International Nuclear Information System (INIS)
In this talk I summarize ideas and plans which have been put forward by members of all collaborations running muon or neutrino experiments at CERN. During our discussions there was general agreement that: i) substantial improvements of structure function measurements in the SPS range are still possible and necessary and ii) it is the responsibility of the present groups and of CERN to provide a ''final'' set of structure functions in the present energy range. (orig.)
Eisele, F.
1998-01-01
New structure function measurements from fixed target experiments and especially HERA are reviewed. The extraction of parton distributions from these measurements is discussed with special emphasis on systematic problems. Finally the present uncertainty of our knowledge on parton distributions and on the strong coupling constant from DIS are dicussed.
Structure functions in the three nucleon system
International Nuclear Information System (INIS)
In this thesis, we study the structure functions, both polarised and unpolarized, of the three nucleon system and how they can give us information on two aspects of nuclear physics. First, we examine how to extract information on the free neutron structure functions and secondly we ask how does the nucleon's structure change in nuclei. Starting from a non-relativistic wave function for the three nucleon system, we use the standard convolution formalism to produce both polarised and unpolarized structure functions of 3He and 3H. In the unpolarized case we demonstrate a new way of extracting the unpolarized structure function F2 of the neutron from the measurement of the EMC effects in both 3He and 3H. In the polarised case we discuss how close an approximation g13He is to g1n??0. We also study the different corrections which must be included to obtain the best possible estimate for g1n??0. In this case we study the nuclear effects included in the convolution formalism, the contribution of the Delta-resonance and novel off-shell corrections to the free structure functions inside 3He computed in QMC (Quark Meson Coupling model). With respect to the effects of the nuclear medium on nucleons, this thesis presents estimates of the EMC effect in both 3He and 3H and of the nuclear medium on the Go and of the nuclear medium on the Gottfried sum rule. Finally, we present a clear signature of off-shell effects on the proton inside 3H. In this case off-shell corrections from QMC have been used but the results show that a variety of off-shell effects are, in fact, enhanced by the convolution formalism and consequently, can be similarly identified. (author)
Structure functions for the three nucleon system
Bissey, F.; Thomas, A. W.; Afnan, I. R.
2000-01-01
The spectral functions and light-cone momentum distributions of protons and neutrons in 3He and 3H are given in terms of the three-nucleon wave function for realistic nucleon-nucleon interactions. To reduce computational complexity, separable expansions are employed for the nucleon-nucleon potentials. The results for the light-cone momentum distributions suggest that they are not very sensitive to the details of the two-body interaction, as long as it has reasonable short-ra...
Phenomenological study of the nucleon structure functions
International Nuclear Information System (INIS)
This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F2) and polarized (g1) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F2 and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions gp,n,d and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends
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.
Photo-production of Nucleon Resonances and Nucleon Spin Structure Function in the Resonance Region
Qing, D; Qing, Di; Schmidt, Ivan
2002-01-01
The photo-production of nucleon resonances is calculated based on a chiral constituent quark model including both relativistic corrections H{rel} and two-body exchange currents, and it is shown that these effects play an important role. We also calculate the first moment of the nucleon spin structure function g1 (x,Q^2) in the resonance region, and obtain a sign-changing point around Q^2 ~ 0.27 {GeV}^2 for the proton.
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.
International Nuclear Information System (INIS)
In the nuclear medium, there are the non-nucleonic components. The leak-out partons, which form some colour-singlet parton clusters, are the origin of the non-nucleonic components. Meanwhile, the small x partons become co-used by several nucleons because the partons' longitudinal size extends over more than one nucleon. The nucleon effective mass can be successfully used as the only free parameter to adjust the structure function ratios recently measured by NMC
Polarized structure functions of the nucleon in the resonance region
International Nuclear Information System (INIS)
Aspects of the spin structure functions of proton and neutrons at low mentum transfer Q2 and energy transfer ?, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A1p, A2p and A11n structure functions at CEBAF in a Q2 range from 0.15 to 2.0 GeV2, and a W range from threshold to 2.2 GeV are presented
Determination of nucleon structure functions from neutrino-iron scattering
International Nuclear Information System (INIS)
In the present thesis from inelastic neutrino-iron scattering the nucleon structure functions 2xF1, F2, xF3, anti q are determined. The data acquisition was performed 1983 at CERN in the 400 GeV neutrino broad-band beam with the improved CDHS detector. The statistics could be essentially raised against the last CDHS structure-function measurement. (orig./HSI)
Structure Functions of the Nucleon and their Interpretation
Cooper-sarkar, Am; Devenish, Rce; Roeck, A.
1997-01-01
The current status of measurements of the nucleon structure functions and their understanding is reviewed. The fixed target experiments E665, CCFR and NMC and the HERA experiments HI and ZEUS are discussed in some detail. The extraction of parton momentum distribution functions from global fits is described, with particular attention paid to much improved information on the gluon momentum distribution. The status of ? s measurements from deep inelastic data is revi...
The gluon contribution to polarised nucleon structure functions
International Nuclear Information System (INIS)
As with all parton distributions in quantum chromodynamics (QCD) the separation of polarised nucleon structure functions into gluon and quark contributions must be specified. We consider a definition of the gluon contribution to polarised nucleon structure functions based on exclusive processes which is explicitly gauge invariant, has no regularisation ambiguities, is insensitive to infrared singularities and can be related to other polarised scattering processes. We discuss the relationship of this gluon definition to others that have recently been used and to the estimates that have been made of the gluon contribution using current algebra and other methods. A quantitative analysis of the structure function g1(x,Q2) for polarised deep inelastic scattering is carried out, with the aim of examining the importance of the gluon contribution. Using the positivity of parton distributions the magnitude of ?g(x,Q2) is constrained by a realistic estimate of the unpolarised glue. With the appropriate choice of the hard scattering cross-section, ???g, we find that even with a maximally polarised glue (for x > 0.1), some polarised strange quark contribution is still needed by the data of the EMC. (author)
Collinear Structure Functions of the Nucleon: Status and Future
International Nuclear Information System (INIS)
While our ultimate goal is a complete three-dimensional picture of the nucleon in terms of its fundamental constituents, there are still important lessons to be learned about its ''one-dimensional'' collinear parton distribution functions (PDFs) like f1(x) and g1(x). There are rigorous proofs for factorization and universality (process independence) which make these PDFs fundamental. They also appear as limits of Generalized Parton Distributions (GPD) and as integrals of transverse momentum-dependent (TMD) parton distribution functions. Experimentally, the unpolarized structure functions F1(x,Q2), F2(x,Q2) have been studied over a huge kinematic range in both variables. Information on the polarized structure functions g1(x,Q2), g2(x,Q2) is somewhat more limited, both in kinematics and in statistical precision. In both cases, much less is known about the neutron than the proton, due to the absence of a free neutron target. Accessing these structure functions at large x (where valence quarks dominate) has been challenging due to the high luminosity and the high resolution required. Finally, much information can be extracted from studying higher twist contributions to these structure functions and the connection between the DIS limit and the region where nucleon resonance excitation dominates. In my talk, I will present an overview of recent experimental results (with special emphasis on the valence region and the transition from quark to hadronic degrees of freedom). I will also give an outlook on the next round of experiments coming online with the energy-upgraded Jefferson Lab electron beam, and future projects like the Electron Ion Collider
Nucleon spin structure functions from HERMES: The first year
International Nuclear Information System (INIS)
HERMES, HERA Measurement of Spin, is a second generation exper to study the spin structure of the nucleon by using polarized internal gas targets in the HERA 28 GeV electron storage ring. Scattered positrons and coincident hadrons are detected in an open geometry spectrometer which includes particle identification. Inclusive data with polarized 3He give the spin structure function gn1(x) and the Ellis-Jaffe integral RR? = ?01 gn1(x)dx for the neutron. The semi-inclusive spin asymmetries are a unique and sensitive probe of the flavor dependence of quark helicity distributions and properties of the quark sea. Data taken in 1995 with unpolarized hydrogen and deuterium targets provide measurements of the flavor distributions of sea and valence quarks. In a preliminary analysis, ?n1 = -0.032±0. 013stat. ± O.017syst. is obtained at Q2 = 3(GeV/c)2 for the Ellis-Jaffe integral
Convolution model for the structure functions of the nucleon
Keppler, J
1994-01-01
We start from an MIT-bag model calculation which provides information about the constituent quark distributions in the nucleon. The constituent quarks, however, are themselves considered as complex objects whose partonic substructure is resolved in deep inelastic scattering. This gives rise to structure functions of the constituent quarks which, in the unpolarized case, are fitted to data at a fixed scale employing three model parameters. Using Q^{2}--evolution equations the data are also well described at other scales. For the spin\\-dependent struc\\-ture func\\-tions g_{1}^{p,n} we additionally have to introduce polar\\-izat\\-ion functions for valence and sea quarks which are determined by exploiting the x--dependence of the available proton data only. A negatively polarized sea in the range x\\geq 0.01 is suggested. We are then capable of predicting the shape of the neutron structure function g_{1}^{n} which turns out to be in good agreement with experiment. Finally we present an estimate for the trans\\-versel...
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...
Neutrinos and nucleon structure
International Nuclear Information System (INIS)
The study of neutrino interactions in matter is yielding a wealth of information on the form factors and structure functions of the nucleon. These data allow tests of models of nucleon structure and of dynamical theories of quarks and gluons. We attempt a critical appraisal of recent facts and their impact on our theoretical understanding. (orig.)
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
Structure functions of the nucleon in a statistical model
International Nuclear Information System (INIS)
Deep inelastic scattering is considered in a statistical model of the nucleon. This incorporates certain features which are absent in the standard parton model such as quantum statistical correlations which play a role in the propagation of particles when considering Feynman diagrams containing internal lines. The inclusion of the O(?s) corrections in our numerical calculations allows a good fit to the data for x ? 0.25. The fit corresponds to values of temperature and chemical potential of approximately T = 0.067 GeV and ? = 0.133 GeV. The latter values of parameters, however, give rise, for all x, to a large value for R = ?L/?T. Even when taking into account that all measurements of R suffer from large experimental errors due to the weak dependence of the deep inelastic cross section for charged leptons on R, the size of the discrepancy remains unacceptable. This indicates a shortcoming of the statistical model in its present form to reproduce the structure function of the proton. (orig.)
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
Contribution of the spin-1 diquark to the nucleon's g1 structure function
International Nuclear Information System (INIS)
This is the final installment of a series of work that we have done in the context of the meson cloud model that investigates F2 and g1 structure functions. In our previous work on g1 structure function, we showed that having a spin-0 quark-diquark for the nucleon core along with both pseudoscalar and vector meson clouds was not sufficient to reproduce experimental observation(s) consistently. For the F2 structure function, we found that both superposition of a spin-0 diquark and a spin-1 diquark in the nucleon core along with pseudoscalar and vector meson clouds are needed to reproduce the observed F2(x) and the Gottfried sum rule (GSR) violation. Therefore, in the present work, we consider the contribution of a spin-1 diquark in the nucleon core to the g1 structure function. The calculation is performed in the light-cone frame. The dressed nucleon is assumed to be a superposition of the bare nucleon plus virtual light-cone Fock states of baryon-meson pairs. For the bare nucleon, we consider different quark-diquark configurations along with the possibility that there is no diquark inside the nucleon. The initial distributions are evolved. The final results are compared with experimental results and other theoretical predictions.
Contribution of the spin-1 diquark to the nucleon's g1 structure function
Zamani, F.
2010-07-01
This is the final installment of a series of work that we have done in the context of the meson cloud model that investigates F2 and g1 structure functions. In our previous work on g1 structure function, we showed that having a spin-0 quark-diquark for the nucleon core along with both pseudoscalar and vector meson clouds was not sufficient to reproduce experimental observation(s) consistently. For the F2 structure function, we found that both superposition of a spin-0 diquark and a spin-1 diquark in the nucleon core along with pseudoscalar and vector meson clouds are needed to reproduce the observed F2(x) and the Gottfried sum rule (GSR) violation. Therefore, in the present work, we consider the contribution of a spin-1 diquark in the nucleon core to the g1 structure function. The calculation is performed in the light-cone frame. The dressed nucleon is assumed to be a superposition of the bare nucleon plus virtual light-cone Fock states of baryon-meson pairs. For the bare nucleon, we consider different quark-diquark configurations along with the possibility that there is no diquark inside the nucleon. The initial distributions are evolved. The final results are compared with experimental results and other theoretical predictions.
Nuclear medium effects in structure functions of nucleon at moderate $Q^2$
Haider, H; Athar, M Sajjad; Singh, S K; Simo, I Ruiz
2015-01-01
Recent experiments performed on inclusive electron scattering from nuclear targets have measured the nucleon electromagnetic structure functions $F_1(x,Q^2)$, $F_2(x,Q^2)$ and $F_L(x,Q^2)$ in $^{12}C$, $^{27}Al$, $^{56}Fe$ and $^{64}Cu$ nuclei. The measurements have been done in the energy region of $1 GeV^2 < W^2 < 4 GeV^2$ and $Q^2$ region of $0.5 GeV^2 < Q^2 < 4.5 GeV^2$. We have calculated nuclear medium effects in these structure functions arising due to the Fermi motion, binding energy, nucleon correlations, mesonic contributions from pion and rho mesons and shadowing effects. The calculations are performed in a local density approximation using relativistic nucleon spectral function which include nucleon correlations. The numerical results are compared with the recent experimental data from JLab and also with some earlier experiments.
Charged current neutrino and antineutrino interactions and nucleon structure functions
International Nuclear Information System (INIS)
Final results are presented for studies, carried out by the HPWFRO-E310 group at Fermi National Accelerator Laboratory, of inclusive charged current neutrino and antineutrino interactions. The data sample consists of 21578 neutrino and 7358 antineutrino events within the fiducial regions of the calorimeter targets in the energy interval 20 2 >/E with increasing energy. R = (integral F2(x)dx/integral 2xF1(x)dx)-1 was determined in the energy interval 20 2 and xF3 for an isoscalar target are calculated and studied as functions of x at fixed energy and as functions of Q2 at fixed x. Both F2 and xF3 increase at small x and decrease at large x as either the energy of Q2 increases. The changes in the structure functions, hence the distributions in the scaling variables x and y, are attributed to charm production from strange quarks in the sea and the inherent Q2 dependence of the structure functions as predicted by quantum chromodynamics (QCD). Tables o by quantum chromodynamics (QCD). Tables of the structure functions are provided, in addition, momentum fraction distributions of the antiquarks are calculated by several methods and presented in various energy intervals. A comparison is made between the antiquark distributions and x anti s/sub p/(x) as derived from the antineutrino induced dimuon data from the experiment. Systematic effects are discussed throughout and detailed comparisons are made with data from other experiments
The Spin-Dependent Structure Functions of Nuclei in the Meson-Nucleon Theory
Kaptari, L. P.; Umnikov, A. Yu; Atti, C. Ciofi Degli; Scopetta, S.; Kazakov, K. Yu
1994-01-01
A theoretical approach to the investigation of spin-dependent structure functions in deep inelastic scattering of polarized leptons off polarized nuclei, based on the effective meson-nucleon theory and operator product expansion method, is proposed and applied to deuteron and $^3He$. The explicit forms of the moments of the deuteron and $^3He$ spin-dependent structure functions are found and numerical estimates of the influence of nuclear structure effects are presented.
Polarized and unpolarized nucleon structure functions from lattice QCD
International Nuclear Information System (INIS)
We report on a high statistics quenched lattice QCD calculation of the deep-inelastic structure functions F1, F2, g1 and g2 of the proton and neutron. The theoretical basis for the calculation is the operator product expansion. We consider the moments of the leading twist operators up to spin four. Using Wilson fermions the calculation is done for three values of K, and we perform the extrapolation to the chiral limit. The renormalization constants, which lead us from lattice to continuum operators, are calculated in perturbation theory to one loop order. (orig.)
Deuteron spin-dependent structure function within an effective meson-nucleon theory
International Nuclear Information System (INIS)
A consistent theoretical approach is suggested for the description of deep inelastic scattering of polarized leptons off polarized deuterons within the operator product expansion method and an effective meson-nucleon theory. The approach describes fairly well recent deuteron experimental data on the spin structure function. 18 refs.; 2 figs
Polarized deeply inelastic scattering (DIS) structure functions for nucleons and nuclei
International Nuclear Information System (INIS)
We extract parton distribution functions (PDFs) and structure functions from recent experimental data of polarized lepton-deeply inelastic scattering (DIS) on nucleons at next-to-leading order (NLO) quantum chromodynamics. We apply the Jacobi polynomial method to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution as this is numerically efficient. Having determined the polarized proton and neutron spin structure, we extend this analysis to describe 3He and 3H polarized structure functions, as well as various sum rules. We compare our results with other analyses from the literature.
The structure functions g1 and g2 of the nucleon in the meson cloud model
International Nuclear Information System (INIS)
We calculate the spin dependent structure functions g 1(x) and g 2(x) of the nucleon in the meson cloud model of nucleon structure. The contributions from kinematic terms which mix transverse and longitudinal spin components are included. The structure functions of the barehadrons are calculated by using the MIT bag model and the method of the Adelaide group. The contributions from polarized gluon distributions are taken into account in a phenomenological way. The calculations agree with the experimental measurements for g 1(x) and g 2(x) of the proton and the neutron in a large range of x (0.01 < x < 0.6). PACS numbers: 14.20.Dh, 13.88 + e, 11.30 Hv, 12.39.Ba, 13.60.Hb
Moments of nuclear and nucleon structure functions at low Q2 and the momentum sum rule
International Nuclear Information System (INIS)
New nuclear structure function data from Jefferson Lab covering the higher x and lower Q2 regime make it possible to extract the higher order F2 moments for iron and deuterium at low four-momentum transfer squared Q2. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the non-singlet nucleon moment with Lattice QCD results
Moments of nuclear and nucleon structure functions at low Q2 and the momentum sum rule
International Nuclear Information System (INIS)
New nuclear structure function data from Jefferson Lab covering the higher-x and lower-Q2 regime make it possible to extract the higher-order F2 moments for iron and deuterium at low four-momentum transfer squared Q2. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the nonsinglet nucleon moment with lattice QCD results
Moments of nuclear and nucleon structure functions at low Q^2 and the momentum sum rule
Niculescu, I.; Arrington, J.; Ent, R.; Keppel, C. E.
2005-01-01
New nuclear structure function data from Jefferson Lab covering the higher x and lower Q^2 regime make it possible to extract the higher order F_2 moments for iron and deuterium at low four-momentum transfer squared Q^2. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the non-singlet nucleon moment with Lattice QCD results.
Nucleon structure functions from ?mu-Fe scattering at the Tevatron
International Nuclear Information System (INIS)
We present preliminary results for nucleon structure functions measured in high energy neutrino interactions. Included are new results for the Gross-Llewellyn Smith Sum Rule, ?x/1xF3dx = 2.66 ± .03(stat)±.08(syst), the ratio of cross-sections, ?bar?/?? = .511 ± .002(stat) ± .005(syst), and an analysis of the Q2 evolution of xF3. 16 refs., 5 figs
Spin structure functions of the nucleon at low Q2 and ?
