cluster nuclei 6He, 6Li. To optimize the experimental setup, a detail simulation has been performed under an assumption of the ONE reaction which is expected to be sensitive to the relative momentum distribution of the di-nucleons. (author)

2005-01-01

 
 
 
 
401

Third-order QCD corrections to the charged-current structure function F3  

International Nuclear Information System (INIS)

We compute the coefficient function for the charge-averaged W±-exchange structure function F3 in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling ?s and of 1/Q2 power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F3 in powers of ?s is stable at all values of x relevant to measurements at high scales Q2. At small x the third-order coefficient function is dominated by diagrams with the colour structure dabcdabc not present at lower orders. At large x the coefficient function for F3 is identical to that of F1 up to terms vanishing for x?1. (orig.)

2008-01-01

402

The study of the cumulative effect in meson and nucleonic system production  

International Nuclear Information System (INIS)

Relativistic nuclear reactions with protons (deuterons) 8.0 GeV/c in the limiting fraamentation region (4-momentum transfer Q >= 1 GeV), with the particle production energy exceeding the nucleon-nucleon kinematical limit, were studied. The data acqusition, processing and analysis methods are presented along with experimental results like enerqy, angular distributions and A-mass dependence, carried out on DISC-2 Spectrometer (Dubna). Scale invariance character of the meson production, tells about local, pointlike interactions, interpreted like violent quark collisions. The quark structure functions of nuclei was obtained, proving the existence of multiquark states in nuclei. (author).

1984-01-01

403

Deep inelastic lepton scattering on nuclei: operator product expansion and meson-nucleon theory  

International Nuclear Information System (INIS)

[en] A novel point of view on the x-rescaling model in lepton-nucleous deep inetic scattering is suggested. Using the operator product expansion method within the effective meson-nucleon theory, a rigorous consideration of the scattering on the deuteron is presented. It is demonstrated that with the contributions interpreter as the Fermi motion corrections, the x-rescaling idea is exactly reproduced. The diagrams of scattering of bound nucleons have also been computed numerically. An example of application of the method, viz. the problem of extraction of the neutron structure function from the combined proton-deuteron data, is considered. 26 refs.; 5 figs

1992-01-01

404

Local duality in spin structure functions g1(p) and g1(d)  

Energy Technology Data Exchange (ETDEWEB)

Inclusive double spin asymmetries obtained by scattering polarized electrons off polarized protons and deuterons have been analyzed to address the issue of quark hadron duality in the polarized spin structure functions gp 1 and gd 1. A polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the data. The resulting gp 1 and gd 1 were averaged over the nucleon resonance energy region (M

Yelena Prok

2006-02-01

405

Measurements of the longitudinal structure function and |Vcs| in the CCFR experiment  

International Nuclear Information System (INIS)

Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F2, xF3? , xF3anti ? and R(longitudinal) in the kinematic region 0.01 2 2. The new measurements of R in the x 2 dependence of R is compared with a QCD based fit to previous data. The CKM matrix element |V|cs is extracted from a combined analysis of xF3 and dimuon data.

1998-01-01

406

Target mass corrections for spin-dependent structure functions in collinear factorization  

Energy Technology Data Exchange (ETDEWEB)

We derive target mass corrections (TMC) for the spin-dependent nucleon g_1 and g_2 structure functions in collinear factorization at leading twist. The TMCs are found to be significant for g_1 at large x_B, even at relatively high Q^2 values, but largely cancel in the polarization asymmetry A_1. A comparison of TMCs obtained from collinear factorization and from the operator product expansion shows that at low Q^2 the corrections drive the proton A_1 in opposite directions.

Accardi, Alberto; Melnitchouk, Wolodymyr

2008-12-01

407

Target mass corrections for spin-dependent structure functions in collinear factorization  

CERN Multimedia

We derive target mass corrections (TMC) for the spin-dependent nucleon structure function g1 and polarization asymmetry A1 in collinear factorization at leading twist. The TMCs are found to be significant for g1 at large xB, even at relatively high Q^2 values, but largely cancel in A1. A comparison of TMCs obtained from collinear factorization and from the operator product expansion shows that at low Q^2 the corrections drive the proton A1 in opposite directions.

Accardi, A

2008-01-01

408

On the nucleon association theory in light nuclei  

International Nuclear Information System (INIS)

[en] A new approach to the problem of the association of nucleons in light nuclei is discussed. It is based on the assumption that the same nucleon can simultaneously be a part of several strongly correlated groups of nucleons (clusters). In the framework of this approach a uniform scheme is proposed to construct the ground state wave function of several light nuclei (42+ and H-

1975-01-01

409

Nucleon optical potential  

Energy Technology Data Exchange (ETDEWEB)

Contents: Phenomenological analyses -- The energy dependence of the real potential, The radial variation of the real potential, The imaginary potential; Nuclear matter calculations; The spin-orbit potential; The isospin potential; General features of the nucleon optical potential.

