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1

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

2

Diquarks and nucleon structure functions

International Nuclear Information System (INIS)

Formulae for structure functions of the deep-inelastic lepton-nucleon scattering are obtained through relativistic wave functions of systems composed of particles with spins 0, 1/2 and 1, 1/2. These wave functions are solutions of covariant two-particle single-time equations describing the nucleon as a system formed out of a quark and a diquark. Diquark is considered as a boson with the spin 0 and 1. The expressions for the nucleon structure functions are obtained by using the matrix elements of the current operator corresponding to the elastic scattering of the photon on a quark and on a diquark

3

International Nuclear Information System (INIS)

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.)

4

Nucleon Structure Functions and Nuclear DIS

Digital Repository Infrastructure Vision for European Research (DRIVER)

The nucleon structure study in nuclear deep inelastic scattering is considered. It is shown that nuclear data provide a new source of information about dynamics of parton distributions in the nucleon. An example of the neutron structure function extraction from the deuteron and proton data is considered. The limit $x\\to 1$ of the neutron to proton structure functions ratio is studied. A link between the deep inelastic scattering off the nucleon at high $x$ and elastic scatte...

Molochkov, A.

2004-01-01

5

Nucleon neutral-current structure functions

International Nuclear Information System (INIS)

The structure of the nucleon is studied by means of deep-inelastic neutrino-nucleon scattering at high energies through the weak neutral current. The neutrino-nucleon scattering events were observed in a 340-metric-ton fine-grained calorimeter exposed to a narrow-band (dichromatic) neutrino beam at Fermilab. The data sample after analysis cuts consists of 9200 charged-current and 3000 neutral-current neutrino and antineutrino events. The neutral-current valence and sea nucleon structure functions are extracted from the x distribution reconstructed from the measured angle and energy of the recoil-hadron shower and the incident narrow-band neutrino-beam energy. They are compared to those extracted from charged-current events analyzed as neutral-current events. It is shown that the nucleon structure is independent of the type of neutrino interaction, which confirms an important aspect of the standard model. The data are also used to determine the value of sin2?W=0.238±0.013±0.015±0.010 for a single-parameter fit, where the first error is from statistical sources, the second from experimental systematic errors, and the third from estimated theoretical errors

6

Phenomenological study of the nucleon structure functions

International Nuclear Information System (INIS)

This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F2) and polarized (g1) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F2 and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions gp,n,d and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends

7

Statistical model for the structure functions of the nucleon

International Nuclear Information System (INIS)

The author presents a model of the structure functions of the nucleon which he has been working on during the past year. The structure functions of the nucleon are measured experimentally in the deep inelastic scattering of leptons off nucleons. The notations he follows are standard. To be specific the author considers the leptons to be electrons or muons but it is obvious that also neutrinos or antinuetrinos can be considered. The relevant tensor W/sub ??/ is related to the Lorentz-covariant structure functions W/sub 1/ and W/sub 2/

8

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.)

9

Energy Technology Data Exchange (ETDEWEB)

This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F{sub 2}) and polarized (g{sub 1}) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F{sub 2} and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions g{sup p,n,d} and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends.

Bertini, M.

1995-05-12

10

International Nuclear Information System (INIS)

In the nuclear medium, there are the non-nucleonic components. The leak-out partons, which form some colour-singlet parton clusters, are the origin of the non-nucleonic components. Meanwhile, the small x partons become co-used by several nucleons because the partons' longitudinal size extends over more than one nucleon. The nucleon effective mass can be successfully used as the only free parameter to adjust the structure function ratios recently measured by NMC

11

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)

12

Nucleon structure functions from ??-Fe scattering at the Tevatron {au}

We present preliminary results for nucleon structure functions measured in high energy neutrino interactions. Included are new results for the Gross-Llewellyn Smith Sum Rule, ? 1/x xF3dx=2.66±0.03(stat)±0.08(syst), the ratio of cross-sections, ??¯/??=0.511±0.002(stat)±0.005(syst), and an analysis of the Q2 evolution of xF3.

Quintas, P. Z.; Bachmann, K. T.; Blair, R. E.; Foudas, C.; King, B. J.; Lefmann, W. C.; Leung, W. C.; Mishra, S. R.; Oltman, E.; Rabinowitz, S. A.; Sciulli, F. J.; Shaevitz, M. H.; Seligman, W. G.; Smith, W. H.; Merritt, F. S.; Oreglia, M. J.; Schumm, B. A.; Bernstein, R. H.; Borcherding, M. J.; Fisk, H. E.; Lamm, M. J.; Schellman, H.; Marsh, W.; Merritt, K. W. B.; Yovanovitch, D. D.; Bodek, A.; Budd, H. S.; de Barbaro, P.; Sakumoto, W. K.

1992-01-01

13

Polarized structure functions of the nucleon in the resonance region

Energy Technology Data Exchange (ETDEWEB)

Aspects of the spin structure functions of proton and neutrons at low mentum 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 A{sub 1}{sup 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.

1994-04-01

14

Nuclear effects in F_3 structure function of nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 phenomenologic...

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

2007-01-01

15

Nuclear effects in F_3 structure function of nucleon

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

16

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

17

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

International Nuclear Information System (INIS)

Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function, F2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects. (orig.)

18

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

19

Nucleon spin structure functions from HERMES: The first year

International Nuclear Information System (INIS)

HERMES, HERA Measurement of Spin, is a second generation exper to study the spin structure of the nucleon by using polarized internal gas targets in the HERA 28 GeV electron storage ring. Scattered positrons and coincident hadrons are detected in an open geometry spectrometer which includes particle identification. Inclusive data with polarized 3He give the spin structure function gn1(x) and the Ellis-Jaffe integral RR? = ?01 gn1(x)dx for the neutron. The semi-inclusive spin asymmetries are a unique and sensitive probe of the flavor dependence of quark helicity distributions and properties of the quark sea. Data taken in 1995 with unpolarized hydrogen and deuterium targets provide measurements of the flavor distributions of sea and valence quarks. In a preliminary analysis, ?n1 = -0.032±0. 013stat. ± O.017syst. is obtained at Q2 = 3(GeV/c)2 for the Ellis-Jaffe integral

20

Chiral Quark Soliton Model and Nucleon Spin Structure Functions

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

21

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

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

22

Structure functions of the nucleon in a statistical model

International Nuclear Information System (INIS)

Deep inelastic scattering is considered in a statistical model of the nucleon. This incorporates certain features which are absent in the standard parton model such as quantum statistical correlations which play a role in the propagation of particles when considering Feynman diagrams containing internal lines. The inclusion of the O(?s) corrections in our numerical calculations allows a good fit to the data for x ? 0.25. The fit corresponds to values of temperature and chemical potential of approximately T = 0.067 GeV and ? = 0.133 GeV. The latter values of parameters, however, give rise, for all x, to a large value for R = ?L/?T. Even when taking into account that all measurements of R suffer from large experimental errors due to the weak dependence of the deep inelastic cross section for charged leptons on R, the size of the discrepancy remains unacceptable. This indicates a shortcoming of the statistical model in its present form to reproduce the structure function of the proton. (orig.)

23

Measurement of the nucleon structure function using high energy muons

International Nuclear Information System (INIS)

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

24

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

25

Effect of bound nucleon internal structure change on nuclear structure functions

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-$x$ ($x \\agt 0.85$) relative to those in a free nucleon. This implies that a part of the enhancement observed in the nuclear structure function $F_2$ (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 are different. The former [latter] is enhanced [quenched] in the region $0.8 \\alt x \\alt 0.9$ [$0.7 \\alt x \\alt 0.85$] 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.

Tsushima, K; Steffens, F M

2005-01-01

26

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.

27

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

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.

Zamani, F.

2010-07-01

28

Structure Functions of the Nucleon in a Covariant Scalar Spectator Model

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nucleon structure functions, as measured in deep-inelastic lepton scattering, are studied within a covariant scalar diquark spectator model. Regarding the nucleon as an approximate two-body bound state of a quark and diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the solutions of the BSE.

Kusaka, K.; Piller, G.; Thomas, A. W.; Williams, A. G.

1996-01-01

29

Structure functions of the nucleon in a covariant scalar spectator model

International Nuclear Information System (INIS)

Nucleon structure functions, as measured in deep-inelastic lepton scattering, are studied within a covariant scalar diquark spectator model. Regarding the nucleon as an approximate two-body bound state of a quark and diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the solutions of the BSE. 3 refs., 6 figs

30

Structure functions of the nucleon in a covariant scalar spectator model

Nucleon structure functions, as measured in deep-inelastic lepton scattering, are studied within a covariant scalar diquark spectator model. Regarding the nucleon as an approximate two-body bound state of a quark and diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the solutions of the BSE.

Kusaka, K; Thomas, A W; Williams, A G

1996-01-01

31

Bloom-Gilman duality of the nucleon structure function and the elastic peak contribution

Digital Repository Infrastructure Vision for European Research (DRIVER)

The occurrence of the Bloom-Gilman duality in the nucleon structure function is investigated by analyzing the Q**2-behavior of low-order moments, both including and excluding the contribution arising from the nucleon elastic peak. The Natchmann definition of the moments has been adopted in order to cancel out target-mass effects. It is shown that the onset of the Bloom-Gilman duality occurs around Q**2 ~ 2 (GeV/c)**2 if only the inelastic part of the nucleon structure functi...

Ricco, G.; Anghinolfi, M.; Ripani, M.; Taiuti, M.; Simula, S.

1999-01-01

32

Bloom-Gilman duality of the nucleon structure function and the elastic peak contribution

International Nuclear Information System (INIS)

The occurrence of the Bloom-Gilman duality in the nucleon structure function is investigated by analyzing the Q2-behaviour of low-order moments, both including and excluding the contribution arising from the nucleon elastic peak. The Natchmann definition of the moments has been adopted in order to cancel out target-mass effects. It is shown that the onset of the Bloom-Gilman duality occurs around Q2 ? 2 (GeV/c)2 if only the inelastic part of the nucleon structure function is considered, whereas the inclusion of the nucleon elastic peak contribution leads to remarkable violations of the Bloom-Gilman duality. Refs. 6, fig. 1 (author)

33

Charged current neutrino and antineutrino interactions and nucleon structure functions

International Nuclear Information System (INIS)

Final results are presented for studies, carried out by the HPWFRO-E310 group at Fermi National Accelerator Laboratory, of inclusive charged current neutrino and antineutrino interactions. The data sample consists of 21578 neutrino and 7358 antineutrino events within the fiducial regions of the calorimeter targets in the energy interval 20 2 >/E with increasing energy. R = (integral F2(x)dx/integral 2xF1(x)dx)-1 was determined in the energy interval 20 2 and xF3 for an isoscalar target are calculated and studied as functions of x at fixed energy and as functions of Q2 at fixed x. Both F2 and xF3 increase at small x and decrease at large x as either the energy of Q2 increases. The changes in the structure functions, hence the distributions in the scaling variables x and y, are attributed to charm production from strange quarks in the sea and the inherent Q2 dependence of the structure functions as predicted by quantum chromodynamics (QCD). Tables o by quantum chromodynamics (QCD). Tables of the structure functions are provided, in addition, momentum fraction distributions of the antiquarks are calculated by several methods and presented in various energy intervals. A comparison is made between the antiquark distributions and x anti s/sub p/(x) as derived from the antineutrino induced dimuon data from the experiment. Systematic effects are discussed throughout and detailed comparisons are made with data from other experiments

34

Pion and nucleon structure functions near x = 1

International Nuclear Information System (INIS)

In a colored-quark and vector-gluon model of hadrons we show that a quark carrying nearly all the momentum of a nucleon (xapprox. =1) must have the same helicity as the nucleon; consequently ?W2 /subn//?W2 p?3/7 as x?1, not 2/3 as might naively have been expected. Furthermore as x?1, ?W2/sup pi/approx. (1-x)2 and (sigma/subL//sigma/subT/)/sup pi/approx.?2Q-2(1-x)-2+O (g2); the resulting angular dependence for e+e-?h/sup plus-or-minus/+X is consistent with present data and has a distinctive form which can be easily tested when better data are available

35

Experimental moments of the nucleon structure function F2

Experimental data on the F2 structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n1 approaching 0, although the precision of the data did not allow to exclude the 1/5 value. The higher twist components of the proton and neutron moments suggest that multi-parton correlations are isospin independent.

Osipenko, M; Simula, S; Kulagin, S; Ricco, G

2007-01-01

36

Experimental moments of the nucleon structure function F2

Digital Repository Infrastructure Vision for European Research (DRIVER)

Experimental data on the F2 structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n<=12 moments. A comprehensive analysis of the moments in terms of the operator product expansion has been performed to separate the moments into leading and higher twist contributions. Particular attention was paid to the issue of nuclear corrections in the deuteron, when extracting the neutron moments from data. ...

Osipenko, M.; Melnitchouk, W.; Simula, S.; Kulagin, S.; Ricco, G.; Collaboration, Clas

2006-01-01

37

Nucleon structure functions from ??-Fe scattering at the Tevatron

Preliminary measurements of structure functions have been made from a sample of 1,281,000 ? ?and 270,000 ?? charged current events with 30 GeV < E ? < 600 GeV. These include a new value of the Gross-Llewellyn Smith Sum Rule, ?(1/x)(xF 3)dx=2.66 ± .03 (stat) ± .08 (syst), the ratio of cross sections, ?( ??)/?(? ?) = .511 ± .002 ( stat) ± .005 ( syst) , and an analysis of the Q 2 evolution of xF 3.

Smith, W. H.; Sandler, P. H.; Merritt, F. S.; Oreglia, M. J.; Schumm, B. A.; Arroyo, C.; Bachmann, K. T.; Blair, R. E.; Foudas, C.; King, B. J.; Lefmann, W. C.; Leung, W. C.; Mishra, S. R.; Oltman, E.; Quintas, P. Z.; Rabinowitz, S. A.; Sciulli, F. J.; Seligman, W. G.; Shaevitz, M. H.; Bernstein, R. H.; Borcherding, F. O.; Fisk, H. E.; Lamm, M. J.; Marsh, W.; Merritt, K. W.; Schellman, H.; Yovanovitch, D.; Bodek, A.; Budd, H. S.; de Barbaro, P.; Sakumoto, W. K.

1991-04-01

38

Polarized and unpolarized nucleon structure functions from lattice QCD

International Nuclear Information System (INIS)

We report on a high statistics quenched lattice QCD calculation of the deep-inelastic structure functions F1, F2, g1 and g2 of the proton and neutron. The theoretical basis for the calculation is the operator product expansion. We consider the moments of the leading twist operators up to spin four. Using Wilson fermions the calculation is done for three values of K, and we perform the extrapolation to the chiral limit. The renormalization constants, which lead us from lattice to continuum operators, are calculated in perturbation theory to one loop order. (orig.)

39

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

International Nuclear Information System (INIS)

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.)

40

Recent lattice QCD results on nucleon structure

Energy Technology Data Exchange (ETDEWEB)

I review recent developments in lattice calculations of nucleon structure. In particular, I cover the calculations of nucleon matrix elements related to generalized parton distribution functions, structure functions and form factors.

Konstantinos Orginos

2006-06-25

41

Recent lattice QCD results on nucleon structure

Energy Technology Data Exchange (ETDEWEB)

I review recent developments in lattice calculations of nucleon structure. In particular, I cover the calculations of nucleon matrix elements related to generalized parton distribution functions, structure functions and form factors.

Konstantinos Orginos

2006-07-01

42

Experimental moments of the nucleon structure function F2

Energy Technology Data Exchange (ETDEWEB)

Experimental data on the F2 structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n<=12 moments. A comprehensive analysis of the moments in terms of the operator product expansion has been performed to separate the moments into leading and higher twist contributions. Particular attention was paid to the issue of nuclear corrections in the deuteron, when extracting the neutron moments from data. The difference between the proton and neutron moments was compared directly with lattice QCD simulations. Combining leading twist moments of the neutron and proton we found the d/u ratio at x->1 approaching 0, although the precision of the data did not allow to exclude the 1/5 value. The higher twist components of the proton and neutron moments suggest that multi-parton correlations are isospin independent.

Mikhail Osipenko; W. Melnitchouk; Silvano Simula; Sergey Kulagin; Giovanni Ricco

2007-12-01

43

Experimental moments of the nucleon structure function F2

International Nuclear Information System (INIS)

Experimental data on the F2 structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n?12 moments. A comprehensive analysis of the moments in terms of the operator product expansion has been performed to separate the moments into leading and higher twist contributions. Particular attention was paid to the issue of nuclear corrections in the deuteron, when extracting the neutron moments from data. The difference between the proton and neutron moments was compared directly with lattice QCD simulations. Combining leading twist moments of the neutron and proton we found the d/u ratio at x?1 approaching 0, although the precision of the data did not allow to exclude the 1/5 value. The higher twist components of the proton and neutron moments suggest that multi-parton correlations are isospin independent

44

Effects of the quantity ?TS on the spin structure functions of nucleons in the resonance region

International Nuclear Information System (INIS)

In this paper, we investigate the effects of the quantity ?TS on the spin structure functions of nucleons in the resonance region. The Schwinger sum rule for the spin structure function g2(x,Q2) at the real photon limit is derived for the nucleon treated as a composite system, and it provides a crucial constraint on the longitudinal transition operator which has not been treated consistently in the literature. The longitudinal amplitude S1/2 is evaluated in the quark model with the transition operator that generates the Schwinger sum rule. The numerical results of the quantity ?TS are presented for both spin structure functions g1(x,Q2) and g2(x,Q2) in the resonance region. Our results show that this quantity plays an important role in the low Q2 region, which can be tested in future experiments at CEBAF. copyright 1996 The American Physical Society

45

Nucleon structure functions from ?mu-Fe scattering at the Tevatron

International Nuclear Information System (INIS)

We present preliminary results for nucleon structure functions measured in high energy neutrino interactions. Included are new results for the Gross-Llewellyn Smith Sum Rule, ?x/1xF3dx = 2.66 ± .03(stat)±.08(syst), the ratio of cross-sections, ?bar?/?? = .511 ± .002(stat) ± .005(syst), and an analysis of the Q2 evolution of xF3. 16 refs., 5 figs

46

Spin structure functions of the nucleon at low Q2 and ?

International Nuclear Information System (INIS)

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

47

International Nuclear Information System (INIS)

Generalized parton distributions provide information on the longitudinal and transverse distribution of partons in the fast moving nucleon. Furthermore, they contain information on the spin structure of the nucleon. First results of a lattice study of generalized parton distributions are presented. (orig.)

48

QCD analysis of the structure function F2 in muon nucleon scattering

International Nuclear Information System (INIS)

A QCD analysis in leading and next to leading order of the structure function F2 measured in deep inelastic muon nucleon scattering is presented. Taking into acount several phenomenological uncertainties, including the gluon description and the charm contribution, fits to the data give values of the QCD scale parameter ?sub(LO) in the range 70-250 MeV. A consistent description of muon scattering and lower Q2 electron scattering requires the presence of higher twist 1/Q2 contributions to the scale breaking which are then determined as a function of x from the data. (orig.)

49

On the relation between nuclear and nucleon Structure Functions and their moments

Digital Repository Infrastructure Vision for European Research (DRIVER)

Calculations of nuclear Structure Functions (SF) F_k^A(x,Q^2) routinely exploit a generalized convolution, involving the SF for nucleons F_k^N and the linking SF f^{PN,A} of a fictitious nucleus, composed of point-particles, with the latter usually expressed in terms of hadronic degrees of freedom. For finite Q^2 the approach seemed to be lacking a solid justification and the same is the case for recently proposed, effective nuclear parton distribution functions (pdf), which...

Rinat, A. S.; Taragin, M. F.

2005-01-01

50

A detailed study of the nucleon structure functions in deep inelastic muon scattering in iron

International Nuclear Information System (INIS)

The chi and Q2 dependences of the nucleon structure functions F2sup(N)(chi,Q2) and Rsup(N)(chi,Q2) have been measured in deep inelastic muon scattering from an iron target in the region 0.0422. By comparing data taken at different incident muon energies Rsup(N) was found to be small with an average value of 0.026+-0.037 (stat.)+-0.174 (syst.). The observed deviations from scaling gave the value of the QCD mass scale parameter theta. The fraction of the momentum of the nucleon carried by quarks was found to be (49+-1 stat.+-4 syst.)% at Q2proportional15 GeV2. (orig./HSI)

51

Nucleon size and nucleon structure

International Nuclear Information System (INIS)

Hidden-color basis states of multiquark systems are expressed in terms of states involving color-singlet hadrons. The size of various nucleon form factors is used to separate the interior perturbative region of quarks from the exterior nonperturbative region of hadrons. The distinction between the baryon interior and its exterior appears to be relevant in baryon spectroscopy and in nuclear forces. 26 refs.; 1 figure

52

Gold-plated moments of nucleon structure functions in baryon chiral perturbation theory

We obtain leading- and next-to-leading order predictions of chiral perturbation theory for several prominent moments of nucleon structure functions. These free-parameter free results turn out to be in overall agreement with the available empirical information on all of the considered moments, in the region of low-momentum transfer ($Q^2 < 0.3$ GeV$^2$). Especially surprising is the situation for the $\\delta_{LT}$ moment, which thus far was not reproducible for proton and neutron simultaneously in chiral perturbation theory. This problem, known as the "$\\delta_{LT}$ puzzle," is not seen in the present calculation.

Lensky, Vadim; Pascalutsa, Vladimir

2014-01-01

53

In this paper we present an analytic result for the evolution in $Q^2$ of the structure functions for the neutrino-nucleon interaction, valid at twist-2 in the region of small values of the Bjorken $x$ variable and for soft non-perturbative input. In the special case of flat initial conditions, we include in the calculation also the contribution of the twist-4 gluon recombination corrections, whose effect in the evolution is explicitly determined. Finally, we estimate the resulting charged-current neutrino-nucleon total cross section and discuss its behavior at ultra-high energies.

Fiore, R; Kotikov, A V; Paccanoni, F; Papa, A; Predazzi, Enrico

2004-01-01

54

Nuclear effects in F{sub 3} structure function of nucleon

Energy Technology Data Exchange (ETDEWEB)

We study nuclear effects in the F{sub 3}{sup A}(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{sup 2})=(F{sub 3}{sup A}(x,Q{sup 2}))/(AF{sub 3}{sup N}(x,Q{sup 2})) and the Gross-Llewellyn Smith (GLS) integral G(x,Q{sup 2})={integral}{sub x}{sup 1}dxF{sub 3}{sup A}(x,Q{sup 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 [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India)], E-mail: sajathar@rediffmail.com; Singh, S.K. [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Vacas, M.J. Vicente [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, 46100 Burjassot (Valencia) (Spain)

2008-10-02

55

A detailed study of nucleon structure function in nuclei in the valence quark region

Energy Technology Data Exchange (ETDEWEB)

The so called {open_quotes}EMC effect{close_quotes} discovered during the 1980`s, has caused a big controversy in the community of nuclear and high energy physicists; during the last ten years, five experiments have been performed in different laboratories and several hundreds of papers about the possible interpretation of the modification of the nucleon structure function inside nuclei have been published. However, from the experimental point of view, the main goal of four experiments (EMC, BCDMS, NMC, FNAL) has been to emphasize the region of low x{sub b}, where shadowing effects appear. In the region of valence quarks and nuclear effects (x{sub b} > 0.1 - 0.2) the most reliable data presently available are from the SLAC E139 experiment performed in 1983 with only 80 hours of beam time. New precise data in the valence quark region are necessary to measure separate structure functions F{sub 2}(x{sub b}, Q{sup 2}) and R{sup lt}(x{sub b},Q{sup 2}) = {sigma}{sub l}/{sigma}{sub t}, and to investigate the real A-dependence of the ratio between bound and free-nucleon structure functions which is not completely defined by the SLAC data. Moreover, from the nuclear physics point of view, a measurement on some unexplored nuclei, like {sup 3}He and {sup 48}Ca, would be of great interest. The intermediate scaling region (0.1 < x{sub b} < 0.7) would be accessible at CEBAF if the machine energy will reach 6-8 GeV, as suggested by all the tests performed on the RF cavities. This physics program has been already presented in two letter of intents.

Bianchi, N. [INFN-Laboratori, Nazionali di Frascati (Italy)

1994-04-01

56

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we present an analytic result for the evolution in $Q^2$ of the structure functions for the neutrino-nucleon interaction, valid at twist-2 in the region of small values of the Bjorken $x$ variable and for soft non-perturbative input. In the special case of flat initial conditions, we include in the calculation also the contribution of the twist-4 gluon recombination corrections, whose effect in the evolution is explicitly determined. Finally, we estimate the re...

Predazzi, Enrico

2004-01-01

57

Bloom-Gilman duality of inelastic structure functions in nucleon and nuclei

International Nuclear Information System (INIS)

The Bloom-Gilman local duality of the inelastic structure function of the proton, the deuteron, and light complex nuclei is investigated using available experimental data in the squared four-momentum transfer range from 0.3 to 5 (GeV/c)2. The results of our analysis suggest that the onset of the Bloom-Gilman local duality is anticipated in complex nuclei with respect to the case of the proton and the deuteron. A possible interpretation of this result in terms of a rescaling effect is discussed with particular emphasis on the possibility of reproducing the damping of the nucleon-resonance transitions observed in recent electroproduction data off nuclei. copyright 1998 The American Physical Society

58

Tests of perturbative QCD using CCFR data for measurements of nucleon structure functions

We present measurements of nucleon structure functions, F2( ?, Q2) and xFs( ?, Q2), from the high-statistics, high-energy neutrino-iron scattering experiment at the Fermilab Tevatron. The existing high-statistics xF 3 determination by the CDHSW collaboration is compared to our data. The data presented here constitute the first corroboration of the QCD prediction of xF 3 evolution at low-?, and yields ? overlineMS=210±28±41 MeV, and a determination of the GLS sum rule at Q 2 = 3 GeV 2, S GLS = limit??1{xF s}/{?}=2.50±0.018 (stat.)±0.078 (syst.) . Our value of ? overlineMS yields ?3( Mz) = .111 ± .002 ± .003 ± .003 (scale). Comparison of the neutrino determination of F2( ?, Q2) with that obtained from the charged-lepton ( e or ?) scattering leads to a precise test of the mean-square charge prediction by the Quark Parton Model. The SLAC-CCFR and BCDMS structure function provide a consistent and precise set of structure functions over a large range of Q2.

Bodek, A.; Budd, H. S.; de Barbaro, P.; Sakumoto, W. K.; Leung, W. C.; Quintas, P. Z.; Sciulli, F.; Arroyo, C.; Bachmann, K. T.; Blair, R. E.; Foudas, C.; King, B. J.; Lefmann, W. C.; Mishra, S. R.; Oltman, E.; Rabinowitz, S. A.; Seligman, W. G.; Shaevitz, M. H.; Merritt, F. S.; Oreglia, M. J.; Schumm, B. A.; Bernstein, R. H.; Borcherding, F.; Fisk, H. E.; Lamm, M. J.; Marsh, W.; Merritt, K. W. B.; Schellman, H.; Yovanovitch, D. D.; Sandler, P. H.; Smith, W. H.

1993-04-01

59

Axial structure of the nucleon

We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.

Bernard, V; Meißner, Ulf G; Elouadrhiri, Latifa; Mei{\\ss}ner, Ulf-G.

2002-01-01

60

Axial structure of the nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.

Bernard, Ve?ronique; Elouadrhiri, Latifa; Meißner, Ulf-g

2001-01-01

61

Axial structure of the nucleon

Energy Technology Data Exchange (ETDEWEB)

We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton. (author)

Bernard, Veronique [Universite Louis Pasteur de Strasbourg, Groupe de Physique Theorique, Strasbourg (France)]. E-mail: bernard@lpt6.u-strasbg.fr; Elouadrhiri, Latifa [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)]. E-mail: latifa@jlab.org; Meissner, Ulf-G. [Forschungszentrum Juelich, Institut fuer Kernphysik (Theorie), Juelich (Germany)]. E-mail: u.meissner@fz-juelich.de

2002-01-01

62

Axial structure of the nucleon

International Nuclear Information System (INIS)

We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton. (author)

63

Axial structure of the nucleon

International Nuclear Information System (INIS)

We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton

64

We present analyses on nucleon structure functions at small Bjorken x in the framework of holographic QCD. In this study, we improve the description of the target nucleon in the current setup of the holographic model by introducing a soft-wall AdS/QCD model, in which the anti-de Sitter geometry is smoothly cut off at the infrared boundary. Combining the improved Pomeron-nucleon coupling and the wave function of the five-dimensional U(1) vector field with the Brower-Polchinski-Strassler-Tan Pomeron exchange kernel, we obtain the structure functions. Here we focus on the nonperturbative kinematical region, where 10-6?x?10-2 and Q2? a few (GeV2), and show that our calculations for F2p and FLp are consistent with experimental data of the deep inelastic scattering at HERA. Furthermore, we find that the resulting longitudinal-to-transverse ratio of the structure functions, FLp/FTp, depends on both x and Q2.

Watanabe, Akira; Suzuki, Katsuhiko

2014-06-01

65

Digital Repository Infrastructure Vision for European Research (DRIVER)

I investigate the behavior of spin-dependent parton distribution functions in the regions of small and large momentum fractions $x$. I present a systematic comparison between predictions for relevant observables obtained with various models of nucleon spin structure and a recent global analysis of spin-dependent distributions, NNPDFpol1.1. Together with its unpolarized counterpart, NNPDF2.3, they form a mutually consistent set of parton distributions. Because they include mo...

Nocera, Emanuele Roberto

2014-01-01

66

International Nuclear Information System (INIS)

There is a need for covariant solutions of bound state equations in order to construct realistic QCD based models of mesons and baryons. Furthermore, we ideally need to know the structure of these bound states in all kinematical regimes, which makes a direct solution in Minkowski space (without any 3-dimensional reductions) desirable. The Bethe-Salpeter equation (BSE) for bound states in scalar theories is reformulated and solved for arbitrary scattering kernels in terms of a generalized spectral representation directly in Minkowski space. This differs from the conventional Euclidean approach, where the BSE can only be solved in ladder approximation after a Wick rotation. An application of covariant Bethe-Salpeter solutions to a quark-diquark model of the nucleon is also briefly discussed. (orig.)

67

International Nuclear Information System (INIS)

The structure function S(q,?) for quasielastic electron scattering on a nonrelativistic two-nucleon model system is evaluated numerically. These S values are considered as pseudodata to study sum rules, y scaling, and the cumulant expansion. For the force models considered it is found that the reduced structure function (q/2m)S(q,?) in the limit q?? scales to the longitudinal momentum distribution PL(y) in the target. Except for small y values, this limit, however, is reached only very slowly, which may be due to the strictly nonrelativistic treatment. The cumulant expansion based on low-order cumulants is not useful. We also derive the analytical result that in our potential model S(q,?)=O(?-5.5) for ??? and fixed q. This shows that higher-order cumulants do not exist

68

International Nuclear Information System (INIS)

We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 2 2. The data have been used to accurately perform over 170 Rosenbluth-type longitudinal/transverse separations. The precision R ?L/?T data are presented here, along with the first separate values of the inelastic structure functions F1 and FL in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q2 = 1 GeV2 in the separated structure functions independently

69

Measurement of the nucleon g sub 2 spin structure function at SLAC

The deep inelastic polarized structure functions g sup p sup , sup n sub 2 and g sup p sup , sup n sub 1 have been recently measured at the Stanford Linear Accelerator Center (SLAC) End Station A facility by the E155 Collaboration using 48.4 GeV and 38.8 GeV longitudinally polarized electrons incident on longitudinally and transversely polarized ammonia (NH sub 3) and lithium deuteride ( sup 6 Li sup 2 H sub 3) targets. The proton and deuteron data are combined to extract the neutron structure functions.