International Nuclear Information System (INIS)
Phenomenological approaches to describe the spin structure functions an spin sum rules for proton and neutrons at low momentum transfer Q2 and energy transfer ?, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A1p, A2p and N1n structure functions at CEBAF in a Q2 range from 0.15 to 2.0 GeV2, and a W range from threshold to 2.2 GeV are presented
Method on nucleon structure function reconstruction from the deep inelastic scattering data
International Nuclear Information System (INIS)
To reconstruct the nucleon structure function from the directly measured experimental cross section of the deep inelastic scattering of muons, Fredholm integral equation of the first kind is considered in its two-dimensional version. The free term of the equation (experimental cross section) and the kernel have statistical errors. The quation's solution (structure function) is found by the statistical regularization method, the regularization parameters being chosen on the basis of the maximum likelihood in a laminar enseble of smooth functions. Generalization of the method is suggested, where the kernel errors are taken into account. The use of this a priori information as growth of the structure function in one of the directions is shown
Atti, Claudio Ciofi Degli; West, Geoffrey B.
1997-01-01
Some systematic general features of y-scaling structure functions, which are essentially independent of detailed dynamics, are pointed out. Their physical interpretation in terms of general characteristics, such as a mean field description and nucleon-nucleon correlations, is given and their relationship to the momentum distributions illustrated. A new scaling variable is proposed which allows a direct expression of the scaling function in term of an integral over the momemt...
Watanabe, Akira; Suzuki, Katsuhiko
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 struc...
Fiore, R; Kotikov, A V; Paccanoni, F; Papa, A; Predazzi, Enrico
2004-01-01
In this paper we present an analytic result for the evolution in $Q^2$ of the structure functions for the neutrino-nucleon interaction, valid at twist-2 in the region of small values of the Bjorken $x$ variable and for soft non-perturbative input. In the special case of flat initial conditions, we include in the calculation also the contribution of the twist-4 gluon recombination corrections, whose effect in the evolution is explicitly determined. Finally, we estimate the resulting charged-current neutrino-nucleon total cross section and discuss its behavior at ultra-high energies.
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.
Fiore, R.; Jenkovszky, L. L; A.V. Kotikov; Paccanoni, F.; A. Papa; Predazzi, E.
2004-01-01
In this paper we present an analytic result for the evolution in $Q^2$ of the structure functions for the neutrino-nucleon interaction, valid at twist-2 in the region of small values of the Bjorken $x$ variable and for soft non-perturbative input. In the special case of flat initial conditions, we include in the calculation also the contribution of the twist-4 gluon recombination corrections, whose effect in the evolution is explicitly determined. Finally, we estimate the re...
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
International Nuclear Information System (INIS)
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.
Gerasimov-Drell-Hearn sum rule and behaviour of nucleon polarized structure function at small Q2
International Nuclear Information System (INIS)
Using Gerasimov-Drell-Hearn sum rule it is shown that neutron polarized structure function achieves the asymptotic value at Q2=2 GeV2. For proton polarized structure function it is shown that starting from 1.5 GeV2 its deviation from the asymptotic value does not exceed 15-20 %. The integrals over nucleon polarized structure functions are obtained in the interval of x=0,45 + 1 on the basis of available data in the resonance energy region at Q22. It appears that at Q2 =2 + 3Gev2 these integrals have scaling behaviour, and their values agree with the extrapolations to the region of large x made in experimental works
International Nuclear Information System (INIS)
Inclusive neutrino and antineutrino charged current interactions were studied in the CHARM detector exposed to neutrino and antineutrino Wide Band Beams of the CERN 400 GeV SPS. The x and Q2 dependence of the structure functions F2 and xF3 and of the antiquark momentum distribution q were determined. The data have been interpreted in terms of QCD theory using the Furmanski-Petronzio method. In this way we have determined #betta#sub(LO)=[190+70sub(-40)(stat)+-70 (syst.)] MeV and the structure functions of quarks and gluons without specific assumptions on their analytic dependence. The results agree with previous experiments which relied on model assumptions in the analysis. We conclude that the model independent simultaneous analysis of the xF3, F2, anti q structure functions gives a more reliable determination of the gluon distribution in the nucleon. (orig.)
Probing nuclear structure with nucleons
International Nuclear Information System (INIS)
The goal of this lecture is to show how nucleon scattering can be used to probe the structure of target nuclei, and how nucleon scattering observables can be interpreted in terms of nuclear structure using microscopic optical potentials. After a brief overview of the specificities of nucleon-nucleus scattering, and a quick reminder on scattering theory, the main part of this lecture is devoted to the construction of optical potentials in which the target nuclei structure information is folded with an effective interaction. Several examples of such microscopic optical model potentials are given. (author)
Khorramian, Ali N; Monfared, S Taheri; Arbabifar, F; Olness, F I
2010-01-01
We extract parton distribution functions (PDFs) and structure functions from recent experimental data of polarized lepton-DIS on nuclei at next-to-leading order (NLO) Quantum Chromodynamics. We apply the Jacobi polynomial method to the DGLAP evolution as this is numerically efficient. Having determined the polarized proton and neutron spin structure, we extend this analysis to describe 3He and 3H polarized structure functions, as well as various sum rules. We compare our results with other analyses from the literature.
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
From Nuclear Structure to Nucleon Structure
Liu, Keh-Fei
2014-01-01
Similarities between nuclear structure study with many-body theory approach and nucleon structure calculations with lattice QCD are pointed out. We will give an example of how to obtain the connected sea partons from a combination of the experimental data, a global fit of parton distribution functions and a lattice calculation. We also present a complete calculation of the quark and glue decomposition of the proton momentum and angular momentum in the quenched approximation. It is found that the quark orbital angular momentum constitutes about 50% of the proton spin.
From nuclear structure to nucleon structure
Liu, Keh-Fei
2014-08-01
Similarities between nuclear structure study with many-body theory approach and nucleon structure calculations with lattice QCD are pointed out. We will give an example of how to obtain the connected sea partons from a combination of the experimental data, a global fit of parton distribution functions and a lattice calculation. We also present a complete calculation of the quark and glue decomposition of the proton momentum and angular momentum in the quenched approximation. It is found that the quark orbital angular momentum constitutes about 50% of the proton spin.
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...
Nocera, E. R.
2015-03-01
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 ? 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.
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.
Nucleon-nucleon momentum correlation function for light nuclei
Ma, Y. G.; Cai, X. Z.(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800, Shanghai, China); Chen, J.G.; Fang, D. Q.; Guo, W; Liu, G. H.; Ma, C. W.; Ma, E. J.; Shen, W.Q.(Shanghai Institute of Applied Physics, Shanghai, 201800, China); Shi, Y; Su, Q. M.; Tian, W. D.(Shanghai Institute of Applied Physics (Chinese Academy of Sciences), 201800, Shanghai, China); Wang, H. W.(Shanghai Institute of Applied Physics (Chinese Academy of Sciences), 201800, Shanghai, China); Wang, K.; Wei, Y. B.
2006-01-01
Nucleon-nucleon momentum correlation function have been presented for nuclear reactions with neutron-rich or proton-rich projectiles using a nuclear transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model. The relationship between the binding energy of projectiles and the strength of proton-neutron correlation function at small relative momentum has been explored, while proton-proton correlation function shows its sensitivity to the proton density distrib...
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
Nucleon structure from stochastic estimators
International Nuclear Information System (INIS)
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 Nf=2 for the nucleon axial coupling gA and iso-vector quark momentum fraction u-d from various collaborations and compare them to the experimental values. The tension between them is attributed to excited state contributions (ESCs). We furthermore study the impact of ESCs in moments of GPDs through a model fit. This model also deals with the effects of the choice of parameters used in the computation, like the source-sink separation tsink. We demonstrate that the choice of tsink by the Regensburg group in previous studies was reasonable and cannot account for discrepancies with the experiment. To reduce the excited state contributions in two-point functions, and consequently three-point functions, we suggest a non-Gaussian quark smearing. This is a linear combination of two Gaussian smearings with one free parameter, which can be tuned to an optimal choice with a fit.
Nucleon Spin Structure And Electromagnetic Excitation Of Nucleon Resonances
Mathur, N
2000-01-01
Quantum Chromodynamics (QCD) is the theoretical key to study the structure of the nucleon. However, it is difficult to use, particularly in the non-perturbative domain. This work uses electromagnetic interactions to gain new theoretical insights into the non-perturbative chromodynamic structure of the nucleon. This is done in two ways. The first method adopted is the Lattice Gauge Theory to study the spin structure of the nucleon and try to answer the question, “Where does the nucleon spin come from ?” To date, theoretically, we do not have a comprehensive understanding about the nucleon spin structure. Experimental findings reveal that quark spin contributes only a small fraction to the proton spin. However, there are no data which can conclusively tell us about the contribution of gluons and the orbital angular momentum of quarks. Through lattice calculations, we have studied the total angular momentum contributions from quarks, thereby deducing the quark orbital angular momentum, and th...
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
Experimental results on polarized structure functions in deep inelastic lepton-nucleon scattering
International Nuclear Information System (INIS)
A summary is given of experimental results on spin structure functions of the proton g1p(x,Q2), deuteron g1d(x,Q2), and neutron g1n(x,Q2) as measured in deep inelastic scattering of polarized leptons from a polarized target. All results are consistent with the Bjorken sum rule predictions at the Q2 of each experiment. The data do not support the Ellis-Jaffe sum rule prediction for the proton which implies that the hencity carried by the strange quark may be nonzero and that the net quark helicity is smaller than expected from simple quark models
International Nuclear Information System (INIS)
We have studied the nuclear effects on high energy antineutrino charged current interactions by comparing the data which were taken in the Bubble Chamber BEBC filled with Neon and Deuterium. On the one hand, the study of nuclear reinteractions gave us the possibility to estimate the formation time of hadrons. On the other hand, the comparison of structure functions does not show any significant difference between Neon and Deuterium. Though this result does not contradict the effects observed with charged leptons by the EMC and SLAC experiments, it is strongly incompatible with certain theoretical interpretations which implied a stronger effect in antineutrino interactions
Finite-temperature quantum field theory and structure functions of the nucleon
International Nuclear Information System (INIS)
The deep inelastic scattering of leptons off a proton in the statistical model is considered. The interior of the nucleon is viewed as a thermalized assembly of up and down quarks and gluons. This enables the incorporation of features which are absent in the parton model. These include the presence of identical quarks and gluons in initial and final states and of quantum statistical correlations which have a role to play in the propagation of particles when considering Feynman diagrams containing internal lines in next-to-leading-order calculations. These features are incorporated through the use of Fermi-Dirac and Bose-Einstein distributions for quarks and gluons, respectively. Stimulated emission factors for final-state gluons and Pauli-blocking factors for final-state quarks are incorporated. The propagation of particles through a many-body medium is taken into account by using thermal Feynman rules for propagators and vertices. The statistical model could also be seen as an attempt to describe the interior of the nucleon at a more fundamental level than that attained through the use of arbitrary parton distributions containing many parameters in the parton model. 79 refs., 46 figs., 8 tabs
Measurements of the nucleon structure function in the range 0.00222 in deuterium, carbon and calcium
International Nuclear Information System (INIS)
Small angle scattering of 280 GeV positive muons by deuterium, carbon and calcium has been measured at scattering angles down to 2 mrad. The nucleon structure function F2 extracted from deuterium does not show a significant x dependence in the measured range of Q2 and its Q2 dependence is linear in log Q2. For calcium, a depletion of F2 is observed at low x by 30% as compared with the values at x=0.1 where F2(Ca) and F2(D) are not significantly different. This depletion is attributed to shadowing. The carbon structure function exhibits a similar, but less pronounced, x dependence. Such behaviour is observed to be independent of Q2. The data are consistent with those obtained from other charged lepton experiments both a similar and higher values of x and Q2 and considerably extend the range of the measurements down to the low values of x to be measured in forthcoming experiments at HERA. (orig.)
Nucleon structure from stochastic estimators
Bali, Gunnar S; Gläßle, Benjamin; Göckeler, Meinulf; Najjar, Johannes; Rödl, Rudolf; Schäfer, Andreas; Sternbeck, André; Söldner, Wolfgang
2013-01-01
Using stochastic estimators for connected meson and baryon three-point functions has successfully been tried in the past years. Compared to the standard sequential source method we trade the freedom to compute the current-to-sink propagator independently of the hadron sink for additional stochastic noise in our observables. In the case of the nucleon we can use this freedom to compute many different sink-momentum/polarization combinations, which grants access to more virtualities. We will present preliminary results on the scalar, electro-magnetic and axial form factors of the nucleon in $N_f=2+1$ lattice QCD and contrast the performance of the stochastic method to the sequential source method. We find the stochastic method to be competitive in terms of errors at fixed cost.
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
Nuclear Structure based on Correlated Realistic Nucleon-Nucleon Potentials
Roth, R.; Neff, T.; Hergert, H.; Feldmeier, H.
2004-01-01
We present a novel scheme for nuclear structure calculations based on realistic nucleon-nucleon potentials. The essential ingredient is the explicit treatment of the dominant interaction-induced correlations by means of the Unitary Correlation Operator Method (UCOM). Short-range central and tensor correlations are imprinted into simple, uncorrelated many-body states through a state-independent unitary transformation. Applying the unitary transformation to the realistic Hamil...
International Nuclear Information System (INIS)
The authors present the analytic leading-twist three-loop pertur-bative QCD correction to the moment ?01dxFLp-n(x,Q2) of the non-singlet longitudinal structure function FL of the deep inelastic electron-nucleon scattering. It provides quantitative information on uncertainties of pQCD predictions for D(x,Q2) ?l/?/T. (author). 24 refs.; 2 figs
New Results on Nucleon Spin Structure
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen
2005-09-10
Recent precision spin structure data from Jefferson Lab have significantly advanced our knowledge of nucleon structure in the valence quark (high-x) region and improved our understanding of higher-twist effects, spin sum rules and quark-hadron duality. First, results of a precision measurement of the neutron spin asymmetry, A{sub 1}{sup n}, in the high-x region are discussed. The new data shows clearly, for the first time, that A{sub 1}{sup n} becomes positive at high x. They provide crucial input for the global fits to world data to extract polarized parton distribution functions. Preliminary results on A{sub 1}{sup p} and A{sub 1}{sup d} in the high-x region have also become available. The up and down quark spin distributions in the nucleon were extracted. The results for {Delta}d/d disagree with the leading-order pQCD prediction assuming hadron helicity conservation. Then, results of a precision measurement of the g{sub 2}{sup n} structure function to study higher-twist effects are presented. The data show a clear deviation from the lead-twist contribution, indicating a significant higher-twist (twist-3 or higher) effect. The second moment of the spin structure functions and the twist-3 matrix element d{sub 2}{sup n} results were extracted at a high Q{sup 2} of 5 GeV{sup 2} from the measured A{sub 2}{sup n} in the high-x region in combination with existing world data and compared with a Lattice QCD calculation. Results for d{sub 2}{sup n} at low-to-intermediate Q{sup 2} from 0.1 to 0.9 GeV{sup 2} were also extracted from the JLab data. In the same Q{sup 2} range, the Q{sup 2} dependence of the moments of the nucleon spin structure functions was measured, providing a unique bridge linking the quark-gluon picture of the nucleon and the coherent hadronic picture. Sum rules and generalized forward spin polarizabilities were extracted and compared with Chiral Perturbation Theory calculations and phenomenological models. Finally, preliminary results on the resonance spin structure functions in the Q{sup 2} range from 1 to 4 GeV{sup 2} were presented, which, in combination with DIS data, will enable a detailed study of the quark-hadron duality in spin structure functions.
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...
Flavor Structure of the Nucleon Sea
Chang, Wen-Chen
2014-01-01
We review the current status and future prospects on the subject of flavor structure of the nucleon sea. The flavor structure of the nucleon sea provides unique information on the non-perturbative aspects of strong interactions allowing stringent tests of various models on the partonic structures of the nucleons as well as lattice QCD calculations. The scope of this review covers the unpolarized, polarized, and the transverse-momentum dependent sea-quark distributions of the nucleons. While the main focus of this review is on the physics motivation and recent progress on the subject of nucleon sea, we also discuss future prospects of addressing some outstanding issues on the flavor structure of the nucleon sea.
Flavor structure of the nucleon sea
Chang, Wen-Chen; Peng, Jen-Chieh
2014-11-01
We review the current status and future prospects on the subject of flavor structure of the nucleon sea. The flavor structure of the nucleon sea provides unique information on the non-perturbative aspects of strong interactions allowing stringent tests of various models on the partonic structures of the nucleons as well as lattice QCD calculations. The scope of this review covers the unpolarized, polarized, and the transverse-momentum dependent sea-quark distributions of the nucleons. While the main focus of this review is on the physics motivation and recent progress on the subject of the nucleon sea, we also discuss future prospects of addressing some outstanding issues on the flavor structure of the nucleon sea.
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
The Spin Structure of the Nucleon
Vetterli, Martin C
1999-01-01
This paper gives a pedagogical introduction to our knowledge of the spin structure of the nucleon. In particular, polarised deep inelastic lepton scattering is presented as a tool to study how the nucleon's constituents combine to generate its spin. The importance of semi-inclusive measurements is discussed and a window on future experiments in the field is given.
International Nuclear Information System (INIS)
Scaling violations in the nucleon structure function F2(x, Q2) measured with high statistics in deep inelastic scattering of muons on a carbon target are compared to predictions of perturbative QCD. Excellent agreement is observed with numerical solutions of the Altarelli-Parisi evolution equations over entire x and Q2 range of the data. In a next-to-leading order nonsinglet approximation, the QCD mass scale parameter ?MS is determined to be 230 ± 20 (stat.) ± 60 (syst.) MeV. A singlet fit to the data favours a soft gluon distribution
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.
Nuclear Structure based on Correlated Realistic Nucleon-Nucleon Potentials
Roth, R; Hergert, H; Feldmeier, H
2004-01-01
We present a novel scheme for nuclear structure calculations based on realistic nucleon-nucleon potentials. The essential ingredient is the explicit treatment of the dominant interaction-induced correlations by means of the Unitary Correlation Operator Method (UCOM). Short-range central and tensor correlations are imprinted into simple, uncorrelated many-body states through a state-independent unitary transformation. Applying the unitary transformation to the realistic Hamiltonian leads to a correlated, low-momentum interaction, well suited for all kinds of many-body models, e.g., Hartree-Fock or shell-model. We employ the correlated interaction, supplemented by a phenomenological correction to account for genuine three-body forces, in the framework of variational calculations with antisymmetrised Gaussian trial states (Fermionic Molecular Dynamics). Ground state properties of nuclei up to mass numbers A<~60 are discussed. Binding energies, charge radii, and charge distributions are in good agreement with ...
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
The nucleon wave function at the origin
Gruber, Michael
2010-01-01
We calculate the next-to-leading order perturbative corrections to the SVZ sum rules for the coupling f_N, the nucleon leading twist wave function at the origin. The results are compared to the established Ioffe sum rules and also to lattice QCD simulations.
The nucleon wave function at the origin
International Nuclear Information System (INIS)
We calculate the next-to-leading order perturbative corrections to the SVZ sum rules for the coupling fN, the nucleon leading twist wave function at the origin. The results are compared to the established Ioffe sum rules and also to lattice QCD simulations.