Hodgson, P.E.

1983-01-01

410

Gluon polarization in nucleon  

International Nuclear Information System (INIS)

In the context of the so-called valon model, we calculate (?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 (?g)/g in the measured kinematical region should not be interpreted as ?g being small. In fact, ?g itself at small x, and the first moment of the polarized gluon distribution in the nucleon, ?g(Q2), are large.

2010-07-12

411

From nuclei to nucleons  

International Nuclear Information System (INIS)

Some initial experiments in the intermediate energy region between 10 and 200 MeV/nucleon, which is largely unexplored and poorly understood is considered as regards some initial experiments in this energy region. Included are the emission of complex fragments, localization in heavy ion reactions, coincidence experiments between light and heavy fragments, and the emission of light particles in heavy ion collisions. Some initial results in the region between 20 and 100 MeV/nucleon are presented. 41 references.

1978-01-05

412

Sign-symmetry of temperature structure functions.  

UK PubMed Central (United Kingdom)

New scalar structure functions with different sign-symmetry properties are defined. These structure functions possess different scaling exponents even when their order is the same. Their scaling properties are investigated for second and third orders, using data from high-Reynolds-number atmospheric boundary layer. It is only when structure functions with disparate sign-symmetry properties are compared can the extended self-similarity detect two different scaling ranges that may exist, as in the example of convective turbulence.

Aivalis KG; Kurien S; Schumacher J; Sreenivasan KR

2004-06-01

413

Sign-symmetry of temperature structure functions.  

Science.gov (United States)

New scalar structure functions with different sign-symmetry properties are defined. These structure functions possess different scaling exponents even when their order is the same. Their scaling properties are investigated for second and third orders, using data from high-Reynolds-number atmospheric boundary layer. It is only when structure functions with disparate sign-symmetry properties are compared can the extended self-similarity detect two different scaling ranges that may exist, as in the example of convective turbulence. PMID:15244734

Aivalis, Konstantinos G; Kurien, Susan; Schumacher, Jörg; Sreenivasan, Katepalli R

2004-06-23

414

Momentum and angular characteristics of ?- mesons and protons produced in nucleus-nucleus interactions at 4.2 GeV/c per nucleon as functions of a target minimal mass  

International Nuclear Information System (INIS)

Momentum and angular characteristics of negative pions and of protons generated in nucleus-nucleus interactions at 4.2 GeV/c per nucleon are investigated as functions of a variable, characterizing the order of cumulativity. It is shown that the character of the dependence on the cumulative variable does not depend on the type of colliding nuclei and is similar for pions and protons

1984-01-01

415

Measurement of the structure functions g1p and g1n with the CLAS at Jefferson Lab  

International Nuclear Information System (INIS)

Inelastic scattering using polarized nucleon targets and polarized charged lepton beams allows the extraction of the structure functions g1 and g2 which provide information on the spin structure of the nucleon. A program designed to study such processes has been underway in Jefferson Lab since 1998. A polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the desired data. 3 billion events were accumulated during the first run, and over 23 billion events were accumulated during the second run. The measurements cover the resonance region with unprecedented detail and add significantly to the DIS data set at low to moderate Q2 and moderate to high x.

2003-06-20

416

Measurement of the structure functions g1(p) and g1(n) with the CLAS at Jefferson Lab  

Energy Technology Data Exchange (ETDEWEB)

Inelastic scattering using polarized nucleon targets and polarized lepton beams allows the extraction of the structure function g_1 and g_2 which provide information on the spin structure of the nucleon. A program designed to study such processes has been underway in Jefferson Lab since 1998. A polarized electron beam, solid polarized NH_3 and ND_3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the desired data. 3 billion events were accumulated during the first run, and over 23 billion events were accumulated during the second run. The measurements cover the resonance region with unprecedented detail and add significantly to the DIS data set at low to moderate Q^2 and moderate to high x.

Yelena Prok

2003-07-01

417

Measurement of the Structure Functions g1p and g1n with the CLAS at Jefferson Lab  

Energy Technology Data Exchange (ETDEWEB)

Inelastic scattering using polarized nucleon targets and polarized charged lepton beams allows the extraction of the structure functions g1 and g2 which provide information on the spin structure of the nucleon. A program designed to study such processes has been underway in Jefferson Lab since 1998. A polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the desired data. 3 billion events were accumulated during the first run, and over 23 billion events were accumulated during the second run. The measurements cover the resonance region with unprecedented detail and add significantly to the DIS data set at low to moderate Q2 and moderate to high x.