Rondon, Oscar A

1999-01-01

70

Nucleon structure from stochastic estimators

Energy Technology Data Exchange (ETDEWEB)

The structure of the proton and neutron, parameterized by moments of generalized parton distribution functions (GPDs), can be accessed from first principle through the computation of baryon three-point functions with lattice QCD. The numerical effort involved in such computations is sizable and thus an efficient algorithm that extracts most information at given cost is highly desirable. In this work we demonstrate that stochastic estimation techniques can substantially increase the information/cost ratio. We examine the available results at N{sub f}=2 for the nucleon axial coupling gA and iso-vector quark momentum fraction

Najjar, Johannes Siegfried Samir

2014-10-01

71

We re-examine the estimates of the higher twist contributions to the integral of $g_1$, the polarised structure function of the nucleon, based on QCD sum rules. By including corrections both to the perturbative contribution and to the low energy contribution we find that the matrix elements of the relevant operators are more stable to variations of the Borel parameter $M^2$, allowing for a meaningful estimate of the matrix elements. We find that these matrix elements are typically twice as large as previous estimates. However, inserting these new estimates into the recently corrected expressions for the first moments of $g_1$ leads to corrections too small to affect the phenomenological analysis. For the unpolarised case the higher twist corrections to the GLS and Bjorken sum rules are substantial and bring the estimate of $\\Lambda_{QCD}$ from the former into good agreement with that obtained from the $Q^2$ dependence of deep inelastic data.

Ross, Graham G; Ross, Graham G.

1994-01-01

72

Nucleon Transverse Structure at COMPASS

COMPASS is a fixed target experiment at CERN. Part of its physics programme is dedicated to study the transverse spin and the transverse momentum structure of the nucleon using SIDIS. For these measurements, data have been collected using transversely polarised proton and deuteron targets. A selection of recent measurements of azimuthal asymmetries using data collected with transversely polarised protons is presented.

Makke, Nour

2014-01-01

73

International Nuclear Information System (INIS)

570 000 neutrino-iron and 370 000 antineutrino-iron charged-current events were obtained from the Wide Band Beam exposure of the CDHS detector at CERN in 1983, at energies ranging from 20 to 400 GeV. These large statistics allowed a precise measurement of the charged-current differential cross-sections and a detailed study of systematic effects. The nucleon structure functions have been determined in the framework of the quark-parton model, in the kinematic range: 0.01522/c2. The longitudinal structure function FL(x) is in good agreement with the QCD predicted shape. Deviations from scale invariance are clearly seen from the functions F2 and xF3. The Q2 evolution of the valence quark distribution has been compared with the QCD prediction in order to measure the scale parameter ?. A good agreement is obtained only if the low Q2 points are removed from the comparison. Our experiment favours a value of ? between 50 and 250 MeV

74

International Nuclear Information System (INIS)

The spin and flavor structure of quarks and gluons in nucleons and nuclei is more complicated than expected in the original naive quark model. Recent results which show some of the key failures of the naive picture are summarized here with emphasis on recent results from the HERMES experiment. Some future options to study the quarks structure in exclusive processes in electroproduction, photoproduction and pp annihilation are presented. (orig.)

75

Energy Technology Data Exchange (ETDEWEB)

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{approx}2.4 GeV with four-momentum transfers Q{sup 2} ranging from 0.2 to 5(GeV/c){sup 2}. These data, together with previous measurements of the inclusive electron scattering off proton and deuteron, which cover a similar continuous two-dimensional region of Q{sup 2} 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 F{sub 2} structure function and its moments. Using an OPE-based twist expansion, we studied the Q{sup 2}-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 F{sub 2} 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 uncertainties, to be smaller with respect to the deuteron case for n<7, suggesting partial parton deconfinement in nuclear matter. We speculate that the spatial extension of the nucleon is changed when it is immersed in the nuclear medium.

Osipenko, M., E-mail: osipenko@ge.infn.i [INFN, Sezione di Genova, 16146 Genova (Italy); Skobeltsyn Nuclear Physics Institute, Skobeltsyn Nuclear Physics Institute, 119899 Moscow (Russian Federation); Ricco, G. [INFN, Sezione di Genova, 16146 Genova (Italy); Simula, S. [INFN, Sezione di ROMA III, 00146 Rome (Italy); Ripani, M.; Taiuti, M. [INFN, Sezione di Genova, 16146 Genova (Italy); Adhikari, K.P.; Amaryan, M.J. [Old Dominion University, Norfolk, VA 23529 (United States); Anghinolfi, M. [INFN, Sezione di Genova, 16146 Genova (Italy); Avakian, H. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); INFN, Laboratori Nazionali di Frascati, 00044 Frascati (Italy); Baghdasaryan, H. [University of Virginia, Charlottesville, VA 22901 (United States); Battaglieri, M. [INFN, Sezione di Genova, 16146 Genova (Italy); Batourine, V. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Bedlinskiy, I. [Institute of Theoretical and Experimental Physics, Moscow 117259 (Russian Federation); Biselli, A.S. [Fairfield University, Fairfield, CT 06824 (United States); Rensselaer Polytechnic Institute, Troy, NY 12180-3590 (United States); Branford, D. [Edinburgh University, Edinburgh EH9 3JZ (United Kingdom); Briscoe, W.J. [The George Washington University, Washington, DC 20052 (United States); Brooks, W.K. [Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Burkert, V.D. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Careccia, S.L. [Old Dominion University, Norfolk, VA 23529 (United States); Carman, D.S. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

2010-11-15

76

New relations in lepton-nucleon scattering independent of the nucleon structure

International Nuclear Information System (INIS)

New relations in deep inelastic and (quasi-)elastic scattering of polarized electrons and positrons (?±-mesons) on non-polarized nucleons have been obtained. They connect cross sections with standard model parameters and are independent of the structure functions and form factors of the nucleon. A well known example is the Paschos-Wolfenstein relation in (?-bar)N-scattering. 6 refs

77

Bloom-Gilman duality of inelastic structure functions in nucleon and nuclei

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Bloom-Gilman local duality of the inelastic structure function of the proton, the deuteron and light complex nuclei is investigated using available experimental data in the squared four-momentum transfer range from 0.3 to 5 (GeV/c)**2. The results of our analysis suggest that the onset of the Bloom-Gilman local duality is anticipated in complex nuclei with respect to the case of the protonand the deuteron. A possible interpretation of this result in terms of a rescaling ...

Ricco, G.; Anghinolfi, M.; Ripani, M.; Simula, S.; Taiuti, M.

2014-01-01

78

International Nuclear Information System (INIS)

We have studied the nuclear effects on high energy antineutrino charged current interactions by comparing the data which were taken in the Bubble Chamber BEBC filled with Neon and Deuterium. On the one hand, the study of nuclear reinteractions gave us the possibility to estimate the formation time of hadrons. On the other hand, the comparison of structure functions does not show any significant difference between Neon and Deuterium. Though this result does not contradict the effects observed with charged leptons by the EMC and SLAC experiments, it is strongly incompatible with certain theoretical interpretations which implied a stronger effect in antineutrino interactions

79

Finite-temperature quantum field theory and structure functions of the nucleon

International Nuclear Information System (INIS)

The deep inelastic scattering of leptons off a proton in the statistical model is considered. The interior of the nucleon is viewed as a thermalized assembly of up and down quarks and gluons. This enables the incorporation of features which are absent in the parton model. These include the presence of identical quarks and gluons in initial and final states and of quantum statistical correlations which have a role to play in the propagation of particles when considering Feynman diagrams containing internal lines in next-to-leading-order calculations. These features are incorporated through the use of Fermi-Dirac and Bose-Einstein distributions for quarks and gluons, respectively. Stimulated emission factors for final-state gluons and Pauli-blocking factors for final-state quarks are incorporated. The propagation of particles through a many-body medium is taken into account by using thermal Feynman rules for propagators and vertices. The statistical model could also be seen as an attempt to describe the interior of the nucleon at a more fundamental level than that attained through the use of arbitrary parton distributions containing many parameters in the parton model. 79 refs., 46 figs., 8 tabs

80

Nucleon spin structure at very high x

Energy Technology Data Exchange (ETDEWEB)

Dyson–Schwinger equation treatments of the strong interaction show that the presence and importance of nonpointlike diquark correlations within the nucleon are a natural consequence of dynamical chiral symmetry breaking. Using this foundation, we deduce a collection of simple formulae, expressed in terms of diquark appearance and mixing probabilities, from which one may compute ratios of longitudinal-spin-dependent u- and d-quark parton distribution functions on the domain x?1. A comparison with predictions from other approaches plus a consideration of extant and planned experiments shows that the measurement of nucleon longitudinal spin asymmetries on x?1 can add considerably to our capacity for discriminating between contemporary pictures of nucleon structure.

Roberts, Craig D.; Holt, Roy J. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Schmidt, Sebastian M. [Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich (Germany)

2013-11-25

81

Experimental moments of the nucleon structure function F{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Experimental data on the F{sub 2} structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n{<=}12 moments. A comprehensive analysis of the moments in terms of the operator product expansion has been performed to separate the moments into leading and higher twist contributions. Particular attention was paid to the issue of nuclear corrections in the deuteron, when extracting the neutron moments from data. The difference between the proton and neutron moments was compared directly with lattice QCD simulations. Combining leading twist moments of the neutron and proton we found the d/u ratio at x{yields}1 approaching 0, although the precision of the data did not allow to exclude the 1/5 value. The higher twist components of the proton and neutron moments suggest that multi-parton correlations are isospin independent.

Osipenko, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Genova, Genoa, 16146 (Italy); Melnitchouk, W. [Jefferson Lab, Newport News, Virginia 23606 (United States); Simula, S. [Istituto Nazionale di Fisica Nucleare, Sezione Roma III, Roma 00146 (Italy); Kulagin, S. [Institute for Nuclear Research of Russian Academy of Science, Moscow 117312 (Russian Federation); Ricco, G. [Universita di Genova, Genoa 16146 (Italy)

2007-12-15

82

Nucleon structure from stochastic estimators

Using stochastic estimators for connected meson and baryon three-point functions has successfully been tried in the past years. Compared to the standard sequential source method we trade the freedom to compute the current-to-sink propagator independently of the hadron sink for additional stochastic noise in our observables. In the case of the nucleon we can use this freedom to compute many different sink-momentum/polarization combinations, which grants access to more virtualities. We will present preliminary results on the scalar, electro-magnetic and axial form factors of the nucleon in $N_f=2+1$ lattice QCD and contrast the performance of the stochastic method to the sequential source method. We find the stochastic method to be competitive in terms of errors at fixed cost.

Bali, Gunnar S; Gläßle, Benjamin; Göckeler, Meinulf; Najjar, Johannes; Rödl, Rudolf; Schäfer, Andreas; Sternbeck, André; Söldner, Wolfgang

2013-01-01

83

Calculation of structure functions of the nucleon in the framework of QCD on the lattice

International Nuclear Information System (INIS)

In order to compute moments of hadronic structure functions one needs matrix elements of composite operators appearing in the operator product expansion of appropriate currents. For deep inelastic electron proton scattering it is shown in detail how the matrix elements and moments (flavour Non-Singlet case) are calculated in lattice QCD using Wilson fermions in the quenched approximation. One step in such a calculation is the renormalisation of the operators to obtain finite answers in the continuum limit. In this work a non-perturbative renormalisation of operators that are bilinear in the quark fields is investigated on the lattice. Several improvements of the method that was first introduced by Martinelli et al. are presented. Z factors up to a scale of 80 GeV2 are computed and discussed, taking special regard of lattice cut-off effects. To yield the desired moments the renormalized matrix elements have to be multiplied by the corresponding Wilson coefficients. Since the Wilson coefficients are usually computed in the MS scheme, the Z factors (renormalized operators) are converted to this continuum scheme. The calculation of the conversion factors is presented in detail. The converted renormalisation factors are compared with lattice perturbation theory and the so-called tadpole improved perturbation theory, that was proposed by Lepage and Mackenzie to remedy the poor convergence properties of lattice perturbation theory. Computing the renormalisation con theory. Computing the renormalisation constants for a large range of scales ?2 it can be found out at which scales (if at all) perturbative behaviour sets in

84

The quark structure of the nucleons

International Nuclear Information System (INIS)

The suitableness of the non-relativistic potential model for the description of quarks in nucleons is proved and the model extensively presented. Practical applications are some contributions to the nucleon-nucleon interaction which result from the quark structure of the nucleons. These are especially the quark-gluon exchange and the quark-pion exchange between nucleons. The influences of these interactions on the s and p scattering of the nucleons are calculated in the framework of the resonating-group method. Furthermore we study the change of the quark structure if two nucleons approach very closely. The interaction of the nucleons by quark-gluon exchange causes an increase of the nucleon radius and a shift of the quark momenta to lower values. On this base the momentum distribution of quarks in nuclei is calculated and a natural explanation of the EMC effect is given. The distance distribution of nucleons and their Fermi motion are calculated for this in the shell model. Then we make further considerations in connection with the flavor symmetry, the collapse of the nucleons and the properties of six-quark bags. Altogether it is shown that in the potential model the most different effects of the quark structure of nucleons can be surprisingly well described in an illustrative way. (orig.)

85

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

86

Nucleon form factors and structure functions with N_f=2+1 dynamical domain wall fermions

We report isovector form factors and low moments of structure functions of nucleon in numerical lattice quantum chromodynamics (QCD) from the on-going calculations by the RIKEN-BNL-Columbia (RBC) and UKQCD Collaborations with (2+1) dynamical flavors of domain-wall fermion (DWF) quarks. We calculate the matrix elements with four light quark masses, corresponding to pion mass values of m_\\pi = 330-670 MeV, while the dynamical strange mass is fixed at a value close to physical, on (2.7 fm)^3 spatial volume. We found that our axial charge, g_A, at the lightest mass exhibits a large deviation from the heavier mass results. This deviation seems to be a finite-size effect as the g_A value scales with a single parameter, m_\\pi L, the product of pion mass and linear spatial lattice size. The scaling is also seen in earlier 2-flavor dynamical DWF and Wilson quark calculations. Without this lightest point, the three heavier mass results show only very mild mass dependence and linearly extrapolate to g_A=1.16(6). We dete...

Yamazaki, T

2007-01-01

87

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

88

Space-time structure of a bound nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

Distortions of bound nucleon space-time structure, measured in deep inelastic scattering off nuclei, are discussed from view-point of a theoretical approach based on the Bethe-Salpeter formalism. It is shown that modification of the structure function $F_2^{\\rm N}$ results from relative time dependence in Green functions of bound nucleons. The modification plays fundamental role in analysis of deep inelastic scattering experiments and allows one to obtain new information abo...

Molochkov, A. V.

2000-01-01

89

Spin structure of the nucleon and triangle anomaly

International Nuclear Information System (INIS)

It is shown that the gluon contribution to the sum rule for spin parton distribution functions which determines the spin of the nucleon is fixed by the axial Adler-Bell-Jackiw anomaly. The new sum rule is consistent with OCD evolution equations and predicts that quarks carry about 70% of the nucleon spin. The gluon contribution results in negative extra term to the Ellis-Jaffe sum rule for the structure function g1 which accounts for its disagreement with experiment

90

International Nuclear Information System (INIS)

In this thesis the nucleon structure function xF3 is determined from the inclusive measurement of the deep inelastic neutrino nucleon charged current interaction. The data were taken in the CERN wide band neutrino beam using the detector of the CERN-Dortmund-Heidelberg-Saclay collaboration. This detector serves at the same time as target, as hadron energy calorimeter and as muon spectrometer. One major aspect of this work was to study the possibility of using high statistics wide band beam data for structure function analysis. The systematic errors specific to this kind of beam are investigated. To obtain the differential cross sections about 100000 neutrino and 75000 antineutrino events in the energy range 20-200 GeV are analysed. The differential cross sections are normalized to the total cross sections, as measured in the narrow band beam by the same collaboration. The calculated structure function xF3 shows significant deviations from scaling. These scaling violations are compared quantitatively with the predictions of quantum chromodynamics. (orig.)

91

Short-range correlations of partons & 3D nucleon structure

Directory of Open Access Journals (Sweden)

Full Text Available Dynamical breaking of chiral symmetry in QCD is caused by non-perturbative interactions on a scale ? ? 0.3 fm much smaller than the hadronic size R ? 1 fm. This has important consequences for the nucleon structure such as the prediction that the transverse momentum distribution of sea quarks is significantly broader than the pT -distribution of valence quarks due to short-range correlations between sea quarks in the nucleon’s light-cone wave function.

Schweitzer P.

2014-03-01

92

International Nuclear Information System (INIS)

Various aspects of nuclear physics at intermediate energies, in connection with the description of the nucleon-nucleon potential in terms of mesons, are presented in this thesis. The meson exchange current contribution is studied in the case of the deuteron (np capture and electrodisintegration near threshold). A consistent description of these processes is discussed, with particular emphasis on the effective range of the current, for momentum transfers as large as q2?1 (GeV/c)2. The structure of finite nuclei and nuclear matter is then analysed in the framework of a relativistic formalism, in which the negative energy component of the nucleon wave function is explicitly taken into account. The nuclear matter saturation mechanism is studied in details and compared with the non-relativistic limit. Properties of finite nuclei are also discussed. Finally, the structure of the nucleon itself in the nuclear medium is investigated. A connection between the polarisation of the nucleon (three valence quark component), the incompressibility parameter and the mass of the first monopole excitation of the nucleon is presented

93

The spin structure of the nucleon

International Nuclear Information System (INIS)

The present understanding of the spin structure of the nucleon is described. The world's data on spin-dependent deep inelastic scattering is summarized with particular emphasis on the new data from the last year. Next-to-leading order (NLO) QCD analysis of existing data provides another successful test of QCD. However, the uncertainty arising from the low x extrapolation provides a serious impediment to extracting information on the spin structure of the nucleon using sum rules formed from inclusive data. The NLO analyses suggest that the gluon contribution to the nucleon spin is sizable. Possible initiatives to directly probe the gluon spin are described. Semi-inclusive measurements at present underway will study new aspects of the nucleon spin structure

94

Energy Technology Data Exchange (ETDEWEB)

We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q{sup 2} < 5.5 GeV{sup 2}. The data have been used to accurately perform over 170 Rosenbluth-type longitudinal/transverse separations. The precision R = {sigma}{sub L}/{sigma}{sub T} data are presented here, along with the first separate values of the inelastic structure functions F{sub 1} and F{sub L} in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q{sup 2} = 1 GeV{sup 2} in the separated structure functions independently.

Yongguang Liang; Michael Christy; Abdellah Ahmidouch; Christopher Armstrong; John Arrington; Arshak Asaturyan; Steven Avery; O. Baker; Douglas Beck; Henk Blok; C.W. Bochna; Werner Boeglin; Peter Bosted; Maurice Bouwhuis; Herbert Breuer; Daniel Brown; Antje Bruell; Roger Carlini; Jinseok Cha; Nicholas Chant; Anthony Cochran; Leon Cole; Samuel Danagoulian; Donal Day; James Dunne; Dipangkar Dutta; Rolf Ent; Howard Fenker; B. Fox; Liping Gan; Haiyan Gao; Kenneth Garrow; David Gaskell; Ashot Gasparian; Don Geesaman; Ronald Gilman; Paul Gueye; Mark Harvey; Roy Holt; Xiaodong Jiang; Mark Jones; Cynthia Keppel; Edward Kinney; Wolfgang Lorenzon; Allison Lung; David Mack; Pete Markowitz; J.W. Martin; Kevin McIlhany; Daniella Mckee; David Meekins; M.A. Miller; Richard Milner; Joseph Mitchell; Hamlet Mkrtchyan; Robert Mueller; Alan Nathan; Gabriel Niculescu; Maria-Ioana Niculescu; Thomas O' neill; Vassilios Papavassiliou; Stephen Pate; Rodney Piercey; David Potterveld; Ronald Ransome; Joerg Reinhold; E. Rollinde; Oscar Rondon-Aramayo; Philip Roos; Adam Sarty; Reyad Sawafta; Elaine Schulte; Edwin Segbefia; C. Smith; Samuel Stepanyan; Steffen Strauch; Vardan Tadevosyan; Liguang Tang; Raphael Tieulent; Vladas Tvaskis; Alicia Uzzle; William Vulcan; Stephen Wood; Feng Xiong; Lulin Yuan; Markus Zeier; Benedikt Zihlmann; Vitaliy Ziskin

2004-10-01

95

Energy Technology Data Exchange (ETDEWEB)

Higher twist effects in the deeply inelastic scattering are studied. We start with a short review of the theoretical results on higher twists in QCD. Within the saturation model we perform a twist analysis of the nucleon structure functions F{sub T} and F{sub L} at small value of the Bjorken variable x. The parameters of the model are fitted to the HERA F{sub 2} data, and we derive a prediction for the longitudinal structure function F{sub L}. We conclude that for F{sub L} the higher twist corrections are sizable whereas for F{sub 2}=F{sub T}+F{sub L} there is a nearly complete cancellation of twist-4 corrections in F{sub T} and F{sub L}. We discuss a few consequences for future LHC measurements. (orig.)

Bartels, Jochen [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Golec-Biernat, Krzysztof [Rzeszow Univ. (Poland). Inst. of Physics; Polish Academy of Sciences, Krakow (Poland). Inst. of Nuclear Physics; Motkyka, Leszek [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Uniwersytet Jagiellonski, Krakow (Poland). Inst. Fizyki

2009-11-15

96

On the resonance structure in nucleon-nucleon scattering

International Nuclear Information System (INIS)

A possible explanation of resonance-like structure in 1D2 and 3F3 proton-proton phase parameters at medium energy is suggested by the analysis of an exactly soluble coupled channel model. Looping in the Argand plot is mainly due to the nucleon-delta branch cut. This effect is already present in the N? box diagram, but is modified by higher order multiple scattering. Poles occur close to the N? branch point and originate from left-hand singularities in the unphysical sheet. (orig.)

97

We summarize recent developments in the understanding of nucleon structure. New data on F2, R and F2c, over a wide range of Q2 and x, are described. Conventional leading twist NLO perturbative QCD gives an excellent account 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.

Ball, R D

1996-01-01

98

Chiral symmetry and nucleon structure

International Nuclear Information System (INIS)

Recently it has been realized that significant tests of the validity of QCD are available in low energy experiments (E < 500 MeV) by exploiting the property of (broken) chiral symmetry. This technique has been highly developed in The Goldstone boson sector by the work of Gasser and Leutwyler. Application to the nucleon system is much more difficult and is now being carefully developed

99

International Nuclear Information System (INIS)

Within the chiral bag model (CBM) the spin-dependent structure functions of a polarized proton g1p(x) and polarized neutron g1n(x) are investigated. The results obtained within CBM with a scalar ?qq coupling agree with EMC experimental data rather well. 11 refs.; 1 fig.; 2 tabs

100

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

101

International Nuclear Information System (INIS)

Deep inelastic scattering cross sections have been measured with the CERN SPS muon beam at incident energies of 120 and 200 Gev. Approximately 100000 events at each energy are used to obtain the structure function F2(x, Q2) in the kinetic region 0.3222. It is seen from these data that Q2 dependence of the structure function is very slight for Q2>25 GeV2. A more detailed description of F2(x, Q2) can be obtained in the framework of the QCD. On the basis of the obtained data the ? parameter characterizing the strength of strong interactions has been determined by different methods and occurred to be about 100 MeV. This value is lower than what has been found elsewhere

102

Deep inelastic scattering cross sections have been measured with the CERN SPS muon beam at incident energies of 120 and 200 GeV. Approximately 10000 events at each energy used to obtain the structure function F/sub 2/(x, Q/sup 2/) in the kinematic region 0.3

Bollini, D; Benvenuti, Alberto C; Bozzo, M; Brun, R; Cvach, J; Dobrowolski, T; Fadeev, N G; Feltesse, J; Frabetti, P L; Gennow, H; Golutvin, I A; Goossens, M; Heiman, G; Jamnik, D; Kiryushin, Yu T; Kisselev, V S; Klein, M; Kopp, R; Krivokhizhin, V G; Kukhtin, V V; Maillard, J; Malasoma, J M; Meyer-Berkhout, U; Milsztajn, A; Monari, L; Navach, F; Navarria, Francesco Luigi; Nowak, Wolf-Dieter; Piemontese, L; Pilcher, J E; Renardy, J F; Sacquin, Yu; Savin, I A; Schinzel, D; Smadja, G; Smirnov, G I; Staude, A; Teichert, K M; Tirler, R; Verrecchia, P; Vesztergombi, G; Virchaux, M; Volodko, A G; Voss, R; Zácek, J; Zupancic, Crtomir

1981-01-01

103

New Results on Nucleon Spin Structure

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, $A_1^n$, in the high-$x$ region are discussed. The new data shows that $A_1^n$ becomes positive at high $x$. They provide crucial input for the global ...

Chen, Jian-ping

2005-01-01

104

Structure and Spin of the Nucleon

Energy Technology Data Exchange (ETDEWEB)

Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.

Avakian, Harut A. [JLAB

2014-03-01

105

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

106

Exploring the transverse spin structure of the nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discuss our present understanding of the transverse spin structure of the nucleon and of related properties originating from parton transverse motion. Starting from the transversity distribution and the ways to access it, we then address the role played by spin and transverse momentum dependent (TMD) distributions in azimuthal and transverse single spin asymmetries. The latest extractions of the Sivers, Collins and transversity functions are also presented.

D Alesio, Umberto

2008-01-01

107

Exploring the nucleon structure from first principles of QCD

International Nuclear Information System (INIS)

Quantum Chromodynamics (QCD) is generally assumed to be the fundamental theory underlying nuclear physics. In recent years there is progress towards investigating the nucleon structure from first principles of QCD. Although this structure is best revealed in Deep Inelastic Scattering, a consistent analysis has to be performed in a fully non-perturbative scheme. The only known method for this purpose are lattice simulations. We first sketch the ideas of Monte Carlo simulations in lattice gauge theory. Then we comment in particular on the issues of chiral symmetry and operator mixing. Finally we present our results for the Bjorken variable of a single quark, and for the second Nachtmann moment of the nucleon structure functions. (orig.)

108

Exploring the nucleon structure from first principles of QCD

Energy Technology Data Exchange (ETDEWEB)

Quantum Chromodynamics (QCD) is generally assumed to be the fundamental theory underlying nuclear physics. In recent years there is progress towards investigating the nucleon structure from first principles of QCD. Although this structure is best revealed in Deep Inelastic Scattering, a consistent analysis has to be performed in a fully non-perturbative scheme. The only known method for this purpose are lattice simulations. We first sketch the ideas of Monte Carlo simulations in lattice gauge theory. Then we comment in particular on the issues of chiral symmetry and operator mixing. Finally we present our results for the Bjorken variable of a single quark, and for the second Nachtmann moment of the nucleon structure functions. (orig.)

Bietenholz, W. [Universidad Nacional Autonoma de Mexico (Mexico). Inst. de Ciencias Nucleares; Cundy, N.; Goeckeler, M. [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)

2010-04-15

109

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

110

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)

111

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

112

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

113

Nucleon structure and properties of dense matter

International Nuclear Information System (INIS)

We consider the properties of dense matter in a framework of the Skyrme soliton model and the chiral bag model. The influence of the nucleon structure on the equation of state of dense matter is emphasized. We find that in both models the energy per unit volume is proportional to n4/3, n being the baryon number density. We discuss the properties of neutron stars with a derived equation of state. The role of many-body effects is investigated. The effect of including higher order terms in the chiral lagrangian is examined. The phase transition to quark matter is studied. 29 refs., 6 figs. (author)

114

A Study of Nucleon Spin Structure from Quantum Chromodynamics

I present an introduction to the field of Quantum Chromodynamics (QCD) with emphasis on nucleon spin structure and perturbative methods. After a somewhat comprehensive overview of perturbative QCD, including the systematics of renormalization, I introduce deeply-inelastic scattering and deeply-virtual Compton scattering along with the nonperturbative distribution functions appearing in these processes. I show how these processes can be used to extract the distribution of longitudinal spin of nucleons, and briefly discuss the complications associated with transverse spin components. There are five appendices which accompany this work, discussing topics ranging from canonical field quantization to dimensional regularization to the structure of several important Lie groups. These appendices are meant to give the reader a certain basic understanding of some of the mathematical details underlying the main text, as well as provide a useful reference. This work was submitted in a slightly different form to the Facul...

Osborne, J

2001-01-01

115

Survey of structures revealed in nucleon-nucleon scattering experiments and dibaryon resonances

International Nuclear Information System (INIS)

Structures appearing in various experimental data (particularly those with polarized beams) in nucleon-nucleon systems are reviewed. Evidence is presented for the existence of dibaryon resonances with an emphasis on a diproton resonance in 3F3 (J/sup P/ = 3-) state. 38 references

116

Nucleon wave function from lattice QCD

Energy Technology Data Exchange (ETDEWEB)

In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)

Warkentin, Nikolaus

2008-04-15

117

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

International Nuclear Information System (INIS)

The author calculates the S matrix for the elastic nucleon-nucleon scattering in the lowest approximation using the quantum theory of nonlinear spinor fields with special emphasis to the ghost configuration of this theory. Introducing a general scalar product a new functional channel calculus is considered. From the results the R and T matrix elements and the differential and integral cross sections are derived. (HSI)

118

Nucleon structure function at small ?

International Nuclear Information System (INIS)

This is a status report on the behaviour of deeply inelastic scattering in the low x region, where a new physics to be expected. It is bound to be theoretical review, since there is no data available at truely small values of x, say x -3. New data from HERA are anticipated and I am viewing on this talk as summary of the theoretical situation in the region of small x, as is just before this new area of physics will be studied experimentally. This is an extended version of the talk which was presented at EP-HEP 91 Conference. (orig.)

119

Nucleon effective mass effects on the Pauli-blocking function

International Nuclear Information System (INIS)

The effects of nucleon effective mass on the Pauli-blocking function are worked out. We have shown that such effects on the quasi-deuteron mechanism of photonuclear absorption are rather relevant. The pauli-blocking function has been evaluated by applying a Monte Carlo calculation particularly suitable for simulation of intranuclear cascade process of intermediate-energy nuclear reactions. The nucleon binding in the photonuclear absorption mechanism is accordingly taken into account. (author)

120

Structure and spin of the nucleon

Directory of Open Access Journals (Sweden)

Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL. TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC, FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.

Avakian H.

2014-03-01

121

Spin structures of the pion and nucleon

Directory of Open Access Journals (Sweden)

Full Text Available We present recent studies on the transverse spin densities of the pion and nucleon within the framework of the chiral quark-(soliton model, based on the calculation of the electromagnetic and tensor form factors of the pion and the nucleon. The results for the transverse spin densities of the quark inside a pion are in good agreement with the recent lattice data, while those of the nucleon show similar features to the lattice results. We also present the first results of the transverse spin densities of the strange quark inside a nucleon.

Nam Seung-il

2012-02-01

122

Nucleon Structure and Hyperon Form Factors from Lattice QCD.