Liang, Y; Ahmidouch, A; Armstrong, C S; Arrington, J; Asaturyan, R; Avery, S; Baker, O K; Beck, D H; Blok, H P; Bochna, C W; Böglin, W; Bosted, P; Bouwhuis, M; Breuer, H; Brown, D S; Brüll, A; Carlini, R D; Cha, J; Chant, N S; Cochran, A; Cole, L; Danagulyan, S; Day, D B; Dunne, J; Dutta, D; Ent, R; Fenker, H C; Fox, B; Gan, L; Gao, H; Garrow, K; Gaskell, D; Gasparian, A; Geesaman, D F; Gilman, R; Gueye, P L J; Harvey, M; Holt, R J; Jiang, X; Jones, M; Keppel, C E; Kinney, E; Lorenzon, W; Lung, A; Mack, D J; Markowitz, P; Martin, J W; McIlhany, K; McKee, D; Meekins, D; Miller, M A; Milner, R G; Mitchell, J H; Mkrtchyan, H G; Müller, B A; Nathan, A; Niculescu, G; Niculescu, I; O'Neill, T G; Papavassiliou, V; Pate, S F; Piercey, R B; Potterveld, D; Ransome, R D; Reinhold, J; Rollinde, E; Rondon, Oscar A; Roos, P; Sarty, A J; Sawafta, R; Schulte, E C; Segbefia, E; Smith, C; Stepanyan, S; Strauch, S; Tadevosyan, V; Tang, L; Tieulent, R; Tvaskis, V; Uzzle, A; Vulcan, W F; Wood, S A; Xiong, F; Yuan, L; Zeier, M; Zihlmann, B; Ziskin, V
2004-01-01
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^2 < 5.5 GeV^2. The data have been used to accurately perform over 170 Rosenbluth-type longitudinal / transverse separations. The precision R = sigma_L / sigma_T data are presented here, along with the first separate values of the inelastic structure functions F_1 and F_L in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q^2 = 1 GeV^2 in the separated structure functions independently.
Modelling the nucleon wave function from soft and hard processes
International Nuclear Information System (INIS)
Since current light-cone wave functions for the nucleon are inconsistent with the data on the nucleon's Dirac form factor, a new wave function is suggested respecting theoretical ideas on its parameterization and satisfying constraints from experimental data. (author)
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 Qable 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)
Chiral symmetry and nucleon structure
Energy Technology Data Exchange (ETDEWEB)
Holstein, B.R. (Massachusetts Univ., Amherst, MA (United States). Dept. of Physics and Astromony Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory)
1992-01-01
Recently it has been realized that significant tests of the validity of QCD are available in low energy experiments (E < 500 MeV) by exploiting the property of (broken) chiral symmetry. This technique has been highly developed in The Goldstone boson sector by the work of Gasser and Leutwyler. Application to the nucleon system is much more difficult and is now being carefully developed.
Chiral symmetry and nucleon structure
International Nuclear Information System (INIS)
Recently it has been realized that significant tests of the validity of QCD are available in low energy experiments (E < 500 MeV) by exploiting the property of (broken) chiral symmetry. This technique has been highly developed in The Goldstone boson sector by the work of Gasser and Leutwyler. Application to the nucleon system is much more difficult and is now being carefully developed
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
International Nuclear Information System (INIS)
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 Poincaré-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 re expressed 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. (author)
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.
Spin Structure of the Nucleon - Status and Recent Results
Kuhn, S E; Leader, E
2008-01-01
After the initial discovery of the so-called "spin crisis in the parton model" in the 1980s, a large set of polarization data in deep inelastic lepton-nucleon scattering was collected at labs like SLAC, DESY and CERN. More recently, new high precision data at large x and in the resonance region have come from experiments at Jefferson Lab. These data, in combination with the earlier ones, allow us to study in detail the polarized parton densities, the Q^2 dependence of various moments of spin structure functions, the duality between deep inelastic and resonance data, and the nucleon structure in the valence quark region. Together with complementary data from HERMES, RHIC and COMPASS, we can put new limits on the flavor decomposition and the gluon contribution to the nucleon spin. In this report, we provide an overview of our present knowledge of the nucleon spin structure and give an outlook on future experiments. We focus in particular on the spin structure functions g_1 and g_2 of the nucleon and their momen...
Nuclear structure based on correlated realistic nucleon-nucleon potentials
International Nuclear Information System (INIS)
We present a novel scheme for nuclear structure calculations based on realistic nucleon-nucleon potentials. The essential ingredient is the explicit treatment of the dominant interaction-induced correlations by means of the unitary correlation operator method (UCOM). Short-range central and tensor correlations are imprinted into simple, uncorrelated many-body states through a state-independent unitary transformation. Applying the unitary transformation to the realistic Hamiltonian leads to a correlated, low-momentum interaction, which is well suited for all kinds of many-body models, e.g., Hartree-Fock or shell-model. We employ the correlated interaction, supplemented by a phenomenological correction, in the framework of variational calculations with antisymmetrised Gaussian trial states (fermionic molecular dynamics). Ground state properties of nuclei up to mass numbers A-bar 60 are discussed. Binding energies, charge radii, and charge distributions are in good agreement with experimental data. We perform angular momentum projections of the intrinsically deformed variational states (projection after variation) to extract rotational spectra. Finally, we discuss perspectives for variation after projection and multi-configuration calculations
International Nuclear Information System (INIS)
We present results from a high statistics study of the nucleon structure function F2(x,Q2) measured in deep inelastic scattering of muons on carbon in the kinematic range 0.25 ? x ? 0.80 and Q2 ? 25 GeV2. The analysis is based on 1.5x106 reconstructed events recorded at beam energies of 120, 200 and 280 GeV. R = ?L/?T is found to be independent of x in the range 0.25 ? x ? 0.7 and 40 GeV2 ? Q2 ? 200 GeV2 with a mean value R = 0.015±0.013(stat)±0.026(syst.). (orig.)
International Nuclear Information System (INIS)
Deep inelastic scattering cross sections have been measured with the CERN SPS muon beam at incident energies of 120 and 200 Gev. Approximately 100000 events at each energy are used to obtain the structure function F2(x, Q2) in the kinetic region 0.3222. It is seen from these data that Q2 dependence of the structure function is very slight for Q2>25 GeV2. A more detailed description of F2(x, Q2) can be obtained in the framework of the QCD. On the basis of the obtained data the ? parameter characterizing the strength of strong interactions has been determined by different methods and occurred to be about 100 MeV. This value is lower than what has been found elsewhere
Bollini, D; Benvenuti, Alberto C; Bozzo, M; Brun, R; Cvach, J; Dobrowolski, T; Fadeev, N G; Feltesse, J; Frabetti, P L; Gennow, H; Golutvin, I A; Goossens, M; Heiman, G; Jamnik, D; Kiryushin, Yu T; Kisselev, V S; Klein, M; Kopp, R; Krivokhizhin, V G; Kukhtin, V V; Maillard, J; Malasoma, J M; Meyer-Berkhout, U; Milsztajn, A; Monari, L; Navach, F; Navarria, Francesco Luigi; Nowak, Wolf-Dieter; Piemontese, L; Pilcher, J E; Renardy, J F; Sacquin, Yu; Savin, I A; Schinzel, D; Smadja, G; Smirnov, G I; Staude, A; Teichert, K M; Tirler, R; Verrecchia, P; Vesztergombi, G; Virchaux, M; Volodko, A G; Voss, R; Zácek, J; Zupancic, Crtomir
1981-01-01
Deep inelastic scattering cross sections have been measured with the CERN SPS muon beam at incident energies of 120 and 200 GeV. Approximately 10000 events at each energy used to obtain the structure function F/sub 2/(x, Q/sup 2/) in the kinematic region 0.3
Nucleon spin structure studies at COMPASS
Marchand, Claude
2006-01-01
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 $^{6}$LiD 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 $\\Delta G/G$, accessed via asymmetries involving photon-gluon fusion mechanism (PGF). Both open charm production (detecting $D^{0}$’s), as well as production of hight $p_{T}$ hadron pairs are used to tag PGF. Preliminary results for $\\Delta G/G$ based on the analysis of 2002 and 2003 data are shown. In addition, improved measurement of the deuteron structure function $g^{d}_{1}$ at small $x$, as well as studies of transverse distribution functions in the deuteron by measuring Collins and Sivers azimuthal...
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
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.
Probing the nucleon structure with SIDIS at Jefferson Lab
International Nuclear Information System (INIS)
In recent years, measurements of azimuthal moments of polarized hadronic cross sections in hard processes have emerged as a powerful tool to probe nucleon structure. Many experiments worldwide are currently trying to pin down various effects related to nucleon structure through Semi-Inclusive Deep-Inelastic Scattering (SIDIS). Azimuthal distributions of final-state particles in semi-inclusive deep inelastic scattering, in particular, are sensitive to the orbital motion of quarks and play an important role in the study of Transverse Momentum Dependent parton distribution functions (TMDs) of quarks in the nucleon. The CLAS spectrometer, installed in Hall-B at Jefferson Lab, has collected semi-inclusive data using the CEBAF 6 GeV polarized electron beam on polarized solid NH3 and ND3 targets. An overview of these measurements is presented
International Nuclear Information System (INIS)
Some interesting features of the experimental data on deep inelastic scattering of muons from a liquid hydrogen target are discussed. The proton structure function F2(x,q2) (where x=q2/2m(E-Esup(')), E and Esup(') stand for initial and final muon energy, respectively) has proved to fall at large x and rise at small x with increasing q2. To make extrapolations into q2 regions not covered by the data available, the integral 1?0F2(x,q2)dx has been calculated. The integral has occureed to be constant with q2. The set of data is hoped to be explained in terms of renormalizable field theories
Nucleon spin structure at very high-x
Roberts, Craig D; Schmidt, Sebastian M
2013-01-01
Dyson-Schwinger equation treatments of the strong interaction show that the presence and importance of nonpointlike diquark correlations within the nucleon are a natural consequence of dynamical chiral symmetry breaking. Using this foundation, we deduce a collection of simple formulae, expressed in terms of diquark appearance and mixing probabilities, from which one may compute ratios of longitudinal-spin-dependent u- and d-quark parton distribution functions on the domain x =1. A comparison with predictions from other approaches plus a consideration of extant and planned experiments shows that the measurement of nucleon longitudinal spin asymmetries on x =1 can add considerably to our capacity for discriminating between contemporary pictures of nucleon structure.
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.
Structure and spin of the nucleon
Avakian, H.
2014-03-01
Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Nucleon structure and high energy interactions
Selyugin, O V
2015-01-01
On the basis of the representation of the generalized structure of nucleons a new model of the hadron interaction at high energies is presented. The new t-dependence of the generalized parton distributions (GPDs) is obtained from the comparative analysis of different sets of the parton distribution functions (PDFs), based on the description of the whole sets of experimental data of electromagnetic form factors of the proton and neutron. Taking into account the different moments of GPDs of the hadron the quantitative descriptions of all existing experimental data of the proton-proton and proton-antiproton elastic scattering from $\\sqrt{s} = 9.8$ GeV to $8$ TeV, including the Coulomb range and large momentum transfers up to $-t=15$ GeV$^2$, are obtained with a few free fitting high energy parameters. The real part of the hadronic elastic scattering amplitude is determined only through complex $s$ satisfying the dispersion relations. The negligible contributions of the hard Pomeron and the presence of the non-sm...
Nucleon electromagnetic structure: past, present, and future
International Nuclear Information System (INIS)
We present the experimental status of electromagnetic hadron form factors. New and surprising results, based on polarization measurements, have been recently obtained for the electric proton and neutron factors. In particular, the electric and magnetic distributions inside the proton appear not to be the same, in disagreement with results extracted from the unpolarized cross-section, using the Rosenbluth separation. The new findings have given rise to a large number of papers and different speculators, as they question directly the models of nucleon structure and reaction mechanisms itself (based on 1 ?-exchange), with a possible revision of the calculation of radiative corrections, two-photon contribution, etc. New data in time-like region are also available, through annihilation reactions. A large interest in this field arises, due also to the possibility of new measurements in polarized electron nucleon elastic scattering at JLAB, and also in the time-like region, at Frascati and at the future FAIR international facility
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.
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
Recent Results on Structure Functions
International Nuclear Information System (INIS)
This presentation deals with the Unpolarized nucleon structure, the Longitudinal (transverse) spin structure and the 3-dimensional Structure of nucleon (Transverse momentum dependent parton distributions (TMDs) and Generalized parton distributions (GPDs)). In summary, major progress has been made in unpolarized and polarized structure functions. The frontiers in nucleon structure go beyond colinear, 1-D picture: three-dimensional imaging of the nucleon through GPDs, revealing hidden aspects of its internal dynamics; TMDs have a direct link with orbital motion (orbital angular momentum). They also describe the transverse motion: spin-orbit correlations, multi-parton correlations, dynamics of confinement and QCD. JLab 12-GeV upgrade and COMPASS II experiments will provide excellent opportunities to map out the 3-dimensional structure of the nucleon
Internal Spin Structure of the Nucleon in Polarized Deep Inelastic Muon-Nucleon Scattering
International Nuclear Information System (INIS)
We present the study of the internal spin structure of the nucleon in spin-dependent deep inelastic scattering of muons on nucleons. The data were taken by the NA47 experiment of the Spin Muon Collaboration (SMC) on the high energy muon beam at CERN. The experiment used the polarized proton and deuteron targets. The structure function g1p(x) and g1d(x) were determined from the asymmetries of the spin-dependent event rates in the range of 0.0032>=10 GeV2. Using the first moments of these structure functions an agreement with the Bjorken sum rule prediction was found within one standard deviation. The first moments of g1(x), for both proton and deuteron, are smaller than the Ellis-Jaffe sum rule prediction. This disagreement can be interpreted in terms of negative polarization of the strange sea in the nucleon. The singlet part of the axial current matrix element can be interpreted as an overall spin carried by quarks in the nucleon. Its value is significantly smaller than nucleon spin. Semi-inclusive asymmetries of yields of positive and negative hadrons produced on both targets were also measured and analysed in term of quark-parton model, together with inclusive asymmetries. From this analysis the quark spin distributions were determined, separately for valence u and d quarks and for non-strange sea quarks. Valence u quarks are positively polarized and their polarization increases with x. Valence d quarks are negatively polarized and their polarization does not exhibit any x-dependence. The non-strange sea is unpolarized in the whole measured range of x. The first moments of the valance quark spin distributions were found consistent with the values obtained from weak decay constants F and D and their second moments are consistent with lattice QCD calculations. In the QCD analysis of the world data the first moment of the gluon spin distribution was found with a large error. Also, a search for a non-perturbative anomaly at high x was done on the world data and the result was consistent with null. An extensive discussion of the SMC results and a comparison with results of SLAC experiment is presented. The new experiment of the COMPASS Collaboration, approved and being currently in preparation at CERN, was presented. The main physics issues of the muon part of this experiment, which are the gluon polarization and a continuation of the physics program of the SMC, were discussed. (author)
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 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)
Future exploration of the nucleon structure at COMPASS
International Nuclear Information System (INIS)
Up to now, COMPASS experiment essentially focussed, in it's program with muon beams, on studying aspects of the longitudinal momentum structure of the nucleon in the collinear approximation, like ?q(x) and ?G/G(x). However, quarks can also have intrinsic transverse momentum in the nucleon, which give rise to a new class of Transverse Momentum Distribution (TMD) Parton Distribution Functions. As an example, Sievers function has been measured by both COMPASS and HERMES to be non zero on the proton, paving thus the way for more precise investigations. It is precisely the goal of the new COMPASS phase II proposal to investigate in more detail new transverse description of the nucleon structure. Deeply Virtual Compton Scattering (DVCS) will allow studies in the transverse space via Generalized Parton Distributions (GPDs). Transverse Mometum Dependent PDFs will essentially be studied in Drell-Yan (DY) reaction and SIDIS, and some universality arguments in QCD imply different signs for Sievers and Boer-Mulders functions in DY and SIDIS.
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.)
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.)
Scaling Function, Spectral Function and Nucleon Momentum Distribution in Nuclei
Antonov, A N; Caballero, J A; Barbaro, M B; Udias, J M; de Guerra, E Moya; Donnelly, T W
2011-01-01
The link between the scaling function extracted from the analysis of (e,e') cross sections and the spectral function/momentum distribution in nuclei is revisited. Several descriptions of the spectral function based on the independent particle model are employed, together with the inclusion of nucleon correlations, and effects of the energy dependence arising from the width of the hole states are investigated. Although some of these approaches provide rough overall agreement with data, they are not found to be capable of reproducing one of the distinctive features of the experimental scaling function, namely its asymmetry. However, the addition of final-state interactions, incorporated in the present study using either relativistic mean field theory or via a complex optical potential, does lead to asymmetric scaling functions in accordance with data. The present analysis seems to indicate that final-state interactions constitute an essential ingredient and are required to provide a proper description of the ex...
Nucleon structure function at small ?
International Nuclear Information System (INIS)
This is a status report on the behaviour of deeply inelastic scattering in the low x region, where a new physics to be expected. It is bound to be theoretical review, since there is no data available at truely small values of x, say x -3. New data from HERA are anticipated and I am viewing on this talk as summary of the theoretical situation in the region of small x, as is just before this new area of physics will be studied experimentally. This is an extended version of the talk which was presented at EP-HEP 91 Conference. (orig.)
Structure and spin of the nucleon
Directory of Open Access Journals (Sweden)
Avakian H.
2014-03-01
Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL. TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC, FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Nucleon Excited State Wave Functions from Lattice QCD
Roberts, Dale S; Leinweber, Derek B
2013-01-01
We apply the eigenvectors from a variational analysis to successfully extract the wave functions of even-parity excited states of the nucleon, including the Roper. We explore the first four states in the spectrum excited by the standard nucleon interpolating field. We find that the states exhibit a structure qualitatively consistent with a constituent quark model, where the ground, first-, second- and third-excited states have 0, 1, 2, and 3 nodes in the radial wave function of the d-quark about two $u$ quarks at the origin. Moreover the radial amplitude of the probability distribution is similar to that predicted by constituent quark models. We present a detailed examination of the quark-mass dependence of the probability distributions for these states, searching for a nontrivial role for the multi-particle components mixed in the finite-volume QCD eigenstates. Finally we examine the dependence of the d-quark probability distribution on the positions of the two u quarks. The results are fascinating, with the...
International Nuclear Information System (INIS)
This review focuses on the discussion of three key results of nucleon structure calculations on the lattice. These three results are the quark contribution to the nucleon spin, Jq, the nucleon-? transition form factors, and the nucleon axial coupling, gA. The importance for phenomenology and experiment is discussed and the requirements for future simulations are pointed out. (orig.)
Nucleon structure by Lattice QCD computations with twisted mass fermions
International Nuclear Information System (INIS)
Understanding the structure of the nucleon from quantum chromodynamics (QCD) is one of the greatest challenges of hadronic physics. Only lattice QCD allows to determine numerically the values of the observables from ab-initio principles. This thesis aims to study the nucleon form factors and the first moments of partons distribution functions by using a discretized action with twisted mass fermions. As main advantage, the discretization effects are suppressed at first order in the lattice spacing. In addition, the set of simulations allows a good control of the systematical errors. After reviewing the computation techniques, the results obtained for a wide range of parameters are presented, with lattice spacings varying from 0.0056 fm to 0.089 fm, spatial volumes from 2.1 up to 2.7 fm and several pion masses in the range of 260-470 MeV. The vector renormalization constant was determined in the nucleon sector with improved precision. Concerning the electric charge radius, we found a finite volume effect that provides a key towards an explanation of the chiral dependence of the physical point. The results for the magnetic moment, the axial charge, the magnetic and axial charge radii, the momentum and spin fractions carried by the quarks show no dependence on the lattice spacing nor volume. In our range of pion masses, their values show a deviation from the experimental values. Their chiral behaviour do not exhibit the curvature predicted by the chiral perturbation theory which could explain the apparent discrepancy. (author)
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.