Yelena Prok

2003-06-01

418

Measurement of the structure functions g1(p) and g1(n) with the CLAS at Jefferson Lab  

International Nuclear Information System (INIS)

Inelastic scattering using polarized nucleon targets and polarized lepton beams allows the extraction of the structure function g 1 and g 2 which provide information on the spin structure of the nucleon. A program designed to study such processes has been underway in Jefferson Lab since 1998. A polarized electron beam, solid polarized NH3 and NO3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to collect the desired data. 3 billion events were accumulated during the first run, and over 23 billion events were accumulated during the second run. The measurements cover the resonance region with unprecedented detail and add significantly to the DIS data set at low to moderate Q2 and moderate to high x.

2003-01-01

419

A comparison of charged current cross-sections and structure functions for neutrino and antineutrino beams on hydrogen and neon  

International Nuclear Information System (INIS)

[en] Using BEBC equipped with a hydrogen-filled neon-surrounded track sensitive target, the charged current cross sections and structure functions of hydrogen and neon targets traversed by the same neutrinos and antineutrinos are compared directly. The measured total cross section ratios between hydrogen and neon allow precise total cross section values for hydrogen to be inferred. Using this normalisation, the ? and ?-bar hydrogen data are combined and the quark distributions in free nucleons, parametrised as functions of xi, are extracted. This free-nucleon parametrisation is then compared directly with the neon data in order to measure nuclear effects such as those recently reported by the EMC collaboration. Only small effects are seen, in excellent agreement with recent SLAC data in a more similar A and q2 range. (author)

1983-01-01

420

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)

1998-09-05

 
 
 
 
421

Symmetric nuclear matter with chiral three-nucleon forces in the self-consistent Green's functions approach  

CERN Document Server

We present calculations for symmetric nuclear matter using chiral nuclear interactions within the Self-Consistent Green's Functions approach in the ladder approximation. Three-body forces are included via effective one-body and two-body interactions, computed from an uncorrelated average over a third particle. We discuss the effect of the three-body forces on the total energy, computed with an extended Galitskii-Migdal-Koltun sum-rule, as well as on single-particle properties. Saturation properties are substantially improved when three-body forces are included, but there is still some underlying dependence on the renormalization scale.

Carbone, Arianna; Polls, Artur

2013-01-01

422

Symmetric nuclear matter with chiral three-nucleon forces in the self-consistent Green's functions approach  

Science.gov (United States)

We present calculations for symmetric nuclear matter using chiral nuclear interactions within the self-consistent Green's functions approach in the ladder approximation. Three-body forces are included via effective one-body and two-body interactions, computed from an uncorrelated average over a third particle. We discuss the effect of the three-body forces on the total energy, computed with an extended Galitskii-Migdal-Koltun sum-rule, as well as on single-particle properties. Saturation properties are substantially improved when three-body forces are included, but there is still some underlying dependence on the similarity renormalization group evolution scale.

Carbone, Arianna; Polls, Artur; Rios, Arnau

2013-10-01

423

Single particle analysis of (e,e') and the value of separated structure functions  

International Nuclear Information System (INIS)

We report a calculation of inclusive electron scattering from 40Ca in the quasielastic region where we use relativistic Hartree bound-state wave functions for the nucleons and use the same real potential for the final-state interaction which guarantees orthogonality of initial and final states, current conservation, and, hence, gauge invariance. This potential gives quite good agreement with the measured cross sections, especially for energy transfer above the quasielastic peak approaching the dip region; however, it still does not successfully reproduce the experimentally separated longitudinal and transverse structure functions. We use this simple model which gives a reasonable fit to the cross-section data to discuss possible problems involved in the experimental separation procedure, which might distort the extraction of the longitudinal structure function

1992-01-01

424

Radial Dependence of the Nucleon Effective Mass in  

Energy Technology Data Exchange (ETDEWEB)

The dynamic properties of the atomic nucleus depend strongly on correlations between the nucleons. We present a combined analysis of inelastic electron-scattering data and electron-induced proton knockout measurements in an effort to obtain phenomenological information on nucleon-nucleon correlations. Our results indicate that the ration of radial wave functions extracted from precise B(e,e') and B(e, e'p) measurements evolve from an interior depression for small Em, characteristic of short-range correlations, to a surface-peaked enhancement for larger Em, characteristic of long-range correlations. This observation can be interpreted in terms of the nucleon effective mass.

L.J. de Bever; Henk Blok; Ross Hicks; Kees de Jager; N. Kalantar-Nayestanaki; James Kelly; L. Lapikas; Rory Miskimen; D. Van Neck; Gerald Peterson; G. van der Steenhoven; H. de Vries

1998-05-04

425

Limited Asymmetry Dependence of Correlations from Single Nucleon Transfer  

Science.gov (United States)

Single nucleon pickup reactions were performed with a 18.1MeV/nucleon O14 beam on a deuterium target. Within the coupled reaction channel framework, the measured cross sections were compared to theoretical predictions and analyzed using both phenomenological and microscopic overlap functions. The missing strength due to correlations does not show significant dependence on the nucleon separation energy asymmetry over a wide range of 37 MeV, in contrast with nucleon removal data analyzed within the sudden-eikonal formalism.

