Polarized structure functions of nucleons and nuclei
Bentz, W.; Cloët, I. C.; Ito, T.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia); Yazaki, K
2007-01-01
We determine the quark distributions and structure functions for both unpolarized and polarized DIS of leptons on nucleons and nuclei. The scalar and vector mean fields in the nucleus modify the motion of the quarks inside the nucleons. By taking into account this medium modification, we are able to reproduce the experimental data on the unpolarized EMC effect, and to make predictions for the polarized EMC effect. We discuss examples of nuclei where the polarized EMC effect ...
Experimental results on polarized nucleon structure functions
Energy Technology Data Exchange (ETDEWEB)
Ketel, T.J. [Department of Physics and Astronomy, Free University Amsterdam (Netherlands); Spin Muon Collaboration at CERN
1998-05-01
Experimental results of deep inelastic scattering of polarized leptons from polarized target nucleons are reviewed. Accurate values of the spin dependent structure function g{sub 1} (x) were obtained in experiments covering a large kinematic range. The combination of all experimental results confirms the validity of the Bjorken sum rule. (author) 14 refs, 7 figs, 2 tabs
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
Nucleon structure functions with domain wall fermions
Orginos, K; Ohta, S; Orginos, Kostas; Blum, Thomas; Ohta, Shigemi
2006-01-01
We present a quenched lattice QCD calculation of the first few moments of the polarized and un-polarized structure functions of the nucleon. Our calculations are done using domain wall fermions and the DBW2 gauge action with inverse lattice spacing ~1.3GeV, physical volume approximatelly (2.4 fm)^3, and light quark masses down to about 1/4 the strange quark mass. Values of the individual moments are found to be significantly larger than experiment, as in past lattice calculations, but interestingly the chiral symmetry of domain wall fermions allows for a precise determination of the ratio of the flavor non-singlet momentum fraction to the helicity distribution, which is in very good agreement with experiment. We discuss the implications of this result. Next, we show that the chiral symmetry of domain wall fermions is useful in eliminating mixing of power divergent lower dimensional operators with twist-3 operators. Finally, we find the isovector tensor charge at renormalization scale 2 GeV in the MS bar schem...
Nucleon structure functions at small $x$ via holographic Pomeron exchange
Watanabe, Akira
2015-01-01
The analysis on nucleon structure functions at small Bjorken $x$ in the framework of holographic QCD is presented. In the model setup, the complicated nonperturbative interaction between the virtual photon and the target nucleon is described via the Pomeron exchange, which corresponds to the reggeized graviton exchange in the AdS space. We show that our calculations for both $F_2$ and $F_L$ structure functions are in agreement with the experimental data measured at HERA.
A no extensive statistical model for the nucleon structure function
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Instituto de Ciencia, Engenharia e Tecnologia - ICET, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Campus do Mucuri, Rua do Cruzeiro 01, Jardim Sao Paulo, 39803-371, Teofilo Otoni, Minas Gerais (Brazil)
2013-03-25
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.
Spin Dependent Structure Functions of Nucleons and Nuclei
Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
1994-01-01
We review recent progress in the understanding of the spin structure of the nucleon. For the free nucleon the issues addressed include the status of the Bjorken and Ellis-Jaffe sum-rules and the role of the axial anomaly. We outline recent work connecting the quark models familiar from hadron spectroscopy to the spin and flavour dependence of the parton distributions. Finally we review the current understanding of nuclear spin structure functions and particularly the extract...
Experiments on nucleon spin-dependent structure functions
Energy Technology Data Exchange (ETDEWEB)
Igo, G. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Hughes, V.W. [Yale Univ., New Haven, CT (United States). Dept. of Physics
1991-12-31
In this presentation, the earlier measurements of the spin-dependent structure function of the proton in experiments at SLAC and at CERN are reviewed. In addition several new deep inelastic scattering experiments to measure the spin-dependent structure functions of the nucleon, both proton and neutron, will be discussed.
Experiments on nucleon spin-dependent structure functions
Energy Technology Data Exchange (ETDEWEB)
Igo, G. (California Univ., Los Angeles, CA (United States). Dept. of Physics); Hughes, V.W. (Yale Univ., New Haven, CT (United States). Dept. of Physics)
1991-01-01
In this presentation, the earlier measurements of the spin-dependent structure function of the proton in experiments at SLAC and at CERN are reviewed. In addition several new deep inelastic scattering experiments to measure the spin-dependent structure functions of the nucleon, both proton and neutron, will be discussed.
Nucleon axial charge and structure functions with domain wall fermions
Ohta, S; Ohta, Shigemi; Orginos, Kostas
2003-01-01
We report the current status of RBCK calculations on nucleon structure with both quenched and unquenched lattice QCD. The combination of domain wall fermions and DBW2 gauge action works well for isovector vector and axial charges, and moments of structure functions _q, d_1, and _{\\delta q}.
Energy Technology Data Exchange (ETDEWEB)
Bertini, M.
1995-05-12
This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F{sub 2}) and polarized (g{sub 1}) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F{sub 2} and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions g{sup p,n,d} and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends.
The nucleon structure function and the quark effective potential
International Nuclear Information System (INIS)
A statistical quark model is considered in order to reproduce the nucleon structure function , by using a temperature parameter to adjust the Gottfried sum rule. In the present statistical model, the quark levels in the nucleon are generated by a Dirac equation with harmonic scalar plus vector potential. We note that a good fit for the ratio between the structure functions of the neutron and proton, F2n/F2p, can be obtained if different strengths are used for the effective confining potentials of the up and down quarks. (author)
Truncated Moment Analysis of Nucleon Structure Functions
Energy Technology Data Exchange (ETDEWEB)
A. Psaker; W. Melnitchouk; M. E. Christy; C. E. Keppel
2007-11-16
We employ a novel new approach using "truncated" moments, or integrals of structure functions over restricted regions of x, to study local quark-hadron duality, and the degree to which individual resonance regions are dominated by leading twists. Because truncated moments obey the same Q^2 evolution equations as the leading twist parton distributions, this approach makes possible for the first time a description of resonance region data and the phenomenon of quark-hadron duality directly from QCD.
Measurements of spin structure functions of the nucleon
International Nuclear Information System (INIS)
After a recall of the history of researches on nucleon structure, this research thesis addresses the measurements of spin structure functions of a proton and of a neutron as they have been performed during the NA47 experiment at the CERN. The author first develops the formalism of the deeply inelastic scattering of polarised leptons on polarised nucleons, with a peculiar attention to the definition of structure functions. The various obtained results are re-determined in a more general framework based on the Operator Product Expansion formalism which allows, within the framework of Quantum Chromodynamics, to relate some moments of structure functions to elements of hadron matrices. The author then describes the experimental situation for the measurement of the proton spin structure function at the end of the 1980's, and presents the experimental installation of the NA47 experiment. Reconstruction programs are then addressed, and the author explains how he determines, event by event, the kinematics of the highly inelastic scattering of a muon on a nucleon, and the vertex position within the target. Sources of errors are identified, and the author presents methods aimed at reducing and at assessing the detection efficiency of all detectors, and of their evolutions in time. The author explains how results on asymmetries and structure functions are extracted from counting rates associated with two cells, as well as the method of calculation of various systematic errors associated with these asymmetries and structure functions. He finally presents results obtained for the measurement of the spin structure function for the proton and for the deuton. The Ellis-Jaffe sum rule is then tested, and spin share of the nucleon born by quarks is determined. Results are compared with those of other experiments, and the Bjorken sum rule is also tested
Detailed Measurements of Structure Functions from Nucleons and Nuclei
2002-01-01
The experiment will study deep inelastic muon nucleon scattering in a wide range of Q|2~(1-200 (GeV/c)|2) and x~(0.005-0.75). The main aims of the experiment are: \\item a)~~~~Detailed measurements of the nuclear dependence of the structure function F^2|A, of R~=~@s^L/@s^T and of the cross-section for J/@y production. They will provide a basis for the understanding of the EMC effect: the modification of quark and gluon distributions due to the nuclear environment. \\item b)~~~~A simultaneous high luminosity measurement of the structure function F^2 on hydrogen and deuterium. This will provide substantially improved accuracy in the knowledge of the neutron structure function F^2|n, of F^2|p-F^2|n and F^2|n/F^2|p and their Q|2 dependence. Furthermore, the data will allow a determination of the strong coupling constant @a^s(Q|2) with reduced experimental and theoretical uncertainties as well as of the ratio of the down to up quark distributions in the valence region. Due to the large x range covered by the experim...
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
Bound nucleon structure function in the picture of relativistic constituent quarks
International Nuclear Information System (INIS)
The structure function F2N of nucleons in the deuterium, carbon and iron nuclei is calculated as a function of Q2 in two approaches: taking into account the nucleon swelling in nuclei due to the partial deconfinement of quarks in nuclear medium; in the conventional approach of nuclear physics, taking into account the getting off the mass shell of the bound nucleon and Fermi motion in nucleons. It is shown that the conventional approach of nuclear physics does not explain the EMC effect in the region of small x
On the off-mass-shell deformation of the nucleon structure function
Umnikov, A Yu; Kaptari, L P; Umnikov, A Yu; Khanna, F C; Kaptari, L P
1994-01-01
The off-mass-shell behavior of the nucleon structure function, F_2^N, is studied within an approach motivated by the Sullivan model. Deep inelastic scattering on the nucleon is considered in the second order in the pion-nucleon coupling constant, corresponding to the dressing of the bare nucleons by the mesonic cloud. The inclusive and semi-inclusive deep inelastic processes on the deuteron involving off-shell nucleons are considered. A deformation of the mesonic cloud for the off-mass-shell nucleon, compared to the free one, generates observable effects in deep inelastic scattering. In particular, it leads to the breakdown of the convolution model, i.e. the deuteron structure functions are not expressed through the free nucleon structure function. Analysis of the semi-inclusive deep inelastic scattering on the deuteron, in the spectator approximation, shows that this reaction opens new possibilities to study the role of the off-shell effects in determining in detail the nucleon structure function.
Off-shell pion structure function and flavor asymmetry in the nucleon sea
Shigetani, Takayuki; Suzuki, Katsuhiko; Toki, Hiroshi
1995-01-01
We study off-shell effects of the pion cloud on the sea quark distribution in the nucleon. The structure function of the off-mass-shell pion is obtained within the Nambu and Jona-Lasinio model, where the shape of the distribution function depends on the pion momentum. By using the momentum dependent pion structure function, the SU(2) flavor asymmetry in the nucleon see is reexamined within the pionic model, in which the sea quark distribution of the nucleon is given as a con...
Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons
Energy Technology Data Exchange (ETDEWEB)
Bodek, Arie [University of Rochester, Rochester, NY
2015-09-01
We present preliminary results on an experimental study of the nuclear modification of the longitudinal (sL) and transverse (sT ) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= sL=sT for nuclei (RA) and for deuterium (RD) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, RA < RD.
Linear estimates of structure functions from deep inelastic lepton-nucleon scattering data. Part 2
International Nuclear Information System (INIS)
The paper concerns the linear estimation of structure functions from (anti)neutrino-nucleon scattering. The expressions obtained for the structure functions estimate provide correct analysis of their random error and the bias. The bias arises because of the finite number of experimental data and the finite resolution of experiment. 10 refs
Off-shell pion structure function and flavor asymmetry in the nucleon sea
Shigetani, T; Toki, H; Shigetani, Takayuki; Suzuki, Katsuhiko; Toki, Hiroshi
1995-01-01
We study off-shell effects of the pion cloud on the sea quark distribution in the nucleon. The structure function of the off-mass-shell pion is obtained within the Nambu and Jona-Lasinio model, where the shape of the distribution function depends on the pion momentum. By using the momentum dependent pion structure function, the SU(2) flavor asymmetry in the nucleon see is reexamined within the pionic model, in which the sea quark distribution of the nucleon is given as a convolution of the off-shell pion structure function. We calculate experimentally observed quantities related to the SU(2) asymmetry of the nucleon sea such as the Gottfried sum and the Drell-Yan cross section ratios, and find these quantities are insensitive to the off-shell effects of the pions structure function. However, the x dependence of \\bar{u}-\\bar{d} calculated with the off-shell structure function shows a clear deviation from the result with the on-shell one. We evaluate also the cross section of semi-inclusive lepton-nucleon proce...
The polarized structure function of the nucleons with a non-extensive statistical quark model
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Instituto de Ciencia, Engenharia e Tecnologia - ICET, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Campus do Mucuri, Rua do Cruzeiro 01, Jardim Sao Paulo, 39803-371, Teofilo Otoni, Minas Gerais (Brazil)
2013-05-06
We studied an application of nonextensive thermodynamics to describe the polarized structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution, often used in the statistical models, were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and the chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon and by {Delta}u and {Delta}d of the polarized functions.
Nucleon spin structure function from the instanton vacuum
International Nuclear Information System (INIS)
We discuss the evaluation of the nucleon isoscalar axial coupling, gA(0), in the instanton vacuum using the 1/NC expansion. This approach allows a fully consistent treatment of the U(1)A anomaly. We compute the nucleon matrix element of the topological charge, , and show that it reduces to the matrix element of the isoscalar axial quark current. Our arguments show that the usual evaluation of gA(0) in the chiral quark soliton model is consistent with the U(1)A anomaly in leading order of 1/NC. Such calculations give gA(0) = 0.36, which is in agreement with the recent estimate by Ellis and Karliner. (author)
Nucleon spin structure function from the instanton vacuum
Energy Technology Data Exchange (ETDEWEB)
Weiss, C. [Inst. fuer Theoretishe Physik 2, Ruhr Univ. Bochum, Bochum (Germany)
1996-06-01
We discuss the evaluation of the nucleon isoscalar axial coupling, g{sub A}{sup (0)}, in the instanton vacuum using the 1/N{sub C} expansion. This approach allows a fully consistent treatment of the U(1){sub A} anomaly. We compute the nucleon matrix element of the topological charge,
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.)
Linear estimates of structure functions from deep inelastic lepton-nucleon scattering data. Part 1
International Nuclear Information System (INIS)
This paper concerns the linear estimation of structure functions from muon(electron)-nucleon scattering. The expressions obtained for the structure functions estimate provide correct analysis of the random error and the bias The bias arises because of the finite number of experimental data and the finite resolution of experiment. The approach suggested may become useful for data handling from experiments at HERA. 9 refs
Study of the spin structure functions of the nucleon: the E143 experiment at SLAC
International Nuclear Information System (INIS)
In this thesis, we present the results of the E143 experiment of deep inelastic scattering of 29 GeV polarized electrons from polarized NH3 and ND3 targets, at SLAC. The goal of the experiment is the measurement of the spin structure functions g1 and g2 of the nucleon which provide information on its internal spin structure. Experimentally, the structure functions are extracted from the measurement of cross section asymmetries. Our measured values of the first moment of g1 are two and three standard deviations below the Ellis-Jaffe sum rule predictions, for the proton and for the deuteron, respectively. The Bjoerken sum rule, a QCD fundamental prediction, has been confirmed. We find the quark contribution to the nucleon spin to be around 30 pc. Our results on g2 are well described by the Wandzura-Wilczek expression. (author)
Target Mass Corrections to QCD Bjorken Sum Rule for Nucleon Spin Structure Functions
Kawamura, Hiroyuki; UEMATSU, Tsuneo
1995-01-01
We discuss the possible target mass corrections in the QCD analysis of nucleon's spin-dependent structure functions measured in the polarized deep-inelastic leptoproduction. The target mass correction for the QCD Bjorken sum rule is obtained from the Nachtmann moment and its magnitude is estimated employing positivity bound as well as the experimental data for the asymmetry parameters. We also study the uncertainty due to target mass effects in determining the QCD effective ...
International Nuclear Information System (INIS)
We present a model description of the nucleon valence structure function applicable over the entire region of the Bjorken variable x, and above moderate values of Q2 (?1 GeV2). We stress the importance of describing the complete spectrum of intermediate states which are spectator to the deep-inelastic collision. At a scale of 1 GeV2 the relevant degrees of freedom are constituent quarks and pions. The large-x region is then described in terms of scattering from constituent quarks in the nucleon, while the dressing of constituent quarks by pions plays an important role at intermediate x values. The correct small-x behavior, which is necessary for the proper normalization of the valence distributions, is guaranteed by modeling the asymptotic spectator mass spectrum according to Regge phenomenology. (orig.)
A two component model describing nucleon structure functions in the low-x region
Energy Technology Data Exchange (ETDEWEB)
Bugaev, E.V. [Institute for Nuclear Research of the Russian Academy of Sciences, 7a, 60th October Anniversary prospect, Moscow 117312 (Russian Federation); Mangazeev, B.V. [Irkutsk State University, 1, Karl Marx Street, Irkutsk 664003 (Russian Federation)
2009-12-15
A two component model describing the electromagnetic nucleon structure functions in the low-x region, based on generalized vector dominance and color dipole approaches is briefly described. The model operates with the mesons of rho-family having the mass spectrum of the form m{sub n}{sup 2}=m{sub r}ho{sup 2}(1+2n) and takes into account the nondiagonal transitions in meson-nucleon scattering. The special cut-off factors are introduced in the model, to exclude the gamma-qq-bar-V transitions in the case of narrow qq-bar-pairs. For the color dipole part of the model the well known FKS-parameterization is used.
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)
Strangeness content and structure function of the nucleon in a statistical quark model
Trevisan, L A; Tomio, L
1999-01-01
The strangeness content of the nucleon is determined from a statistical model using confined quark levels, and is shown to have a good agreement with the corresponding values extracted from experimental data. The quark levels are generated in a Dirac equation that uses a linear confining potential (scalar plus vector). With the requirement that the result for the Gottfried sum rule violation, given by the new muon collaboration (NMC), is well reproduced, we also obtain the difference between the structure functions of the proton and neutron, and the corresponding sea quark contributions. (27 refs).
Nucleon structure functions from dynamical (2+1)-flavor domain wall fermions
Ohta, Shigemi
2008-01-01
We report isovector form factors and low moments of isovector structure functions of nucleon from the coarse RIKEN-BNL-Columbia (RBC) and UKQCD joint dynamical (2+1)-flavor domain-wall fermions (DWF) ensembles. The lattice cut off is estimated at (a^{-1}=1.7) GeV. The lattice volume is as large as 2.7 fm across. We carefully optimize the nucleon source/sink separation in time to about 1.4 fm. Unexpectedly large finite-size effect in the axial charge is found. The effect scales with a single variable, the product (m_\\pi L) of the pion mass (m_\\pi) and lattice spatial linear extent (L), and sets in at around (m_\\pi L = 5). We also discuss momentum-transfer dependence of the vector, induced tensor, axial-vector and induced pesudo-scalar form factors. From structure functions, fully non-perturbatively renormalized iso-vector quark momentum fraction, (_{u-d}), helicity fraction, (_{\\Delta u - \\Delta d}), and transversity, (_{\\delta u - \\delta d}), are reported, as well as an unrenormalized twist-3 coefficient, (d_...
A detailed study of nucleon structure function in nuclei in the valence quark region
Energy Technology Data Exchange (ETDEWEB)
Bianchi, N. [INFN-Laboratori, Nazionali di Frascati (Italy)
1994-04-01
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.
International Nuclear Information System (INIS)
Data are presented on the spin-dependent structure function of the proton, gp1, measured in inclusive polarized muon scattering. The first moment of gp1(x) is compared with that of earlier experiments and with the Ellis-Jaffe prediction. Also semi-inclusive data are shown, where charged hadrons provide information on spin-flavor correlations. In the context of the quark-parton model the data indicate that quark spins contribute a small fraction to the nucleon spin. All published data of g1 in combination confirm the Bjorken sum rule at the 10 percent accuracy level. In a QCD analysis of Fp2 and Fd2, measured with high precision down to small x by NMC, the gluon distribution is determined. The Fn2/Fp2 data are reanalyzed and the Gottfried sum ?10[Fp2(x)-Fn2(x)]/x dx is evaluated. The earlier reported flavor asymmetry in the nucleon is confirmed. copyright 1995 American Institute of Physics
Modelling the nucleon structure
Burkardt, M
2015-01-01
We review the status of our understanding of nucleon structure based on the modelling of different kinds of parton distributions. We use the concept of generalized transverse momentum dependent parton distributions and Wigner distributions, which combine the features of transverse-momentum dependent parton distributions and generalized parton distributions. We revisit various quark models which account for different aspects of these parton distributions. We then identify applications of these distributions to gain a simple interpretation of key properties of the quark and gluon dynamics in the nucleon.
Nucleon isovector structure functions in (2+1)-flavor QCD with domain wall fermions
Aoki, Yasumichi; Lin, Huey-Wen; Ohta, Shigemi; Sasaki, Shoichi; Tweedie, Robert; Yamazaki, Takeshi; Zanotti, James
2010-01-01
We report on numerical lattice QCD calculations of some of the low moments of the nucleon structure functions. The calculations are carried out with gauge configurations generated by the RBC and UKQCD collaborations with (2+1)-flavors of dynamical domain wall fermions and the Iwasaki gauge action ($\\beta = 2.13$). The inverse lattice spacing is $a^{-1} = 1.73$ GeV, and two spatial volumes of ((2.7{\\rm fm})^3) and ((1.8 {\\rm fm})^3) are used. The up and down quark masses are varied so the pion mass lies between 0.33 and 0.67 GeV while the strange mass is about 12 % heavier than the physical one. The structure function moments we present include fully non-perturbatively renormalized iso-vector quark momentum fraction, (_{u-d}), helicity fraction, (_{\\Delta u - \\Delta d}), and transversity, (_{\\delta u - \\delta d}), as well as an unrenormalized twist-3 coefficient, (d_1). The ratio of the momentum to helicity fractions, (_{u-d}/_{\\Delta u - \\Delta d}), does not show dependence on the light quark mass and agrees ...
Study of the nucleon spin structure functions: the E154 experiment at SLAC
International Nuclear Information System (INIS)
In experiment E154 at SLAC, the spin dependent structure function g1n was measured by scattering longitudinally polarized 50 GeV electrons off a longitudinally polarized helium 3 target. We report the integral over the measured x range to be ?0.0140.7g1n(x,5 GeV2)dx = -0.0348 ± 0.0033 ± 0.0043 ± 0.0014. We observe relatively large values of g1n at low x, calling into question the reliability of the data extrapolation down to x equal 0. Such a divergent behavior seems to disagree with the prediction of the Regge theory but can be quantitatively explained by perturbative QCD. Moreover, we have performed a NLO perturbative QCD analysis of the world data on g1, paying careful attention to both the theoretical hypothesis and the calculation of errors. Using a parametrization of the polarized parton distribution at a low scale, we can access the fraction of spin carried by quarks: ?? = 29 ± 6 pc in the MS-bar scheme, and ?? = 37 ± 7 pc in the AB scheme. The gluon contribution to the nucleon spin is not well enough constrained by the current data, but seems to lie between 0 and 2. This study allows us to extract the first moment of the g1 structure function and we find agreement with the Bjorken sum rule expectations. (author)
Indian Academy of Sciences (India)
N Barik; R N Mishra
2001-04-01
Considering the nucleon as consisting entirely of its valence quarks con?ned independently in a scalar-vector harmonic potential; unpolarized structure functions $F_{1}(x,\\mu^{2})$ and $F_{2}(x,\\mu^{2})$ are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions $u_{v}(x,\\mu^{2})$ and $d_{v}(x,\\mu^{2})$ are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of $\\mu^{2}=0.07$ GeV2 to a higher $Q^{2}$ scale of $Q^{2}_{0} = 15$ GeV2 yields $xu_{v}(x, Q^{2}_{0})$ and $xd_{v}(x, Q^{2}_{0})$ in good agreement with experimental data. The gluon and sea-quark distributions such as $G(x,Q^{2}_{0})$ and $q_{s}(x, Q^{2}_{0})$ are dynamically generated with a reasonable qualitative agreement with the available data; using the leading order renormalization group equations with appropriate valence-quark distributions as the input.
Nucleon structure from lattice QCD
International Nuclear Information System (INIS)
In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a2) discretization effects.
Nucleon structure from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Dinter, Simon
2012-11-13
In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a{sup 2}) discretization effects.
Nucleon structure using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, C.; Kallidonis, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Constantinou, M.; Hatziyiannakou, K. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Drach, V. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Jansen, K. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Koutsou, G.; Vaquero, A. [The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Leontiou, T. [Frederick Univ, Nicosia (Cyprus). General Dept.
2013-03-15
A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distribution are discussed, assessing the methods applied for their study, including approaches to evaluate the disconnected contributions. Results on the spin carried by the quarks in the nucleon are also presented.
Nucleon structure functions from dynamical (2+1)-flavor domain wall fermions
Ohta, Shigemi
2009-01-01
We report lattice-volume independence of low moments of nucleon structure functions from the coarse RIKEN-BNL-Columbia (RBC) and UKQCD joint dynamical (2+1)-flavor domain-wall fermions (DWF) ensembles at the lattice cut off of (a^{-1}\\sim1.7) GeV. The isovector quark momentum fraction, (_{u-d}), and helicity fraction, (_{\\Delta u - \\Delta d}), both fully non-perturbatively renormalized are studied on two spatial volumes of ((\\sim {\\rm 2.7 fm})^3) and ((\\sim {\\rm 1.8 fm})^3). Their naturally renormalized ratio, (_{u-d}/_{\\Delta u - \\Delta d}), is not affected by any finite-size effect. It does not depend strongly on light quark mass and does agree well with the experiment. The respective absolute values, fully non-perturbatively renormalized, do not show any finite-size effect either. They show trending toward the respective experimental values at the lightest up- and down-quark mass. This trending down to the experimental values appears to be a real physical effect driven by lighter quarks. The observations a...
Watanabe, Akira; Suzuki, Katsuhiko
2014-06-01
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.
Nucleon structure functions at small $x$ via the Pomeron exchange in AdS space with a soft IR wall
Watanabe, Akira
2013-01-01
We present analyses on nucleon structure functions at the 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 AdS geometry is smoothly cut off at IR. Combining the improved Pomeron-nucleon coupling and the wave function of the 5D U(1) vector field with the BPST Pomeron exchange kernel, then we obtain the structure functions. Here we focus on the nonperturbative kinematical region, where $10^{-6} \\leq x \\leq 10^{-2}$ and $0.1 \\leq Q^2 \\leq 10$ [GeV$^2$], and show that our calculations for $F_2^p$ and $F_L^p$ 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, $F_L^p/F_T^p$, depends on both of $x$ and $Q^2$.
Nucleon Structure from Lattice QCD
Richards, David
2007-01-01
Recent advances in lattice field theory, in computer technology and in chiral perturbation theory have enabled lattice QCD to emerge as a powerful quantitative tool in understanding hadron structure. I describe recent progress in the computation of the nucleon form factors and moments of parton distribution functions, before proceeding to describe lattice studies of the Generalized Parton Distributions (GPDs). In particular, I show how lattice studies of GPDs contribute to building a three-dimensional picture of the proton. I conclude by describing the prospects for studying the structure of resonances from lattice QCD.
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
Probing Nucleon Spin Structure
Ramsey, G P
1997-01-01
One of the important questions in high energy physics is the relation of quark and gluon spin to that of the nucleons which they comprise. Polarization experiments provide a mechanism to probe the spin properties of elementary particles and provide crucial tests of Quantum Chromodynamics (QCD). The theoretical and experimental status of this fundamental question will be reviewed in this paper.
Directory of Open Access Journals (Sweden)
E.R. Nocera
2015-03-01
Full Text Available 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 most of the available experimental information, and are determined with a minimally biased methodology, these are especially suited for such a study. I show how NNPDFpol1.1 can discriminate between different theoretical models, even though NNPDF uncertainties remain large near the endpoints x?0 and x?1, due to the lack of experimental information. I discuss how our knowledge of nucleon spin structure may be improved at small x by future measurements at an Electron–Ion Collider, and at large x by recent measurements at Jefferson Lab, also in view of its 12 GeV upgrade.
Nocera, Emanuele Roberto
2014-01-01
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 most of the available experimental information, and are determined with a minimally biased methodology, these are especially suited for such a study. I show how NNPDFpol1.1 can discriminate between different theoretical models, even though NNPDF uncertainties remain large near the endpoints $x\\to 0$ and $x\\to 1$, due to the lack of experimental information. I discuss how our knowledge of nucleon spin structure may be improved at small-$x$ by future measurements at an Electron-Ion Collider, and at large-$x$ by recent measurements at Jefferson...
Nucleon structure from stochastic estimators
Energy Technology Data Exchange (ETDEWEB)
Najjar, Johannes Siegfried Samir
2014-10-01
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
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
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.)
Generalized sum rules for spin-dependent structure functions of the nucleon
International Nuclear Information System (INIS)
The Drell-Hearn-Gerasimov and Bjorken sum rules are special examples of dispersive sum rules for the spin-dependent structure function G1(?,Q2) at Q2=0 and ?. We generalize these sum rules through studying the virtual-photon Compton amplitudes S1(?,Q2) and S2(?,Q2). At small Q2, we calculate the Compton amplitudes at leading order in chiral perturbation theory; the resulting sum rules will be able to be tested against data soon available from the Jefferson Laboratory. For Q2>>?QCD2, the standard twist-expansion for the Compton amplitudes leads to the well known deep-inelastic sum rules. Although the situation is still relatively unclear in a small intermediate-Q2 window, we argue that chiral perturbation theory and the twist-expansion alone already provide strong constraints on the Q2-evolution of the G1(?,Q2) sum rule from Q2=0 to ?. (author)
Nucleon form factors and structure functions with N_f=2+1 dynamical domain wall fermions
Yamazaki, T
2007-01-01
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...
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
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.
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
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.)
Ziaja, Beata
2002-01-01
Theoretical predictions show that at low values of Bjorken $x$ the spin structure function, $g_1$ is influenced by large logarithmic corrections, $ln^2(1/x)$, which may be predominant in this region. These corrections are also partially contained in the NLO part of the standard DGLAP evolution. Here we calculate the non-singlet component of the nucleon structure function, $g_1^{NS}=g_1^p-g_1^n$, and its first moment, using a unified evolution equation. This equation incorpor...
Nucleon spin structure functions
International Nuclear Information System (INIS)
There has been recent excitement arising from the claim by the EMC collaboration that none of the proton's spin is carried by quarks. There are many textbooks, including those written by some members of this audience which assert that the proton's spin is carried by quarks. I will review the history of deep inelastic scattering of polarized leptons from polarized protons, culminating in this most recent dramatic claim. I will show that, for the last decade, data have appeared consistent with predictions of the quark model and highlight what the new and potentially exciting data are. I will conclude with suggestions for the future, and discuss the polarization dependence of inclusive hadron production. 35 refs
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
Short-range correlations of partons & 3D nucleon structure
Directory of Open Access Journals (Sweden)
Schweitzer P.
2014-03-01
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.
International Nuclear Information System (INIS)
Various aspects of nuclear physics at intermediate energies, in connection with the description of the nucleon-nucleon potential in terms of mesons, are presented in this thesis. The meson exchange current contribution is studied in the case of the deuteron (np capture and electrodisintegration near threshold). A consistent description of these processes is discussed, with particular emphasis on the effective range of the current, for momentum transfers as large as q2?1 (GeV/c)2. The structure of finite nuclei and nuclear matter is then analysed in the framework of a relativistic formalism, in which the negative energy component of the nucleon wave function is explicitly taken into account. The nuclear matter saturation mechanism is studied in details and compared with the non-relativistic limit. Properties of finite nuclei are also discussed. Finally, the structure of the nucleon itself in the nuclear medium is investigated. A connection between the polarisation of the nucleon (three valence quark component), the incompressibility parameter and the mass of the first monopole excitation of the nucleon is presented
Energy Technology Data Exchange (ETDEWEB)
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
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.
Experimental Study of Nucleon Structure and QCD
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen
2012-03-01
Overview of Experimental Study of Nucleon Structure and QCD, with focus on the spin structure. Nucleon (spin) Structure provides valuable information on QCD dynamics. A decade of experiments from JLab yields these exciting results: (1) valence spin structure, duality; (2) spin sum rules and polarizabilities; (3) precision measurements of g{sub 2} - high-twist; and (4) first neutron transverse spin results - Collins/Sivers/A{sub LT}. There is a bright future as the 12 GeV Upgrade will greatly enhance our capability: (1) Precision determination of the valence quark spin structure flavor separation; and (2) Precision extraction of transversity/tensor charge/TMDs.
Transverse Spin Structure of the Nucleon
Perdekamp, Matthias Grosse
2015-01-01
We review the current status and future perspectives of theory and experiments of transverse spin phenomena in high-energy scattering processes off nucleon targets and related issues in nucleon structure and QCD. Systematic exploration of transverse spin effects requires measurements in polarized deep-inelastic scattering, polarized pp collisions, and e+e- annihilations. Sophisticated QCD-based techniques are also needed to analyze the experimental data sets.
International Nuclear Information System (INIS)
Polarized deep inelastic lepton-nucleon scattering is an important tool to study the spin structure of the nucleon. In 1988, the European Muon Collaboration (EMC) experiment which used a polarized muon beam at CERN reported a surprising result on the contribution of quarks to the proton spin; the proton spin may not be carried by quarks. Later this was referred as a 'Spin Crisis'. Furthermore the EMC results indicated that the strange quark is polarized oppositely with respect to the proton spin and the violation of the Ellis-Jaffe sum rule was pointed. Since the EMC results appeared, many theoretical and experimental efforts have been made to explain this. Theoretical efforts have been paid to understand the spin dependent structure function in the framework of QCD. Spin dependent QCD evolution equations were calculated up to Next-to-Leading Order of the strong coupling constant, ?s, and that made the NLO QCD analysis of the structure functions possible. Many polarized DIS experiments, Spin Muon Collaboration (SMC) at CERN, E142, E143, E154 and E155 at SLAC and the HERMES collaboration at DESY, have been providing experimental data. Each experiment covers complementary kinematic regions. They provide widely spread experimental data of the structure functions in the kinematic region, and it thus became possible to study the QCD evolution of the structure functions experimentally. In particular the SMC experiment is able to access the lowest x and highest Q2, hence reducing one of the largest uncertainties, the low x extrapolation. This paper presents the results of spin dependent structure functions for proton and deuteron obtained by the SMC experiment from 1992 to 1996. The resulting values of 1st moment of g1p,d,n at 5 GeV2 based on all available experimental data are also presented with the results of the NLO QCD analysis of structure functions done in SMC. The Bjorken sum rule, which is the fundamental relation in QCD, is tested in independent QCD analysis. (author)
Nucleon spin structure at low momentum transfers
Pasechnik, Roman; Teryaev, Oleg
2010-01-01
The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into account higher order radiative and higher twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent proton structure function $\\Gamma_1^{p}(Q^2)$ and on the Bjorken sum rule $\\Gamma_1^{p-n}(Q^2)$. By using the singularity-free analytic perturbation theory we demonstrate that the matching point between chiral-like positive-$Q^2$ expansion and QCD operator product $1/Q^2$-expansion for the nucleon spin sum rules can be shifted down to rather low $Q\\simeq\\Lambda_{QCD}$ leading to a good description of recent proton, neutron, deuteron and Bjorken sum rule data at all accessible $Q^2$.
New insights into the spin structure of the nucleon
Bernard, V; Krebs, H; Meißner, U -G
2012-01-01
We analyze the low-energy spin structure of the nucleon in a covariant effective field theory with explicit spin-3/2 degrees of freedom to third order in the small scale expansion. Using the available data on the strong and electromagnetic width of the Delta-resonance, we give parameter-free predictions for various spin-polarizabilities and moments of spin structure functions. We find an improved description of the nucleon spin structure at finite photon virtualities for some observables and point out the necessity of a fourth order calculation.
The spin structure of the nucleon
International Nuclear Information System (INIS)
This document describes the recent experimental results on the spin structure of the nucleon obtained with the electron accelerator Thomas Jefferson National Facility (Jefferson Lab), Virginia. We first discuss the goal of studying the nucleon spin structure and give the basis and phenomenology of high energy lepton scattering. Then, we discuss with some details a few sum rules concerning the spin structure of the nucleon. Those are important tools for studying the nucleon spin structure at Jefferson Lab. We then describe the present experimental situation and analyze the results. We have been able to determine an effective coupling constant for the strong interaction for any regime of quantum chromodynamics which proves that QCD is an approximately conformal theory. We conclude on the perspectives for this field of research, in particular with the 12 GeV energy upgrade of Jefferson Lab. The top priority will be the measurement of generalised parton distributions. The only issue that will stay misunderstood is the role of the very low x domain on the spin structure of the nucleon
Meson-cloud effects in the electromagnetic nucleon structure
Kupelwieser, Daniel
2013-01-01
We study how the electromagnetic structure of the nucleon is influenced by a pion cloud. To this aim we make use of a constituent-quark model with instantaneous confinement and a pion that couples directly to the quarks. To derive the invariant 1- photon-exchange electron-nucleon scattering amplitude we employ a Poincar\\'e- invariant coupled-channel formulation which is based on the point-form of relativistic quantum mechanics. We argue that the electromagnetic nucleon current extracted from this amplitude can be reexpressed in terms of pure hadronic degrees of freedom with the quark substructure of the pion and the nucleon being encoded in electromagnetic and strong vertex form factors. These are form factors of bare particles, i.e. eigenstates of the pure confinement problem. First numerical results for (bare) photon-nucleon and pion-nucleon form factors, which are the basic ingredients of the further calculation, are given for a simple 3-quark wave function of the nucleon.