Energy Technology Data Exchange (ETDEWEB)

In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point. to be 1.23(5), consistent with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(2G), consistent with the Adelaide-JLab Collaboration's result. The hyperon {Sigma} and {Xi} axial coupling constants are also performed for the first time in a lattice calculation, g{sub {Sigma}{Sigma}} = 0.441(14) and g{sub {Xi}{Xi}} = -0.277(11).

Lin,H.W.

2007-06-11

123

Nucleon Structure and hyperon form factors from lattice QCD

Energy Technology Data Exchange (ETDEWEB)

In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point to be 1.23(5), consistant with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(26), consistent with the Adelaide-JLab Collaboration's result. The hyperon Sigma and Xi axial coupling constants are also performed for the first time in a lattice calculation, g_SigmaSigma = 0.441(14) and g_XiXi = -0.277(11).

Huey-Wen Lin

2007-06-11

124

Nucleon structure by Lattice QCD computations with twisted mass fermions

International Nuclear Information System (INIS)

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)

125

Taylor-series method for four-nucleon wave functions

International Nuclear Information System (INIS)

Taylor-series method for transforming the infinite or finite well two-nucleon wave functions from individual coordinates to relative and c.m. coordinates, by expanding the single particle shell model wave functions around c.m. of the system, is generalized to four-nucleon wave functions. Also the connections with the Talmi-Moshinsky method for two and four harmonic oscillator wave functions are deduced. For both methods Fortran IV programs for the expansion coefficients have been written and the equivalence of corresponding expressions numerically proved. (author)

126

Photoproduction of nucleon resonances and their structure

International Nuclear Information System (INIS)

Review of available data on radiative decay of non-strange nucleon resonators is presented. The radiative decay amplirude values presented by different authors differ appreciably, which testifies to availability of significant systematic errors. Determination of amplitude of electric quadrupole excitation of ?33(1232) isobar and R11(1440) Roper resonance, arousing great interest due to possibilities of studying features of quark interaction in nucleons and search of hydride (quark-gluon) states, is considered in details. 87 refs.; 5 tabs

127

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

128

Status of Global QCD Analysis and the Parton Structure of the Nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

The current status of global QCD analysis of parton distribution functions of the nucleon is reviewed. Recent progress made in determining various features of the parton structure of the nucleon, as well as outstanding open questions are discussed. These include: the small-$x$ and large-$x$ behavior of the partons, particularly the gluon; the differentiation of $u$ and $d$ quarks; the strangeness sea ($s+\\bar{s}$), the strangeness asymmetry ($s-\\bar{s}$); and the heavy quark...

Tung, Wu-ki

2004-01-01

129

Study of excited nucleons and their structure

International Nuclear Information System (INIS)

Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum. (author)

130

Experiments on nucleon structure with neutrino and charged lepton beams

International Nuclear Information System (INIS)

Lepton scattering is the most basic tool to investigate the nucleon structure. QCD studies of the nucleon structure are an important subject. QCD is a part of standard model of particle physics but still requires careful tests both experimentally and theoretically. The quark-gluon structure of the proton and neutron has been explored by a series of deep inelastic scattering experiments with lepton beams. Neutrino scattering, with the charged current and the neutral current, provides a unique possibility to study anti-quark, strangeness and spin structure. The role of neutrino scattering, when combined with the existing and upcoming data from electron and muon scattering, is described

131

Spin structure of nucleon in QCD: inclusive and exclusive processes

International Nuclear Information System (INIS)

There are two basically independent ways to describe the nucleon spin structure. One is related to quark and gluon spins and another one to their total angular momenta. The latter spin structure may be studied, in principle, in hard exclusive processes

132

Experimental study of the nucleon spin structure

Energy Technology Data Exchange (ETDEWEB)

After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.).

Litmaath, M.F.

1996-05-07

133

Experimental study of the nucleon spin structure

International Nuclear Information System (INIS)

After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.)

134

Structure of nucleons at small distances

International Nuclear Information System (INIS)

We report here the observation of surprisingly simple behaviors in the massive-hadron-pair (m>2 GeV) production from proton-nucleon collisions. With a 28.6-GeV incident proton beam and a pair spectrometer to detect the hadrons, the measured cross section decreases like d2sigma/dxdmproportionale-5/subm/ and can be grouped into three groups: ?-+p; ?++?-, p+p, K-+p; and K-+?+, ?++p. Within a given group the yield is the same to plus-or-minus20%; different groups are separated by a factor of approx.10 from each other

135

It is now widely recognized that a key to unravel the nonperturbative chiral-dynamics of QCD hidden in the deep-inelastic-scattering observables is the flavor structure of sea-quark distributions in the nucleon. We analyze the flavor structure of the nucleon sea in both of the unpolarized and longitudinally polarized parton distribution functions (PDFs) within a single theoretical framework of the flavor SU(3) chiral quark soliton model (CQSM), which contains only one adjustable parameter $\\Delta m_s$, the effective mass difference between the strange and nonstrange quarks. A particular attention is paid to a nontrivial correlation between the flavor asymmetry of the unpolarized and longitudinally polarized sea-quark distributions and also to a possible particle-antiparticle asymmetry of the strange quark distributions in the nucleon. We also investigate the charge-symmetry-violation (CSV) effects in the parton distribution functions exactly within the same theretical framework, which is expected to provide u...

Wakamatsu, Masashi

2014-01-01

136

The spin structure of the nucleon

International Nuclear Information System (INIS)

The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*?? + ?g + Lq + Lg where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and Lq and Lg are the orbital momentum of the quark and the gluon respectively. The ?? contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization ?g/g and the so-called transversity. (A.C.)

137

The spin structure of the nucleon

Energy Technology Data Exchange (ETDEWEB)

The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*{delta}{sigma} + {delta}g + L{sub q} + L{sub g} where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and L{sub q} and L{sub g} are the orbital momentum of the quark and the gluon respectively. The {delta}{sigma} contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization {delta}g/g and the so-called transversity. (A.C.)

Le Goff, J.M

2005-02-15

138

Application of resonance phase for two quasi-stationary states with similar spin and unlike parity is shown to enable to coordinate the experimentally observed signed dependence of P-odd effects in neutron reactions with the theory. The developed approach enables to obtain information on isospin structure of a weak nucleon-nucleon interaction

Smotritskij, L M

2001-01-01

139

Advanced nucleon electromagnetic structure model and charge proton rms radius

International Nuclear Information System (INIS)

Description of the nucleon electromagnetic structure by advanced Unitary and Analytic approach, respecting SU(3) symmetry and analyzing also the recent Mainz MAMI data with impact on the proton charge radius to be compared with the results from the muon hydrogen atom spectroscopy

140

Quark structure of the nucleon and quantum hadrodynamics

International Nuclear Information System (INIS)

The effect of the quark structure of the nucleon on nuclear matter properties is investigated within a ?-?-q model. We have found that in order to reproduce the known properties of normal nuclear matter, the mass of the scalar meson must decrease with increasing nuclear density, in accord with the recent finding of Bernard, Meissner and Zahed. (author)

141

Electromagnetic structure of the nucleons in the Skyrme model

International Nuclear Information System (INIS)

The isoscalar electromagnetic structure of the nucleons is studied within the Skyrme model. The form factors are consistent with the assumption of rotating rigid charge distributions. The use of deuteron data to obtain the isoscalar form factor is discussed; available calculations indicate that the isoscalar charge distribution is consistent with the well-known dipole fit. 8 refs.; 3 figs

142

$pp$ Elastic Scattering at LHC and Nucleon Structure

High energy elastic pp differential cross section at LHC at the c.m. energy 14 TeV is predicted using the asymptotic behavior of sigma-tot(s) and rho(s), and the measured pbar-p differential cross section at sqrt{s}=546 GeV. The phenomenological investigation has progressively led to an effective field theory model that describes the nucleon as a chiral bag embedded in a quark-antiquark condensed ground state. The measurement of pp elastic scattering at LHC up to large |t| >~ 10 GeV^2 by the TOTEM group will be crucial to test this structure of the nucleon.

Islam, M M; Prokudin, A V

2003-01-01

143

Light gluinos and the parton structure of the nucleon

We study the effects of light gluinos with mass below about 1 GeV on the nucleon parton densities and the running of alpha_(S). It is shown that from the available high-statistics DIS data no lower bound on the gluino mass can be derived. Also in the new kinematical region accessible at HERA the influence of such light gluinos on structure f unctions is found to be very small and difficult to detect. For use in more direct searches involving final state signatures we present a radiative estimate of the gluino distribution in the nucleon.

Rückl, R

1994-01-01

144

International Nuclear Information System (INIS)

Understanding the nucleon structure is currently one of the main challenges encountered in nuclear physics. The present work represents a contribution to the study of the nucleon structure and deals, in particular, with the study of the role of strange quarks in the nucleon. The latter can be investigated by determining the strange quark distribution in the nucleon as well as the contribution of the spins of strange quarks to the nucleon spin. This work first presents a measurement of the nucleon spin performed via Deeply Inelastic Scattering (DIS) of a muon beam off polarized proton and deuterium targets. The result is found to be strongly dependent on the quark fragmentation functions into hadrons (FFs), which define the probability that a quark of a given flavour fragments into a final state hadron. The FFs are poorly known, in particular, the FF of strange quark into kaons, which play an important role in the determination of the nucleon spin. In deep inelastic scattering process, the access to the FFs is provided by the hadron multiplicities which, in turn, define the average number of hadrons produced per DIS event. Pion and kaon multiplicities have been extracted versus different kinematic variables, using DIS data collected by deeply inelastic scattering of a 160 GeV/c muons off a deuterium target. A first Leading Order (LO) extraction of the fragmentation functions has then been performed using the measured pion and kaon multiplicities. (author)

145

Fundamental nucleon-nucleon interaction: probing exotic nuclear structure using GEANIE at LANCE/WNR

International Nuclear Information System (INIS)

The initial goal of this project was to study the in-medium nucleon-nucleon interaction by testing the fundamental theory of nuclear structure, the shell model, for nuclei between 8Zr and 100Sn. The shell model predicts that nuclei with ''magic'' (2,8,20,28,40,50, and 82) numbers of protons or neutrons form closed shells in the same fashion as noble gas atoms [may49]. A ''doubly magic'' nucleus with a closed shell of both protons and neutrons has an extremely simple structure and is therefore ideal for studying the nucleon-nucleon interaction. The shell model predicts that doubly magic nuclei will be spherical and that they will have large first-excited-state energies (? 1 to 3 MeV). Although the first four doubly-magic nuclei exhibit this behavior, the N = Z = 40 nucleus, 80Zr, has a very low first-excited-state energy (290 keV) and appears to be highly deformed. This breakdown is attributed to the small size of the shell gap at N = Z = 40. If this description is accurate, then the N = Z = 50 doubly magic nucleus, 100Sn, will exhibit ''normal'' closed-shell behavior. The unique insight provided by doubly-magic nuclei from 80Zr to 100Sn has made them the focus of tremendous interest in the nuclear structure community. However, doubly-magic nuclei heavier than 56Ni become increasingly difficult to form due to the coulomb repulsion between the protons which favors the formation of neutron-richich favors the formation of neutron-rich nuclei. The coulomb repulsion creates a ''proton drip-line'' beyond which the addition of any additional bound protons is energetically impossible. The drip line renders the traditional experimental technique used in their formation, the heavy-ion reaction, less than ideal as a method of forming doubly-magic nuclei beyond 80Zr. The result has been a lack of an new spectroscopic information on doubly magic nuclei in more than a decade [lis87]. Furthermore, uncertainties in reaction dynamics modeling made it difficult for the nuclear science community to predict the cross section or forming these highly-neutron deficient nuclei. Therefore, we decided to try a new approach to forming highly-neutron deficient nuclei with the hope of both gaining spectroscopic information for nuclei near 100Sn, and also gaining insight into reaction dynamics at high (Ex > 200 MeV) incident nucleon energy

146

The pretzelosity distribution function and intrinsic motion of the constituents in nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

The pretzelosity distribution function $h_{1T}^\\perp$ is studied in a covariant the quark-parton model which describes the structure of the nucleon in terms of 3D quark intrinsic motion. This relativistic model framework supports the relation between helicity, transversity and pretzelosity observed in other relativistic models {\\sl without} assuming SU(6) spin-flavor symmetry. Numerical results and predictions for SIDIS experiments are presented.

Efremov, A. V.; Schweitzer, P.; Teryaev, O. V.; Zavada, P.

2008-01-01

147

A bound for the three-quark component of the nucleon wave function

International Nuclear Information System (INIS)

We constrain the probability for the three-quark component of the nucleon wave function by comparing its contribution to the deep-inelastic structure function data for F2(x). The three-quark wave function is constrained by QCD sum rules, i.e., its longitudinal projection has to agree with the Chernyak-Zhitnitski distribution amplitude moments. To relate the distribution amplitudes to F2(x) a specific model for the transverse momentum distribution is needed. We compare two such models and find that both give rather similar results. We conclude that the probability of finding only three quarks in a nucleon could be as large as (3-5)% for experimentally accessible values of Q2. (orig.)

148

Statistical effect in the parton distribution functions of the nucleon

International Nuclear Information System (INIS)

A new and simple statistical approach is performed to calculate the parton distribution functions (PDFs) of the nucleon in terms of light-front kinematic variables. We do not put in any extra arbitrary parameter or corrected term by hand, which guarantees the stringency of our approach. Analytic expressions of the x-dependent PDFs are obtained in the whole x region [0,1], and some features, especially the low-x rise, are more agreeable with experimental data than those in some previous instant-form statistical models in the infinite-momentum frame (IMF). Discussions on heavy-flavored PDFs are also presented

149

International Nuclear Information System (INIS)

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

150

Nuclear energy density functional from chiral pion-nucleon dynamics

International Nuclear Information System (INIS)

We use a recently improved density-matrix expansion (B. Gebremariam, T. Duguet, S.K. Bogner, nucl-th:0910.4979) to calculate the nuclear energy density functional in 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*(?) is identical to the one of Fermi-liquid theory. The strength F?(?) of the (vector ??)2 surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region ?0/2 0. The spin-orbit coupling strength Fso(?) receives contributions from iterated 1?-exchange (of the ''wrong sign'') and from three-nucleon interactions mediated by 2?-exchange with virtual ?-excitation (of the ''correct sign''). In the region around ?0/2 ?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 FJ(?) multiplying the squared spin-orbit density vector J2 is also studied.

151

International Nuclear Information System (INIS)

In the Cloudy Bag Model hadrons are treated as quarks confined in an M.I.T. bag that is surrounded by a cloud of pions. Computations of the charge and magnetism distributions of nucleons and baryons, pion-nucleon scattering, and the strong and electromagnetic decays of mesons are discussed. Agreement with experimental results is excellent if the nucleon bag radius is in the range between 0.8 and 1.1 fm. Underlying qualitative reasons which cause the pionic corrections to be of the obtained sizes are analyzed. If bags are of such reasonably large sizes, nucleon bags in nuclei will often come into contact. As a result one needs to consider whether explicit quark degrees of freedom are relevant for Nuclear Physics. To study such possibilities a model which treats a nucleus as a collection of baryons, pions and six-quark bags is discussed. In particular, the short distance part of a nucleon-nucleon wave function is treated as six quarks confined in a bag. This approach is used to study the proton-proton weak interaction, the asymptotic D to S state ratio of the deuteron, the pp ? d? reaction, the charge density of /sup 3/He, magnetic moments of /sup 3/He and /sup 3/H and, the /sup 3/He-/sup 3/H binding energy difference. It is found that quark effects are very relevant for understanding nuclear properties

152

Implications of Color Gauge Symmetry For Nucleon Spin Structure

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the chromodynamical gauge symmetry in relation to the internal spin structure of the nucleon. We show that 1) even in the helicity eigenstates the gauge-dependent spin and orbital angular momentum operators do not have gauge-independent matrix element; 2) the evolution equations for the gluon spin take very different forms in the Feynman and axial gauges, but yield the same leading behavior in the asymptotic limit; 3) the complete evolution of the gauge-dependent or...

Hoodbhoy, Pervez; Ji, Xiangdong; Lu, Wei

1998-01-01

153

Structure and spin of the nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asym...

Avakian H.

2014-01-01

154

It is now widely recognized that a key to unraveling the nonperturbative chiral dynamics of QCD hidden in the deep-inelastic-scattering observables is the flavor structure of sea-quark distributions in the nucleon. We analyze the flavor structure of the nucleon sea in both the unpolarized and longitudinally polarized parton distribution functions within the flavor SU(3) chiral quark-soliton model, which contains only one adjustable parameter, ?ms, the effective mass difference between the strange and nonstrange quarks. Particular attention is paid to a nontrivial correlation between the flavor asymmetry of the unpolarized and longitudinally polarized sea-quark distributions and also to a possible particle-antiparticle asymmetry of the strange-quark distributions in the nucleon. We also investigate the charge-symmetry-violation effects in the parton distribution functions exactly within the same theoretical framework, which is expected to provide us with valuable information on the relative importance of the asymmetry of the strange and antistrange distributions and the charge-symmetry-violation effects in the valence-quark distributions inside the nucleon in the resolution scenario of the so-called NuTeV anomaly in the extraction of the Weinberg angle.

Wakamatsu, M.

2014-08-01

155

Feasibility studies for nucleon structure measurements with PANDA

The study of nucleon structure is one of the main physics goals of PANDA to be built at the FAIR accelerator complex. The excellent particle identification performance of the PANDA detector will enable measurements of exclusive channels p¯ p ? e+e- and p¯ p ? ?0 J/? ? ?0e+e- to extract the electromagnetic form factors of protons and ?-nucleon Transition Distribution Amplitudes (?-N TDAs). After a brief description of the PANDA apparatus and a method to handle momentum resolution degradation due to Bremsstrahlung, the physics of ?-N TDAs is discussed. An estimate for the expected signal to background ratio for p¯ p ? ?0 J/? ? ?0e+e- that takes into account the main background source is given.

Atomssa, Ermias; Ma, Binsong

2014-11-01

156

Feasibility studies for nucleon structure measurements with PANDA

Directory of Open Access Journals (Sweden)

Full Text Available The study of nucleon structure is one of the main physics goals of PANDA to be built at the FAIR accelerator complex. The excellent particle identification performance of the PANDA detector will enable measurements of exclusive channels p? p ? e+e? and p? p ? ?0 J/? ? ?0e+e? to extract the electromagnetic form factors of protons and ?-nucleon Transition Distribution Amplitudes (?-N TDAs. After a brief description of the PANDA apparatus and a method to handle momentum resolution degradation due to Bremsstrahlung, the physics of ?-N TDAs is discussed. An estimate for the expected signal to background ratio for p? p ? ?0 J/? ? ?0e+e? that takes into account the main background source is given.

Atomssa Ermias

2014-01-01

157

Covariant nucleon wave function with S, D, and P-state components

Energy Technology Data Exchange (ETDEWEB)

Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.

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

2012-05-01

158

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

159

Pion and nucleon structure as probed in the reaction ?±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? 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 xN2 for the ?- data sample. This provides stronger evidence of a rise in the nucleon structure function for xN? and xN used in the Drell-Yan analysis. A definition proposed by Soper has superior invariance properties to that commonly used. An analysis based on this definition yields generally similar results for the pion and nucleon structure function, compared to use of the common definition. However, the pion structure function shows a larger intercept at x?=1 when the definition of Soper is used. (orig.)

160

Studies of nucleon resonance structure in exclusive meson electroproduction

International Nuclear Information System (INIS)

Studies of the structure of excited baryons are key factors to the N* program at Jefferson Lab (JLab). Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electroproduction off protons, along with Quantum Chromodynamics (QCD)-based approaches to the theoretical interpretation of these fundamental quantities. This program will afford access to the dynamics of the nonperturbative strong interaction responsible for resonance formation, and will be crucial in understanding the nature of confinement and dynamical chiral symmetry breaking in baryons, and how excited nucleons emerge from QCD. (author)

161

Low temperature polarized target for spin structure studies of nucleons at COMPASS

In presented thesis we describe concept of Deep Inelastic Scattering of leptons on nucleons in context of nucleon spin structure studies. Both polarized and unpolarized cases are discussed and concept of Transverse Momentum Dependent Parton Distribution Functions (TMD PDF) is introduced. The possibility of TMDs measurement using Semi-inclusive DIS (SIDIS) is described along with related results from COMPASS experiment. The future Drell-Yan programme at COMPASS is briefly mentioned and its importance is presented on the universality test i.e. change of sign of T-odd TMDs when measured in Drell-Yan and SIDIS. The importance of Polarized Target (PT) for spin structure studies is highlighted and principles of Dynamic Nuclear Polarization (DNP) are given using both Solid effect and spin temperature concept. COMPASS experiment is described in many details with accent given to PT. Finally the thermal equilibrium (TE) calibration procedure is described and carried out for 2010 and 2011 physics runs at COMPASS. The av...

Pesek, Michael

162

Contribution of boundness and motion of nucleons to the EMC effect

Digital Repository Infrastructure Vision for European Research (DRIVER)

The kinematical corrections to the structure function of nucleon in nucleus due to the boundness and motion of nucleons arise from the excitation of the doorway states for one-nucleon transfer reactions in the deep inelastic scattering on nuclei.

Birbrair, B. L.; Ryskin, M. G.; Ryazanov, V. I.

2004-01-01

163

Shell-structure influence on the multinucleon transfer in nucleon transfer matrix elements

International Nuclear Information System (INIS)

Full text: An analysis of the experimental data on the charge (mass) distributions of products in nuclear reactions with heavy ions [1], dependence of yield of fragments on their isotope numbers and ones of projectile- and target nuclei [2], and cross sections of the formation of evaporation residues at synthesis of new superheavy elements [3] shows that the individual peculiarities (shell structure, N/Z-ratio) of interacting nuclei play decisive role at formation and evolution of dinuclear system. Therefore, the appropriate microscopic model should be used for the theoretical analysis of the above mentioned effects. The main quantities which must be included into model are the realistic scheme of single-particle states, nucleon separation energy, single-particle matrix elements of nucleon transitions in nuclei and nucleon exchange between them caused by influence of the mean-field of partner-nucleus. In this work the nucleon transfer matrix elements were calculated for the Wood-Saxon potential for spherical nucleus. The eigenvalues and wave functions of single-particle states were obtained by numerical solving Schroedinger's equation. The integral estimation of the matrix elements is found by comparing the calculated width of the charge distributions of the reaction products with the experimental data. In the early paper [4], the same matrix elements were calculated analytically using an approximation for wave functions: authors have used wave functions of the spherical potential well. The numerical values of squares of proton transfer matrix elements found in this work are nearly in coincidence with that presented in [4]. There is a difference between curves of dependencies of the matrix elements under discussion on the relative distance between centres of nuclei when this distance is smaller than sum of nuclei radii

164

Nucleon electromagnetic structure studies in the spacelike and timelike regions

International Nuclear Information System (INIS)

The thesis investigates the nucleon structure probed by the electromagnetic interaction. One of the most basic observables, reflecting the electromagnetic structure of the nucleon, are the form factors, which have been studied by means of elastic electron-proton scattering with ever increasing precision for several decades. In the timelike region, corresponding with the proton-antiproton annihilation into a electron-positron pair, the present experimental information is much less accurate. However, in the near future high-precision form factor measurements are planned. About 50 years after the first pioneering measurements of the electromagnetic form factors, polarization experiments stirred up the field since the results were found to be in striking contradiction to the findings of previous form factor investigations from unpolarized measurements. Triggered by the conflicting results, a whole new field studying the influence of two-photon exchange corrections to elastic electron-proton scattering emerged, which appeared as the most likely explanation of the discrepancy. The main part of this thesis deals with theoretical studies of two-photon exchange, which is investigated particularly with regard to form factor measurements in the spacelike as well as in the timelike region. An extraction of the two-photon amplitudes in the spacelike region through a combined analysis using the results of unpolarized cross section measurements and polarization experiments is presented. Furthermore, predictions of the two-photon exchange effects on the e+p/e-p cross section ratio are given for several new experiments, which are currently ongoing. The two-photon exchange corrections are also investigated in the timelike region in the process p anti p ? e+e- by means of two factorization approaches. These corrections are found to be smaller than those obtained for the spacelike scattering process. The influence of the two-photon exchange corrections on cross section measurements as well as asymmetries, which allow a direct access of the two-photon exchange contribution, is discussed. Furthermore, one of the factorization approaches is applied for investigating the two-boson exchange effects in parity-violating electron-proton scattering. In the last part of the underlying work, the process p anti p??0e+e- is analyzed with the aim of determining the form factors in the so-called unphysical, timelike region below the two-nucleon production threshold. For this purpose, a phenomenological model is used, which provides a good description of the available data of the real photoproduction process p anti p?>?0?.

165

Implications of Color Gauge Symmetry for Nucleon Spin Structure

We study the chromodynamical gauge symmetry in relation to the internal spin structure of the nucleon. We show that 1) even in the helicity eigenstates the gauge-dependent spin and orbital angular momentum operators do not have gauge-independent matrix element; 2) the evolution equations for the gluon spin take very different forms in the Feynman and axial gauges, but yield the same leading behavior in the asymptotic limit; 3) the complete evolution of the gauge-dependent orbital angular momenta appears intractable in the light-cone gauge. We define a new gluon orbital angular momentum distribution $L_g(x)$ which {\\it is} an experimental observable and has a simple scale evolution. However, its physical interpretation makes sense only in the light-cone gauge just like the gluon helicity distribution $\\Delta g(x)$.

Hoodbhoy, P; Lu, W; Hoodbhoy, Pervez; Ji, Xiangdong; Lu, Wei

1999-01-01

166

Nonsinglet spin-dependent structure functions

International Nuclear Information System (INIS)

We investigate the nonsinglet spin-dependent structure function for polarized deep inelastic scattering (DIS) of leptons on nucleons in the next-to-leading-order (NLO) approximation. We perform a fit to extract the polarized parton distribution functions (PPDFs) and the nonsinglet spin structure function using the most recent proton and neutron DIS data. We demonstrate that our results yield good agreement with available observables.

167

Spin structure functions at SLAC E142/E143 experiments

International Nuclear Information System (INIS)

A status report is given on a new experiment performed recently at SLAC on polarized deep inelastic electron scattering. The E143 experiment will provide a precise measurement of the nucleon spin structure functions, allowing further tests of QCD Sum Rules and of the quarks contribution to the spin of the nucleon. (author)

168

Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction

Studies of the structure of excited baryons are key to the N* program at Jefferson Lab. Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever yet achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electroproduction off pro...

Aznauryan, I G; Braun, V; Brodsky, S J; Burkert, V D; Chang, L; Chen, Ch; El-Bennich, B; Cloët, I C; Cole, P L; Edwards, R G; Fedotov, G V; Giannini, M M; Gothe, R W; Lin, Huey-Wen; Kroll, P; Lee, T -S H; Melnitchouk, W; Mokeev, V I; Peña, M T; Ramalho, G; Roberts, C D; Santopinto, E; de Teramond, G F; Tsushima, K; Wilson, D J

2013-01-01

169

Complete spin structure of the pion-nucleon-loop delta self-energy

Digital Repository Infrastructure Vision for European Research (DRIVER)

The complete spin structure of the pion-nucleon-loop contribution to the delta self-energy and dressed propagator is calculated in vacuum, with the most general form of the pion-nucleon-delta vertex. The imaginary parts of the ten Lorentz-scalar coefficients are calculated in closed form, while the real parts are obtained numerically from a dispersion relation. The effect of the pion-nucleon-delta coupling constants and form-factor on the pion-nucleon phase-shift in the spin...

Korpa, C. L.

1997-01-01

170

International Nuclear Information System (INIS)

The authors of this paper performed a separation of the Longitudinal and Transverse structure functions for the 40Ca(e,e'p)39K* reaction in the quasi-elastic region. Their ratio (L/T) is found reduced by about 30% from the Distorted Wave Impulse Approximation prediction. This result is compatible with the quenching of the Coulomb Sum-Rule observed in the inclusive ee' reaction on 40Ca. Since a possible swelling of the nucleon in nuclear matter has been advocated to explain this quenching, we have also measured the 1-dependence of both structure functions to test this hypothesis. The results are not in favor of a large modification of the electromagnetic radius of the nucleon. From the transverse component, an upper limit of 4% can be derived for a possible increase of the magnetic radius

171

Quark Structure of the Nucleon and Angular Asymmetry of Proton-Neutron Hard Elastic Scattering

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate an asymmetry in the angular distribution of hard elastic proton-neutron scattering with respect to 90deg center of mass scattering angle. We demonstrate that the magnitude of the angular asymmetry is related to the helicity-isospin symmetry of the quark wave function of the nucleon. Our estimate of the asymmetry within the quark-interchange model of hard scattering demonstrates that the quark wave function of a nucleon based on the exact SU(6) symmetry predict...

Granados, Carlos G.; Sargsian, Misak M.

2009-01-01

172

Mean-field approach to nuclear structure with semi-realistic nucleon-nucleon interactions

Semi-realistic nucleon-nucleon interactions applicable to the self-consistent mean-field (both Hartree-Fock and Hartree-Fock-Bogolyubov) calculations are developed, by modifying the M3Y interaction. The modification is made so as to reproduce binding energies and rms matter radii of doubly magic nuclei, single-particle levels in $^{208}$Pb, and even-odd mass differences of the Sn isotopes. We find parameter-sets with and without the tensor force. The new interactions are further checked by the saturation properties of the uniform nuclear matter including the Landau-Migdal parameters. By the mean-field calculations, interaction-dependence of the neutron drip line is investigated for the O, Ca and Ni isotopes, and of the single-particle energies for the N=16, 32, 50, 82 and Z=50 nuclei. Results of the semi-realistic interactions including the tensor force are in fair agreement with available experimental data for all of these properties.

Nakada, H

2008-01-01

173

Nucleon--nucleon bremsstrahlung

International Nuclear Information System (INIS)

The nucleon-nucleon bremsstrahlung amplitude through order k depends on the NN wave function within the strong interaction volume and on the two-body magnetic dipole moment, both of which are unknown. Meson exchange currents have been included by several authors to account for parts of the magnetic moment. The wave function is of major interest. It is shown that the cross section at E/sub L/ = 200 MeV is very sensitive to unitary transformations of the reid soft core wavefunction within 1.5 fm. Results are also shown at 42 MeV

174

Studies of the transverse structure of the nucleon at JLab

Energy Technology Data Exchange (ETDEWEB)

Since the earliest measurements in the '70, hadronic physics deals with a number of surprising phenomena that cannot be explained in the framework of perturbative QCD. Examples are the small fraction of the proton spin carried by the valence quark spins, the persistence at high energies of single spin asymmetries and azimuthal asymmetries in unpolarized processes. It is now believed that the answer to these questions may come from the transverse motion of partons inside the nucleon, which is encoded in the Transverse Momentum Dependent (TMD) Parton Distribution Functions. Among the large variety of processes that can be described in terms of TMDs, a major role is played by Semi-Inclusive Deep Inelastic Scattering (SIDIS) reactions, in which, together with the scattered electron, one or more hadrons are detected in the final state. Single and Double Spin Asymmetries are the experimental observables sensitive to TMDs. The identification of the final hadrons allows the tagging of the quark involved in the reaction at the parton level, and then the flavor separation of the relevant TMDs. SIDIS reactions are studied at Jefferson Laboratories since many years and are one of the main items in the physics program after the upgrade of the CEBAF accelerator. The large amount of new data that will be available in few years calls for the implementation of new tools, such as multidimensional analyses and refined techniques of TMDs extraction from the experimental asymmetries. In this talk, the more recent results obtained at 6 GeV will be shown and the future measurements will be discussed.