Flavigny, F.; Gillibert, A.; Nalpas, L.; Obertelli, A.; Keeley, N.; Barbieri, C.; Beaumel, D.; Boissinot, S.; Burgunder, G.; Cipollone, A.; Corsi, A.; Gibelin, J.; Giron, S.; Guillot, J.; Hammache, F.; Lapoux, V.; Matta, A.; Pollacco, E. C.; Raabe, R.; Rejmund, M.; de Séreville, N.; Shrivastava, A.; Signoracci, A.; Utsuno, Y.

2013-03-01

426

Disgust: evolved function and structure.  

UK PubMed Central (United Kingdom)

Interest in and research on disgust has surged over the past few decades. The field, however, still lacks a coherent theoretical framework for understanding the evolved function or functions of disgust. Here we present such a framework, emphasizing 2 levels of analysis: that of evolved function and that of information processing. Although there is widespread agreement that disgust evolved to motivate the avoidance of contact with disease-causing organisms, there is no consensus about the functions disgust serves when evoked by acts unrelated to pathogen avoidance. Here we suggest that in addition to motivating pathogen avoidance, disgust evolved to regulate decisions in the domains of mate choice and morality. For each proposed evolved function, we posit distinct information processing systems that integrate function-relevant information and account for the trade-offs required of each disgust system. By refocusing the discussion of disgust on computational mechanisms, we recast prior theorizing on disgust into a framework that can generate new lines of empirical and theoretical inquiry.

Tybur JM; Lieberman D; Kurzban R; DeScioli P

2013-01-01

427

Brazilian relativistic O(q4) two-pion exchange nucleon-nucleon potential: parametrized version  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english In our recent works we derived a chiral O(q4) two-pion exchange nucleon-nucleon potential (TPEP) formulated in a relativistic baryon (RB) framework, expressed in terms of the so called low energy constants (LECs) and functions representing covariant loop integrations. In order to facilitate the use of the potential in nuclear applications, we present a parametrized version of our configuration space TPEP.

Rocha, Carlos A. da; Higa, Renato; Robilotta, Manoel R.

2007-03-01

428

A model for the pion structure function  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The pion structure function is investigated in a simple model, where pion and constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma*pi --> gamma*pi evaluated and related to the structure functions. It is shown that the introduction o...

Bissey, F.; Cudell, Jean-René; Cugnon, Joseph; Jaminon, Martine; Lansberg, Jean-Philippe; Stassart, Pierre

429

Eta Structure Function via Photo-production  

International Nuclear Information System (INIS)

By using isobar model and the latest data, the structure function of Eta particle is calculated in the process of photo-production. This calculation is carried out for photon energy range of 0.750-3 GeV. The variations of the structure function are given in terms of scattering angle for different incoming photon energy.

2008-04-21

430

Structure and functional properties of colloidal systems  

CERN Multimedia

Presents the connections between structure and functional aspects in colloid and interface science. This title describes techniques to functionalize colloids, characterization methods, the physical fundamentals of structure formation, diffusion dynamics, transport properties in equilibrium, and the physical fundamentals of nonequilibrium systems.

Hidalgo-Alvarez, Roque

2009-01-01

431

Quark Hadron duality tests on polarized structure functions using CLAS  

Energy Technology Data Exchange (ETDEWEB)

Inclusive electron-nucleon scattering data from Jefferson Lab's Hall B has been analyzed to test quark-hadron duality for the polarized structure function g1(x,Q{sup 2}) over a Q{sup 2} range from 0.2 to 3.5 GeV{sup 2}/c{sup 2}. Incident polarized electron beam energies of 1.6 and 5.7 GeV were scattered by polarized {sup 15}NH{sub 3} and {sup 15}ND{sub 3} targets. The measurements of g1(x,Q{sup 2}) in the resonance region appear to be equivalent to a fit of g1(x,Q{sup 2}) in the deep inelastic scattering region at high Q{sup 2}. A quantitative test comparing the ratio of first moment in the resonance region to the first moment in the deep inelastic region is consistent with unity when Q{sup 2} > 2.0 GeV{sup 2}/c{sup 2} but substantially departs from unity when Q{sup 2} < 1.0 GeV{sup 2}/c{sup 2}.