A covariant model for the nucleon spin structure
Ramalho, G
2015-01-01
We present the results of the covariant spectator quark model applied to the nucleon structure function $f(x)$ measured in unpolarized deep inelastic scattering, and the structure functions $g_1(x)$ and $g_2(x)$ measured in deep inelastic scattering using polarized beams and targets ($x$ is the Bjorken scaling variable). The nucleon is modeled by a valence quark-diquark structure with $S,P$ and $D$ components. The shape of the wave functions and the relative strength of each component are fixed by making fits to the deep inelastic scattering data for the structure functions $f(x)$ and $g_1(x)$. The model is then used to make predictions on the function $g_2(x)$ for the proton and neutron.
Nucleon spin structure studies at COMPASS
International Nuclear Information System (INIS)
One of the main goal of the COMPASS experiment at CERN is the study of the spin structure of the nucleon in DIS, by scattering 160 GeV polarized muon beam on a longitudinally (or transversely) polarized 6LiD target. Besides the scattered muon, the particles produced in the deep inelastic scattering are detected by a two stage magnetic spectrometer equipped with state of the art tracking and particle ID detectors. The emphasis of COMPASS muon program is the direct determination of the gluon polarization ?G/G, accessed via asymmetries involving photon-gluon fusion mechanism (PGF). Both open charm production (detecting D0,s), as well as production of high ?T hadron pairs are used to tag PGF. Preliminary results for ?G/G based on the analysis of 2002 and 2003 data are shown. In addition, improved measurement of the deuteron structure function g1d at small x, as well as studies of transverse distribution functions in the deuteron by measuring Collins and Sivers azimuthal asymmetries, are reported. (author)
Ma, Y G; Shen, W Q; Cai, X Z; Chen, J G; Chen, J H; Fang, D Q; Guo, W; Ma, C W; Ma, G L; Su, Q M; Tian, W D; Wang, K; Yan, T Z; Zhong, C; Zuo, J X
2006-01-01
Momentum correlation functions of the nucleon-nucleon pairs are presented for reactions with C isotopes bombarding a $^{12} \\rm C$ target within the framework of the isospin-dependent quantum molecular dynamics model. The binding-energy dependence of the momentum correlation functions is also explored, and other factors that have an influence on momentum correlation functions are investigated. These factors include momentum-dependent nuclear equation of state, in-medium nucleon-nucleon cross sections, impact parameters, total pair momenta, and beam energy. In particular, the rise and the fall of the strength of momentum correlation functions at lower relative momentum are shown with an increase in beam energy.
Relativistic Deuteron Structure Function
Melnitchouk, W; Schreiber, A. W.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
1994-01-01
We calculate the unpolarised deep inelastic structure function of a relativistic deuteron within a covariant framework. An exact treatment of nucleon off-shell effects is shown to give corrections to the widely-used convolution model, even in impulse approximation. Neglecting off-shell effects in the extraction of the neutron structure function from deuterium data introduces errors of order $1-2\\%$.
Nucleon structure and the chiral filter
International Nuclear Information System (INIS)
I discuss the issues of quenched gA in nuclei, pionic enhancement of nuclear electromagnetic form factors, manifestation of the anomalous Wess-Zumino term in nuclear medium, all on the same footing, in terms of the nucleon structure as 'derived' from a low-energy effective theory of QCD
Nucleon Spin Structure: Longitudinal and Transverse
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen
2011-02-01
Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction. The transverse spin structure and the TMDs are the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has played a major role in the worldwide effort to study both the longitudinal and transverse spin structure. Highlights of recent results will be presented. With 12-GeV energy upgrade, JLab will provide the most precise measurements in the valence quark region to close a chapter in longitudinal spin study. JLab will also perform a multi-dimensional mapping of the transverse spin structure and TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space and extracting the u and d quark tensor charges of the nucleon. The precision mapping of TMDs will also allow a detailed study of the quark orbital motion and its dynamics.
Nucleon structure study by virtual Compton scattering
International Nuclear Information System (INIS)
It is proposed to study nucleon structure by virtual Compton scattering using the Hall A HRS spectrometers. This reaction is planned to be measured in the Roper resonance region and at the highest center of mass energy to observe the beginning of the hard scattering regime. (author) 25 refs.; 8 figs.; 6 tabs
Physicis of Q2-dependence in the nucleon's G1(x,Q2) structure function sum rule
International Nuclear Information System (INIS)
I discuss in this talk the physics of the Q2 dependence of the Gl(x,Q2) structure function sum rule. For Q2 > 3 GeV2, the Q2 variation is controlled by pure QCD radiative corrections. For 0.5 2 2, the twist-four contribution becomes significant, but stays perturbative. For Q2 below ? 0.05, the sum rule is determined by low-energy theorems. The rapid change of the sum rule between 0.05 and 0.5 GeV2 signals the transition between parton and hadron degrees of freedom
Non-perturbative structure of the polarized nucleon sea
Cao, Fu-Guang; Signal, A. I.
2003-01-01
We investigate the flavour and quark-antiquark structure of the polarized nucleon by calculating the parton distribution functions of the nucleon sea using the meson cloud model. We find that the SU(2) flavor symmetry in the light antiquark sea and quark-antiquark symmetry in the strange quark sea are broken, {\\it i.e.} $\\Delta\\ubar < \\Delta \\dbar$ and $\\Delta s < \\Delta \\sbar$. The polarization of the strange sea is found to be positive, which is in contradiction to previou...
Transverse nucleon structure and multiparton interactions
Strikman, Mark
2011-01-01
The transverse structure of the nucleon as probed in hard exclusive processes plays critical role in the understanding of the structure of the underlying event in hard collisions at the LHC, and multiparton interactions. We summarize results of our recent studies of manifestation of transverse nucleon structure in the hard collisions at the LHC, new generalized parton distributions involved in multiparton interactions, presence of parton fluctuations. The kinematic range where interaction of fast partons of the projectile with the target reach black disk regime (BDR) strength is estimated. We demonstrate that in the BDR postselection effect leads to effective fractional energy losses. This effect explains regularities of the single and double forward pion production in $ dAu$ collisions at RHIC and impacts on the forward physics in $pp$ collisions at the LHC.
Structure and Spin of the Nucleon
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut A. [JLAB
2014-03-01
Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
The nucleon spin structure in a simple quark model
Ma, B Q; Yang Jian Jun; Ma, Bo-Qiang; Schmidt, Ivan; Yang, Jian-Jun
2000-01-01
We investigate the spin structure of the nucleon in an extended Jaffe-Lipkin quark model. In addition to the conventional $3q$ structure, different $(3q)(Q\\bar{Q})$ admixtures in the nucleon wavefunction are also taken into account. The contributions to the nucleon spin from various components of the nucleon wavefunction are discussed. The effect due to the Melosh-Wigner rotation is also studied.
Di-hadron fragmentation and mapping of the nucleon structure
Pisano, Silvia
2015-01-01
The fragmentation of a colored parton directly into a pair of colorless hadrons is a non-perturbative mechanism that offers important insights into the nucleon structure. Di-hadron fragmentation functions can be extracted from semi-inclusive electron-positron annihilation data. They also appear in observables describing the semi-inclusive production of two hadrons in deep-inelastic scattering of leptons off nucleons or in hadron-hadron collisions. When a target nucleon is transversely polarized, a specific chiral-odd di-hadron fragmentation function can be used as the analyzer of the net density of transversely polarized quarks in a transversely polarized nucleon, the so-called transversity distribution. The latter can be extracted through suitable single-spin asymmetries in the framework of collinear factorization, thus in a much simpler framework with respect to the traditional one in single-hadron fragmentation. At subleading twist, the same chiral-odd di-hadron fragmentation function provides the cleanest...
Energy Technology Data Exchange (ETDEWEB)
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
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.
Ma*, Y. G.; Wei, Y. B.; Shen, W.Q.(Shanghai Institute of Applied Physics, Shanghai, 201800, China); Cai, X. Z.; J. G. Chen; Chen, J H; Fang, D. Q.; W. Guo; Ma, C. W.; Ma, G. L.; Su, Q. M.; Tian, W. D.(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800, Shanghai, China); Wang, K.; Yan, T. Z.; Zhong, C.
2006-01-01
Momentum correlation functions of the nucleon-nucleon pairs are presented for reactions with C isotopes bombarding a $^{12} \\rm C$ target within the framework of the isospin-dependent quantum molecular dynamics model. The binding-energy dependence of the momentum correlation functions is also explored, and other factors that have an influence on momentum correlation functions are investigated. These factors include momentum-dependent nuclear equation of state, in-medium nucl...
Electromagnetic studies of nucleon and nuclear structure
International Nuclear Information System (INIS)
Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on 12C and 16O are reported, as well as work on nuclear structure models and instrumentation development
International Nuclear Information System (INIS)
I show that the recent precise data on the Nachtmann moments M(n,Q2) from Q2 = 3 to 40 (GeV/c)2 are extremely well represented by straight lines in the variable 1/Q2 indicating M(n,Q2) approx. equal to A0(n) + A1(n)/Q2. The threshold behaviour of the scaling function F2(x) obtained from the above ansatz, is in excellent agreement with the Drell-Yan-West relation. The predictions for M(n,Q2) for values of Q2 larger than about 200 (GeV/c)2 are quite distinct from QCD-expectations. (orig.)
Nucleon structure and properties of dense matter
International Nuclear Information System (INIS)
We consider the properties of dense matter in a framework of the Skyrme soliton model and the chiral bag model. The influence of the nucleon structure on the equation of state of dense matter is emphasized. We find that in both models the energy per unit volume is proportional to n4/3, n being the baryon number density. We discuss the properties of neutron stars with a derived equation of state. The role of many-body effects is investigated. The effect of including higher order terms in the chiral lagrangian is examined. The phase transition to quark matter is studied. 29 refs., 6 figs. (author)
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
Nucleon wave function from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Warkentin, Nikolaus
2008-04-15
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
Nucleon wave function from lattice QCD
International Nuclear Information System (INIS)
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
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
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)
Vector resonances and electromagnetic nucleon structure
International Nuclear Information System (INIS)
Motivated by new, precise magnetic proton form factor data in the timelike reigon, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson rsonances on electromagnetic nucleon structure. We find that the ?(1700), ?(1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the p bar p threshold. We also investigate sensitivity to the ? meson. The model dependence of our result is tested by introducing an alternative model which couples the isoscalar vector meson states to a hypothetical vector glueball resonance. We obtain nearly identical results from both models, except for GEn(q2) in the spacelike region which is very sensitive to the glueball mass and the effective ?NN coupling
The pion-cloud contribution to the electromagnetic nucleon structure
Kupelwieser, D
2015-01-01
The present contribution continues and extends foregoing work on the calculation of electroweak form factors of hadrons using the point-form of relativistic quantum mechanics. Here we are particularly interested in studying pionic effects on the electromagnetic structure of the nucleon. To this aim we employ a hybrid constituent-quark model that comprises, in addition to the $3q$ valence component, also a $3q$+$\\pi$ non-valence component. With a simple wave function for the $3q$ component we get reasonable results for the nucleon form factors. In accordance with other authors we find that the pionic effect is significant only below $Q^2\\lesssim 0.5$~GeV$^2$.
The phase-functions method and full cross-section of nucleon-nucleon scattering
Zhaba, V I
2016-01-01
For calculation of the single-channel nucleon-nucleon scattering a phase-functions method has been considered. Using a phase-functions method the following phase shifts of a nucleon-nucleon scattering are calculated numerically: nn (1S0-, 3P0-, 3P1-, 1D2-, 3F3- state), pp (1S0-, 3P0-, 3P1-, 1D2- state) and np (1S0-, 1P1-, 3P0-, 3P1-, 1D2-, 3D2- state). The calculations has been performed using realistic nucleon-nucleon potentials Nijmegen groups (NijmI, NijmII, Reid93) and potential Argonne v18. Obtained phase shifts are in good agreement with the results obtained in the framework of other methods. Using the obtained phase shifts we have calculated the full cross-section. Our results are in good agreement with those obtained by using known phases published in literature. The odds between calculations depending on a computational method of phases of scattering makes: 0,2-6,3% for pp- and 0,1-5,3% for np- scatterings (NijmI, NijmII), 0,1-4,1% for pp- and 0,1-0,4% for np- scatterings (Reid93), no more than 4,5% ...
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)
Structure and spin of the nucleon
Directory of Open Access Journals (Sweden)
Avakian H.
2014-03-01
Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL. TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC, FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Shu, Zhan; Chen, Xiao-Lin; Deng, Wei-Zhen
2007-01-01
In $\\XQM$, a quark can emit Goldstone bosons. The flavor symmetry breaking in the Goldstone boson emission process is used to intepret the nucleon flavor-spin structure. In this paper, we study the inner structure of constituent quarks implied in $\\XQM$ caused by the Goldstone boson emission process in nucleon. From a simplified model Hamiltonian derived from $\\XQM$, the intrinsic wave functions of constituent quarks are determined. Then the obtained transition probabilities...
The Structure of the Nucleon: Elastic Electromagnetic Form Factors
Punjabi, V; Jones, M K; Brash, E J; Carlson, C E
2015-01-01
Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. Accurate experimental measurements of the nucleon form factors are a test-bed for understanding how the nucleon's static properties and dynamical behavior emerge from QCD, the theory of the strong interactions between quarks. There has been enormous theoretical progress, since the publication of the Jefferson Lab proton form factor ratio data, aiming at reevaluating the picture of the nucleon. We will review the experimental and theoretical developments in this field and discuss the outlook for the future.
The structure of the nucleon: Elastic electromagnetic form factors
International Nuclear Information System (INIS)
Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. Accurate experimental measurements of the nucleon form factors are a test-bed for understanding how the nucleon's static properties and dynamical behavior emerge from QCD, the theory of the strong interactions between quarks. There has been enormous theoretical progress, since the publication of the Jefferson Lab proton form factor ratio data, aiming at reevaluating the picture of the nucleon. We will review the experimental and theoretical developments in this field and discuss the outlook for the future. (orig.)
Nucleon spin structure I: A dynamical determination of gluon helicity distribution in the nucleon
Zhu, Wei
2015-01-01
Gluon helicity distribution in the nucleon is dynamically predicted by using a nonlinear QCD evolution equation-the DGLAP equation with the parton recombination corrections - starting from a low scale, where the nucleon is almost only consisted of valence quarks. The comparisons of our predicted gluon helicity distribution with the available data are presented. We find that the contribution of the gluon helicity to the nucleon spin structure is much larger than the predictions of most other theories. This result suggests a significant orbital angular momentum of the gluons is required to balance the gluon helicity. A novel spin-orbital structure of the proton in the light-cone frame is described based on the quantitative calculations,and the nucleon spin crisis is discussed.
Shell structures in oxygen isotopes described with modern nucleon-nucleon interactions
Fujii, S.; Okamoto, R.; Suzuki, K
2003-01-01
Shell structures in the N\\simeq Z nucleus ^{17}O and the neutron-rich oxygen isotopes ^{23}O and ^{25}O are microscopically described by calculating single-particle energies with modern nucleon-nucleon interactions within the framework of the unitary-model-operator approach. It is found that the effect of three-body cluster terms on the single-particle energy is more important in ^{23}O and ^{25}O than ^{17}O.
Study of excited nucleons and their structure
Energy Technology Data Exchange (ETDEWEB)
Burkert, Volker D. [JLAB, Newport News, VA (United States)
2014-01-01
Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.
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
Nucleon spin structure at low momentum transfers
Pasechnik, Roman; Soffer, Jacques; Teryaev, Oleg,
2010-01-01
The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into account higher order radiative and higher twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent proton structure function $\\Gamma_1^{p}(Q^2)$ and on the Bjorken sum rule $\\Gamma_1^{p-n}(Q...
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.)
Nuclear structure functions and QCD
International Nuclear Information System (INIS)
It is shown that QCD evolution equations lead, for high-Q2 nuclear structure functions, to a convolution form with additional collective quark and gluon seas. Classes of models are confronted with this point of view, and it is shown that none of the nucleon models seems satisfactory and the presence of multiquark states seems unavoidable even in the region of x < 1
Wakamatsu, Masashi
2014-01-01
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...
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.)
The spin structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Le Goff, J.M
2005-02-15
The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*{delta}{sigma} + {delta}g + L{sub q} + L{sub g} where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and L{sub q} and L{sub g} are the orbital momentum of the quark and the gluon respectively. The {delta}{sigma} contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization {delta}g/g and the so-called transversity. (A.C.)
International Nuclear Information System (INIS)
This report covers many aspects and some of the singular events which occurred over a two year period (November 1975-November 1977) in the field of nucleonics. Tables (I-IV) include listings of new books, reviews, bibliographies, and conference proceedings. Table III, (the list of conference proceedings) is not as complete as the authors had wished because of the often-experienced long delay time between oral presentation and proceedings publication; therefore, some of the publication dates were not available. By referring to these tables, however, one can find information on almost any facet of nucleonics. According to the authors, their brief written summary emphasizes only the new, interesting, or occasionally, the peculiar aspects of the subject. Discussed are developments in radiation detectors, radiotracer techniques, nuclear archeology, growth in application of activation analysis, decay rate perturbations, and environmental concerns. 213 references
Delineating the polarized and unpolarized partonic structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Jimenez-Delgado, Pedro [JLAB
2015-03-01
Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.
Delineating the polarized and unpolarized partonic structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Jimenez-Delgado, Pedro [JLAB
2015-03-01
Our latest results on the extraction of parton distribution functions of the nucleon are reported. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are given, including a careful treatment of hadronic and nuclear corrections, as well as results on the impact of present and future data in our understanding of the spin of the nucleon.
About Anomalous Magnetic Moment and Structure of Nucleon
Kopylov, A V
1999-01-01
The comparison of magnetic moments of neutron and proton enables to outline qualitatively the structure of nucleon by using a model similar to the one suggested by Ida and Kobayashi that "baryons consist of a qq pair (or diquark) and another quark moving around it with orbital angular momentum L"
About Anomalous Magnetic Moment and Structure of Nucleon
Kopylov, A. V.
1999-01-01
The comparison of magnetic moment of neutron and proton enables to outline qualitatively the structure of nucleon by using a model similar to the one suggested by Ida and Kobayashi that "baryons consist of a qq pair (or a diquark) and another quark moving around it with orbital angular momentum L".
The spin structure of the nucleon: A phenomenological introduction
Bradamante, F
2012-01-01
The investigation of the spin structure of the nucleon via semi-inclusive deep inelastic scattering on polarized nucleons is updated with the most recent results of the JLab, HERMES, and COMPASS experiments. A short description is given of these experiments, which are complementary in phase space and use sophisticated and different techniques to polarize the nucleon targets. The cases of target spin parallel or orthogonal to the direction of the incoming lepton require different experimental techniques, have a different phenomenology and need a different theoretical treatment. After reviewing these differences, the most recent transverse spin advances are presented, and evidence is given that the new data already allow for a rather precise extraction of the transversity and of the Sivers PDFs.
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)
Chiral Symmetry and the Intrinsic Structure of the Nucleon
Leinweber, D. B.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia); Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale, CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA, 5005, Australia)
2001-01-01
Understanding hadron structure within the framework of QCD is an extremely challenging problem. In order to solve it, it is vital that our thinking should be guided by the best available insight. Our purpose here is to explain the model independent consequences of the approximate chiral symmetry of QCD for two famous results concerning the structure of the nucleon. We show that both the apparent success of the constituent quark model in reproducing the ratio of the proton to...
On Electroweak Moments of Baryons and Spin-Flavour Structure of the Nucleon
Gerasimov, S B
1997-01-01
The phenomenological sum-rule-based approach is used to discuss the quark composition dependence of some static and quasi-static electroweak characteristics of nucleons.The role of nonvalence degrees of freedom, the nucleon sea partons and/or peripheral meson currents, is shown to be important to select and make use of the relevant symmetry parametrization of hadron observables. With our preferable universal value of the SU(3)-symmetry parameter $\\alpha_{D}=D/F+D=.58$, taken for both magnetic moments and axial-vector constants entering into the semi-leptonic baryon decays, we obtain the following values for moments $\\Delta q$ of the spin-dependent structure function of the proton: $\\Delta u \\simeq .84(.82), \\Delta d \\simeq -.42(-.44), correspond to the widely used "standard" value of $\\alpha^{axial}_{D}=.63$. The estimations of the strange sea contributions to the nucleon magnetic moments and rms are also presented.
Mapping High x Structure of the Nucleon: which data is missing?
International Nuclear Information System (INIS)
The analysis of numerous experiments on lepton-nucleon and lepton-nucleus deep inelastic scattering reveals several non-trivial features of the nucleon structure, which are particularly interesting in the range of large Bjorken x (x > 0.8). It is shown that new data form the lightest nuclei can provide decisive information needed for the understanding of the nucleon structure
$q \\to \\Lambda$ Fragmentation Function and Nucleon Transversity Distribution in a Diquark Model
Yang Jian Jun
2002-01-01
Based on a simple quark-diquark model, we propose a set of unpolarized, longitudinally polarized and transversely polarized fragmentation functions for the $\\Lambda$ by fitting the unpolarized $\\Lambda$ production data in $e^+ e ^- $ annihilation. It is found that the helicity structure of the obtained $\\Lambda$ fragmentation functions is supported by the all available experimental data on the longitudinal $\\Lambda$ polarization. Within the same framework of the diquark model, the nucleon transversity distributions are presented and consistent descriptions of the available HERMES data on the azimuthal spin asymmetries in pion electroproduction are obtained. Furthermore, the spin transfers to the transversely polarized $\\Lambda$ in the charged lepton DIS on a transversely polarized nucleon target are predicted for future experiments.
q{yields}{lambda} fragmentation function and nucleon transversity distribution in a diquark model
Energy Technology Data Exchange (ETDEWEB)
Yang, Jian-Jun E-mail: jjyang@fis.utfsm.cl
2002-03-11
Based on a simple quark-diquark model, we propose a set of unpolarized, longitudinally polarized and transversely polarized fragmentation functions for the {lambda} by fitting the unpolarized {lambda} production data in e{sup +}e{sup -} annihilation. It is found that the helicity structure of the obtained {lambda} fragmentation functions is supported by the all available experimental data on the longitudinal {lambda} polarization. Within the same framework of the diquark model, the nucleon transversity distributions are presented and consistent descriptions of the available HERMES data on the azimuthal spin asymmetries in pion electroproduction are obtained. Furthermore, the spin transfers to the transversely polarized {lambda} in the charged-lepton DIS on a transversely polarized nucleon target are predicted for future experiments.
Model independent study of the Dirac structure of the nucleon-nucleon interaction
Plohl, O; Van Dalen, E N E
2006-01-01
Relativistic and non-relativistic modern nucleon-nucleon potentials are mapped on a relativistic operator basis using projection techniques. This allows to compare the various potentials at the level of covariant amplitudes were a remarkable agreement is found. In nuclear matter large scalar and vector mean fields of several hundred MeV magnitude are generated at tree level. This is found to be a model independent feature of the nucleon-nucleon interaction.
Transverse spin structure of the nucleon from lattice QCD simulations
International Nuclear Information System (INIS)
We present the first calculation in lattice QCD of the lowest two moments of transverse spin densities of quarks in the nucleon. They encode correlations between quark spin and orbital angular momentum. Our dynamical simulations are based on two flavors of clover-improved Wilson fermions and Wilson gluons. We find significant contributions from certain quark helicity flip generalized parton distributions, leading to strongly distorted densities of transversely polarized quarks in the nucleon. In particular, based on our results and recent arguments by Burkardt [Phys. Rev. D 72 (2005) 094020], we predict that the Boer-Mulders-function h1perpendicularto, describing correlations of transverse quark spin and intrinsic transverse momentum of quarks, is large and negative for both up and down quarks. (orig.)
From Constituent Quark to Hadron Structure in the Next-to-Leading Order Nucleon and Pion
Arash, F; Arash, Firooz; Khorramian, Ali Naghi
2000-01-01
We calculate the partonic structure of constituent quark in the Next-to-Leading Order for the first time. The structure of any hadron can be obtained thereafter using a convolution method. Such a procedure is used to generate the structure function of proton and pion in NLO. It is shown that while the constituent quark structure is generated purely perturbatively and accounts to most part of the hadronic structure, there is a few percent contributions 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 Gottfried sum rule. These effects are calculated. Excellent agreement with data in a wide range of $x=[10^{-6}, 1]$ and $Q^{2}=[0.5, 5000]$ $GeV^{2}$ is reached for proton structure function. We have also calculated Pion structure and compared it with the existing data. Again nice agreement is achieved.
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
Off-shell electron-nucleon cross section and quasielastic response functions RL and RT
International Nuclear Information System (INIS)
A new reduced version of the relativistic half off-shell virtual photon-nucleon vertex is suggested. The gauge invariance, on-shell condition and bound Dirac equation for initial nucleon state are used. Using this vertex, the quasielastic response functions RL and RT for medium heavy nuclei are evaluated and compared with the experimental data. The off-shell electron-nucleon cross section is also calculated and compared with other off-shell extrapolation. (author)
The meson polarized distribution function and mass dependence of the nucleon parton densities
Mirjalili, A
2014-01-01
The polarized distribution functions of mesons, including pion, kaon and eta, using the proton structure function, are calculated. We are looking for a relationship between the polarized distribution of mesons and the polarized structure of nucleons. We show that the meson polarized parton distributions leads to zero total spin for the concerned mesons, considering the orbital angular momentum of quarks and gluons inside the meson. Two separate Monte Carlo algorithms are applied to compute the polarized parton distributions of the kaon. Via the mass dependence of quark distributions, the distribution function of the eta meson is obtained. A new method by which the polarized sea quark distributions of protons are evolved separately -- which cannot be performed easily using the standard solution of DGLAP equations -- is introduced. The mass dependence of these distributions is obtained, using the renormalization group equation which makes their evolutions more precise. Comparison between the evolved distributio...
Polarized lepton-nucleon scattering
International Nuclear Information System (INIS)
Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions
Shell-structure influence on the multinucleon transfer in nucleon transfer matrix elements
International Nuclear Information System (INIS)
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. (author)
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
The polarized structure function with an effective potential
International Nuclear Information System (INIS)
We use a quark model, with an effective potential, to obtain the polarized structure function of the quarks in the nucleon. In the present approach, we consider the harmonic oscillator potential for the quarks. (author)
Nucleon electromagnetic structure studies in the spacelike and timelike regions
Energy Technology Data Exchange (ETDEWEB)
Guttmann, Julia
2013-07-23
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{sup +}p/e{sup -}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{sup +}e{sup -} 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??{sup 0}e{sup +}e{sup -} 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?>?{sup 0}?.
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?.
Relationship between Feshbach's and Green's function theories of the nucleon-nucleus mean field
International Nuclear Information System (INIS)
We clarify the relationship and difference between theories of the optical-model potential which had previously been developed in the framework of Feshbach's projection operator approach to nuclear reactions and of Green's function theory, respectively. For definiteness, we consider the nucleon-nucleus system but all results can readily be adapted to the atomic case. The effects of antisymmetrization are properly taken into account. It is shown that one can develop along closely parallel lines the theories of open-quotes holeclose quotes and open-quotes particleclose quotes mean fields. The open-quotes holeclose quotes one-body Hamiltonians describe the single-particle properties of the system formed when one nucleon is taken away from the target ground state, for instance in knockout of pickup processes. The particle one-body Hamiltonians are associated with the system formed when one nucleon is elastically scattered from the ground state, or is added to it by means of stripping reactions. An infinite number of particle, as well as of hole, Hamiltonians are constructed which all yield exactly the same single-particle wave functions. Many open-quotes equivalentclose quotes one-body Hamiltonians can coexist because these operators have a complicated structure: they are nonlocal, complex, and energy-dependent. They do not have the same analytic properties in the complex energy plane. Their real and imaginary parts fulfill dispersion relations which may be different. It is shown that hole and particle Hamiltonians can also be constructed by decomposing any vector of the Hilbert space into two parts which are not orthogonal to one another, in contrast to Feshbach's original theory; one interest of this procedure is that the construction and properties of the corresponding hole Hamiltonian can be justified in a mathematically rigorous way. We exhibit the relationship between the hole and particle Hamiltonians and the open-quotes mass operator.close quotes
Complete spin structure of the pion-nucleon-loop delta self-energy
International Nuclear Information System (INIS)
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-3/2 isospin-3/2 channel is studied. (author)
What the lattice can tell us about nucleon structure
Schroers, Wolfram
2005-01-01
This review focuses on the current status of lattice calculations of three observables which are both phenomenologically and experimentally relevant and have been scrutinized recently. These three observables are the nucleon electromagnetic form factors, the momentum fraction, , and the nucleon axial coupling, gA.
Quark structure of nucleons: experimental results of BCDMS, SMC (CERN) and HERMES (DESY)
International Nuclear Information System (INIS)
The review of the physics results of the nucleon quark-structure investigation in the completed experiments BCDMS and SMC (CERN) as well as current experiment at the HERMES set-up (DESY) is given. The perspectives of the further investigations of the nucleon spin physics are discussed in the context of future experiments at the COMPASS (CERN) and STAR (BNL) set-up
?N, ?N interactions: structure functions, higher twist
International Nuclear Information System (INIS)
Data on deep inelastic scattering of leptons by nucleons and nuclei have been accumulated for several years. Results exist from several experiments with electron, muon, neutrino beams. In this talk I shall review the most recent experiments which measured nucleon structure functions with ? and ? beams. In particular, I will summarize the results on R = sigma/sub L//sigma/sub T/ measurement, on F2(x,Q2), and xF3(x,Q2), and their interpretation in terms of QCD, including both gluon radiation and higher twist phenomena
Influence of the nucleon spectral function in photon and electron induced reactions on nuclei
International Nuclear Information System (INIS)
We study the influence of the nucleon spectral function on ? photoproduction and electroproduction on nuclei. Besides kinematical effects due to ground state correlations, also a modification of the S11(1535) decay width is taken into account, which is caused by the possible decay into nucleons with mass smaller than the pole mass in the medium. Hence, resonances with masses below the free N? threshold can contribute to ? production
Szczurek, A
1999-01-01
The experimental information on nucleon production in lepton deep inelastic scattering (DIS) is rather scarce. Recently there is a growing interest in understanding the mechanism of the production of baryons in DIS, stimulated by recent results on leading protons and neutrons from electron-proton scattering at HERA. I review on different peripheral mechanisms of nucleon (proton or neutron) production in lepton DIS and discuss their role in understanding the spectra of nucleons for both fixed target and collider experiments. In DIS ep to e'Xh, the QCD hardness scale gradually diminishes from the hard scale, Q/sup 2/, in the virtual photon (current) fragmentation region to the soft, hadronic, scale in the proton (target) fragmentation region. This suggests a similarity of the inclusive spectra of leading protons and neutrons, h=p, n, in high energy hadron-proton collisions and in lepton DIS at small Bjorken-x. The semi-inclusive cross section for production of slow protons in charged-current deep inelastic (ant...
Relationship between Feshbach's and Green's function theories of the nucleon-nucleus mean field
International Nuclear Information System (INIS)
We clarify the relationship and difference between theories of the optical-model potential which had previously been developed in the framework of Feshbach's projection operator approach to nuclear reactions and of Green's function theory, respectively. For definiteness, we consider the nucleon-nucleus system but all results can readily be adapted to the atomic case. The effects of antisymmetrization are properly taken into account. It is shown that one can develop along closely parallel lines the theories of 'hole' and 'particle' mean fields. The hole one-body Hamiltonians describe the single-particle properties of the system formed when one nucleon is taken away from the target ground state, for instance in knockout or pickup processes. The particle one-body Hamiltonians are associated with the system formed when one nucleon is elastically scattered from the ground state, or is added to it by means of stripping reactions. An infinite number of particle, as well as of hole, Hamiltonians are constructed which all yield exactly the same single-particle wave functions. Many 'equivalent' one-body Hamiltonians can coexist because these operators have a complicated structure: they are nonlocal, complex, and energy-dependent. They do not have the same analytic properties in the complex energy plane. Their real and imaginary parts fulfill dispersion relations which may be different. It is shown that hole and particle Hamiltonians can also be constructed by decomposing any vector of the Hilbert space into two parts which are not orthogonal to one another, in contrast to Feshbach's original theory; one interest of this procedure is that the construction and properties of the corresponding hole Hamiltonian can be justified in a mathematically rigorous way. We exhibit the relationship between the hole and particle Hamiltonians and the 'mass operator'. The latter is associated to the time-ordered Green's function, rather than to its advanced and retarded parts separately as the hole and particle Hamiltonians. Similarities and differences between the hole and particle Hamiltonians and the mass operator are exhibited by constructing their explicit expressions in the case of nuclear matter, in the framework of second-order perturbation theory. Particular attention is paid to the connection of the mass operator and the various hole and particle Hamiltonians with observables which can be extracted from stripping, pickup and knockout reactions, in particular the spectroscopic factors and the spectral function. Since many different one-body Hamiltonians exist which all yield the same single-particle wave functions, their relative merits and drawbacks need to be discussed, with particular attention to their relationship to empirical shell- and optical-model potentials and to the possibility of developing practical approximation schemes
The role of nucleon structure in finite nuclei
Guichon, P.A.M.; Saito, K; Rodionov, E.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
1995-01-01
The quark-meson coupling model, based on a mean field description of non-overlapping nucleon bags bound by the self-consistent exchange of $\\sigma$, $\\omega$ and $\\rho$ mesons, is extended to investigate the properties of finite nuclei. Using the Born-Oppenheimer approximation to describe the interacting quark-meson system, we derive the effective equation of motion for the nucleon, as well as the self-consistent equations for the meson mean fields. The model is first applie...
Structure of dipole nucleon collective movement in atomic nuclei
International Nuclear Information System (INIS)
Atomic nuclei have different forms of dipole collective movement of nucleons. Here is a very known example - giant (isovector) dipole resonance that were predicted more than 40 years. Another form of dipole collective mode appears from valence nucleons. In Bose particle theory such a collective mode is described by means of s, p, d Bose particles. These Bose particles can be considered duplex nucleons images in the condition j?=0'+, 1-, 2+. If conditions with j?=0+ and j?=2+, are generated by means of identical nucleon coupling then conditions with j?=1- can occur by neutron/proton coupling. In the field of heavy nuclei valence neutrons and protons are at close by different parity energies conditions and strong neutron-proton interaction of these nucleon pairs in excited state generates collective movement of dipole nature. The fact that there is p-Bose particle freedom in atomic nuclei is confirmed by the following. In 210Bi (where there is one proton and neutron over 208Pb magic shell) 1- condition is basic and assigned
Pion and nucleon structure as probed in the reaction ?/sup +-/N ? ?+?-X at 253 GeV
International Nuclear Information System (INIS)
New results are presented from Fermilab experiment E615, in which hadroproduction of muon pairs allows a determination of the quark structure of the initial-state hadrons in the context of a Drell-Yan model. Comparison of muon-pair production by ?+ and ?- beams shows the cross-section ratio follows Drell-Yan model expectations, except for a dip in ?(?+)/?(?-) near x/sub ?/ near 1. The same data are also used to extract the ratio of the sea to valence quark distributions in the nucleon, with improved accuracy for x/sub N/ 2 for the ?- data sample. This provides stronger evidence of a rise in the nucleon structure function for x/sub N/ < 0.06 compared to that extracted in deep-inelastic lepton scattering. The issue is raised of the nonuniqueness of the definition of x/sub ?/ and x/sub N/ 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/sub ?/ = 1 when the definition of Soper is used. 21 refs., 6 figs
Studies of the transverse structure of the nucleon at JLab
Energy Technology Data Exchange (ETDEWEB)
Mirazita, Marco [INFN, Frascati (Italy)
2014-03-01
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.
Nucleon structure in terms of OPE with non-perturbative Wilson coefficients
International Nuclear Information System (INIS)
Lattice calculations could boost our understanding of Deep Inelastic Scattering by evaluating moments of the Nucleon Structure Functions. To this end we study the product of electromagnetic currents between quark states. The Operator Product Expansion (OPE) decomposes it into matrix elements of local operators (depending on the quark momenta) and Wilson coefficients (as functions of the larger photon momenta). For consistency with the matrix elements, we evaluate a set of Wilson coefficients non-perturbatively, based on propagators for numerous momentum sources, on a 243 x 48 lattice. The use of overlap quarks suppresses unwanted operator mixing and lattice artifacts. Results for the leading Wilson coefficients are extracted by means of Singular Value Decomposition. (orig.)