Mirazita, Marco [INFN, Frascati (Italy)

2014-03-01

175

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)

176

Nucleon Structure from Lattice QCD Using a Nearly Physical Pion Mass

We report the first lattice QCD calculation using the almost physical pion mass mpi=149 MeV that agrees with experiment for four fundamental isovector observables characterizing the gross structure of the nucleon: the Dirac and Pauli radii, the magnetic moment, and the quark momentum fraction. The key to this success is excluding the contributions of excited states. An analogous calculation of the nucleon axial charge governing beta decay fails to agree with experiment, and we discuss possible sources of error.

Green, J R; Krieg, S; Negele, J W; Pochinsky, A V; Syritsyn, S N

2012-01-01

177

A personal view of nucleon structure as revealed by electron scattering

International Nuclear Information System (INIS)

In this article the author charts his scientific career from graduation in 1935. His work on the No I (T1) scintillator detector developed a widely used tool for particle physicists. He later used these detectors in experiments to study nucleon structure via inelastic electron scattering, working mainly with deuterium, alpha particles and beryllium. Proton and neutron ''size'' were early successes of the fifties, with nucleon form factors following after several years' more work. (UK)

178

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

2011-01-01

179

Structure functions extracted from muon pair production at the SPS

International Nuclear Information System (INIS)

Dimuon data provided by ?N interactions were analysed in the framework of the Drell-Yan quark fusion model in order to extract the pion and nucleon structure functions. Our results are compared to the structure functions obtained in other experiments

180

Last Experimental Results Obtained at SLAC on the Nucleon Spin Structure

Recent precise measurements of the spin structure function g sub 1 for proton and for deuteron using deep inelastic scattering of polarized electrons from polarized ammonia targets are presented. The integrals GAMMA sub 1 integral sub 0 sup 1 g sub 1 (x)dx evaluated at the average experimental Q = 3(GeV/c) sup 2 are in agreement with previous results and well below the Ellis-Jaffe sumrule prediction, while the Bjoerken sumrule prediction on GAMMA sub 1 sup p - GAMMA sub 1 sup n is satisfied. The analysis of the results in term of Quark Parton Model implies that the quark carry about a third of the nucleon helicity.

Rock, S E

2003-01-01

181

Polarized Structure Functions: Proton/Deuteron Measurements in Hall C

International Nuclear Information System (INIS)

The study of the nucleon polarized structure functions has matured beyond the inclusive measurements of the past to the investigation of all eight quark distribution functions in the nucleon. Jefferson Lab's Hall C program of polarized structure functions studies started with a measurement of the proton and deuteron spin structure in the resonances at Q2 ? 1.3 [GeV/c]2. This work will be extended for the proton to more than 5 [GeV/c]2 for both DIS and the resonances in the upcoming SANE experiment. SANE will use a novel non-magnetic very large solid angle detector, BETA. Semi-inclusive asymmetries will be measured to determine the flavor composition of the nucleon spin in the recently approved Semi -- SANE experiment. The 11 GeV energy upgrade will open new opportunities to study other functions, such as the transversity, Collins and Sievers functions, using vertical polarized targets

182

Flavor Decomposition of Nucleon Structure at a Neutrino Factory

We explore the possibilities for measuring the quark content of the proton and neutron using neutrino beams produced at a muon storage ring. Because of the nature of the beams, small nuclear targets such as hydrogen and deuterium can be considered, as well as polarized targets. The statistics expected from these targets are calculated using nominal muon storage ring intensities, and the resulting statistical errors on the numerous structure functions available are given, for both polarized and unpolarized targets. It is shown that with a relatively small target, the structure functions F_2, xF_3, xg_1 and xg_5 for neutrinos and antineutrinos on protons and deuterium, either unpolarized or polarized, could be determined with excellent precision over most of the accessible kinematic range.

Ball, R D; McFarland, K S; Ball, Richard D.; Harris, Deborah A.; Farland, Kevin S. Mc

2000-01-01

183

Near Forward pp Elastic Scattering at LHC and Nucleon Structure

High energy proton-proton and antiproton-proton elastic scattering are studied first in a model where the nucleon has an outer cloud and an inner core. Elastic scattering is viewed as due to two processes: a) diffraction scattering originating from cloud-cloud interaction; b) a hard or large |t| scattering originating from one nucleon core scattering off the other via vector meson omega exchange, while their outer clouds interact independently. The omega-exchange amplitude shows that omega behaves like an elementary vector meson at high energy, contrary to a regge pole behavior. This behavior, however, can be understood in the nonlinear sigma-model where omega couples to a topological baryonic current like a gauge boson, and the nucleon is described as a topological soliton. Further investigation shows that the underlying effective field theory model is a gauged linear sigma-model that has not only the pion sector and the Wess-Zumino-Witten action of the nonlinear sigma-model, but also a quark-scalar sector. ...

Islam, M M; Prokudin, A V

2006-01-01

184

Nucleon structure: from high energy elastic scattering and nonlinear ?-model

International Nuclear Information System (INIS)

High energy elastic antipp and pp scattering at the SPS Collider and the ISR have been investigated by my collaborators and me. We find that the elastic scattering can be described as due to two processes: diffraction and hard scattering. The hard scattering originates from the short-distance collision of one nucleon by the other via ? exchange. This description of elastic scattering has led us to the physical picture that the nucleon has an outer cloud and an inner core. The nonLinear ?-model with the Wess-Zumino term included satisfactorily explains many of the important features of our phenomenological description. In particular, this effective QCD framework shows why in our analysis ? behaves as an elementary spin-1 boson and why a ? NN form factor occurs. Our investigation, in turn, supports the basic notion of the nonlinear ?-model that the nucleon is a soliton carrying a topological baryonic charge. It further indicates that the soliton is accompanied by a quark-antiquark cloud

185

Contribution of vector mesons to F2 structure function

In recent years we have used meson cloud to investigate polarized and unpolarized nucleon struc- ture functions [1-6]. Here we present the contribution of vector mesons along with their baryon octets and decuplets counterparts to the meson cloud [1]. For the bare nucleon we use a quark- diquark model. Our work has shown that it is necessary for the core nucleon to have a spin-1 diquark component. In this work we will use superposition of spin-0 and spin-1 diquarks as the core nucleon to calculate quark distribution functions. Then, using pQCD, an initial gluon distri- bution is generated inside the core nucleon. The physical nucleon is assumed to be a superposition of the bare nucleon plus the virtual light-cone Fock states of the baryon-meson pairs. The initial distributions are evolved using DGLAP equations. The F2 structure functions calculated from the evolved distributions are compared with NMC and Zeus results along with a CTEQ fits. Also, we will show that the meson cloud is a contributing factor to sea quark asymmetry and one needs both pseuoscalar mesons and vector mesons to account fully for the Gottfried sum-rule violation.

Zamani, F.

186

Experimental Studies of Quark-Gluon Structure of Nucleons and Nuclei

Energy Technology Data Exchange (ETDEWEB)

The NMSU group has a lengthy history in the study of the nucleon structure and in particular its spin structure in terms of its fundamental constituents. This line of research is continuing in our current involvement in experiments at Brookhaven National Lab and the Thomas Jefferson National Accelerator Facility.

Kyle, Gary

2004-12-17

187

Shell structure and few-nucleon removal in intranuclear cascade

It is well known that intranuclear-cascade models generally overestimate the cross sections for one-proton removal from heavy, stable nuclei by a high-energy proton beam, but they yield reasonable predictions for one-neutron removal from the same nuclei and for one-nucleon removal from light targets. We use simple shell-model calculations to investigate the reasons of this deficiency. We find that a correct description of the neutron skin and of the energy density in the nuclear surface is crucial for the aforementioned observables. Neither ingredient is sufficient if taken separately.

Mancusi, Davide; Carbonell, Jaume; Cugnon, Joseph; David, Jean-Christophe; Leray, Sylvie

2014-01-01

188

Lattice investigations of nucleon structure at light quark masses

International Nuclear Information System (INIS)

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. (orig.)

189

Impact of the recent Jefferson lab data on the structure of the nucleon

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The simultaneous fit of proton ratio m pG Ep/G Mp, qF2p/F1p to the recent experimental data and static properties of the nucleon is studied within a light-front model with different spin coupling schemes and wave functions. The position of the zero of proton electric form factor is sensitive to the [...] presence of a hard constituent quark component in the nucleon wave function. The fitting of the new data for the ratios is achieved with a hard momentum scale about 4-5 GeV.

W.R.B. de, Araújo; T., Frederico; M., Beyer; H.J., Weber.

2004-03-01

190

Impact of the recent Jefferson lab data on the structure of the nucleon

International Nuclear Information System (INIS)

The simultaneous fit of proton ratio ?pGEp/GMp, qF2p/F1p to the recent experimental data and static properties of the nucleon is studied within a light-front model with different spin coupling schemes and wave functions. The position of the zero of proton electric form factor is sensitive to the presence of a hard constituent quark component in the nucleon wave function. The fitting of the new data for the ratios is achieved with a hard momentum scale about 4-5 GeV. (author)

191

Compton Scattering and the Spin Structure of the Nucleon at Low Energies

We analyze polarized Compton scattering which provides information on the spin-structure of the nucleon. For scattering processes with photon energies up to 100 MeV the spin-structure dependence can be encoded into four independent parameters-the so-called spin-polarizabilities gamma_i, i=1...4 of the nucleon, which we calculate within the framework of the "small scale expansion" in baryon chiral perturbation theory. Specific application is made to "forward" and "backward" spin-polarizabilities.

Hemmert, T R; Kambor, J; Knöchlein, G; Hemmert, Thomas R.; Holstein, Barry R.; Kambor, Joachim; Knoechlein, Germar

1998-01-01

192

Neutrino charged-current structure functions

International Nuclear Information System (INIS)

Charged current total cross sections and structure functions were extracted from neutrino and antineutrino data taken with the Fermilab narrow band beam. The cross section results are sigma/sup nu//E = 0.701 +- 0.004 +- 0.025 x 10-38 cm2/GeV and sigma/sup nu-bar//E = 0.350 +- 0.04 +- 0.022 x 10-38 cm2/GeV. The structure functions exhibit scaling violations. A comparison with structure functions obtained in muon scattering experiments indicates a ratio consistent with 18/5 within the systematic errors of both experiments. The structure function function xF3 is used to test the Gross-Llewellyn Smith sum rule. The data is in agreement with the prediction of 3 for the number of valence quarks on the nucleon

193

International Nuclear Information System (INIS)

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)

194

While the ordinary structure function in turbulence is concerned with the statistical moments of the velocity increment Deltau measured over a distance r , the inverse structure function is related to the distance r where the turbulent velocity exits the interval Deltau. We study inverse structure functions of wind-tunnel turbulence which covers a range of Reynolds numbers Re(lambda) = 400-1100. We test a recently proposed relation between the scaling exponents of the ordinary structure functions and those of the inverse structure functions [S. Roux and M. H. Jensen, Phys. Rev. E 69, 16309 (2004)]. The relatively large range of Reynolds numbers in our experiment also enables us to address the scaling with Reynolds number that is expected to highlight the intermediate dissipative range. While we firmly establish the (relative) scaling of inverse structure functions, our experimental results fail both predictions. Therefore, the question of the significance of inverse structure functions remains open. PMID:15903570

Pearson, Bruce R; van de Water, Willem

2005-03-01

195

The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N2LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.

Gebremariam, B.; Bogner, S. K.; Duguet, T.

2011-02-01

196

International Nuclear Information System (INIS)

The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in (arXiv:0910.4979) by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N2LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.

197

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

198

The CP violation structure of nucleon from QCD ?--term and color-EDM

International Nuclear Information System (INIS)

The most general and consistent with QCD description of CP-odd structure of nucleon is obtained in the framework of Chiral Perturbation Theory (?PT). The goal is to reduce the theoretical uncertainties of phenomenological approaches and to obtain a more precise description of static properties of nucleon which also are an input for CP-odd properties of nuclei. This is better suitable to the analyses of results of nuclear high precision measurements program. In order to search for hints of physics beyond Standard Model (SM), this program is looking for tiny deviations from SM predictions or measuring very small observables. In the case of Electric Dipole Moments of nucleons, SM predictions are far below the current experimental limits, but at the reach of new physics predictions as for the ?-QCD source for strong CP-violation. The ?PT is a theory for the physics below MQCD scale where the underlining degrees of freedom are not manifested and in the case of SU(2) sector one has effective degrees of freedom of pions and nucleons instead of quarks and gluons degrees of freedom . Following QCD principles ?PT organizes the interactions in order of decreasing importance: the chiral expansion. The properties of nucleon are evaluated up to sub-leading order in chiral expansion. At the leading order the contribution to Electric Dipole Form Factor of nucleon is pure isovector and it gives rise to null contribution to Electric Dipole Moment of deuteron. The isoscalar contribution appears at sub-leading order. In the case of Electric Dipole Moment of deuteron the CP-odd ?N contribution stemming from ?--term has an expected size of |dd| -4?- e fm. The Schiff moment of nucleon is also obtained. (author)

199

Nuclear energy density functional from chiral pion-nucleon dynamics revisited

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 $1\\pi$-exchange, iterated $1\\pi$-exchange, and irreducible $2\\pi$-exchange with intermediate $\\Delta$-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass $M^*(\\rho)$ entering the energy density ...

Kaiser, N.; Weise, W.

2009-01-01

200

Recent COMPASS results on the nucleon longitudinal spin structure and QCD fits

Directory of Open Access Journals (Sweden)

Full Text Available The latest measurements of the proton longitudinal spin structure function, ?1p, in the deep inelastic (DIS regime are presented. They improve the statistical accuracy of the existing data and extend the kinematic domain to a lower value of x and higher values of Q2. A global NLO QCD fit of all ?1 world data on the proton, deuteron and neutron has been achieved. The results give a quantification of the quark spin contribution to the nucleon spin, 0.26 < ?? < 0.34 at 3 (GeV/c2 in M?S? scheme. The errors are dominated by the uncertainty on the shape of the functional forms assumed in the fit. A new verification of the fundamental Bjorken sum rule is obtained at a 9% level, using only COMPASS ?1 proton and deuteron measurements. Preliminary results of a reevaluation of the gluon polarization ??/? are presented. The analysis is based on double spin asymmetry of high-pT hadron production cross-sections in the DIS regime. A positive value of ???/?? = 0.113 ± 0.038 ± 0.035 is obtained at leading order at x ~ 0.1. In parallel, the double spin asymmetry in the photoproduction regime is also studied. Finally, preliminary results on quark fragmentation functions into pions extracted from a LO fit of pion multiplicities in semi-inclusive DIS are presented.

Andrieux Vincent

2014-01-01

201

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

202

Low energy structure of the nucleon from chiral effective field theory

Directory of Open Access Journals (Sweden)

Full Text Available We present some updated results regarding the scalar and electromagnetic structure of the nucleon obtained by the relativistic formulation of chiral effective field theory with baryons. We compare them with previous determinations available in the literature, and show their relevance for searches of physics beyond the standard model in the low energy frontier.

Alarcón Jose Manuel

2014-01-01

203

Effect of the nucleon structure in the quasi-elastic ?N-scattering

International Nuclear Information System (INIS)

Peculiarities in cross sections of ?N-scattering (weak maXima and minima) are interpreted as manifestation of inelastic scattering processes on structural elements of a nucleon. Relation of cross section peculiarities in the t-channel of elastic NN- and quasi-elastic ?nN-scattering is disolvsed

204

The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam {\\it et al.} to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N$^2$LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a cutoff-dependent coupling {\\it constant} arising from zero-range contact interactions and a cutoff-independent coupling {\\it function} of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions...

Gebremariam, B; Duguet, T

2010-01-01

205

Energy Technology Data Exchange (ETDEWEB)

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)

Harraud, P.A.

2010-11-15

206

Photon structure function revisited

Digital Repository Infrastructure Vision for European Research (DRIVER)

The flux of papers from electron positron colliders containing data on the photon structure function ended naturally around 2005. It is thus timely to review the theoretical basis and confront the predictions with a summary of the experimental results. The discussion will focus on the increase of the structure function with x (for x away from the boundaries) and its rise with log Q**2, both characteristics beeing dramatically different from hadronic structure functions. Comp...

Berger, Ch

2014-01-01

207

International Nuclear Information System (INIS)

This book is an introduction to the interactions of nucleons with special regards to their contribution to nuclear forces. After a general description of the nuclear structure as a configuration of many nucleons the properties and interactions of nucleons are described with an excursion to the fundamental processes governing them. Then nuclear energy levels are considered. Thereafter nuclear energy-level transitions are described in the framework of the governing elementary processes. Finally nuclear reactions are considered in this framework. This book is suited as a supplement to a textbook in nuclear physics for students, who want to get a deeper insight in the fundamental processes in nuclei. (HSI)

208

Perturbative evolution of polarized structure functions

We review the perturbative evolution of the polarized structure functions g_1 and their associated parton distribution functions, with particular emphasis on the anomalous coupling of the first moment of the polarized gluon distribution. We also describe the small x behaviour of polarized parton distributions, contrasting it with that of the unpolarized distributions. We then explain how this theoretical analysis affects the extraction of the singlet axial charge from experimental data on g_1, and show that it may be possible to use such data to infer the existence of polarized gluons in the nucleon.

Ball, R D

1997-01-01

209

Nuclear medium modification of the F2 structure function

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the nuclear effects in the electromagnetic structure function F2(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 over deuteron structure function are obtained and compared with the recen...

Athar, M. Sajjad; Simo, I. Ruiz; Vacas, M. J. Vicente

2009-01-01

210

Spin-dependent Nucleon Structure Studies at MIT/Bates

International Nuclear Information System (INIS)

We present preliminary results from recent measurements of the proton, neutron and deuterium electro-magnetic form factors obtained by the BLAST collaboration at the MIT/Bates Linear Accelerator Facility. BLAST (Bates Large Acceptance Spectrometer Toroid) is a large-acceptance multi-purpose detector dedicated to studies of exclusive spin-dependent electron scattering from internal polarized targets. BLAST makes use of stored electron beam currents in excess of 150 mA with a 60-70% polarization. The electron beam is let through a 15 mm diameter, 60 cm long open-ended storage cell which is fed with ultra-pure, high-polarization H1,D1 gas from an Atomic Beam Source. The target polarization can be rapidly reversed between different vector and tensor target states, thus minimizing systematic uncertainties. The target spin can be oriented to any in-plane direction via a set of Helmholtz coils. Target polarizations in the storage cell of up to 80% (vector) and 70% (tensor) have been routinely achieved over a period of several months. Our data on the D-vector(e-vector,e'n) reaction off vector polarized deuterium allow for a unique extraction of the neutron charge form factor GEn. At same time, complementary measurements of GMn, T20 and the spin-dependent nucleon momentum distributions in deuterium are obtained via the D-vector(e-vector,e'), D(e-vector,e'd) and D(e-vector,e'p) reactions. In addition, BLAST data on vector polari. In addition, BLAST data on vector polarized hydrogen will provide novel measurements of the GE/GM form-factor ratio on the proton as well as of the spin-dependent electro-excitation of the ?(1232) resonance. Such comprehensive program on few body physics is now well underway and preliminary data will be presented

211

When the new data on polarised lepton nucleon scattering are compared at the same value of $Q^2$ and with a common set of assumptions, a consistent picture of the spin content of the nucleon begins to emerge. Higher order effects in $0(\\alpha_s)$, higher twist effects, modern data on unpolarised structure functions and an updated value for F/D are all important in analysing the data. The detailed x dependences of the polarisation asymmetry in the valence quark region are shown to confirm 20 year old predictions of the quark model and I argue that these are an important ingredient in decoding the nucleon spin puzzle.

Close, Francis Edwin

1993-01-01

212

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

213

International Nuclear Information System (INIS)

This book contains the lectures given at the International Summer School on Structure and Stability of Nucleon and Nuclear Systems held in Predeal, Romania, in the period August 24 - September 5, 1998. The program of the school covered the following six topics: Nuclear structure (11 lectures); Dynamics of nuclear systems explored by collisions with various projectiles at different energies (8 lectures); Light and heavy cluster emission, cold and ternary fission (4 lectures); ?+-, 2???, 0??? and other neutrino processes; Structure and stability of nucleons (3 lectures); Nuclear matter under exotic conditions (2 lectures). Related to these topics were 17 short communications whose full text can be obtained on request from the authors or from a special issue of Romanian Journal of Physics. The aim of the school was concentrated on the behaviour of nuclear systems under extreme conditions, to understand newly discovered properties of complex nuclei and nucleons, to approach subjects bordering nuclear and particle physics, to identify specific phenomena taking place under conditions met presumably in stars, to investigate the newly explored systems of very short half-life. Exotic phenomena like halo structure of some light nuclei, superdeformation, structure of nuclei lying far from the stability line, specific properties of hot nuclei were also considered in many lectures

214

Polarised structure functions in the parton model

International Nuclear Information System (INIS)

It is shown that a covariant form of the parton model is necessary for consistent predictions of the nucleon spin structure functions. Sum rules relating g2 to g1 are derived and the limits of their applicability discussed. The measurement of g1 is shown to give a direct estimate of the mean kT as a function of x yielding values consistent with experiment and with an independent estimate we derive from a covariant formulation of the parton model for the unpolarised structure functions. With the assumption of dominance of k2 ? O, it is shown that the polarised and unpolarised covariant parton distributions themselves as functions of p·k can be extracted from the data, giving a complete specification of the covariant relativistic parton model. (author)

215

Nucleon Structure In Lattice QCD With Dynamical Domain-wall Fermions Quarks

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)^3. Despite the small volume, the ratio of the isovector vector and axial charges g_A/g_V and that of structure function moments _{u-d}/_{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 ab...

Lin, H W; Lin, Huey-Wen; Ohta, Shigemi

2006-01-01

216

International Nuclear Information System (INIS)

For lattice operators that are relevant to the calculation of moments of nucleon structure functions we investigate the transformation properties under the hypercubic group. We give explicit bases of irreducible subspaces for tensors of rank ?4. (orig.)

217

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

LIN H.-W.; OHTA, S.

2006-10-02

218

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

Huey-Wen Lin; Shigemi Ohta

2006-07-23

219

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)

220

Studies of partonic transverse momentum and spin structure of the nucleon

Energy Technology Data Exchange (ETDEWEB)

The investigation of the partonic degrees of freedom beyond collinear approximation (3D description) has been gained increasing interest in the last decade. The Thomas Jefferson National Laboratory, after the CEBAF upgrade to 12 GeV, will become the most complete facility for the investigation of the hadron structure in the valence region by scattering of polarized electron off various polarized nucleon targets. A compendium of the planned experiments is here presented.

Contalbrigo, Marco M. [INFN, Ferrara, Italy

2014-06-01

221

Relativistic Structure of the Nucleon Self-Energy in Asymmetric Nuclei

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Dirac structure of the nucleon self-energy in asymmetric nuclear matter cannot reliably be deduced from the momentum dependence of the single-particle energies. It is demonstrated that such attempts yield an isospin dependence with even a wrong sign. Relativistic studies of finite nuclei have been based on such studies of asymmetric nuclear matter. The effects of these isospin components on the results for finite nuclei are investigated.

Ulrych, S.; Mu?ther, H.

1997-01-01

222

Towards the results of global analysis of data on nucleon electromagnetic structure

International Nuclear Information System (INIS)

Peculiar features of the recent global analysis of data on the nucleon electromagnetic structure are discussed on the detail in order to reconsider reliability of the predicted result that the electron-positron annihilation into a neutron-antineutron cross-section is considerably larger that the cross-section of the electron-positron annihilation into a proton-antiproton pair. 14 refs.; 3 figs.; 3 tabs

223

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

224

Neutron Structure Functions From Nuclear Data

Digital Repository Infrastructure Vision for European Research (DRIVER)

The spin-averaged structure function of the neutron, F_2^n, is extracted from recent deuteron data, taking into account the small but significant corrections due to nuclear effects in the deuteron. At small x, the F_2D/F_2p ratio measured by the New Muon and Fermilab E665 Collaborations is interpreted to suggest a small amount of shadowing in deuterium, which acts to enhance F_2^n for x < 0.1. A careful treatment of Fermi motion, binding and nucleon off-shell effects in the ...

Melnitchouk, W.; Thomas, A. W.

1996-01-01

225

Nuclear medium effects in structure functions

International Nuclear Information System (INIS)

We discuss the nuclear-medium effects in the weak structure functions F2(x,Q2) and F3,(x,Q2) in the charged current neutrino and antineutrino induced deep inelastic reactions in some nuclei which are being used in the present or proposed neutrino oscillation experiments. Our study of the medium effects has been done using relativistic nuclear spectral functions which incorporates Fermi motion, binding energy and nucleon correlations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, the results for the differential cross section have been obtained and compared with some of the available experimental data.

226

Chromatin Structure and Function

The Third Edition of Chromatin: Structure and Function brings the reader up-to-date with the remarkable progress in chromatin research over the past three years. It has been extensively rewritten to cover new material on chromatin remodeling, histone modification, nuclear compartmentalization, DNA methylation, and transcriptional co-activators and co-repressors. The book is written in a clear and concise fashion, with 60 new illustrations. Chromatin: Structure and Function provides the reader with a concise and coherent account of the nature, structure, and assembly of chromatin and its active

Wolffe, Alan P

1999-01-01

227

Photon structure function revisited

The flux of papers from electron positron colliders containing data on the photon structure function ended naturally around 2005. It is thus timely to review the theoretical basis and confront the predictions with a summary of the experimental results. The discussion will focus on the increase of the structure function with x (for x away from the boundaries) and its rise with log Q**2, both characteristics beeing dramatically different from hadronic structure functions. Comparing the data with a specific QCD prediction a new determination of the QCD coupling coupling constant is presented. The agreement of the experimental observations with the theoretical calculations of the real and virtual photon structure is a striking success of QCD.

Berger, Ch

2014-01-01

228

Unified approach to structure factors and neutrino processes in nucleon matter

International Nuclear Information System (INIS)

We present a unified approach to neutrino processes in nucleon matter based on Landau's theory of Fermi liquids that includes one and two quasiparticle-quasihole pair states as well as mean-field effects. We show how rates of neutrino processes involving two nucleons may be calculated in terms of the collision integral in the Landau transport equation for quasiparticles. Using a relaxation time approximation, we solve the transport equation for density and spin-density fluctuations and derive a general form for the response functions. We apply our approach to neutral-current processes in neutron matter, where the spin response function is crucial to the calculation of neutrino elastic and inelastic scattering and neutrino-pair bremsstrahlung and absorption from strongly interacting nucleons. We calculate the relaxation rates using modern nuclear interactions and including many-body contributions, and find that rates of neutrino processes are reduced compared with estimates based on the one-pion exchange interaction, which is used in current simulations of core-collapse supernovae

229

Nucleon structure from 2+1 flavor domain wall QCD at nearly physical pion mass

The RBC and UKQCD collaborations have been investigating hadron physics in numerical lattice quantum chromodynamics (QCD) with (2+1) flavors of dynamical domain wall fermions (DWF) quarks that preserves continuum-like chiral and flavor symmetries. The strange quark mass is adjusted to physical value via reweighting and degenerate up and down quark masses are set as light as possible. In a recent study of nucleon structure we found a strong dependence on pion mass and lattice spatial extent in isovector axialvector-current form factors. This is likely the first credible evidence for the pion cloud surrounding nucleon. Here we report the status of nucleon structure calculations with a new (2+1)-flavor dynamical DWF ensembles with much lighter pion mass of 180 and 250 MeV and a much larger lattice spatial exent of 4.6 fm. A combination of the Iwasaki and dislocation-suppressing-determinant-ratio (I+DSDR) gauge action and DWF fermion action allows us to generate these ensembles at cutoff of about 1.4 GeV while ke...

Ohta, Shigemi

2011-01-01

230

Probing spin-1 diquarks in deep inelastic structure functions

International Nuclear Information System (INIS)

Within the scope of a new diquark model for deep inelastic structure functions presented by us recently we use the existing data on F1sup(ep)(x,Q2) to learn about the admixture of spin-1 diquarks in nucleons. It turns out that they are so rare, heavy and extended compared to spin-0 diquarks that they are presumably accidental and not dynamical. Their number and form factors can be understood qualitatively within this picture. Still, the spin-1 diquarks give interesting structures in data and, together with quarks and spin-0 diquarks, carry enough momentum to account for the full nucleon energy. A gluon component is hence not needed in the nucleon. (orig.)

231

What we can learn about nucleon spin structure from recent data

International Nuclear Information System (INIS)

We have used recent data from the CERN and SLAC to extract information about nucleon spin structure. We find that the SMC proton data on ?01g1pdx, the E142 neutron data on ?01g1ndx, and the deuteron data from the SMC and E143 give different results for fractions of the spin carried by each of the constituents. These appear to lead to two different and incompatible models for the polarized strange sea. The polarized gluon distribution occurring in the gluon anomaly does not have to be large in order to be consistent with either set of experimental data. However, it appears that the discrepancies in the implications of these data cannot be resolved with any simple theoretical arguments. We conclude that more experiments must be performed in order to adequately determine the fraction of spin carried by each of the nucleon constituents. copyright 1997 The American Physical Society

232

Energy Technology Data Exchange (ETDEWEB)

The authors calculate properties of A = 6 system using the accurate charge-dependent nucleon-nucleon (NN) potential at fourth order of chiral perturbation theory. By application of the ab initio no-core shell model (NCSM) and a variational calculation in the harmonic oscillator basis with basis size up to 16 {h_bar}{Omega} they obtain the {sup 6}Li binding energy of 28.5(5) MeV and a converged excitation spectrum. Also, they calculate properties of {sup 10}B using the same NN potential in a basis space of up to 8 {h_bar}{Omega}. The results are consistent with results obtained by standard accurate NN potentials and demonstrate a deficiency of Hamiltonians consisting of only two-body terms. At this order of chiral perturbation theory three-body terms appear. It is expected that inclusion of such terms in the Hamiltonian will improve agreement with experiment.

Navratil, P; Caurier, E

2003-10-14

233

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

234

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

235

Deep Inelastic Structure Functions in a Covariant Spectator Model

Digital Repository Infrastructure Vision for European Research (DRIVER)

Deep-inelastic structure functions are studied within a covariant scalar diquark spectator model of the nucleon. Treating the target as a two-body bound state of a quark and a scalar diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the solutions of the BSE.

Kusaka, K.; Piller, G.; Thomas, A. W.; Williams, A. G.

1996-01-01

236

Deep-inelastic structure functions in a covariant spectator model

International Nuclear Information System (INIS)

Deep-inelastic structure functions are studied within a covariant scalar diquark spectator model of the nucleon. Treating the target as a two-body bound state of a quark and a scalar diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the solutions of the BSE. copyright 1997 The American Physical Society

237

Deep Inelastic Structure Functions in a Covariant Spectator Model

Deep-inelastic structure functions are studied within a covariant scalar diquark spectator model of the nucleon. Treating the target as a two-body bound state of a quark and a scalar diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the solutions of the BSE.