Tony Forest

2004-06-02

432

Quark Hadron duality tests on polarized structure functions using CLAS  

International Nuclear Information System (INIS)

Inclusive electron-nucleon scattering data from Jefferson Lab's Hall B has been analyzed to test quark-hadron duality for the polarized structure function g1(x,Q2) over a Q2 range from 0.2 to 3.5 GeV2/c2. Incident polarized electron beam energies of 1.6 and 5.7 GeV were scattered by polarized 15NH3 and 15ND3 targets. The measurements of g1(x,Q2) in the resonance region appear to be equivalent to a fit of g1(x,Q2) in the deep inelastic scattering region at high Q2. A quantitative test comparing the ratio of first moment in the resonance region to the first moment in the deep inelastic region is consistent with unity when Q2 > 2.0 GeV2/c2 but substantially departs from unity when Q2 2/c2

2004-01-01

433

Functional annotation strategy for protein structures  

Directory of Open Access Journals (Sweden)

Full Text Available Whole-genome sequencing projects are a major source of unknown function proteins. However, as predicting protein function from sequence remains a difficult task, research groups recently started to use 3D protein structures and structural models to bypass it. MED-SuMo compares protein surfaces analyzing the composition and spatial distribution of specific chemical groups (hydrogen bond donor, acceptor, positive, negative, aromatic, hydrophobic, guanidinium, hydroxyl, acyl and glycine). It is able to recognize proteins that have similar binding sites and thus, may perform similar functions. We present here a fine example which points out the interest of MED-SuMo approach for functional structural annotation.

Olivia Doppelt; Fabrice Moriaud; Aurélie Bornot; Alexandre G. de Brevern

2007-01-01

434

Pion-Nucleon coupling at finite temperature  

CERN Multimedia

The pion nucleon vertex function at finite temperature is studied in the framework of: (a) the thermal (linear) sigma model to leading (one-loop) order, and (b) a thermal QCD-Finite Energy Sum Rule. Results from both methods indicate that the strength of the pion-nucleon coupling decreases with increasing T, vanishing at a critical temperature. The associated mean-square radius is a monotonically increasing function of T, diverging at the critical temperature. This is interpreted as (analytical) evidence for the quark-gluon deconfinement phase transition.

Domínguez, C A; Loewe, M

1998-01-01

435

Nucleon QCD sum rules in nuclear matter including four-quark condensates  

CERN Multimedia

We calculate the nucleon parameters in nuclear matter using the QCD sum rules approach in Fermi gas approximation. Terms up to 1/q^2 in the operator product expansion (OPE) are taken into account. The higher moments of the nucleon structure functions are included. The complete set of the nucleon expectation values of the four-quark operators is employed. Earlier the lack of information on these values has been the main obstacle for the further development of the approach. We show that the four-quark condensates provide the corrections of the order 20% to the results obtained in the leading orders of the OPE. This is consistent with the assumption about the convergence of the OPE. The nucleon vector self-energy \\Sigma_v and the nucleon effective mass m^* are expressed in terms of the in-medium values of QCD condensates. The numerical results for these parameters at the saturation value of the density agree with those obtained by the methods of nuclear physics.

Drukarev, E G; Sadovnikova, V A; Gutsche, T; Faessler, A; Gutsche, Th.; Faessler, Amand

2004-01-01

436

Cell Membrane Structure and Function  

Science.gov (United States)

Students learn about the different structures that comprise cell membranes, fulfilling part of the Research and Revise stages of the legacy cycle. Students view online animations of cell membrane dynamics (links provided). Then they observe three teacher demonstrations that illustrate diffusion and osmosis concepts, as well as the effect of movement through a semi-permeable membrane using Lugolâs solution.

Vu Bioengineering Ret Program

437

Hippocampal asymmetry: differences in structures and functions.  

UK PubMed Central (United Kingdom)

The structural asymmetry of bilateral hippocampus in mammals has been well recognized. Recent findings highlighted the accompanying functional asymmetries, as well as the molecular differences of the hippocampus. The present paper summarized these recent advances in understanding the hippocampal asymmetries at molecular, circuit and functional levels. Additionally, the addition of new neurons to the hippocampal circuit during adulthood is asymmetrical. We conclude that these differences in molecules and structures of bilateral hippocampus determined the variances in functionality between the two sides.

Hou G; Yang X; Yuan TF

2013-03-01

438

QCD analysis of the proton structure function  

Energy Technology Data Exchange (ETDEWEB)

QCD describes the scaling violations of structure functions which strongly depend on the gluon distribution. Thus, a QCD analysis of the proton structure function allows to test perturbative QCD and to measure the gluon distribution function. An important question is down to which Q{sup 2} the DGLAP perturbation theory in ln(Q{sup 2}) holds and at which x the BFKL ln(1/x) terms become important. These issues are adduced in the paper. (author) 8 refs.