The role of nucleon structure in finite nuclei
International Nuclear Information System (INIS)
The quark-meson coupling model, based on a mean field description of non-overlapping nucleon bags bound by the self-consistent exchange of ?, ? and ? mesons, is extended to investigate the properties of finite nuclei. Using the Born-Oppenheimer approximation to describe the interacting quark-meson system, we derive the effective equation of motion for the nucleon, as well as the self-consistent equations for the meson mean fields. The model is first applied to nuclear matter, after which we show some initial results for finite nuclei. (orig.)
International Nuclear Information System (INIS)
We address and solve the long-standing gauge-invariance problem of the nucleon spin structure. Explicitly gauge-invariant spin and orbital angular momentum operators of quarks and gluons are obtained. This was previously thought to be an impossible task and opens a more promising avenue towards the understanding of the nucleon spin. Our research also justifies the traditional use of the canonical, gauge-dependent angular momentum operators of photons and electrons in the multipole-radiation analysis and labeling of atomic states and sheds much light on the related energy-momentum problem in gauge theories, especially in connection with the nucleon momentum
Nuclear Effects In The F_3 Structure Function For Finite And Asymptotic Q^2
Kulagin, S. A.
1998-01-01
We study nuclear effects in the structure function F_3 which describes the parity violating part of the charged-current neuitrino nucleon deep inelastic scattering. Starting from a covariant approach we derive a factorized expression for the nuclear structure function in terms of nuclear spectral function and off-shell nucleon structure functions valid for arbitrary momentum transfer Q and in the limit of weak nuclear binding, i.e. when a nucleus can be treated as a non-rela...
Azimuthal Asymmetries: Access to Novel Structure Functions
International Nuclear Information System (INIS)
One of the most interesting consequence of non-zero intrinsic transverse momentum of partons in the nucleon is the nontrivial azimuthal dependence of the cross section of hard scattering processes. Many of the observable asymmetries contain unknown functions which provide essential information on the quark and gluon structure. Several of them have been studied in the last few years; we discuss their qualitative and quantitative features in semi-inclusive DIS
Azimuthal Asymmetries: Access to Novel Structure Functions
Oganessyan, K. A.; Asilyan, L. S.; Sanctis, E.; Muccifora, V
2002-01-01
One of the most interesting consequence of non-zero intrinsic transverse momentum of partons in the nucleon is the nontrivial azimuthal dependence of the cross section of hard scattering processes. Many of the observable asymmetries contain unknown functions which provide essential information on the quark and gluon structure. Several of them have been studied in the last few years; we discuss their qualitative and quantitative features in semi-inclusive DIS.
Polarised structure functions from the SMC experiment
International Nuclear Information System (INIS)
The spin muon collaboration (SMC, NA47) at CERN has measured polarised structure functions of the nucleon in the years 1991-1996. All the published data on g1p and g1d are discussed and the new preliminary results of g1p are presented. The test of the Bjorken sum rule and the violation of the Ellis-Jaffe sum rules are also discussed. (orig.)
Nucleon Structure Including High Fock States in AdS/QCD Models
Vega, Alfredo; Schmidt, Ivan; Gutsche, Thomas; Lyubovitskij, Valery E.
2015-09-01
We discuss a holographic soft-wall model that consider several Fock states in nucleon description. In our approach nucleon structure is a superposition of a three-valence quark state with high Fock states including an adjustable number of partons (quarks, antiquarks and gluons). With a minimal number of free parameters (dilaton scale parameter, mixing parameters of partial contributions of Fock states, coupling constants in the effective Lagrangian) we achieve a reasonable agreement with data.
Nucleon Structure from Lattice QCD Using a Nearly Physical Pion Mass
Green, J R; Krieg, S; Negele, J W; Pochinsky, A V; Syritsyn, S N
2012-01-01
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.
Advances on statistical/thermodynamical models for unpolarized structure functions
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus do Mucuri, 39803-371, Teofilo Otoni, Minas Gerais (Brazil); Tomio, Lauro [Instituto de Fisica Teorica, Universidade Estadual Paulista, R. Dr. Bento Teobaldo Ferraz 271, Bl II Barra Funda, 01140070, Sao Paulo, SP (Brazil)
2013-03-25
During the eights and nineties many statistical/thermodynamical models were proposed to describe the nucleons' structure functions and distribution of the quarks in the hadrons. Most of these models describe the compound quarks and gluons inside the nucleon as a Fermi / Bose gas respectively, confined in a MIT bag with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries {sup -}d/{sup -}u and {sup -}d-{sup -}u.
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Mokeev, Victor; Burkert, Volker; Gothe, Ralf
2015-01-01
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and $N \\rightarrow N^*$ transition form factors. We will also discuss further convincing evidences for a new baryon state $N^{\\, '}(1720)3/2^+$ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
The role of strangeness in the nucleon structure
International Nuclear Information System (INIS)
It is shown that by reformulating an SU(3) Skyrmion model as a random phase approximation (RPA) to an underlying fermion (quark) theory, one can calculate microscopic (quark) properties of the nucleon without explicit account of the quark-gluon degrees of freedom. In this paper, the strangeness content of the proton can be estimated with a Skyrmion model that describes well the hyperon spectroscopy
Unpolarized nucleon structure studies utilizing polarized electromagnetic probes
International Nuclear Information System (INIS)
By the mid-1980s, measurements of the nucleon form factors had reached a stage where only slow, incremental progress was possible using unpolarized electron scattering. The development of high quality polarized beams, polarized targets, and recoil polarimeters led to a renaissance in the experimental program. I provide an overview of the changes in the field in the last ten years, which were driven by the dramatically improved data made possible by a new family of tools to measure polarization observables
International Nuclear Information System (INIS)
The x dependence of hadron structure functions is investigated. If quarks can exist in very low mass states (10 MeV for d and u quarks) the pion structure function is predicted to behave like (1-x) and not (1-x)2 in a x-region around 1. Relativistic and non-relativistic quark bound state pictures of hadrons are considered together with their relation with the Q2 evolution of structure functions. Good agreement with data is in general obtained
Experimental Studies of Quark-Gluon Structure of Nucleons and Nuclei
International Nuclear Information System (INIS)
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
Searching for structure in nucleon-antinucleon interactions near threshold
International Nuclear Information System (INIS)
The purpose of this paper is to help make the case for a new machine being an antiproton factory as well as a kaon factory. The energy of such a high-intensity accelerator should be near 30 GeV, rather than the 15 GeV which would be adequate for the production of kaons as the most massive particle. Primarily, we wish to point out that there are regions of nucleon-antinucleon interactions which have not been carefully explored and which may contain interesting phenomena despite existing negative experiments
Impact of the recent Jefferson lab data on the structure of the nucleon
Scientific Electronic Library Online (English)
W.R.B. de, Araújo; T., Frederico; M., Beyer; H.J., Weber.
2004-03-01
Full Text Available 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.
Pion nucleon vertex function and the one pion exchange potential
International Nuclear Information System (INIS)
The ?NN vertex function is calculated from field theory and dispersion relations. It contains no adjustable parameters, the only input being S- and P-wave for ???N anti-N. This vertex function, having an effective cut-off mass of 5? and a r.m.s. radius of 52fm, compares well with previous experimental determinations. The effects from the 3? dressing of the ? propagator are found to be negligible. The corrected OPEP is significantly different from the uncorrected one-pion exchange potentiel (OPEP) for r<1.5fm. The inclusion of the corrected OPEP in meson exchange potentials will improve agreement with phenomenology
Study of two-nucleon wave functions in 3He
International Nuclear Information System (INIS)
The 3He(p,2p)pn reaction has been studied in a quasi-free scattering arrangement characterized by (anti) p(recoil) = 0 and various excitation or total energies E(recoil) of the unobserved p-n pair. Data were obtained at 250 and 400 MeV at symmetric and asymmetric pairs of angles. The 3He spectral function deduced in the framework of the plane wave impulse approximation is compared to the predictions of Faddeev and variational calculations. Comparisons are also made with p-n relative motion momentum distributions as the overlap between plane waves for the p-n pair and Irving, Irving-Gunn and Khanna wave functions for 3He
Structure of the real part of the nucleon optical potential
International Nuclear Information System (INIS)
The components of the nucleon optical potential V(l, E) in the 208Pb and 40Ca nuclei are calculated on the basis of the generalized Hartree-Fock potential and using typical sets of vacuum NN forces. The parameters of the isoscalar component of V(1, E) are found to agree well with those of phenomenological optical potentials and of the optical potentials in the Skyrme model. The isovector component of V(1, E) strongly depends on energy, and its value at E = 0 is considerably less than the corresponding values of the phenomenological and Skyrme optical potentials. This points to the necessity of additional tests of the underlying pair NN potentials. The radial distribution of V(1, E) is more complicated than the radial dependence of phenomenological optical potentials. 6 refs., 5 figs
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)
Recent COMPASS results on the nucleon longitudinal spin structure and QCD fits
Directory of Open Access Journals (Sweden)
Andrieux Vincent
2014-01-01
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.
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)
McGraw, John T. (Placitas, NM); Zimmer, Peter C. (Albuquerque, NM); Ackermann, Mark R. (Albuquerque, NM)
2012-01-24
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.
Purely Functional Structured Programming
Obua, Steven
2010-01-01
The idea of functional programming has played a big role in shaping today's landscape of mainstream programming languages. Another concept that dominates the current programming style is Dijkstra's structured programming. Both concepts have been successfully married, for example in the programming language Scala. This paper proposes how the same can be achieved for structured programming and PURELY functional programming via the notion of LINEAR SCOPE. One advantage of this ...
Challenges in the global QCD analysis of parton structure of nucleons
International Nuclear Information System (INIS)
We briefly summarize the current status of global QCD analysis of the parton structure of the nucleon and then highlight the open questions and challenges which confront this endeavor on which much of the phenomenology of the Standard Model and the search of New Physics depend
A pure $S$-wave covariant model for the nucleon
Energy Technology Data Exchange (ETDEWEB)
Franz Gross; G. Ramalho; M.T. Pena
2008-01-01
Using the manifestly covariant spectator theory, and modeling the nucleon as a system of three constituent quarks with their own electromagnetic structure, we show that all four nucleon electromagnetic form factors can be very well described by a manifestly covariant nucleon wave function with zero orbital angular momentum.
Measurement of spin structure functions at SLAC: a status report on the E143 experiment
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. copyright 1995 American Institute of Physics
Initial nucleon structure results with chiral quarks at the physical point
Syritsyn, S; Engelhardt, M; Green, J; Izubuchi, T; Jung, C; Krieg, S; Lin, M; Meinel, S; Negele, J; Ohta, S; Pochinsky, A; Shintani, E
2014-01-01
We report initial nucleon structure results computed on lattices with 2+1 dynamical M\\"obius domain wall fermions at the physical point generated by the RBC and UKQCD collaborations. At this stage, we evaluate only connected quark contributions. In particular, we discuss the nucleon vector and axial-vector form factors, nucleon axial charge and the isovector quark momentum fraction. From currently available statistics, we estimate the stochastic accuracy of the determination of $g_A$ and $_{u-d}$ to be around 10%, and we expect to reduce that to 5% within the next year. To reduce the computational cost of our calculations, we extensively use acceleration techniques such as low-eigenmode deflation and all-mode-averaging (AMA). We present a method for choosing optimal AMA parameters.
International Nuclear Information System (INIS)
Nucleon-trinucleon overlap functions in 4He have been parametrized as a sum of exponentials, and are fitted to the charge form factor of4He. We present results with and without taking account of meson-exchange corrections
Chromatin Structure and Function
Wolffe, Alan P
1999-01-01
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
Photon structure function revisited
Berger, Ch
2014-01-01
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.
Lepton Scattering on Nuclei at $x$ > 1 and the Nucleon Spectral Function
De Córdoba, P F; Müther, H; Oset, E; Faessler, A
1998-01-01
We analyze the processes of deep inelastic and quasielastic scattering in the region of x > 1. These processes are found to be very sensitive to the information contained in the nucleon spectral function in nuclei, particularly to the correlations between energy and momentum. Calculations are done using two spectral functions for nuclear matter and one for finite nuclei, ^{16}O. Several approximations are also analyzed and are shown to be inaccurate in this region. These results stress the fact that the region of x > 1 contains important information on nuclear dynamical correlations.
Neutron Structure Functions From Nuclear Data
Melnitchouk, W; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
1996-01-01
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 ...
International Nuclear Information System (INIS)
The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter PD ?1/4 (which specifies deformation) fits gA (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(?N?), the double delta coupling constant1 fsub(???), the Ml transition moment ??N and g1p the spin structure function of proton2. All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs
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
Neutron Structure Function and A=3 Mirror Nuclei
Afnan, I. R.; Bissey, F.; Gomez, J; Katramatou, A.T.; Melnitchouk, W; Petratos, G.G.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
2000-01-01
We investigate deep inelastic scattering from He-3 and H-3 within a conventional convolution treatment of binding and Fermi motion effects. Using realistic Faddeev wave functions together with a nucleon spectral function, we demonstrate that the free neutron structure function can be extracted in deep-inelastic scattering from A=3 mirror nuclei, with nuclear effects canceling to within 2% for x < 0.85.
Lynn, J E
2015-01-01
I discuss our recent work on Green's function Monte Carlo (GFMC) calculations of light nuclei using local nucleon-nucleon interactions derived from chiral effective field theory (EFT) up to next-to-next-to-leading order (N$^2$LO). I present the natural extension of this work to include the consistent three-nucleon (3N) forces at the same order in the chiral expansion. I discuss our choice of observables to fit the two low-energy constants which enter in the 3N sector at N$^2$LO and present some results for light nuclei.
International Nuclear Information System (INIS)
Fundamental interactions of spinning electrons at an interelectron separation less than 578.8 fm yield attractive electromagnetic forces with S = 0 creating vibrations under a motional emf. They explain the indistinguishability of electrons and give a vibration energy able for calculating the ground-state energies of many-electron atoms without using any perturbative approximation. Such forces create two-electron orbitals able to account for the exclusion principal and the mechanism of covalent bonds. In the outer subshells of atoms the penetrating orbitals interact also as pair-pair systems and deform drastically the probability densities of the quantum mechanical electron clouds. Such a dynamics of deformation removes the degeneracy and leads to the deviation from the shell scheme. However in the interior of atoms the large nuclear charge leads to a spherically symmetric potential with non-interacting pairs for creating shells of degenerate states giving an accurate explanation of the X-ray lines. On the other hand, considerable charge distributions in nucleons as multiples of 2e/3 and - e/3 determined by the magnetic moments, interact for creating the nuclear structure with p-n bonds. Such spin-spin interactions show that the dominant concept of the untisymmetric wave function for fermions is inapplicable not only in the simple p-n, p-p, and n-n systems but also in the LS coupling of atoms in which the electrons interact from different quantum states giving either S = 0 or S = l. (author)
Mallot, Gerhard K.
1997-01-01
The experimental status of the spin-dependent structure functions as obtained from the deep inelastic scattering experiments at CERN, SLAC, and DESY is reviewed. All data show a violation of the Ellis-Jaffe sum rule. The Bjorken sum rule is found to be valid and is tested to the 10 % level.
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.)
International Nuclear Information System (INIS)
When the new data on polarised lepton nucleon scattering are compared at the same value of Q2 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(?s), higher twist effects, modern data on unpolarized 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. (author)
International Nuclear Information System (INIS)
When the new data on polarised lepton nucleon scattering are compared at the same value of Q2 and with a common set of assumptions, a consistent picture of the spin content of the nucleon begins to emerge. Higher order effects in O(?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. (author)
Neutron structure function from nuclear data
Energy Technology Data Exchange (ETDEWEB)
Melnitchouk, W. [Dept. of Physics, Univ. of Maryland, College Park, MD (United States); Thomas, A.W. [Dept. of Physics and Mathematical Physics, Univ. of Adelaide, Adelaide (Australia)
1996-06-01
The spin-averaged structure function of the neutron, F{sub 2}{sup n}, is extracted from the latest deuteron data, taking into account the most recent developments in the treatment of nuclear effects in the deuteron. At small x, the F{sub 2}{sup D}/F{sub 2}{sup p} 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{sub 2}{sup n} for x {approx}< 0.1. A careful treatment of Fermi motion, binding and nucleon off shell effects in the deuteron also indicates that the neutron/proton structure function ratio as x {yields} 1 is consistent with the perturbative QCD expectation of 3/7, but larger than the traditional value of 1/4. (author) 40 refs, 5 figs
The scale dependence of single-nucleon shell structure
Somà, V.; Duguet, T.; Hergert, H.; Holt, J. D.
2015-10-01
We address the scale dependence of (effective) single-particle energies, non-observable quantities that are commonly used for interpreting nuclear structure observables measured in experiments and computed in many-body theories. We first demonstrate their scale dependence on a formal level, making them intrinsically theoretical objects, before illustrating this point via ab initio calculations in the oxygen isotopes. Finally, we consider a modified definition of effective single-particle energy and investigate its running properties.
Progress in resolving charge symmetry violation in nucleon structure
Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale, CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA, 5005, Australia); Shanahan, P. E.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
2013-01-01
Recent work unambiguously resolves the level of charge symmetry violation in moments of parton distributions using 2+1-flavor lattice QCD. We introduce the methods used for that analysis by applying them to determine the strong contribution to the proton-neutron mass difference. We also summarize related work which reveals that the fraction of baryon spin which is carried by the quarks is in fact structure-dependent rather than universal across the baryon octet.
Deep Inelastic Structure Functions in a Covariant Spectator Model
Kusaka, K.; Piller, G.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia); Williams, A. G.
1996-01-01
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.
Deuteron Spin Structure Functions in the Resonance and DIS Regions
Energy Technology Data Exchange (ETDEWEB)
S. Kulagin; W. Melnitchouk
2007-10-03
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.
Nuclear Effects on the Extraction of Neutron Structure Functions
Schmidt, I; Schmidt, Ivan; Yang, Jian-Jun
2001-01-01
Nuclear effects in light nuclei due to the presence of spin-one isosinglet 6-quark clusters are investigated. The quark distributions of 6-quark clusters are obtained by using a perturbative QCD (pQCD) based framework, which allows us to get a good description of the ratio of the deuteron structure function to the free nucleon structure function. Nuclear effects on the extraction of the neutron structure functions $F_2^n$ and $g_1^n$ are estimated. We find that the effect on the extracted spin-dependent neutron structure function is very different from that on the spin-independent neutron structure function. The effect enhances the Bjorken sum by about 10%, whereas its correction to the Gottfried sum is rather small. The formalism for calculating nuclear effects is further used to evaluate the spin-dependent structure function of the $^3$He nucleus and a good self-consistent check is obtained.
What we can learn about nucleon spin structure from recent data
Goshtasbpour, M; Ramsey, Gordon P
1997-01-01
We have used recent polarized deep-inelastic scattering data from CERN and SLAC to extract information about nucleon spin structure. We find that the SMC proton data, the E142 neutron data and the deuteron data from 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 occuring 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.
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
Exchange currents and the internal structure of the nucleon in quark models
International Nuclear Information System (INIS)
The influence of internal nucleon structure on meson exchange currents has been investigated, in the framework of the non-relativistic constituent quark model and the MIT bag model with massless quarks. In comparison with the conventional theory of exchange currents, different strengths are found for the model-dependent higher-order terms and no ambiguity between pseudoscalar and pseudovector pion couplings. Furthermore, the retardation and excitation effects in the many-body system have to be treated consistently, in order to preserve gauge invariance. In this way 'damping' factors are obtained which differ in structure from the phenomenological form factors. (author)
DEFF Research Database (Denmark)
Sinden, Richard R.; E. Pearson, Christopher; N. Potaman, Vladimir; Ussery, David
1998-01-01
This chapter discusses the structure and function of DNA. DNA occupies a critical role in cells, because it is the source of all intrinsic genetic information. Chemically, DNA is a very stable molecule, a characteristic important for a macromolecule that may have to persist in an intact form for a long period of time before its information is accessed by the cell. Although DNA plays a critical role as an informational storage molecule, it is by no means as unexciting as a computer tape or disk d...
Energy Technology Data Exchange (ETDEWEB)
Navratil, P; Caurier, E
2003-10-14
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.
Nucleon Compton scattering in the Dyson-Schwinger approach
International Nuclear Information System (INIS)
Full text: Compton scattering on the nucleon provides a unique tool to probe the nonperturbative structure of the nucleon. It allows access to a range of observables that are subject to studies at major experimental facilities, including: the nucleon's generalized polarizabilities; two-photon contributions to form factors; nucleon structure functions and generalized parton distributions; and proton antiproton annihilation processes. A nonperturbative approach for investigating such phenomena is given by the combination of QCD's Dyson-Schwinger equations with covariant Bethe-Salpeter and Faddeev equations. The framework has been recently applied for describing nucleon and delta elastic and transition form factors, and its systematic extension to Compton scattering, pion electroproduction and nucleon-pion scattering has been outlined. I will discuss recent progress in this area and present rst results for the nucleon's Compton scattering amplitude. (author)
Monte Carlo Generators for Studies of the 3D Structure of the Nucleon
Energy Technology Data Exchange (ETDEWEB)
Avagyan, Harut A. [JLAB
2015-01-01
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.
Hyperfine structure of ground-state nucleons in chiral quark model
Jia, Duojie; Dang, Wen-Bo; Zhao, Xing-Wen
2015-10-01
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.
Status of nucleon structure calculations with 2+1 flavors of domain wall fermions
Lin, Meifeng
2013-01-01
We report the status of our nucleon structure calculations with 2+1 flavors of domain wall fermions on the RBC-UKQCD $32^3\\times64$ gauge ensembles with the Iwasaki+DSDR action. These ensembles have a fixed lattice scale of 1/a = 1.37 GeV, and two pion masses of about 170 and 250 MeV. Preliminary results for the isovector electromagnectic form factors and their corresponding root-mean-squared (r.m.s.) radii will be presented.
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
International Nuclear Information System (INIS)
The spin structure function g1(x, Q2) and the related longitudinally polarized parton densities ?f-(-)(x,Q2) are discussed in LO and NLO QCD for different factorization schemes within the common 'standard' scenario of polarized parton distributing functions (pdfs) with a flavour-symmetric light sea (antiquark) distribution ?q-bar and a completely SU(3)f broken 'valence' scenario with totally flavour-asymmetric light sea densities (?u-bar??d-bar??s-bar). The latter flavour-broken light sea densities are modelled with the help of a Pauli-blocking ansatz which complies with predictions of the chiral quark-soliton model and expectations based on the statistical parton model as well as with the corresponding, well established, flavour-broken unpolarized sea (d-bar>u-bar). Various parametrizations of polarized pdfs and results of recent analyses are discussed and compared, with particular emphasis on their implications at small x and for the polarized gluon distributions ?g(x, Q2). Further (future) direct measurements of ?u-bar and ?d-bar are discussed and suggested, such as polarized semi-inclusive DIS production processes of charged hadrons, polarized Drell-Yan (?*) dilepton production processes for future longitudinally polarized p-vector p-vector and p-vector d-vector collision experiments, and the production of weak vector bosons (W±, Z0) via singly and doubly longitudinally polarized pp and pn collisions. (author)
Quark-diquark approximation of the three-quark structure of a nucleon and the NN phase shifts
International Nuclear Information System (INIS)
The quark-diquark approximations of the three-quark structure of a nucleon are considered in the framework of the quark confinement model (QCM) based on definite concepts of the hadronization and quark confinement. The static nucleon characteristics (magnetic moments, ratio GA/GV and strong meson-nucleon coupling constants) are calculated. The behaviour of the electromagnetic and strong nucleon form factors is obtained at the low energy (0?02=-q22, where q is a transfer momentum). The one-boson exchange potential is constructed and the NN-phase-shifts are computed. Our results are compared with experiment and the Bonn potential model. 45 refs.; 7 figs.; 3 tabs
High energy proton-proton elastic scattering at the Large Hadron Collider and nucleon structure
Luddy, Richard Joseph
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.
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?
Spin structure function measurements with polarized protons and electrons at HERA
International Nuclear Information System (INIS)
Useful insights into the spin structure functions of the nucleon can be achieved by measurements of spin-dependent asymmetries in inclusive scattering of high energy polarized electrons by high energy polarized protons at HERA. Such an experiment would be a natural extension of the polarized lepton-nucleon scattering experiments presently carried out at CERN and SLAC. We present here estimates of possible data in the extended kinematic range of HERA and associated statistical errors. (orig.)
Neutron/Proton Structure Function Ratio at Large x
Melnitchouk, W; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
1996-01-01
We re-examine the large-x neutron/proton structure function ratio extracted from the latest deuteron data, taking into account the most recent developments in the treatment of Fermi motion, binding and nucleon off-shell effects in the deuteron. Our findings suggest that as x->1 the ratio of the neutron to proton structure functions (F_2^n/F_2^p) is consistent with the perturbative QCD expectation of 3/7, but larger than the value of 1/4 obtained in earlier analyses.
Litvinova, Elena
2015-01-01
The relativistic particle-vibration coupling (RPVC) model is extended by the inclusion of spin- and isospin-flip excitation modes into the phonon space, introducing a new mechanism of dynamical interaction between nucleons with different isospin in the nuclear medium. Protons and neutrons exchange by collective modes which are formed by isovector $\\pi$ and $\\rho$-mesons, in turn, softened considerably because of coupling to nucleons of the medium. These modes are investigated within the proton-neutron relativistic random phase approximation (pn-RRPA) and relativistic proton-neutron time blocking approximation (pn-RTBA). The appearance of isospin-flip states with sizable transition probabilities at low energies points out that they are likely to couple to the single-particle degrees of freedom and, in addition to isoscalar low-lying phonons, to modify their spectroscopic characteristics. Such a coupling is quantified for the shell structure of $^{100,132}$Sn and found significant for the location of the domina...
pp Elastic Scattering at LHC in a Nucleon-Structure Model
Islam, M M; Luddy, R J
2007-01-01
We predict pp elastic differential cross sections at LHC at c.m. energy 14 TeV and momentum transfer range |t| = 0 - 10 GeV*2 in a nucleon-structure model. In this model, the nucleon has an outer cloud of quark-antiquark condensed ground state, an inner shell of topological baryonic charge (r ~ 0.44F) probed by the vector meson omega, and a central quark-bag (r ~ 0.2F) containing valence quarks. We also predict elastic differential cross section in the Coulomb-hadronic interference region. Large |t| elastic scattering in this model arises from valence quark-quark scattering, which is taken to be due to the hard-pomeron (BFKL pomeron with next to leading order corrections). We present results of taking into account multiple hard-pomeron exchanges, i.e. unitarity corrections. Finally, we compare our prediction of pp elastic differential cross section at LHC with the predictions of various other models. Precise measurement of pp elastic differential cross section at LHC by the TOTEM group in the |t| region 0 - 5...
Nucleon quark distributions in a covariant quark-diquark model
Cloet, I. C.; Bentz, W.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
2005-01-01
Spin-dependent and spin-independent quark light-cone momentum distributions and structure functions are calculated for the nucleon. We utilize a modified Nambu-Jona-Lasinio model in which confinement is simulated by eliminating unphysical thresholds for nucleon decay into quarks. The nucleon bound state is obtained by solving the Faddeev equation in the quark-diquark approximation, where both scalar and axial-vector diquark channels are included. We find excellent agreement ...
Bound Nucleon Form Factors, Quark-Hadron Duality, and Nuclear EMC Effect
Tsushima, K.; Lu, D. H.; Melnitchouk, W; Saito, K; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
2003-01-01
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 ...
Spin structure functions: a window into the structure of hadrons
International Nuclear Information System (INIS)
A large program of spin structure measurements is underway in Jefferson Lab's Hall B. Of particular interest is the first moment of the spin structure function g1, which goes through a rapid transition from the photon point (Q2 = 0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. One can then study the transition from hadronic to quark degrees of freedom over the whole range of Q2. It is also interesting to look for the onset of quark-hadron duality in spin structure functions. We use longitudinally polarized electrons with energies from 1.6 to 5.7 GeV incident upon polarized NH3 and ND3 targets to investigate proton and deuteron spin observables in and above the resonance region. We present the GDH and Bjorken integrals using the 1.6 and 5.7 GeV data and comment on the validity of local quark-hadron duality over the wide kinematical range (0.05 ? Q2 ? 4.5 GeV2 and W < 3.2 GeV) covered by this experiment
Neutral current neutrino-nucleon scattering
International Nuclear Information System (INIS)
It may appear unusual to have a contribution on neutrino scattering at a school devoted to electromagnetic probes, as the neutrino has no known electromagnetic couplings. However, as a means to examine the hidden flavor currents in the nucleon, the recent results observed for the spin structure function of the nucleon have focused attention on the nucleon's neutral weak currents (NWC). When an electromagnetic probe is scattered elastically from a nucleon, the NWC interactions are observable only through the detection of very small (> 10-6) parity-violating processes. In the case of neutrino scattering, the NWC is the dominant coupling. In what follows it will be shown how the nucleon's vector and axial vector form factors arising from strange quark currents can be measured via neutrino elastic scattering. Preliminary results from the Large Scintillation Neutrino Detector (LSND) at LAMPF will be presented as well as a recent analysis of an earlier experiment (E734) carried out at Brookhaven
Exclusive pion electroproduction off nucleons and nuclei
Kaskulov, Murat M
2011-01-01
We present our results for the exclusive electroproduction of pions off nucleons and nuclei at high values of $Q^2$. In electroproduction of nuclei $A(e,e'\\pi)$ we consider the Color Transparency (CT) effect recently observed at JLAB. It is shown that the description of $\\pi$ production off nucleons is mandatory for the proof of the CT signal at JLAB. We further develop the models for exclusive production of $\\pi$ off nucleons at JLAB and HERMES. At first we describe a model based on exclusive-inclusive connection. In the second approach we combine a Regge pole approach with the residual effect of nucleon resonances. The nucleon resonances are described using a dual connection between the exclusive form factors and inclusive deep inelastic structure functions. We present the results for the beam spin azimuthal asymmetries measured at JLAB in exclusive electroproduction of charged and neutral pions.
Comba, Peter
2010-01-01
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
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
Ab initio Nuclear structure Theory with chiral two- plus three-nucleon interactions
International Nuclear Information System (INIS)
Low-energy nuclear theory has entered an era of ab initio nuclear structure and reaction calculations based on input from QCD. One of the most promising paths from QCD to nuclear observables employs Hamiltonians constructed within chiral effective field theory as consistent starting point for precise ab initio nuclear structure and reaction studies. However, the full inclusion of chiral two- plus three-nucleon (NN+3N) interactions in exact and approximate many-body calculations still poses a formidable challenge. We discuss recent developments towards this goal, ranging from consistent Similarity Renormalization Group evolutions of NN+3N Hamiltonians to large-scale ab initio calculations for ground states and spectra in the Importance-Truncated No-Core Shell Model with full 3N interactions. We highlight recent achievements and discuss open issues and future perspectives for nuclear structure theory with QCD-based interactions. Moreover, we discuss successful steps towards merging ab initio structure and reaction theory and show applications to low-energy reactions in the p-shell relevant for astrophysics.
Structure functions at large x
International Nuclear Information System (INIS)
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 briefly mentioned. (author)
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
Energy Technology Data Exchange (ETDEWEB)
Azhgirey, L. S.; Afanasiev, S. V.; Borzounov, Yu. T.; Golovanov, L. B.; Zolin, L. S., E-mail: zolin@sunhe.jinr.ru; Ivanov, V. I.; Isupov, A. Yu., E-mail: isupov@moonhe.jinr.ru; Ladygin, V. P.; Litvinenko, A. G.; Malakhov, A. I.; Penev, V. N.; Peresedov, V. F.; Pilipenko, Yu. K.; Reznikov, S. G.; Rukoyatkin, P. A.; Khrenov, A. N. [Joint Institute for Nuclear Research (Russian Federation)
2011-10-15
Experimental results on the vector (A{sub y}) and tensor (A{sub yy}) analyzing powers in the fragmentation of 5- and 9-GeV/c polarized deuterons to high-momentum pions in the kinematical region corresponding to pion production on a strongly correlated nucleon pair (cumulative meson production) are presented. The angular and momentum dependences of A{sub yy} are not described by calculations performed in the impulse approximation by using standard deuteron wave functions. An explanation for our data should be sought on the basis of models that treat the deuteron at short distances (deuteron-core region) as a multiquark state-for example, a 6q cluster, whose high orbital angular momentum (D wave) leads to the observed strong dependence of the reaction tensor analyzing power A(d-vector, {pi})X on the pion transverse momentum.
Probing The Standard Model And Nucleon Structure Via Parity-violating Electron Scattering
Humensky, T B
2003-01-01
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...
Probing the Nucleon's Transversity Via Two-Meson Production in Polarized Nucleon-Nucleon Collisions
Tang, Jian
1998-01-01
We explore the possibility of probing the nucleon's transversity distribution $\\delta q(x)$ through the final state interaction between two mesons ($\\pi^+\\pi^-$, $\\pi K$, or $K\\bar K$) produced in transversely polarized nucleon-nucleon collisions. We present a single spin asymmetry and estimate its magnitude under some assumptions for the transversity distribution function and the unknown interference fragmentation function.
The impact of a neutrino factory upon our knowledge of the internal structure of the nucleon
International Nuclear Information System (INIS)
A neutrino factory, used for short baseline physics, could provide unique and profound information about the internal structure of the nucleon. The unpolarized parton densities are already quite well known, thanks to a combination of neutral and charged current deep inelastic reactions over a wide range of Q2. But with high intensities available from a neutrino factory it would no longer be necessary to utilize heavy nuclear targets, leading to a vast improvement in the precision of the data. However, the impact on our knowledge of the polarized parton densities would be much more dramatic. There the quality of the data is excellent, but because of the impossibility of utilizing polarized targets with present day neutrino beams, charged current data does not exist and the neutral current data only provide information about the combinations [?q(x)+?q-bar(x)]. Thus nothing at all is known about the polarization of the valence quarks and the sea quarks separately! A truly dramatic improvement would follow from the construction of a neutrino factory. (author)
Close, Francis Edwin
1995-01-01
This talk summarises the discussions during the conference on the spin structure of the nucleon held at Erice; July 1995. The summary focuses on where we have come, where we are now, and the emerging questions that direct where we go next in the quest to understand the nucleon spin.
Measurement of the proton spin structure function g1p
International Nuclear Information System (INIS)
In order to check the Bjorken sum rule and confirm the EMC surprising conclusion on the spin structure of the proton, the measurement of the spin structure function of the proton has been performed by the Spin Muon Collaboration via the polarized muon nucleon deep inelastic scattering. The results of the 1993 run are presented within a kinematical range of 0.003 2 = 10 GeV2. The first moment of the polarized spin structure function g1p is found to be two standard deviations below the Ellis-Jaffe sum rule. Assuming SU(3) for hyperons ? decays, the quark spin contribution to the proton spin is extracted. Combining all available data on proton, neutron and deuton, The Bjorken sum rule is confirmed within 10%. (author). 25 refs., 3 figs., 2 tabs
Electromagnetic Structure and Reactions of Few-Nucleon Systems in $\\chi$EFT
Schiavilla R.; Girlanda L.; Pastore S.; Viviani M.
2009-01-01
We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral effective field theory ($\\chi$EFT). The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and the...
Nucleon-Nucleon Interactions from the Quark Model
Downum, Clark; Stone, Jirina; Barnes, TED; Swanson, Eric; Vidana, Isaac
2010-01-01
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...
Comments on pseudoscalar-nucleon coupling
International Nuclear Information System (INIS)
In the light of the recent EMC measurement of polarized muon-proton scattering we reexamine the coupling of the pseudoscalar Higgs boson to nucleons in a class of spontaneous CP-violation models where CP-violation can arise from the scalar-pseudoscalar Higgs boson mixings mechanism. Previous naive estimates of the effective direct Higgs-nucleon coupling can be reduced by taking into account the EMC data on the spin-dependent structure function. We show that this coupling can be consistent with being zero. This implies that the electric dipole moment of neutron induced by this Higgs-nucleon coupling in these models may vanish instead of dominating over the other contributions. Remarks on axion-nucleon coupling are also given
Bound Nucleon Form Factors, Quark-Hadron Duality, and Nuclear EMC Effect
Tsushima, K; Melnitchouk, W; Saitô, K; Thomas, A W
2003-01-01
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.