Kusaka, K; Thomas, A W; Williams, A G

1997-01-01

238

A-dependence of weak nuclear structure functions

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 str...

Haider, H.; Simo, I. Ruiz; Athar, M. Sajjad

2013-01-01

239

EM vs Weak Structure Functions in DIS processes

Digital Repository Infrastructure Vision for European Research (DRIVER)

We obatin the ratio $F_i^A/F_i^{D}$(i=2,3, A=Be, C, Fe, Pb; D=Deuteron) in the case of weak and electromagnetic nuclear structure functions. For this, relativistic nuclear spectral function which incorporate the effects of Fermi motion, binding and nucleon correlations is used. We also consider the pion and rho meson cloud contributions and shadowing and antishadowing effects.

Athar, M. Sajjad; Haider, H.; Simo, I. Ruiz; Vacas, M. J. Vicente

2013-01-01

240

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

241

Monte Carlo Generators for Studies of the 3D Structure of the Nucleon

Energy Technology Data Exchange (ETDEWEB)

Extraction of transverse momentum and space distributions of partons from measurements of spin and azimuthal asymmetries requires development of a self consistent analysis framework, accounting for evolution effects, and allowing control of systematic uncertainties due to variations of input parameters and models. Development of realistic Monte-Carlo generators, accounting for TMD evolution effects, spin-orbit and quark-gluon correlations will be crucial for future studies of quark-gluon dynamics in general and 3D structure of the nucleon in particular.

Avagyan, Harut A. [JLAB

2015-01-01

242

Monte Carlo Generators for Studies of the 3D Structure of the Nucleon

Extraction of transverse momentum and space distributions of partons from measurements of spin and azimuthal asymmetries requires development of a self consistent analysis framework, accounting for evolution e?ects, and allowing control of systematic uncertainties due to variations of input parameters and models. Development of realistic Monte-Carlo generators, accounting for TMD evolution effects, spin-orbit and quark-gluon correlations will be crucial for future studies of quark-gluon dynamics in general and 3D structure of the nucleon in particular.

Avakian, Harut

2015-01-01

243

Hyperfine structure of ground-state nucleons in chiral quark model

Hyperfine structure of ground-state nucleons is studied by checking the isospin breaking effect due to the non-zero differences of mass and electromagnetic interaction between the up and down quarks. It is shown using chiral nonlinear quark model that the isospin breaking corrections to the baryon mass are of the order of one percent relatively to hadronic energies. The computed mass splittings due to the hyperfine strong and the electromagnetic corrections are in good agreement with the recent data of the baryon mass splitings.

Jia, Duojie; Dang, Wen-Bo; Zhao, Xing-Wen

2015-10-01

244

Nuclear structure functions at low-x in a holographic approach

International Nuclear Information System (INIS)

Nuclear effects in deep inelastic scattering at low x are phenomenologically described changing the typical dynamical and/or kinematical scales characterizing the free nucleon case. In a holographic approach, this rescaling is an analytical property of the computed structure function F2(x, Q2). This function is given by the sum of a conformal term and of a contribution due to quark confinement, depending on IR hard-wall parameter z0 and on the mean square distances, related to a parameter Q', among quarks and gluons in the target. The holographic structure function per nucleon in a nucleus A is evaluated showing that a rescaling of the typical nucleon size, z0 and Q', due to nuclear binding, can be reabsorbed in a Q2-rescaling scheme. The difference between neutron and proton structure functions and the effects of the longitudinal structure functions can also be taken into account. The obtained theoretical results favorably compare with the experimental data. (orig.)

245

The observation of the violation of Lam-Tung relation in the $\\pi N$ Drell-Yan process triggered many theoretical speculations. The TMD Boer-Mulders functions characterizing the correlation of transverse momentum and transverse spin for partons in unpolarized hadrons could nicely account for the violation. The COMPASS experiment at CERN will measure the angular distributions of dimuons from the unpolarized Drell-Yan process over a wide kinematic region and study the beam particle dependence. Significant statistics is expected from a successful run in 2015 which will bring further understanding of the origin of the violation of Lam-Tung relation and of the partonic transverse spin structure of the nucleon.

Chang, Wen-Chen

2015-01-01

246

Spin Structure Functions from Electron Scattering

International Nuclear Information System (INIS)

The spin structure of the nucleon can play a key testing ground for Quantum Chromo-Dynamics (QCD) at wide kinematic ranges from smaller to large four momentum transfer Q2. The pioneering experiments have confirmed several QCD sum rules at high Q2 where a perturbative picture holds. For a full understanding of QCD at various scales, various measurements were made at intermediate and small Q2 region and their interpretation would be a challenging task due to the non-perturbative nature. Jefferson Lab has been one of the major experimental facilities for the spin structure with its polarized electron beams and various polarized targets. A few QCD sum rules have been compared with the measured spin structure functions g1(x, Q2) and g2(x, Q2) at low Q2 and surprising results have been obtained for the spin polarizabilities, ?0 and (delta)LT . As for the proton spin structure functions, the lack of data for g2(x,Q2) structure functions has been complemented with a new experiment at Jefferson Lab, SANE. The results from SANE will provide a better picture of the proton spin structure at a wide kinematic range in x and Q2.

247

Digital Repository Infrastructure Vision for European Research (DRIVER)

We review the theory and phenomenology of deep inelastic polarized lepton-nucleon scattering in the light of recent data with a deuteron target from the SMC at CERN and a Helium 3 target from the E142 experiment at SLAC. After including higher-order perturbative QCD corrections, mass corrections and updated estimates of higher-twist effects, we find good agreement with the basic Bjorken sum rule, and extract a consistent set of values for the quark contributions to the proto...

Mallot, Gerhard K.

1992-01-01

248

International Nuclear Information System (INIS)

Nucleon structure functions have been extracted from a large sample of neutrino and anti-neutrino inclusive charged-current events. These data were obtained over the period from June, 1979 through January, 1980, using the Lab E detector in the N30 dichromatic beam at Fermilab (experiment E616). The methods used to extract structure functions from the data are detailed. An analysis of sources of systematic error on these results is made. A comparison of the results for F2 is made with other measurements from both neutrino and charged lepton scattering. Differences in overall normalization and in the x dependence of the structure function are found. The mean square quark charge rule from the quark-parton model is confirmed at the 10% level. Quantum Chromodynamics (QCD) predicts a pattern of scaling violations in F2 which is observed in these results. This has been quantified by making fits to the data using numerical integration of the Altarelli-Parisi equations. The value of ?/sub MS/, the QCD scale parameter, is found to be 340 +/- 100 +/- 60MeV with an additional uncertainty of +/-50MeV due to the unknown form of the gluon distribution

249

High energy proton-proton elastic scattering at the Large Hadron Collider and nucleon structure

To gain insight into the structure of the nucleon, we pursue the development of the phenomenological model of Islam et al. (IIFS model) for high energy elastic pp and p¯p scattering. We determine the energy dependence of the parameters of the IIFS model using the available elastic differential cross section data from SPS Collider and Tevatron and the known asymptotic behavior of sigmatot (s) and rho(s) from dispersion relation calculations and more recent analyses of Cudell et al. (COMPETE Collaboration). Next, we incorporate a high energy elastic valence quark-quark scattering amplitude into the model based on BFKL pomeron to describe small impact parameter (large | t|) pp collisions. Finally, we predict the pp elastic differential cross section at the unprecedented c.m. energy of s = 14.0 TeV at the Large Hadron Collider (LHC). This prediction assumes crucial significance---because of an approved experiment at LHC: TOTal and Elastic Measurement (TOTEM). The TOTEM group plans to measure pp elastic dsigma/dt at 14.0 TeV all the way from momentum transfer |t| = 0 to |t| ? 10 GeV 2. Their measurement will stringently test not only the diffraction and o-exchange descriptions of the original IIFS model, but also the additional valence quark-quark scattering contribution that we find to be dominant for large |t|. Successful quantitative verification of the predicted dsigma/dt will mean that our picture of the nucleon with an outer cloud of qq¯ condensed ground state, an inner core of topological baryonic charge, and a still smaller core of massless valence quarks provides a realistic description of nucleon structure.

Luddy, Richard Joseph

250

MENU'97 covered many stunning successes of chiral symmetry in intermediate energy reactions, especially of processes that involve pions. These successes include coupling constants, scattering lengths, threshold meson production, electric and magnetic polarizabilities of pions and nucleons, peripheral NN scattering, ?, ? and K decay rates and spectra. The ?N data bank at low energy, which in the past was notorious for the inconsistencies of different data sets, is shown to become consistent by deleting a modest number of previously accepted data sub-sets. There is a consensus on a better value for the pion-nucleon coupling constant, which has been a bone of contention earlier, namely, f?NN2/4?=(75.4±0.4)×10-3 in satisfactory agreement with the Goldberger-Treiman relation. The mass-spin/parity distribution of the experimentally established ?N resonances does not support the prediction of the harmonic oscillator type quark model. Some massive ?++ resonances decay by ? emission to the ?+p? final state. In contrast to this the decay of massive N* states to ?-p? in small, less than 5% of ?++??+p?. A new s-wave ? decay has been identified, D33(1700)?P33(1232)+?. There is interesting new threshold data from CELSIUS on np?d? as well as on pp?pp? and np?np?.

Nefkens, B. M. K.

1998-05-01

251

International Nuclear Information System (INIS)

MENU'97 covered many stunning successes of chiral symmetry in intermediate energy reactions, especially of processes that involve pions. These successes include coupling constants, scattering lengths, threshold meson production, electric and magnetic polarizabilities of pions and nucleons, peripheral NN scattering, ?, ? and K decay rates and spectra. The ?N data bank at low energy, which in the past was notorious for the inconsistencies of different data sets, is shown to become consistent by deleting a modest number of previously accepted data sub-sets. There is a consensus on a better value for the pion-nucleon coupling constant, which has been a bone of contention earlier, namely, f?NN2/4?=(75.4±0.4)x10-3 in satisfactory agreement with the Goldberger-Treiman relation. The mass-spin/parity distribution of the experimentally established ?N resonances does not support the prediction of the harmonic oscillator type quark model. Some massive ?++ resonances decay by ? emission to the ?+p? final state. In contrast to this the decay of massive N* states to ?-p? in small, less than 5% of ?++??+p?. A new s-wave ? decay has been identified, D33(1700)?P33(1232)+?. There is interesting new threshold data from CELSIUS on np?d? as well as on pp?pp? and np?np?

252

International Nuclear Information System (INIS)

The authors give a review about the study of nucleon-nucleon interactions. After a description of the parametrization on NN scattering some potentials are described, which are based on meson exchanges. Then the quarte model of muclear forces is considered. Thereafter nuclear effective interactions are discussed. Finally the Fermi liquid theory of nuclear matter and finite nuclei is introduced. (HSI)

253

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, M. H. S.; Chudakov, E.; Clasie, B.; Connell, S. H.; Dalton, M. M.; Daniel, A.; Day, D. B.; Dutta, D.

2011-01-01

254

Photon structure functions at small $x$ in holographic QCD

We investigate the photon structure functions at small Bjorken variable $x$ in the framework of the holographic QCD, assuming dominance of the Pomeron exchange. The quasi-real photon structure functions are expressed as convolution of the Brower-Polchinski-Strassler-Tan (BPST) Pomeron kernel and the known wave functions of the U(1) vector field in the five-dimensional AdS space, in which the involved parameters in the BPST kernel have been fixed in previous studies of the nucleon structure functions. The predicted photon structure functions, as confronted with data, provide a clean test of the BPST kernel. The agreement between theoretical predictions and data is demonstrated, which supports applications of holographic QCD to hadronic processes in the nonperturbative region. Our results are also consistent with those derived from the parton distribution functions of the photon proposed by Gl\\"uck, Reya, and Schienbein, implying realization of the vector meson dominance in the present model setup.

Watanabe, Akira

2015-01-01

255

Deuteron Spin Structure Functions at Small Bjorken-x

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate polarized deuteron structure functions at small values of the Bjorken variable, x < 0.1. In this region contributions from the coherent interaction of diffractively excited hadronic states with both nucleons become important. A proper treatment of this process requires an extension of the Glauber-Gribov multiple scattering theory to include spin degrees of freedom. In the kinematic domain of current fixed target experiments we observe that shadowing effects in...

Edelmann, J.; Piller, G.; Weise, W.

1997-01-01

256

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

257

Gauge invariance, Lorentz covariance and canonical quantization in nucleon structure studies

There are different operators of quark and gluon momenta, orbital angular momenta, and gluon spin in the nucleon structure study. The precise meaning of these operators are studied based on gauge invariance, Lorentz covariance and canonical quantization rule. The advantage and disadvantage of different definitions are analyzed. A gauge invariant canonical decomposition of the total momentum and angular momentum into quark and gluon parts is suggested based on the decomposition of the gauge potential into gauge invariant (covariant) physical part and gauge dependent pure gauge part. Challenges to this proposal are answered. \\keywords{Physical and pure gauge potentials; Gauge invariant canonical quark and gluon momenta, orbital angular momenta and spins; Homogeneous and non-homogeneous Lorentz transformations; Gauge invariant decomposition and gauge invariant extension; Classical and quantum measurements.

Wang, Fan; Sun, W M; Zhang, P M; Wong, C W

2014-01-01

258

New insights into antikaon-nucleon scattering and the structure of the Lambda(1405)

We perform a combined analysis of antikaon-nucleon scattering cross sections and the recent SIDDHARTA kaonic hydrogen data in the framework of a coupled-channel Bethe-Salpeter approach at next-to-leading order in the chiral expansion of the effective potential. We find a precise description of the antikaon-proton scattering amplitudes and are able to extract accurate values of the scattering lengths, a0=-1.81^+0.30_-0.28 + i 0.92^+0.29_-0.23 fm, a1=+0.48^+0.12_-0.11 + i 0.87^+0.26_-0.20 fm. We also discuss the two-pole structure of the Lambda(1405).

Mai, Maxim

2012-01-01

259

Nucleon Electromagnetic Form Factors

Digital Repository Infrastructure Vision for European Research (DRIVER)

Elastic electromagnetic nucleon form factors have long provided vital information about the structure and composition of these most basic elements of nuclear physics. The form factors are a measurable and physical manifestation of the nature of the nucleons' constituents and the dynamics that binds them together. Accurate form factor data obtained in recent years using modern experimental facilities has spurred a significant reevaluation of the nucleon and pictures of its st...

Jager, Kees

2000-01-01

260

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.

Glöckle W.

2010-04-01

261

International Nuclear Information System (INIS)

The longitudinal charge function in the quasi-elastic peak region is calculated, including effects of two-nucleon collisions. The coupled RPA equation for 2p2h states is solved, using a Thomas-Fermi type theory. To calculate the response function for RPA orders, the Gogny force (a density dependent finite range force) is used, both for the mean field and the residual ph interaction. To include the 2p2h states it was necessary to study the dynamic nuclear mass operator M in the 2p1h (2h1p) approximation. The Gogny force was used as interaction at the vertex of the mass operator. The density dependence of the Gogny force gives a pronounced surface peak in the imaginary part of M. The inclusion of the mass operator in the ph motion gives 2p2h states. Their influence considerably reduces the RPA order response and generally produces a better agreement between theory and experiment, although inexplicable exceptions remain. The investigation suggests that it is not necessary to modify the nuclear form factor

262

Operator analysis of nucleon decay

International Nuclear Information System (INIS)

The operator structure of the effective Hamiltonian mediating nucleon decay is analyzed. Selection rules diagnostic of the underlying superunified theories are derived. A kinship hypothesis important in analyzing nucleon decay is formulated and tests of it are proposed

263

The Generalized Gerasimov-Drell-Hearn Integral and the Spin Structure of the Nucleon

Digital Repository Infrastructure Vision for European Research (DRIVER)

The spin structure functions g1 and g2 have been calculated in the resonance region and for small and intermediate momentum transfer. The calculation is based on a gauge-invariant and unitary model for one-pion photo- and electroproduction. The predictions of the model agree with the asymmetries and the spin sturcture functions recently measured at SLAC, and the first moments of the calculated spin structure functions fullfil the Gerasimov-Drell-Hearn and Burkhardt-Cottingha...

Drechsel, D.; Kamalov, S. S.; Krein, G.; Tiator, L.

1998-01-01

264

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

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

265

Jets in high energy nucleon-nucleon collisions

International Nuclear Information System (INIS)

From the experimental studies of high-energy hardon-nucleon and nucleon-nucleon collisions, by means of nuclear targets applied as detectors, it follows that particles are produced via intermediate objects created first in a 2 ? 2 type endoergic reaction. These objects, called generons, decay in flight into finally observed particles and resonances after their lifetime tausub(g) > or approximately 10-22 s. The jet structure of the outcome in nucleon-nucleon collisions is a simple and indispensable consequence of this particle production mechanism. The picture of the jet structure in the collision outcome observed in the CMS of the colliding nucleons depends on the energy of these nUcleons. New particle production scheme is proposed, which can be tested experimentally; corresponding simple relations between characteristics of colliding nucleons and of produced jets are proposed for a testing

266

International Nuclear Information System (INIS)

The 3He(e, e'p) reaction cross section measuring techniques using vctron accelerator haino. 806 MeV and 643 MeV primary energy at 31 and 28 deg electron scattering is described. Angular distribution for reactions corresponding to 2 and 3 particle forming 3He fission in the 47.5 deg up to 72.5 deg and 54 deg up to 72 deg in the angle of departure range is obtained. Comparison with model and exact calculations is made using various wave functions of 3He ground state and various n-n interaction potentials. In the measured recoil nuclei momentum range with accuracy to +-100 MeV/c the experimental date are best described with the model calculation using Irving wave function or with the exact calculation using Yamaguchi potential and Tabakin parameters. Keeping. Koltun sum rule for these nuclei is examined and its incompatibility just as for some other investigated partially is proved

267

Nuclear effects in the F3 structure function

By using a relativistic framework and accurate nuclear spectral functions we evaluate the ratio F_{3A}/AF_{3N} of deep inelastic neutrino scattering. Parametrizations of this ratio for different values of Q^2 are provided. These results should be useful for taking into account the nuclear effects in analyses of experimental data in neutrino reactions in nuclear targets, and test QCD predictions for the nucleon structure functions. In particular, the size of the nuclear corrections is of the same order of magnitude as the size of the QCD corrections to the Gross-Llewellyn Smith sum rule.

Marco, E; Singh, S K

1998-01-01

268

Nuclear medium modification of the F2 structure function

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

269

Describes how the understanding of structure - property relationships may be used to interpret known compounds and how to design novel molecules and materials with the desired properties. This book covers the theoretical background, experimental techniques and applications of structure-property correlations

Comba, Peter

2010-01-01

270

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

271

Clarifying the Structure of the Nucleon: Status of the SeaQuest Experiment (Fermilab E906)

SeaQuest (Fermilab E906) started commissioning and data collection in March and April of this year. SeaQuest will make a number of measurements in kinematic ranges with a precision that have not been possible in any previous experiment. The experiment uses the Drell-Yan process to probe the light antiquark sea and follows up on measurements of Fermilab E866/NuSea, with a goal of answering important questions raised by that experiment. One is to determine the ratio of the anti-down to anti-up quarks in the nucleon at high Bjorken x. Above x=0.25, NuSea data indicate this ratio could be changing in a surprising manner where the ratio could be dipping below one. This is just one of several determinations SeaQuest will make. A brief description of other physics to be addressed by SeaQuest will be followed by the present status of the experiment as it prepares to start up next spring when the Fermilab MI resumes operation. In the very short commissioning run we were able to validate that the detector and DAQ systems all function. These data are being used to improve the implementation of the analysis chain and guide upgrades of the SeaQuest systems for high intensity running. It is expected that the experiment will be running at full intensity in 2013.

Isenhower, Larry Donald

2012-10-01

272

Bound Nucleon Form Factors, Quark-Hadron Duality, and Nuclear EMC Effect

We discuss the electromagnetic form factors, axial form factors, and structure functions of a bound nucleon in the quark-meson coupling (QMC) model. Free space nucleon form factors are calculated using the improved cloudy bag model (ICBM). After describing finite nuclei and nuclear matter in the quark-based QMC model, we compute the in-medium modification of the bound nucleon form factors in the same framework. Finally, limits on the medium modification of the bound nucleon $F_2$ structure function are obtained using the calculated in-medium electromagnetic form factors and local quark-hadron duality.

Tsushima, K; Melnitchouk, W; Saitô, K; Thomas, A W

2003-01-01

273

Proton structure functions at HERA

The "proton structure" is a wide field. Discussed are predominantly the precision measurements of the proton structure functions at HERA and some of their implications for the LHC measurements. In addition, a discussion of what a proton structure function represents is provided. Finally, a connection to nuclear physics is attempted. This contribution is an updated reprint of a contribution to "Deep Inelastic Scattering 2012".1

Abt, Iris

2014-05-01

274

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.

F Zolfagharpour

2012-03-01

275

Deuteron Spin Structure Functions at Small Bjorken-x

We investigate polarized deuteron structure functions at small values of the Bjorken variable, x < 0.1. In this region contributions from the coherent interaction of diffractively excited hadronic states with both nucleons become important. A proper treatment of this process requires an extension of the Glauber-Gribov multiple scattering theory to include spin degrees of freedom. In the kinematic domain of current fixed target experiments we observe that shadowing effects in g_1^d are approximately a factor 2-3 larger than for the unpolarized structure function F_2^d. Furthermore the tensor structure function b_1 is found to be surprisingly large at x < 0.1 due to coherent double scattering contributions.

Edelmann, J; Weise, W

1998-01-01

276

PROBING THE STANDARD MODEL AND NUCLEON STRUCTURE VIA PARITY VIOLATING ELECTRON SCATTERING

International Nuclear Information System (INIS)

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. Work on two parity-violation experiments is reported in this thesis. They are the Hall A Proton Parity EXperiment (HAPPEX), which ran at Jefferson Laboratory in 1998-1999, and SLAC E-158, which had its first physics running in 2002. HAPPEX measured the parity-violating asymmetry in elastic e-p scattering at a momentum transfer squared of Q2 = 0.477 GeV2 and a scattering angle of 12o. This asymmetry is sensitive to the presence of strange sea quarks in the proton. In particular, it is sensitive to the proton's strange elastic form factors. An asymmetry of ALRep = -15.05 ± 0.98 ± 0.56 ppm was measured, where the first error is statistical and the second error is systematic. Combining this asymmetry measurement with existing measurements of the electromagnetic form factors of the proton and neutron allowed HAPPEX to set new constraints on the strange elastic form factors of the proton GEs + 0.392GMs = 0.025 ± 0.020 ± 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 the electromagnetic form factainty in the electromagnetic form factors. This result is consistent with the absence of a contribution from strange quarks. This thesis reports an analysis of the 1999 data set, with a particular focus on the determination of the raw asymmetry and the corrections to the raw asymmetry to account for helicity-correlated asymmetries in properties of the electron beam

277

Structure functions at large x

Digital Repository Infrastructure Vision for European Research (DRIVER)

Structure function data together with other measurements from fixed-target deep inelastic scattering and hadron-hadron collider experiments which contribute to our knowledge of the parton density functions are reviewed. The inclusive cross-section measurements of neutral and charged current interactions at HERA are presented and their impact on the parton density functions is discussed. Future prospects for an improved knowledge of the parton density functions at large x are...

Zhang, Zhiqing

2001-01-01

278

Truncated Moments of Structure Functions

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a novel new approach to study quark-hadron duality using truncated moments of structure functions, and determine the degree to which individual resonance regions are dominated by leading twist.

Psaker, Ales

2008-01-01

279

The internal structures of the nucleon resonances $N(1875)$ and $N(2120)$

A nucleon resonance with spin-parity $J^P=3/2^-$ and mass about 2.1 GeV is essential to reproduce the photoproduction cross sections for $\\Lambda(1520)$ released by the LEPS and CLAS Collaborations. It can be explained as the third nucleon resonance state $[3/2^-]_3$ in the constituent quark model so that there is no position to settle the $N(1875)$ which is listed in the PDG as the third $N3/2^-$ nucleon resonance. An interpretation is proposed that the $N(1875)$ is from the interaction of a decuplet baryon $\\Sigma(1385)$ and a octet meson $K$, which is favored by a calculation of binding energy and decay pattern in a Bethe-Salpeter approach.

He, Jun

2015-01-01

280

Dynamical rescaling and universality of hadron structure functions

International Nuclear Information System (INIS)

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)

281

Spatial Variation of Nuclear Structure Functions and Heavy Quark Production

Energy Technology Data Exchange (ETDEWEB)

We explore how nuclear modifications to the free nucleon structure functions (also known as shadowing) affect heavy quark production in collisions at different impact parameters. We assume that the nuclear modifications arise from a density dependent effect such as gluon recombination and are thus proportional to the local density. We calculate the dependence of charm and bottom quark production on impact parameter and show that density dependent modifications can lead to significant reductions in the heavy quark production cross sections in central relative to peripheral interactions. {copyright} {ital 1998} {ital The American Physical Society }

Emelyanov, V.; Khodinov, A. [Moscow State Engineering Physics Institute (Technical University), Kashirskoe avenue 31, Moscow, 115409 (Russia); Klein, S.R.; Vogt, R. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Vogt, R. [Physics Department, University of California, Davis, California 95616 (United States)

1998-08-01

282

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

283

A-dependence of weak nuclear structure functions

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

284

Nuclear structure functions in the boundary region of the single-particle kinematics

International Nuclear Information System (INIS)

A theoretical analysis of nuclear functions in the region x?1 is given. It is shown that the contributions of pure nucleons and multiquak components of the nuclear wave function in this region are comparable and the binding effects and Q2-evolution lead to softening of the quark distributions in nucleus. Numerical predictions for the carbon structure function in the cumulative region were made

285

Structured functional principal component analysis.

Motivated by modern observational studies, we introduce a class of functional models that expand nested and crossed designs. These models account for the natural inheritance of the correlation structures from sampling designs in studies where the fundamental unit is a function or image. Inference is based on functional quadratics and their relationship with the underlying covariance structure of the latent processes. A computationally fast and scalable estimation procedure is developed for high-dimensional data. Methods are used in applications including high-frequency accelerometer data for daily activity, pitch linguistic data for phonetic analysis, and EEG data for studying electrical brain activity during sleep. PMID:25327216

Shou, Haochang; Zipunnikov, Vadim; Crainiceanu, Ciprian M; Greven, Sonja

2014-10-18

286

A First Measurement of the Tensor-Polarized Structure Function b1d

International Nuclear Information System (INIS)

The Hermes experiment studies the spin structure of the nucleon using the 27.6 GeV longitudinally polarized positron beam of HERA and an internal target of pure gases. In addition to the well-known spin structure function g1, measured precisely with longitudinally polarized proton and deuteron targets, the use of a tensor-polarized deuteron target provides access to the tensor polarized structure function b1d. The latter, measured with an unpolarized beam, quantifies the dependence of the parton momentum distribution on the nucleon spin. Hermes had a 1-month dedicated run with a tensor polarized deuterium target during the 2000 data taking period. Here preliminary results on the tensor-polarized structure function b1d are presented for the kinematic range 0.002 < x < 0.85 and 0.1 GeV2 < Q2 < 20 GeV2

287

A First Measurement of the Tensor-Polarized Structure Function b1d

The Hermes experiment studies the spin structure of the nucleon using the 27.6 GeV longitudinally polarized positron beam of HERA and an internal target of pure gases. In addition to the well-known spin structure function g_1, measured precisely with longitudinally polarized proton and deuteron targets, the use of a tensor-polarized deuteron target provides access to the tensor polarized structure function b1d. The latter, measured with an unpolarized beam, quantifies the dependence of the parton momentum distribution on the nucleon spin. Hermes had a 1-month dedicated run with a tensor polarized deuterium target during the 2000 data taking period. Here preliminary results on the tensor-polarized structure function b1d are presented for the kinematic range 0.002

Contalbrigo, M

2002-01-01

288

Review of the structure of hadrons from lepton-nucleon interactions

International Nuclear Information System (INIS)

I start with a discussion of the measurements of the ratio of longitudinal to transverse absorption cross sections. The two main parts of my talk then deal with our present knowledge of the parton constituency of the nucleon and a discussion of QCD fits including the separation of higher twist parts. (orig./HSI)

289

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.)

290

Nucleon-nucleon interaction in the chromodielectric soliton model: Dynamics

International Nuclear Information System (INIS)

The present work is an extension of a previous study of the nucleon-nucleon interaction based on the chromodielectric soliton model. The former approach was static, leading to an adiabatic potential. Here we perform a dynamical study in the framework of the generator coordinate method. In practice we derive an approximate Hill-Wheeler differential equation and obtain a local nucleon-nucleon potential as a function of a mean generator coordinate. This coordinate is related to an effective separation distance between the two nucleons by a Fujiwara transformation. This latter relationship is especially useful in studying the quark substructure of light nuclei. We investigate the explicit contribution of the one-gluon exchange part of the six-quark Hamiltonian to the nucleon-nucleon potential, and we find that the dynamics are responsible for a significant part of the short-range N-N repulsion. copyright 1996 The American Physical Society

291

First moment of the flavour octet nucleon parton distribution function using lattice QCD

We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, $\\la x\\ra^{(8)} _{\\mu^2 = 4~\\gev^2 }$. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed in \\cite{Dinter:2012tt}. We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio $\\frac{\\la x \\ra^{(3)}}{\\la x \\ra^{(8)}}$ (with $\\la x \\ra^{(3)}$ the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, $\\frac{\\la x \\ra^{(3)}}{\\la x \\ra^{(8)}} = 0.39(1)(4)$.

Alexandrou, C; Dinter, S; Drach, V; Hadjiyiannakou, K; Jansen, K; Koutsou, G; Vaquero, A

2015-01-01

292

Nucleon electromagnetic form factors

Elastic electromagnetic nucleon form factors have long provided vital information about the structure and composition of these most basic elements of nuclear physics. The form factors are a measurable and physical manifestation of the nature of the nucleons' constituents and the dynamics that binds them together. Accurate form factor data obtained in recent years using modern experimental facilities has spurred a significant reevaluation of the nucleon and pictures of its structure; e.g., the role of quark orbital angular momentum, the scale at which perturbative QCD effects should become evident, the strangeness content, and meson-cloud effects. We provide a succinct survey of the experimental studies and theoretical interpretation of nucleon electromagnetic form factors.

Arrington, J; Zanotti, J M

2006-01-01

293

Nucleon electromagnetic form factors

International Nuclear Information System (INIS)

Elastic electromagnetic nucleon form factors have long provided vital information about the structure and composition of these most basic elements of nuclear physics. The form factors are a measurable and physical manifestation of the nature of the nucleons' constituents and the dynamics that binds them together. Accurate form factor data obtained in recent years using modern experimental facilities has spurred a significant reevaluation of the nucleon and pictures of its structure; e.g., the role of quark orbital angular momentum, the scale at which perturbative QCD effects should become evident, the strangeness content, and meson-cloud effects. We provide a succinct survey of the experimental studies and theoretical interpretation of nucleon electromagnetic form factors

294

Unquenched simulations of four-nucleon interactions

Exploratory simulations of four-nucleon interactions are performed taking into account the dynamical effects of internal nucleon loops. The four-nucleon interactions in the isoscalar and isovector channels are described by Yukawa interactions with auxiliary scalar fields. The nucleon mass and the average field lengths of the scalar fields are determined as a function of nucleon hopping parameter and Yukawa coupling strengths. There are no problems with "exceptional configurations" at strong couplings which make quenched simulations unreliable.