Naumann, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); H1 Collaboration

1996-12-31

439

QCD analysis of the proton structure function  

International Nuclear Information System (INIS)

QCD describes the scaling violations of structure functions which strongly depend on the gluon distribution. Thus, a QCD analysis of the proton structure function allows to test perturbative QCD and to measure the gluon distribution function. An important question is down to which Q2 the DGLAP perturbation theory in ln(Q2) holds and at which x the BFKL ln(1/x) terms become important. These issues are adduced in the paper. (author)

1996-01-01

440

Structure and function in flow networks  

CERN Multimedia

This Letter presents a unified approach for the fundamental relationship between structure and function in flow networks by solving analytically the voltages in a resistor network, transforming the network structure to an effective all-to-all topology, and then measuring the resultant flows. Moreover, it defines a way to study the structural resilience of the graph and to detect possible communities.

Rubido, Nicolás; Baptista, Murilo S

2013-01-01

 
 
 
 
441

The nucleon-nucleon potential in the chromodielectric soliton model  

Energy Technology Data Exchange (ETDEWEB)

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.

Koepf, W.; Wilets, L. [Washington Univ., Seattle, WA (United States). Dept. of Physics; Pepin, S.; Stancu, F. [Liege Univ. (Belgium). Inst. de Physique

1993-12-31

442

The three-nucleon system and off-shell constraints of the nucleon-nucleon interaction  

International Nuclear Information System (INIS)

It is shown that the most important off-shell constraints on the nucleon-nucleon interaction are obtained from those properties of the deuteron which can be experimentally measured. For phase equivalent potentials fitted to the experimental nucleon-nucleon scattering data (i.e. on-shell data) we also discuss the restriction imposed by our experimental knowledge of the three-nucleon system. It is shown that although charge symmetry imposes an effective off-shell constraint on the neutron-neutron and proton-proton interactions in the 1-So state, this constraint is rather ineffective in the three-nucleon system. The only quantities in the three-nucleon system sensitive to the off-shell properties of the nucleon-nucleon interaction are the binding energy and the doublet scattering length which are strongly correlated

1975-07-07

443

Electroproduction of ?+ at the threshold on the nucleon  

International Nuclear Information System (INIS)

The ?+ electroproduction near the threshold on the nucleon, with separation of transverse and longitudinal parts of cross sections is presented. Dependence of nucleon axial form factor, as a function of the virtual photon quadrimoment, can be deduced up to 20(fermi)-2. After a brief theoretical review, the experimental method is shown and problems raised by the high quadrimomenta conclude the article

1987-01-01

444

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, ? 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.)

2006-01-01

445

A Covariant model for the nucleon and the $\\Delta$  

CERN Multimedia

The covariant spectator formalism is used to model the nucleon and the $\\Delta$(1232) as a system of three constituent quarks with their own electromagnetic structure. The definition of the ``fixed-axis'' polarization states for the diquark emitted from the initial state vertex and absorbed into the final state vertex is discussed. The helicity sum over those states is evaluated and seen to be covariant. Using this approach, all four electromagnetic form factors of the nucleon, together with the {\\it magnetic} form factor, $G_M^*$, for the $\\gamma N \\to \\Delta$ transition, can be described using manifestly covariant nucleon and $\\Delta$ wave functions with {\\it zero} orbital angular momentum $L$, but a successful description of $G_M^*$ near $Q^2=0$ requires the addition of a pion cloud term not included in the class of valence quark models considered here. We also show that the pure $S$-wave model gives electric, $G_E^*$, and coulomb, $G^*_C$, transition form factors that are identically zero, showing that th...

Ramalho, G; Gross, Franz

2008-01-01

446

The spin dependent structure function g1 of the deuteron and the proton  

International Nuclear Information System (INIS)

This thesis presents a study on the spin structure of the nucleon, via deep inelastic scattering (DIS) of polarised nuons on polarised proton and deuterium targets. The work was done in the Spin Muon Collaboration (SMC) at CERN in Geneva. From the asymmetry in the scattering cross section for nucleon and lepton spins parallel and anti-parallel, one con determine the spin dependent structure function g1, which contains information on the quark and gluon spin distribution functions. The interpretation in the frame work of the quark parton model (QPM) of earlier results on g1p by the European Muon Collaboration (EMC), gave an indication that only a small fraction of the proton spin, compatible with zero, is carried by the spins of the constituent quarks. The SMC was set up to check this unexpected result with improved accuracy, and to combine measurements of g1p and g1d to test a fundamental sum rule in quantum chromodynamics (QCD), the Bjorken sum rule. (orig./WL).

1995-01-01

447

Changes in gastrointestinal tract function and structure in functional dyspepsia.  