Nucleon Electromagnetic Form Factors
International Nuclear Information System (INIS)
Although nucleons account for nearly all the visible mass in the universe, they have a complicated structure that is still incompletely understood. The first indication that nucleons have an internal structure, was the measurement of the proton magnetic moment by Frisch and Stern (1933) which revealed a large deviation from the value expected for a point-like Dirac particle. The investigation of the spatial structure of the nucleon, resulting in the first quantitative measurement of the proton charge radius, was initiated by the HEPL (Stanford) experiments in the 1950s, for which Hofstadter was awarded the 1961 Nobel prize. The first indication of a non-zero neutron charge distribution was obtained by scattering thermal neutrons off atomic electrons. The recent revival of its experimental study through the operational implementation of novel instrumentation has instigated a strong theoretical interest. Nucleon electro-magnetic form factors (EMFFs) are optimally studied through the exchange of a virtual photon, in elastic electron-nucleon scattering. The momentum transferred to the nucleon by the virtual photon can be selected to probe different scales of the nucleon, from integral properties such as the charge radius to scaling properties of its internal constituents. Polarization instrumentation, polarized beams and targets, and the measurement of the polarization of the recoiling nucleon have been essential in the accurate separation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor
Chiral three-nucleon interactions in ab-initio nuclear structure and reactions
International Nuclear Information System (INIS)
The prediction of nuclear structure and reaction observables based on nuclear Hamiltonians including two- and three-nucleon (NN+3N) interactions derived from chiral effective field theory constitutes a challenging task for ab-initio nuclear theory. In particular, the consistent inclusion of 3N interactions requires formal extensions of the many-body methods and, at the same time, causes a significant increase of the computational cost. This work presents the necessary steps for the inclusion and the subsequent application of 3N interactions in different ab-initio nuclear structure and reaction approaches. The first part is dedicated to the preparation of the chiral nuclear forces before they enter the many-body methods. It addresses the similarity renormalization group (SRG) as a tool to soften the initial chiral interactions and its generalization to consistently include 3N interactions. Moreover, the technically important 3N matrix-element management in a convenient basis for the subsequent many-body methods including an efficient storage scheme is discussed. In addition, a possibility to derive approximative schemes for 3N interactions using normal ordering is presented. In the second part the SRG-evolved chiral NN+3N Hamiltonians are applied in nuclear structure calculations using the importance truncated no-core shell model (IT-NCSM) as well as coupled-cluster theory. The impact of SRG-induced and chiral 3N interactions on ground-state energies and low-energy spectra of different p-shell nuclei is studied, including a sensitivity analysis concerning uncertainties of the chiral interactions in the 12C and 10B spectra. Furthermore, the first ab-initio study of even oxygen isotopes with explicit 3N interactions is presented, and by means of the normal-ordered two-body approximation the ground-state energy systematics of selected closed-shell nuclei throughout the calcium, nickel, and tin isotopic chains are obtained in qualitative agreement with experiment. The third part of this work focuses on 3N interactions in ab-initio nuclear scattering approaches. This includes a detailed discussion of the inclusion of 3N interactions in the no-core shell model combined with the resonating-group method (NCSM/RGM) with emphasis on the ability to treat targets beyond the lightest nuclei. The extended formalism is then applied to nucleon-4He scattering, where the 3N interaction overall improves scattering phase shifts, differential cross sections and analyzing powers. Finally, the no-core shell model with continuum approach, which constitutes a unified ab-initio approach to bound and scattering states resulting from the combination of the NCSM and the NCSM/RGM, is generalized to 3N interactions and applied to the neutron-8Be system to study the impact of the continuum on the 9Be energy levels. The results demonstrate the importance of the consistent treatment of continuum states.
Theory of diffractive structure functions
International Nuclear Information System (INIS)
We discuss the connection between the dipole approach and the DIS structure functions. Particular emphasis is given to DIS diffraction. We report on current work on the NLO photon impact factor. As an application of the dipole approach in DIS diffraction, we discuss the diffractive production of jets and of charm. (author)
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-10-01
This report summarizes the work on experimental research in intermediate energy nuclear physics carried out by New Mexico State University from April 1, 1994, through March 31, 1996 under a grant from the US Department of Energy. During this period we began phasing out our programs of study of pion-nucleus and pion-nucleon interaction and of nucleon-nucleus charge-exchange reactions, which have been our major focus of the past two or three years. At the same time we continued moving in a new direction of research on studies of the internal structure of nucleons and nuclei in terms of quarks and gluons. The pion and nucleon work has been aimed at improving our understanding of the nature of pion and proton interactions in the nuclear medium and of various aspects of nuclear structure. The studies of the quark-gluon structure of nucleons are aimed at clarifying such problems as the nature of the quark sea and the relation of the nucleon spin to the spins of the quarks within the nucleon, questions which are of a very fundamental nature.
International Nuclear Information System (INIS)
This report summarizes the work on experimental research in intermediate energy nuclear physics carried out by New Mexico State University from April 1, 1994, through March 31, 1996 under a grant from the US Department of Energy. During this period we began phasing out our programs of study of pion-nucleus and pion-nucleon interaction and of nucleon-nucleus charge-exchange reactions, which have been our major focus of the past two or three years. At the same time we continued moving in a new direction of research on studies of the internal structure of nucleons and nuclei in terms of quarks and gluons. The pion and nucleon work has been aimed at improving our understanding of the nature of pion and proton interactions in the nuclear medium and of various aspects of nuclear structure. The studies of the quark-gluon structure of nucleons are aimed at clarifying such problems as the nature of the quark sea and the relation of the nucleon spin to the spins of the quarks within the nucleon, questions which are of a very fundamental nature
International Nuclear Information System (INIS)
The properties and formation are described of ?-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of ?-nucleon atoms is shown. The prospects of their use are indicated. (J.P.)
Tensor-polarized structure functions: Tensor structure of deuteron in 2020's
International Nuclear Information System (INIS)
We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones (F1, F2, g1, g2) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are b1, b2, b3, and b4 in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist- two functions are related by the Callan-Gross type relation b2 = 2xb1 in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of b1-4 from a hadron tensor W??. Second, a sum rule is explained for b1, and possible tensor-polarized distributions are discussed by using HERMES data in order to propose future experimental measurements and to compare them with theoretical models. A proposal was approved to measure b1 at the Thomas Jefferson National Accelerator Facility (JLab), so that much progress is expected for b1 in the near future. Third, formalisms of polarized proton-deuteron Drell-Yan processes are explained for probing especially tensor- polarized antiquark distributions, which were suggested by the HERMES data. The studies of the tensor-polarized structure functions will open a new era in 2020's for tensor-structure studies in terms of quark and gluon degrees of freedom, which are very different from ordinary descriptions in terms of nucleons and mesons
Excitation function of nucleon and pion elliptic flow in relativistic heavy-ion collisions
Li, B A; Sustich, A T; Zhang, B; Li, Bao-An; Sustich, Andrew T.; Zhang, Bin
1999-01-01
Within a relativistic transport (ART) model for heavy-ion collisions, we show that the recently observed characteristic change from out-of-plane to in-plane elliptic flow of protons in mid-central Au+Au collisions as the incident energy increases is consistent with the calculated results using a stiff nuclear equation of state (K=380 MeV). We have also studied the elliptic flow of pions and the transverse momentum dependence of both the nucleon and pion elliptic flow in order to gain further insight about the collision dynamics.
Energy Technology Data Exchange (ETDEWEB)
Colleen Ellis
2010-07-01
The G0 backward angle experiment, completed in Hall C of the Thomas Jefferson National Accelerator Facility (TJNAF), measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q2 = 0.22 and 0.63 (GeV/c)2. The asymmetries are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of lte 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. This was also the first measurement of the anapole moment effects in the axial-vector current at these four-momentum transfers.
Deuteron A(Q2) structure function and the neutron electric form factor
International Nuclear Information System (INIS)
We present new measurements of the deuteron A(Q2) structure function in the momentum transfer region between 1 and 18 fm-2. The accuracy of the data ranges from 2% to 6%. We investigate the sensitivity of A(Q2) to the nucleon-nucleon interaction and to the neutron electric form factor GEn. Our analysis shows that below 20 fm-2 GEn can be inferred from these data with a significantly improved accuracy. The model dependence of this analysis is discussed
Nuclear energy density functional from chiral pion-nucleon dynamics: Isovector spin-orbit terms
International Nuclear Information System (INIS)
We extend a recent calculation of the nuclear energy density functional in the systematic framework of chiral perturbation theory by computing the isovector spin-orbit terms: (?-vector?p-?-vector?n)·(J-vectorp-J-vectorn)Gso(kf)+(J-vectorp-J-vectorn)2 GJ(kf). The calculation includes the one-pion exchange Fock diagram and the iterated one-pion exchange Hartree and Fock diagrams. From these few leading order contributions in the small momentum expansion one obtains already a good equation of state of isospin-symmetric nuclear matter. We find that the parameter-free results for the (density-dependent) strength functions Gso(kf) and GJ(kf) agree fairly well with that of phenomenological Skyrme forces for densities ?>?0/10. At very low densities, a strong variation of the strength functions Gso(kf) and GJ(kf) with density sets in. This has to do with chiral singularities m?-1 and the presence of two competing small mass scales kf and m?. The novel density dependencies of Gso(kf) and GJ(kf), as predicted by our parameter-free (leading order) calculation, should be examined in nuclear structure calculations
Lepton-nucleon scattering at high energies
International Nuclear Information System (INIS)
Recent theoretical developments in the field of inelastic lepton-nucleon scattering are reviewed with emphasis on physics at HERA. Structure functions at small Bjorken-x are discussed in detail. Further topics are photoproduction of jets, the gluon densities in proton and photon, charm physics, electroweak processes and the search for new particles and interactions. (orig.)
On the photon structure function
International Nuclear Information System (INIS)
The solution of the inhomogeneous evolution equations for the parton distributions of the photon in moment space with a general Born term and three arbitrary energy parameters has been investigated. In some special cases, the general solution can be reduced to the formulas which have been obtained by the previous papers. The differences between our result and those given by the previous papers for the photon structure function are significant not only numerically, but also in singularity behavior. (author). 10 refs
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)
Neutron-star matter within the energy-density functional theory and neutron-star structure
Energy Technology Data Exchange (ETDEWEB)
Fantina, A. F.; Chamel, N.; Goriely, S. [Institut d' Astronomie et d' Astrophysique, CP226, Université Libre de Bruxelles (ULB), 1050 Brussels (Belgium); Pearson, J. M. [Dépt. de Physique, Université de Montréal, Montréal (Québec), H3C 3J7 (Canada)
2015-02-24
In this lecture, we will present some nucleonic equations of state of neutron-star matter calculated within the nuclear energy-density functional theory using generalized Skyrme functionals developed by the Brussels-Montreal collaboration. These equations of state provide a consistent description of all regions of a neutron star. The global structure of neutron stars predicted by these equations of state will be discussed in connection with recent astrophysical observations.
Neutron-star matter within the energy-density functional theory and neutron-star structure
International Nuclear Information System (INIS)
In this lecture, we will present some nucleonic equations of state of neutron-star matter calculated within the nuclear energy-density functional theory using generalized Skyrme functionals developed by the Brussels-Montreal collaboration. These equations of state provide a consistent description of all regions of a neutron star. The global structure of neutron stars predicted by these equations of state will be discussed in connection with recent astrophysical observations
Chiral perturbation theory with nucleons
Energy Technology Data Exchange (ETDEWEB)
Meissner, U.G.
1991-09-01
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, {pi}N scattering and the {sigma}-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.
First moment of the flavour octet nucleon parton distribution function using lattice QCD
International Nuclear Information System (INIS)
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle (8)?2=4 GeV2. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed by S. Dinter et. al. (2012). We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio (left angle x right angle (3))/(left angle x right angle (8)) (with left angle x right angle (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, (left angle x right angle (3))/(left angle x right angle (8))=0.39(1)(4).
Role of Vector Mesons in High-Q^2 Lepton-Nucleon Scattering
Melnitchouk, W; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
1993-01-01
The possible role played by vector mesons in inclusive deep inelastic lepton-nucleon scattering is investigated. In the context of the convolution model, we calculate self-consistently the scaling contribution to the nucleon structure function using the formalism of time-ordered perturbation theory in the infinite momentum frame. Our results indicate potentially significant effects only when the vector meson---nucleon form factor is very hard. Agreement with the experimental...
Spin and angular momentum in the nucleon
Energy Technology Data Exchange (ETDEWEB)
Franz Gross, Gilberto Ramalho, Teresa Pena
2012-05-01
Using the covariant spectator theory (CST), we present the results of a valence quark-diquark model calculation of the nucleon structure function f(x) measured in unpolarized deep inelastic scattering (DIS), and the structure functions g1(x) and g2(x) measured in DIS using polarized beams and targets. Parameters of the wave functions are adjusted to fit all the data. The fit fixes both the shape of the wave functions and the relative strength of each component. Two solutions are found that fit f(x) and g1(x), but only one of these gives a good description of g2(x). This fit requires the nucleon CST wave functions contain a large D-wave component (about 35%) and a small P-wave component (about 0.6%). The significance of these results is discussed.
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
Supramolecular Structure and Function 9
Pifat-Mrzljak, Greta
2007-01-01
The book is based on International Summer Schools on Biophysics held in Croatia which, contrary to other workshops centered mainly on one topic or technique, has very broad scope providing advanced training in areas related to biophysics. This volume is presenting papers in the field of biophysics for studying biological phenomena by using physical methods (NMR, EPR, FTIR, Mass Spectrometry, etc.) and/or concepts (predictions of protein-protein interactions, virtual ligand screening etc.). The interrelationship of supramolecular structures and there functions is enlightened by applications of principals of these physical methods in the biophysical and molecular biology context.
Conflicting Coupling of Unpaired Nucleons and the Structure of Collective Bands in Odd-Odd Nuclei
International Nuclear Information System (INIS)
The conflicting coupling of unpaired nucleons in odd-odd nuclei is discussed. A very simple explanation is suggested for the damping of the energy spacing of the lowest levels in the rotational bands in odd-odd nuclei with the 'conflicting' coupling of an odd proton and an odd neutron comparative to those of the bands based on the state of a strongly coupled particle in the neighboring odd nucleus entering the 'conflicting' configuration.
Bound-state quark and gluon contributions to structure functions in QCD
International Nuclear Information System (INIS)
One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: ''intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and ''extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic ''bound-valence'' and extrinsic ''non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs
QCD Sum Rules for Nucleon-Nucleon Interactions
Kondo, Y
1998-01-01
The QCD sum rules for spin-dependent nucleon-nucleon interactions are formulated and their physical implications are studied. The basic object of the study is the correlation function of the nucleon interpolating field, where the matrix element is taken with respect to the one-nucleon state. The dispersion integral of the correlation function around the nucleon threshold is investigated in detail. It turns out that the integral can be identified as a measure of the nucleon-nucleon interaction strength, which is proportional to the scattering length in the small scattering length limit and to one half of the effective range in the large scattering length limit. New operators must be taken into account in the OPE of the correlation function. There behavior operators do not vanish when the matrix element is taken with respect to the spin-nonaveraged one-nucleon state. The Wilson coefficients of such operators are calculated. The sum rules obtained in this manner relate the spin-dependent nucleon-nucleon interact...
First moment of the flavour octet nucleon parton distribution function using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Constantinou, Martha; Hadjiyiannakou, Kyriakos; Koutsou, Giannis [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Dinter, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Institute for Advanced Study DIAS; Jansen, Karl [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Vaquero, Alejandro [INFN, Sezione di Milano-Bicocca, Milano (Italy); Collaboration: European Twisted Mass Collaboration
2015-03-15
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle {sup (8)}{sub ?{sup 2}=4} {sub GeV{sup 2}}. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed by S. Dinter et. al. (2012). We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)}) (with left angle x right angle {sup (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, (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)})=0.39(1)(4).
Studies on regge behaviour and spin-independent and spin-dependent structure functions
Jamil, Begum Umme
2010-01-01
Deep Inelastic Scattering (DIS) experiments have provided important information on the structure of hadrons and ultimately the structure of matter and on the nature of interactions between leptons and hadrons, since the discovery of partons. Various high energy deep inelastic interactions lead to different evolution equations from which we obtain various structure functions giving information about the partons i.e. quarks and gluons involved in different scattering processes. Actually structure function is a mathematical picture of the hadron structure in the high energy region. Understanding the behaviour of the structure functions of the nucleon at low-x, where x is the Bjorken variable, is interesting both theoretically and phenomenologically. Structure functions are important inputs in many high energy processes and also important for examination of perturbative quantum chromodynamics (PQCD), the underlying dynamics of quarks and gluons. In PQCD, for high-Q2, where Q2 is the four momentum transfer in a DI...
Phenomenology of dark matter-nucleon effective interactions
Catena, Riccardo
2015-01-01
I compare the non-relativistic effective theory of one-body dark matter-nucleon interactions to current dark matter direct detection experiments and neutrino telescope observations, presenting exclusion limits on the coupling constants of the theory. In the analysis of direct detection experiments, I focus on the interference of different dark matter-nucleon interaction operators and on predictions observable at directional detectors. Interpreting neutrino telescope observations, I use new nuclear response functions recently derived through nuclear structure calculations and show that hydrogen is not the most important element in the exclusion limit calculation for the majority of the spin-dependent dark matter-nucleon interaction operators
Applications of Symmetry Breaking in Determining PDFs of the Nucleon
Cao, Fu-Guang
2011-01-01
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.
Leading nucleon production at HERA and the structure of the pion
International Nuclear Information System (INIS)
Experimental results from HERA on the production of leading neutrons in neutral current e+p collisions are reviewed. The data cover a large kinematic range from photoproduction to deep inelastic scattering. The neutrons are produced with low transverse momentum (pTL>0.2). Neutron production is studied relative to the inclusive cross section, reducing considerably the systematic error. The rate of neutrons in photoproduction is about half that expected from hadroproduction experiments. The photoproduction and hadroproduction data are otherwise in agreement and broadly in accord with particle-exchange models. There is a 20-30% rise in the rate of neutrons between photoproduction and deep inelastic scattering attributable to absorptive rescattering in the ?*p system. Aside from absorptive effects, the rate of neutron production depends only logarithmically on Q2, the virtuality of the exchanged photon, and x, the momentum fraction of the incoming proton carried by the struck quark. Factorization breaking is observed: for 0.64LL there is a weak dependence. Over the whole kinematic range from photoproduction to deep inelastic scattering, the structure function for leading neutron production is approximately given by F2LN(3)(x, Q2, xL), = A(Q2)F2(x, Q2)f(xL), where F2 is the structure function of the proton, f(xL) is the flux of neutrons and A(Q2) is an absorptive factor. The total ? ? cross section in photoproduction, ?(? ?), and the structure function of pion in deep inelastic scattering, F2?, can be extracted from the data on the assumption that pion exchange is the dominant mechanism for the production of leading neutrons. An effective flux method is introduced which avoids many theoretical uncertainties. ?(? ?) is found to be approximately one third ?(? p), violating quark counting rules which predict two thirds. The x and Q2 dependence of F2? is similar to F2. (author)
Renormalization of the nucleon currents in the nuclear medium and the nucleon-nucleon interaction
International Nuclear Information System (INIS)
The renormalization of the effective single nucleon current operators in the nuclear medium by two-nucleon exchange currents is reviewed. The exchange current operators fall into two classes: those which are implied by the nucleon-nucleon interaction, and those which are associated with transition couplings between different nonnucleonic configurations and thus model dependent. It is shown that the quenching of the axial current coupling constant and the electromagnetic isovector spin current density are mainly caused by the model dependent exchange current contributions and second order configuration mixing of the nucleon wave functions. The large enhancement of the axial charge coupling in the nuclear medium can on the other hand be ascribed to the combined effects of the well known pion exchange charge density operator and the model independent exchange current that is determined by the nucleon-nucleon interaction. ((orig.))
Hard probes of short-range nucleon-nucleon correlations
Energy Technology Data Exchange (ETDEWEB)
J. Arrington, D. W. Higinbotham, G. Rosner, M. Sargsian
2012-10-01
The strong interaction of nucleons at short distances leads to a high-momentum component to the nuclear wave function, associated with short-range correlations between nucleons. These short-range, high-momentum structures in nuclei are one of the least well understood aspects of nuclear matter, relating to strength outside of the typical mean-field approaches to calculating the structure of nuclei. While it is difficult to study these short-range components, significant progress has been made over the last decade in determining how to cleanly isolate short-range correlations in nuclei. We have moved from asking if such structures exist, to mapping out their strength in nuclei and studying their microscopic structure. A combination of several different measurements, made possible by high-luminosity and high-energy accelerators, coupled with an improved understanding of the reaction mechanism issues involved in studying these structures, has led to significant progress, and provided significant new information on the nature of these small, highly-excited structures in nuclei. We review the general issues related to short-range correlations, survey recent experiments aimed at probing these short-range structures, and lay out future possibilities to further these studies.
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)
International Nuclear Information System (INIS)
On the basis of the effective hamiltonians of (S, P, T, V, A) interactions of charged and neutral currents calculated are the differential cross sections of neutrino (antineutrino)-quark interactions with and without provision for the masses of the initial and final quarks, as well as the lepton helicity. The cross sections of deep inelastic neutrino (antineutrino)-nucleon scattering are obtained. Given are estimations of the phenomenological coupling constants of weak currents according to the available experimental data using the quark distributions accounting for deviation from scaling in deep inelastic electric production in the framework of asymptotically free gauging theories
International Nuclear Information System (INIS)
Multiplicities for the semi-inclusive production of each charge state of ?± and K± mesons in deep-inelastic scattering are presented as a function of the kinematic quantities x, Q2, z and Phperpendicularto. 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?/u? at leading-order in ?s. These results show a strong z-dependence below z ? 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 ?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 ? 0.70. This is consistent with isospin invariance below z ? 0.70. The results at high values of z show strong signs of isospin symmetry breaking.
pp Elastic Scattering in Near Forward Direction at LHC and Nucleon Structure
Islam, M M; Prokudin, A V
2005-01-01
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...
Transversity of quarks in a nucleon
Indian Academy of Sciences (India)
K. Bora; D. K. Choudhury
2003-11-01
The transversity distribution of quarks in a nucleon is one of the three fundamental distributions, that characterize nucleon’s properties in hard scattering processes at leading twist (twist 2). It measures the distribution of quark transverse spin in a nucleon polarized transverse to its (in?nite) momentum. It is a chiral-odd twist-two distribution function – gluons do not couple to it. Quarks in a nucleon/hadron are relativistically bound and transversity is a measure of the relativistic nature of bound quarks in a nucleon. In this work, we review some important aspects of this less familiar distribution function which has not been measured experimentally so far.
Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr
2015-05-29
We provide a unified ab initio description of the ^{6}Li ground state and elastic scattering of deuterium (d) on ^{4}He (?) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of ^{6}Li. The calculation reproduces the empirical binding energy of ^{6}Li, yielding an asymptotic D- to S-state ratio of the ^{6}Li wave function in the d+? configuration of -0.027, in agreement with a determination from ^{6}Li-^{4}He elastic scattering, but overestimates the excitation energy of the 3^{+} state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the ^{2}H(?,?)^{6}Li radiative capture, responsible for the big-bang nucleosynthesis of ^{6}Li. PMID:26066431
Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr
2015-05-01
We provide a unified ab initio description of the Li 6 ground state and elastic scattering of deuterium (d ) on He 4 (? ) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of Li 6 . The calculation reproduces the empirical binding energy of Li 6 , yielding an asymptotic D - to S -state ratio of the Li 6 wave function in the d +? configuration of -0.027 , in agreement with a determination from Li 6 -He 4 elastic scattering, but overestimates the excitation energy of the 3+ state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the H 2 (? ,? )Li 6 radiative capture, responsible for the big-bang nucleosynthesis of Li 6 .
Dynamical rescaling, the EMC effect and universality of hadron structure functions
International Nuclear Information System (INIS)
Data are compared on the EMC effect, with the hypothesis that the quark confinement size increases in going from a free nucleon to a nucleus. In QCD a dynamical rescaling is predicted: Q2 variation of the distribution function in a given target parallels the dependence on confinement size, R, at fixed Q2. Thus a dynamical scale invariance obtains when both R and Q2 are varied, yielding the dynamical rescaling relation F2sup(A)(x, Q2) = F2sup(N)(x, zetaQ2) where zeta > 1 is predicted for any nucleus and is a function of the confinement size. Data on 12 nuclei agree with this, implying that confinement size is governed by nuclear density. The formalism is tested by relating the pion and nucleon structure functions. (author)
Measuring spin-dependent structure functions at CEBAF
Energy Technology Data Exchange (ETDEWEB)
Schaefer, A. [Universitaet Frankfurt (Germany)
1994-04-01
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.
High x Structure Function of the Virtually Free Neutron
Cosyn, Wim
2015-01-01
The pole extrapolation method is applied for the first time to data on semi-inclusive deep-inelastic scattering off the deuteron with tagged spectator protons to extract the high Bjorken x structure function of the neutron. This approach is based on the extrapolation of the measured cross sections at different momenta of the detected spectator proton to the non-physical pole of the bound neutron in the deuteron. The advantage of the method is that it makes it possible to suppress nuclear effects in a maximally model independent way. The neutron structure functions obtained in this way demonstrate surprising x dependence at x> 0.6, indicating the possibility of a rise in the neutron to proton structure function ratio. Such a rise may indicate new dynamics in the generation of high x quarks in the nucleon. One such mechanism we discuss is the possible dominance of short-range isosinglet quark-quark correlations that can enhance the d-quark distribution in the proton resulting in d/u -> 1.
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)
The second moments of quark and gluon distribution functions in nucleon
International Nuclear Information System (INIS)
The second moments of quark and gluon distribution functions in proton are calculated on the basis of the QCD sum rule approach. The results obtained are in a good agreement with the experimental data
Electromagnetic form factors of the bound nucleon
Lu, D. H.; Tsushima, K.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia); Williams, A. G.; Saito, K
1998-01-01
We calculate electromagnetic form factors of the proton bound in specified orbits for several closed shell nuclei. The quark structure of the nucleon and the shell structure of the finite nuclei are given by the QMC model. We find that orbital electromagnetic form factors of the bound nucleon deviate significantly from those of the free nucleon.
Nucleon spin structure and pQCD frontier on the move
Pasechnik, Roman S; Teryaev, Oleg V; Solovtsova, Olga P; Khandramai, Vyacheslav L
2009-01-01
We discuss the interplay between higher orders of the perturbative QCD expansion and higher twist contributions in the analysis of recent Jefferson Lab (JLab) data on the lowest moments of spin-dependent proton and neutron structure functions $\\Gamma_1^{p,n} (Q^2)$ and Bjorken sum rule function $\\Gamma_1^{p-n}(Q^2)$ at $0.05
Energy Technology Data Exchange (ETDEWEB)
Jossten, Sylvester Johannes
2013-10-15
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.
Measurement of the spin-dependent structure function g1 of the deuteron at SLAC
International Nuclear Information System (INIS)
Deep-inelastic scattering measurements were performed at SLAC with 29 GeV polarized electrons incident on longitudinally and transversely polarized deuterons to obtain the spin-dependent structure function gd1. The high-statistics data cover the kinimatical range of xBj > 0.03 and 1 2 2. The deuteron spin-structure function gd1 and the integral ?10 gd1dx will be presented, as well as results for the fraction of nucleon helicity carried by quarks
Effective constraint algebras with structure functions
Bojowald, Martin; Brahma, Suddhasattwa
2014-01-01
This article presents the result that fluctuations and higher moments of a state do not imply quantum corrections in structure functions of constrained systems. Consequences for canonical quantum gravity, whose structure functions encode space-time structure, are discussed. In particular, deformed algebras found in models of loop quantum gravity provide reliable information even in the Planck regime.
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
International Nuclear Information System (INIS)
Excitation functions of activation cross section (cascades over continuum states included) for proton capture in heavy nuclei, namely 52130Te(p, ?)53131I, 58142Ce(p, ?)59143Pr, 70176Yb(p, ?)71177Lu, 83209Bi(p, ?)84210Po, and integrated cross sections (direct transitions to the bound states) for neutron capture in 3989Y(n, ?)3990Y, 58140Ce(n, ?)58141Ce, 82208Pb(n, ?)82209Pb, were calculated within a preequilibrium-equilibrium exciton model, using the ground-state binding energy of the even nucleon reduced for pairing, as well as within the direct-semidirect capture model. The integrated cross sections calculated within both the approaches agree reasonably well with the available experimental data, though the models differ in many aspects. As the direct-semidirect model does not treat the transitions to the continuum states, only the preequilibrium-equilibrium model is applied to the activation data. It reproduces them rather successfully. (author)
Kilin, S. Ya.; Ruffini, R.; Vereshchagin, G.
2015-06-01
An international conference in honour of the centennial of the birth of Ya.B. Zeldovich, "Subatomic Particles, Nucleons, Atoms, the Universe: Processes and Structure" was held in Minsk, Belarus on March 10-14, 2014. Scientific papers based on plenary presentations made at this conference are being published in Volumes 6 and 7, 2015 of "Astronomy Reports."
Maris, Pieter,; Vary, James P.; Navratil, Petr
2012-01-01
We solve the ab initio no-core shell model (NCSM) in the complete Nmax = 8 basis for A = 7 and A = 8 nuclei with two-nucleon and three-nucleon interactions derived within chiral effective field theory (EFT). We find that including the chiral EFT three-nucleon interaction in the Hamiltonian improves overall good agreement with experimental binding energies, excitation spectra, transitions and electromagnetic moments. We predict states that exhibit sensitivity to including the...
Nuclear effects in the structure functions
Indian Academy of Sciences (India)
E. Marco; E. Oset; S. K. Singh
2003-11-01
By using a relativistic framework and accurate nuclear spectral function the structure functions $F_{2A}$ and $F_{3A}$ of deep inelastic charged lepton and neutrino scattering are calculated in nuclei and results are presented.
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
Low x physics, deep inelastic scattering and structure functions
Energy Technology Data Exchange (ETDEWEB)
Feltesse, J.
1994-12-31
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 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 ({sigma}{sub pp} - {sigma}{sub pn})/({sigma}{sub pp} + {sigma}{sub 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 Q{sup 2} data from E143 provide a new method to determine the QCD running coupling constant {alpha}{sub 5}. Combining fixed target data from E665 and FNAL and HERA results from H1 and ZEUS, the measurements of the proton structure function F{sub 2}(x,Q{sup 2}) cover the very large kinematic range of 0.3 < Q{sup 2} < 10{sup 4} GeV{sup 2} and 2.10{sup -4} < x < 1. The steep rise of the structure function F{sub 2} with x decreasing is observed at x values below 10{sup -1} and up to Q{sup 2} values of about 1000 GeV{sup 2}. The interpretation of the F{sub 2} 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.
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
Nuclear structure function F2A: Moments Mn(F2A) and kinematics beyond x=1
International Nuclear Information System (INIS)
An analysis of the behavior of nuclear structure functions F2A at large x and their moments MnA at large n has been performed within two theoretical approaches: (i) the QCD-motivated Q2-rescaling model and (ii) the operator product expansion method within an effective meson-nucleon theory which is prompted by nuclear physics. Our theoretical estimates of the nuclear structure function at x?1 are in good agreement with existing data. The moments, derived from experimental data, are found to depend essentially on the behavior of the respective structure functions beyond x=1. A relation between the Q2-rescaling parameter ?A and nuclear averages, i.e., mean kinetic energy and chemical potential of nucleons, as well as a dependence of ?A on n are established
Functional keratin as structural platforms
Wool with up to 95% keratin by weight is a rich and pure source of proteinous biomaterial. As polymeric polyamide it exhibits high functionality through amide, carboxyl, sulfoxide, sulfide, and thiosulfide functions. Solubilized wool was transformed into keratin morphologies with the unique characte...
Toward a “structural BLAST”: Using structural relationships to infer function
Dey, Fabian; Cliff Zhang, Qiangfeng; Petrey, Donald; Honig, Barry
2013-01-01
We outline a set of strategies to infer protein function from structure. The overall approach depends on extensive use of homology modeling, the exploitation of a wide range of global and local geometric relationships between protein structures and the use of machine learning techniques. The combination of modeling with broad searches of protein structure space defines a “structural BLAST” approach to infer function with high genomic coverage. Applications are described to the prediction of p...
Functional Dynamics; 2, Syntactic Structure
Kataoka, N
1999-01-01
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...
The Jefferson Lab 12 GeV program on nucleon structure
Energy Technology Data Exchange (ETDEWEB)
Burkert, Volker D. [JLAB
2013-10-01
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.
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
Quark-parton model for the structure function W2 of the proton and neutron in their rest systems
International Nuclear Information System (INIS)
The deep-inelastic structure function W2 is calculated using the impulse approximation for mass-shell partons in the target-nucleon rest system. Bjorken scaling and the approach to scaling are shown to follow from parton kinematics in the rest system. The partons are identified as quarks and a simple harmonic-oscillator quark model is used to fit the proton and neutron structure functions down to x approx. 0.1. The neutron structure function requires an inherently non-SU(6) quark model based on relative coordinates that we argue should replace shell-model SU(6) quark models that have been used extensively
The LIGNUM functional-structural tree model
Perttunen, Jari
2009-01-01
The aim of this thesis was to construct a single tree model that builds a bridge between traditional process based tree models and detailed, three-dimensional architectural tree models. The result of the thesis, the functional-structural tree model LIGNUM, integrates both the functional and the structural aspects of woody arborescent plants in a single generic modelling framework. The thesis consists of five articles and the summary part. The first article presents the model structure of...
Relativistic effect on low-energy nucleon-deuteron scattering
Adhikari, S K; Adhikari, Sadhan K; Tomio, Lauro
1995-01-01
The relativistic effect on differential cross sections, nucleon-to-nucleon and nucleon-to-deuteron polarization transfer coefficients, and the spin correlation function, of nucleon-deuteron elastic scattering is investigated employing several three-dimensional relativistic three-body equations and several nucleon-nucleon potentials. The polarization transfer coefficients are found to be sensitive to the details of the nucleon-nucleon potentials and the relativistic dynamics employed, and prefer trinucleon models with the correct triton binding energy. (To appear in Phys. Rev. C)
Multipole decomposition of the nucleon transverse phase space
Lorcé, C
2015-01-01
We present a complete study of the leading-twist quark Wigner distributions in the nucleon, discussing both the $\\mathsf T$-even and $\\mathsf T$-odd sector, along with all the possible configurations of the quark and nucleon polarizations. We identify the basic multipole structures associated with each distribution in the transverse phase space, providing a transparent interpretation of the spin-spin and spin-orbit correlations of quarks and nucleon encoded in these functions. Projecting the multipole parametrization of the Wigner functions onto the transverse-position and the transverse-momentum spaces, we find a natural link with the corresponding multipole parametrizations for the generalized parton distributions and transverse-momentum dependent parton distributions, respectively. Finally, we show results for all the distributions in the transverse phase space, introducing a representation that allows one to visualize simultaneously the multipole structures in both the transverse-position and transverse-m...
Nuclear structure functions at low- $x$ in a holographic approach
Agozzino, LucaDipartimento di Fisica, Universitá di Catania, via S. Sofia 62, 95125 , Catania, Italy; Castorina, Paolo; Colangelo, Pietro
2014-01-01
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? ...
Granier, Thierry
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
Virtual photon structure functions and positivity constraints
International Nuclear Information System (INIS)
We study the three positivity constraints on the eight virtual photon structure functions, derived from the Cauchy-Schwarz inequality and which are, hence, model independent. The photon structure functions obtained from the simple parton model show quite different behaviors in a massive or a massless quark case, but they satisfy, in both cases, the three positivity constraints. We then discuss an inequality which holds among the unpolarized and polarized photon structure functions F1?, g1?, and WTT?, in the kinematic region ?222, where -Q2(-P2) is the mass squared of the probe (target) photon, and we examine whether this inequality is satisfied by the perturbative QCD results
Sensitivity to properties of the phi-meson in the nucleon structure in the chiral soliton model
Energy Technology Data Exchange (ETDEWEB)
Mukhopadhyay, N.C.; Zhang, L. [Rensselaer Polytechnic Inst., Troy, NY (United States)
1994-04-01
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.
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)
Structural and functional properties of designed globins
Indian Academy of Sciences (India)
Yasuhiro Isogai; Anna Ishii; Manabu Ishida; Masahiro Mukai; Motonori Ota; Ken Nishikawa; Tetsutaro Iizuka
2000-06-01
De novo design of artificial proteins is an essential approach to elucidate the principles of protein architecture and to understand specific functions of natural proteins and also to yield novel molecules for medical and industrial aims. We have designed artificial sequences of 153 amino acids to fit the main-chain framework of the sperm whale myoglobin structure based on the knowledge-based energy functions to evaluate the compatibility between protein tertiary structures and amino acid sequences. The synthesized artificial globins bind a single heme per protein molecule as designed, which show well-defined electrochemical and spectroscopic features characteristic of proteins with a low-spin heme. Redox and ligand binding reactions of the artificial heme proteins were investigated and these heme-related functions were found to vary with their structural uniqueness. Relationships between the structural and functional properties are discussed.