Montvay, Istvan

2012-01-01

295

Unquenched simulations of four-nucleon interactions

International Nuclear Information System (INIS)

Exploratory simulations of four-nucleon interactions are performed taking into account the dynamical effects of internal nucleon loops. The four-nucleon interactions in the isoscalar and isovector channels are described by Yukawa interactions with auxiliary scalar fields. The nucleon mass and the average field lengths of the scalar fields are determined as a function of nucleon hopping parameter and Yukawa coupling strengths. There are no problems with ''exceptional configurations'' at strong couplings which make quenched simulations unreliable.

296

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

297

Longitudinal heavy quark structure function

International Nuclear Information System (INIS)

In this paper we study the heavy-quark contribution to the proton non-singlet structure functions FLNS(x,Q2). In this way we use very recently results for massive operator matrix elements, which contribute to the heavy flavor Wilson coefficients in unpolarized deeply inelastic scattering in the region Q2>>m2. The method of QCD analysis of non-singlet structure function, based on their Jacobi polynomials reconstruction from perturbative QCD predictions for the Mellin moments, is also described

298

Structure functions and parton distributions

International Nuclear Information System (INIS)

The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed

299

Structure functions and parton distributions

Energy Technology Data Exchange (ETDEWEB)

The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.

Martin, A.D.; Stirling, W.J. [Univ. of Durham (United Kingdom); Roberts, R.G. [Rutherford Appleton Lab., Chilton, Didcot (United Kingdom)

1995-07-01

300

Applications of Symmetry Breaking in Determining PDFs of the Nucleon

Energy Technology Data Exchange (ETDEWEB)

Studying the possible breaking of various parton model symmetries by the parton distribution functions of the nucleon can provide important information for the non-perturbative structure of hadrons and the strong interaction. We review theoretical calculations for the breaking of flavor symmetry, quark-antiquark symmetry and charge symmetry in the unpolarized and polarized nucleons using the meson cloud model. We report an estimation for the total distribution of strange and antistrange quarks in the nucleon by combining theoretical calculations of SU(3) flavor symmetry breaking with light antiquark distributions obtained from global analysis of available experimental data.

Cao Fuguang [Institute of Fundamental Sciences, Massey University, Privative Bag 11 222, Palmerston North (New Zealand)

2011-12-14

301

External Momentum, Volume Effects, and the Nucleon Magnetic Moment

Digital Repository Infrastructure Vision for European Research (DRIVER)

We analyze the determination of volume effects for correlation functions that depend on an external momentum. As a specific example, we consider finite volume nucleon current correlators, and focus on the nucleon magnetic moment. Because the multipole decomposition relies on SO(3) rotational invariance, the structure of such finite volume corrections is unrelated to infinite volume multipole form factors. One can deduce volume corrections to the magnetic moment only when a z...

Tiburzi, B. C.

2007-01-01

302

Parity doubling structure of nucleon at non-zero density in the holographic mean field theory

Directory of Open Access Journals (Sweden)

Full Text Available We summarize our recent work in which we develope the holographic mean field approach to study the dense baryonic matter in a bottom-up holographic QCD model including baryons and scalar mesons in addition to vector mesons. We first show that, at zero density, the rate of the chiral invariant mass of nucleon is controlled by the ratio of the infrared boundary values of two baryon fields included in the model. Then, at non-zero density, we find that the chiral condensate decreases with the increasing density indicating the partial restoration of the chiral symmetry. Our result shows that the more amount of the proton mass comes from the chiral symmetry breaking, the faster the effective nucleon mass decrease with density.

He Bing-Ran

2014-06-01

303

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

304

International Nuclear Information System (INIS)

Deep recent data and phenomenology on low-x structure functions are discussed inelastic scattering. We will be interested primordially in the regions Q2 ? 0 i.e. the transition from ?p to, and x ? 10-4 - 10-6 i.e. the region of high parton densities

305

?N: determination of structure functions

International Nuclear Information System (INIS)

Since the 1980 conference a large number of results on structure functions have been reported from neutrino experiments. New data are available from ? and anti ? scattering on protons and neutrons. Measurements of the cross section ratios sigmasup(?n)/sigmasup(?p) as function of energy and scaling variables x and y allow the extraction of differences between the u- and d-quark momentum distributions. Final results on structure functions from ? experiments on isoscalar targets exhibit clearly scaling violations. QCD fits to the data yield values of the scale breaking parameter ? = 0.1-0.2 GeV. From a new measurement of the Q2 evolution of the antiquarks together with F2 data the gluon x distribution has been extracted. The discrepancies in the measurement of the total cross section are still unresolved. (orig.)

306

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Athar, M. Sajjad; Simo?, I. Ruiz; Singh, S. K.; Vacas, M. J. Vicente

2009-01-01

307

Deuteron spin structure functions in the resonance and deep inelastic scattering regions

Energy Technology Data Exchange (ETDEWEB)

We derive relations between spin-dependent nuclear and nucleon g1 and g2 structure functions within the nuclear impulse approximation, which are 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.A. Kulagin; W. Melnitchouk

2008-01-01

308

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

309

Hard probes of short-range nucleon-nucleon correlations

International Nuclear Information System (INIS)

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.

310

Polarized proton structure function in NLO approximation by using Bernstein polynomials

International Nuclear Information System (INIS)

A next-to-leading order QCD analysis of proton structure in polarized deep inelastic lepton-nucleon scattering is present within the framework of the valon model. In this work, we calculated polarized valon distribution in NLO. The Bernstein polynomial method is used to compare QCD prediction to the g1? of available experimental data and direct fits for unknown parameters in the polarized valon distributions at the NLO approximation were performed. Using the obtained results of unpolarized proton structure function in next-to-leading, we computed here the ratio of structure function g1? / F1? as a function of ?. This ratio is very good in agreement with experimental data

311

How does nuclear Fermi motion modify the gluon structure function and J/?-leptoproduction

International Nuclear Information System (INIS)

The effect of the nuclear Fermi motion on the gluon structure function is calculated. Due to the steep decrease of G(x) with x in the nucleon, the ratio GA(x)/G(x) shows a steep rise already at small values of x?0.5. The consequences of such a modified structure function on the e(?)+A ? e(?)+J/?+X reaction are estimated at large and small lepton energies (E=280 GeV and E=30 GeV). Other effects which may modify the gluon structure function in the nucleus are discussed. (author) 13 refs.; 3 figs

312

Color transparency of nuclear matter to hard-scattered hadrons and the nucleon spectral functions

International Nuclear Information System (INIS)

The cross sections for fixed wide angle exclusive interactions have been known to scale. Namely, the energy dependence of the cross sections can be obtained simply by counting the total number of valence quarks in the initial and the final state particles. The model of S. Brodsky and G. Farrar predicts this scaling behavior by assuming that the scattering hadrons shrink to anomalously small configurations at the point of interaction, while that of V. Landshoff accounts for the scaling by assuming that the interaction goes through large distance, independent constituent collisions. One way of differentiating between the two models is by measuring hadron nucleon scattering cross sections off nuclear targets: if the hadrons are indeed small, as assumed by the small hadron model, there must be some time interval before and after the interaction in which the hadrons remain small. During this period the color fields surrounding the hadrons should be weaker than those in the interior of a normal hadron. Thus, the interactions between these hadrons and the medium should be weaker. This means that the quasi elastic scattering cross section between a hadron and a proton from the nucleus at high momentum transfer should be higher than what has been observed at low energies, and should increase with energy. To test these hypotheses, an experimental program was carried out at Brookhaven National Laboratory, Long Island, New York, in which pp and ?p quasi elastic scattering cross pp and ?p quasi elastic scattering cross sections off lithium, carbon, aluminum, copper and lead, and off hydrogen were observed simultaneously at beam energies of 6 and 10 Gev

313

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.

Grasiely F. Borges

2012-06-01

314

Phenomenology of nonperturbative charm in the nucleon

We perform a comprehensive analysis of the role of nonperturbative (or intrinsic) charm in the nucleon, generated through Fock state expansions of the nucleon wave function involving five-quark virtual states represented by charmed mesons and baryons. We consider contributions from a variety of charmed meson-baryon states and find surprisingly dominant effects from the (Dbar^{*0} Lambda_c+) configuration. Particular attention is paid to the existence and persistence of high-x structure for intrinsic charm, and the x dependence of the c-cbar asymmetry predicted in meson-baryon models. We discuss how studies of charmed baryons and mesons in hadronic reactions can be used to constrain models, and outline future measurements that could further illuminate the intrinsic charm component of the nucleon.

Hobbs, T J; Melnitchouk, W

2013-01-01

315

Number of nucleon-nucleon collisions vs. energy in modified Glauber calculations

International Nuclear Information System (INIS)

We modified the standard Glauber model calculations of number of participants (Nw), number of collisions (Ncoll) and their dispertions using a simplified estimate of the energy loss in nucleon-nucleon collision. A fraction equal to 1-k of the initial nucleon momentum is allowed to be lost in each inelastic interaction, so that two 'nucleon-like structures', emerging after the nucleon-nucleon inelastic process, have lower momenta. Therefore, further 'nucleonnucleon' inelastic collisions take place at a lower energy sqrts and with the experimentally known cross-section (?inelpp(sqrts). We obtain a considerable reduction in the number of collisions Ncoll and in the total mean number of charged particles Nch, compared to the standard Glauber approach, while the number of participants Nw is practically unchanged. The model incorporates the experimental values of the average charged particle multiplicity for pp and p p-bar collisions as a function of sqrts, so that the total mean number of charged particles (Nch) could be calculated and compared with the heavy-ion collision data. This model has been used to describe the available data on the average multiplicity obtained for PbPb and AuAu collisions from AGS to RHIC energies. Possible applications of this model to the pA and dA multiplicity data analysis are also discussed

316

Number of nucleon-nucleon collisions vs. energy in modified Glauber calculations

Energy Technology Data Exchange (ETDEWEB)

We modified the standard Glauber model calculations of number of participants (N{sub w}), number of collisions (N{sub coll}) and their dispertions using a simplified estimate of the energy loss in nucleon-nucleon collision. A fraction equal to 1-k of the initial nucleon momentum is allowed to be lost in each inelastic interaction, so that two 'nucleon-like structures', emerging after the nucleon-nucleon inelastic process, have lower momenta. Therefore, further 'nucleonnucleon' inelastic collisions take place at a lower energy sqrts and with the experimentally known cross-section ({sigma}{sub inel}{sup pp}(sqrts). We obtain a considerable reduction in the number of collisions N{sub coll} and in the total mean number of charged particles N{sub ch}, compared to the standard Glauber approach, while the number of participants N{sub w} is practically unchanged. The model incorporates the experimental values of the average charged particle multiplicity for pp and p p-bar collisions as a function of sqrts, so that the total mean number of charged particles (N{sub ch}) could be calculated and compared with the heavy-ion collision data. This model has been used to describe the available data on the average multiplicity obtained for PbPb and AuAu collisions from AGS to RHIC energies. Possible applications of this model to the pA and dA multiplicity data analysis are also discussed.

Feofilov, Grigori; Ivanov, Andrey [St.Petersburg State University, Ulyanovskaya str., 1, St.Petersburg, 198504 (Russian Federation)

2005-01-01

317

Cell Structure and Function Lessons

This overview presents key concepts that students often do not learn from standard textbook presentations and suggests a sequence of learning activities to help students understand how the parts of a cell work together to accomplish the multiple functions of a dynamic living cell. Suggested activities also reinforce student understanding of the relationships between molecules, organelles and cells, the diversity of cell structure and function, and the importance and limitations of diffusion. This overview provides links to Web resources, hands-on activities and discussion activities.

Ingrid Waldron

318

Measurement of the spin-dependent structure functions of the proton and neutron at HERA

International Nuclear Information System (INIS)

HERMES is an experiment under preparation by an international collaboration of physicists from the United States, Germany, Canada, Italy and the Soviet Union to measure the deep inelastic spin-dependent structure functions of the nucleon at DESY, Hamburg, Germany. The structure functions of the proton and neutron will be determined by a completely new technique using polarized internal gas targets of hydrogen, deuterium, and 3He and the longitudinally polarized 35 GeV electron beam of the HERA electron storage ring. Measurement of the deep inelastic spin-structure of both isospin states of the nucleon at the same kinematics and using the same apparatus will provide a high precision test of the Bjorken sum rule

319

Functional nanometer-scale structures

Nanometer-scale structures have properties that are fundamentally different from their bulk counterparts. Much research effort has been devoted in the past decades to explore new fabrication techniques, model the physical properties of these structures, and construct functional devices. The ability to manipulate and control the structure of matter at the nanoscale has made many new classes of materials available for the study of fundamental physical processes and potential applications. The interplay between fabrication techniques and physical understanding of the nanostructures and processes has revolutionized the physical and material sciences, providing far superior properties in materials for novel applications that benefit society. This thesis consists of two major aspects of my graduate research in nano-scale materials. In the first part (Chapters 3--6), a comprehensive study on the nanostructures based on electrospinning and thermal treatment is presented. Electrospinning is a well-established method for producing high-aspect-ratio fibrous structures, with fiber diameter ranging from 1 nm--1 microm. A polymeric solution is typically used as a precursor in electrospinning. In our study, the functionality of the nanostructure relies on both the nanostructure and material constituents. Metallic ions containing precursors were added to the polymeric precursor following a sol-gel process to prepare the solution suitable for electrospinning. A typical electrospinning process produces as-spun fibers containing both polymer and metallic salt precursors. Subsequent thermal treatments of the as-spun fibers were carried out in various conditions to produce desired structures. In most cases, polymer in the solution and the as-spun fibers acted as a backbone for the structure formation during the subsequent heat treatment, and were thermally removed in the final stage. Polymers were also designed to react with the metallic ion precursors during heat treatment in some cases, which led to desired chemical phase formation. The residue of polymer thermal decomposition was also controlled and utilized for certain functionality in some nanostructures. Throughout this study, we successfully fabricated several novel functional structures and revealed a new formation mechanism of metal/metal oxide nanotubes. The magnetic and electrical properties of these nanostructures were studied and optimized for applications in soft magnetic materials and spintronics devices. In the second part, (Chapter 7) a study on memristive switching devices with magnetron-sputtered metal-semiconductor-metal thin film structures based on ZnO is presented. Resistive random access memory (RRAM) is a new, non-volatile memory based on the memristor effect theoretically predicted by Leon Chua in 1971 and first experimentally demonstrated by Hewlett Packard in 2008. The unit cell of a RRAM (a memristor) is a two-terminal device in which the switching medium is sandwiched between the top and bottom electrodes and the resistance of the switching medium can be modulated by applying an electrical signal (current or voltage) to the electrodes. On the other hand, the significance of a memristor, as the fourth element of circuit elements besides resistor, capacitor and inductor, is not limited to just being a candidate for next-generation memory. Owing to the unique i-v characteristics of non-linear memristors that cannot be duplicated with any combinations of the other three basic elements in a passive circuitry, many new electrical functions are being developed based on the memristors. In our study, various contact electrode combinations and semiconductor doping profiles were utilized to achieve different functional resistive switching behaviors and to help fundamentally understand the underlying switching mechanisms in ZnO-based thin film structures. Two distinctive switching mechanisms (ferroelectric charge-induced resistive switching and dopant-induced filament-type resistive switching) have been identified in specified structures. Among them, the ferroelectric charg

Chan, Tsz On Mario

320

Structure function tests of QCD

International Nuclear Information System (INIS)

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)

321

Coupled channels Marchenko inversion for nucleon-nucleon potentials

International Nuclear Information System (INIS)

Marchenko inversion is used to determine local energy independent but channel dependent potential matrices from optimum sets of experimental phase shifts. 3SD1 and 3PF2 channels of nucleon-nucleon systems contain in their off-diagonal potential matrices explicitly the tensor force for T = 0 and 1 isospin. We obtain, together with single channels, complete sets of quantitative nucleon-nucleon potential results which are ready for application in nuclear structure and reaction analyses. The historic coupled channels inversion result of Newton and Fulton is revisited. (orig.)

322

pp Elastic Scattering in Near Forward Direction at LHC and Nucleon Structure

We predict pp elastic differential cross section at LHC at the c.m. energy 14 TeV and momentum transfer range |t| = 0-10 GeV*2, which is planned to be measured by the TOTEM group. The field theory model underlying our phenomenological investigation describes the nucleon as a composite object with an outer cloud of quark-antiquark condensate, an inner core of topological baryonic charge, and a still smaller quark-bag of valence quarks. The model satisfactorily describes the asymptotic behavior of sigma-total(s) and rho(s) as well as the measured antiproton-proton elastic differential cross section at c.m. energies 546 GeV, 630 GeV, and 1.8 TeV. The large |t| elastic amplitude of the model incorporates the QCD hard pomeron (BFKL Pomeron plus next to leading order approximations), the perturbative dimensional counting behavior, and the confinement of valence quarks in a small region within the nucleon. Our predicted pp elastic differential cross section at LHC is compared with those of Bourrely et al. and Desgro...

Islam, M M; Prokudin, A V

2005-01-01

323

Energy Technology Data Exchange (ETDEWEB)

The soft-rotator model (SRM) and a coupled-channels method based on the coupling scheme built on the wave functions of the SRM were applied for a consistent analysis of the nuclear level structure, B(E2) and the nucleon interaction data of {sup 56}Fe. The model could describe the experimental collective levels of {sup 56}Fe up to the excitation energy of 5.5 MeV successfully. Relativistic kinematics and global optical potential form, consistent with nuclear matter theory and Dirac phenomenology, were used in coupled-channels optical model approach to overcome problems left in our previous work. The available nucleon interaction experimental data up to 160 MeV and B(E2) {gamma}-transitions were described satisfactorily. (author)

Sukhovitskii, Efrem Sh. [Radiation Physics and Chemistry Problems Institute, Minsk-Sosny (Belarus); Chiba, Satoshi; Maruyama, Toshiki; Iwamoto, Osamu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Lee, Jeong-Yeon; Lee, Young-Ouk; Chang, Jonghwa [Korea Atomic Energy Research Institute, Daejeon (Korea)

2002-08-01

324

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, determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule

325

International Nuclear Information System (INIS)

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

326

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

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

327

Approximate ways to treat the nucleon-nucleon tensor force in the four-nucleon bound state

International Nuclear Information System (INIS)

Several approximation methods are tested in the four-nucleon bound-state problem as a means to understand how the two-nucleon tensor force propagates through the underlying (2)+(2) and (3)+1 subsystem amplitudes to yield a final four-nucleon binding energy. The aim is to show how to include as much of the nucleon-nucleon tensor force as possible in the dominant S-state component of the four-nucleon wave function for the purpose of optimizing the starting point in the iterative solution of the full problem

328

Nucleon knockout: reaction mechanisms

International Nuclear Information System (INIS)

The treatment of the reactions mechanisms involved in nucleon knockout concerns the ideas of what actually happens in nucleon knockout, whether the deviations from the simplest plane wave picture interfere with an extraction of the wave function, and whether or not the desire to measure the bound state wave functions blinds one to the possibility of obtaining other interesting information from this reaction or from finding exciting new processes taking place. Included are the plane- and distorted-wave impulse approximations, some failures, and more sophisticated reaction mechanisms. 12C(P,2P) and 4He(P,2P) are discussed covering cross sections and spectroscopic factors

329

International Nuclear Information System (INIS)

The experimental techniques related to NN resonance measurements are described. The technique used is the good geometry transmission experiment. The basic idea is to measure the difference in the attenuation factor for the corresponding difference between the total cross sections of N + N interactions for forward and reverse momentum as a function of the solenoid current. 26 references

330

Nucleon - Nucleon Interactions at Short Distances

Despite the progress made in understanding the NN interactions at long distances based on effective field theories, the understanding of the dynamics of short range NN interactions remains as elusive as ever. One of the most fascinating properties of short range interaction is its repulsive nature which is responsible for the stability of strongly interacting matter. The relevant distances, $\\le 0.5$ fm, in this case are such that one expects the onset of quark-gluon degrees of freedom with interaction being dominated by QCD dynamics. We review the current status of the understanding of the QCD dynamics of NN interactions at short distances, highlight outstanding questions and outline the theoretical foundation of QCD description of hard NN processes. We present examples of how the study of the hard elastic NN interaction can reveal the symmetry structure of valence quark component of the nucleon wave function and how the onset of pQCD regime is correlated with the onset of color transparency phenomena in har...

Sargsian, Misak M

2014-01-01

331

Sensitivity to properties of the phi-meson in the nucleon structure in the chiral soliton model

International Nuclear Information System (INIS)

The influence of the ?-meson on the nucleon properties in the chiral soliton model is discussed. Properties of the ?-meson and its photo- and electroproduction are of fundamental interest to CEBAF and its possible future extension. The quark model assigns ? an s bar s structure, thus forbidding the radiative decay ???0?. Experimentally it is also found to be suppressed, yielding a branching fraction of 1.3x10-3. However, ???? and ???+?-?0 are not suppressed at all. Thus, it is possible to incorporate the widths of these decays into the framework of the chiral soliton model, by making use of a specific model for the compliance with OZI rule. Such a model is for example, the ?-? mixing model. Consequence of this in the context of a chiral soliton model, which builds on the ???a1(f1) meson effective Lagrangian, is the context of this report

332

Collisions of protons with light nuclei shed new light on nucleon structure

The high rates of multi-parton interactions at the LHC can provide a unique opportunity to study the multi-parton structure of the hadron. To this purpose high energy collisions of protons with nuclei are particularly suitable. The rates of multi-parton interactions depend in fact both on the partonic multiplicities and on the distributions of partons in transverse space, which produce different effects on the cross section in pA collisions, as a function of the atomic mass number A. Differently with respect to the case of multi-parton interactions in pp collisions, the possibility of changing the atomic mass number provides thus an additional handle to distinguish the diverse contributions. Some relevant features of double parton interactions in pD collisions have been discussed in a previous paper. In the present paper we show how the effects of double and triple correlation terms of the multi-parton structure can be disentangled, by comparing the rates of multiple parton interactions in collisions of proto...

Treleani, Daniele

2012-01-01

333

Experimental Review of Photon Structure Function Data

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present knowledge of the structure of the photon is presented based on results obtained by measurements of photon structure functions at e+e- collider. Results are presented both for the QED structure of the photon as well as for the hadronic structure, where the data are also compared to recent parametrisations of the hadronic structure function F2gamma(x,Q^2). Prospects of future photon structure function measurements, especially at an International Linear Collider are...

Nisius, Richard

2009-01-01

334

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)

335

Energy Technology Data Exchange (ETDEWEB)

Multiplicities for the semi-inclusive production of each charge state of {pi}{sup {+-}} and K{sup {+-}} mesons in deep-inelastic scattering are presented as a function of the kinematic quantities x, Q{sup 2}, z and P{sub h} {sub perpendicular} {sub to}. The multiplicities were extracted from data collected by the HERMES experiment at the HERA storage ring using 27.6 GeV electron and positron beams on a hydrogen or deuterium gas target. These results for identified hadrons constitute the most precise measurement to date, and will significantly enhance our understanding of the proton structure, as well as the fragmentation process in deep-inelastic scattering. Furthermore, the 3D binning at an unprecedented level of precision provides a handle to help disentangle the transverse momentum structure of both. The high level of precision coupled with an intermediate energy regime requires a careful study of the complex interaction between the experimental systematics, theoretical uncertainties, and the applicability of the factorization theorem within the standard framework of leading-twist collinear QCD. This is illustrated by the extraction of the valence quark ratio d{sub {nu}}/u{sub {nu}} at leading-order in {alpha}{sub s}. These results show a strong z-dependence below z {approx} 0.30, which could be interpreted as evidence for factorization breaking. This evidence weakens somewhat when isospin invariance of the fragmentation functions is assumed to be broken. Additionally, the multiplicities for the semi-inclusive production of {pi}{sup 0} mesons in deep-inelastic scattering are presented as a function of z. These multiplicities were extracted from the same data sample as used for the charged meson results. The neutral pion multiplicity is the same as the average charged pion multiplicity, up to z {approx} 0.70. This is consistent with isospin invariance below z {approx} 0.70. The results at high values of z show strong signs of isospin symmetry breaking.

Jossten, Sylvester Johannes

2013-10-15

336

International Nuclear Information System (INIS)

In the analysis of data from ground-based muon telescopes the nucleon spectrum in the upper atmosphere has to be known better than can be found from existing direct measurements. Therefore an indirect determination of this spectrum has been made. In a test of the reliability of the approach the author has been able to reproduce muon spectra within experimental limits in at least the 0.2-50 GeV/c interval and at 0-600 to the zenith direction, at different atmospheric depths and geomagnetic latitudes. A calculation of the muon pressure coefficient for a standard cube gave - 0.16% mb-1 for high latitudes. In order to get some information on the angular distribution of the nucleons the applicability of the Gross transformation has been reexamined. For that purpose a fundamental study of a three-dimensional cascade has also been made. In a very simplified model it is assumed that the nucleons are isotropically produced in the LS. A linear cascade does not reflect the nucleon transport from one direction to another. Thus an exponential law for the nucleons in the atmosphere will not be obtained. The nucleon spectrum is discussed mainly in terms of the attenuation mean free path Lsub(N): In order to meet the rather stringent condition imposed by the muon spectra as a whole it was necessary to put Lsub(N)=160 gcm-2 in the upper atmosphere. (Auth.)

337

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)

338

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)

339

Nuclear Dependence in Weak Structure Functions and the Determination of Weak Mixing Angle

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have studied nuclear medium effects in the weak structure functions $F^A_2(x)$ and $F^A_3(x)$ and in the extraction of weak mixing angle using Paschos Wolfenstein(PW) relation. We have modified the PW relation for nonisoscalar nuclear target. We have incorporated the medium effects like Pauli blocking, Fermi motion, nuclear binding energy, nucleon correlations, pion $\\&$ rho cloud contributions, and shadowing and antishadowing effects.

Athar, M. Sajjad; Haider, H.; Simo, I. Ruiz; Vacas, M. J. Vicente

2013-01-01

340

International Nuclear Information System (INIS)

MENU close-quote 97 covered many stunning successes of chiral symmetry in intermediate energy reactions, especially of processes that involve pions. These successes include coupling constants, scattering lengths, threshold meson production, electric and magnetic polarizabilities of pions and nucleons, peripheral NN scattering, ?, ? and K decay rates and spectra. The ?N data bank at low energy, which in the past was notorious for the inconsistencies of different data sets, is shown to become consistent by deleting a modest number of previously accepted data sub-sets. There is a consensus on a better value for the pion-nucleon coupling constant, which has been a bone of contention earlier, namely, f?NN2/4?=(75.4±0.4)x10-3 in satisfactory agreement with the Goldberger-Treiman relation. The mass-spin/parity distribution of the experimentally established ?N resonances does not support the prediction of the harmonic oscillator type quark model. Some massive ?++ resonances decay by ? emission to the ?+p? final state. In contrast to this the decay of massive N* states to ?-p? in small, less than 5% of ?++??+p?. A new s-wave ? decay has been identified, D33(1700)?P33(1232)+?. There is interesting new threshold data from CELSIUS on np?d? as well as on pp?pp? and np?np?. copyright 1998 American Institute of Physics

341

Probing the parton content of the nucleon

The parton content of the nucleon is explored within a meson-cloud model developed to derive light-cone wave functions for the physical nucleon. The model is here applied to study electromagnetic form factors, distribution amplitudes and nucleon-to-meson transition distribution amplitudes.

Boffi, S

2009-01-01

342

Production cross sections of dimuons and experimental analysis of hadronic structure functions

International Nuclear Information System (INIS)

Analysis, by spectrometry (spectrometer Lezard NA3), of the particle structure (nucleons, mesons) and determination of a multiplicative factor (nearly 2) for the Drell-Yan cross section. Description of the experimental apparatus, production of dimuons on hydrogen and heavy nuclei (platinum), exploration of the nucleon (by inelastic diffusion of leptons, especially neutrinos, and use of the parton model), utilization of the Drell-Yan mechanism describing the production of a continuous spectrum of muons pairs (with experimental test), study of the effects (and subsequent corrections) of the quantum chromodynamics on the amplitude of the strong coupling and on the evolution of the hadronic structure observed as a function of the sensor energy, and at last, after presenting how data are processed analysis of the hadronic structure appearing during the pair production of muons of great masses (4.2< M??<8,5 GeV)

343

The Theory of the Nucleon Spin

I discuss two topics of current interest in the study of the spin structure of the nucleon. First, I discuss whether there is a sum rule for the components of the nucleon's angular moments. Second, I discuss the measurement of the nucleon's transversity distribution in light of recent results reported by the HERMES collaboration at DESY.

Jaffe, R L

2001-01-01

344

Next-to-leading-order constituent quark structure and hadronic structure functions

International Nuclear Information System (INIS)

We utilize the existing next-to-leading-order (NLO) formalism to calculate the partonic structure of a constituent quark. The structure of any hadron can be obtained thereafter using a convolution method. Such a procedure is used to generate the structure functions of protons and pions in NLO, neglecting certain corrections to ?QCD. It is shown that while the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contribution coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the SU(2) symmetry breaking of the nucleon sea and the observed violation of the Gottfried sum rule. These effects are calculated. We obtained an excellent agreement with the experimental data in a wide range of x=[10-6,1] and Q2=[0.5,5000] GeV2 for the proton structure function. We have also calculated pion structure and compared it with the existing data. Again, the model calculations agree rather well with the data from experiment

345

Measuring spin-dependent structure functions at CEBAF

Energy Technology Data Exchange (ETDEWEB)

The author analyses whether CEBAF with a 10 GeV beam could contribute significantly to the understanding of spin-dependent deep-inelastic scattering as well as semi-inclusive reactions. The main advantage of CEBAF is the much better attainable statistics, its great disadvantage its comparably low energy, which limits the accessible x-range to about 0.15 to 0.7. Within these constraints CEBAF could provide (1) high precision data which would be very valuable to understand the Q{sup 2} dependence of the spin-dependent structure functions g{sub 1}(x) and G{sub 2}(x) and (2) the by far most precise determination of the third moments of g{sub 1}(x) and g{sub 2}(x) the latter of which the author argues to be related to a fundamental property of the nucleon.

Schaefer, A. [Universitaet Frankfurt (Germany)

1994-04-01

346

International Nuclear Information System (INIS)

The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis

347

International Nuclear Information System (INIS)

Some of the history behind the form of the wavefunctions of the nucleon and the delta in models of hadron structure is briefly reviewed. The possibility of D-state admixture and its magnitude is analyzed. Moreover the dynamical origin of such admixture and its observable consequences are investigated. Finally comments are given about some recent data analysis. 19 refs.; 1 table

348

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

349

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

International Nuclear Information System (INIS)

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

350

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

351

Isospin dependence of nucleon correlations in ground-state nuclei

Energy Technology Data Exchange (ETDEWEB)

The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. Such predictions can be investigated by performing experiments with exotic beams. The predicted neutron properties for the double closed-shell {sup 132}Sn nucleus exhibit similar correlations as those in {sup 208}Pb. Future relevance of these studies for understanding the properties of all nucleons, including those with high momentum, and the role of three-body forces in nuclei are briefly discussed. Such an implementation will require a proper treatment of the non-locality of the imaginary part of the potentials and a description of high-momentum nucleons as experimentally constrained by the (e, e' p) reactions performed at Jefferson Lab. (orig.)