UK PubMed Central (United Kingdom)

Functional dyspepsia is an extremely common disorder of gastrointestinal function. The disorder is thought to be heterogeneous, with different pathophysiological mechanisms underlying varied symptom patterns. A diversity of changes in gastrointestinal tract function and structure has been described in functional dyspepsia. These involve alterations in the stomach, such as impaired accommodation, delayed gastric emptying and hypersensitivity, and alterations in the duodenum, such as increased sensitivity to duodenal acid and/or lipids and low-grade inflammation. In this Review, we summarize all these abnormalities in an attempt to provide an integrated overview of the pathophysiological mechanisms in functional dyspepsia.

Vanheel H; Farré R

2013-03-01

448

[Structure and function of integrons].  

UK PubMed Central (United Kingdom)

Integrons are genetic elements known for their role in the acquisition and expression of genes conferring antibiotic resistance. Integrons have an integrase gene (intI), an attachment site (attI), into which individual resistance genes are inserted and a promotor sequence (Pant), allowing expression of resistance genes (cassette-associated genes), which do not have promotors. Integrase recognizes 59-be, a specific sequence in certain resistance genes, which is captured by recombination at the attI attachment site. The fragment intI - attI is highly conserved in all integrons and is called 59 -CS. Integrons have been classified according to the sequence of their integrase and the ones most frequently detected in isolated clinical strains belong to Class I. Class I integrons contain the 59 -CS region followed by gene cassettes in a variable region and finally, a conserved region known as 39 -CS containing two genes, the quaternary ammonium resistance gene (qacEDI) and the sulphonamide resistance gene (sul1); both genes are fixed in this structure. Accordingly, the structure of a Class 1 integron would be IntI - attI [R11 R21.] - qacED1 - sul1. Integrons are probably not mobile, but they are often found in transposons within conjunctive plasmids, which assures their mobility, as can be seen by their wide diffusion among bacteria.

Sabaté M; Prats G

2002-08-01

449

Proton and deuteron spin structure function measurements in the resonance region  

Energy Technology Data Exchange (ETDEWEB)

The RSS collaboration has measured the spin structure functions of the proton and the deuteron at Jefferson Lab using the Hall C HMS spectrometer, a polarized electron beam and a polarized solid target. The asymmetries A and A were measured in the region of the nucleon resonances (0.82 GeV < W < 1.98 GeV) at an average four momentum transfer of Q2 = 1.3 GeV2. The extracted spin structure functions and their kinematic dependence will make a significant contribution in the study of higher-twist effects and polarized duality tests. A description of the experiment and the latest findings of the analysis will be presented.

F.R. Wesselmann

2003-07-01

450

Measurement of the neutron F2 structure function via spectator tagging with CLAS  

CERN Multimedia

We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to < 100 MeV and their angles to < 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of x for 0.65 < Q2 < 4.52 GeV2, with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F2n/F2p at 0.2 < x < 0.8, essentially free of nuclear corrections.

Baillie, N; Zhang, J; Bosted, P; Bultmann, S; Christy, M E; Fenker, H; Griffioen, K A; Keppel, C E; Kuhn, S E; Melnitchouk, W; Tvaskis, V; Adhikari, K P; Adikaram, D; Aghasyan, M; Amaryan, M J; Anghinolfini, M; Arrington, J; Avakian, H; Baghdasaryan, H; Battaglieri, M; Biselli, A S; Branford, 5 D; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Cole, P L; Contalbrigo, M; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Dey, B; Djalali, C; Dodge, G; Domingo, J; Doughty, D; Dupre, R; Dutta, D; Ent, R; Egiyan, H; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Fradi, A; Gabrielyan, M Y; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Gohn, W; Golovatch, E; Gothe, R W; Graham, L; Guegan, B; Guidal, M; Guler, N; Guo, L; Hafidi, K; Heddle, D; Hicks, K; Holtrop, M; Hungerford, E; Hyde, C E; Ilieva, Y; Ireland, D G; Ispiryan, M; Isupov, E L; Jawalkar, S S; Jo, H S; Kalantarians, N; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; King, P M; Klein, A; Klein, F J; Klimenko, A; Kubarovsky, V; Kuleshov, S V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I J D; Mao, Y; Markov, N; McKinnon, B; Mineeva, T; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Ni, A; Niccolai, S; Niculescu, I; Niculescu, G; Osipenko, M; Ostrovidov, A I; Pappalardo, L; Park, K; Park, S; Pasyuk, E; Pereira, S Anefalos; Pisano, S; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Rossi, P; Sabatie, F; Saini, M S; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Sharabian, Y G; Sober, D I; Sokhan, D; Stepanyan, S; Stepanyan, S S; Stoler, P; Strauch, S; Taiuti, M; Tang, W; Ungaro, M; Vineyard, M F; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zana, L; Zhao, B

2011-01-01

451

Tear lipocalin: structure and function.  