Structure in K--nucleon total cross sections below 1.1 GeV/c
International Nuclear Information System (INIS)
Total cross sections of K-p and K-d have been measured between 410 and 1070 MeV/c with high statistical precision. In addition to the well known ? (1520), ? (1820), and ? (1769), we confirmed the presence of the ? (1692) and the ? (1670). We have also observed several structures which could be Y* resonances: ? (1646), ? (1735), ? (1583), ? (1608), ? (1633), and ? (1715)
Polarized deuteron structure functions at small x
International Nuclear Information System (INIS)
We investigate shadowing corrections to the polarized deuteron structure functions gd1 and b1. In the kinematic domain of current fixed target experiments we observe that shadowing effects in gd1 are approximately twice as large as for the unpolarized structure function Fd2. Furthermore, we find that b1 is surprisingly large at x<0.1 and receives dominant contributions from coherent double scattering. (orig.)
Neutrino Production of a Charmed Meson and the Transverse Spin Structure of the Nucleon.
Pire, B; Szymanowski, L
2015-08-28
We calculate the amplitude for exclusive neutrino production of a charmed meson on an unpolarized target in the collinear QCD approach, where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We demonstrate that the transversity chiral odd GPDs contribute to the transverse cross section if the hard amplitude is calculated up to order m_{c}/Q. We show how to access these GPDs through the azimuthal dependence of the ?N??^{-}D^{+}N differential cross section. PMID:26371643
Spectral Density Functionals for Electronic Structure Calculations
Savrasov, S.Y.; G. Kotliar
2003-01-01
We introduce a spectral density functional theory which can be used to compute energetics and spectra of real strongly--correlated materials using methods, algorithms and computer programs of the electronic structure theory of solids. The approach considers the total free energy of a system as a functional of a local electronic Green function which is probed in the region of interest. Since we have a variety of notions of locality in our formulation, our method is manifestly...
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
Quasi-elastic electron scattering and nucleon-nucleon correlations
International Nuclear Information System (INIS)
In this contribution we briefly review some recent results, illustrating the possibilities of obtaining information on short-range corelations (SRC) by the quasi-elastic (QE) electron scattering, where the reaction mechanism is expected to be governed mainly by one-body electromagnetic nucleon currents and multi-nucleon final states can be excited. The paper is organized as follows: In Sec. 2 the results of recent experiments on inclusive 4He(e,e') and exclusive 4He(e,e'p)3H reactions performed at Saclay with the aim of checking the one-body nature of the reaction mechanism, are presented; in Sec. 3, the y-scaling analysis of SLAC inclusive cross sections for complex nuclei and the extraction of the nucleon momentum distribution will be illustrated; in Sec. 4 the effects of SRC on the QE response function is analyzed in terms of different models of the nucleon Spectral Function. (orig.)
Structure functions in the chiral bag model
International Nuclear Information System (INIS)
We calculate the structure functions of an isoscalar nuclear target for the deep inelastic scattering by leptons in an extended version of the chiral bag model which incorporates the qanti q structure of the pions in the cloud. Bjorken scaling and Regge behavior are satisfied. The model calculation reproduces the low-x behavior of the data but fails to explain the medium- to large-x behavior. Evolution of the quark structure functions seem inevitable to attempt a connection between the low-energy models and the high-energy behavior of quantum chromodynamics. (orig.)
Dressing the cloudy bag model: Second-order nucleon-nucleon potential
International Nuclear Information System (INIS)
We calculate the second-order static physical nucleon-nucleon potential resulting from applying a unitary dressing transformation to the trilinear pion-nucleon interaction with cloudy bag model vertex functions. We find that for two physical nucleons separated by any distance greater than twice the bag radius this potential is exactly the usual one-pion exchange potential modified in strength by a factor 1.05 for a bag of radius 0.7 fm
Dressing the cloudy bag model: Second-order nucleon-nucleon potential
Energy Technology Data Exchange (ETDEWEB)
Hearn, D.J.; McMillan, M.; Raskin, A.
1983-12-01
We calculate the second-order static physical nucleon-nucleon potential resulting from applying a unitary dressing transformation to the trilinear pion-nucleon interaction with cloudy bag model vertex functions. We find that for two physical nucleons separated by any distance greater than twice the bag radius this potential is exactly the usual one-pion exchange potential modified in strength by a factor 1.05 for a bag of radius 0.7 fm.
Magnetism and Structure in Functional Materials
Planes, Antoni; Saxena, Avadh
2005-01-01
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.
Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order
Energy Technology Data Exchange (ETDEWEB)
Epelbaum, E.; Krebs, H. [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany); Meissner, U.G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Forschungszentrum Juelich, Institut fuer Kernphysik, Institute for Advanced Simulation, and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, JARA - High Performance Computing, Juelich (Germany)
2015-05-15
We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of previous works (Nucl. Phys. A 747, 362 (2005) and Phys. Rev. C 68, 041001 (2003)) is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in (Nucl. Phys. A 747, 362 (2005)) to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c{sub i} and d{sub i} determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also employ a simple approach for estimating the theoretical uncertainty in few-nucleon calculations from the truncation of the chiral expansion that replaces previous reliance on cutoff variation. (orig.)
Nucleon-nucleon interaction in constituent quark models
International Nuclear Information System (INIS)
By using the chiral quark model and the quark delocalization colour screening model, the phase shifts of nucleon-nucleon scattering for high partial waves are studied. The results of both the models are almost equivalent. None of the quark models used have found any resonance-like structure in 3F2, 3F3, 3F4 and 3H4 partial waves. (authors)
A NEW METHOD FOR EXTRACTING SPIN-DEPENDENT NEUTRON STRUCTURE FUNCTIONS FROM NUCLEAR DATA
Energy Technology Data Exchange (ETDEWEB)
Kahn, Y.F.; Melnitchouk, W.
2009-01-01
High-energy electrons are currently the best probes of the internal structure of nucleons (protons and neutrons). By collecting data on electrons scattering off light nuclei, such as deuterium and helium, one can extract structure functions (SFs), which encode information about the quarks that make up the nucleon. Spin-dependent SFs, which depend on the relative polarization of the electron beam and the target nucleus, encode quark spins. Proton SFs can be measured directly from electron-proton scattering, but those of the neutron must be extracted from proton data and deuterium or helium-3 data because free neutron targets do not exist. At present, there is no reliable method for accurately determining spin-dependent neutron SFs in the low-momentum-transfer regime, where nucleon resonances are prominent and the functions are not smooth. The focus of this study was to develop a new method for extracting spin-dependent neutron SFs from nuclear data. An approximate convolution formula for nuclear SFs reduces the problem to an integral equation, for which a recursive solution method was designed. The method was then applied to recent data from proton and deuterium scattering experiments to perform a preliminary extraction of spin-dependent neutron SFs in the resonance region. The extraction method was found to reliably converge for arbitrary test functions, and the validity of the extraction from data was verifi ed using a Bjorken integral, which relates integrals of SFs to a known quantity. This new information on neutron structure could be used to assess quark-hadron duality for the neutron, which requires detailed knowledge of SFs in all kinematic regimes.
Measurement of the neutron F2 structure function via spectator tagging with CLAS
Baillie, N.; S. Tkachenko; Christy, M. E.(Hampton University, 23668, Hampton, VA, USA); Fenker, H.; Griffioen, K.A.; Kuhn, S. E.; Melnitchouk, W.; Tvaskis, V; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Amaryan, M. J.; Briscoe, W. J.; Brooks, W. K.; Carman, D. S.
2011-01-01
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 a...
International Nuclear Information System (INIS)
Data from an exposure of the BEBC bubble chamber filled with deuterium to neutrino and antineutrino wide band beams have been used to extract the x dependence of the structure functions for scattering on protons and neutrons and the fractional momentum distributions of the valence quarks and the antiquarks of different flavours. The difference F2sup(n) - F2sup(p) is compared with recent data from high energy ?D scattering. A result is also obtained on the sum rule giving the difference between the number of up and down quarks in the nucleon. (orig.)
Husimi distribution for nucleon tomography
Hatta, Yoshitaka
2015-01-01
We define the QCD Husimi distribution as the phase space distribution of partons inside the nucleon. Compared to the more well-known Wigner distribution, the Husimi distribution is better behaved and positive. It thus allows for a probabilistic interpretation and can be used to define the `entropy' of the nucleon as a measure of complexity of the partonic structure. A possible connection to the Color Glass Condensate approach at small-$x$ is also discussed.
Nucleon form factors, generalized parton distributions and quark angular momentum
International Nuclear Information System (INIS)
We extract the individual contributions from u and d quarks to the Dirac and Pauli form factors of the proton, after a critical examination of the available measurements of electromagnetic nucleon form factors. From this data we determine generalized parton distributions for valence quarks, assuming a particular form for their functional dependence. The result allows us to study various aspects of nucleon structure in the valence region. In particular, we evaluate Ji's sum rule and estimate the total angular momentum carried by valence quarks at the scale ?=2 GeV to be Juv=0.230+0.009-0.024 and Jdv=-0.004+0.010-0.016.
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)
International Nuclear Information System (INIS)
We discover an inner structure of QED while the gauge potential is decomposed into two orthogonal components. Based on this, the Lagrangian of the electron-photon system is expanded to a new form and by the general method of field theory, the gauge invariant spin and orbital angular momentum operators of the electron and photon are naturally obtained from Noether's theorem. Our method, which can be generalized to the non-Abelian systems to investigate the inner structure of QCD, provides a new perspective to look on the nucleon spin crisis and opens a window into a strict and systematic resolution of this long-standing problem.
Anomalous evolution of nonsinglet structure functions
International Nuclear Information System (INIS)
We review a formalism that includes the effects of nonperturbative U(1) symmetry breaking on the QCD evolution of nonsinglet structure functions. We show that a strong scale dependence is generated in an intermediate energy range 0.522 for all values of x. We show that this explains naturally the observed violation of the Gottfried sum, and allows a determination of the shape of the nonsinglet structure function, in excellent agreement with experiment. We argue that these effects may affect the determination of ?s, from deep-inelastic scattering. ((orig.))
Coherence effects in deuteron spin structure functions
Energy Technology Data Exchange (ETDEWEB)
Edelmann, J.; Piller, G.; Weise, W. [Physik Department, Institut fuer Theoretische Physik, Technische Universitaet Muenchen, Garching (Germany)
1998-05-01
We investigate coherence effects in the deuteron spin structure functions g{sub 1}{sup d} and b{sub 1}. In the kinematic domain of current fixed target experiments we observe that shadowing effects in g{sub 1}{sup d} are approximately twice as large as for the unpolarized structure function F{sub 2}{sup d}. Furthermore, we find that b{sub 1} is large at x<0.1 and receives dominant contributions from coherent double scattering. (author) 13 refs, 2 figs
Structure Functions of Unstable Lithium Isotopes
Saito, K; Ueda, M.; Tsushima, K.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
2001-01-01
We study both the spin-average and spin-dependent structure functions of the lithium isotopes, $^{6-11}$Li, which could be measured at RIKEN and other nuclear facilities in the future. It is found that the light-cone momentum distribution of the valence neutron in the halo of $^{11}$Li is very sharp and symmetric around y = 1, because of the weak binding. The EMC ratios for Li isotopes are then calculated. We study the possibility of extracting the neutron structure function...
On statistical methods of structure function extraction
Sevbitov, S. N.; Shishkina, T. V.; Solovtsov, I. L.
2007-01-01
Several methods of statistical analysis are proposed and analyzed in application for a specific task -- extraction of the structure functions from the cross sections of deep inelastic interactions of any type. We formulate the method based on the orthogonal weight functions and on an optimization procedure of errors minimization as well as methods underlying common $\\chi^2$ minimization. Effectiveness of these methods usage is analyzed by comparison of the statistical parame...
First measurement of the gluon polarisation in the nucleon using D mesons at COMPASS
von Hodenberg, Martin
2005-01-01
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...
Nucleon-Nucleon Interactions from the Quark Model
Downum, Clark; Barnes, Ted; Swanson, Eric; Vidana, Isaac
2010-01-01
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.
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.
Family-changes In Structure And Functions
Sambhaji R. Warangule Patil
2013-01-01
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 ...
QCD structure of W boson and electron structure function
Energy Technology Data Exchange (ETDEWEB)
Slominski, W.; Szwed, J. [Institute of Computer Science, Jagiellonian University, Cracow (Poland)
1997-06-01
The QCD structure of the W boson is constructed and compared with that of the photon. A new concept of the electron structure function is also defined. 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{sup 2} behaviour of the parton densities is observed. Possible applications with clear manifestation of ``resolved`` photon and weak bosons are discussed. (author) 9 refs, 6 figs
Generalized functions, convergence structures, and their applications
Pap, Endre; Pilipovi?, Stevan; Vladimirov, Vasilij; International Conference "Generalized functions, convergence structures and their applications" (GFCA-87)
1988-01-01
This Proceedings consists of a collection of papers presented at the International Conference "Generalized functions, convergence structures and their applications" held from June 23-27, 1987 in Dubrovnik, Yugoslavia (GFCA-87): 71 participants from 21 countr~es from allover the world took part in the Conference. Proceedings reflects the work of the Conference. Plenary lectures of J. Burzyk, J. F. Colombeau, W. Gahler, H. Keiter, H. Komatsu, B. Stankovic, H. G. Tillman, V. S. Vladimirov provide an up-to-date account of the cur rent state of the subject. All these lectures, except H. G. Tillman's, are published in this volume. The published communications give the contemporary problems and achievements in the theory of generalized functions, in the theory of convergence structures and in their applications, specially in the theory of partial differential equations and in the mathematical physics. New approaches to the theory of generalized functions are presented, moti vated by concrete problems of applicat...
Nucleon-pion-state contributions in the determination of the nucleon axial charge
Bar, Oliver
2015-01-01
The nucleon-pion-state contributions to QCD 2- and 3-point functions used in the calculation of the nucleon axial charge are studied in chiral perturbation theory. For sufficiently small quark masses and large volumes the nucleon-pion states are expected to have smaller total energy than the single-particle excited states. To leading order in chiral perturbation theory the results do not depend on low-energy constants associated with the interpolating nucleon fields and apply to local as well as smeared interpolators. The nucleon-pion-state contribution is found to be at the few percent level.
Nucleon Magnetic Moments and Electric Polarizabilities
Detmold, William; Tiburzi, Brian C.; Walker-Loud, Andre
2010-01-01
Electromagnetic properties of the nucleon are explored with lattice QCD using a novel technique. Focusing on background electric fields, we show how the electric polarizability can be extracted from nucleon correlation functions. A crucial step concerns addressing contributions from the magnetic moment, which affects the relativistic propagation of nucleons in electric fields. By properly handing these contributions, we can determine both magnetic moments and electric polari...
Avakian, H; Hasch, D; Schweitzer, P
2012-01-01
The three-dimensional nucleon structure is central to many theoretical and experimental activities, and research in this field has seen many advances in the last two decades, addressing fundamental questions such as the orbital motion of quarks and gluons inside the nucleons, their spatial distribution, and the correlation between spin and intrinsic motion. A real three-dimensional imaging of the nucleon as a composite object, both in momentum and coordinate space, is slowly emerging. This book presents lectures and seminars from the Enrico Fermi School: Three-Dimensional Partonic Structure of the Nucleon, held in Varenna, Italy, in June and July 2011. The topics covered include: partonic distributions, fragmentation functions and factorization in QCD; theory of transverse momentum dependent partonic distributions (TMDs) and generalized partonic distributions (GPDs); experimental methods in studies of hard scattering processes; extraction of TMDs and GPDs from data; analysis tools for azimuthal asymmetries; ...
Measurement of the neutron F2 structure function via spectator tagging with CLAS
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
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.
The triton with long-range chiral N3LO three nucleon forces
Skibinski, R; Topolnicki, K; Witala, H; Epelbaum, E; Gloeckle, W; Krebs, H; Nogga, A; Kamada, H
2011-01-01
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.
The extraction of the spin structure function, g2 (and g1) at low Bjorken x
Energy Technology Data Exchange (ETDEWEB)
Ndukum, Luwani Z. [Mississippi State University
2015-08-01
The Spin Asymmetries of the Nucleon Experiment (SANE) used the Continuous Electron Beam Accelerator Facility at Jefferson Laboratory in Newport News, VA to investigate the spin structure of the proton. The experiment measured inclusive double polarization electron asymmetries using a polarized electron beam, scattered off a solid polarized ammonia target with target polarization aligned longitudinal and near transverse to the electron beam, allowing the extraction of the spin asymmetries A1 and A2, and spin structure functions g1 and g2. Polarized electrons of energies of 4.7 and 5.9 GeV were used. The scattered electrons were detected by a novel, non-magnetic array of detectors observing a four-momentum transfer range of 2.5 to 6.5 GeV*V. This document addresses the extraction of the spin asymmetries and spin structure functions, with a focus on spin structure function, g2 (and g1) at low Bjorken x. The spin structure functions were measured as a function of x and W in four Q square bins. A full understanding of the low x region is necessary to get clean results for SANE and extend our understanding of the kinematic region at low x.
K(+) channels: function-structural overview.
González, Carlos; Baez-Nieto, David; Valencia, Ignacio; Oyarzún, Ingrid; Rojas, Patricio; Naranjo, David; Latorre, Ramón
2012-07-01
Potassium channels are particularly important in determining the shape and duration of the action potential, controlling the membrane potential, modulating hormone secretion, epithelial function and, in the case of those K(+) channels activated by Ca(2+), damping excitatory signals. The multiplicity of roles played by K(+) channels is only possible to their mammoth diversity that includes at present 70 K(+) channels encoding genes in mammals. Today, thanks to the use of cloning, mutagenesis, and the more recent structural studies using x-ray crystallography, we are in a unique position to understand the origins of the enormous diversity of this superfamily of ion channels, the roles they play in different cell types, and the relations that exist between structure and function. With the exception of two-pore K(+) channels that are dimers, voltage-dependent K(+) channels are tetrameric assemblies and share an extremely well conserved pore region, in which the ion-selectivity filter resides. In the present overview, we discuss in the function, localization, and the relations between function and structure of the five different subfamilies of K(+) channels: (a) inward rectifiers, Kir; (b) four transmembrane segments-2 pores, K2P; (c) voltage-gated, Kv; (d) the Slo family; and (e) Ca(2+)-activated SK family, SKCa. PMID:23723034
Amino Acid Correlation Functions in Protein Structures.
Kržišnik, Klemen; Urbic, Tomaz
2015-01-01
Understanding the spatial folding of proteins from their amino acid sequences has an enormous potential in contemporary life sciences. The ability to predict secondary and tertiary structures from primary ones through the use of computers will enable a much faster and more efficient discovery of organic substances with therapeutic or otherwise bioactive potential, largely eliminating the need for synthesis and testing of large numbers of organic substances for physiological effects. Our manuscript presents an application of correlation function analysis, usually used to describe properties of liquids, to protein structures in order to elucidate statistically favored distances among amino acids. Pairwise distribution functions were calculated between C-alpha atoms of 20 amino acids in a large ensemble of Protein Data Bank structures. The correlation functions show characteristic distances in amino acid interactions. Different propensities for forming various secondary structure elements among all 210 possible amino acid pairs have been visualized and some have been interpreted. Notably, we found helices to be surprisingly common among certain pairs. PMID:26454591
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)
The spin dependent structure function g{sub 1} of the deuteron and the proton
Energy Technology Data Exchange (ETDEWEB)
Klostermann, L.
1995-02-27
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).
Levon, A I
2011-01-01
Conflicting coupling of unpaired nucleons in the odd-odd nuclei is discussed. A very simple explanation is suggested for the damping of the energy spacing of the lowest levels in the rotational bands in the odd-odd nuclei in the case of a "conflicting" coupling of the odd proton and neutron comparative to those of the bands based on the state of the strongly-coupled particle in the neighbouring odd nuclei entering the "conflicting" configuration.
Hupin, Guillaume; Navrátil, Petr
2014-01-01
Prototype for the study of weakly bound projectiles colliding on stable targets, the scattering of deuterium ($d$) on $^4$He ($\\alpha$) is an important milestone in the search for a fundamental understanding of low-energy reactions. At the same time, it is also important for its role in the Big-bang nucleosynthesis of $^6$Li and applications in the characterization of deuterium impurities in materials. We present the first unified {\\em ab initio} study of the $^6$Li ground state and $d$-$^4$He elastic scattering using two- and three-nucleon forces derived within the framework of chiral effective field theory. The six-nucleon bound-state and scattering observables are calculated by means of the no-core shell model with continuum. %and are compared to available experimental data. We analyze the influence of the dynamic polarization of the deuterium and of the chiral three-nucleon force, and examine the role of the continuum degrees of freedom in shaping the low-lying spectrum of $^6$Li. We find that the adopted...
Quark sea asymmetry of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Mirez, Carlos; Tomio, Lauro [Instituto de Fisica Teorica, Universidade Estadual Paulista-Unesp, Rua Dr. Bento Teobaldo Ferraz, 271, Barra-Funda, 01140-070, Sao Paulo, SP (Brazil); Trevisan, L.A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Frederico, T. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, CTA, 12228-900, Sao Jose dos Campos, SP (Brazil)
2010-02-15
The light anti-quark and quark distribution in the proton, as well as the neutron to proton ratio of the structure functions, extracted from experimental data, are well fitted by a statistical model of linear-confined quarks. The parameters of the model are given by a temperature, which is adjusted by the Gottfried sum-rule violation, and two chemical potentials given by the corresponding up (u) and down (d) quark normalizations in the nucleon. The quark energy levels are generated by a relativistic linear-confined scalar plus vector potential.
Phosphatidylinositol 4-kinases: Function, structure, and inhibition.
Boura, Evzen; Nencka, Radim
2015-10-01
The phosphatidylinositol 4-kinases (PI4Ks) synthesize phosphatidylinositol 4-phosphate (PI4P), a key member of the phosphoinositide family. PI4P defines the membranes of Golgi and trans-Golgi network (TGN) and regulates trafficking to and from the Golgi. Humans have two type II PI4Ks (? and ?) and two type III enzymes (? and ?). Recently, the crystal structures were solved for both type II and type III kinase revealing atomic details of their function. Importantly, the type III PI4Ks are hijacked by +RNA viruses to create so-called membranous web, an extensively phosphorylated and modified membrane system dedicated to their replication. Therefore, selective and potent inhibitors of PI4Ks have been developed as potential antiviral agents. Here we focus on the structure and function of PI4Ks and their potential in human medicine. PMID:26183104
Dynamic versus Static Hadronic Structure Functions
International Nuclear Information System (INIS)
'Static' structure functions are the probabilistic distributions computed from the square of the light-front wavefunctions of the target hadron. In contrast, the 'dynamic' structure functions measured in deep inelastic lepton-hadron scattering include the effects of rescattering associated with the Wilson line. Initial- and final-state rescattering, neglected in the parton model, can have a profound effect in QCD hard-scattering reactions, producing single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam-Tung relation in Drell-Yan reactions, nuclear shadowing, and non-universal nuclear antishadowing-novel leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also review how 'direct' higher-twist processes - where a proton is produced in the hard subprocess itself - can explain the anomalous proton-to-pion ratio seen in high centrality heavy ion collisions.
Narrow structure in the excitation function of ? photoproduction off the neutron.
Werthmüller, D; Witthauer, L; Keshelashvili, I; Aguar-Bartolomé, 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; Käser, 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
2013-12-01
The photoproduction of ? mesons off nucleons bound in 2H and 3He 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 ??2? and ??3?0 decays and the recoil nucleons were detected with an almost 4? 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 ?n?n?. 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±5)??MeV and ?=(30±15)??MeV. For the first time precise results for the angular dependence of this structure have been extracted. PMID:24476257
Tkachenko, S; Kuhn, S E; Zhang, J; Arrington, J; Bosted, P; Bültmann, S; Christy, M E; Fenker, H; Griffioen, K A; Kalantarians, N; Keppel, C E; Melnitchouk, W; Tvaskis, V; Adhikari, K P; Aghasyan, M; Amaryan, M J; Pereira, S Anefalos; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Cole, P L; Contalbrigo, M; Cortes, O; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fleming, J A; Garillon, B; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gothe, R W; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Hicks, K; Ho, D; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jo, H S; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Koirala, S; Kubarovsky, V; Kuleshov, S V; Lenisa, P; Lewis, S; Livingston, K; Lu, H; MacCormick, M; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Mineeva, T; Mirazita, M; Mokeev, V; Montgomery, R A; Moutarde, H; Camacho, C Munoz; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Park, K; Pasyuk, E; Phillips, J J; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Puckett, A J R; Rimal, D; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Schott, D; Schumacher, R A; Seder, E; Senderovich, I; Sharabian, Y G; Simonyan, A; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S; Stepanyan, S S; Strauch, S; Tang, W; Ungaro, M; Vlassov, A V; Voskanyan, H; Voutier, E; Walford, N K; Watts, D; Wei, X; Weinstein, L B; Wood, M H; Zana, L; Zonta, I
2014-01-01
Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. The Barely Off-shell Nucleon Structure (BONuS) experiment at Jefferson Lab measured the inelastic electron deuteron scattering cross section, tagging spectator protons in coincidence with the scattered electrons. This method reduces nuclear binding uncertainties significantly and has allowed for the first time a (nearly) model independent extraction of the neutron structure function. A novel compact radial time projection chamber was built to detect protons with momentum between 70 and 150 MeV/c. For the extraction of the free neutron structure function $F_{2n}$, spectator protons at backward angle and with...
Function and Structure in Retinal Transplants
Adolph, Alan R.; Zucker, Charles L.; Ehinger, Berndt; Bergström, Anders
1994-01-01
Embryonic mammalian donor retina transplanted into the subretinal space of a mature host develops into a graft with wellorganized, but atypical retinal structure. We tested the effect of this organization on rabbitto-rabbit graft functional properties, isolating the graft to avoid contamination of graft responses by host retinal activity. Transient ON or ON-OFF spike-like responses and local electroretinograms (L-ERGs) were recorded simultaneously via a single el...
Theoretical analysis of polarized structure functions
Energy Technology Data Exchange (ETDEWEB)
Altarelli, G. [CERN Theoretical Physics Division, Geneva (European Organization for Nuclear Research (CERN)); Ball, R.D. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Forte, S. [INFN, Sezione di Torino, Torino (Italy); Ridolfi, G. [INFN, Sezione di Genova, Genova (Italy)
1998-05-01
We review the analysis of polarized structure function data using perturbative QCD and NLO We use the most recent experimental data to obtain updated results for polarized parton distributions, first moments and the strong coupling. We also discuss several theoretical issues involving in this analysis and in the interpretation of its results. Finally, we compare our results with other similar analyses in the recent literature. (author) 67 refs, 5 figs, 3 tabs
Supramolecular chemistry: Functional structures on the mesoscale
Nguyen, SonBinh T.; Gin, Douglas L.; Hupp, Joseph T.; Zhang, Xi
2001-01-01
Supramolecular chemistry deals with the chemistry and collective behavior of organized ensembles of molecules. In this so-called mesoscale regime, molecular building blocks are organized into longer-range order and higher-order functional structures via comparatively weak forces. As one of the modern frontiers in chemistry, supramolecular chemistry heralds many promises that range from biocompatible materials and biomimetic catalysts to sensors and nanoscale fabrication of electronic devices.
Influenza Virus Neuraminidase: Structure and Function
Shtyrya, Y.A.; Mochalova, L.V.; Bovin, N. V.
2009-01-01
The structure of the influenza virus neuraminidases, the spatial organization of their active site, the mechanism of carbohydrate chains desialylation by neuraminidase, and its role in the influenza virus function at different stages of the viral infectious cycle are considered in this review. Data on the neuraminidase substrate specificity and different approaches in studying the activity of this enzyme are summarized. In addition, data on neuraminidase inhibitors (as antivirals) are provide...
International Nuclear Information System (INIS)
The structure of the neutron rich light nuclei 11Be and 10Li has been investigated by means of one nucleon transfer reactions. The experiments have been carried out at GANIL in inverse kinematics using 11Be secondary beams. The 11Be(p,d)10Be reaction bas been studied at 35.3 MeV/u. The 10Be ejectiles were analyzed by the spectrometer SPEG, and coincident deuterons were detected in the position sensitive silicon detector CHARISSA. Transfer cross sections to 0+1 and 2+1, states in 10Be were measured up to ?CM = 16 deg. and compared to DWBA and CRC predictions. The effects of neutron-cure couplings on reaction form factors have been studied by solving coupled equations in the framework of a vibrational model. It is shown that the rate of core excitation 10Be2+ in the 11Begs wave function is overestimated by a standard analysis with form factors given by the usual Separation Energy prescription. The former model predicts a rate of core excitation of 16% and leads to theoretical cross sections which are in good agreement with the experimental data. The aim of the 11Be(d,3He)10Li experiment, realized at 37 MeV/u, was to measure the distribution of the 2s neutron strength in the unbound nucleus 10Li. The energy spectrum was deduced from the 3He energy and angle measured by the silicon strip detector array MUST. An asymmetric peak is clearly observed near the threshold, with a maximum at -Sn = 130 keV. This constitutes a direct proof of the inversion of 2s and 1p1/2 shells in 10Li, which was until now a controversial question in spite of many experimental efforts. On the other band the analysis of the 11Be(d,t)10Be reaction studied in the same experiment confirms the results obtained in the 11Be(p,d)10Be reaction concerning the 11Begs structure. This work shows the interest and feasibility of studies of the shell properties of exotic nuclei using transfer reactions induced by radioactive beams and constitutes the beginning of a program devoted to this kind of experiment. (author)
The Role of Strange and Charm Quarks in the Nucleon Spin Structure Function
Steffens, F. M.; Thomas, A.W.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, The University of Adelaide, Australia)
1995-01-01
We perform an analysis of the relation between the factorization scale and the masses of the quarks in the calculation of the hard gluon coefficient in polarized deep inelastic scattering. Particular attention is paid to the role of strange and charm quarks at finite momentum transfer. It is found that for the momentum transfer of the present experiments, the contribution from the charm quark is significant.
Pion-nucleon and kaon-nucleon scattering lengths in QCD sum rules
International Nuclear Information System (INIS)
The pion-nucleon and kaon-nucleon scattering lengths are studied in the QCD sum rule. We show that the leading and next-to-leading order terms of OPE give rise to the Tomozawa-Weinberg and sigma terms, respectively. We also show that in the kaon-nucleon system the ?(1405) contribution has to be subtracted from the OPE side in order to obtain the scattering length. The odd components of the T-matrices are in agreement with the experimental values not only in the pion-nucleon channel but also in the kaon-nucleon channel after the ?(1405) contribution subtracted. The even components disagree with the experimental values in the pion-nucleon channel, which is similar to the situation in the PCAC-plus-current-algebra approach at the Weinberg point. We speculate that this discrepancy should be explained by the continuum contribution in the spectral function above the pion-nucleon threshold. (author)
Structural and functional neuroimaging in intractable epilepsy
Directory of Open Access Journals (Sweden)
Chinchure Swati
2010-01-01
Full Text Available Medical management remains unsatisfactory in about a third of patients with epilepsy and some of them are candidates for resective epilepsy surgery. Structural and functional neuroimaging plays an important role in the identification of the precise cortical region responsible for seizures and is very crucial for a good surgical outcome. Furthermore, identification of eloquent cortical areas near the region to be resected is essential to avoid postoperative neurologic deficit. The magnetic resonance imaging (MRI protocol for epilepsy can be individually tailored depending on the seizure semiology and possibly electroencephalography. New MRI techniques demonstrate the structure of the brain in fine detail, help in understanding the underlying pathology, and demonstrate functional activity of the brain with high spatial and temporal resolution. Metabolic imaging techniques, such as positron emission tomography (PET and single photon emission tomography (SPECT visualize metabolic alterations of the brain in the ictal and interictal states. In MR-negative epilepsy patients, these techniques may have localizing value. The proper use and interpretation of the findings provided by these new technologies is crucial. In this review article, we discuss various conventional and advanced MRI techniques, interpretation of various findings, and the role of functional imaging modalities, such as functional MRI, PET, and SPECT in the localization of epileptogenic substrate as well as for understanding the pathophysiology, propagation, and neurochemical correlates of epilepsy.
Spin observables in nucleon-nucleus scattering
Energy Technology Data Exchange (ETDEWEB)
Moss, J.M.
1982-01-01
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.
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
Tensor optimized shell model with bare nucleon-nucleon interaction for 4He
Myo, Takayuki; Ikeda, Kiyomi
2009-01-01
The pion exchange between nucleons generates a strong tensor interaction, which provides large attractive contribution for the binding energy of nucleus. This non-central tensor interaction is difficult to handle in the shell model framework, which hinders full understanding of nuclear structure. We develop the tensor optimized shell model (TOSM) for the strong tensor interaction and now we are able to use bare nucleon-nucleon interaction with the help of the unitary correlation operator method (UCOM) for the short range hard core. We adopt the nucleon-nucleon interaction, AV8', and calculate explicitly the ground state of 4He and make a detailed comparison with rigorous few-body model calculations. We show a large amount of success of the tensor optimized shell model with bare nucleon-nucleon interaction for 4He.
Nucleon momentum and density distributions of nuclei
International Nuclear Information System (INIS)
In the framework of recently suggested density coherent fluctuations model the nucleon momentum and density distributions are examined. Nucleon momentum and density distributions are expressed in terms of the fluctuation's function, experimentally obtainable from the elastic electron-nuclei scattering. (author)
On the electromagnetic polarisabilities of the nucleon
International Nuclear Information System (INIS)
The dynamic electric and magnetic polarisabilities of the nucleon are calculated taking the photon-nucleon resonance vertex-function ambiguity parameters into account. The annihilation channel in the Compton scattering amplitude is also evaluated from the chiral effective Lagrangian. It is found that the electric and magnetic polarisabilities of the proton are of the same order of magnitude. (author)
A study of the ground-state energy of 4He with nucleon-nucleon potentials
International Nuclear Information System (INIS)
Ground-state properties are evaluated for the finite nucleus 4He starting from realistic nucleon-nucleon interactions within the framework of the Green's function approach. For the sake of comparison, the same calculations are performed using the Brueckner-Hartree-Fock approximation. For that purpose four high-quality modern nucleon-nucleon interactions represented in momentum space are employed: the Argonne V18, CD-Bonn, Bonn A and N3LO potentials. In these potentials, the effects of charge dependence are taken into account. Additional binding energy is obtained from the inclusion of the hole-hole scattering term within the framework of the Green function approach. It has been shown that the Green function results agree well with the results obtained by accurate methods for few-nucleon systems such as the Faddeev-Yakubovsky calculation. In this study, a comparison of the calculated ground-state energies, obtained by using the Green function approach and different nucleon-nucleon potentials, with experimental values is carried out. The results show good agreement between the calculated values and the experimental ones. - Highlights: ? We present ground-state energies of the helium nucleus. ? We consider four high-quality modern nucleon-nucleon potentials. ? It is shown that the Green function approach gives quite good results.
Polymer nanocomposites: structure, interaction, and functionality
Keledi, Gergely; Hári, József; Pukánszky, Béla
2012-03-01
This feature article discusses the main factors determining the properties of polymer nanocomposites with special attention paid to structure and interactions. Usually more complicated structure develops in nanocomposites than in traditional particulate filled polymers, and that is especially valid for composites prepared from plate-like nanofillers. Besides the usually assumed exfoliated/intercalated morphology, i.e. individual platelets and tactoids, such nanocomposites often contain large particles, and a network structure developing at large extent of exfoliation. Aggregation and orientation are the most important structural phenomena in nanotube or nanofiber reinforced composites, and ag-gregation is a major problem also in composites prepared with spherical particles. The surface characteristics of nanofillers and interactions are rarely determined or known; the related problems are discussed in the paper in detail. The surface of these reinforcements is modified practically always. The goal of the modification is to improve dispersion and/or adhesion in nanotube and spherical particle reinforced composites, and to help exfoliation in nanocomposites containing platelets. However, modification decreases surface energy often leading to decreased interaction with the matrix. Very limited information exists about interphase formation and the properties of the interphase in nanocomposites, although they must influence properties considerably. The properties of nanocomposites are usually far from the expectations, the main reason being insufficient homogeneity, undefined structure and improper adhesion. In spite of considerable difficulties nanocomposites have great potentials especially in functional applications. Several nanocomposite products are already used in industrial practice demonstrated by a few examples in the article.
On the nucleon–nucleon scattering phase shifts through supersymmetry and factorization
Indian Academy of Sciences (India)
U Laha; J Bhoi
2013-12-01
By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase shifts and demonstrate the usefulness of our constructed potentials by means of model calculation.
Nucleon–nucleon scattering in the light of supersymmetric quantum mechanics
Indian Academy of Sciences (India)
J Bhoi; U Laha; K C Panda
2014-05-01
By exploiting supersymmetry-inspired factorization method together with a judiciously chosen deuteron ground-state wave function, approximate higher partial wave nucleon–nucleon potentials are generated. In this context, a minor modification is also introduced to the generated potentials. The n–p scattering phase shifts are computed and analysed via the phase function method.