Charity, R.J. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Dickhoff, W.H. [Washington University, Department of Physics, St. Louis, Missouri (United States); Sobotka, L.G. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Washington University, Department of Physics, St. Louis, Missouri (United States); Waldecker, S.J. [University of Tennessee, Department of Physics, Chattanooga, Tennessee (United States)

2014-02-15

352

SPIN-DEPENDENT NUCLEAR STRUCTURE FUNCTIONS: GENERAL APPROACH WITH APPLICATION TO THE DEUTERON

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study deep-inelastic scattering from polarized nuclei within a covariant framework. A clear connection is established between relativistic and non-relativistic limits, which enables a rigorous derivation of convolution formulae for the spin-dependent nuclear structure functions g_1^A and g_2^A in terms of off-mass-shell extrapolations of polarized nucleon structure functions, g_1^N and g_2^N. Approximate expressions for g_{1,2}^A are obtained by expanding the off-shell g_...

Kulagin, S. A.; Melnitchouk, W.; Piller, G.; Weise, W.

1995-01-01

353

The Jefferson Lab 12 GeV program on nucleon structure

Energy Technology Data Exchange (ETDEWEB)

This slide-show presents the experiments planned at JLab with their 12 GeV upgrade. Experiments reported address: the use of hadron spectra as probes of QCD; the transverse structure of hadrons; the longitudinal structure of hadrons; the 3-dimensional structure of hadrons; hadrons and cold nuclear matter; and low-energy tests of the Standard Model and fundamental symmetries.

Burkert, Volker D. [JLAB

2013-10-01

354

Symmetry relations in nucleon decay

International Nuclear Information System (INIS)

Some experimental consequences of the structure of the effective hamiltonian for nucleon decay are presented. New results concern relations among inclusive decay rates, a striking test of the kinship hypothesis involving ?+ polarization, and soft ? theorems. (orig.)

355

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

356

QCD expectations for the spin structure function $g_1$ in the low $x$ region

The structure function $g_1(x,Q^2)$ is analysed within the formalism based on unintegrated spin dependent parton distributions incorporating the LO Altarelli-Parisi evolution and the double $ln^2(1/x)$ resummation at low $x$. We quantitatively examine possible role of the latter for the small $x$ behaviour of the structure functions $g_1$ of the nucleon within the region which may be relevant for the possible polarized HERA measurements. We show that while the non-singlet structure function is dominated at low $x$ by ladder diagrams the contribution of the non-ladder bremsstrahlung terms is important for the singlet structure function. Predictions for the polarized gluon distribution $\\Delta G(x,Q^2)$ at low $x$ are also given.

Kwiecinski, J

1999-01-01

357

Unquenched simulations of four-nucleon interactions

Energy Technology Data Exchange (ETDEWEB)

Exploratory simulations of four-nucleon interactions are performed taking into account the dynamical effects of internal nucleon loops. The four-nucleon interactions in the isoscalar and isovector channels are described by Yukawa interactions with auxiliary scalar fields. The nucleon mass and the average field lengths of the scalar fields are determined as a function of nucleon hopping parameter and Yukawa coupling strengths. There are no problems with ''exceptional configurations'' at strong couplings which make quenched simulations unreliable.

Montvay, I.

2012-10-15

358

International Nuclear Information System (INIS)

Enormous technical and economic benefits have been conferred on the industry in many countries by the application of nucleonic gauging. The last few years have witnessed many important advances in the field. Basically radioisotope instruments are used to measure a variety of physical properties of material in solid, liquid and gaseous state and many of them are designed to work in the industrial plants and fields under rigorous conditions

359

Dans ce mémoire est présentée l'analyse, dans le but de l'extraction des fonctions de structure, d'une partie des données de diffusion profondément inélastique de muons sur cibles fixes d'hydrogène et de detérium obtenues dans l'expérience NMC (New Muon Collaboration) du CERN. Les fonctions de structure, à partir desquelles s'exprime la probabilité de diffusion à un certain angle et une certaine énergie, contiennent de l'information sur la structure interne du nucléon, plus précisément sur la distribution en énergie des quarks à l'intérieur de celui-ci. L'étude de la variation des fonctions de structure avec le degré d'inélasticité de la diffusion permet de tester la validité de la chromodynamique quantique, la théorie de jauge des interactions fortes

Granier, Thierry

360

Fifth structure function measurements at bates

International Nuclear Information System (INIS)

The unprecedented availability of a polarized electron beam and out-of-plane detection allowed the observation of a novel structure function, the so-called fifth structure function, which corresponds to the imaginary part of the transverse-longitudinal interference response. The first two measurements of this structure function using the 12C(e-vector, e'p) and 2H(e-vector, e'p) reactions inaugurate the Bates out-of-plane program and demonstrate its potential. (author)

361

Sensitivity to properties of the phi-meson in the nucleon structure in the chiral soliton model

Energy Technology Data Exchange (ETDEWEB)

The influence of the {phi}-meson on the nucleon properties in the chiral soliton model is discussed. Properties of the {phi}-meson and its photo- and electroproduction are of fundamental interest to CEBAF and its possible future extension. The quark model assigns {phi} an s{bar s} structure, thus forbidding the radiative decay {phi}{yields}{pi}{sup 0}{gamma}. Experimentally it is also found to be suppressed, yielding a branching fraction of 1.3{times}10{sup {minus}3}. However, {phi}{yields}{rho}{pi} and {phi}{yields}{pi}{sup +}{pi}{sup {minus}}{pi}{sup 0} are not suppressed at all. Thus, it is possible to incorporate the widths of these decays into the framework of the chiral soliton model, by making use of a specific model for the compliance with OZI rule. Such a model is for example, the {omega}-{phi} mixing model. Consequence of this in the context of a chiral soliton model, which builds on the {pi}{rho}{omega}a{sub 1}(f{sub 1}) meson effective Lagrangian, is the context of this report.

Mukhopadhyay, N.C.; Zhang, L. [Rensselaer Polytechnic Inst., Troy, NY (United States)

1994-04-01

362

International Nuclear Information System (INIS)

The Bates Large Acceptance Spectrometer Toroid (BLAST) is a detector designed to study the spin-dependent electromagnetic response of few-body nuclei at momentum transfers up to 1 (GeV/c)2 at the MIT/Bates Linear Accelerator Center's South Hall Ring (SHR). The BLAST detector consists of an eight-sector copper coil array producing a toroidal magnetic field, instrumented with two opposing wedge-shaped sectors of wire chambers, scintillation detectors, Cerenkov counters, neutron detectors, a lead-glass forward calorimeter, and recoil detectors. The ability of BLAST to carry out multi-particle detection over a large solid angle from polarized internal targets will provide an unprecedented and unique opportunity to study simultaneously the spin structure of the few-body nuclear ground states, the reaction mechanisms, and the nucleon form factors. Presently, BLAST is under construction and it is on schedule to be done in summer 2001. A status of the project is presented as well as highlights of the scientific program

363

The structure and function of cartilage proteoglycans

Directory of Open Access Journals (Sweden)

Full Text Available Cartilage contains a variety of proteoglycans that are essential for its normal function. These include aggrecan, decorin, biglycan, fibromodulin and lumican. Each proteoglycan serves several functions that are determined by both its core protein and its glycosaminoglycan chains. This review discusses the structure/function relationships of the cartilage proteoglycans, and the manner in which perturbations in proteoglycan structure or abundance can adversely affect tissue function.

P J Roughley

2006-11-01

364

Energy Technology Data Exchange (ETDEWEB)

Recent progress in few-nucleon physics achieved by Italian research groups is described. Results for relativistic effects in elastic three-nucleon form factors (Rome group), hadronic and electromagnetic observables in three- and four-nucleon systems with special emphasis on three-nucleon force effects (Pisa and Trento groups), and spectra of nuclei with more than 4 nucleons (Padua group) are presented.

Leidemann, Winfried, E-mail: leideman@science.unitn.i [Dipartimento di Fisica, Universita di Trento and INFN (Gruppo Collegato di Trento), via Sommarive 14, I-38100 Trento (Italy)

2009-05-01

365

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.

366

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

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

367

The Two-Nucleon System in Three Dimensions

A recently developed formulation for treating two- and three-nucleon bound states in a three-dimensional formulation based on spin-momentum operators is extended to nucleon-nucleon scattering. Here the nucleon-nucleon t-matrix is represented by six spin-momentum operators accompanied by six scalar functions of momentum vectors. We present the formulation and provide numerical examples for the deuteron and nucleon-nucleon scattering observables. A comparison to results from a standard partial wave decomposition establishes the reliability of this new formulation.

Golak, J; Skibinski, R; Witala, H; Rozpedzik, D; Topolnicki, K; Fachruddin, I; Elster, Ch; Nogga, A

2010-01-01

368

Three-Nucleon Forces Revisited - Some Historical Thoughts

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

369

From structure to function, via dynamics

Neurons in the brain are wired into a synaptic network that spans multiple scales, from local circuits within cortical columns to fiber tracts interconnecting distant areas. However, brain function require the dynamic control of inter-circuit interactions on time-scales faster than synaptic changes. In particular, strength and direction of causal influences between neural populations (described by the so-called directed functional connectivity) must be reconfigurable even when the underlying structural connectivity is fixed. Such directed functional influences can be quantified resorting to causal analysis of time-series based on tools like Granger Causality or Transfer Entropy. The ability to quickly reorganize inter-areal interactions is a chief requirement for performance in a changing natural environment. But how can manifold functional networks stem "on demand" from an essentially fixed structure? We explore the hypothesis that the self-organization of neuronal synchronous activity underlies the control of brain functional connectivity. Based on simulated and real recordings of critical neuronal cultures in vitro, as well as on mean-field and spiking network models of interacting brain areas, we have found that "function follows dynamics", rather than structure. Different dynamic states of a same structural network, characterized by different synchronization properties, are indeed associated to different functional digraphs (functional multiplicity). We also highlight the crucial role of dynamics in establishing a structure-to-function link, by showing that whenever different structural topologies lead to similar dynamical states, than the associated functional connectivities are also very similar (structural degeneracy).

Stetter, O.; Soriano, J.; Geisel, T.; Battaglia, D.

2013-01-01

370

Functional Projections and Event Structure.

Previous theory concerning the variable behavior verbs in unaccusative/unergative alternation in Dutch, Hebrew, and Italian, which concludes that the unergative/unaccusative distinction is not syntactic but aspectual/semantic, is challenged. Discrepancies and inconsistencies are found in the grammatical functions of aspectual functional…

Khym, Hangyoo; Kookiattikoon, Supath

1997-01-01

371

Few nucleon problem with realistic nucleon--nucleon interactions

International Nuclear Information System (INIS)

The few-nucleon problem with realistic nucleon-nucleon interactions is briefly reviewed. Consideration is limited to energies below 300 MeV. Specific phenomena discussed include the trinucleon bound state, N-d elastic scattering, N-d breakup reactions, and polarization effects

372

Structure of 13 C and 13 N nuclei in the shell model and nucleon form factors

International Nuclear Information System (INIS)

Results of investigations into 13 C and 13 N wave functions with regard to 2p-shell within the framework of translation-invariant shell model are presented. Expressions are obtained for magnetic moments, lg ft for 13 N ? 13 C ?-decay, longitudinal and transverse formfactors of electron elastic scattering on 13 C nucleus (expressed through transitional densities). A good description of experimental data is obtained, in particular, for the transverse M1-formfactor. 21 refs., 5 figs., 3 tabs

373

Chiral invariant renormalization of the pion-nucleon interaction

International Nuclear Information System (INIS)

The leading divergences of the generating functional for Green functions of quark currents between one-nucleon states are calculated with heat kernel techniques. The results allow for a chiral invariant renormalization of all two-nucleon Green functions of the pion-nucleon system to O(p3) in the low-energy expansion. (author)

374

Functional dynamics. II: Syntactic structure

Functional dynamics, introduced in a previous paper [Physica D 138 (2000) 225-250] is analyzed, focusing on the formation of a hierarchical rule to determine the dynamics of the functional value. To study the periodic (or non-fixed) solution, the functional dynamics is separated into fixed and non-fixed parts. It is shown that the fixed parts generate a one-dimensional map by which the dynamics of the functional values of some other parts are determined. Piecewise linear maps with multiple branches are generally created, while an arbitrary one-dimensional map can be embedded into this functional dynamics if the initial function coincides with the identity function over a finite interval. Next, the dynamics determined by the one-dimensional map can again generate a ‘meta-map’, which determines the dynamics of the generated map. This hierarchy of meta-rules can continue recursively. It is also shown that the dynamics can produce ‘meta-chaos’ with an orbital instability that is stronger than exponential. The relevance of the generated hierarchy to biological and language systems is discussed, in relation with the formation of syntax of a network.

Kataoka, Naoto; Kaneko, Kunihiko

2001-02-01

375

Functional Dynamics; 2, Syntactic Structure

Functional dynamics, introduced in a previous paper, is analyzed, focusing on the formation of a hierarchical rule to determine the dynamics of the functional value. To study the periodic (or non-fixed) solution, the functional dynamics is separated into fixed and non-fixed parts. It is shown that the fixed parts generate a 1-dimensional map by which the dynamics of the functional values of some other parts are determined. Piecewise-linear maps with multiple branches are generally created, while an arbitrary one-dimensional map can be embedded into this functional dynamics if the initial function coincides with the identity function over a finite interval. Next, the dynamics determined by the one-dimensional map can again generate a `meta-map', which determines the dynamics of the generated map. This hierarchy of meta-rules can continue recursively. It is also shown that the dynamics can produce `meta-chaos' with an orbital instability that is stronger than exponential. The relevance of the generated hierarch...

Kataoka, N

1999-01-01

376

Studies of 3D structure of the nucleon with CLAS at Jlab

Energy Technology Data Exchange (ETDEWEB)

Studies of single-spin asymmetries in pions electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized and polarized targets, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility, are presented. A substantial sin phih amplitude has been measured in the the cross section as a function of the azimuthal angle phih of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum has been extracted with significantly higher precision than previous data and is compared to model calculations.

Mher Aghasyan

2011-12-01

377

Studies of 3D structure of the nucleon with CLAS at JLab

Energy Technology Data Exchange (ETDEWEB)

Studies of single-spin asymmetries in pions electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized and polarized targets, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility, are presented. A substantial sin {phi}{sub h} amplitude has been measured in the the cross section as a function of the azimuthal angle {phi}{sub h} of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum has been extracted with significantly higher precision than previous data and is compared to model calculations.

Aghasyan, Mher [INFN, Laboratori Nazionali di Frascati, 00044 Frascati (Italy); Collaboration: CLAS Collaboration

2011-12-14

378

Structure and functional properties of colloidal systems

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

379

Low x physics, deep inelastic scattering and structure functions

International Nuclear Information System (INIS)

HERA experiments together with polarised fixed target lepton-nucleon scattering experiments and hadron-hadron interactions have provided this year a wealth of new results on the structure of the proton and on low x physics where x is the fraction of nucleon momentum carried by the struck quark in lepton a scattering. Measurement o the W charge asymmetry in CDF at FNAL has provided new constraints on the d/u ratio in the proton. The Drell-Yan asymmetry (?pp - ?pn)/(?pp + ?pn) measured by the NA51 experiment at CERN confirms that there are more of anti d than anti u in the proton. New data on proton, deuteron and neutron polarized structure functions from the SLAC E143 and CERN SMC experiments are in good agreement. The naive Ellis-Jaffe sum rule is violated by at least two standard deviations and the Bjorken Sum rule is verified to within about 10%. The measured QCD corrections to the Bjorken Sum Rule using the low Q2 data from E143 provide a new method to determine the QCD running coupling constant ?5. Combining fixed target data from E665 and FNAL and HERA results from H1 and ZEUS, the measurements of the proton structure function F2(x,Q2) cover the very large kinematic range of 0.3 2 4 GeV2 and 2.10-4 2 with x decreasing is observed at x values below 10-1 and up to Q2 values of about 1000 GeV2. The interpretation of the F2 behaviour at low x by the BFKL and GLAP mechanisms is discussed together with possible ''footprints'' of the BFKL dynamics in the hadronic final states of deep inelastic scattering events at HERA. The properties of the deep inelastic scattering events at HERA with no energy in a large gap of rapidity close to the proton direction are reviewed. A signal from rapidity gap events in CDF and DO experiments is presented. (author). 102 refs., 31 figs., 5 tabs

380

Application of Gamov wavefunctions to beta delayed nucleon emission

International Nuclear Information System (INIS)

In the present paper we introduce a simple model to describe the process of beta delayed nucleon emission. A standard shell model calculation can be used to describe the beta decay of the precursor and the single particle structure of the particle unbound levels of the emitter nucleus. The single particle width for nucleon emission is then obtained from the Gamow wave functions of a suitable single particle potential. We compare our theoretical predictions with recent experimental data on beta delayed protons produced in the beta decay of 31Ar. (author)

381

Nucleon-phonon coupling in hot, rapidly rotating nuclei (I)

The particle-vibration coupling formalism is generalized to deal with hot, strongly rotating nuclei. In this way the basis to carry out a microscopic description of the structure of compound nuclei has been developed, in particular the calculation of the effective mass of nucleons close to the Fermi energy. As a consequence, it will be possible to provide a realistic estimate of the nuclear level density as a function of rotational frequency and temperature, a quantity which is among the key ingredients needed in the study of the evolution of the cooling of the compound nucleus through nucleon and gamma-decay.

Donati, P; Shimizu, Y R; Bortignon, P F; Broglia, R A

1999-01-01

382

Do Gluons Carry Half of the Nucleon Momentum?

International Nuclear Information System (INIS)

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.

383

New model for nucleon generalized parton distributions

Energy Technology Data Exchange (ETDEWEB)

We describe a new type of models for nucleon generalized parton distributions (GPDs) H and E. They are heavily based on the fact nucleon GPDs require to use two forms of double distribution (DD) representations. The outcome of the new treatment is that the usual DD+D-term construction should be amended by an extra term, {xi} E{sub +}{sup 1} (x,{xi}) which has the DD structure {alpha}/{beta} e({beta},{alpha}, with e({beta},{alpha}) being the DD that generates GPD E(x,{xi}). We found that this function, unlike the D-term, has support in the whole -1 <= x <= 1 region. Furthermore, it does not vanish at the border points |x|={xi}.

Radyushkin, Anatoly V. [JLAB, Newport News, VA (United States)

2014-01-01

384

Nucleon-Nucleon Interactions from the Quark Model

International Nuclear Information System (INIS)

We report on investigations of the applicability of non-relativistic constituent quark models to the low-energy nucleon-nucleon (NN) interaction. The major innovations of a resulting NN potential are the use of the 3P0 decay model and quark model wave functions to derive nucleon-nucleon-meson form-factors, and the use of a colored spin-spin contact hyperfine interaction to model the repulsive core rather than the phenomenological treatment common in other NN potentials. We present the results of the model for experimental free NN scattering phase shifts, S-wave scattering lengths and effective ranges and deuteron properties. Plans for future study are discussed.

385

Nucleon-Nucleon Interactions from the Quark Model

We report on investigations of the applicability of non-relativistic constituent quark models to the low-energy nucleon-nucleon (NN) interaction. The major innovations of a resulting NN potential are the use of the $^3$P$_0$ decay model and quark model wave functions to derive nucleon-nucleon-meson form-factors, and the use of a colored spin-spin contact hyperfine interaction to model the repulsive core rather than the phenomenological treatment common in other NN potentials. We present the results of the model for experimental free NN scattering phase shifts, S-wave scattering lengths and effective ranges and deuteron properties. Plans for future study are discussed.

Downum, Clark; Barnes, Ted; Swanson, Eric; Vidana, Isaac

2010-01-01

386

Statistical Error analysis of Nucleon-Nucleon phenomenological potentials

Nucleon-Nucleon potentials are commonplace in nuclear physics and are determined from a finite number of experimental data with limited precision sampling the scattering process. We study the statistical assumptions implicit in the standard least squares fitting procedure and apply, along with more conventional tests, a tail sensitive quantile-quantile test as a simple and confident tool to verify the normality of residuals. We show that the fulfilment of normality tests is linked to a judicious and consistent selection of a nucleon-nucleon database. These considerations prove crucial to a proper statistical error analysis and uncertainty propagation. We illustrate these issues by analyzing about 8000 proton-proton and neutron-proton scattering published data. This enables the construction of potentials meeting all statistical requirements necessary for statistical uncertainty estimates in nuclear structure calculations.

Perez, R Navarro; Arriola, E Ruiz

2014-01-01

387

Statistical error analysis for phenomenological nucleon-nucleon potentials

Nucleon-nucleon potentials are common in nuclear physics and are determined from a finite number of experimental data with limited precision sampling the scattering process. We study the statistical assumptions implicit in the standard least-squares ?2 fitting procedure and apply, along with more conventional tests, a tail-sensitive quantile-quantile test as a simple and confident tool to verify the normality of residuals. We show that the fulfillment of normality tests is linked to a judicious and consistent selection of a nucleon-nucleon database. These considerations prove crucial to a proper statistical error analysis and uncertainty propagation. We illustrate these issues by analyzing about 8000 proton-proton and neutron-proton scattering published data. This enables the construction of potentials meeting all statistical requirements necessary for statistical uncertainty estimates in nuclear structure calculations.

Navarro Pérez, R.; Amaro, J. E.; Ruiz Arriola, E.

2014-06-01

388

Bioturbation, ecosystem functioning and community structure

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of community structure on the functioning of the ecosystem is an important issue in ecology due to continuing global species loss. The influence of infaunal community structure on the functioning of marine systems is proposed here to act primarily through bioturbation of the sediment. Nutrient concentration in the water column, generated by release from the sediment, was used as a measure of ecosystem functioning. In situ and laboratory experiments showed a significant diffe...

Biles, C. L.; Paterson, D. M.; Ford, R. B.; Solan, M.; Raffaelli, D. G.

2002-01-01

389

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

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

390

Structural Induction Principles for Functional Programmers

Digital Repository Infrastructure Vision for European Research (DRIVER)

User defined recursive types are a fundamental feature of modern functional programming languages like Haskell, Clean, and the ML family of languages. Properties of programs defined by recursion on the structure of recursive types are generally proved by structural induction on the type. It is well known in the theorem proving community how to generate structural induction principles from data type declarations. These methods deserve to be better know in the functional progr...

Caldwell, James

2013-01-01

391

Krein structures for Wightman and Schwinger functions

International Nuclear Information System (INIS)

For quantum field theories that do not satisfy the Wightman positivity condition, a Hilbert space structure condition is proposed, which guarantees a Krein structure for the space of states associated to the Wightman functions. The analogous problem for the Schwinger function is also discussed, as well as the conditions that ensure the analytic continuation of a Krein structure in the Euclidean case and vice versa. The Gupta--Bleuler formulation of free quantum electrodynamics is discussed as an example

392

Cell Membrane Structure and Function

Students learn about the different structures that comprise cell membranes, fulfilling part of the Research and Revise stages of the legacy cycle. They 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 Lugol's solution.

VU Bioengineering RET Program,

393

Lepton Scattering Cross Section and Nuclear Structure Function of 4He and 12C Nuclei

Directory of Open Access Journals (Sweden)

Full Text Available This paper is an effort to extract the structure function, the EMC ratio, and the lepton scattering cross section in the convolution nuclear theory framework for 4He and 12C nuclei. We suppose that, in conventional approach, based on harmonic oscillator model, one could consider for a nucleus shell different hw parameters which are associated with the square root of the mean radius of the nucleus shells. We use GRV free nucleon structure function, which has good agreement with the proton and neutron structure function, extracted from experimental results. In addition, the lepton scattering cross sections of 4He and 12C nuclei are calculated in energy higher than 1 GeV. The extracted results show good agreement with experimental data.

Mir Hamid Musavi

2013-10-01

394

Spin-dependent nuclear structure functions general approach with application to the deuteron

We study deep-inelastic scattering from polarized nuclei within a covariant framework. A clear connection is established between relativistic and non-relativistic limits, which enables a rigorous derivation of convolution formulae for the spin-dependent nuclear structure functions g_1^A and g_2^A in terms of off-mass-shell extrapolations of polarized nucleon structure functions, g_1^N and g_2^N. Approximate expressions for g_{1,2}^A are obtained by expanding the off-shell g_{1,2}^N about their on-shell limits. As an application of the formalism we consider nuclear effects in the deuteron, knowledge of which is necessary to obtain accurate information on the spin-dependent structure functions of the neutron.

Kulagin, S A; Piller, G; Weise, W; Kulagin, S A; Melnitchouk, W; Piller, G; Weise, W

1994-01-01

395

Spin-dependent nuclear structure functions: General approach with application to the deuteron

International Nuclear Information System (INIS)

We study deep-inelastic scattering from polarized nuclei within a covariant framework. A clear connection is established between relativistic and nonrelativistic limits, which enables a rigorous derivation of convolution formulas for the spin-dependent nuclear structure functions g1A and g2A in terms of off-mass-shell extrapolations of polarized nucleon structure functions, g1N and g2N. Approximate expressions for g1,2A are obtained by expanding the off-shell g1,2N about their on-shell limits. As an application of the formalism we consider nuclear effects in the deuteron, knowledge of which is necessary to obtain accurate information on the spin-dependent structure functions of the neutron

396

International Nuclear Information System (INIS)

In the framework of the Quantum Chromodynamics (QCD), the nucleon is described as being composed of three valence quarks surrounded by a sea of virtual quark-antiquark pairs and gluons. If the role of this virtual sea in the nucleon properties is inferred to be important, this contribution is still poorly understood. In this context, we study the role of the strange quarks in the nucleon since this is the lightest quark flavor of the sea with no valence contribution. We are determining its contribution to the charge and magnetization distributions in the nucleon via parity violation experiments. The measurement is performed by elastically scattering polarized electrons from nucleon target. A world wide program in which the G0 experiment takes place has been performing for a decade. The G0 experiment and the analysis of the results from its forward angles phase are the topics of this thesis. This document presents the physics case of the strangeness content of the nucleon (mass, spin, impulsion). It describes also the formalism related to the electroweak probe and the form factors, and then the principle of parity violating asymmetry measurement. The G0 experimental setup, which was built and installed in the Hall C of the Jefferson Laboratory (Usa), is detailed. This set-up was designed for the measurement of asymmetries of the order of 10-6 with an overall relative uncertainty better than 10 %, over a momentum transfer range 0.1-1 (GeV/c)2. The various steps of the data analysis are exposed. They have allowed us to start from measured counting rates to reach parity violating physics asymmetries. This required a careful treatment of the various sources of systematical errors which is discussed extensively. Finally the results from the G0 forward angle measurement, its comparison with others experiments and with theoretical models, are presented. They support a non null strange quark contribution. (author)

397

Short-Range Nucleon-Nucleon Correlations

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Higinbotham, Douglas W.

2010-01-01

398

Nucleon properties in nuclear medium

International Nuclear Information System (INIS)

The modifications of the nucleon structure due to the presence of an external baryon medium are investigated. To that end the Nambu-Jona-Lasinio model is used to evaluate the pion decay constant and the pion and sigma masses at finite density. Those meson properties serve to fix the parameters of the linear chiral sigma model, which is then solved in a variational projected mean field approach in order to obtain nucleon properties. The proton radius shows an increase of 19% and the nucleon mass a decrease of 17% if the medium reaches nuclear matter density. The magnetic moments and axial vector coupling constant are less modified whereas the pion nucleon coupling constant stays practically constant at increasing medium density. All form factors show remarkable reduction at finite transfer momenta. (author). 20 refs, 8 figs, 1 tab

399

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

400

Unconstrained energy functionals for electronic structure calculations

Energy Technology Data Exchange (ETDEWEB)

The performance of conjugate gradient schemes for minimizing unconstrained energy functionals in the context of electronic structure calculations is studied. The unconstrained functionals allow a straightforward application of conjugate gradients by removing the explicit orthonormality constraints on the quantum-mechanical wave functions. However, the removal of the constraints can lead to slow convergence, in particular when preconditioning is used. The convergence properties of two previously suggested energy functionals are analyzed, and a new functional is proposed, which unifies some of the advantages of the other functionals. A numerical example confirms the analysis.

Pfrommer, B.G.; Demmel, J. [Univ. of California, Berkeley, CA (United States); Simon, H. [Lawrence Berkeley National Lab., CA (United States). National Energy Research Scientific Computing Div.

1998-04-01

401

International Nuclear Information System (INIS)

The experimental technique and the measured results are presented for investigation of the 3He(e, e'p) reaction at the incident electron energies Esup(i)=806 and 643 MeV and the scattering angles thetasub(e)=31 and 28 deg. The energy resolution was 4 and 2.6 MeV, respectively. The angular (thetasub(p)=47.5-72.5 deg and 54-72 deg) and momentum (qsub(R)=+-100 MeV/c) distributions for protons from two- and three-particle desintegrations of 3He are compared with model and exact calculations using various ground state wave functions of the 3He. It is shown that the obtained angular and momentum distributions are described best of all with a model calculation using the Irving wave function and with the exact calculation using the Yamaguchi potential and Tabakin parameters

402

International Nuclear Information System (INIS)

The recently measured inclusive electron-proton cross section in the nucleon resonance region, performed with the CLAS detector at the Thomas Jefferson Laboratory, has provided new data for the nucleon structure function F2 with previously unavailable precision. In this paper we propose a description of these experimental data based on a Regge-dual model for F2. The basic inputs in the model are nonlinear complex Regge trajectories producing both isobar resonances and a smooth background. The model is tested against the experimental data, and the Q2 dependence of the moments is calculated. The fitted model for the structure function (inclusive cross section) is a limiting case of the more general scattering amplitude equally applicable to deeply virtual Compton scattering. The connection between the two is discussed

403

International Nuclear Information System (INIS)

It is possible to measure the deep-inelastic spin-dependent structure functions g1/sup p/(x) and g1/sup n/(x) for the proton and neutron using internal polarized hydrogen, deuterium, and 3He targets of polarization 50% and thickness 1014 to 1015 cm-2 and the 60 mA longitudinally polarized 30 GeV electron beam in the HERA electron storage ring. The measurement of the deep-inelastic spin-structure of both isospin states of the nucleon at the same kinematics and using the same apparatus allows the Bjorken sum rule to be experimentally checked. In addition, it uniquely constrains the spin distribution of the u and d quarks as a function of x in any model of the nucleon. Possible target and detector configurations are described and an estimate of the accuracy of such a measurement is presented

404

Electronic structure tuning of diamondoids through functionalization

We investigated the changes in electronic structures induced by chemical functionalization of the five smallest diamondoids using valence photoelectron spectroscopy. Through the variation of three parameters, namely functional group (thiol, hydroxy, and amino), host cluster size (adamantane, diamantane, triamantane, [121]tetramantane, and [1(2,3)4]pentamantane), and functionalization site (apical and medial) we are able to determine to what degree these affect the electronic structures of the overall systems. We show that unlike, for example, in the case of halobenzenes, the ionization potential does not show a linear dependence on the electronegativity of the functional group. Instead, a linear correlation exists between the HOMO-1 ionization potential and the functional group electronegativity. This is due to localization of the HOMO on the functional group and the HOMO-1 on the diamondoid cage. Density functional theory supports our interpretations.