Science.gov (United States)

Lipocalins are a family of diverse low molecular weight proteins that act extracellularly. They use multiple recognition properties that include 1) ligand binding to small hydrophobic molecules, 2) macromolecular complexation with other soluble macromolecules, and 3) binding to specific cell surface receptors to deliver cargo. Tear lipocalin (TLC) is a major protein in tears and has a large ligand-binding cavity that allows the lipocalin to bind an extensive and diverse set of lipophilic molecules. TLC can also bind to macromolecules, including the tear proteins lactoferin and lysozyme. The receptor to which TLC binds is termed tear lipocalin-interacting membrane receptor (LIMR). LIMR appears to work by endocytosis. TLC has a variety of suggested functions in tears, including regulation of tear viscosity, binding and release of lipids, endonuclease inactivation of viral DNA, binding of microbial siderophores (iron chelators used to deliver essential iron to bacteria), serving as a biomarker for dry eye, and possessing anti-inflammatory activity. Additional research is warranted to determine the actual functions of TLC in tears and the presence of its receptor on the ocular surface. PMID:21791187

Dartt, Darlene A

2011-07-01

452

Gluon Polarization In Nucleon  

CERN Document Server

In the context of the so-called valon model, we calculate $\\frac{\\delta g}{g}$ 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 $\\frac{\\delta g}{g}$ 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, $\\Delta g(Q^2)$, are large

Shahveh, Abolfazl; Arash, Firooz

2010-01-01

453

Gluon polarization in nucleon  

Energy Technology Data Exchange (ETDEWEB)

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.

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

454

Nucleon decay experiments  

International Nuclear Information System (INIS)

[en] As can be seen three experiments have recently either been reconstructed (KOLAR II) or significantly been improved (KAMIOKANDE II, IMB III). The total useful luminosity of the five experiments adds up to ?6,5 kty1, that is ?4x1633 nucleons (proton + neutrons) have been looked at for one year. From this year on KOLAR, IMB and Kamiokande are much improved and add luminosity at better sensitivity for some of the potential nucleon decay modes and in general with better background rejection. (orig./BBOE)

1986-01-01

455

Determination of the neutron spin structure function  

International Nuclear Information System (INIS)

New measurements of the neutron spin structure function, g1(x), made at SLAC are reported, using longitudinally polarized electrons on a polarized 3He target. The spin structure function of the neutron has been determined from x=0.03 to x=0.6 at an average Q2 of 2 (GeV/c)2, by measuring the asymmetry in deep inelastic scattering of polarized electrons from polarized 3He at energies from 19 to 26 GeV. The integral over the spin structure function has been calculated. (author) 16 refs., 3 figs., 1 tab

1993-01-01

456

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

1990-01-01

457

Lepton nucleon scattering  

International Nuclear Information System (INIS)

The author discusses the theoretical reasons for the study of deep inelastic scattering. In this connection he considers structure functions, hadronic final states, the production of new flavous, and weak interaction effects. (HSI)

1983-02-10

458

Neutrino scattering as a probe for the strange content of the nucleon  

CERN Multimedia

We consider different methods and observables which can be obtained by the measurement of neutrino scattering off nucleons and nuclei with the purpose of finding evidence for the strange form factors of the nucleon, which enter into structure of the nucleonic weak neutral current.

Alberico, W M

2006-01-01

459

Electron-nucleon scattering experiments in the GeV range  

International Nuclear Information System (INIS)

In the framework of this thesis a computer code systems was developed which describes the inclusive electron scattering on bound nucleons in the impact approximation. It could be shown that the structure functions for the quasi-free scattering can be represented as an incoherent superposition of the structure functions of the free processes. The structure functions of the free processes were determined from experimental cross sections. From the comparison of the calculations with electron scattering experiments on the nuclei 6Li, 9Be, 12C, 27Al, and 28Si in the kinematic range 0.0 22 and W

1980-01-01

460

Dipole rescattering and the nuclear structure function  

Energy Technology Data Exchange (ETDEWEB)

In the framework of the dipole model, we study the effects of the dipole multiple scatterings in a nuclear target and compute the nuclear structure function. We compare different unitarization schemes and confront our results with the E665 data.

Carvalho, F. [Depto de Ciencias Exatas e da Terra, Universidade Federal de Sao Paulo, SP (Brazil); Goncalves, V. P. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-900, Pelotas, RS (Brazil); Navarra, F. S.; Oliveira, E. G. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil)

2013-03-25

 
 
 
 
461

Brain Structure-function Couplings (FY11).  

Science.gov (United States)

In FY11, a collaborative team of researchers began a new Director's Strategic Initiative (DSI) to examine brain structure-function couplings. The effort aims to develop a multidisciplinary, multiscale understanding of the relationship between the brain's ...

A. Dagro J. Vettel R. Kraft S. Gordon S. Kerick

2012-01-01