STRUCTURE AND GRAMMATICAL FUNCTION OF LEO LANGUAGE
Directory of Open Access Journals (Sweden)
I Ketut Yudha
2015-01-01
Full Text Available Lio language is a language spoken in Central Flores. Having limited morphological process in general and affixation process involving verbs (head marking and nouns (dependent marking in particular, it is classified into an isolating language. The studies exploring the languages spoken in the eastern part of Indonesia using Lexical Functional Grammar and the theory of typology are highly limited. In addition, Lio language is merely an isolating one and does not have cross referencing. It is this which inspired the writer to conduct research in syntax. This study aims at investigating the canonic structure, the types of verbs used as predicates, the grammatical function, the alternate of clausal structure, the mapping and the pivotance in Lio language. The results of analysis show that the clauses in Lio language can be divided into basic clauses with verbal and nonverbal predicates. The predicates of the verbal clauses are classified into simple, serial, and causative. The serial verbal constructions are distinguished based on the semantic features of the verbal components forming the serial verbal constructions. These types can be observed from the nature of the relationships among the components forming the serial verbal constructions. A serial verbal construction is made up of more than one verbs and behaves as a simple predicate. There is no dependence marker among the components forming the serial verb. The causative structure also forms monoclause and biclause. The functional mapping uses the features [+/-r] and [+/-o], the argument uses the features [-r] and [-o] which are mapped to SUBJ, [-r] and [+o] are mapped to OBJ, [+r] and [+o] are mapped to OBJ2 or OBJ? and [+r] and [-o] are mapped to OBL (Oblique. Lio language has GF SUBJ and OBJ as the nuclear GF (nuclear grammatical function, and OBL, COMP, and ADJ as the nonnuclear grammatical functions. The SUBJ appears before the verb (preverbal position and the OBJ appears after the verb (postverbal position. Based on how the constituents are ordered, Lio language is an SVO and VOS language. Typologically, it is classified into an ergative as well as accusative language. It is classified into an ergative language as the argument of the unmarked transitive verbal P is similarly treated to the intransitive simple argument depending on how the constituents are ordered. The limitation of Lio language is that P and S can be relativised and modified by the emphatic marker. The only P and S which function as pivots allow the noun which coreferences in both the coordinate and subordinate clauses to disappear.
Nucleon pair approximation description of the low-lying structure of $^{108,109}$Te and $^{109}$I
Jiang, H; Lei, Y; Liotta, R; Wyss, R; Zhao, Y M
2013-01-01
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.
The covariant structure of light-front wave functions and the behavior of hadronic form factors
Brodsky, S J; Hwang, D S; Karmanov, V A
2003-01-01
We study the analytic structure of light-front wave functions (LFWFs) and its consequences for hadron form factors using an explicitly Lorentz-invariant formulation of the front form. The normal to the light front is specified by a general null vector $\\omega^\\mu.$ The LFWFs with definite total angular momentum are eigenstates of a {\\it kinematic} angular momentum operator and satisfy all Lorentz symmetries. They are analytic functions of the invariant mass squared of the constituents $M^2_0= (\\sum k^\\mu)^2$ and the light-cone momentum fractions $x_i= {k_i\\cd \\omega / p \\cd \\omega}$ multiplied by invariants constructed from the spin matrices, polarization vectors, and $\\omega^\\mu.$ These properties are illustrated using known nonperturbative eigensolutions of the Wick--Cutkosky model. We analyze the LFWFs introduced by Chung and Coester to describe static and low momentum properties of the nucleons. They correspond to the spin-locking of a quark with the spin of its parent nucleon, together with a positive-en...
Polarized target for nucleon-nucleon experiments at Saturne II
International Nuclear Information System (INIS)
Continuous improvements of SATURNE polarized target resulted in a flexible and reliable facility for spin physics. For polarized neutron target, two cartridges loaded with 6LiD and 6LiH are set in the refrigerator and can be quickly inserted in the beam. The polarized proton target is a 70 cm3 cartridge loaded with Pentanol-2, a promising material according to the results obtained. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon-nucleon scattering is shown for different targets. copyright 1995 American Institute of Physics
Dilepton production in nucleon-nucleon interactions
International Nuclear Information System (INIS)
Starting from a realistic one-boson-exchange model fitted to the amplitudes of elastic nucleon-nucleon scattering and the process NN?N? we perform a fully relativistic and gauge-invariant calculation for the dilepton production in nucleon-nucleon collisions, including the important effect of propagating the ?-resonance. We compare the results of our calculations with the latest experimental data on dilepton production. We also show how to implement various electromagnetic form factors for the hadrons in our calculations without losing gauge invariance and discuss their influence on dilepton spectra. ((orig.))
Structure-function correlations in tyrosinases.
Kanteev, Margarita; Goldfeder, Mor; Fishman, Ayelet
2015-09-01
Tyrosinases are metalloenzymes belonging to the type-3 copper protein family which contain two copper ions in the active site. They are found in various prokaryotes as well as in plants, fungi, arthropods, and mammals and are responsible for pigmentation, wound healing, radiation protection, and primary immune response. Tyrosinases perform two sequential enzymatic reactions: hydroxylation of monophenols and oxidation of diphenols to form quinones which polymerize spontaneously to melanin. Two other members of this family are catechol oxidases, which are prevalent mainly in plants and perform only the second oxidation step, and hemocyanins, which lack enzymatic activity and are oxygen carriers. In the last decade, several structures of plant and bacterial tyrosinases were determined, some with substrates or inhibitors, highlighting features and residues which are important for copper uptake and catalysis. This review summarizes the updated information on structure-function correlations in tyrosinases along with comparison to other type-3 copper proteins. PMID:26104241
Measurement of the Proton and Deuteron Spin Structure Function g1 in the Resonance Region
International Nuclear Information System (INIS)
We have measured the proton and deuteron spin structure functions g1p and g1d in the region of the nucleon resonances for W2 2 and Q2 ? 0.5 and Q2 ? 1.2 GeV2 by inelastically scattering 9.7 GeV polarized electrons off polarized 15NH3 and 15ND3 targets. We observe significant structure in g1p in the resonance region. We have used the present results, together with the deep-inelastic data at higher W2, to extract ?(Q2) (triplebond) ?01 g1(x,Q2) dx. This is the first information on the low-Q2 evolution of Gamma toward the Gerasimov-Drell-Hearn limit at Q2 = 0
The spin structure function of the neutron
Thomas, A W
2002-01-01
The neutron spin structure function, $g_{1n}$, has been of considerable interest recently in connection with the Bjorken sum rule and the proton spin crisis. Work on this problem has concentrated on measurements at low-$x$. We recall the important, non-perturbative physics to be learnt by going instead to larger values of $x$ and especially from a determination of the place where the expected sign change occurs. Of course, in order to obtain neutron data one must use nuclear targets and apply appropriate corrections. In this regard, we review recent progress concerning the various nuclear corrections that must be applied to measurements on polarised $^3$He.
Exclusive reactions and polarized structure functions
International Nuclear Information System (INIS)
The first properties studied are the counting rules which give the shape of the decreasing process cross-section. The calculation of the pion form factor implies a factorization between a non-perturbative term and a hard amplitude term controlled by a perturbative development. It is shown that these results can be generalized to any hard exclusive process. Other processes which violate the counting rules, such as Landshoff processes are analyzed in order to define a formalism. A quick account of experimental results about colour transparency is made. The last part of the work is dedicated to polarized structure functions and to the new concept of transversal spin. (A.C.)
DIS structure functions in lattice QCD
International Nuclear Information System (INIS)
In this talk I present the complete 1-loop perturbative computation of the renormalization constants and mixing coefficients of quark and gluon lattice operators of rank two and three whose hadronic elements enter in the determination of the first and second moment of deep inelastic scattering structure functions, making use of the nearest-neighbor improved ''clover-leaf'' lattice QCD action. To perform the huge amount of calculations required for the evaluation of all the relevant Feynman diagrams, extensive use of symbolic manipulation languages like Schoonschip and Form has been made. (orig.)
Soft matter nanotechnology from structure to function
Chen, Xiaodong
2015-01-01
Using the well-honed tools of nanotechnology, this book presents breakthrough results in soft matter research, benefitting from the synergies between the chemistry, physics, biology, materials science, and engineering communities. The team of international authors delves beyond mere structure-making and places the emphasis firmly on imparting functionality to soft nanomaterials with a focus on devices and applications. Alongside reviewing the current level of knowledge, they also put forward novel ideas to foster research and development in such expanding fields as nanobiotechnology and nanom
Nucleon-nucleon dynamics at medium energies. Pt. 1
International Nuclear Information System (INIS)
A framework is presented for a unified theory of elastic nucleon-nucleon scattering and single-pion production at medium energies. The model is relativistic, unitary, and takes into account all spin complications. In the simplest version of the theory the driving mechanism is one-pion exchange but the model can be extended to include short-range forces. The resulting set of coupled linear integral equations have the structure of three-body equations and can be solved exactly. The method of solution is discussed. (orig.)
On the nucleon association theory in light nuclei
International Nuclear Information System (INIS)
A new approach to the problem of the association of nucleons in light nuclei is discussed. It is based on the assumption that the same nucleon can simultaneously be a part of several strongly correlated groups of nucleons (clusters). In the framework of this approach a uniform scheme is proposed to construct the ground state wave function of several light nuclei (42+ and H-
Role of the nucleon virtual mass in quark distributions of nuclei
International Nuclear Information System (INIS)
A simple model which allows explicit calculations of the nuclear structure function in terms of the nucleon structure function for the deuteron as well as heavier nuclei is proposed. The impulse approximation in the DIS which leads to the convolution form of the nuclear structure function is examined and forms the basis of the model. The nucleus is viewed as a bound state of nucleons in constant motion with virtual mass less than the mass of a free nucleon. The EMC effect is discussed in the context of the model. Quantitative agreement with the nuclear DIS data is obtained. It was found that most of the nucleus momentum fraction is carried by the nucleons while a small portion is carried by other constituents presumed to be responsible for binding. The momentum fraction of these binding constituents showed saturation behavior similar to that found for the Fermi momentum as the atomic mass number of the nucleus increases, thereby suggesting a relationship between the two. Comparison is made between the model and other possible EMC effect interpretations. Lastly, a decisive test for the convolution form in general and the nuclear virtual mass, in particular, is provided. As predicted by the model, the ratio of nuclear to nucleon Q2- moments are shown to be Q2-independent and the values of this ratio for various nuclei are given
Nucleon-Nucleon Scattering in a Three Dimensional Approach
Fachruddin, I; Glöckle, W; Elster, Ch.
2000-01-01
The nucleon-nucleon (NN) t-matrix is calculated directly as function of two vector momenta for different realistic NN potentials. To facilitate this a formalism is developed for solving the two-nucleon Lippmann-Schwinger equation in momentum space without employing a partial wave decomposition. The total spin is treated in a helicity representation. Two different realistic NN interactions, one defined in momentum space and one in coordinate space, are presented in a form suited for this formulation. The angular and momentum dependence of the full amplitude is studied and displayed. A partial wave decomposition of the full amplitude it carried out to compare the presented results with the well known phase shifts provided by those interactions.
The isospin structure of photoproduction of pi-eta pairs from the nucleon in the threshold region
Käser, A; Annand, J R M; Arends, H J; Bantawa, K; Bartolome, P A; Beck, R; Bekrenev, V; Berghäuser, H; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Costanza, 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; Jahn, O; Jaegle, I; Jude, T C; Kashevarov, V L; Keshelashvili, I; Kondratiev, R; Korolija, M; Kruglov, S P; Krusche, B; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; McGeorge, J C; McNicoll, E; Mekterovic, D; Metag, V; Micanovic, S; Middleton, D G; Mushkarenkov, A; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Otte, P; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S N; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D I; Starostin, A; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P; Werthmüller, D; Witthauer, L
2015-01-01
Photoproduction of $\\pi\\eta$-pairs from nucleons has been investigated from threshold up to incident photon energies of $\\approx$~1.4~GeV. The quasi-free reactions $\\gamma p\\rightarrow p\\pi^0\\eta$, $\\gamma n\\rightarrow n\\pi^0\\eta$, $\\gamma p\\rightarrow n\\pi^+\\eta$, and $\\gamma n\\rightarrow p\\pi^-\\eta$ were for the first time measured from nucleons bound in the deuteron. The corresponding reactions from a free-proton target were also studied to investigate final-state interaction effects (for neutral pions the free-proton results could be compared to previous measurements; the $\\gamma p\\rightarrow n\\pi^+\\eta$ reaction was measured for the first time). For the $\\pi^0\\eta$ final state coherent production via the $\\gamma d\\rightarrow d\\pi^0\\eta$ reaction was also investigated. The experiments were performed at the tagged photon beam of the Mainz MAMI accelerator using an almost $4\\pi$ coverage electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The total cross sections for the four differ...
Tensor-optimized shell model with bare nucleon-nucleon interaction for 4He
Myo, Takayuki; Toki, Hiroshi; Ikeda, Kiyomi
2009-01-01
The pion exchange between nucleons generates a strong tensor interaction, which provides a large attractive contribution for the binding energy of nucleus. This non central tensor interaction is difficult to handle in the shell model framework, which hinders full understanding of nuclear structure. We develop the tensor-optimized shell model (TOSM) for the strong tensor interaction and now we are able to use bare nucleon-nucleon interaction with the help of the unitary corre...
Dynamic versus Static Hadronic Structure Functions
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J.; /SLAC
2009-01-09
'Static' structure functions are the probabilistic distributions computed from the square of the light-front wavefunctions of the target hadron. In contrast, the 'dynamic' structure functions measured in deep inelastic lepton-hadron scattering include the effects of rescattering associated with the Wilson line. Initial- and final-state rescattering, neglected in the parton model, can have a profound effect in QCD hard-scattering reactions, producing single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam-Tung relation in Drell-Yan reactions, nuclear shadowing, and non-universal nuclear antishadowing|novel leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also review how 'direct' higher-twist processes--where a proton is produced in the hard subprocess itself--can explain the anomalous proton-to-pion ratio seen in high centrality heavy ion collisions.
Structural and functional intermetallics - an overview
International Nuclear Information System (INIS)
This overview presents the current status of the research and development of both structural and functional intermetallics. On the one hand, the discussion is focused on commercialization and existing industrial applications of intermetallics. Within this frame the applications of titanium aluminides (TiAl) for turbocharger rotors and exhaust valves in automotive industry are being discussed. Advances in the applications of TiAl alloys for the next generation of turbine blades in aerospace/aircraft segment are also presented. The entire spectrum of nickel and iron aluminide alloys developed commercially by the Oak Ridge national Laboratory (USA) and the examples of their application in various segments of industry are thoroughly discussed. Some inroads made in the application of directionally solidified (DS) multiphase niobium silicides (Nb3Si+Nb5Si3) in situ intermetallic composites with the goal of pushing the service temperature envelope of turbine blades to ? 1200-1300 oC are also discussed. On the other hand, various topics in basic or curiosity driven research of titanium aluminides and trialuminides, iron aluminides and high temperature structural silicides are discussed. Some very recent findings on the improvements in fracture toughness and strength of titanium trialuminides and magnetic behaviour of unconventionally cold - worked iron aluminides are highlighted. The topic of functional intermetallics is limited to the systems must suitable for hydrogen storage applications. A perspective on the directions of future research and development of intermetallics is also provided. (author)
Gelsolin – variety of structure and functions
Directory of Open Access Journals (Sweden)
Adam Sadzy?ski
2010-06-01
Full Text Available Gelsolin is an actin-binding and an actin-fragmenting protein. It contains 730 amino-acids, organized in six G1–G6 homologous domains which determine different functions of the protein. Two variants of gelsolin, cytoplasmic and secreted (contained in plasma are described. Cytoplasmic gelsolin re-organizes the structure of cytoskeleton and plays an important role as a capping protein. In addition, cytoplasmic gelsolin binds bacterial lipopolysaccharide and ATP and exhibits antibacterial and anti-inflammatory properties. Plasma gelsolin is synthesized mainly in skeletal and smooth muscles and myocardium. Plasma gelsolin was also found in: blood, lymph, bronchial epithelia, synovial fluids and cerebro-spinal fluid. The protein plays a role in the immune response, moreover it is involved in extracellular and blood actin-scavenger system. Plasma gelsolin has anti-amyloidogenic, anti-oxidant and anti-apoptotic properties and it has a potential for treatment of Alzheimer disease. Decreased levels of the gelsolin plasma isoform was observed in patients with sepsis, myocardial infarction, liver failure, acute respiratory distress syndrome, inflammations and after burns. On the other hand, after rhabdomyolysis and in amyloidosis gelsolin plasma level are increased. In this review we present recent data on the structure and functions of gelsolin and changes of its activity in some pathological processes.
Functions and structures of eukaryotic recombination proteins
International Nuclear Information System (INIS)
We have found that Rad51 and RecA Proteins form strikingly similar structures together with dsDNA and ATP. Their right handed helical nucleoprotein filaments extend the B-form DNA double helixes to 1.5 times in length and wind the helix. The similarity and uniqueness of their structures must reflect functional homologies between these proteins. Therefore, it is highly probable that similar recombination proteins are present in various organisms of different evolutional states. We have succeeded to clone RAD51 genes from human, mouse, chicken and fission yeast genes, and found that the homologues are widely distributed in eukaryotes. The HsRad51 and MmRad51 or ChRad51 proteins consist of 339 amino acids differing only by 4 or 12 amino acids, respectively, and highly homologous to both yeast proteins, but less so to Dmcl. All of these proteins are homologous to the region from residues 33 to 240 of RecA which was named ''homologous core. The homologous core is likely to be responsible for functions common for all of them, such as the formation of helical nucleoprotein filament that is considered to be involved in homologous pairing in the recombination reaction. The mouse gene is transcribed at a high level in thymus, spleen, testis, and ovary, at lower level in brain and at a further lower level in some other tissues. It is transcribed efficiently in recombination active tissues. A clear functional difference of Rad51 homologues from RecA was suggested by the failure of heterologous genes to complement the deficiency of Scrad51 mutants. This failure seems to reflect the absence of a compatible partner, such as ScRad52 protein in the case of ScRad51 protein, between different species. Thus, these discoveries play a role of the starting point to understand the fundamental gene targeting in mammalian cells and in gene therapy. (J.P.N.)
Structure and Function of KH Domains
Energy Technology Data Exchange (ETDEWEB)
Valverde, R.; Regan, E
2008-01-01
The hnRNP K homology (KH) domain was first identified in the protein human heterogeneous nuclear ribonucleoprotein K (hnRNP K) 14 years ago. Since then, KH domains have been identified as nucleic acid recognition motifs in proteins that perform a wide range of cellular functions. KH domains bind RNA or ssDNA, and are found in proteins associated with transcriptional and translational regulation, along with other cellular processes. Several diseases, e.g. fragile X mental retardation syndrome and paraneoplastic disease, are associated with the loss of function of a particular KH domain. Here we discuss the progress made towards understanding both general and specific features of the molecular recognition of nucleic acids by KH domains. The typical binding surface of KH domains is a cleft that is versatile but that can typically accommodate only four unpaired bases. Van der Waals forces and hydrophobic interactions and, to a lesser extent, electrostatic interactions, contribute to the nucleic acid binding affinity. 'Augmented' KH domains or multiple copies of KH domains within a protein are two strategies that are used to achieve greater affinity and specificity of nucleic acid binding. Isolated KH domains have been seen to crystallize as monomers, dimers and tetramers, but no published data support the formation of noncovalent higher-order oligomers by KH domains in solution. Much attention has been given in the literature to a conserved hydrophobic residue (typically Ile or Leu) that is present in most KH domains. The interest derives from the observation that an individual with this Ile mutated to Asn, in the KH2 domain of fragile X mental retardation protein, exhibits a particularly severe form of the syndrome. The structural effects of this mutation in the fragile X mental retardation protein KH2 domain have recently been reported. We discuss the use of analogous point mutations at this position in other KH domains to dissect both structure and function.
Annexin A2 Heterotetramer: Structure and Function
Directory of Open Access Journals (Sweden)
David Waisman
2013-03-01
Full Text Available Annexin A2 is a pleiotropic calcium- and anionic phospholipid-binding protein that exists as a monomer and as a heterotetrameric complex with the plasminogen receptor protein, S100A10. Annexin A2 has been proposed to play a key role in many processes including exocytosis, endocytosis, membrane organization, ion channel conductance, and also to link F-actin cytoskeleton to the plasma membrane. Despite an impressive list of potential binding partners and regulatory activities, it was somewhat unexpected that the annexin A2-null mouse should show a relatively benign phenotype. Studies with the annexin A2-null mouse have suggested important functions for annexin A2 and the heterotetramer in fibrinolysis, in the regulation of the LDL receptor and in cellular redox regulation. However, the demonstration that depletion of annexin A2 causes the depletion of several other proteins including S100A10, fascin and affects the expression of at least sixty-one genes has confounded the reports of its function. In this review we will discuss the annexin A2 structure and function and its proposed physiological and pathological roles.
Phototriggered functionalization of hierarchically structured polymer brushes.
de los Santos Pereira, Andres; Kostina, Nina Yu; Bruns, Michael; Rodriguez-Emmenegger, Cesar; Barner-Kowollik, Christopher
2015-06-01
The precise design of bioactive surfaces, essential for the advancement of many biomedical applications, depends on achieving control of the surface architecture as well as on the ability to attach bioreceptors to antifouling surfaces. Herein, we report a facile avenue toward hierarchically structured antifouling polymer brushes of oligo(ethylene glycol) methacrylates via surface-initiated atom transfer radical polymerization (SI-ATRP) presenting photoactive tetrazole moieties, which permitted their functionalization via nitrile imine-mediated tetrazole-ene cyclocloaddition (NITEC). A maleimide-functional ATRP initiator was photoclicked to the side chains of a brush enabling a subsequent polymerization of carboxybetaine acrylamide to generate a micropatterned graft-on-graft polymer architecture as evidenced by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Furthermore, the spatially resolved biofunctionalization of the tetrazole-presenting brushes was accessed by the photoligation of biotin-maleimide and subsequent binding of streptavidin. The functionalized brushes bearing streptavidin were able to resist the fouling from blood plasma (90% reduction with respect to bare gold). Moreover, they were employed to demonstrate a model biosensor by immobilization of a biotinylated antibody and subsequent capture of an antigen as monitored in real time by surface plasmon resonance. PMID:25961109
Structure, dynamics, and function of biomolecules
International Nuclear Information System (INIS)
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors enhanced Los Alamos' core competency in Bioscience and Biotechnology by building on present strengths in experimental techniques, theory, high-performance computing, modeling, and simulation applied to biomolecular structure, dynamics, and function. Specifically, the authors strengthened their capabilities in neutron/x-ray scattering, x-ray crystallography, NMR, laser, and optical spectroscopies. Initially they focused on supporting the Los alamos Neutron Science Center (LANSCE) in the design and implementation of new neutron scattering instrumentation, they developed new methods for analysis of scattering data, and they developed new projects to study the structures of biomolecular complexes. The authors have also worked to strengthen interactions between theory and experiment, and between the biological and physical sciences. They sponsored regular meetings of members from all interested LANL technical divisions, and supported two lecture series: ''Biology for Physicists'' and ''Issues in Modern Biology''. They also supported the formation of interdisciplinary/inter-divisional teams to develop projects in science-based bioremediation and an integrated structural biology resource. Finally, they successfully worked with a multidisciplinary team to put forward the Laboratory's Genome and Beyond tactical goal
Sauer, Peter U
2014-01-01
The role of three-nucleon forces in ab initio calculations of nuclear systems is investigated. The difference between genuine and induced many-nucleon forces is emphasized. Induced forces arise in the process of solving the nuclear many-body problem as technical intermediaries towards calculationally converged results. Genuine forces make up the Hamiltonian; they represent the chosen underlying dynamics. The hierarchy of contributions arising from two-, three- and many-nucleon forces is discussed. Signals for the need of the inclusion of genuine three-nucleon forces are studied in nuclear systems, technically best under control, especially in three-nucleon and four-nucleon systems. Genuine three-nucleon forces are important for details in the decription of some observables. Their contributions to observables are small on the scale set by two-nucleon forces.
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
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.
Network motifs: structure does not determine function
Directory of Open Access Journals (Sweden)
Stumpf Michael PH
2006-05-01
Full Text Available Abstract Background A number of publications have recently examined the occurrence and properties of the feed-forward motif in a variety of networks, including those that are of interest in genome biology, such as gene networks. The present work looks in some detail at the dynamics of the bi-fan motif, using systems of ordinary differential equations to model the populations of transcription factors, mRNA and protein, with the aim of extending our understanding of what appear to be important building blocks of gene network structure. Results We develop an ordinary differential equation model of the bi-fan motif and analyse variants of the motif corresponding to its behaviour under various conditions. In particular, we examine the effects of different steady and pulsed inputs to five variants of the bifan motif, based on evidence in the literature of bifan motifs found in Saccharomyces cerevisiae (commonly known as baker's yeast. Using this model, we characterize the dynamical behaviour of the bi-fan motif for a wide range of biologically plausible parameters and configurations. We find that there is no characteristic behaviour for the motif, and with the correct choice of parameters and of internal structure, very different, indeed even opposite behaviours may be obtained. Conclusion Even with this relatively simple model, the bi-fan motif can exhibit a wide range of dynamical responses. This suggests that it is difficult to gain significant insights into biological function simply by considering the connection architecture of a gene network, or its decomposition into simple structural motifs. It is necessary to supplement such structural information by kinetic parameters, or dynamic time series experimental data, both of which are currently difficult to obtain.
Universality of nucleon-nucleon short-range correlations and nucleon momentum distributions
Alvioli, Massimiliano; Kaptari, Leonid P; Mezzetti, Chiara Benedetta; Morita, Hiko
2013-01-01
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 ($k_{rel}$) and center-of-mass (c.m.) ($K_{c.m.}$) momenta, as well as upon the angle $\\Theta$ between them, exhibits a remarkable property: in the region $k_{rel}\\gtrsim 2\\,fm^{-1}$ and $K_{c.m.}\\lesssim 1\\,fm^{-1} $, the relative and c.m. motions are decoupled and the two-nucleon momentum distribution fa...
Nucleon properties from unconventional interpolating fields
International Nuclear Information System (INIS)
Interpolating fields, used to excite hadrons from the QCD vacuum in nonperturbative field-theoretic investigations of hadron properties, are explored with an emphasis on unconventional nucleon interpolators. The QCD continuum model for excited state contributions to QCD correlation functions is a central element in extracting the physics contained in these alternate correlation functions. The analysis confirms the independence of nucleon properties obtained from different interpolating fields. However, this independence comes about in a trivial manner. These results provide a resolution to the long standing debate over the optimal nucleon interpolating field to be used in QCD sum rule analyses
Energy Technology Data Exchange (ETDEWEB)
EN YO,H.; SAITO,N.; SHIBATA,T.A.; YAZAKI,K.; BUNCE,G.
2002-03-29
The RIKEN School on ''Quark-Gluon Structure of the Nucleon and QCD'' was held from March 29th through 31st at the Nishina Memorial Hall of RIKEN, Wako, Saitama, Japan, sponsored by RIKEN (the Institute of Physical and Chemical Research). The school was the second of a new series with a broad perspective of hadron and nuclear physics. The purpose of the school was to offer young researchers an opportunity to learn theoretical aspects of hadron physics based on QCD and related experimental programs being or to be carried out by Japanese groups. We had 3 theoretical courses, each consisting of 3 one-hour lectures, and 6 experimental courses, each consisting of a one-hour lecture.
Controlling Function and Structure with DNA
DEFF Research Database (Denmark)
TØrring, Thomas
2011-01-01
In this thesis, the research on three different topics will be described. The overall area of the research is DNA nanotechnology, and the first chapter is therefore an introduction to DNA, and its advantages as a building material. The first research topic is the development of a new method for constructing DNA-protein hybrids. The project is still ongoing, but our initial results and thoughts on the design are reported. The design was based on the concept of DNA directed chemistry, where stable covalent bonds are directed by weaker non-covalent bonds. Applying this concept, an aptamer for the human ?-thrombin was used to direct an oligonucleotide with an activated ester capable of forming covalent bonds with the lysine amino acids. Initial results have demonstrated that such rationally designed systems could indeed result in DNA-protein conjugates. Furthermore, future research strategies and ideas are presented. The second research topic concerns our contributions to the field of DNA origami. This includesinvestigations of single molecule reactions on a DNA origami platform. The reaction between an amine and an activated ester, as well as the Huisgen-Meldal-Sharpless reaction were investigated on a two dimensional DNA origami platform. This was done by incorporating functional groups on the surface of the origami, and reacting these with biotin analogues carrying the complementary functional groups. Successful reactions could then be observed using atomic force microscopy after addition of the protein streptavidin. While the implementation of chemical functionalities on origami can be achieved during automated DNA synthesis, this is laborious and costly. In a separate research project we aimed at improving the accessibility by applying an enzymatic labelling method. We demonstrated that the DNA origami could be massively modified fast and efficiently with versatile groups such as amines, fluorophores and biotin. Applying small dynamic DNA structures to control the function of so-called photosensitizers, was the aim of the third and final research topic presented. Photosensitizers are functional molecules that upon irradiation can excite naturally occurring triplet oxygen to the cytotoxic singlet oxygen. This process is interesting in terms of photodynamic therapy, but lack of control is limiting the applications. The excitation can be controlled by installing quenching molecules close to the photosensitizer, and we exploited this by tethering the two molecules together with a dynamic DNA nanostructure, known as an i-motif. This allowed us to control the distance between the two molecules, and thereby the excitation of triplet oxygen. Finally, the thesis is concluded with an outlook and possible future research strategies.
Energy Technology Data Exchange (ETDEWEB)
Kim, Sung-Hou; Shin, Dong Hae; Hou, Jingtong; Chandonia, John-Marc; Das, Debanu; Choi, In-Geol; Kim, Rosalind; Kim, Sung-Hou
2007-09-02
Advances in sequence genomics have resulted in an accumulation of a huge number of protein sequences derived from genome sequences. However, the functions of a large portion of them cannot be inferred based on the current methods of sequence homology detection to proteins of known functions. Three-dimensional structure can have an important impact in providing inference of molecular function (physical and chemical function) of a protein of unknown function. Structural genomics centers worldwide have been determining many 3-D structures of the proteins of unknown functions, and possible molecular functions of them have been inferred based on their structures. Combined with bioinformatics and enzymatic assay tools, the successful acceleration of the process of protein structure determination through high throughput pipelines enables the rapid functional annotation of a large fraction of hypothetical proteins. We present a brief summary of the process we used at the Berkeley Structural Genomics Center to infer molecular functions of proteins of unknown function.
Structure, Function, and Evolution of Rice Centromeres
Energy Technology Data Exchange (ETDEWEB)
Jiang, Jiming
2010-02-04
The centromere is the most characteristic landmark of eukaryotic chromosomes. Centromeres function as the site for kinetochore assembly and spindle attachment, allowing for the faithful pairing and segregation of sister chromatids during cell division. Characterization of centromeric DNA is not only essential to understand the structure and organization of plant genomes, but it is also a critical step in the development of plant artificial chromosomes. The centromeres of most model eukaryotic species, consist predominantly of long arrays of satellite DNA. Determining the precise DNA boundary of a centromere has proven to be a difficult task in multicellular eukaryotes. We have successfully cloned and sequenced the centromere of rice chromosome 8 (Cen8), representing the first fully sequenced centromere from any multicellular eukaryotes. The functional core of Cen8 spans ~800 kb of DNA, which was determined by chromatin immunoprecipitation (ChIP) using an antibody against the rice centromere-specific H3 histone. We discovered 16 actively transcribed genes distributed throughout the Cen8 region. In addition to Cen8, we have characterized eight additional rice centromeres using the next generation sequencing technology. We discovered four subfamilies of the CRR retrotransposon that is highly enriched in rice centromeres. CRR elements are constitutively transcribed and different CRR subfamilies are differentially processed by RNAi. These results suggest that different CRR subfamilies may play different roles in the RNAi-mediated pathway for formation and maintenance of centromeric chromatin.
Structure and biological functions of fungal cerebrosides
Directory of Open Access Journals (Sweden)
Barreto-Bergter Eliana
2004-01-01
Full Text Available Ceramide monohexosides (CMHs, cerebrosides are glycosphingolipids composed of a hydrophobic ceramide linked to one sugar unit. In fungal cells, CMHs are very conserved molecules consisting of a ceramide moiety containing 9-methyl-4,8-sphingadienine in amidic linkage to 2-hydroxyoctadecanoic or 2-hydroxyhexadecanoic acids, and a carbohydrate portion consisting of one residue of glucose or galactose. 9-Methyl 4,8-sphingadienine-containing ceramides are usually glycosylated to form fungal cerebrosides, but the recent description of a ceramide dihexoside (CDH presenting phytosphingosine in Magnaporthe grisea suggests the existence of alternative pathways of ceramide glycosylation in fungal cells. Along with their unique structural characteristics, fungal CMHs have a peculiar subcellular distribution and striking biological properties. In Pseudallescheria boydii, Candida albicans, Cryptococcus neoformans, Aspergillus nidulans, A. fumigatus, and Schizophyllum commune, CMHs are apparently involved in morphological transitions and fungal growth. The elucidation of structural and functional aspects of fungal cerebrosides may therefore contribute to the design of new antifungal agents inhibiting growth and differentiation of pathogenic species.
Structural and functional diversity of viral IRESes.
Balvay, Laurent; Soto Rifo, Ricardo; Ricci, Emiliano P; Decimo, Didier; Ohlmann, Théophile
2009-01-01
Some 20 years ago, the study of picornaviral RNA translation led to the characterization of an alternative mechanism of initiation by direct ribosome binding to the 5' UTR. By using a bicistronic vector, it was shown that the 5' UTR of the poliovirus (PV) or the Encephalomyelitis virus (EMCV) had the ability to bind the 43S preinitiation complex in a 5' and cap-independent manner. This is rendered possible by an RNA domain called IRES for Internal Ribosome Entry Site which enables efficient translation of an mRNA lacking a 5' cap structure. IRES elements have now been found in many different viral families where they often confer a selective advantage to allow ribosome recruitment under conditions where cap-dependent protein synthesis is severely repressed. In this review, we compare and contrast the structure and function of IRESes that are found within 4 distinct family of RNA positive stranded viruses which are the (i) Picornaviruses; (ii) Flaviviruses; (iii) Dicistroviruses; and (iv) Lentiviruses. PMID:19632368
PREFACE: Structure and Function of Biomolecules
Cieplak, Marek; Sienkiewicz, Andrzej
2005-05-01
The Workshop on the Structure and Function of Biomolecules took place in Bedlewo near Poznan, Poland, on 13-15 May 2004, two weeks after Poland joined the European Community. The Workshop was sponsored by the ASPECT Centre of Excellence for Advanced Spectroscopy Applications in Physics, Modern Science, Biology and Environmental Protection (the European Community contract GMA1-2002-72801) and by the Institute of Physics, Polish Academy of Sciences. The Workshop gathered together approximately 100 participants mostly from the European Community but also from Canada, Russia, Switzerland, Turkey and the USA. The scientific aim of this Workshop was to provide an active forum for cross-disciplinary interactions between specialists who are active in different fields related to biomolecules, with an emphasis on proteins and nucleic acids. The workshop covered both experimental and theoretical issues. The subjects that were discussed included: mechanical stretching of biomolecules, protein kinetics and structure, aggregation of biomolecules, and novel spectroscopic methods for studying protein conformation. There were 36 invited lectures and 33 poster contributions presented at the Workshop. This Special Issue of Journal of Physics: Condensed Matter contains a sample of the research presented at the Workshop.
Neutral-current x-distributions in the neutrino-nucleon scattering
International Nuclear Information System (INIS)
In this thesis the measurement of the x distribution of the structure functions for deep inelastic charged-current and neutral-current neutrino-nucleon interactions at the CERN 200 GeV narrow-band neutrino beam is described. (HSI)
What do we learn from polarization measurements in deep-inelastic electron-nucleon scattering
International Nuclear Information System (INIS)
We examine what can be learned from deep-inelastic electron-nucleon scattering with polarized initial electrons and measurement of the polarization of the final electrons. A direct evaluation of the separate structure functions W1 and W2 is shown to be possible
Nucleon and flavor form factors in a light front quark model in AdS/QCD
Chakrabarti, Dipankar; Mondal, Chandan(Department of Physics, Indian Institute of Technology Kanpur, 208016, Kanpur , India)
2013-01-01
Using the light front wave functions for the nucleons in a quark model in AdS/QCD, we calculate the nucleon electromagnetic form factors. The flavor decompositions of the nucleon form factors are calculated from the GPDs in this model. We show that the nucleon form factors and their flavor decompositions calculated in AdS/QCD are in agreement with experimental data.
Kataev, A. L.; A.V. Kotikov; Parente, G.; Sidorov, A. V.