Nucleon structure in the search for new physics
Young, Ross D.
2011-01-01
We report on recent results on nucleon structure that are helping guide the search for new physics at the precision frontier. Results discussed include the electroweak elastic form factors, charge symmetry breaking in parton distributions and the strangeness content of the nucleon.
Nuclear energy density functional from chiral two-nucleon and three-nucleon interactions
Energy Technology Data Exchange (ETDEWEB)
Holt, J.W.; Kaiser, N.; Weise, W. [Technische Universitaet Muenchen, Physik Department, Garching (Germany)
2011-10-15
An improved density-matrix expansion is used to calculate the nuclear energy density functional from chiral two- and three-nucleon interactions. The two-body interaction comprises long-range one- and two-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition we employ the leading-order chiral three-nucleon interaction with its parameters c{sub E}, c{sub D} and c{sub 1,3,4} fixed in calculations of nuclear few-body systems. With this input the nuclear energy density functional is derived to first order in the two- and three-nucleon interaction. We find that the strength functions F{sub {nabla}}({rho}) and F{sub so} ({rho}) of the surface and spin-orbit terms compare in the relevant density range reasonably with the results of phenomenological Skyrme forces. However, an improved description requires (at least) the treatment of the two-body interaction to second order. This observation is in line with the deficiencies in the nuclear matter equations of state anti E({rho}) that remain in the Hartree-Fock approximation with low-momentum two- and three-nucleon interactions. (orig.)
Nuclear energy density functional from chiral two-nucleon aaand three-nucleon interactions
Holt, J. W.; Kaiser, N.; Weise, W.
2011-10-01
An improved density-matrix expansion is used to calculate the nuclear energy density functional from chiral two- and three-nucleon interactions. The two-body interaction comprises long-range one- and two-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition we employ the leading-order chiral three-nucleon interaction with its parameters c E , c D and c 1,3,4 fixed in calculations of nuclear few-body systems. With this input the nuclear energy density functional is derived to first order in the two- and three-nucleon interaction. We find that the strength functions F ?( ?) and F so ( ?) of the surface and spin-orbit terms compare in the relevant density range reasonably with the results of phenomenological Skyrme forces. However, an improved description requires (at least) the treatment of the two-body interaction to second order. This observation is in line with the deficiencies in the nuclear matter equations of state bar E(? ) that remain in the Hartree-Fock approximation with low-momentum two- and three-nucleon interactions.
Photoproduction of nucleon resonances and their structure
International Nuclear Information System (INIS)
Review of available data on radiative decay of non-strange nucleon resonators is presented. The radiative decay amplirude values presented by different authors differ appreciably, which testifies to availability of significant systematic errors. Determination of amplitude of electric quadrupole excitation of ?33(1232) isobar and R11(1440) Roper resonance, arousing great interest due to possibilities of studying features of quark interaction in nucleons and search of hydride (quark-gluon) states, is considered in details. 87 refs.; 5 tabs
Search for narrow structure in the nucleon-nucleon system
International Nuclear Information System (INIS)
The energy dependent measurements of the analyzing power, Ay, in proton-proton elastic scattering and the pp??+d reaction were made during polarized beam acceleration, using an internal target inserted into the beam every acceleration cycle. A left-right symmetric four-arm detector system was used to detect the forward-scattered proton (deuteron) in coincidence with the conjugate backward-recoil proton (pion) at the laboratory backward angle of 68deg. The energy bin size ranged from 4 to 17 MeV for pp elastic scattering and from 10 to 30 MeV for the pp??d reaction. The statistical uncertainty ?Ay for each energy bin is ?0.01 in pp elastic scattering and is ?0.06 in the pp??d reaction. Narrow structures were found in the two-proton invariant mass distribution of Ay for pp elastic scattering. (author)
International Nuclear Information System (INIS)
We measured the production of massive muon pairs on a platinum target by pions of 200 and 280 GeV/c. The following number of dimuon events have been collected for M > 4 GeV/c2. (a) ?- of 200 GeV/c: approx. 5900 events; (b) ?+ of 200 GeV/c: approx. 2200 events; (c) ?- of 280 GeV/c: approx. 5700 events. These data were analysed in terms of the Drell-Yan model in order to obtain the pion and nucleon structure functions, which are parametrised with expressions of the form xsup(?)(1 - x)sup(?). Our results are compared to the structure functions obtained in other experiments. (orig.)
Negele, John
2014-03-01
The inaugural Feshbach prize recognizes lifetime contributions to understanding the structure of the basic building blocks of matter in terms of their constituents and the fundamental interactions between them. Initially this meant understanding the structure of nuclei in terms of nucleons interacting via nucleon-nucleon forces. I will describe a density functional theory for calculating nuclear properties directly from nuclear forces. It identifies mechanisms for ``saturation,'' relates the Skyrme interaction to nuclear forces, and with two parameters characterizing experimentally unknown aspects of nuclear forces yields nuclear binding energies, single particle energies, and charge distributions close to experiment. After the discovery of quarks and QCD, the goal became understanding how the structure of nucleons and ultimately the missing physics in nuclear forces emerge from quarks interacting via QCD. I will explain the use of lattice QCD to calculate the properties of nucleons, show recent results yielding agreement with experiment for the charge and magnetization radii, magnetic moment, and quark momentum fraction, and comment on the prospects for its use to understand aspects of nuclei and nucleon-nucleon interactions. This research was supported in part by the DOE Office of Nuclear Physics under grant #DE-FG02-94ER40818.
Study of excited nucleons and their structure
International Nuclear Information System (INIS)
Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum. (author)
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.
Nucleon spin structure and its connections to various sum rules
Soffer, J.
2004-01-01
Our knowledge on the nucleon spin structure has greatly improved over the last twenty years or so, but still many fundamental questions remain unsolved. I will try to review some of the puzzling aspects of the origin of the nucleon spin. I will emphasize the connection with several sum rules and, when using this tool, the relevance of some kinematic regions for testing them in the QCD dynamics framework.
Energy Technology Data Exchange (ETDEWEB)
Schroers, W. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2007-01-15
This review focuses on the discussion of three key results of nucleon structure calculations on the lattice. These three results are the quark contribution to the nucleon spin, J{sub q}, the nucleon-{delta} transition form factors, and the nucleon axial coupling, g{sub A}. The importance for phenomenology and experiment is discussed and the requirements for future simulations are pointed out. (orig.)
Polarized Parton Distribution Functions in the Nucleon
Goto, Y; Hirai, M; Horikawa, H; Kumano, S; Miyama, M; Mori, T; Saitô, N; Shibata, T A; Taniguchi, E; Yamanishi, T
2000-01-01
Polarized parton distribution functions are determined by using world data from the longitudinally polarized deep inelastic scattering experiments. A new parametrization of the parton distribution functions is adopted by taking into account the positivity and the counting rule. From the fit to the asymmetry data A_1, the polarized distribution functions of u and d valence quarks, sea quarks, and gluon are obtained. The results indicate that the quark spin content is \\Delta\\Sigma=0.20 and 0.05 in the leading order (LO) and the next-to-leading-order (NLO) MS-bar scheme, respectively. However, if x dependence of the sea-quark distribution is fixed at small x by "perturbative QCD" and Regge theory, it becomes \\Delta \\Sigma=0.24 ~ 0.28 in the NLO. The small-x behavior cannot be uniquely determined by the existing data, which indicates the importance of future experiments. From our analysis, we propose one set of LO distributions and two sets of NLO ones as the longitudinally-polarized parton distribution functions...
Spin structure of nucleon in QCD: inclusive and exclusive processes
International Nuclear Information System (INIS)
There are two basically independent ways to describe the nucleon spin structure. One is related to quark and gluon spins and another one to their total angular momenta. The latter spin structure may be studied, in principle, in hard exclusive processes
Nuclear energy density functional from chiral pion-nucleon dynamics
International Nuclear Information System (INIS)
We calculate the nuclear energy density functional relevant for N=Z even-even nuclei in the framework of chiral perturbation theory. 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 in the region below the nuclear matter saturation density the effective nucleon mass M-bar*(?) deviates by at most 15% from its free space value M, with 0.89M-3 and M-bar*(?)>M for higher densities. The parameterfree strength of the (???)2-term, F?(kf), is at saturation density comparable to that of phenomenological Skyrme forces. The magnitude of FJ(kf) accompanying the squared spin-orbit density J? 2 comes out considerably larger. The strength of the nuclear spin-orbit interaction, Fso(kf), as given by iterated one-pion exchange is about half as large as the corresponding empirical value, however, with the wrong negative sign. The novel density dependencies of M-bar*(?) and F?,so,J(kf) as predicted by our parameterfree (leading order) calculation should be examined in nuclear structure calculations (introducing at least an additional short range spin-orbit contribution constant in density)ution constant in density)
Structure of nucleons at small distances
International Nuclear Information System (INIS)
We report here the observation of surprisingly simple behaviors in the massive-hadron-pair (m>2 GeV) production from proton-nucleon collisions. With a 28.6-GeV incident proton beam and a pair spectrometer to detect the hadrons, the measured cross section decreases like d2sigma/dxdmproportionale-5/subm/ and can be grouped into three groups: ?-+p; ?++?-, p+p, K-+p; and K-+?+, ?++p. Within a given group the yield is the same to plus-or-minus20%; different groups are separated by a factor of approx.10 from each other
Experimental study of the nucleon spin structure
Energy Technology Data Exchange (ETDEWEB)
Litmaath, M.F.
1996-05-07
After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.).
Shape of hadron structure functions
International Nuclear Information System (INIS)
The hypothesis that, in the leading twist approximation and to all orders of perturbative QCD, there exists a momentum scale Q02 at which hadrons are pure valence quark (or antiquark) bound states gives good results for nucleon, pion, and kaon structure functions. 2 figures
Superscaling, scaling functions, and nucleon momentum distributions in nuclei
Antonov, A. N.; Gaidarov, M. K.; Ivanov, M. V.; Kadrev, D. N.; Moya Guerra, Elvira; Sarriguren, Pedro; Udias, J. M.
2005-01-01
The scaling functions $f(\\psi')$ and $F(y)$ from the $\\psi'$- and $y$-scaling analyses of inclusive electron scattering from nuclei are explored within the coherent density fluctuation model (CDFM). In addition to the CDFM formulation in which the local density distribution is used, we introduce a new equivalent formulation of the CDFM based on the one-body nucleon momentum distribution (NMD). Special attention is paid to the different ways in which the excitation energy of ...
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.)
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
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.)
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.
Flavor structure of the nucleon sea from lattice QCD
Lin, Huey-Wen; Chen, Jiunn-Wei; Cohen, Saul D.; Ji, Xiangdong
2015-03-01
We present the first direct lattice calculation of the isovector sea-quark distributions in the nucleon within the framework of the large-momentum effective field theory proposed recently. We use Nf=2 +1 +1 highly improved staggered quarks lattice gauge ensembles (generated by the MILC Collaboration) and clover valence fermions with pion mass 310 MeV. We establish the convergence of the result as the nucleon momentum increases within the uncertainty of the calculation. Although the lattice systematics are not yet fully under control, we obtain some qualitative features of the flavor structure of the nucleon sea: d ¯ (x )>u ¯ (x ) leading to the violation of the Gottfried sum rule, ? u ¯(x )>? d ¯(x ) as indicated by the STAR data at large and small leptonic pseudorapidity.
Atti, Claudio Ciofi Degli; West, Geoffrey B.
1999-01-01
Some systematic general features of y-scaling structure functions, which are essentially independent of detailed dynamics, are pointed out. Their physical interpretation in terms of general characteristics, such as a mean field description and nucleon-nucleon correlations, is given and their relationship to the momentum distributions illustrated. A new relativistic scaling variable is proposed which incorporates the momentum dependence of the excitation energy of the (A-1) s...
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)
International Nuclear Information System (INIS)
Using the structure functions F2 measured in E.M.C., we have extracted the following values for the QCD scale parameter ?, at next to leading order: hydrogen target: ?sub(MS) = 139(+170-100)MeV; iron target: ?sub(MS) = 170(+160-100)MeV we have performed a study of the 1/Q2 effects on the Q2 domain covered by SLAC and E.M.C. We have extracted the ratio R = sigma sub(L)/sigma sub(T) for various chi bins and compared it with other experimental values and theoretical predictions. The mean value = 0+-.15 was found and is compatible with zero
Investigating nucleon and meson structure through Drell-Yan processes
International Nuclear Information System (INIS)
We investigate the magnitude of charge symmetry violation (CSV) at high energies. At the quark level, charge symmetry involves identity under the interchange of up and down quarks. We predict large CSV effects [of order 10%] for the minority quarks, i.e. the down quark in the proton and up quark in the neutron. CSV effects are predicted to be substantially smaller for the majority quarks (up quark in proton, down quark in neutron). We show the origin of the difference for these two cases. Since our predicted effect is surprisingly large, we suggest experiments which could directly measure CSV quantities. We show that measurement of pion-induced Drell-Yan (DY) processes on proton and deuteron targets could isolate CSV terms for both nucleon and pion. We also estimate the magnitude of CSV for pion distributions. If sufficiently intense meson beams were available, one could investigate details of mesonic structure functions through meson-nucleus DY processes. We show that ?+ and ?- DY measurements on isoscalar nuclear targets could provide quantitative information on pion sea quark distributions, which are presently poorly determined. (author). 18 refs., 6 figs
q?? fragmentation function and nucleon transversity distribution in a diquark model
International Nuclear Information System (INIS)
Based on a simple quark-diquark model, we propose a set of unpolarized, longitudinally polarized and transversely polarized fragmentation functions for the ? by fitting the unpolarized ? production data in e+e- annihilation. It is found that the helicity structure of the obtained ? fragmentation functions is supported by the all available experimental data on the longitudinal ? 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 ? 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.
Nucleon structure in a light-front quark model consistent with quark counting rules and data
Gutsche, Thomas; Schmidt, Ivan; Vega, Alfredo
2014-01-01
Using global fits of valence u and d quark parton distributions and data on quark and nucleon form factors in the Euclidean region, we derive a light-front quark model for the nucleon structure consistent with quark counting rules.
International Nuclear Information System (INIS)
In the Cloudy Bag Model hadrons are treated as quarks confined in an M.I.T. bag that is surrounded by a cloud of pions. Computations of the charge and magnetism distributions of nucleons and baryons, pion-nucleon scattering, and the strong and electromagnetic decays of mesons are discussed. Agreement with experimental results is excellent if the nucleon bag radius is in the range between 0.8 and 1.1 fm. Underlying qualitative reasons which cause the pionic corrections to be of the obtained sizes are analyzed. If bags are of such reasonably large sizes, nucleon bags in nuclei will often come into contact. As a result one needs to consider whether explicit quark degrees of freedom are relevant for Nuclear Physics. To study such possibilities a model which treats a nucleus as a collection of baryons, pions and six-quark bags is discussed. In particular, the short distance part of a nucleon-nucleon wave function is treated as six quarks confined in a bag. This approach is used to study the proton-proton weak interaction, the asymptotic D to S state ratio of the deuteron, the pp ? d? reaction, the charge density of /sup 3/He, magnetic moments of /sup 3/He and /sup 3/H and, the /sup 3/He-/sup 3/H binding energy difference. It is found that quark effects are very relevant for understanding nuclear properties
Structure and spin of the nucleon
Avakian H.
2014-01-01
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 Asym...
Studies of the three-nucleon system properties using the interpolating amplitude scattering function
International Nuclear Information System (INIS)
The three-nucleon motion problem is formulated and investigated using the interpolating function method. The pole functions corresponding to the bound state of the three-nucleon system and the low energy functions interpolating the nd-scattering length are calculated for a separable potential
Covariant nucleon wave function with S, D, and P-state components
Energy Technology Data Exchange (ETDEWEB)
Franz Gross, G. Ramalho, M. T. Pena
2012-05-01
Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.
Covariant nucleon wave function with S, D, and P-state components
Gross, Franz; Pena, M T
2012-01-01
Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.
Feasibility studies for nucleon structure measurements with PANDA
Directory of Open Access Journals (Sweden)
Atomssa Ermias
2014-01-01
Full Text Available The study of nucleon structure is one of the main physics goals of PANDA to be built at the FAIR accelerator complex. The excellent particle identification performance of the PANDA detector will enable measurements of exclusive channels p? p ? e+e? and p? p ? ?0 J/? ? ?0e+e? to extract the electromagnetic form factors of protons and ?-nucleon Transition Distribution Amplitudes (?-N TDAs. After a brief description of the PANDA apparatus and a method to handle momentum resolution degradation due to Bremsstrahlung, the physics of ?-N TDAs is discussed. An estimate for the expected signal to background ratio for p? p ? ?0 J/? ? ?0e+e? that takes into account the main background source is given.
Feasibility studies for nucleon structure measurements with PANDA
Atomssa, Ermias; Ma, Binsong
2014-11-01
The study of nucleon structure is one of the main physics goals of PANDA to be built at the FAIR accelerator complex. The excellent particle identification performance of the PANDA detector will enable measurements of exclusive channels p¯ p ? e+e- and p¯ p ? ?0 J/? ? ?0e+e- to extract the electromagnetic form factors of protons and ?-nucleon Transition Distribution Amplitudes (?-N TDAs). After a brief description of the PANDA apparatus and a method to handle momentum resolution degradation due to Bremsstrahlung, the physics of ?-N TDAs is discussed. An estimate for the expected signal to background ratio for p¯ p ? ?0 J/? ? ?0e+e- that takes into account the main background source is given.
Nuclear energy density functional from chiral pion-nucleon dynamics
Kaiser, N; Weise, W
2003-01-01
We calculate the nuclear energy density functional relevant for N=Z even-even nuclei in the systematic framework of chiral perturbation theory. 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 very good equation of state of isospin symmetric nuclear matter. We find that in the region below nuclear matter saturation density the effective nucleon mass $\\widetilde M^*(\\rho)$ deviates by at most 15% from its free space value $M$, with $0.89MM$ for higher densities. The parameterfree strength of the $(\\vec\
Nuclear energy density functional from chiral pion-nucleon dynamics
Energy Technology Data Exchange (ETDEWEB)
Kaiser, Norbert; Weise, Wolfram [Physik-Department, Technische Universitaet Muenchen, Garching (Germany)
2010-07-01
We use a recently improved density-matrix expansion (B. Gebremariam, T. Duguet, S.K. Bogner, nucl-th:0910.4979) to calculate the nuclear energy density functional in chiral perturbation theory. Our calculation treats systematically the effects from 1{pi}-exchange, iterated 1{pi}-exchange, and irreducible 2{pi}-exchange with intermediate {delta}-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass M{sup *}({rho}) is identical to the one of Fermi-liquid theory. The strength F{sub {nabla}}({rho}) of the (vector {nabla}{rho}){sup 2} surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region {rho}{sub 0}/2 <{rho}< {rho}{sub 0}. The spin-orbit coupling strength F{sub so}({rho}) receives contributions from iterated 1{pi}-exchange (of the ''wrong sign'') and from three-nucleon interactions mediated by 2{pi}-exchange with virtual {delta}-excitation (of the ''correct sign''). In the region around {rho}{sub 0}/2 {approx_equal}0.08 fm{sup -3} where the spin-orbit interaction in nuclei gains most of its weight these two components tend to cancel, thus leaving all room for the short-range spin-orbit interaction. The strength function F{sub J}({rho}) multiplying the squared spin-orbit density vector J{sup 2} is also studied.