Rander, Torbjörn; Staiger, Matthias; Richter, Robert; Zimmermann, Tobias; Landt, Lasse; Wolter, David; Dahl, Jeremy E.; Carlson, Robert M. K.; Tkachenko, Boryslav A.; Fokina, Natalie A.; Schreiner, Peter R.; Möller, Thomas; Bostedt, Christoph

2013-01-01

405

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

406

International Nuclear Information System (INIS)

This report outlines the progress made in the past 15 months toward completion of a long-term pion-nucleon partial wave analysis in collaboration with R.E. Cuthosky at Carnegie-Mellon University. The report details other theoretical work done during this time period, including work on the Table of Particle Properties, 1982

407

Measurement of the deuteron elastic structure functions at large momentum transfers

Energy Technology Data Exchange (ETDEWEB)

The cross section for elastic electron-deuteron scattering has been measured using the Hall A Facility of Jefferson Laboratory. Scattered electrons and recoiling deuterons were detected in coincidence in the two 4 GeV/c High Resolution Spectrometers (HRS) of Hall A. The deuteron elastic structure functions A(Q{sup 2}) and B(Q{sup 2}) have been extracted from these data. Results for the measurement of A(Q{sup 2}) in the range of 0.7 ? Q{sup 2} ? 6.0 (GeV/c){sup 2} are reported. Results for the magnetic structure function, B(Q{sup 2}), are presented in the range of 0.7 ? Q{sup 2} ? 1.35 (GeV/c){sup 2}. The results for both structure functions are compared to predictions of meson-nucleon based models, both with and without the inclusion of meson-exchange currents. The A(Q{sup 2}) results are compared to predictions of the dimensional scaling quark model and perturbative quantum chromodynamics. The results can provide insights into the transition from meson-nucleon to quark-gluon descriptions of the nuclear two-body system.

Kathy McCormick

1999-08-01

408

The triton with long-range chiral N3LO three nucleon forces

Long-range contributions to the three-nucleon force that have been recently worked out in chiral effective field theory at next-to-next-to-next-to-leading order are for the first time included in the triton and the doublet nucleon-deuteron scattering length calculations. The strengths of the two short-range terms available at this order in the chiral expansion are determined from the triton binding energy and the neutron-deuteron doublet scattering length. The structure of the resulting three-nucleon force is explored and effects for the two-nucleon correlation function in the triton are investigated. Expectation values of the individual contributions to the three-nucleon force in the triton are found to be in the range from a few 100 keV to about 1 MeV. Our study demonstrates that the very complicated operator structure of the novel chiral three-nucleon forces can be successively implemented in three-nucleon Faddeev calculations.

Skibinski, R; Topolnicki, K; Witala, H; Epelbaum, E; Gloeckle, W; Krebs, H; Nogga, A; Kamada, H

2011-01-01

409

International Nuclear Information System (INIS)

In CTa collisions at 4.2 GeV/c per nucleon we analyze the characteristics of protons with momentum p> or =0.7 GeV/c and certain properties of ?- mesons as functions of the cumulative variable ?0. We observe emission of protons with values of the variable ?0>1, and in the region ?0approx.1 the dependence of the proton characteristics and also the ?--meson accompaniment as a function of ?0 changes qualitatively. The experimental results are compared with the predictions of the cascade model. The model satisfactorily describes the average characteristics of particles accompanying the emission of the cumulative proton, but in the cumulative region ( ?0> or approx. =1) it does not agree with the experimental average characteristics of the protons having the largest value of ?0 in an event

410

Snake Jaws: Connecting Structure and Function

In this lesson designed to enhance literacy skills, students learn how animals' physical characteristics, such as jaw structure, are directly related to the function they perform when the animal interacts with its environment.

WGBH Educational Foundation

2010-12-14

411

Novel Structure and Function of Typhoid Toxin

... July 29, 2013 Novel Structure and Function of Typhoid Toxin Researchers gained important insights into the reasons why Salmonella typhi , the cause of typhoid fever, is so dangerous. The findings could help ...

412

New Parametrizations for the Photon Structure Function

International Nuclear Information System (INIS)

In the last year four new parametrizations of the Hadronic Photon Structure Function at Next to Leading Order have appeared. In this talk, I briefly review the main features of the three of them: the FFNSCJK, CJK and AFG. (author)

413

Neutron structure function moments at leading twist

Digital Repository Infrastructure Vision for European Research (DRIVER)

The experimental data on F2 structure functions of the proton and deuteron were used to construct their moments. In particular, recent measurements performed with CLAS detector at Jefferson Lab allowed to extend our knowledge of structure functions in the large-x region. The phenomenological analysis of these experimental moments in terms of the Operator Product Expansion permitted to separate the leading and higher twist contributions. Applying nuclear corrections to extrac...

Osipenko, M.; Simula, S.; Kulagin, S.; Ricco, G.; Collaboration, Clas

2006-01-01

414

Proton Structure Function Measurements from HERA

Digital Repository Infrastructure Vision for European Research (DRIVER)

Measurements of proton structure functions made in neutral and charged current interactions at HERA are discussed, covering four-momentum transfers Q^2 from about 0.5 GeV^2 to 30000 GeV^2. The results include the rise of the structure function F2 towards small x and electro-weak effects at high Q^2. QCD fits made by the H1 and ZEUS collaborations provide both, parton densities with uncertainties, and precise alpha_s determinations.

Gayler, Joerg

2002-01-01

415

Structure Functions of Electroweak Bosons and Leptons

Digital Repository Infrastructure Vision for European Research (DRIVER)

The QCD structure of the electroweak bosons is reviewed and the lepton structure function is defined and calculated. The leading order splitting functions of electron into quarks are extracted, showing an important contribution from $\\gamma$-$Z$ interference. Leading logarithmic QCD evolution equations are constructed and solved in the asymptotic region where log$^2$ behaviour of the parton densities is observed. Possible applications with clear manifestation of 'resolved' p...

Slominski, Wojciech; Szwed, Jerzy

1996-01-01

416

Polarized Structure Functions: a Theoretical Update

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ho...

Forte, Stefano

1995-01-01

417

Recent Structure Function Results from CCFR

A new structure function analysis of CCFR deep inelastic nu-N and nubar-N scattering data is presented for previously unexplored kinematic regions down to Bjorken x=0.0045 and Q^2=0.3 GeV^2. Comparisons to charged lepton scattering data from NMC and E665 experiments are made and the behavior of the structure function F2_nu is studied in the limit Q^2 -> 0

Fleming, B T; Alton, A; Arroyo, C G; Avvakumov, S; De Barbaro, L; De Barbaro, P; Bazarko, A O; Bernstein, R H; Bodek, Arie; Bolton, T; Brau, J E; Buchholz, D; Budd, H S; Bugel, L; Conrad, J; Drucker, R B; 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; McNulty, C; Mishra, S R; Naples, D; Nienaber, P; Romosan, A; Sakumoto, W K; Schellman, H; Sciulli, F J; Seligman, W G; Shaevitz, M H; Smith, W H; Spentzouris, P; Stern, E G; Vakili, M; Vaitaitis, A G; Vakili, M; Yang, U K; Yu, J; Zeller, G P; Zimmerman, E D

2000-01-01

418

Polarized deuteron structure functions at small x

We investigate shadowing corrections to the polarized deuteron structure functions g_1^d and b_1. In the kinematic domain of current fixed target experiments we observe that shadowing effects in g_1^d are approximately twice as large as for the unpolarized structure function F_2^d. Furthermore, we find that b_1 is surprisingly large at x < 0.1 and receives dominant contributions from coherent double scattering.

Edelmann, J; Weise, W

1997-01-01

419

Proton structure functions and quark orbital motion

Digital Repository Infrastructure Vision for European Research (DRIVER)

Covariant version of the quark-parton model is studied. Dependence of the structure functions on the 3D quark intrinsic motion is discussed. The important role of the quark orbital momentum, which is a particular case of intrinsic motion, appears as a direct consequence of the covariant description. Effect of orbital motion is substantial especially for polarized structure functions. At the same time, the procedure for obtaining the quark momentum distribution from the struc...

Zavada, Petr

2006-01-01

420

Functional annotation strategy for protein structures

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. MEDSuMo 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 a...

Doppelt, Olivia; Moriaud, Fabrice; Bornot, Aure?lie; Brevern, Alexandre

2007-01-01

421

Proton and neutron polarized structure functions from low to high Q**2

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phenomenological parameterizations of proton and neutron polarized structure functions, g1p and g1n, are developed for x > 0.02 using deep inelastic data up to ~ 50 (GeV/c)**2 as well as available experimental results on photo- and electro-production of nucleon resonances. The generalized Drell-Hearn-Gerasimov sum rules are predicted from low to high values of Q**2 and compared with proton and neutron data. Furthermore, the main results of the power correction analysis carri...

Simula, S.; Osipenko, M.; Ricco, G.; Taiuti, M.

2002-01-01

422

Density functional theory and electronic structure

International Nuclear Information System (INIS)

The paper presents an overview of the density functional theory and provides a brief appraisal of the latest developments of the theory. Particular emphasis is placed on the understanding of the electronic structure of materials via the density functional theory. 37 refs, 1 tab

423

Nucleon properties inside compressed nuclear matter

Our model calculations performed in the frame of the Bag Model (BM) approach show the modifications of nucleon mass, nucleon radius and a Parton Distribution Function (PDF) in Nuclear Matter (NM) above the saturation point. They originated from the pressure correction to the nucleon rest energy. Similar correction leads to conservation of a nuclear longitudinal momenta - essential in the explanation of the EMC effect at the saturation point of NM. Presented finite pressure corrections are generalization of the Hugenholtz-van Hove theorem valid for finite nucleon sizes inside NM.

Rozynek, Jacek

2014-01-01

424

Structure-function studies of epoxide hydrolases

Digital Repository Infrastructure Vision for European Research (DRIVER)

Epoxides are three-membered cyclic ethers formed in cells via several metabolic pathways. Epoxide hydrolases (EHs) are enzymes that hydrolyse epoxides to the corresponding diols. The main goal of this thesis was to investigate the structures of EHs from the alpha/beta-hydrolase family. The first part concerns the structural and functional analysis of a protein-water channel found in EHs in many plants. Thermostability studies, sequence analysis and determination of the x-ray structure of a mu...

Naworyta, Agata

2010-01-01

425

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

426

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

427

Three-Nucleon Photodisintegration of 3He

The three-nucleon photodisintegration of 3He has been calculated in the whole phase space using consistent Faddeev equations for the three-nucleon bound and scattering states. Modern nucleon-nucleon and 3N forces have been applied as well as different approaches to nuclear currents. Phase space regions are localized where 3N force effects are especially large. In addition semi-exclusive cross sections for 3He(gamma,N) have been predicted which carry interesting peak structures. Finally some data for the exclusive 3N breakup process of 3He and its total breakup cross section have been compared to theory.

Skibinski, R; Witala, H; Glöckle, W; Kamada, H; Nogga, A

2003-01-01

428

EMC effect and nuclear structure functions

International Nuclear Information System (INIS)

We analyze experimental data of nuclear structure function ratios F2A/F2D for obtaining optimum parton distribution functions (PDFs) in nuclei. Then, uncertainties of the nuclear PDFs are estimated by the Hessian method. Parametrization of nuclear parton distribution is investigated in the leading order of ?s. The parton distribution are provided at Q2=1GeV2 with a number of parameters, which are determined by a ?2 analysis of the data on nuclear structure function. From the analysis, we propose parton distributions at Q2=1GeV2 for nuclei from deuteron to heavy ones with a mass number A?208

429

Universality of nucleon–nucleon short-range correlations and nucleon momentum distributions

International Nuclear Information System (INIS)

By analyzing recent microscopic many-body calculations of few-nucleon systems and complex nuclei performed by different groups in terms of realistic nucleon–nucleon (NN) interactions, it is shown that NN short-range correlations (SRCs) have a universal character, in that the correlation hole that they produce in nuclei appears to be almost A-independent and similar to the correlation hole in the deuteron. The correlation hole creates high-momentum components, missing in a mean-field (MF) description and exhibiting several scaling properties and a peculiar spin–isospin structure. In particular, the momentum distribution of a pair of nucleons in spin–isospin state (ST) = (10), depending upon the pair relative (krel) and center-of-mass (c.m.) (Kc.m.) momenta, as well as upon the angle ? between them, exhibits a remarkable property: in the region krel?2 fm-1 and Kc.m.?1 fm-1, the relative and c.m. motions are decoupled and the two-nucleon momentum distribution factorizes into the deuteron momentum distribution and an A-dependent momentum distribution describing the c.m. motion of the pair in the medium. The impact of these and other properties of one- and two-nucleon momentum distributions on various nuclear phenomena, on ab initio calculations in terms of low-momentum interactions, as well as on ongoing experimental investigations of SRCs, are briefly commented. (author)

430

Magnetism and Structure in Functional Materials

Magnetism and Structure in Functional Materials addresses three distinct but related topics: (i) magnetoelastic materials such as magnetic martensites and magnetic shape memory alloys, (ii) the magnetocaloric effect related to magnetostructural transitions, and (iii) colossal magnetoresistance (CMR) and related magnanites. The goal is to identify common underlying principles in these classes of materials that are relevant for optimizing various functionalities. The emergence of apparently different magnetic/structural phenomena in disparate classes of materials clearly points to a need for common concepts in order to achieve a broader understanding of the interplay between magnetism and structure in this general class of new functional materials exhibiting ever more complex microstructure and function. The topic is interdisciplinary in nature and the contributors correspondingly include physicists, materials scientists and engineers. Likewise the book will appeal to scientists from all these areas.

Planes, Antoni; Saxena, Avadh

2005-01-01

431

International Nuclear Information System (INIS)

Characteristics of protons with the p > or approximately 0.7 GeV/c momentum and some properties of negative pions are analysed for CTa collisions at 4.2 GeV/c per nucleon as functions of a cummulative variable ?0. The proton emission has been detected for ?0 > or approximately1, while the dependence of the proton characteristics and the distribution of accompanying ?- mesons is changed qualitatively in the region ?0 approximately 1. The experimental results are compared with predictions of the cascade model. The model describes satisfactorily the mean characteristics of particles accompanying the cumulative proton, but in the cumulative region, ?0 > or approximately 1 it does not agree with the experimental mean characteristics of protons having the maximal ?0 in the event

432

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. PMID:24016222

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

2013-08-23

433

The Nucleon-Nucleon Interaction in a Chiral Constituent Quark Model

We study the short-range nucleon-nucleon interaction in a chiral constituent quark model by diagonalizing a Hamiltonian comprising a linear confinement and a Goldstone boson exchange interaction between quarks. The six-quark harmonic oscillator basis contains up to two excitation quanta. We show that the highly dominant configuration is $\\mid s^4p^2[42]_O [51]_{FS}>$ due to its specific flavour-spin symmetry. Using the Born-Oppenheimer approximation we find a strong effective repulsion at zero separation between nucleons in both $^3S_1$ and $^1S_0$ channels. The symmetry structure of the highly dominant configuration implies the existence of a node in the S-wave relative motion wave function at short distances. The amplitude of the oscillation of the wave function at short range will be however strongly suppressed. We discuss the mechanism leading to the effective short-range repulsion within the chiral constituent quark model as compared to that related with the one-gluon exchange interaction.

Stancu, F; Glozman, L Ya; Stancu, Fl.

1997-01-01

434

Reynolds number Scaling of Streamwise Structure Functions

Turbulent velocity structure functions have been measured in the Princeton Superpipe facility using hot wire anemometry. In this facility, fully-developed turbulent pipe flow is developed over a very large range of Reynolds numbers, 31 × 10^3 to 35 × 10^6 (based on average velocity and diameter). The 1/4th through 3rd order structure functions were measured over a range of Reynolds Numbers from 120 × 10^3 to 16 × 10^6. Preliminary comparisons with theory by Yakhot [1996] are encouraging.

Schmanske, M.; Yakhot, V.; Smits, A. J.

1996-11-01

435

Comparison of ?Z-structure function models

International Nuclear Information System (INIS)

The ?Z-box is an important contribution to the proton's weak charge. The ?Z-box is calculated dispersively and depends on ?Z-structure functions, F1,2,3?Z(x,Q2). At present there is no data for these structure functions and they must be modeled by modifying existing fits to electromagnetic data. Each group that has studied the ?Z-box used different modifications. The results of the PVDIS experiment at Jefferson Lab may provide a first test of the validity of each group's models. I present details of the different models and their predictions for the PVDIS result

436

Family-changes In Structure And Functions

Directory of Open Access Journals (Sweden)

Full Text Available Family, being the most basic social institution of the human society, has undergone some basic changes over a period of time due to some factors and needs. This paper is an attempt to sketch a picture about the modern family and how this has undergone changes and nature of changes since its inception. The validity of the definitional characteristics, the factors that have exerted forces on family for the structural and functional changes, the actual structural changes that have occurred, the functional changes that have occurred have also been appeared in the relevant sections of the paper.

Sambhaji R. Warangule Patil

2013-11-01

437

Few-Nucleon Calculations and Correlations

Digital Repository Infrastructure Vision for European Research (DRIVER)

Some present day results for few-nucleon bound state, two-nucleon correlation functions and scattering observables are briefly reviewed. The old idea of the Coulomb sum rule as a way to extract the pp correlation function is reconsidered. It appears to be an ideal case to probe properties of the density operator and the ground state wave functions without disturbances of final state interactions (FSI) in exclusive electron scattering on 3He. Also exclusive photodisintegratio...

Glockle, W.; Kamada, H.; Golak, J.; Nogga, A.; Witala, H.; Skibinski, R.; Kuros-zolnierczuk, J.

2001-01-01

438

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

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

439

The spin dependent structure function g{sub 1} of the deuteron and the proton

Energy Technology Data Exchange (ETDEWEB)

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 g{sub 1}, 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 g{sub 1}{sup p} 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 g{sub 1}{sup p} and g{sub 1}{sup d} to test a fundamental sum rule in quantum chromodynamics (QCD), the Bjorken sum rule. (orig./WL).

Klostermann, L.

1995-02-27

440

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)

441

A Study of Nucleon Spin Struture from Quantum Chromodynamics

Digital Repository Infrastructure Vision for European Research (DRIVER)

I present an introduction to the field of Quantum Chromodynamics (QCD) with emphasis on nucleon spin structure and perturbative methods. After a somewhat comprehensive overview of perturbative QCD, including the systematics of renormalization, I introduce deeply-inelastic scattering and deeply-virtual Compton scattering along with the nonperturbative distribution functions appearing in these processes. I show how these processes can be used to extract the distribution of lon...

Osborne, Jonathan

2001-01-01

442

Soudan 2 nucleon decay experiment

International Nuclear Information System (INIS)

The Soudan 2 nucleon decay experiment consists of a 1.1 Kton fine grained iron tracking calorimeter. It has a very isotropic detection structure which along with its flexible trigger will allow detection of multiparticle and neutrino proton decay modes. The detector has now entered its construction stage

443

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

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

444

International Nuclear Information System (INIS)

The double differential cross sections are measured as a function of the mass number and total kinetic energy for products of the 40Ar (220 MeV)+124Sn, 40Ar(220 MeV)+108Ag, 40Ar(220 MeV)+139La and 64Zn (315 MeV)+122Sn, 64Zn(315 MeV)+108Ag, 64Zn (315 MeV)+139La reactions. The effect of specific features of the shell structure of colliding nuclei on the maximum position of the fragment mass distribution is studied within the microscopic approach. A qualitative difference in dependences of the maximum position on the total kinetic energy of products of the reactions with 64Zn and 40Ar observed experimentally points to the shell structure of interacting nuclei

445

Structure functions: Their status and implications

International Nuclear Information System (INIS)

I discuss the current status of structure functions. Attention is given to the uncertainties in them and the implications of these uncertainties for experimental predictions. I indicate which experiments are capable of removing these uncertainties. 17 refs., 17 figs., 1 tab

446

Polynomial Structure of Topological String Partition Functions

We review the polynomial structure of the topological string partition functions as solutions to the holomorphic anomaly equations. We also explain the connection between the ring of propagators defined from special K\\"ahler geometry and the ring of almost-holomorphic modular forms defined on modular curves.

Zhou, Jie

2015-01-01

447

Bioturbation, ecosystem functioning and community structure

Directory of Open Access Journals (Sweden)

Full Text Available The effect of community structure on the functioning of the ecosystem is an important issue in ecology due to continuing global species loss. The influence of infaunal community structure on the functioning of marine systems is proposed here to act primarily through bioturbation of the sediment. Nutrient concentration in the water column, generated by release from the sediment, was used as a measure of ecosystem functioning. In situ and laboratory experiments showed a significant difference in nutrient concentrations with different species treatments. Bioturbation profiles showing the incorporation of tracer particles also differed between communities with different dominant species. The behavioural differences between infaunal species, generating different modes and rates of bioturbation, are therefore proposed to influence nutrient release. The presence and quantity of bioturbating infauna also influenced the amount of sediment suspended in the water column. The increase in surface area available for microbial activity may generate an increase in nutrient cycling. Abiotic influences on sediment structure, such as flow, may have a similar effect on nutrient concentration. Annular flumes used in both laboratory and in situ experiments to generate flow conditions produced a significant increase in ammonia (NH4-N production in macrofaunal treatments. Flow may influence the behaviour of macrofaunal species, causing changes in NH4-N production through modifying bioturbation of the sediment. Keywords: bioturbation, community structure, ccosystem functioning, estuaries, flow, infauna

C. L. Biles

2002-01-01

448

Phenomenology of Deep Inelastic Scattering Structure Functions

I review recent progress in analysing deep inelastic scattering structure functions in global analyses. The new ingredients are new data and attempts to incorporate heavy quarks consistently. A new way of including the resummation of large $\\log 1/x$ terms is discussed.

Roberts, R G

1997-01-01

449

Resonance contribution to electromagnetic structure functions

International Nuclear Information System (INIS)

The part of the pion and proton electromagnetic structure functions due to direct channel resonances in the virtual Compton amplitude is discussed. After a phenomenological discussion, based on the work of Bloom and Gilman, of resonance production in inelastic electroproduction, the single resonance contribution to the pion and proton structure functions is expressed in terms of transition form factors. Froissart-Gribov representations of the Compton amplitude partial waves are presented and are used to specify the spin dependence of the transition form factors. The dependence of the form factors on momentum transfer and resonance mass is assumed on the basis of the behavior of exclusive resonance electroproduction. The single resonance contributions are summed in the Bjorken limit, and the result exhibits Bjorken scaling. Transverse photons are found to dominate in the Bjorken limit, and the threshold behavior of the resonant part of the structure functions is related to the asymptotic behavior of exclusive form factors at large momentum transfer. The resonant parts of the annihilation structure functions are not in general given by simple analytic continuation in the scaling vari

450

Medium effects on nucleon properties

International Nuclear Information System (INIS)

The modifications of the nucleon structure due to the presence of an external baryon medium are investigated in a chiral nonlinear quark-meson theory. To this end the Nambu-Jona-Lasinio approach is used to evaluate the pion decay constant and the pion and sigma masses at finite density. Those meson properties serve to fix the parameters of the linear chiral sigma model, which is then solved in a variational projected mean field approach in order to obtain nucleon properties. The proton radius shows an increase of 22% and the nucleon mass a decrease of 17% if the medium reaches nuclear matter density. The axial vector coupling constant is reduced by about 10% and the electric form factors show remarkable changes at q?1 GeV/c. (orig.)

451

International Nuclear Information System (INIS)

We review experimental results concerning polarization phenomena in nucleon-nucleon scattering in which both the elastic scattering and hadron-production reaction are included. We also present summary of S = 0 dibaryon resonances and candidates by reviewing experimental data in the nucleon-nucleon system, ?d channel, ?d elastic scattering, pp ? ?d channel, deuteron break-up reactions, and narrow structures in missing-mass spectra. 93 refs., 26 figs

452

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

453

A narrow structure in the excitation function of eta-photoproduction off the neutron

The photoproduction of $\\eta$-mesons off nucleons bound in $^2$H and $^3$He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the $\\eta\\rightarrow 2\\gamma$ and $\\eta\\rightarrow 3\\pi^0$ decays and the recoil nucleons were detected with an almost $4\\pi$ electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of $\\gamma n\\rightarrow n\\eta$. The results from the two measurements are consistent taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are $W$ = (1670$\\pm$5) MeV and $\\Gamma$ =(30$\\pm$15) MeV. For the first time precise results for the angular dependence of this structure have been ext...

Werthmueller, D; Keshelashvili, I; Aguar-Bartolome, P; Ahrens, J; Annand, J R M; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Demissie, B; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Glazier, D I; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Huber, G M; Jaegle, I; Jahn, O; Jude, T C; Kaeser, A; Kashevarov, V L; Kondratiev, R; Korolija, M; Kruglov, S P; Krusche, B; Kulbardis, A; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McNicoll, E F; Metag, V; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S N; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D; Starostin, A; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P

2013-01-01

454

Structure function of a damped harmonic oscillator

International Nuclear Information System (INIS)

Following the Caldeira-Leggett approach to describe dissipative quantum systems the structure function for a harmonic oscillator with Ohmic dissipation is evaluated by an analytic continuation from Euclidean to real time. The analytic properties of the Fourier transform of the structure function with respect to the energy transfer (the 'characteristic function') are studied and utilized. In the one-parameter model of Ohmic dissipation we show explicitly that the broadening of excited states increases with the state number without violating sum rules. Analytic and numerical results suggest that this is a phenomenologically relevant, consistent model to include the coupling of a single (sub)nuclear particle to unobserved and complex degrees of freedom

455

We measured simultaneously the 4He(eep), 4He(eepp), and 4He(e,e'pn) reactions at Q^2=2 [GeV/c]2 and x_B>1, for a (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum in a region where the nucleon-nucleon force is expected to change from predominantly tensor to repulsive. Neutron-proton pairs dominate the high-momentum tail of the nucleon momentum distributions, but their abundance is reduced as the nucleon momentum increases beyond ~500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum in the range we studied. Our data are compared with ab-initio calculations of two-nucleon momentum distributions in 4He.

Muangma, I Korover N; Shneor, R; Sulkosky, V; Kelleher, A; Gilad, S; Higinbotham, D W; Watson, E Piasetzky J; Wood, S; Rakhman, Abdurahim; Aguilera, P; Ahmed, Z; Albataineh, H; Allada, K; Anderson, B; Anez, D; Aniol, K; Annand, J; Armstrong, W; Arrington, J; Averett, T; Badman, T; Baghdasaryan, H; Bai, X; Beck, A; Beck, S; Bellini, V; Benmokhtar, F; Bertozzi, W; Bittner, J; Boeglin, W; Camsonne, A; Chen, C; Chen, J -P; Chirapatpimol, K; Cisbani, E; Dalton, M; Daniel, A; Day, D; de Jager, C W; De Leo, R; Deconinck, W; Defurne, M; Flay, D; Fomin, N; Friend, M; Frullani, S; Fuchey, E; Garibaldi, F; Gaskell, D; Gilman, R; Glamazdin, O; Gu, C; Gueye, P; Hamilton, D; Hanretty, C; Hansen, O; Shabestari, M Hashemi; Holmstrom, T; Huang, M; Iqbal, S; Jin, G; Kalantarians, N; Kang, H; Khandaker, M; LeRose, J; Leckey, J; Lindgren, R; Long, E; Mammei, J; Margaziotis, D J; Markowitz, P; Jimenez-Arguello, A Marti; Meekins, D; Meziani, Z; Michaels, R; Mihovilovic, M; Monaghan, P; Camacho, C Munoz; Norum, B; Nuruzzaman,; Pan, K; Phillips, S; Pomerantz, I; Posik, M; Punjabi, V; Qian, X; Qiang, Y; Qiu, X; Reimer, P E; Riordan, S; Ron, G; Rondon-Aramayo, O; Saha, A; Schulte, E; Selvy, L; Shahinyan, A; Sirca, S; Sjoegren, J; Slifer, K; Solvignon, P; Sparveris, N; Subedi, R; Tireman, W; Wang, D; Weinstein, L B; Wojtsekhowski, B; Yan, W; Yaron, I; Ye, Z; Zhan, X; Zhang, J; Zhang, Y; Zhao, B; Zhao, Z; Zheng, X; Zhu, P; Zielinski, R

2014-01-01

456

Proton and neutron polarized targets for nucleon-nucleon experiments at SATURNE II

International Nuclear Information System (INIS)

A SATURNE polarized target has been used for nucleon-nucleon elastic scattering and transmission experiments for 15 years. The polarized proton target is a 70 cm3 cartridge loaded with Pentanol-2. For polarized neutron target, two cartridges loaded with 6LiD and 6LiH are set in the refrigerator and can be quickly inserted in the beam. First experiments using 6Li products in quasielastic pp or pn analyzing power measurements are compared with the same observables measured in a free nucleon-nucleon scattering using polarized proton targets. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon-nucleon scattering is shown for different targets. (author)

457

Optimizing nondecomposable loss functions in structured prediction.

We develop an algorithm for structured prediction with nondecomposable performance measures. The algorithm learns parameters of Markov Random Fields (MRFs) and can be applied to multivariate performance measures. Examples include performance measures such as F? score (natural language processing), intersection over union (object category segmentation), Precision/Recall at k (search engines), and ROC area (binary classifiers). We attack this optimization problem by approximating the loss function with a piecewise linear function. The loss augmented inference forms a Quadratic Program (QP), which we solve using LP relaxation. We apply this approach to two tasks: object class-specific segmentation and human action retrieval from videos. We show significant improvement over baseline approaches that either use simple loss functions or simple scoring functions on the PASCAL VOC and H3D Segmentation datasets, and a nursing home action recognition dataset. PMID:22868650

Ranjbar, Mani; Lan, Tian; Wang, Yang; Robinovitch, Steven N; Li, Ze-Nian; Mori, Greg

2013-04-01

458

The form factors of the nucleons

International Nuclear Information System (INIS)

The author demonstrates that a relativistic constituent quark model can give nucleon form factors that agree well with recent, accurate measurements. The relativistic features of the model and the specific form of the wave function are essential for the result

459

Structure of BRS-invariant local functionals

International Nuclear Information System (INIS)

For a large class of gauge theories a nilpotent BRS-operator s is constructed and its cohomology in the space of local functionals of the off-shell fields is shown to be isomorphic to the cohomology of s=s+d on functions f(C,T) of tensor fields T and of variables C which are constructed of the ghosts and the connection forms. The result allows general statements about the structure of invariant classical actions and anomaly cadidates whose BRS-variation vanishes off-shell. The assumptions under which the result holds are thoroughly discussed. (orig.)

460

The structure and function of endophilin proteins

DEFF Research Database (Denmark)

Members of the BAR domain protein superfamily are essential elements of cellular traffic. Endophilins are among the best studied BAR domain proteins. They have a prominent function in synaptic vesicle endocytosis (SVE), receptor trafficking and apoptosis, and in other processes that require remodeling of the membrane structure. Here, we discuss the role of endophilins in these processes and summarize novel insights into the molecular aspects of endophilin function. Also, we discuss phosphorylation of endophilins and how this and other mechanisms may contribute to disease.

Kjaerulff, Ole; Brodin, Lennart

2011-01-01

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Abrupt structural transitions involving functionally optimal networks

We show analytically that abrupt structural transitions can arise in functionally optimal networks, driven by small changes in the level of transport congestion. Our findings are based on an exactly solvable model system which mimics a variety of biological and social