1997-01-01
The next-to-next-to-leading order (NNLO) QCD analysis of the revised experimental data of the CCFR collaboration for the $xF_3$ structure function of the deep-inelastic scattering of neutrinos and antinuetrinos on the nucleons is made by means of the Jacobi polynomial expansion technique. The NNLO values of the QCD coupling constant are determined both without and with twist--4 contributions taken into account. Theoretical ambiguities of $\\alpha_s$ are fixed using the method...
Measurements of the Proton and Deuteron Spin Structure Function g2 and Asymmetry A2
Energy Technology Data Exchange (ETDEWEB)
K. Abe; T. Akagi; P. L. Anthony; R. Antonov; R. G. Arnold; T. Averett; H. R Band; J. M. Bauer; H. Borel; P.E. Bosted; V. Breton; J. Button-Shafer; J.P. Chen; T.E. Chupp; J. Clendenin; C. Comptour; K. P. Coulter; G. Court; D. Crabb; M. Daoudi; D. Day; F. S. Dietrich; J. Dunne; H. Dutz; R. Erbacher; J. Fellbaum; A. Feltham; H. Fonvieille; E. Frlez; D. Garvey; R. Gearhart; J. Gomez; P. Grenier; K. A. Griffioen; S. Hoibraten; E. W. Hughes; C. Hyde-Wright; J. R. Johnson; D. Kawall; A. Klein; S. E. Kuhn; M. Kuriki; R. Lindgren; T. J. Liu; R. M. Lombard-Nelsen; J. Marroncle; T. Marnyama; X. K. Marnyama; J. McCarthy; W. Meyer; Z.-E. Meziani; R. Minehart; J. Mitchell; J. Morgenstern; G. G. Petratos; R. Pitthan; D. Pocanic; C. Prescott; R. Prepost; P. Raines; B. Raue; D. Reyna; A. Rijllart; Y. Roblin; L. S. Rochester; S. E. Rock; O. A. Rondon; I. Sick; L. C. Smith; T. B. Smith; M. Spengos; F. Staley; P. Steiner; S. St.Lorant; L. M. Stuart; F. Suekane; Z. M. Szalata; H. Tang; Y. Terrien; T. Usher; D. Walz; J.L. White; K. Witte; C.C. Young; B. Youngman; H. Yuta; G. Zapalac; B. Zihlmann; D. Zimmermann
1996-01-22
We have measured proton and deuteron virtual photon-nucleon asymmetries A{sup p}{sub 2} and A{sup d}{sub 2} and structure functions g{sup p}{sub 2} and g{sup d}{sub 2} over the range 0.03 < x < 0.8 and 1.3 < Q{sup 2} < 10 (GeV/c){sup 2} by inelastically scattering polarized electrons off polarized ammonia targets. Results for A{sub 2} are significantly smaller than the positivity limit (sqrt)R for both targets. Within experimental precision the g{sub 2} data are well described by the twist-2 contribution, g{sup ww}{sub 2}. Twist-3 matrix elements have been extracted and are compared to theoretical predictions.
Measurements of the longitudinal structure function and |$V_{cs}$| in the CCFR experiment
Yang, U K; Arroyo, C G; Bazarko, A O; Bernstein, R H; Bodek, Arie; Bolton, T; Budd, H S; Conrad, J; Harris, D A; Johnson, R A; Kim, J H; King, B J; Kinnel, T; Lamm, M J; Lefmann, W C; Marsh, W; McFarland, K S; Mishra, S R; Naples, D; Quintas, P Z; 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
1998-01-01
Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F_2, xF_3(nu), xF_3(nubar) and R(longitudinal) in the kinematic region 0.01
Quark-hadron duality in spin structure functions g1p and g1d
International Nuclear Information System (INIS)
New measurements of the spin structure functions of the proton and deuteron g1p(x,Q2) and g1d(x,Q2) in the nucleon resonance region are compared with extrapolations of target-mass-corrected next-to-leading-order (NLO) QCD fits to higher energy data. Averaged over the entire resonance region (W2 dependence for Q2>1.7 GeV2/c2. This ''global'' duality appears to result from cancellations among the prominent ''local'' resonance regions: in particular strong ?3/2 contributions in the ?(1232) region appear to be compensated by strong ?1/2 contributions in the resonance region centered on 1.5 GeV. These results are encouraging for the extension of NLO QCD fits to lower W and Q2 than have been used previously
Leading and higher twists in proton, neutron and deuteron unpolarized structure functions F2
Energy Technology Data Exchange (ETDEWEB)
S. Simula
2007-03-01
We summarize the results of a recent global analysis of proton and deuteron F2 structure function world data performed over a large range of kinematics, including recent measurements done at JLab with the CLAS detector. From these data the lowest moments (n?10) of the unpolarized structure functions are determined with good statistics and systematics. The Q2 evolution of the extracted moments is analyzed in terms of an OPE-based twist expansion, taking into account soft-gluon effects at large x. A clean separation among the leading- and higher-twist terms is achieved. By combining proton and deuteron measurements the lowest moments of the neutron F2 structure function are determined and its leading-twist term is extracted. Particular attention is paid to nuclear effects in the deuteron, which become increasingly important for the higher moments. Our results for the non-singlet, isovector (p-n) combination of the leading-twist moments are used to test recent lattice simulations. We also determine the lowest few moments of the higher-twist contributions, and find these to be approximately isospin independent, suggesting the possible dominance of ud correlations over uu and dd in the nucleon.
International Nuclear Information System (INIS)
The asymptotic normalization constants (ANC) C0 and C2 of the triton have been calculated by the hyperspherical harmonics expansion method with the Reid soft core potential (no three body force). The results do not agree with the corresponding calculations by the Faddeev method, when only a few hyperspherical partial waves are included. However Schneider's convergence theorems on hyperspherical expansion allow one to extrapolate the results for a large number of partial waves and then they agree fairly well with the Faddeev results. This indicates that even though the hyperspherical expansion for the asymptotic wave function is very slow, a convergent and reliable wave function is attained by extrapolation of a relatively small-sized calculation
Carbone, Arianna; Rios, Arnau; Polls, Artur
2013-01-01
We present calculations for symmetric nuclear matter using chiral nuclear interactions within the Self-Consistent Green's Functions approach in the ladder approximation. Three-body forces are included via effective one-body and two-body interactions, computed from an uncorrelated average over a third particle. We discuss the effect of the three-body forces on the total energy, computed with an extended Galitskii-Migdal-Koltun sum-rule, as well as on single-particle propertie...
Energy Technology Data Exchange (ETDEWEB)
Pita, S
2000-09-01
The structure of the neutron rich light nuclei {sup 11}Be and {sup 10}Li has been investigated by means of one nucleon transfer reactions. The experiments have been carried out at GANIL in inverse kinematics using {sup 11}Be secondary beams. The {sup 11}Be(p,d){sup 10}Be reaction bas been studied at 35.3 MeV/u. The {sup 10}Be ejectiles were analyzed by the spectrometer SPEG, and coincident deuterons were detected in the position sensitive silicon detector CHARISSA. Transfer cross sections to 0{sup +}{sub 1} and 2{sup +}{sub 1}, states in {sup 10}Be were measured up to {theta}{sub CM} = 16 deg. and compared to DWBA and CRC predictions. The effects of neutron-cure couplings on reaction form factors have been studied by solving coupled equations in the framework of a vibrational model. It is shown that the rate of core excitation {sup 10}Be{sub 2+} in the {sup 11}Be{sub gs} wave function is overestimated by a standard analysis with form factors given by the usual Separation Energy prescription. The former model predicts a rate of core excitation of 16% and leads to theoretical cross sections which are in good agreement with the experimental data. The aim of the {sup 11}Be(d,{sup 3}He){sup 10}Li experiment, realized at 37 MeV/u, was to measure the distribution of the 2s neutron strength in the unbound nucleus {sup 10}Li. The energy spectrum was deduced from the {sup 3}He energy and angle measured by the silicon strip detector array MUST. An asymmetric peak is clearly observed near the threshold, with a maximum at -S{sub n} = 130 keV. This constitutes a direct proof of the inversion of 2s and 1p{sub 1/2} shells in {sup 10}Li, which was until now a controversial question in spite of many experimental efforts. On the other band the analysis of the {sup 11}Be(d,t){sup 10}Be reaction studied in the same experiment confirms the results obtained in the {sup 11}Be(p,d){sup 10}Be reaction concerning the {sup 11}Be{sub gs} structure. This work shows the interest and feasibility of studies of the shell properties of exotic nuclei using transfer reactions induced by radioactive beams and constitutes the beginning of a program devoted to this kind of experiment. (author)
Third-order QCD corrections to the charged-current structure function F_3
Moch, S; Vogt, A
2008-01-01
We compute the coefficient function for the charge-averaged W^(+/-)-exchange structure function F_3 in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling alpha_s and of 1/Q^2 power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F_3 in powers of alpha_s is stable at all values of x relevant to measurements at high scales Q^2. At small x the third-order coefficient function is dominated by diagrams with the colour structure d_abc d^abc not present at lower orders. At large x the coefficient function for F_3 is identical to that of F_1 up to terms vanishing for x to 1.
Carbone, Arianna; Polls, Artur
2013-01-01
We present calculations for symmetric nuclear matter using chiral nuclear interactions within the Self-Consistent Green's Functions approach in the ladder approximation. Three-body forces are included via effective one-body and two-body interactions, computed from an uncorrelated average over a third particle. We discuss the effect of the three-body forces on the total energy, computed with an extended Galitskii-Migdal-Koltun sum-rule, as well as on single-particle properties. Saturation properties are substantially improved when three-body forces are included, but there is still some underlying dependence on the renormalization scale.
Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order
Epelbaum, E; Meißner, U -G
2014-01-01
We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362], [D.R. Entem, R. Machleidt, Phys. Rev. C68 (2003) 041001] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c_i and d_i determined from pion-nucleon scattering without any fine tuning. We discuss in detail t...
Rychlewski Leszek; Ginalski Krzysztof; Plewczynski Dariusz; von Grotthuss Marcin; Shakhnovich Eugene I
2006-01-01
Abstract Background The number of protein structures from structural genomics centers dramatically increases in the Protein Data Bank (PDB). Many of these structures are functionally unannotated because they have no sequence similarity to proteins of known function. However, it is possible to successfully infer function using only structural similarity. Results Here we present the PDB-UF database, a web-accessible collection of predictions of enzymatic properties using structure-function rela...
Pionic background for nucleon-nucleon observables
International Nuclear Information System (INIS)
We present a method that allows the unambiguous definition of the one-pion exchange contribution to nucleon-nucleon scattering observables, and then use it to determine those waves where values of phase shifts and mixing parameters may be understood as sums of pionic and non-pionic dynamical effects. This helps the assessment of the explicative power of the various existing phenomenological potentials and may eventually lead to ways of discriminating their effectiveness. (author)
Pionic background for nucleon-nucleon observables
International Nuclear Information System (INIS)
A method is presented that allows the unambiguous definition of the one pion exchange contribution to nucleon-nucleon scattering observables and then use it to determine those waves where values of phase shifts and mixing parameters may be understood as sums of pionic and non-pionic dynamical effects. This helps the assessment of the explicative power of the various existing phenomenological potentials and may eventually lead to ways of discriminating their effectiveness. (author) 16 refs.; 19 figs.; 2 tabs
Structure and function of DNA polymerase ?
International Nuclear Information System (INIS)
DNA polymerases are enzymes playing the central role in DNA metabolism, including DNA replication, DNA repair and recombination. DNA polymerase ? (pol ? DNA polymerase ? (pol ?) and terminal deoxynucleotidyltransferase (TdT) in X family DNA polymerases function in non-homologous end-joining (NHEJ), which is the predonmiant repair pathway for DNA double-strand breaks (DSBs). NHEJ involves enzymes that capture both ends of the broken DNA strand, bring them together in a synaptic DNA-protein complex, and repair the DSB. Pol ? and pol ? fill in the gaps at the junction to maintain the genomic integrity. TdT synthesizes N region at the junction during V(D)J recombination and promotes diversity of immunoglobulin or T-cell receptor gene. Among these three polymerases, the regulatory mechanisms of pol ? remain rather unclear. We have approached the mechanism of pol ? from both sides of structure and cellular dynamics. Here, we propose some new insights into pol ? and the probable NHEJ model including our findings. (author)
Universality in low energy states: from few-atoms to few-nucleons
Kievsky, A
2013-01-01
We investigate universal behavior in elastic atom-dimer scattering below the dimer breakup threshold calculating the atom-dimer effective-range function $ak\\cot\\delta$. We compare our results with the universal zero-range form deduced by Efimov, $ak\\cot\\delta=c_1(ka)+c_2(ka)\\cot[s_0\\ln(a\\kappa_*)+\\phi(ka)]$, for different values of the two-body scattering length $a$ and of the three-body parameter $\\kappa_*$. We observe a good agreement introducing a particular type of finite-range corrections. Furthermore, we show that the same parameterization describes a very different system: nucleon-deuteron scattering below the deuteron breakup threshold. Our analysis reveals a universal behavior that ranges from few-atom systems to few-nucleon systems, and clarifies the nature of the pole structure in the effective-range function of nucleon-deuteron scattering.
Structure and function of small arteries
DEFF Research Database (Denmark)
Mulvany, M J; Aalkjær, Christian
1990-01-01
The small arteries (prearteriolar vessels with lumen diameter less than approximately 500 microns) contribute importantly to and participate actively in the regulation of the peripheral resistance. New techniques, building on the classic histological and hemodynamic techniques, have enabled detailed in vitro investigation of small arteries. At present, research in small arteries is in its infancy, and our understanding of the heterogeneity of small arteries within vascular beds, between vascular beds, and between species is extremely limited. This review attempts to describe the current status of the field. New techniques, based primarily on a wire myograph (where the vessels are mounted as ring preparations) and a pressure myograph (where vessels are cannulated and pressure-lumen relations are determined), have allowed in vitro investigations of small arteries. The more physiological arrangement of the pressure myograph allows, for example, investigation of the vasoconstrictor response to raised intravascular pressure (the Bayliss response), whereas the less-sophisticated wire myograph is similar to use and may be more useful in certain situations where particular mechanisms are being investigated. Both techniques allow simultaneous measurements of vessel tone and a variety of parameters (e.g., membrane potential and intracellular ion activities) and thus allow precise determination of the relation between small artery structure and function. The vessels appear to remain fully viable with regard to the contractility of their smooth muscle cells as well as to the function of their perivascular nerves and their endothelium. The evidence suggests that the monovalent transport mechanisms in the plasma membrane, in particular potassium channels, play an important role in the determination of the membrane potential in small arteries, although the relation is more complex than indicated by the Goldman equation. Confirmation of these findings requires, however, simultaneous determinations of ion transport and vascular tone under conditions where vessels are subjected to mechanical loading. The membrane potential, through its effect on potential-dependent calcium channels, plays an important role in the determination of vascular tone. With regard to calcium homeostasis, current knowledge is hampered by the lack of direct measurements of the relation between cytoplasmic calcium and vascular tone. The evidence, however, suggests that besides potential-dependent calcium channels, receptor-operated calcium channels are present in the plasma membrane, although this still requires confirmation. The role of the sarcoplasmic reticulum is not clarified.(ABSTRACT TRUNCATED AT 400 WORDS)
Exclusive experiments on few nucleon systems at Saclay
International Nuclear Information System (INIS)
The transverse and longitudinal responses for the 4He(e,e'p)3H reaction have been separated in the low missing momentum region. The transverse spectral function agrees with theory whereas the longitudinal spectral function is low by 30%. The 4He(e,e'p)X reaction was studied at high missing momenta. The continuum cross-section (X = 2H,n and X = pnn) dominates over the two-body break-up (X = 3H) for pm > 300 MeV/c. Moreover, this continuum cross-section has a characteristic structure that reveals an effect of short-range correlation between two nucleons
Nuclear enhanced power corrections to DIS structure functions
Guo, Xiaofeng; Qiu, Jianwei; Zhu, Wei
2001-01-01
We calculate nuclear enhanced power corrections to structure functions measured in deeply inelastic lepton-nucleus scattering in Quantum Chromodynamics (QCD). We find that the nuclear medium enhanced power corrections at order of $O(\\alpha_s/Q^2)$ enhance the longitudinal structure function $F_L$, and suppress the transverse structure function $F_1$. We demonstrate that strong nuclear effects in $\\sigma_A/\\sigma_D$ and $R_A/R_D$, recently observed by HERMES Collaboration, ca...
Nucleon Form Factors in Dispersion Theory
Hammer, H.-W.
2006-01-01
Dispersion relations provide a powerful tool to analyse the electromagnetic form factors of the nucleon both in the space-like and time-like regions with constraints from other experiments, unitarity, and perturbative QCD. We give a brief introduction into dispersion theory for nucleon form factors and present first results from our ongoing form factor analysis. We also calculate the two-pion continuum contribution to the isovector spectral functions drawing upon the new hig...
Entropy behavior with nucleon-antinucleon asymmetry
Energy Technology Data Exchange (ETDEWEB)
Silva, J.B.; Delfino, A.; Malheiro, M. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica]. E-mail: jbsilva@if.uff.br
2003-07-01
The recent STAR Collaborations at RHIC found anti-proton-to-proton ratio about 0.6. Constraining the baryonic density to satisfy this experiment data, a set of hadronic models is studied to investigate the baryonic entropy per particle behaviour. We also investigate the baryonic chemical potential as a function of the anti-nucleon-nucleon ratio. Our results show a systematic increasing (decreasing) of the entropy per particle (baryonic chemical potential) as this ratio increases. (author)
Off-shell properties of the Paris nucleon-nucleon potential and implications for few-body systems
International Nuclear Information System (INIS)
We investigate the half-off-shell properties for the Paris nucleon-nucleon potential and for a separable representation of it. Deuteron bound-state and scattering wave functions as well as Noyes-Kowalski functions are considered. Essential features with respect to elastic electron-deuteron and nucleon-deuteron scattering are discussed. We find that some polarization observables of these processes dismiss certain off-shell behaviours encountered, for instance, in various phenomenological separable potentials
Chiral extrapolations for nucleon electric charge radii
Hall, J. M. M.; Leinweber, D. B.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia)
2013-01-01
Lattice simulations for the electromagnetic form factors of the nucleon yield insights into the internal structure of hadrons. The logarithmic divergence of the charge radius in the chiral limit poses an interesting challenge in achieving reliable predictions from finite-volume lattice simulations. Recent results near the physical pion mass are examined in order to confront the issue of how the chiral regime is approached. The electric charge radius of the nucleon presents a...
Measurement of the Electron Structure Function at LEP energies
Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, U; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W-D; Arnoud, Y; Ask, S; Asman, B; Augustin, J E; Augustinus, A; Baillon, P; Ballestrero, A; Bambade, P; Barbier, R; Bardin, D; Barker, G J; Baroncelli, A; Battaglia, M; Baubillier, M; Becks, K-H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N; Benvenuti, A; Berat, C; Berggren, M; Bertrand, D; Besancon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Bruckman, P; Brunet, J M; Buschbeck, B; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F; Chapkin, M; Charpentier, Ph; Checchia, P; Chierici, R; Chliapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D; Cuevas, J; D'Hondt, J; da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; De Boer, W; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; de Paula, L; Di Ciaccio, L; Di Simone, A; Doroba, K; Drees, J; Eigen, G; Ekelof, T; Ellert, M; Elsing, M; Espirito Santo, M C; Fanourakis, G; Fassouliotis, D; Feindt, M; Fernandez, J; Ferrer, A; Ferro, F; Flagmeyer, U; Foeth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J; Gandelman, M; Garcia, C; Gavillet, Ph; Gazis, E; Gokieli, R; Golob, B; Gomez-Ceballos, G; Goncalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Hoffman, J; Holmgren, S-O; Holt, P J; Houlden, M A; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Katsoufis, E; Kernel, G; Kersevan, B P; Kerzel, U; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kouznetsov, O; Krumstein, Z; Kucharczyk, M; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; Lopez, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Marechal, B; Margoni, M; Marin, J-C; Mariotti, C; Markou, A; Martinez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; Mc Nulty, R; Meroni, C; Migliore, E; Mitaroff, W; Mjoernmark, U; Moa, T; Moch, M; Moenig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Mueller, U; Muenich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, G; Myklebust, T; Nassiakou, M; Navarria, F; Nawrocki, K; Nemecek, S; Nicolaidou, R; Nikolenko, M; Oblakowska-Mucha, A; Obraztsov, V; Olshevski, A; Onofre, A; Orava, R; Osterberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, Th D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Pozdniakov, V; Pukhaeva, N; Pullia, A; Radojicic, D; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P; Richard, F; Ridky, J; Rivero, M; Rodriguez, D; Romero, A; Ronchese, P; Roudeau, P; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovsky, A; Salmi, L; Salt, J; Sander, C; Savoy-Navarro, A; Schwickerath, U; Sekulin, R; Siebel, M; Sisakian, A; Slominski, W; Smadja, G; Smirnova, O; Sokolov, A; Sopczak, A; Sosnowski, R; Spassov, T; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Szwed, J; Tabarelli, T; Tegenfeldt, F; Timmermans, J; Tkatchev, L; Tobin, M; Todorovova, S; Tome, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; Van Dam, P; Van Eldik, J; van Remortel, N; Van Vulpen, I; Vegni, G; Veloso, F; Venus, W; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O; Zalewska, A; Zalewski, P; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zintchenko, A; Zupan, M
2010-01-01
The hadronic part of the Electron Structure Function (ESF) has been measured for the first time, using e+e- data collected by the DELPHI experiment at LEP, at centre-of-mass energies sqrt(s) = 91.2-209.5 GeV. The data analysis is simpler than that of the measurement of the photon structure function. The ESF data are compared to predictions of phenomenological models based on the photon structure function. It is shown that the quasi-real photon virtuality contribution is significant. The presented data can serve as a cross-check of the photon structure function analyses and help in refining existing parametrizations.
SELEX is Structure-Function Studies of Cytokines
International Science & Technology Center (ISTC)
Exploiting of SELEX Procedure in Structure-Function Studies of Recombinant Human Cytokines and Their Natural and Synthetic Antagonists in Order to Create Artificial Immunomodulating Medical Preparations
3D-Fun: predicting enzyme function from structure
von Grotthuss, Marcin; Plewczynski, Dariusz; Vriend, Gert; Rychlewski, Leszek
2008-01-01
The ‘omics’ revolution is causing a flurry of data that all needs to be annotated for it to become useful. Sequences of proteins of unknown function can be annotated with a putative function by comparing them with proteins of known function. This form of annotation is typically performed with BLAST or similar software. Structural genomics is nowadays also bringing us three dimensional structures of proteins with unknown function. We present here software that can be used when sequence compari...
Analyzing protein structure and function using ancestral gene reconstruction
Harms, Michael J.; Thornton, Joseph W.
2010-01-01
Protein families with functionally diverse members can illuminate the structural determinants of protein function and the process by which protein structure and function evolve. To identify the key amino acid changes that differentiate one family member from another, most studies have taken a “horizontal” approach, swapping candidate residues between present-day family members. This approach has often been stymied, however, by the fact that shifts in function often require multiple interactin...
Simula, S
1996-01-01
The production of slow nucleons in semi-inclusive deep inelastic electron scattering off the deuteron is investigated in the region x > 0.3. It is shown that within the spectator mechanism the semi-inclusive cross section exhibits a scaling property even at moderate values of Q^2 (\\sim few (GeV/c)^2) accessible at present facilities, like CEBAF. Such a scaling property can be used as a model-independent test of the dominance of the spectator mechanism and provides an interesting tool to investigate the neutron structure function. The possibility of extracting model-independent information on the neutron to proton structure function ratio from semi-inclusive experiments is illustrated. The application of the spectator scaling to semi-inclusive processes off complex nuclei is outlined.
Disruption of structure–function coupling in the schizophrenia connectome
Directory of Open Access Journals (Sweden)
Luca Cocchi
2014-01-01
Full Text Available Neuroimaging studies have demonstrated that the phenomenology of schizophrenia maps onto diffuse alterations in large-scale functional and structural brain networks. However, the relationship between structural and functional deficits remains unclear. To answer this question, patients with established schizophrenia and matched healthy controls underwent resting-state functional and diffusion weighted imaging. The network-based statistic was used to characterize between-group differences in whole-brain functional connectivity. Indices of white matter integrity were then estimated to assess the structural correlates of the functional alterations observed in patients. Finally, group differences in the relationship between indices of functional and structural brain connectivity were determined. Compared to controls, patients with schizophrenia showed decreased functional connectivity and impaired white matter integrity in a distributed network encompassing frontal, temporal, thalamic, and striatal regions. In controls, strong interregional coupling in neural activity was associated with well-myelinated white matter pathways in this network. This correspondence between structure and function appeared to be absent in patients with schizophrenia. In two additional disrupted functional networks, encompassing parietal, occipital, and temporal cortices, the relationship between function and structure was not affected. Overall, results from this study highlight the importance of considering not only the separable impact of functional and structural connectivity deficits on the pathoaetiology of schizophrenia, but also the implications of the complex nature of their interaction. More specifically, our findings support the core nature of fronto-striatal, fronto-thalamic, and fronto-temporal abnormalities in the schizophrenia connectome.
Nucleon form factors, generalized parton distributions and quark angular momentum
Energy Technology Data Exchange (ETDEWEB)
Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kroll, Peter [Bergische Univ., Wuppertal (Germany). Fachbereich Physik; Regensburg Univ. (Germany). Institut fuer Theoretische Physik
2013-02-15
We extract the individual contributions from u and d quarks to the Dirac and Pauli form factors of the proton, after a critical examination of the available measurements of electromagnetic nucleon form factors. From this data we determine generalized parton distributions for valence quarks, assuming a particular form for their functional dependence. The result allows us to study various aspects of nucleon structure in the valence region. In particular, we evaluate Ji's sum rule and estimate the total angular momentum carried by valence quarks at the scale {mu}=2 GeV to be J{sup u}{sub v}=0.230{sup +0.009}{sub -0.024} and J{sup d}{sub v}=-0.004{sup +0.010}{sub -0.016}.
MRI in Optic Neuritis: Structure, Function, Interactions
DEFF Research Database (Denmark)
FuglØ, Dan
2011-01-01
Optic neuritis (ON) is an acute inflammatory demyelinating condition of the optic nerve characterised by transient visual loss and eye pain. ON is the presenting symptom in 20% of patients with multiple sclerosis (MS) and the 15 year risk of developing MS after ON is about 50%. Decline in vision usually occurs over several days and is accompanied by eye pain. Patients start to recover 2 to 4 weeks after onset and most of the recovery typically occurs within 6 months. However, despite clinical recovery, patients develop atrophy of the optic nerve, which has been demonstrated using magnetic resonance imaging (MRI), and the visual evoked potential (VEP) continues to show a delayed P100 indicating persistent demyelination. The explanation for this apparent discrepancy between structure and function could be due to either a redundancy in the visual pathways so that some degree of signal loss will have very few or no clinical symptoms, or it could be due to compensatory mechanisms in the visual pathway or thevisual cortex. In order to understand the pathophysiology and recovery processes in ON it is essential to have sensitive methods to asses both structure and function. These methods will also help in assessing disease progression, understanding the recovery processes and treatment efficiency in clinical trials with ON or MS patients. VEPs have been used in many years to measure the cortical response to visual stimuli in patients with ON and MS. However, the spatial resolution of VEPs are low. Functional MRI (fMRI) is a non-invasive technique that can measure brain activity with a high spatial resolution. Recently, technical and methodological advancements have made it feasible to record VEPs and fMRI simultaneously and the relationship between averaged VEPs and averaged fMRI signals have been described. Still, to take full advantage of simultaneously recorded VEP-fMRI one would ideally want to track single-trial changes in the VEP and use this information in the fMRI analysis. In order to do this weexamined 10 healthy volunteers with simultaneous VEP-fMRI. Different measures of single trial VEP fluctuations were calculated and their ability to predict the fMRI response was compared. Regressors based on peak amplitudes and alpha activity showed significant correlation with the fMRI response, thus allowing identification of visual areas in the fMRI analysis. These results are of particular interest in the study of ON patients where the neuronal response may be pathological. Instead of assuming a standard response during fMRI analysis, the actual neuronal response can be measured. In order to interpret changes in visual fMRI response during the course of ON, a measurement of the damage to the afferent visual pathway is needed. Optical coherence tomography (OCT) is a tissue imaging technique capable of measuring the RNFL thickness around the optic disc. We investigated the correlation between optic nerve lesion length, the RNFL thickness and the fMRI response in a group of 41 patients with ON. The most important finding was a positive correlation between RNFL thickness and fMRI response when examining the affected eyes of ON patients after 6 months (p < 0.001, r = 0.54). We conclude that RNFL thickness measured by OCT can be used as a measure of the change in visual neuronal input in recovered ON patients and is useful for modelling the fMRI response. We then examined a group of 60 acute ON patients using fMRI. They were examined at baseline, after 14, 90 and 180 days and were then compared to a control group of 19 healthy volunteers. This is by far the largest fMRI study of ON patients ever carried out. We found a reduced fMRI response in affected eyes at baseline. The fMRI response increased over time but remained below the response of control eyes. In addition we found signs of adaptive cortical activity in the visual cortex, indicating that the brain is able to compensate in part for the reduced visual input from the affected eye.
Neural network parametrization of deep-inelastic structure functions
International Nuclear Information System (INIS)
We construct a parametrization of deep-inelastic structure functions which retains information on experimental errors and correlations, and which does not introduce any theoretical bias while interpolating between existing data points. We generate a Monte Carlo sample of pseudo-data configurations and we train an ensemble of neural networks on them. This effectively provides us with a probability measure in the space of structure functions, within the whole kinematic region where data are available. This measure can then be used to determine the value of the structure function, its error, point-to-point correlations and generally the value and uncertainty of any function of the structure function itself. We apply this technique to the determination of the structure function F2 of the proton and deuteron, and a precision determination of the isotriplet combination F2[p-d]. We discuss in detail these results, check their stability and accuracy, and make them available in various formats for applications. (author)
Somà, V.; Barbieri, C.; Duguet, T.
2014-02-01
Background: The newly developed self-consistent Gorkov-Green's function approach represents a promising path to the ab initio description of mid-mass open-shell nuclei. The formalism based on a two-nucleon interaction and the second-order truncation of Gorkov's self-energy has been described in detail in Ref. [Somà, Duguet, and Barbieri, Phys. Rev. C 84, 064317 (2011), 10.1103/PhysRevC.84.064317]. Purpose: The objective is to discuss the methodology used to solve Gorkov's equation numerically and to gauge its performance in view of carrying out systematic calculations of medium-mass nuclei in the future. In doing so, different sources of theoretical error and degrees of self-consistency are investigated. Methods: We employ Krylov projection techniques with a multi-pivot Lanczos algorithm to efficiently handle the growth of poles in the one-body Green's function that arises as a result of solving Gorkov's equation self-consistently. We first characterize the numerical scaling of Gorkov's calculations based on full self-consistency and on a partially self-consistent scheme coined as "sc0". Using small model spaces, the Krylov projection technique is then benchmarked against exact diagonalization of the original Gorkov matrix. Next, the convergence of the results as a function of the number N? of Lanczos iterations per pivot is investigated in large model spaces. Eventually, the convergence of the calculations with the size of the harmonic oscillator model space is examined. Results: Gorkov self-consistent Green's function (SCGF) calculations performed on the basis of Krylov projection techniques display a favorable numerical scaling that authorizes systematic calculations of mid-mass nuclei. The Krylov projection selects efficiently the appropriate degrees of freedom while spanning a very small fraction of the original space. For typical large-scale calculations of mid-mass nuclei, a Krylov projection making use of N??50 yields a sufficient degree of accuracy on the observables of interest. The partially self-consistent sc0 scheme is shown to reproduce fully self-consistent solutions in small model spaces at the 1% level. Eventually, Gorkov-Green's function calculations performed on the basis of SRG-evolved interactions show a fast convergence as a function of the model-space size. Conclusions: The end result is a tractable, accurate and gently scaling ab initio scheme applicable to complete isotopic and isotonic chains in the medium-mass region. The partially self-consistent sc0 scheme provides an excellent compromise between accuracy and computational feasibility and will be the workhorse of systematic Gorkov-Green's function calculations in the future. The numerical scaling and performances of the algorithm employed offers the possibility (i) to apply the method to even heavier systems than those (e.g., 74Ni) already studied so far and (ii) to perform converged Gorkov SCGF calculations based on harder, e.g. original chiral interactions.
Corradi, Lorenzo
2015-10-01
Excitation functions of one- and two-neutron transfer channels have been measured for the 96Zr+40Ca and 116Sn+60Ni systems at bombarding energies ranging from the Coulomb barrier to ˜25% below. Target-like recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental transfer probabilities have been compared, in absolute values and in slope, with semiclassical microscopic calculations which incorporate nucleon-nucleon pairing correlations. For the first time in a heavy ion collision, one was able to provide a consistent description of one and two neutron transfer reactions by incorporating, in the reaction mechanism, all known structure information of entrance and exit channels nuclei. In particular, there is no need to introduce any enhancement factor for the description of two neutron transfer, of course very important are the correlations induced by the pairing interaction.
Nucleon-nucleon scattering phase shifts
International Nuclear Information System (INIS)
Here are presented 0 to 800 MeV nucleon-nucleon elastic and inelastic phase parameters derived by several groups: Arndt and Roper; Hoshizaki; Bugg; Bystricky, Lechanoine, and Lehar; and Bryan, Clark, and VerWest. Resonant-like behavior appears in the 1D2 and 3F3 states above the inelastic threshold in Hoshizaki's analysis but not in Arndt and Roper's. The np data are inadequate to permit determination of the I = O phase parameters above 600 MeV. 27 references
The relativistic Lagrangian: Nucleon-nucleon potential
Sahu, B. B.; Singh, S. K.; Bhuyan, M.; Patra, S. K.
2013-04-01
The microscopic origin of nucleon-nucleon (NN) potential is introduced as an alternative to the popular M3Y form for the first time using the relativistic mean field (RMF) theory with the non linear terms in ?-meson. Its applicability is examined with the study of cluster radioactivity by folding it with the RMF-densities of cluster and daughter nuclei to obtain the optical potential in the region of nuclides just above the double magic core 100Sn. The results obtained found comparable with the widely used M3Y NN interactions.
Determination of the longitudinal structure function FL at HERA
International Nuclear Information System (INIS)
Recent results from the HERA experiment H1 on the longitudinal structure function FL of the proton are presented. They include proton structure function analyses with particular emphasis on those kinematic regions which are sensitive to FL. All results can be consistently described within the framework of perturbative QCD. (author)
Structure-function relationships in methionine adenosyltransferases
Markham, George D.; Pajares, María A.
2009-01-01
Methionine adenosyltransferases (MAT) are the family of enzymes that synthesize the main biological methyl donor, S-adenosylmethionine. The high sequence conservation among catalytic subunits from bacteria and Eukarya preserves key residues that control activity and oligomerization, which is reflected in the protein structure. However, structural differences among complexes with substrates and products have led to proposals of several reaction mechanisms. In parallel, folding studies are star...
The value of structural and functional imaging in dementia
International Nuclear Information System (INIS)
Structural and functional diagnostic imaging provides a distinctive contribution of the clinical and differential diagnosis in dementia. Sensitive magnetic resonance techniques make the analysis of structural changes, brain atrophy and lesions of the cerebral parenchyma relatively simple, but a particular finding only has a low specificity. Magnetic resonance spectroscopy and innovative structural techniques, such as magnetization transfer ratio (MRG), diffusion tensor imaging (DTI) and functional magnetic resonance tomography, become increasingly important. Results of structural and functional diagnostic imaging are documented in reference to their diagnostic and differential therapeutic contribution to relevant dementias and are cautiously compared with the results of nuclear medicine. (orig.)
Photon structure function and Bc-meson production in ?? interactions
International Nuclear Information System (INIS)
The contribution of the photon c-quark structure function to Bc(Bc*)-meson production in ?? interactions is studied in the nonrelativistic quark model, in perturbative QCD, and in the model of vector-meson dominance. It is shown that the contribution of the photon structure function via the partonic subprocess c??Bc(Bc*)b is important both near the threshold of Bc(Bc*)-meson production - the region dominated by the contribution of the hadronic component of the photon structure function - and at high energies, where the cross section for Bc-meson production is determined only by the contribution from the pointlike component of the photon structure function. The contribution of the photon structure function to the cross section for Bc(Bc*)-meson production in e+e- collisions is predicted at LEP energies and above
Cottingham formula and nucleon polarisabilities
Energy Technology Data Exchange (ETDEWEB)
Gasser, J.; Leutwyler, H. [Universitaet Bern, Albert Einstein Center for Fundamental Physics, Institut fuer theoretische Physik, Bern (Switzerland); Hoferichter, M. [Universitaet Bern, Albert Einstein Center for Fundamental Physics, Institut fuer theoretische Physik, Bern (Switzerland); Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, ExtreMe Matter Institute EMMI, Darmstadt (Germany); University of Washington, Institute for Nuclear Theory, Seattle, WA (United States); Rusetsky, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Bonn (Germany)
2015-08-15
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections - provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon polarisabilities. We evaluate the sum rule for the difference between the electric polarisabilities of proton and neutron by means of the available parameterisations of the data and compare the result with experiment. (orig.)