Pion-nucleon interaction in the P11 partial wave and the pion-nucleon vertex function
International Nuclear Information System (INIS)
We have studied pion-nucleon interaction in the P11 channel considering its important role in the absorption and production of the pion by nuclei. Specifically we show that the total P11 t-matrix (or amplitude) can be naturally decomposed into two parts: the direct (and dressed) pole part and the non-pole part. It is then easy to observe that individually these two parts can be large but tend to nearly cancel each other and produce small and negative phase shift values from threshold to Tsub(Lab)sup? approximately 170 MeV and that at higher energies the non-pole term dominates giving positive phase shift values. We then try to find the parametrisation of this partial wave t-matrix within the framework of the Blankenbecler-Sugar reduction. As a biproduct we have obtained the ?NN vertex function (with one nucleon off-mass-shell) and the dressed nucleon propagator
Studies of nucleon resonance structure in exclusive meson electroproduction
International Nuclear Information System (INIS)
Studies of the structure of excited baryons are key factors to the N* program at Jefferson Lab (JLab). Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electroproduction off protons, along with Quantum Chromodynamics (QCD)-based approaches to the theoretical interpretation of these fundamental quantities. This program will afford access to the dynamics of the nonperturbative strong interaction responsible for resonance formation, and will be crucial in understanding the nature of confinement and dynamical chiral symmetry breaking in baryons, and how excited nucleons emerge from QCD. (author)
Low temperature polarized target for spin structure studies of nucleons at COMPASS
Pesek, Michael
In presented thesis we describe concept of Deep Inelastic Scattering of leptons on nucleons in context of nucleon spin structure studies. Both polarized and unpolarized cases are discussed and concept of Transverse Momentum Dependent Parton Distribution Functions (TMD PDF) is introduced. The possibility of TMDs measurement using Semi-inclusive DIS (SIDIS) is described along with related results from COMPASS experiment. The future Drell-Yan programme at COMPASS is briefly mentioned and its importance is presented on the universality test i.e. change of sign of T-odd TMDs when measured in Drell-Yan and SIDIS. The importance of Polarized Target (PT) for spin structure studies is highlighted and principles of Dynamic Nuclear Polarization (DNP) are given using both Solid effect and spin temperature concept. COMPASS experiment is described in many details with accent given to PT. Finally the thermal equilibrium (TE) calibration procedure is described and carried out for 2010 and 2011 physics runs at COMPASS. The av...
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...
Meson polarized distribution function and mass dependence of the nucleon parton densities
Mirjalili, A.; Keshavarzian, K.
2014-08-01
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 distributions and the available experimental data validates the suggested solutions for separated evolutions.
Polarized lepton-nucleon scattering
International Nuclear Information System (INIS)
Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions
Polarized lepton-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Hughes, E.
1994-02-01
Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions.
A microscopic understanding of the structure functions of finite nuclei
International Nuclear Information System (INIS)
A number of relatively successful quark model descriptions of nuclear matter have recently been developed, based on a mean-field description of non-overlapping nucleon bags bound by the self-consistent exchange of scalar (?) and vector (?) mesons. The meson fields modify the internal quark motion in the nucleon bag in medium and this induces a saturation mechanism for nuclear matter. The model gives a nuclear compressibility around 220 MeV and provides a rather satisfactory interpretation of nuclear matter properties. Furthermore, it has recently been shown that the twist-2 valence quark distributions of the free nucleon calculated in the MIT bag model are in reasonable agreement with world data. By using a local density approximation we combine these developments to microscopically investigate the structure functions of finite nuclei. The effect of nuclear shadowing and antishadowing is taken into account phenomenologically. The model can quantitatively reproduce the existing experimental data - the so-called European Muon Collaboration (EMC) effect. We show that the quark degrees of freedom in nuclei and the final state interaction between the debris of the struck nucleon and the residual nucleus both play important roles in the nuclear structure functions. Thus the conventional treatment based on nucleon binding within the impulse approximation is quantitatively unreliable. We also study the effects of the self-coupling terms of the ? field and nucleon-nucleon cms of the ? field and nucleon-nucleon correlations on some nuclear matter properties and the nuclear structure functions. ((orig.))
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
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)
Revisiting parameterization of proton structure function
International Nuclear Information System (INIS)
Measurement of nucleon structure functions has attracted the attention of theoretical and experimental high energy physicist since decades. Theoretically, the structure functions of proton are determined by QCD fits. This work reports a fractal inspired parameterization for the structure function of proton. In some earlier work by the author, a fractal model of proton structure was proposed with few fitted parameters, which was then applied to few other aspects of nucleon structure. This paper reports a new parameterization applicable in a wide range of x and Q2 of deep inelastic scattering in the light of recent data. The calculated chi square value proves the goodness of fit and therefore the model is expected to have wider range of applicability. (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}?.
Nonequilibrium distribution functions of nucleons in relativistic nucleus-nucleus collisions
Directory of Open Access Journals (Sweden)
D. Anchishkin
2013-03-01
Full Text Available The collision smearing of the nucleon momenta about their initial values during relativistic nucleus-nucleus collisions is investigated. To a certain degree, our model belongs to the transport type, and we investigate the evolution of the nucleon system created at a nucleus-nucleus collision. However, we parameterize this development by the number of collisions of every particle during evolution rather than by the time variable. It is assumed that the group of nucleons which leave the system after the same number of collisions can be joined in a particular statistical ensemble. The nucleon nonequilibrium distribution functions are derived which depend on a certain number of collisions of a nucleon before a freeze-out.
International Nuclear Information System (INIS)
We have performed a separation of the longitudinal and transverse structure functions for the 40Ca(e,e'p)39K reaction in the quasi-elastic region. Their ratio (L/T) is found reduced by about 30% from the Distorted Wave Impulse Approximation prediction. This result is compatible with the quenching of the Coulomb Sum-Rule observed in the inclusive ee' reaction. Since a possible swelling of the nucleon in nuclear matter has been advocated to explain this quenching, we have also measured the q-dependence of both structure functions to test this hypothesis. The results are not in favour of a large modification of the electromagnetic radius of the nucleon. From the transverse component, an upper limit of 5% can be derived for a possible increase of the radius
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
Measurements of the neutron polarized structure function at SLAC
International Nuclear Information System (INIS)
Detailed measurements of unpolarized or spin-averaged nucleon structure functions over the past two decades have led to detailed knowledge of the nucleon's internal momentum distribution. Polarized nucleon structure function measurements, which probe the nucleon's internal spin distribution, started at SLAC in 1976. E-142 has recently measured the neutron polarized structure function g1n(x) over the range 0.03 ? x ? 0.6 at an average Q2 of 2 GeV2 and found the integral In = ?01g1n(x)dx=-0.022±0.011. E-143, which took data recently, has measured g1p and g14. Two more experiments (E-154 and E-155) will extend these measurements to lower x and higher Q2
Quark Structure of the Nucleon and Angular Asymmetry of Proton-Neutron Hard Elastic Scattering
Granados, Carlos G.; Sargsian, Misak M.
2009-01-01
We investigate an asymmetry in the angular distribution of hard elastic proton-neutron scattering with respect to 90deg center of mass scattering angle. We demonstrate that the magnitude of the angular asymmetry is related to the helicity-isospin symmetry of the quark wave function of the nucleon. Our estimate of the asymmetry within the quark-interchange model of hard scattering demonstrates that the quark wave function of a nucleon based on the exact SU(6) symmetry predict...
Nuclear energy density functional from chiral two- and three-nucleon interactions
Holt, J W; Weise, W
2011-01-01
An improved density-matrix expansion is used to calculate the nuclear energy density functional from chiral two- and three-nucleon interactions. The two-body interaction comprises long-range one- and two-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition we employ the leading order chiral three-nucleon interaction with its parameters $c_E, c_D$ and $c_{1,3,4}$ fixed in calculations of nuclear few-body systems. With this input the nuclear energy density functional is derived to first order in the two- and three-nucleon interaction. We find that the strength functions $F_\
International Nuclear Information System (INIS)
To describe EMC-effect relations between the structure functions (SF) of a nucleus and constituent nucleons and also the moments of investigated SF are studied. To take account of exponential with respect to 1/Q2 corrections an expression for SF nucleus Nachtman moments in terms of nucleon SF Nachtman moments and nucleus wave functions is evaluated. Relation between nucleus SF and SF constituent nucleon is considered. It is noted that obtained expressions are suitable for description of contribution of different mechanisms to EMC effect
Spin structure of the nucleon and axial anomaly
International Nuclear Information System (INIS)
The gluon spin distribution function is shown to contribute to the spin structure of a proton via the axial anomaly. It modifies the original Ellis-Jaffe sum rule and can help in resolving the ''Spin Crisis''. The axial anomaly renormalization, the evolution equations and the connection of the quark content of the proton spin with the ?'-meson coupling constants are also considered. (orig.)
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.)
Polarized structure functions up to collider energies
International Nuclear Information System (INIS)
A new set of spin-dependent structure functions for quarks and gluons inside a polarized nucleon is presented. This is the only available set which satisfies all the sum rules and analytic requirements and is valid in the kinematic range 10-5?x?0.9 and 5?Q2?5x108 GeV2, the effects of heavier flavours being taken into account. (orig.)
Nuclear energy density functional from chiral two- and three-nucleon interactions
Holt, J. W.; Kaiser, N.; Weise, W.
2011-01-01
An improved density-matrix expansion is used to calculate the nuclear energy density functional from chiral two- and three-nucleon interactions. The two-body interaction comprises long-range one- and two-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition we employ the leading order chiral three-nucleon interaction with its parameters $c_E, c_D$ and $c_{1,3,4}$ fixed in calculations of nuclear few-body systems. With ...
Nucleon structure at large x: nuclear effects in deuterium
Melnitchouk, W.
2010-01-01
I review quark momentum distributions in the nucleon at large momentum fractions x. Particular attention is paid to the impact of nuclear effects in deuterium on the d/u quark distribution ratio as x -> 1. A new global study of parton distributions, using less restrictive kinematic cuts in Q^2 and W^2, finds strong suppression of the d quark distribution once nuclear corrections are accounted for.
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
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
Kaiser, N.
2012-01-01
A recent calculation of the nuclear energy density functional from chiral two- and three-nucleon forces is extended to the isovector terms pertaining to different proton and neutron densities. An improved density-matrix expansion is adapted to the situation of small isospin-asymmetries and used to calculate in the Hartree-Fock approximation the density-dependent strength functions associated with the isovector terms. The two-body interaction comprises of long-range multi-pio...
Arrington, J.; Coester, F.; Holt, R. J.; Lee, T. -S. H.
2008-01-01
Neutron structure functions can be extracted from proton and deuteron data and a representation of the deuteron structure. This procedure does not require DIS approximations or quark structure assumptions. We find that the results depend critically on properly accounting for the Q^2 dependence of proton and deuteron data. We interpolate the data to fixed Q^2, and extract the ratio of neutron to proton structure functions. The extracted ratio decreases with increasing x, up t...
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
Lattice investigation of nucleon structure at light quark masses
International Nuclear Information System (INIS)
Lattice simulations of hadronic structure are now reaching a level where they are able to not only complement, but also provide guidance to current and forthcoming experimental programmes at, e.g. Jefferson Lab, COMPASS/CERN and FAIR/GSI. By considering new simulations at low quark masses and on large volumes, we review the recent progress that has been made in this exciting area by the QCDSF/UKQCD collaboration. In particular, results obtained close to the physical point for several quantities, including electromagnetic form factors and moments of ordinary parton distribution functions, show some indication of approaching their phenomenological values.
Statistical description of the flavor structure of the nucleon sea
Soffer, Jacques; Buccella, Franco
2014-01-01
The theoretical foundations of the quantum statistical approach to parton distributions are reviewed together with the phenomenological motivations from a few specific features of Deep Inelastic Scattering data. The chiral properties of QCD lead to strong relations between quarks and antiquarks distributions and automatically account for the flavor and helicity symmetry breaking of the sea. We are able to describe both unpolarized and polarized structure functions in terms of a small number of parameters. The extension to include their transverse momentum dependence will be also briefly considered.
Shell structure and few-nucleon removal in intranuclear cascade
Mancusi, Davide; Carbonell, Jaume; Cugnon, Joseph; David, Jean-Christophe; Leray, Sylvie
2014-01-01
It is well known that intranuclear-cascade models generally overestimate the cross sections for one-proton removal from heavy, stable nuclei by a high-energy proton beam, but they yield reasonable predictions for one-neutron removal from the same nuclei and for one-nucleon removal from light targets. We use simple shell-model calculations to investigate the reasons of this deficiency. We find that a correct description of the neutron skin and of the energy density in the nuclear surface is crucial for the aforementioned observables. Neither ingredient is sufficient if taken separately.
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.
A Review of Nucleon Spin Calculations in Lattice QCD
Lin, Huey-Wen
2009-01-01
We review recent progress on lattice calculations of nucleon spin structure, including the parton distribution functions, form factors, generalization parton distributions, and recent developments in lattice techniques.
Gebremariam, B.; Bogner, S. K.; Duguet, T.
2011-02-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N2LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.
Energy Technology Data Exchange (ETDEWEB)
Gebremariam, B., E-mail: gebremar@gmail.co [National Superconducting Cyclotron Laboratory, 1 Cyclotron Laboratory, East-Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Bogner, S.K., E-mail: bogner@nscl.msu.ed [National Superconducting Cyclotron Laboratory, 1 Cyclotron Laboratory, East-Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Duguet, T., E-mail: thomas.duguet@cea.f [National Superconducting Cyclotron Laboratory, 1 Cyclotron Laboratory, East-Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); CEA, Centre de Saclay, IRFU/Service de Physique Nucleaire, F-91191 Gif-sur-Yvette (France)
2011-02-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in (arXiv:0910.4979) by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N{sup 2}LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.
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
Nuclear energy density functional from chiral pion-nucleon dynamics
Kaiser, N.; Fritsch, S.; Weise, W.
2002-01-01
We calculate the nuclear energy density functional relevant for N=Z even-even nuclei in the systematic framework of chiral perturbation theory. 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 very good equation of state of isospin symmetric nuclear matter. We find that in the region below nuclear matter sat...
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.
Sepratation energies of nucleons and the energy sum rule of the Green's function method
International Nuclear Information System (INIS)
It is considered the energy sum rule of the Green's function method in connection with nucleon removal experiments. It is pointed out that the reported violation of this sum rule is a consequence of the inappropriateness of the usual practice of identifying observed separation energies with minus ''mean removal energies''. Moreover it is noted that the interpretation of the reported violation of the energy sum rule as a strong indication of the importance of three-body force is unacceptable
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
Kaiser, N.; Weise, W.
2009-01-01
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from $1\\pi$-exchange, iterated $1\\pi$-exchange, and irreducible $2\\pi$-exchange with intermediate $\\Delta$-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass $M^*(\\rho)$ entering the energy density ...
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 proposal is that mainstream programmers can reap the benefits of purely functional programming like easily exploitable parallelism while using familiar structured programming syntax and without knowing concepts like monads. A second advantage is that professional purely functional programmers can often avoid hard to read functional code by using structured programming syntax that is often easier to parse mentally.
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
Kaiser, N.
2012-03-01
A recent calculation of the nuclear energy density functional from chiral two- and three-nucleon forces is extended to the isovector terms pertaining to different proton and neutron densities. An improved density-matrix expansion is adapted to the situation of small isospin asymmetries and used to calculate in the Hartree-Fock approximation the density-dependent strength functions associated with the isovector terms. The two-body interaction comprises of long-range multi-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition, the leading-order chiral three-nucleon interaction is employed with its parameters fixed in computations of nuclear few-body systems. With this input one finds for the asymmetry energy of nuclear matter the value A( ? 0) ? 26.5 MeV, compatible with existing semi-empirical determinations. The strength functions of the isovector surface and spin-orbit coupling terms come out much smaller than those of the analogous isoscalar coupling terms and in the relevant density range one finds agreement with phenomenological Skyrme forces. The specific isospin and density dependences arising from the chiral two- and three-nucleon interactions can be explored and tested in neutron-rich systems.
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
Energy Technology Data Exchange (ETDEWEB)
Kaiser, N. [Technische Universitaet Muenchen, Physik Department T39, Garching (Germany)
2012-03-15
A recent calculation of the nuclear energy density functional from chiral two- and three-nucleon forces is extended to the isovector terms pertaining to different proton and neutron densities. An improved density-matrix expansion is adapted to the situation of small isospin asymmetries and used to calculate in the Hartree-Fock approximation the density-dependent strength functions associated with the isovector terms. The two-body interaction comprises of long-range multi-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition, the leading-order chiral three-nucleon interaction is employed with its parameters fixed in computations of nuclear few-body systems. With this input one finds for the asymmetry energy of nuclear matter the value A({rho}{sub 0}) {approx_equal} 26.5 MeV, compatible with existing semi-empirical determinations. The strength functions of the isovector surface and spin-orbit coupling terms come out much smaller than those of the analogous isoscalar coupling terms and in the relevant density range one finds agreement with phenomenological Skyrme forces. The specific isospin and density dependences arising from the chiral two- and three-nucleon interactions can be explored and tested in neutron-rich systems. (orig.)
Gebremariam, B; Duguet, T
2010-01-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam {\\it et al.} to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N$^2$LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a cutoff-dependent coupling {\\it constant} arising from zero-range contact interactions and a cutoff-independent coupling {\\it function} of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions...
Moments of Spin Structure Functions: Sum Rules and Polarizabilities
Chen, Jian-ping
2010-01-01
Nucleon structure study is one of the most important research areas in modern physics and has challenged us for decades. Spin has played an essential role and often brought surprises and puzzles to the investigation of the nucleon structure and the strong interaction. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture in the strong region of the interaction and of the transition region from the strong to the asymptotic-free region. Insight for some aspects of the theory for the strong interaction, Quantum Chromodynamics (QCD), is gained by exploring lower moments of spin structure functions and their corresponding sum rules. These moments are expressed in terms of an operator-product expansion using quark and gluon degrees of freedom at moderately large momentum transfers. The higher-twist contributions have been examined through the evolution of these moments as the momentum transfer varies...
Low energy structure of the nucleon from chiral effective field theory
Directory of Open Access Journals (Sweden)
Alarcón Jose Manuel
2014-01-01
Full Text Available We present some updated results regarding the scalar and electromagnetic structure of the nucleon obtained by the relativistic formulation of chiral effective field theory with baryons. We compare them with previous determinations available in the literature, and show their relevance for searches of physics beyond the standard model in the low energy frontier.
Effect of nucleon and hadron structure changes in-medium and its impact on observables
Energy Technology Data Exchange (ETDEWEB)
K. Saito; K. Tsushima; A.W. Thomas
2005-07-05
We study the effect of hadron structure changes in a nuclear medium using the quark-meson coupling (QMC) model. The QMC model is based on a mean field description of non-overlapping nucleon (or baryon) bags bound by the self-consistent exchange of scalar and vector mesons in the isoscalar and isovector channels. The model is extended to investigate the properties of finite nuclei, in which, using the Born-Oppenheimer approximation to describe the interacting quark-meson system, one can derive the effective equation of motion for the nucleon (or baryon), as well as the self-consistent equations for the meson mean fields.
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.
Energy Technology Data Exchange (ETDEWEB)
Harraud, P.A.