Cottingham formula and nucleon polarizabilities
Gasser, J; Leutwyler, H; Rusetsky, A
2015-01-01
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections---provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon polarizabilities. We evaluate the sum rule for the difference between the electric polarizabilities of proton and neutron by means of the available parameterizations of the data and compare the result with experiment.
Radical Conservatism And Nucleon Decay
Wilczek, Frank
2000-01-01
Unification of couplings, observation of neutrino masses in the expectedrange, and several other considerations confirm central implications ofstraightforward gauge unification based on SO(10) or a close relative andincorporating low-energy supersymmetry. The remaining outstanding consequenceof this circle of ideas, yet to be observed, is nucleon instability. Clearly,we should aspire to be as specific as possible regarding the rate and form ofsuch instability. I argue that not only esthetics, but also the observedprecision of unification of couplings, favors an economical symmetry-breaking(Higgs) structure. Assuming this, one can exploit its constraints to buildreasonably economical, overconstrained yet phenomenologically viable models ofquark and lepton masses. Putting it all together, one arrives at reasonablyconcrete, hopeful expectations regarding nucleon decay. These expectations areneither ruled out by existing experiments, nor hopelessly inaccessible.
Disruption of structure–function coupling in the schizophrenia connectome
Cocchi, Luca; Harding, Ian H.; Lord, Anton; Pantelis, Christos; Yucel, Murat; Zalesky, Andrew
2014-01-01
Neuroimaging studies have demonstrated that the phenomenology of schizophrenia maps onto diffuse alterations in large-scale functional and structural brain networks. However, the relationship between structural and functional deficits remains unclear. To answer this question, patients with established schizophrenia and matched healthy controls underwent resting-state functional and diffusion weighted imaging. The network-based statistic was used to characterize between-group differences in wh...
Deuteron structure functions in the context of few-body physics
International Nuclear Information System (INIS)
Few-body systems offer a unique challenge to those interested in deep-inelastic scattering. Using the deuteron as the simplest and most easily solvable nuclear system we review the main physics issues in the valence and sea quark regimes. For the former the key issue is the understanding of Fermi motion and binding corrections, and our ability to extract the ratio F2n/F2p as x?1. The most recent analysis of deuteron data for F2n/F2p is consistent with perturbative QCD, but inconsistent with the assumptions common to all standard parton distribution fits. This should be taken into account in calculating event rates at HERA - especially at large x and Q2. The extraction of g1n also presents an opportunity to refine the description of nuclear effects in spin-dependent structure functions. In the region of small x one must correct for shadowing and meson exchange current effects to explore the flavor structure of sea, which is, in turn, deeply related to the chiral structure of the nucleon. (orig.)
The Pion-Cloud Contribution to the Electromagnetic Nucleon Form Factors
Kupelwieser, Daniel
2015-01-01
We study the electromagnetic structure of the nucleon within a hybrid constituent-quark model that comprises, in addition to the $3q$ valence component, also a $3q$+$\\pi$ non-valence component. To this aim we employ a Poincar\\'e-invariant multichannel formulation based on the point-form of relativistic quantum mechanics. With a simple 3-quark wave function for the bare nucleon, i.e. the $3q$-component, we obtain reasonable results for the nucleon form factors and predict the meson-cloud contribution to be significant only below $Q^2\\lesssim 0.5$\\,GeV$^2$ amounting to about 10\\% for $Q^2\\rightarrow 0$, in accordance with the findings of other authors.
Nodal Structure of the Electronic Wigner Function
DEFF Research Database (Denmark)
Schmider, Hartmut; Dahl, Jens Peder
1996-01-01
On the example of several atomic and small molecular systems, the regular behavior of nodal patterns in the electronic one-particle reduced Wigner function is demonstrated. An expression found earlier relates the nodal pattern solely to the dot-product of the position and the momentum vector, if both arguments are large. An argument analogous to the ``bond-oscillatory principle'' for momentum densities links the nuclear framework in a molecule to an additional oscillatory term in momenta parallel to bonds. It is shown that these are visible in the Wigner function in terms of characteristic nodes.
Bound nucleon dynamics in relativistic mean field theory and quasi-elastic electron scattering
International Nuclear Information System (INIS)
We compare results obtained with relativistic and non-relativistic bound nucleon wave functions on differential cross sections for electron induced one nucleon knock-out at quasi-elastic kinematics. We discuss the role of the negative-energy component of the relativistic bound nucleon wave functions and the issue of factorization of the differential cross section. (authors)
Quasielastic structure in the reaction 56Fe + 56Fe at 14.6 MeV/nucleon
International Nuclear Information System (INIS)
Indications that structure is enhanced for higher bombarding energies led to the study of the 56Fe+56Fe reaction at the Oak Ridge HHIRF using the 14.6 MeV/u 56Fe beam. Emphasis was placed on obtaining unit mass and charge resolution for all projectile-like products. The total kinetic energy spectra of the cobalt products detected at 30, 50 and 70 are shown. Several structures can be tentatively identified. The most striking feature is a strong peak corresponding to a total kinetic energy loss E/sub loss/=16-18 MeV (excitation energy E* of 12-14 MeV). While very prominent in the 50 and 70 spectra, this peak is not seen at 30 and may be interpreted as a proton transfer channel with an angular distribution characteristic of large angular momentum transfer. A second peak can clearly be identified at E/sub loss/ approx. 50 MeV for theta/sub lab/=50; however, a similar structure appears at E/sub loss/ approx. 45 MeV for 70 and there are indications of something at E/sub loss/ approx. 55 MeV for the 30 data. Evaporation calculations show that this is the region of feeding from the first sequential neutron evaporation of 58Co. Several other features are discernable at higher excitation energies which are difficult to understand in the framework of particle evaporation. While the results of the Z=27 energy spectra are encouraging, separation of the 50 data into spectra for individual cobalt isotopes does not greatly enhance the structure. The angular distributions of the four peaks defined by the 70 spectrum are plotted for 20 MeV bins in E/sub loss/. The lowest excitation energy bin, encompassing the E*=15 MeV structure, has an angular distribution which appears to be bell-shaped while the other excitation energy peaks become progressively more forward peaked with increasing excitation energy
Structural and functional imaging: Particularities in children
Energy Technology Data Exchange (ETDEWEB)
Chiron, C.; Hertz-Pannier, L. [Hop Necker Enfants Malad, INSERM, Serv Neuropediat, U663, F-75015 Paris (France); Chiron, C.; Hertz-Pannier, L. [UnivParis 05, F-75005 Paris (France); Chiron, C.; Hertz-Pannier, L. [CEA, I2BM, Neurospin, SHFJ, F-91191 Orsay (France)
2008-07-01
Surgery of partial epilepsies in childhood has largely benefited from the recent advances of imaging techniques, which carry a triple goal: (1) to contribute to the localization of the epilepsy onset zone, (2) to detect and delineate an underlying lesion, and (3) to study the spatial relationship between the epileptogenic zone and the neighboring functional cortex, in order to select patients and plan the resection. This noninvasive pre-surgical imaging workup must be compared to clinical and electrical data to estimate the postoperative prognosis, while invasive techniques such as SEEG, cortical stimulations, and IAT often remain indispensable in difficult cases, i.e., in cryptogenic epilepsies. As in adults, advances in MRI allow us to detect more and more subtle underlying lesions, but this requires repeating MR studies during early childhood and using adapted sequence parameters to account for ongoing myelination. Ictal SPECT and PET imaging prove especially useful in planning depth electrode placement when video-EEG is not contributive, when MRI looks normal or shows multiple abnormalities, or in cases of discrepant findings. Multimodal imaging greatly enhances the sensitivity of all of these techniques. Finally, functional MRI of motor and language functions provide noninvasive cortical mapping of essential functions, using age-adapted paradigms, in cooperating children from age five to six and from IQs around 60. (authors)
Structural and Functional Studies of Archaeal Viruses*
Lawrence, C. Martin; Menon, Smita; Eilers, Brian J.; Bothner, Brian; Khayat, Reza; Douglas, Trevor; Young, Mark J.
2009-01-01
Viruses populate virtually every ecosystem on the planet, including the extreme acidic, thermal, and saline environments where archaeal organisms can dominate. For example, recent studies have identified crenarchaeal viruses in the hot springs of Yellowstone National Park and other high temperature environments worldwide. These viruses are often morphologically and genetically unique, with genomes that show little similarity to genes of known function, complicating eff...
Phosphatidylinositol 4-kinases: Function, structure, and inhibition.
Czech Academy of Sciences Publication Activity Database
Bou?a, Evžen; Nencka, Radim
2015-01-01
Ro?. 337, ?. 2 (2015), s. 136-145. ISSN 0014-4827 EU Projects: European Commission(XE) 333916 Institutional support: RVO:61388963 Keywords : phosphatidylinositol 4-kinase * inhibitor * crystal structure * virus Subject RIV: CC - Organic Chemistry Impact factor: 3.246, year: 2014
Types and Functions of Coastal Structures
Burcharth, H. F.; A. Hughes, Steven
2005-01-01
Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives include sheltering of harbour basins and harbour entrances against waves, stabilization of navigation channels at inlets, and protection of water intakes and outfalls.
Types and Functions of Coastal Structures
DEFF Research Database (Denmark)
Burcharth, H. F.; A. Hughes, Steven
2003-01-01
Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives include sheltering of harbour basins and harbour entrances against waves, stabilization of navigation channels at inlets, and protection of water intakes and outfalls.
Alternative interpretation of structure function F2?.
Czech Academy of Sciences Publication Activity Database
Hejbal, Ji?í
179-180, ?. 8 (2008), 62-68. ISSN 0920-5632 R&D Projects: GA MŠk LC527 Institutional research plan: CEZ:AV0Z10100502 Keywords : quantum chromodynamics * photon structure * perturbative theory Subject RIV: BF - Elementary Particles and High Energy Physics
On a useful functional representation of control system structure
Malchow, Harvey L.
1988-01-01
An alternative structure for control systems is proposed. The structure is represented by a three-element block diagram and three functional definitions. It is argued that the three functional elements form a canonical set. The set includes the functions description, estimation and control. General overlay of the structure on parallel state and nested-state control systems is discussed. Breakdown of two real nested-state control systems into the proposed functional format is displayed. Application of the process to the mapping of complex control systems R and D efforts is explained with the Mars Rover Sample and Return mission as an example. A previous application of this basic functional structure to Space Station performance requirements organization is discussed.
Structure-function relationships of immunostimulatory polysaccharides: A review.
Ferreira, Sónia S; Passos, Cláudia P; Madureira, Pedro; Vilanova, Manuel; Coimbra, Manuel A
2015-11-01
Immunostimulatory polysaccharides are compounds capable of interacting with the immune system and enhance specific mechanisms of the host response. Glucans, mannans, pectic polysaccharides, arabinogalactans, fucoidans, galactans, hyaluronans, fructans, and xylans are polysaccharides with reported immunostimulatory activity. The structural features that have been related with such activity are the monosaccharide and glycosidic-linkage composition, conformation, molecular weight, functional groups, and branching characteristics. However, the establishment of structure-function relationships is possible only if purified and characterized polysaccharides are used and selective structural modifications performed. Aiming at contributing to the definition of the structure-function relationships necessary to design immunostimulatory polysaccharides with potential for preventive or therapeutical purposes or to be recognized as health-improving ingredients in functional foods, this review introduces basic immunological concepts required to understand the mechanisms that rule the potential claimed immunostimulatory activity of polysaccharides and critically presents a literature survey on the structural features of the polysaccharides and reported immunostimulatory activity. PMID:26256362
Joint Modelling of Structural and Functional Brain Networks
DEFF Research Database (Denmark)
Andersen, Kasper Winther; Herlau, Tue
Functional and structural magnetic resonance imaging have become the most important noninvasive windows to the human brain. A major challenge in the analysis of brain networks is to establish the similarities and dissimilarities between functional and structural connectivity. We formulate a non-parametric Bayesian network model which allows for joint modelling and integration of multiple networks. We demonstrate the model’s ability to detect vertices that share structure across networks jointly in functional MRI (fMRI) and diffusion MRI (dMRI) data. Using two fMRI and dMRI scans per subject, we establish significant structures that are consistently shared across subjects and data splits. This provides an unsupervised approach for modeling of structure-function relations in the brain and provides a general framework for multimodal integration.
International Nuclear Information System (INIS)
Final data measured with the EMC forward spectrometer are presented on the production of forward charged hardons in ?p and ?d scattering at incident beam energies between 100 and 280 GeV. The large statistics of 373 000 events allows a study of the semi-inclusive hadron production as a function of z, pT2 and T2> in small Q2, xBj and W bins. Charge multiplicity ratios and differences as a function of z and xBj are given for p, d and n-targets. From the differences of charge multiplicities the ratio of the valence quark distributions of the proton dv(x)/uv(x) is determined for the first time in charged lepton scattering. The Gronau et al. sum rule is tested, the measured sum being 0.31±0.06 stat.±0.05 syst., compared with the theoretical expectation of 2/7?0.286. The measured sum corresponds to an absolute value of the ratio of the d and u quark charge of 0.44±0.10 stat.±0.08 syst. (orig.)
Polarized light ions and spectator nucleon tagging at EIC
Energy Technology Data Exchange (ETDEWEB)
Guzey, Vadim [Petersburg Nuclear Physics Institute, Gatchina, 188300, Russia; Higinbotham, Dougas W. [JLAB; Hyde, Charles [Old Dominion University, Norfolk, VA 23529, USA; Nadel-Turonski, Pawel A. [JLAB; Park, Kijun [Old Dominion University, Norfolk, VA 23529, USA; Sargsian, Misak M. [Florida International University, Miami, FL 33199, USA; Strikman, Mark [Pennsylvania State University, University Park, PA 16802, USA; Weiss, Christian [JLAB
2014-10-01
The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x ll 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < p(R) < several 100MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.
Yao, J M; Meng, J
2014-01-01
A study of 4$\\alpha$ linear-chain structure (LCS) in high-lying collective excitation states of $^{16}$O with a covariant density functional theory is presented. The low-spin states are obtained by configuration mixing of particle-number and angular-momentum projected quadrupole deformed mean-field states with generator coordinate method (GCM). The high-spin states are determined by cranking calculations. These two calculations are based on the same energy density functional PC-PK1. We have found the LCS candidate in both high-lying low-spin GCM states and cranking high-spin states with similar moment of inertia and band-head energy, which are estimated to be around 0.11 MeV and 30 MeV, respectively. The intrinsic configuration is considered to be the one that 4$\\alpha$ clusters stay along a common axis and nucleons occupy the $(s)^4(p)^4(d)^4(f)^4$ configurations in a nonlocal way. Moreover, our results indicate that the spin and orbital angular momenta of all nucleons are parallel in the LCS states but the ...
Structure of DNA-Functionalized Dendrimer Nanoparticles
Kumar, Mattaparthi Venkata Satish; Maiti, Prabal K
2012-01-01
Atomistic molecular dynamics simulations have been carried out to reveal the characteristic features of ethylenediamine (EDA) cored protonated poly amido amine (PAMAM) dendrimers of generation 3 (G3) and 4 (G4) that are functionalized with single stranded DNAs (ssDNAs). The four ssDNA strands that are attached via alkythiolate [-S (CH2)6-] linker molecule to the free amine groups on the surface of the PAMAM dendrimers observed to undergo a rapid conformational change during ...
Correlating structure and function for nanoparticle catalysts
Henkelman, Graeme
2014-03-01
Better oxygen reduction catalysts are needed to improve the efficiency and lower the cost of fuel cells. Metal nanoparticles are good candidates for new catalysts because their catalytic properties are different from bulk metals, and are sensitive to particle size, shape and composition. The electronic structure can be determined for small particles, making it possible to optimize particles for a desired reaction. Here, we calculate the electronic structure of 1 nm core/shell particles and show how the energy of electrons in the shell can tune the binding of oxygen by varying the core metal. Transition state calculations for O2 dissociation on the nanoparticle surface show that the d-band center is a good measure of the activation and reaction energies. Two factors are found to be significant for determining the catalytic activity of small nanoparticles; charge transfer in core/shell particles and the rigidity of alloy particles.
Structural and Functional Genomics of Tomato
Luigi Frusciante; Silvana Grandillo; Giovanni Giuliano; Maria Raffaella Ercolano; Maria Luisa Chiusano; Amalia Barone
2008-01-01
Tomato (Solanum lycopersicum L.) is the most intensively investigated Solanaceous species both in genetic and genomics studies. It is a diploid species with a haploid set of 12 chromosomes and a small genome (950Ã¢Â€Â‰Mb). Based on the detailed knowledge on tomato structural genomics, the sequencing of the euchromatic regions started in the year 2005 as a common effort of different countries. The manuscript focuses on markers used for tomato, on mapping efforts mainly based on exploitation o...
Structure and Function of Complex Modular Networks
Reichardt, Joerg
2006-01-01
A method for community detection (graph clustering) is developed by mapping the problem onto finding the ground state of an infinite range spin glass. A precise definition of community as maximally cohesive subgraph is derived from the properties of the ground state. Overlapping and hierarchical cluster structures are detected via changes of a single parameter. The ground state of the infinite range spin glass can be found by using computationally efficient methods operating on the sparse lin...
Structure-function relationships in telomerase genes.
Czech Academy of Sciences Publication Activity Database
Sýkorová, Eva; Fajkus, Ji?í
2009-01-01
Ro?. 101, ?. 7 (2009), s. 375-392. ISSN 0248-4900 R&D Projects: GA AV ?R(CZ) IAA600040505; GA AV ?R(CZ) IAA500040801; GA MŠk(CZ) LC06004 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : telomerase * alternative splicing * gene structure Subject RIV: BO - Biophysics Impact factor: 3.974, year: 2009
Ecto-5’-nucleotidase: Structure function relationships
Sträter, Norbert
2006-01-01
Ecto-5’-nucleotidase (ecto-5’-NT) is attached via a GPI anchor to the extracellular membrane, where it hydrolyses AMP to adenosine and phosphate. Related 5’-nucleotidases exist in bacteria, where they are exported into the periplasmic space. X-ray structures of the 5’-nucleotidase from E. coli showed that the enzyme consists of two domains. The N-terminal domain coordinates two catalytic divalent metal ions, whereas the C-terminal domain provides the substrate specificity pocket for the nucle...
Directory of Open Access Journals (Sweden)
2005-08-01
Full Text Available The bias in protein structure and function space resulting from experimental limitations and targeting of particular functional classes of proteins by structural biologists has long been recognized, but never continuously quantified. Using the Enzyme Commission and the Gene Ontology classifications as a reference frame, and integrating structure data from the Protein Data Bank (PDB, target sequences from the structural genomics projects, structure homology derived from the SUPERFAMILY database, and genome annotations from Ensembl and NCBI, we provide a quantified view, both at the domain and whole-protein levels, of the current and projected coverage of protein structure and function space relative to the human genome. Protein structures currently provide at least one domain that covers 37% of the functional classes identified in the genome; whole structure coverage exists for 25% of the genome. If all the structural genomics targets were solved (twice the current number of structures in the PDB, it is estimated that structures of one domain would cover 69% of the functional classes identified and complete structure coverage would be 44%. Homology models from existing experimental structures extend the 37% coverage to 56% of the genome as single domains and 25% to 31% for complete structures. Coverage from homology models is not evenly distributed by protein family, reflecting differing degrees of sequence and structure divergence within families. While these data provide coverage, conversely, they also systematically highlight functional classes of proteins for which structures should be determined. Current key functional families without structure representation are highlighted here; updated information on the "most wanted list" that should be solved is available on a weekly basis from http://function.rcsb.org:8080/pdb/function_distribution/index.html.
Cellular regulation of the structure and function of aortic valves
Directory of Open Access Journals (Sweden)
Ismail El-Hamamsy
2010-01-01
Full Text Available The aortic valve was long considered a passive structure that opens and closes in response to changes in transvalvular pressure. Recent evidence suggests that the aortic valve performs highly sophisticated functions as a result of its unique microscopic structure. These functions allow it to adapt to its hemodynamic and mechanical environment. Understanding the cellular and molecular mechanisms involved in normal valve physiology is essential to elucidate the mechanisms behind valve disease. We here review the structure and developmental biology of aortic valves; we examine the role of its cellular parts in regulating its function and describe potential pathophysiological and clinical implications.
Deep inelastic structure functions in the chiral bag model
International Nuclear Information System (INIS)
We calculate the structure functions for deep inelastic scattering on baryons in the cavity approximation to the chiral bag model. The behavior of these structure functions is analyzed in the Bjorken limit. We conclude that scaling is satisfied, but not Regge behavior. A trivial extension as a parton model can be achieved by introducing the structure function for the pion in a convolution picture. In this extended version of the model not only scaling but also Regge behavior is satisfied. Conclusions are drawn from the comparison of our results with experimental data. (orig.)
Kanazawa, K.; Lorcé, C.; Metz, A.; Pasquini, B.; Schlegel, M.
2014-07-01
Generalized transverse-momentum dependent parton distributions (GTMDs) encode the most general parton structure of hadrons. Here we focus on two twist-2 GTMDs which are denoted by F1,4 and G1,1 in parts of the literature. As already shown previously, both GTMDs have a close relation to orbital angular momentum of partons inside a hadron. However, recently even the mere existence of F1,4 and G1,1 has been doubted. We explain why this claim does not hold. We support our model-independent considerations by calculating the two GTMDs in the scalar diquark model and in the quark-target model, where we also explicitly check the relation to orbital angular momentum. In addition, we compute F1,4 and G1,1 at large transverse momentum in perturbative quantum chromodynamics and show that they are nonzero.
Nucleon QCD sum rules in nuclear matter including four-quark condensates
Drukarev, E G; Sadovnikova, V A; Gutsche, T; Faessler, A; Gutsche, Th.; Faessler, Amand
2004-01-01
We calculate the nucleon parameters in nuclear matter using the QCD sum rules approach in Fermi gas approximation. Terms up to 1/q^2 in the operator product expansion (OPE) are taken into account. The higher moments of the nucleon structure functions are included. The complete set of the nucleon expectation values of the four-quark operators is employed. Earlier the lack of information on these values has been the main obstacle for the further development of the approach. We show that the four-quark condensates provide the corrections of the order 20% to the results obtained in the leading orders of the OPE. This is consistent with the assumption about the convergence of the OPE. The nucleon vector self-energy \\Sigma_v and the nucleon effective mass m^* are expressed in terms of the in-medium values of QCD condensates. The numerical results for these parameters at the saturation value of the density agree with those obtained by the methods of nuclear physics.
Factor structure of functional state of primary school age children
Directory of Open Access Journals (Sweden)
Davidenko O.V.
2011-02-01
Full Text Available The examination of primary school children to determine the ranking of significant factors that determine the structure of their functional state depending on the level of physical health. It is shown that the main factor in the structure of the functional state of younger schoolchildren in low-and lower-middle level of physical fitness is selected morpho-functional status, which characterizes the functions of the body at rest. For children with average or above average level of physical fitness is a leading factor in physical fitness of schoolchildren.
Turner syndrome: neuroimaging findings: structural and functional.
LENUS (Irish Health Repository)
Mullaney, Ronan
2009-01-01
Neuroimaging studies of Turner syndrome can advance our understanding of the X chromosome in brain development, and the modulatory influence of endocrine factors. There is increasing evidence from neuroimaging studies that TX individuals have significant differences in the anatomy, function, and metabolism of a number of brain regions; including the parietal lobe; cerebellum, amygdala, hippocampus; and basal ganglia; and perhaps differences in "connectivity" between frontal and parieto-occipital regions. Finally, there is preliminary evidence that genomic imprinting, sex hormones and growth hormone have significant modulatory effects on brain maturation in TS.
Registering functional defects into periodic holographic structures.
Lutkenhaus, Jeff; George, David; Lowell, David; Arigong, Bayaner; Zhang, Hualiang; Lin, Yuankun
2015-08-10
In this paper, we present two methods for registering desired defect lattices within background periodic lattices through spatial light-modulator-based holographic lithography. In the first method, the diffraction efficiency from the engineered phase pattern was used to locally modify the fill fraction of polymerized materials in holographic structures, and, at the same time, we achieved the lattice matching between modified and background regions. In the second method, we registered spatially variant lattices for a 90 deg bend within the background periodic lattices through two steps of phase engineering of the laser beam. PMID:26368368
Pade spectroscopy of structural correlation functions: application to liquid gallium
Chtchelkatchev, N M; Ryltsev, R E; Khusnutdinoff, R M; Mokshin, A V
2015-01-01
We propose the new method of fluid structure investigation which is based on numerical analytical continuation of structural correlation functions with Pade approximants. The method particularly allows extracting hidden structural features of non-ordered condensed matter systems from experimental diffraction data. The method has been applied to investigating the local order of liquid gallium which has non-trivial stricture in both the liquid and solid states. Processing the correlation functions obtained from molecular dynamic simulations, we show the method proposed reveals non-trivial structural features of liquid gallium such as the spectrum of length-scales and the existence of different types of local clusters in the liquid.
Comparative study of neutron and nuclear matter with simplifi ed Argonne nucleon-nucleon potentials
Rios Huguet, A; Baldo, M; Polls, A.; Schulze, H-J; Vidana, I.
2012-01-01
We present calculations of the energy per particle of pure neutron and symmetric nuclear matter with simplified Argonne nucleon-nucleon potentials for different many-body theories. We compare critically the Brueckner-Hartree-Fock results to other formalisms, such as the Brueckner-Bethe-Goldstone expansion up to third order, self-consistent Green's functions, auxiliary field diffusion Monte Carlo, and Fermi hypernetted chain. We evaluate the importance of spin-orbit and tensor correlations in ...
Comparative study of neutron and nuclear matter with simplified Argonne nucleon-nucleon potentials
Baldo, M; Polls, A.; Rios, A.; Schulze, H. -J.; Vidana, I.
2012-01-01
We present calculations of the energy per particle of pure neutron and symmetric nuclear matter with simplified Argonne nucleon-nucleon potentials for different many-body theories. We compare critically the Brueckner-Hartree-Fock results to other formalisms, such as the Brueckner-Bethe-Goldstone expansion up to third order, Self-Consistent Green's Functions, Auxiliary Field Diffusion Monte Carlo, and Fermi Hyper Netted Chain. We evaluate the importance of spin-orbit and tens...
Structural and functional analysis of rice genome
Indian Academy of Sciences (India)
Akhilesh K. Tyagi; Jitendra P. Khurana; Paramjit Khurana; Saurabh Raghuvanshi; Anupama Gaur; Anita Kapur; Vikrant Gupta; Dibyendu Kumar; V. Ravi; Shubha Vij; Parul Khurana; Sulabha Sharma
2004-04-01
Rice is an excellent system for plant genomics as it represents a modest size genome of 430 Mb. It feeds more than half the population of the world. Draft sequences of the rice genome, derived by whole-genome shotgun approach at relatively low coverage (4–6 X), were published and the International Rice Genome Sequencing Project (IRGSP) declared high quality (>10 X), genetically anchored, phase 2 level sequence in 2002. In addition, phase 3 level finished sequence of chromosomes 1, 4 and 10 (out of 12 chromosomes of rice) has already been reported by scientists from IRGSP consortium. Various estimates of genes in rice place the number at > 50,000. Already, over 28,000 full-length cDNAs have been sequenced, most of which map to genetically anchored genome sequence. Such information is very useful in revealing novel features of macro- and micro-level synteny of rice genome with other cereals. Microarray analysis is unraveling the identity of rice genes expressing in temporal and spatial manner and should help target candidate genes useful for improving traits of agronomic importance. Simultaneously, functional analysis of rice genome has been initiated by marker-based characterization of useful genes and employing functional knock-outs created by mutation or gene tagging. Integration of this enormous information is expected to catalyze tremendous activity on basic and applied aspects of rice genomics.
Piezo channels: from structure to function.
Volkers, Linda; Mechioukhi, Yasmine; Coste, Bertrand
2015-01-01
Mechanotransduction is the conversion of mechanical stimuli into biological signals. It is involved in the modulation of diverse cellular functions such as migration, proliferation, differentiation, and apoptosis as well as in the detection of sensory stimuli such as air vibration and mechanical contact. Therefore, mechanotransduction is crucial for organ development and homeostasis and plays a direct role in hearing, touch, proprioception, and pain. Multiple molecular players involved in mechanotransduction have been identified in the past, among them ion channels directly activated by cell membrane deformation. Most of these channels have well-established roles in lower organisms but are not conserved in mammals or fail to encode mechanically activated channels in mammals due to non-conservation of mechanotransduction property. A family of mechanically activated channels that counts only two members in human, piezo1 and 2, has emerged recently. Given the lack of valid mechanically activated channel candidates in mammals in the past decades, particular attention is given to piezo channels and their potential roles in various biological functions. This review summarizes our current knowledge on these ion channels. PMID:25037583
International Nuclear Information System (INIS)
The behavior of a nucleon in nuclear medium is discussed in Chiral Color Dielectric Model. It is assumed that the nucleons in nuclear medium produces a background dielectric field and the quark and dielectric field equations are solved self consistently in presence of the dielectric field. A nucleon in nuclear medium is then constructed by means of standard procedure followed in chiral bag models. The corrections due to center of mass motion, color magnetic interaction and meson interaction are included. The calculations show that the nucleon becomes bigger in the medium but its mass does not change much. It is found that beyond a certain density, bound solutions in which quarks are bound in self-generated dielectric field are not possible. Thus, the calculations indicate that there is a critical density beyond which the matter consists of deconfined quarks. (author)
De Sanctis, M; Santopinto, E; Vassallo, A
2015-01-01
The relativized hypercentral Constituent Quark Model is used for the calculation of the elastic electromagnetic form factors of the nucleon. The results are compared with the recent measurements at Jlab.
Nucleon mean-free path in the medium
Somà V.; Rios A
2014-01-01
A microscopic determination of the mean-free path of a nucleon in symmetric nuclear matter is presented. Calculations are based on self-consistent Green’s functions theory within the ladder approximation and use dierent realistic nucleon-nucleon potentials supplemented by semi-phenomenological three-body forces. Temperature and density dependence are discussed. At zero temperature and nuclear saturation density we find that, for energies above 50 MeV, a nucleon has a mean-free path of 4 to...
Energy Technology Data Exchange (ETDEWEB)
Bedlinskiy, Ivan; Niccolai, Silvia; Stoler, Paul; Adhikari, Krishna; Aghasyan, Mher; Amaryan, Moskov; Anghinolfi, Marco; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bennett, Robert; Biselli, Angela; Bookwalter, Craig; Boyarinov, Sergey; Briscoe, William; Brooks, Williams; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Contalbrigo, Marco; Crede, Volker; D& #x27; Angelo, Annalisa; Daniel, Aji; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fegan, Stuart; Fleming, Jamie; Forest, Tony; Garcon, Michel; Gevorgyan, Nerses; Giovanetti, Kevin; Girod, Francoi-Xavier; Gohn, Wesley; Gothe, Ralf; Graham, Lewis; Griffioen, Keith; Guegan, Baptiste; Guidal, Michel; Guo, Lei; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Heddle, David; Hicks, Kenneth; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Jo, Hyon-Suk; Joo, Kyungseon; Keller, Dustin; Khanddaker, Mahbubul; Khertarpal, Puneet; Kim, Andrey; Kim, Wooyoung; Klein, Franz; Koirala, Suman; Kubarovsky, A; Kuhn, Sebastian; Kuleshov, Sergey; Kvaltine, Nicholas; Livingston, Kenneth; Lu, Haiyun; MacGregor, Ian; Mao, Yuqing; Markov, Nikolai; Martinez, D; Mayer, Michael; McKinnon, Bryan; Meyer, Curtis; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Moutarde, Herve; Munevar Espitia, Edwin; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niculescu, Gabriel; Niculescu, Maria-Ioana; Osipenko, Mikhail; Ostrovidov, Alexander; Pappalardo, Luciano; Permuzyan, Rafayel; Park, Kijun; Park, Sungkyun; Pasyuk, Eugene; Pereira, Sergio; Phelps, Evan; Pisano, Silvia; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Prok, Yelena; Protopopescu, Dan; Puckett, Andrew; Raue, Brian; Ricco, Giovanni; Rimal, Dipak; Ripani, Marco; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Saylor, Nicholas; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Seraydaryan, Heghine; Sharabian, Youri; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Samuel; Strauch, Steffen; Taiuti, Mauro; Tang, Wei; Taylor, Charles; Tian, Ye; Tkachenko, Svyatoslav; Ungaro, Maurizio; Vineyard, Michael; Vlasov, Alexander; Voskanyan, Hakob; Voutier, Eric; Walford, Natalie; Watts, Daniel; Weinstein, Lawrence; Weygan, Dennis; Wood, Michael; Zachariou, Nicholas; Zhang, Jixie; Zhao, Zhiwen
2012-09-01
Exclusive $\\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\\phi_\\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\\sigma_T +\\epsilon \\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\\sigma_T +\\epsilon \\sigma_L$ and fails to account for $\\sigma_{TT}$ and $\\sigma_{LT}$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive $\\pi^0$ electroproduction offers direct experimental access to the transversity GPDs.
Bedlinskiy, I; Niccolai, S; Stoler, P; Adhikari, K P; Aghasyan, M; Amaryan, M J; Anghinolfi, M; Avakian, H; Baghdasaryan, H; Ball, J; Baltzell, N A; Battaglieri, M; Bennett, R P; Biselli, A S; Bookwalter, C; Boiarinov, S; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Contalbrigo, M; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Doughty, D; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Fleming, J A; Forest, T A; Garçon, M; Gevorgyan, N; Giovanetti, K L; Girod, F X; Gohn, W; Gothe, R W; Graham, L; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jo, H S; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, F J; Koirala, S; Kubarovsky, A; Kuhn, S E; Kuleshov, S V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I J D; Mao, Y; Markov, N; Martinez, D; Mayer, M; McKinnon, B; Meyer, C A; Mineeva, T; Mirazita, M; Mokeev, V; Moutarde, H; Munevar, E; Camacho, C Munoz; Nadel-Turonski, P; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Pappalardo, L L; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Pereira, S Anefalos; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Rossi, P; Sabatié, F; Saini, M S; Salgado, C; Saylor, N; Schott, D; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tian, Ye; Tkachenko, S; Ungaro, M; Vineyard, M F; Vlassov, A; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zachariou, N; Zhang, J; Zhao, Z W; Zonta, I
2012-01-01
Exclusive $\\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\\phi_\\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\\sigma_T +\\epsilon \\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\\sigma_T +\\epsilon \\sigma_L$ and fails to account for $\\sigma_{TT}$ and $\\sigma_{LT}$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm ...
STRUCTURAL AND FUNCTIONAL MODEL OF MODERN POLITICAL MYTH
A.B. Chablin
2011-01-01
In this paper, based on comparative analysis of theoretical concepts and practical models of myths in the social-humanitarianknowledge, refine the structure of modern political myth, defining its functional role in the political process of postmodern society.
A Diels-Alder Route to Angularly Functionalized Bicyclic Structures
Kim, Woo Han; Lee, Jun Hee; Aussedat, Baptiste; Danishefsky, Samuel J
2010-01-01
A Diels-Alder based route to trans-fused angularly functionalized bicyclic structures has been developed. This transformation features the use of a tetrasubstituted dienophile in the cycloaddition step.
Small catalytic RNA: Structure, function and application
Energy Technology Data Exchange (ETDEWEB)
Monforte, J.A.
1991-04-01
We have utilized a combination of photochemical cross-linking techniques and site-directed mutagenesis to obtain secondary and tertiary structure information for the self-cleaving, self-ligating subsequence of RNA from the negative strand of Satellite Tobacco Ringspot Virus. We have found that the helical regions fold about a hinge to promoting four different possible tertiary interactions, creating a molecular of similar shape to a paperclip. A model suggesting that the ``paperclip`` and ``hammerhead`` RNAs share a similar three dimensional structure is proposed. We have used a self-cleaving RNA molecule related to a subsequence of plant viroids, a ``hammerhead,`` to study the length-dependent folding of RNA produced during transcription by RNA polymerase. We have used this method to determine the length of RNA sequestered within elongating E. coli and T7 RNA polymerase complexes. The data show that for E. coli RNA polymerase 12{plus_minus}1 nucleotides are sequestered within the ternary complex, which is consistent with the presence of an RNA-DNA hybrid within the transcription bubble, as proposed by others. The result for T7 RNA polymerase differs from E. coli RNA polymerase, with only 10{plus_minus}1 nucleotides sequestered within the ternary complex, setting a new upper limit for the minimum RNA-DNA required for a stable elongating complex. Comparisons between E. coli and T7 RNA polymerase are made. The relevance of the results to models or transcription termination, abortive initiation, and initiation to elongation mode transitions are discussed.