2010-11-15
Understanding the structure of the nucleon from quantum chromodynamics (QCD) is one of the greatest challenges of hadronic physics. Only lattice QCD allows to determine numerically the values of the observables from ab-initio principles. This thesis aims to study the nucleon form factors and the first moments of partons distribution functions by using a discretized action with twisted mass fermions. As main advantage, the discretization effects are suppressed at first order in the lattice spacing. In addition, the set of simulations allows a good control of the systematical errors. After reviewing the computation techniques, the results obtained for a wide range of parameters are presented, with lattice spacings varying from 0.0056 fm to 0.089 fm, spatial volumes from 2.1 up to 2.7 fm and several pion masses in the range of 260-470 MeV. The vector renormalization constant was determined in the nucleon sector with improved precision. Concerning the electric charge radius, we found a finite volume effect that provides a key towards an explanation of the chiral dependence of the physical point. The results for the magnetic moment, the axial charge, the magnetic and axial charge radii, the momentum and spin fractions carried by the quarks show no dependence on the lattice spacing nor volume. In our range of pion masses, their values show a deviation from the experimental values. Their chiral behaviour do not exhibit the curvature predicted by the chiral perturbation theory which could explain the apparent discrepancy. (author)
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 ...
Self-consistent Green's functions calculation of the nucleon mean-free path
International Nuclear Information System (INIS)
Transport coefficients provide a unique insight into the near-equilibrium behavior of quantum many-body systems. The mean-free path, ?, of a particle within a dense medium is a basic transport coefficient, at the basis of several theoretical concepts and closely related to experimentally measured quantities. Green's functions techniques are particularly well suited to study such transport properties, since they are naturally formulated in the time domain. We present a calculation of the mean-free path of a nucleon in symmetric nuclear matter using self-consistent ladder self-energies extended to the complex energy plane. Our results indicate that, for energies above 50 MeV at densities close to saturation, a nucleon has a mean-free path of 4 to 5 femtometers.
Can a many-nucleon structure be visible in bremsstrahlung emission during $\\alpha$ decay?
Maydanyuk, Sergei P; Zou, Li-Ping
2015-01-01
We analyze if the nucleon structure of the $\\alpha$ decaying nucleus can be visible in the experimental bremsstrahlung spectra of the emitted photons which accompany such a decay. We develop a new formalism of the bremsstrahlung model taking into account distribution of nucleons in the $\\alpha$ decaying nuclear system. We conclude the following: (1) After inclusion of the nucleon structure into the model the calculated bremsstrahlung spectrum is changed very slowly for a majority of the $\\alpha$ decaying nuclei. However, we have observed that visible changes really exist for the $^{106}{\\rm Te}$ nucleus ($Q_{\\alpha}=4.29$ MeV, $T_{1/2}$=70 mks) even for the energy of the emitted photons up to 1 MeV. This nucleus is a good candidate for future experimental study of this task. (2) Inclusion of the nucleon structure into the model increases the bremsstrahlung probability of the emitted photons. (3) We find the following tendencies for obtaining the nuclei, which have bremsstrahlung spectra more sensitive to the ...
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
Kaiser, N
2009-01-01
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from $1\\pi$-exchange, iterated $1\\pi$-exchange, and irreducible $2\\pi$-exchange with intermediate $\\Delta$-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass $M^*(\\rho)$ entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength $F_\
International Nuclear Information System (INIS)
For lattice operators that are relevant to the calculation of moments of nucleon structure functions we investigate the transformation properties under the hypercubic group. We give explicit bases of irreducible subspaces for tensors of rank ?4. (orig.)
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
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
International Nuclear Information System (INIS)
This book contains the lectures given at the International Summer School on Structure and Stability of Nucleon and Nuclear Systems held in Predeal, Romania, in the period August 24 - September 5, 1998. The program of the school covered the following six topics: Nuclear structure (11 lectures); Dynamics of nuclear systems explored by collisions with various projectiles at different energies (8 lectures); Light and heavy cluster emission, cold and ternary fission (4 lectures); ?+-, 2???, 0??? and other neutrino processes; Structure and stability of nucleons (3 lectures); Nuclear matter under exotic conditions (2 lectures). Related to these topics were 17 short communications whose full text can be obtained on request from the authors or from a special issue of Romanian Journal of Physics. The aim of the school was concentrated on the behaviour of nuclear systems under extreme conditions, to understand newly discovered properties of complex nuclei and nucleons, to approach subjects bordering nuclear and particle physics, to identify specific phenomena taking place under conditions met presumably in stars, to investigate the newly explored systems of very short half-life. Exotic phenomena like halo structure of some light nuclei, superdeformation, structure of nuclei lying far from the stability line, specific properties of hot nuclei were also considered in many lectures
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)
In the following, the author tries to summarize the current status of neutrino-nucleon scattering as it bears on contemporary issues regarding the spin structure of the nucleon. It is straightforward to express the electroweak current of a hadron in terms of its underlying electroweak partonic currents. The matrix elements of these currents are, of course, presently uncalculable but may be characterized by form factors extracted from experiment. When neutrinos are used as probes, there are several problems associated with carrying out the required cross section measurements. Active neutrino detectors of necessity contain nuclei more complex than hydrogen. These nuclei create additional backgrounds and create complications of interpretation that make these experiments challenging. However, given the continued demonstrated difficulty of measuring and extracting the spin structure functions, it appears that there are no easy measurements to investigate the nucleon spin structure save the earlier experiments that fixed the axial vector form factors of well-known baryon decays (neutron, lambda, etc.). With the emergence of the provocative results from the EMC group on the spin structure function of the proton, there has been renewed interest in the information contained in the cross sections for neutral current neutrino-nucleon scattering. The theoretical background for describing this process has been worked out in detail. It is presented in briefest outline below to define the terms needed to describe experimental results
International Nuclear Information System (INIS)
Chiral theories with spontaneous symmetry breaking such as the Nambu-Jona-Lasinio (NJL) model lead to the existence of a scalar mode. We present in a detailed manner how the corresponding low-momentum effective Lagrangian involving the scalar field can be constructed starting from the NJL model. We discuss the relevance of the scalar mode for the problem of nuclear binding and saturation. We show that it depends on the nucleon mass origin with two extreme cases. If this origin is entirely due to confinement, the coupling of this mode to the nucleons vanishes, making it irrelevant for the nuclear binding problem. If instead it is entirely due to spontaneous symmetry breaking, it couples to the nucleons but nuclear matter collapses. It is only in the case of a mixed origin with spontaneous breaking that nuclear matter can be stable and reach saturation. We describe models of nucleon structure where this balance is achieved. We also show how chiral constraints and confinement modify the QCD sum rules for mass evolution in nuclear matter.
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.)
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
Kaiser, N
2012-01-01
A recent calculation of the nuclear energy density functional from chiral two- and three-nucleon forces is extended to the isovector terms pertaining to different proton and neutron densities. An improved density-matrix expansion is adapted to the situation of small isospin-asymmetries and used to calculate in the Hartree-Fock approximation the density-dependent strength functions associated with the isovector terms. The two-body interaction comprises of long-range multi-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition, the leading order chiral three-nucleon interaction is employed with its parameters fixed in computations of nuclear few-body systems. With this input one finds for the asymmetry energy of nuclear matter the value $A(\\rho_0) \\simeq 26.5\\,$MeV, compatible with existing semi-empirical determinations. The strength functions of the isovector surface and spin-orbit coupling terms come out much smaller than those of the analogous isoscalar...
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
International Nuclear Information System (INIS)
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from 1?-exchange, iterated 1?-exchange, and irreducible 2?-exchange with intermediate ?-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass M*(?) entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength F?(?) of the (???)2 surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region ?0/20. The spin-orbit coupling strength Fso(?) receives contributions from iterated 1?-exchange (of the 'wrong sign') and from three-nucleon interactions mediated by 2?-exchange with virtual ?-excitation (of the 'correct sign'). In the region around ?0/2?0.08 fm-3 where the spin-orbit interaction in nuclei gains most of its weight these two components tend to cancel, thus leaving all room for the short-range spin-orbit interaction. The strength function FJ(?) multiplying the square of the spin-orbit density comes out much larger than in phenomenological Skyrme forces and it has a pronounced density dependeed density dependence.
Mathematics for structure functions
Vermaseren, J. A. M.; Moch, S.
2000-01-01
We show some of the mathematics that is being developed for the computation of deep inelastic structure functions to three loops. These include harmonic sums, harmonic polylogarithms and a class of difference equations that can be solved with the use of harmonic sums.
Structure and direct nucleon decay properties of isoscalar giant monopole and dipole resonances
Energy Technology Data Exchange (ETDEWEB)
Gorelik, M. L.; Shlomo, S.; Urin, M. H.
2000-10-01
The strength function and partial widths for the direct nucleon decay of the isoscalar giant monopole and dipole resonances are analyzed within an extended continuum-random-phase-approximation approach. Calculations are performed for several medium and heavy mass nuclei with the use of a phenomenological nuclear mean field, the Landau-Migdal particle-hole interaction, and some partial self-consistency conditions. Calculation results are compared with available experimental data.
Studies of partonic transverse momentum and spin structure of the nucleon
Directory of Open Access Journals (Sweden)
Contalbrigo M.
2014-06-01
Full Text Available The investigation of the partonic degrees of freedom beyond collinear approximation (3D description has been gained increasing interest in the last decade. The Thomas Jefferson National Laboratory, after the CEBAF upgrade to 12 GeV, will become the most complete facility for the investigation of the hadron structure in the valence region by scattering of polarized electron off various polarized nucleon targets. A compendium of the planned experiments is here presented.
Progress in resolving charge symmetry violation in nucleon structure
Young, R D; Thomas, A W
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.
Unified approach to structure factors and neutrino processes in nucleon matter
International Nuclear Information System (INIS)
We present a unified approach to neutrino processes in nucleon matter based on Landau's theory of Fermi liquids that includes one and two quasiparticle-quasihole pair states as well as mean-field effects. We show how rates of neutrino processes involving two nucleons may be calculated in terms of the collision integral in the Landau transport equation for quasiparticles. Using a relaxation time approximation, we solve the transport equation for density and spin-density fluctuations and derive a general form for the response functions. We apply our approach to neutral-current processes in neutron matter, where the spin response function is crucial to the calculation of neutrino elastic and inelastic scattering and neutrino-pair bremsstrahlung and absorption from strongly interacting nucleons. We calculate the relaxation rates using modern nuclear interactions and including many-body contributions, and find that rates of neutrino processes are reduced compared with estimates based on the one-pion exchange interaction, which is used in current simulations of core-collapse supernovae
EM vs Weak Structure Functions in DIS processes
Athar, M Sajjad; Simo, I Ruiz; Vacas, M J Vicente
2013-01-01
We obatin the ratio $F_i^A/F_i^{D}$(i=2,3, A=Be, C, Fe, Pb; D=Deuteron) in the case of weak and electromagnetic nuclear structure functions. For this, relativistic nuclear spectral function which incorporate the effects of Fermi motion, binding and nucleon correlations is used. We also consider the pion and rho meson cloud contributions and shadowing and antishadowing effects.
Structure functions in ? decays
International Nuclear Information System (INIS)
Semileptonic decays of polarized ? leptons are investigated and the most general angular distribution of two and three meson final states is derived. Emphasis is put on ? studies in electron positron annihilation where the neutrino escapes detection and the ? restframe cannot be reconstructed. It is shown that the most general distribution caan be characterized by 16 structure functions, most of which can be determined in currently ongoing high statistics experiments. Of particular interest for the three meson case are the distribution of the normal to the Dalitz plane and the distribution around this normal. Predictions for the structure functions are given for the two and three pion case and for K*(?K?). Implications for an experiment where the ? restframe could be reconstructed are also considered. (orig.)
Isovector magnetic structure of the two- and three-nucleon systems
International Nuclear Information System (INIS)
The backward cross section for electrodisintegration of 2H near threshold and the magnetic form factors of 3H and 3He are found to be in fair agreement with empirical values up to momentum transfers about 1 GeV/c, when calculated with the Argonne two-nucleon and Urbana model-VII three-nucleon interactions, exact (A=2) and variational or 34-channel Faddeev (A=3) wave functions, and a realistic current operator constructed from the Argonne ?14 potential model. Below 1 GeV/c the exchange current contribution increases and above 1 GeV/c it strongly decreases the calculated electrodisintegration cross section. Second zeroes are predicted for the magnetic form factors of 3H and 3He at about 1.4 GeV/c. (orig.)
Transverse spin structure of the nucleon from lattice-QCD simulations.
Göckeler, M; Hägler, Ph; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schäfer, A; Schierholz, G; Stüben, H; Zanotti, J M
2007-06-01
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, 094020 (2005)], we predict that the Boer-Mulders function h(1/1), describing correlations of transverse quark spin and intrinsic transverse momentum of quarks, is large and negative for both up and down quarks. PMID:17677836
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.
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
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
Kaiser, N.; Weise, W.
2010-05-01
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from 1 ?-exchange, iterated 1 ?-exchange, and irreducible 2 ?-exchange with intermediate ?-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass M(?) entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength F(?) of the ( surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region ?/2Skyrme forces and it has a pronounced density dependence.
Nuclear structure functions at low-x in a holographic approach
International Nuclear Information System (INIS)
Nuclear effects in deep inelastic scattering at low x are phenomenologically described changing the typical dynamical and/or kinematical scales characterizing the free nucleon case. In a holographic approach, this rescaling is an analytical property of the computed structure function F2(x, Q2). This function is given by the sum of a conformal term and of a contribution due to quark confinement, depending on IR hard-wall parameter z0 and on the mean square distances, related to a parameter Q', among quarks and gluons in the target. The holographic structure function per nucleon in a nucleus A is evaluated showing that a rescaling of the typical nucleon size, z0 and Q', due to nuclear binding, can be reabsorbed in a Q2-rescaling scheme. The difference between neutron and proton structure functions and the effects of the longitudinal structure functions can also be taken into account. The obtained theoretical results favorably compare with the experimental data. (orig.)
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
Energy Technology Data Exchange (ETDEWEB)
Kaiser, N. [Physik Department, Technische Universitaet Muenchen, D-85747 Garching (Germany)], E-mail: nkaiser@ph.tum.de; Weise, W. [Physik Department, Technische Universitaet Muenchen, D-85747 Garching (Germany)
2010-05-15
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from 1{pi}-exchange, iterated 1{pi}-exchange, and irreducible 2{pi}-exchange with intermediate {delta}-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass M{sup *}({rho}) entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength F{sub {nabla}}({rho}) of the ({nabla}{sup {yields}}{rho}){sup 2} surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region {rho}{sub 0}/2<{rho}<{rho}{sub 0}. The spin-orbit coupling strength F{sub so}({rho}) receives contributions from iterated 1{pi}-exchange (of the 'wrong sign') and from three-nucleon interactions mediated by 2{pi}-exchange with virtual {delta}-excitation (of the 'correct sign'). In the region around {rho}{sub 0}/2{approx_equal}0.08 fm{sup -3} where the spin-orbit interaction in nuclei gains most of its weight these two components tend to cancel, thus leaving all room for the short-range spin-orbit interaction. The strength function F{sub J}({rho}) multiplying the square of the spin-orbit density comes out much larger than in phenomenological Skyrme forces and it has a pronounced density dependence.
Cao, X G; Ma, Y G; Fang, D Q; Zhang, G Q; Guo, W; Chen, J G; Wang, J S; 10.1103/PhysRevC.86.044620
2012-01-01
Proton-neutron, neutron-neutron and proton-proton momentum correlation functions ($C_{pn}$, $C_{nn}$, $C_{pp}$) are systematically investigated for $^{15}$C and other C isotopes induced collisions at different entrance channel conditions within the framework of the isospin-dependent quantum molecular dynamics (IDQMD) model complemented by the CRAB (correlation after burner) computation code. $^{15}$C is a prime exotic nucleus candidate due to the weakly bound valence neutron coupling with closed-neutron shell nucleus $^{14}$C. In order to study density dependence of correlation function by removing the isospin effect, the initialized $^{15}$C projectiles are sampled from two kinds of density distribution from RMF model, in which the valence neutron of $^{15}$C is populated on both 1$d$5/2 and 2$s$1/2 states, respectively. The results show that the density distributions of valence neutron significantly influence nucleon-nucleon momentum correlation function at large impact parameter and high incident energy. T...
Parkin structure and function.
Seirafi, Marjan; Kozlov, Guennadi; Gehring, Kalle
2015-06-01
Mutations in the parkin or PINK1 genes are the leading cause of the autosomal recessive form of Parkinson's disease. The gene products, the E3 ubiquitin ligase parkin and the serine/threonine kinase PINK1, are neuroprotective proteins, which act together in a mitochondrial quality control pathway. Here, we review the structure of parkin and mechanisms of its autoinhibition and function as a ubiquitin ligase. We present a model for the recruitment and activation of parkin as a key regulatory step in the clearance of depolarized or damaged mitochondria by autophagy (mitophagy). We conclude with a brief overview of other functions of parkin and considerations for drug discovery in the mitochondrial quality control pathway. PMID:25712550
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
Monte Carlo Generators for Studies of the 3D Structure of the Nucleon
Avakian, Harut
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 e?ects, and allowing control of systematic uncertainties due to variations of input parameters and models. Development of realistic Monte-Carlo generators, accounting for TMD evolution effects, spin-orbit and quark-gluon correlations will be crucial for future studies of quark-gluon dynamics in general and 3D structure of the nucleon in particular.
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.
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.
Chang, Wen-Chen
2015-01-01
The observation of the violation of Lam-Tung relation in the $\\pi N$ Drell-Yan process triggered many theoretical speculations. The TMD Boer-Mulders functions characterizing the correlation of transverse momentum and transverse spin for partons in unpolarized hadrons could nicely account for the violation. The COMPASS experiment at CERN will measure the angular distributions of dimuons from the unpolarized Drell-Yan process over a wide kinematic region and study the beam particle dependence. Significant statistics is expected from a successful run in 2015 which will bring further understanding of the origin of the violation of Lam-Tung relation and of the partonic transverse spin structure of the nucleon.
Radici, Marco
2014-07-01
Starting from the interpretation of the nucleon electromagnetic form factors in terms of charge/magnetic density, we illustrate the need and the advantages of a multidimensional exploration of the structure of the nucleon, and in general of hadrons. We introduce new tools, like the Generalized Parton Distributions (GPDs) and the Transverse Momentum Distributions (TMDs), which enable us to explore the dynamics of partons beyond the usual collinear approximation adopted in the QCD analysis of hard processes. We emphasize the possibility of using these tools to address the (orbital) angular momentum of partons, and we highlight the latest results on the partonic decomposition of the nucleon spin. We briefly touch on the possible breaking of universality for a specific category of TMDs; as an example, we describe the Sivers effect as a fundamental test of our understanding of the color force in QCD.
Gebremariam, B.; Bogner, S. K.; Duguet, T
2010-01-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam {\\it et al.} to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (...
DEFF Research Database (Denmark)
Sinden, Richard R.; E. Pearson, Christopher
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 drive. The structure of the DNA described by Watson and Crick in 1953 is a right handed helix of two individual antiparallel DNA strands. Hydrogen bonds provide specificity that allows pairing between the complementary bases (A.T and G.C) in opposite strands. Base stacking occurs near the center of the DNA helix and provides a great deal of stability to the helix (in addition to hydrogen bonding). The sugar and phosphate groups form a “backbone” on the outside of the helix. There are about 10 base pairs (bp) per turn ofthe double helix.
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?
Nefkens, B. M. K.
1998-05-01
MENU'97 covered many stunning successes of chiral symmetry in intermediate energy reactions, especially of processes that involve pions. These successes include coupling constants, scattering lengths, threshold meson production, electric and magnetic polarizabilities of pions and nucleons, peripheral NN scattering, ?, ? and K decay rates and spectra. The ?N data bank at low energy, which in the past was notorious for the inconsistencies of different data sets, is shown to become consistent by deleting a modest number of previously accepted data sub-sets. There is a consensus on a better value for the pion-nucleon coupling constant, which has been a bone of contention earlier, namely, f?NN2/4?=(75.4±0.4)×10-3 in satisfactory agreement with the Goldberger-Treiman relation. The mass-spin/parity distribution of the experimentally established ?N resonances does not support the prediction of the harmonic oscillator type quark model. Some massive ?++ resonances decay by ? emission to the ?+p? final state. In contrast to this the decay of massive N* states to ?-p? in small, less than 5% of ?++??+p?. A new s-wave ? decay has been identified, D33(1700)?P33(1232)+?. There is interesting new threshold data from CELSIUS on np?d? as well as on pp?pp? and np?np?.
Nuclear structure functions in carbon near x=1
International Nuclear Information System (INIS)
Data from deep inelastic scattering of 200 GeV muons on a carbon target with squared four-momentum transfer 52 GeV2?Q2?200 GeV2 were analysed in the region of the Bjorken variable close to x=1, which is the kinematic limit for scattering on a free nucleon. At this value of x, the carbon structure function is found to be F2C?1.2.10-4. The x dependence of the structure function for x>0.8 is well described by an exponential F2C?exp(-sx) with s=16.5±0.6. (orig.)
Nucleon quark distributions in a covariant quark-diquark model
Cloet, I. C.; Bentz, W.; Thomas, A. W.
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.(Jefferson Lab, Newport News, VA 23606, USA); Saito, K.(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan); 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 ...
Nucleon color oscillations in nuclei and the EMC-effect
International Nuclear Information System (INIS)
The problem of the EMC-effect is discussed. It is shown that the existence of long-range six-quark clusters in nuclei allows to understand why the nucleon structure function in a nucleus differs from that of a free nucleon
Gauge invariance, Lorentz covariance and canonical quantization in nucleon structure studies
Wang, Fan; Sun, W M; Zhang, P M; Wong, C W
2014-01-01
There are different operators of quark and gluon momenta, orbital angular momenta, and gluon spin in the nucleon structure study. The precise meaning of these operators are studied based on gauge invariance, Lorentz covariance and canonical quantization rule. The advantage and disadvantage of different definitions are analyzed. A gauge invariant canonical decomposition of the total momentum and angular momentum into quark and gluon parts is suggested based on the decomposition of the gauge potential into gauge invariant (covariant) physical part and gauge dependent pure gauge part. Challenges to this proposal are answered. \\keywords{Physical and pure gauge potentials; Gauge invariant canonical quark and gluon momenta, orbital angular momenta and spins; Homogeneous and non-homogeneous Lorentz transformations; Gauge invariant decomposition and gauge invariant extension; Classical and quantum measurements.
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
New measurements of high-momentum nucleons and short-range structures in nuclei
Fomin, N; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Bukhari, M H S; Chudakov, E; Clasie, B; Connell, S H; Dalton, M M; Daniel, A; Day, D B; Dutta, D; Ent, R; Fassi, L El; Fenker, H; Filippone, B W; Garrow, K; Gaskell, D; Hill, C; Holt, R J; Horn, T; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, M; Lindgren, R; Lung, A F; Malace, S; Markowitz, P; McKee, P; Meekins, D G; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Seely, J; Segbefia, E; Slifer, K; Smith, G R; Solvignon, P; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Trojer, R; Tvaskis, V; Vulcan, W F; Wasko, C; Wesselmann, F R; Wood, S A; Wright, J; Zheng, X
2011-01-01
We present new, high-Q^2 measurements of inclusive electron scattering from high-momentum nucleons in nuclei. This yields an improved extraction of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data extend to the kinematic regime where three-nucleon correlations are expected to dominate and we observe significantly greater strength in this region than previous measurements.
Renal Structure & Function Activities
Ms. Terry Thompson (Wor-Wic Community College Math/Science)
2007-07-31
This activity includes three sequential classroom activities for pairs of students using worksheets. This includes removeable stickers sequencing kinesthetic activity, diagram coloring and table matching to correlate nephron and cell-level anatomical features with physiological function.
Tensor-polarized structure functions: Tensor structure of deuteron in 2020's
Kumano, S
2014-01-01
We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones ($F_1$, $F_2$, $g_1$, $g_2$) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are $b_1$, $b_2$, $b_3$, and $b_4$ 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 $b_2 = 2 x b_1$ in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of $b_{1-4}$ from a hadron tensor $W_{\\mu\
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
Treatment of Two Nucleons in Three Dimensions
Directory of Open Access Journals (Sweden)
Glöckle W.
2010-04-01
Full Text Available We extend a new treatment proposed for two-nucleon (2N and three-nucleon (3N bound states to 2N scattering. This technique takes momentum vectors as variables, thus, avoiding partial wave decomposition, and handles spin operators analytically. We apply the general operator structure of a nucleon-nucleon (NN potential to the NN T-matrix, which becomes a sum of six terms, each term being scalar products of spin operators and momentum vectors multiplied with scalar functions of vector momenta. Inserting this expansions of the NN force and T-matrix into the Lippmann-Schwinger equation allows to remove the spin dependence by taking traces and yields a set of six coupled equations for the scalar functions found in the expansion of the T-matrix.
The nucleon-nucleon interaction
Scientific Electronic Library Online (English)
J., Haidenbauer.
2004-09-01
Full Text Available Recent developements in our understanding of the fundamental nucleon-nucleon interaction are reviewed. Among the topics considered are (1) the so-called high-precision nucleon-nucleon potentials that emerged in the mid 1990s, (2) progress in the microscopic description of the intermediate-range part [...] of the nucleon-nucleon interaction in terms of correlated pion-pion and rho-pion exchange and (3) efforts towards a quantitative descripton of the nucleon-nucleon interaction utilizing methods based on effective field theory.
Problems related to gauge invariance and momentum, spin decomposition in nucleon structure study
Wang, Fan; Sun, W. M.; Chen, X. S.; Zhang, P. M.
2014-07-01
How do the quark and gluon share the nucleon momentum? How does the nucleon spin distribute among its constituents? What means the quark and gluon momentum, spin and orbital angular momentum? These problems are analyzed and a solution is proposed based on gauge invariance principle, canonical quantization rule and Poincaré covariance.
Nucleon structure at Jefferson Lab: from two dimensions to three dimensions
International Nuclear Information System (INIS)
We review very briefly a few recent highlight results from Jefferson Lab concerning nucleon Form Factors and Generalized Parton Distributions for which data with unprecedented precision and phase space coverage have be obtained these past few years. Along with new theoretical developements, these data allow to make some nucleon imaging in terms of partonic degrees of freedom in both momentum and space dimensions.
The structure functions in deep-inelastic semi-inclusive process
International Nuclear Information System (INIS)
Deep-elastic lepton-hadron scattering provides one of the cleanest ways for investigate the nucleon structure at short distances. The spin structure of nucleons can be studied with using both polarized leptons and targets. The semi-inclusive processes of the type l±+N?(?, Z0)? l±+h+X( l±=el±, ?l± were considered, where N is nucleon target with mass M, momentum P, longitudinal polarization SL, h is hadron with mass m and momentum ph detected in coincidence with scattered lepton. The hadronic tensor is constructed requiring Lorentz and time - reversal invariance. The general structure of hadronic tensor is given. Taking into account hard sub processes in perturbative QCD, calculation of hadronic structure functions was carried out
Radioprotectors: structure and function
International Nuclear Information System (INIS)
Research of means of pharmacological protection of the organism against ionizing radiation effect is presented. A modern state of the problem is shown. Non-routine classification of the radioprotectors is given. A connection between chemical structure of the preparations and their antiactinic efficiency is analyzed on the example of many radioprotectors. Some aspects of mechanism of action of various radioprotective substances are studied. The certain chapter is devoted to the problem of preparation of antiactinic compositions. 336 refs.; 29 figs.; 43 tabs
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...
Directory of Open Access Journals (Sweden)
F Zolfagharpour
2012-03-01
Full Text Available In this paper, we calculate nuclear structure function and EMC effect of 40Ca and 56Fe nuclei. To achive the goals, we consider Fermi motion and binding energy contrbiution in the harmonic oscillator model. In this model, harmonic oscillator parameter ?? related to shells root mean square radius and for free nucleon structure functions, is obtained from GRV’s free nucleon structure functions. Then, we calculate differential cross section of lepton scattering from those nuclei at the E=4.8 GeV and E=4.032 GeV. The obtained results show good agreement with available experimental data.
Formation of a necklike structure in 35Cl+12C and 197Au reactions at 43 MeV/nucleon
International Nuclear Information System (INIS)
The experimental signature of the formation of a necklike structure, with a velocity between that of the projectilelike emitter and that of the targetlike emitter, is investigated with the same beam and experimental setup for targets lighter and heavier than the projectile. The reactions are 35Cl on 12C and on 197Au at 43 MeV/nucleon. Particle velocity distributions are compared with two-source statistical simulations and the presence of a necklike structure is inferred from the data. In the second part of the paper, dynamical model simulations with the formation of a necklike structure are presented for the 35Cl+12C system at 43 MeV/nucleon. copyright 1997 The American Physical Society
Formation of a necklike structure in 35Cl+12C and 197Au reactions at 43 MeV/nucleon
Larochelle, Y.; Gingras, L.; Beaulieu, L.; Qian, X.; Saddiki, Z.; Djerroud, B.; Doré, D.; Laforest, R.; Roy, R.; Samri, M.; St-Pierre, C.; Ball, G. C.; Bowman, D. R.; Galindo-Uribarri, A.; Hagberg, E.; Horn, D.; López, J. A.; Robinson, T.
1997-04-01
The experimental signature of the formation of a necklike structure, with a velocity between that of the projectilelike emitter and that of the targetlike emitter, is investigated with the same beam and experimental setup for targets lighter and heavier than the projectile. The reactions are 35Cl on 12C and on 197Au at 43 MeV/nucleon. Particle velocity distributions are compared with two-source statistical simulations and the presence of a necklike structure is inferred from the data. In the second part of the paper, dynamical model simulations with the formation of a necklike structure are presented for the 35Cl+12C system at 43 MeV/nucleon.
Spin-orbit coupling in nuclei and realistic nucleon-nucleon potentials
Kaiser, N.
2004-01-01
We analyze the spin-orbit coupling term in the nuclear energy density functional in terms of a zero-range NN-contact interaction and finite-range contributions from two-pion exchange. We show that the strength of the spin-orbit contact interaction as extracted from high-precision nucleon-nucleon potentials is in perfect agreement with that of phenomenological Skyrme forces employed in non-relativistic nuclear structure calculations. Additional long-range contributions from c...
International Nuclear Information System (INIS)
We describe the technique and present the results of a study of the reaction 3He (e,e'p) for primary energies E/sub i/ = 806 and 643 MeV and electron scattering angles theta/sub e/ = 31 and 280 with energy resolution 4 and 2.6 MeV, respectively. The angular distributions (theta/sub p/ = 47.5--72.50 and 54--720) and momentum distributions (q/sub R/ = +- 100 MeV/c) of protons for two-particle and three-particle disintegration of 3He are compared with model and exact calculations with use of various wave functions of the 3He ground state. It is shown that the angular and momentum distributions obtained are best described by a model calculation with use of the Irving wave function and the exact calculation with the Yamaguchi potential and the Tabakin parameters
SYSTEMS THEORY AND STRUCTURAL FUNCTIONALISM
Directory of Open Access Journals (Sweden)
Shrikant Yelegaonkar
2014-12-01
Full Text Available Albeit structural functionalism thinks that its roots much sooner than frameworks does hypothesis, as analysts utilization it today, it is focused around frameworks hypothesis. Structural functionalism follows its beginnings back to the aged Greeks and the compositions of Aristotle (Susser, 1992. Frameworks hypothesis rose much later. Despite the fact that the discourse of frameworks started with scientists in the nineteenth century, frameworks hypothesis was not completely verbalized until the 1920s. Ludwig von Bertalanffy (1956, 1962, who created general frameworks hypothesis, was a primary in making it as a field of study. In spite of the fact that frameworks hypothesis began later than functionalism, when scientists study works inside their structures, they do it inside the extent of frameworks. The investigation of political frameworks contributed more than its fair share with the selection of a structural- utilitarian methodology
Functional Insights from Structural Genomics
Energy Technology Data Exchange (ETDEWEB)
Forouhar,F.; Kuzin, A.; Seetharaman, J.; Lee, I.; Zhou, W.; Abashidze, M.; Chen, Y.; Montelione, G.; Tong, L.; et al
2007-01-01
Structural genomics efforts have produced structural information, either directly or by modeling, for thousands of proteins over the past few years. While many of these proteins have known functions, a large percentage of them have not been characterized at the functional level. The structural information has provided valuable functional insights on some of these proteins, through careful structural analyses, serendipity, and structure-guided functional screening. Some of the success stories based on structures solved at the Northeast Structural Genomics Consortium (NESG) are reported here. These include a novel methyl salicylate esterase with important role in plant innate immunity, a novel RNA methyltransferase (H. influenzae yggJ (HI0303)), a novel spermidine/spermine N-acetyltransferase (B. subtilis PaiA), a novel methyltransferase or AdoMet binding protein (A. fulgidus AF{_}0241), an ATP:cob(I)alamin adenosyltransferase (B. subtilis YvqK), a novel carboxysome pore (E. coli EutN), a proline racemase homolog with a disrupted active site (B. melitensis BME11586), an FMN-dependent enzyme (S. pneumoniae SP{_}1951), and a 12-stranded {beta}-barrel with a novel fold (V. parahaemolyticus VPA1032).
Light-front quark distributions in the nucleon and nucleon electromagnetic form factors
Pace, E.; Melo, J. P. B. C.; Frederico, T.; Pisano, S.; Salme, G.
2010-01-01
Longitudinal and transverse quark momentum distributions in the nucleon are calculated from a phenomenological quark-nucleon vertex function obtained through an investigation of the nucleon electromagnetic form factors within a light-front framework.
Spatial Variation of Nuclear Structure Functions and Heavy Quark Production
Emelyanov, V I; Klein, S R; Vogt, R
1998-01-01
We explore how nuclear modifications to the free nucleon structure functions (also known as shadowing) affect heavy quark production in collisions at different impact parameters. We assume that the nuclear modifications arise from a density dependent effect such as gluon recombination and are thus proportional to the local density. We calculate the dependence of charm and bottom quark production on impact parameter and show that density dependent modifications can lead to significant reductions in the heavy quark production cross sections in central relative to peripheral interactions.
Bound Nucleon Form Factors, Quark-Hadron Duality, and the Nuclear EMC Effect
International Nuclear Information System (INIS)
We discuss the electromagnetic form factors, axial form factors, and structure functions of a nucleon bound 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 (EMC) model, the in-medium modification of the bound nucleon form factors is calculated in the same model. Finally, the bound nucleon structure function, F2, is extracted using the calculated in-medium electromagnetic form factors and Bloom-Gilman (quark-hadron) duality
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.
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
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 eparation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor
Nuclear structure functions in the boundary region of the single-particle kinematics
International Nuclear Information System (INIS)
A theoretical analysis of nuclear functions in the region x?1 is given. It is shown that the contributions of pure nucleons and multiquak components of the nuclear wave function in this region are comparable and the binding effects and Q2-evolution lead to softening of the quark distributions in nucleus. Numerical predictions for the carbon structure function in the cumulative region were made
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.
Chiral three-nucleon interactions in ab-initio nuclear structure and reactions
Energy Technology Data Exchange (ETDEWEB)
Langhammer, Joachim
2014-04-23
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 {sup 12}C and {sup 10}B 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-{sup 4}He 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-{sup 8}Be system to study the impact of the continuum on the {sup 9}Be energy levels. The results demonstrate the importance of the consistent treatment of continuum states.
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
Measurement of the interference stucture function chiG3(chi) in muon-nucleon scattering
International Nuclear Information System (INIS)
The interference structure function chiG3(chi) has been measured for the first time scattering positive and negative muons of opposite helicity off a carbon target. The chi dependence observed for Q2 between 40 and 180 (GeV/c2) is in good agreement with predictions of the quark-parton model. The measured ratio 2(asub(u)Qsub(u) + asub(d)Qsub(d))/(Qsub(u)2+Qsub(d)2)=1.87 +- 0.25 (stat.) +- 0.24 (syst.) is consistent with the hypothesis of fractional quark charges and determines the sign of Qsub(u)-Qsub(d) to be positive. (orig.)
On the unabridged 7D-folding structure of the optical model potential for nucleon-nucleus scattering
Directory of Open Access Journals (Sweden)
Bauge E.
2012-02-01
Full Text Available Microscopic optical model potentials for nucleon-nucleus collisions, based on density-dependent effective interactions, involve multi-dimensional integrals to account for the Fermi motion of the bound nucleons of the target. If a spherical matter distribution is assumed, each matrix element of the optical potential in momentum space requires the evaluation of seven-dimensional integrals. Here we describe the structure of these potentials and report results from their actual evaluation. Results for the scattering observables are compared with those based on alternative approximations, observing moderate sensitivity. These findings validate the use of simpler expressions to evaluate folding optical potentials, from which higher-order or unconventional effects in the effective interaction can safely be investigated.
Nucleon and pion structure with lattice QCD simulations at physical value of the pion mass
Abdel-Rehim, A; Constantinou, M; Dimopoulos, P; Frezzotti, R; Hadjiyiannakou, K; Jansen, K; Kallidonis, Ch; Kostrzewa, B; Koutsou, G; Mangin-Brinet, M; Oehm, M; Rossi, G C; Urbach, C; Wenger, U
2015-01-01
We present results on the nucleon scalar, axial and tensor charges as well as on the momentum fraction, and the helicity and transversity moments. The pion momentum fraction is also presented. The computation of these key observables is carried out using lattice QCD simulations at a physical value of the pion mass. The evaluation is based on gauge configurations generated with two degenerate sea quarks of twisted mass fermions with a clover term. We investigate excited states contributions with the nucleon quantum numbers by analyzing three sink-source time separations. We find that, for the scalar charge, excited states contribute significantly and to a less degree to the nucleon momentum fraction and helicity moment. Our analysis yields a value for the nucleon axial charge agrees with the experimental value and we predict a value of 1.027(62) in the $\\overline{\\text{MS}}$ scheme at 2 GeV for the isovector nucleon tensor charge directly at the physical point. The pion momentum fraction is found to be $\\langl...
FERMILAB: structure function of pions
International Nuclear Information System (INIS)
Recent experimental results for the structure function of pions are reported. The difference in the effectiveness of pion and proton beams in producing muon pairs off nuclear targets is in good agreement with the quark model of hadrons. (W.D.L.).
The dipole model structure functions
International Nuclear Information System (INIS)
We present an approach to the evolution of the valence structure functions based on the Colour Dipole Cascade Model for deep inelastic lepto-production. We show that this approach leads to an evolution equation similar to the DGLAP equation. In our approach the dependence on Q2 is however much weaker and the evolution levels out at high Q2. (orig.)
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.
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.)
Electromagnetic Structure and Reactions of Few-Nucleon Systems in $\\chi$EFT
Girlanda, L; Schiavilla, R; 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 thermal neutron captures on $p$, $d$, and $^3$He.
Electromagnetic Structure and Reactions of Few-Nucleon Systems in ?EFT
Directory of Open Access Journals (Sweden)
Schiavilla R.
2010-04-01
Full Text Available We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral e?ective ?eld theory (?EFT. The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and thermal neutron captures on p, d, and 3He.
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
x- and xi-scaling of the Nuclear Structure Function at Large x
International Nuclear Information System (INIS)
Inclusive electron scattering data are presented for 2H and Fe targets at an incident electron energy of 4.045 GeV for a range of momentum transfers from Q2 = 1 to 7 (GeV/c)2. Data were taken at Jefferson Laboratory for low values of energy loss, corresponding to values of Bjorken x greater than or near 1. The structure functions do not show scaling in x in this range, where inelastic scattering is not expected to dominate the cross section. The data do show scaling, however, in the Nachtmann variable ?. This scaling may be the result of Bloom Gilman duality in the nucleon structure function combined with the Fermi motion of the nucleons in the nucleus. The resulting extension of scaling to larger values of ? opens up the possibility of accessing nuclear structure functions in the high-x region at lower values of Q2 than previously believed
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 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. (orig.)
Chiral perturbation theory with nucleons
International Nuclear Information System (INIS)
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, ?N scattering and the ?-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon
Cell Structure and Function Lessons
Ingrid Waldron
This overview presents key concepts that students often do not learn from standard textbook presentations and suggests a sequence of learning activities to help students understand how the parts of a cell work together to accomplish the multiple functions of a dynamic living cell. Suggested activities also reinforce student understanding of the relationships between molecules, organelles and cells, the diversity of cell structure and function, and the importance and limitations of diffusion. This overview provides links to Web resources, hands-on activities and discussion activities.
Hadron structure function in flux tube model
International Nuclear Information System (INIS)
The quark distribution functions of the meson (q-(q-bar) system) and the nucleon (both q-diquark system and symmetric Y shape system) are calculated using the yo-yo mode of the classical string model. The valence quark distributions of the proton are consistent with intermediate value of q-diquark and symmetric Y shape calculation. Using the Weizsaecker-Williams approximation, the gluon distribution function is obtained from the Poynting vector of the flux tube which has the same energy-momentum relation as the string. (author)
Nuclear energy density functional from chiral pion-nucleon dynamics: Isovector terms
Energy Technology Data Exchange (ETDEWEB)
Kaiser, N. [Technische Universitaet Muenchen, Physik Department T39, Garching (Germany)
2010-07-15
We extend a recent calculation of the nuclear energy density functional in the framework of chiral perturbation theory by computing the isovector surface and spin-orbit terms: (vector {nabla}{rho}{sub p}-vector {nabla}{rho}{sub n}){sup 2} G{sub d}({rho})+(vector {nabla}{rho}{sub p}-vector {nabla}{rho}{sub n}).(vector J{sub p}-vector J{sub n})G{sub so}({rho})+(vector J{sub p}-vector J{sub n}){sup 2} G{sub J}({rho}) pertaining to different proton and neutron densities. Our calculation treats systematically the effects from 1 {pi} -exchange, iterated 1 {pi} -exchange, and irreducible 2{pi} -exchange with intermediate {delta} -isobar excitations, including Pauli-blocking corrections up to three-loop order. Using an improved density-matrix expansion, we obtain results for the strength functions G{sub d}({rho}), G{sub so}({rho}) and G{sub J}({rho}) which are considerably larger than those of phenomenological Skyrme forces. These (parameter-free) predictions for the strength of the isovector surface and spin-orbit terms as provided by the long-range pion-exchange dynamics in the nuclear medium should be examined in nuclear structure calculations at large neutron excess. (orig.)
Nuclear energy density functional from chiral pion-nucleon dynamics: Isovector terms
Kaiser, N.
2010-07-01
We extend a recent calculation of the nuclear energy density functional in the framework of chiral perturbation theory by computing the isovector surface and spin-orbit terms: (?c nabla ? _p - ?c nabla ? _n )2 G d( ?) + (?c nabla ? _p - ?c nabla ? _n ·(?c J_p - ?c J_n ) G so( ?) + (?c J_p - ?c J_n )2 G J( ?) pertaining to different proton and neutron densities. Our calculation treats systematically the effects from 1 ? -exchange, iterated 1 ? -exchange, and irreducible 2 ? -exchange with intermediate ? -isobar excitations, including Pauli-blocking corrections up to three-loop order. Using an improved density-matrix expansion, we obtain results for the strength functions G d( ?) , G so( ?) and G J( ?) which are considerably larger than those of phenomenological Skyrme forces. These (parameter-free) predictions for the strength of the isovector surface and spin-orbit terms as provided by the long-range pion-exchange dynamics in the nuclear medium should be examined in nuclear structure calculations at large neutron excess.
How does nuclear Fermi motion modify the gluon structure function and J/?-leptoproduction
International Nuclear Information System (INIS)
The effect of the nuclear Fermi motion on the gluon structure function is calculated. Due to the steep decrease of G(x) with x in the nucleon, the ratio GA(x)/G(x) shows a steep rise already at small values of x?0.5. The consequences of such a modified structure function on the e(?)+A ? e(?)+J/?+X reaction are estimated at large and small lepton energies (E=280 GeV and E=30 GeV). Other effects which may modify the gluon structure function in the nucleus are discussed. (author) 13 refs.; 3 figs
Hidden Color and the $b_1$ structure function of the deuteron
Miller, Gerald A
2014-01-01
The $b_1$ structure function is an observable feature of a spin-1 system sensitive to non-nucleonic components of the target nuclear wave function. A simple model for hidden-color, six-quark configurations is proposed and found to give substantial contributions for values of $ x>0.2$. Good agreement with Hermes data is obtained. Predictions are made for an upcoming JLab experiment.
Excitation function for 4He(?+,pp)2H two-nucleon absorption across the ? resonance
International Nuclear Information System (INIS)
Angular distributions and total cross sections for the 4He(?+,pp)2H reaction have been measured with small relative uncertainties at incident energies of T?+=64, 87, 114, 162, 217, 278, and 327 MeV. The results strongly support the quasideuteron absorption model for pion absorption on two nucleons, which is found to contribute only ?50% to the total absorption cross section near the ? resonance. All essential reaction channels of pion absorption near the ? resonance on heavier nuclei seem to be present in 4He, but not in 3He. Any nuclear-density-related increase of pion absorption in 4He relative to 2H is <50% and no binding energy effect is found
First moment of the flavour octet nucleon parton distribution function using lattice QCD
Alexandrou, C; Dinter, S; Drach, V; Hadjiyiannakou, K; Jansen, K; Koutsou, G; Vaquero, A
2015-01-01
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, $\\la x\\ra^{(8)} _{\\mu^2 = 4~\\gev^2 }$. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed in \\cite{Dinter:2012tt}. We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio $\\frac{\\la x \\ra^{(3)}}{\\la x \\ra^{(8)}}$ (with $\\la x \\ra^{(3)}$ the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, $\\frac{\\la x \\ra^{(3)}}{\\la x \\ra^{(8)}} = 0.39(1)(4)$.
Functional nanometer-scale structures
Chan, Tsz On Mario
Nanometer-scale structures have properties that are fundamentally different from their bulk counterparts. Much research effort has been devoted in the past decades to explore new fabrication techniques, model the physical properties of these structures, and construct functional devices. The ability to manipulate and control the structure of matter at the nanoscale has made many new classes of materials available for the study of fundamental physical processes and potential applications. The interplay between fabrication techniques and physical understanding of the nanostructures and processes has revolutionized the physical and material sciences, providing far superior properties in materials for novel applications that benefit society. This thesis consists of two major aspects of my graduate research in nano-scale materials. In the first part (Chapters 3--6), a comprehensive study on the nanostructures based on electrospinning and thermal treatment is presented. Electrospinning is a well-established method for producing high-aspect-ratio fibrous structures, with fiber diameter ranging from 1 nm--1 microm. A polymeric solution is typically used as a precursor in electrospinning. In our study, the functionality of the nanostructure relies on both the nanostructure and material constituents. Metallic ions containing precursors were added to the polymeric precursor following a sol-gel process to prepare the solution suitable for electrospinning. A typical electrospinning process produces as-spun fibers containing both polymer and metallic salt precursors. Subsequent thermal treatments of the as-spun fibers were carried out in various conditions to produce desired structures. In most cases, polymer in the solution and the as-spun fibers acted as a backbone for the structure formation during the subsequent heat treatment, and were thermally removed in the final stage. Polymers were also designed to react with the metallic ion precursors during heat treatment in some cases, which led to desired chemical phase formation. The residue of polymer thermal decomposition was also controlled and utilized for certain functionality in some nanostructures. Throughout this study, we successfully fabricated several novel functional structures and revealed a new formation mechanism of metal/metal oxide nanotubes. The magnetic and electrical properties of these nanostructures were studied and optimized for applications in soft magnetic materials and spintronics devices. In the second part, (Chapter 7) a study on memristive switching devices with magnetron-sputtered metal-semiconductor-metal thin film structures based on ZnO is presented. Resistive random access memory (RRAM) is a new, non-volatile memory based on the memristor effect theoretically predicted by Leon Chua in 1971 and first experimentally demonstrated by Hewlett Packard in 2008. The unit cell of a RRAM (a memristor) is a two-terminal device in which the switching medium is sandwiched between the top and bottom electrodes and the resistance of the switching medium can be modulated by applying an electrical signal (current or voltage) to the electrodes. On the other hand, the significance of a memristor, as the fourth element of circuit elements besides resistor, capacitor and inductor, is not limited to just being a candidate for next-generation memory. Owing to the unique i-v characteristics of non-linear memristors that cannot be duplicated with any combinations of the other three basic elements in a passive circuitry, many new electrical functions are being developed based on the memristors. In our study, various contact electrode combinations and semiconductor doping profiles were utilized to achieve different functional resistive switching behaviors and to help fundamentally understand the underlying switching mechanisms in ZnO-based thin film structures. Two distinctive switching mechanisms (ferroelectric charge-induced resistive switching and dopant-induced filament-type resistive switching) have been identified in specified structures. Among them, the ferroelectric charg
Partons in the chiral periphery of the nucleon
Granados, Carlos G.
2015-04-01
We introduce transverse densities in the study of parton dynamics in the proton's peripheral region. We calculate these densities using chiral perturbation theory (?PT) and parametrize the long distance structure of the nucleon in a model independent framework in which we identify chiral (b ? O(1/M?)) and molecular (b ? O(M2N/(M3?))) parametrical regions. Through the light cone formulation of the nucleon's electromagnetic current in ?PT, one calculates transverse densities from local products of light cone wave functions of a pion- nucleon system. These products are understood as 2-dimensional parton distributions and as such are universal in processes that probe the nucleon's periphery. This universality and also that of the corresponding transverse density can be tested and used in experimental and phenomenological studies of reactions such as high energy proton-nucleon/nucleus collisions and in electron proton scattering as well as in low Q2 extraction of baryonic form factors.
Quark cluster model in the three-nucleon system
International Nuclear Information System (INIS)
The quark cluster model is used to investigate the structure of the three-nucleon systems. The nucleon-nucleon interaction is proposed considering the colour-nucleon clusters and incorporating the quark degrees of freedom. The quark-quark potential in the quark compound bag model agrees with the central force potentials. The confinement potential reduces the short-range repulsion. The colour van der Waals force is determined. Then, the probability of quark clusters in the three-nucleon bound state systems are numerically calculated using realistic nuclear wave functions. The results of the present calculations show that quarks cluster themselves in three-quark systems building the quark cluster model for the trinucleon system. (author)
Serpin structure, function and dysfunction.
Huntington, J A
2011-07-01
Serpins have been studied as a distinct protein superfamily since the early 80s. In spite of the poor sequence homology between family members, serpins share a highly conserved core structure that is critical for their functioning as serine protease inhibitors. Therefore, discoveries made about one serpin can be related to the others. In this short review, I introduce the serpin structure and general mechanism of protease inhibition, and illustrate, using recent crystallographic and biochemical data on antithrombin (AT), how serpin activity can be modulated by cofactors. The ability of the serpins to undergo conformational change is critical for their function, but it also renders them uniquely susceptible to mutations that perturb their folding, leading to deficiency and disease. A recent crystal structure of an AT dimer revealed that serpins can participate in large-scale domain-swaps to form stable polymers, and that such a mechanism may explain the accumulation of misfolded serpins within secretory cells. Serpins play important roles in haemostasis and fibrinolysis, and although each will have some elements specifically tailored for its individual function, the mechanisms described here provide a general conceptual framework. PMID:21781239
Nucleon-nucleon collision profile and cross section fluctuations
Rybczynski, Maciej; Wlodarczyk, Zbigniew
2013-01-01
The nucleon-nucleon collision profile, being the basic entity of the wounded nucleon model, is usually adopted in the form of hard sphere or the Gaussian shape. We suggest that the cross section fluctuations given by the gamma distribution leads to the profile function which smoothly ranges between the both limiting forms. Examples demonstrating sensitivity of profile function on cross section fluctuations are discussed.
Nuclear structure functions at low-x in a holographic approach
Energy Technology Data Exchange (ETDEWEB)
Agozzino, Luca [Universita di Catania, Dipartimento di Fisica, Catania (Italy); INFN, Sezione di Catania, Catania (Italy); Castorina, Paolo [Universita di Catania, Dipartimento di Fisica, Catania (Italy); INFN, Sezione di Catania, Catania (Italy); CERN, PH Department, TH Unit, Geneva 23 (Switzerland); Colangelo, Pietro [INFN, Sezione di Bari, Bari (Italy)
2014-04-15
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 F{sub 2}(x, Q{sup 2}). 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 z{sub 0} and on the mean square distances, related to a parameter Q', among quarks and gluons in the target. The holographic structure function per nucleon in a nucleus A is evaluated showing that a rescaling of the typical nucleon size, z{sub 0} and Q', due to nuclear binding, can be reabsorbed in a Q{sup 2}-rescaling scheme. The difference between neutron and proton structure functions and the effects of the longitudinal structure functions can also be taken into account. The obtained theoretical results favorably compare with the experimental data. (orig.)
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.
Spin and angular momentum in the nucleon
Gross, Franz; Pena, M T
2012-01-01
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.
Energy Technology Data Exchange (ETDEWEB)
D. Day
2007-03-01
The nucleon form factors are still the subject of active investigation even after an experimental effort spanning 50 years. This is because they are of critical importance to our understanding of the electromagnetic properties of nuclei and provide a unique testing ground for QCD motivated models of nucleon structure. Progress in polarized beams, polarized targets and recoil polarimetry have allowed an important and precise set of data to be collected over the last decade. I will review the experimental status of elastic electron scattering from the nucleon along with an outlook for future progress.
Unquenched simulations of four-nucleon interactions
International Nuclear Information System (INIS)
Exploratory simulations of four-nucleon interactions are performed taking into account the dynamical effects of internal nucleon loops. The four-nucleon interactions in the isoscalar and isovector channels are described by Yukawa interactions with auxiliary scalar fields. The nucleon mass and the average field lengths of the scalar fields are determined as a function of nucleon hopping parameter and Yukawa coupling strengths. There are no problems with ''exceptional configurations'' at strong couplings which make quenched simulations unreliable.
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
Parity doubling structure of nucleon at non-zero density in the holographic mean field theory
He, Bing-Ran; Harada, Masayasu
2014-06-01
We summarize our recent work in which we develope the holographic mean field approach to study the dense baryonic matter in a bottom-up holographic QCD model including baryons and scalar mesons in addition to vector mesons. We first show that, at zero density, the rate of the chiral invariant mass of nucleon is controlled by the ratio of the infrared boundary values of two baryon fields included in the model. Then, at non-zero density, we find that the chiral condensate decreases with the increasing density indicating the partial restoration of the chiral symmetry. Our result shows that the more amount of the proton mass comes from the chiral symmetry breaking, the faster the effective nucleon mass decrease with density.
Parity doubling structure of nucleon at non-zero density in the holographic mean field theory
Directory of Open Access Journals (Sweden)
He Bing-Ran
2014-06-01
Full Text Available We summarize our recent work in which we develope the holographic mean field approach to study the dense baryonic matter in a bottom-up holographic QCD model including baryons and scalar mesons in addition to vector mesons. We first show that, at zero density, the rate of the chiral invariant mass of nucleon is controlled by the ratio of the infrared boundary values of two baryon fields included in the model. Then, at non-zero density, we find that the chiral condensate decreases with the increasing density indicating the partial restoration of the chiral symmetry. Our result shows that the more amount of the proton mass comes from the chiral symmetry breaking, the faster the effective nucleon mass decrease with density.
Nucleon form factors, generalized parton distributions and quark angular momentum
Diehl, M.; Desy, Forschung Hochenergiephysik; Kroll, P.
2013-01-01
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 r...
Pasquini, B.; Lorce, C.
2013-01-01
We discuss the general formalism for the calculation in light-front quark models of the fully unintegrated, off-diagonal quark-quark correlator of the nucleon, parametrized in terms of generalized transverse momentum dependent parton distributions (GTMDs). By taking specific limits or projections, these GTMDs yield various transverse-momentum dependent and generalized parton distributions, thus providing a unified framework to simultaneously model different observables. The ...
Nucleon structure with pion mass down to 149 MeV
Green, Jeremy; Krieg, Stefan; Negele, John; Pochinsky, Andrew; Syritsyn, Sergey
2012-01-01
We present isovector nucleon observables: the axial, tensor, and scalar charges and the Dirac radius. Using the BMW clover-improved Wilson action and pion masses as low as 149 MeV, we achieve good control over chiral extrapolation to the physical point. Our analysis is done using three different source-sink separations in order to identify excited-state effects, and we make use of the summation method to reduce their size.
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
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.
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)
Parity doubling structure of nucleon at non-zero density in the holographic mean field theory
He Bing-Ran; Harada Masayasu
2014-01-01
We summarize our recent work in which we develope the holographic mean field approach to study the dense baryonic matter in a bottom-up holographic QCD model including baryons and scalar mesons in addition to vector mesons. We first show that, at zero density, the rate of the chiral invariant mass of nucleon is controlled by the ratio of the infrared boundary values of two baryon fields included in the model. Then, at non-zero density, we find that the chiral condensate decreases with the inc...
Flavor asymmetry of the polarized nucleon sea
Nocera, Emanuele Roberto
2014-01-01
We discuss the flavor asymmetry of polarized light antiquarks in the nucleon, $\\Delta\\bar{u}-\\Delta\\bar{d}$. We present a determination of this quantity based on two global QCD analyses of experimental data, DSSV08 and NNPDFpol1.1, in which sea-quark parton distribution functions are determined respectively either from semi-inclusive deep-inelastic scattering or W-boson production data. The latter have become available only very recently, and their effect on the polarized flavor asymmetry is presented here for the first time. We find that the flavor asymmetry of polarized antiquarks in the nucleon is definitely positive, and has almost the same absolute size as its unpolarized counterpart. We compare this result with various theoretical models of the nucleon structure in order to test their validity. We show that some of them are clearly disfavored.
Systematics of Nuclear Effects in Polarized 3He Structure Functions and Asymmetries
Ethier, Jacob; Melnitchouk, Wally
2013-10-01
We present a detailed analysis of nuclear effects in inclusive electron scattering from polarized 3He nuclei, including for polarization asymmetries and structure function moments, in both the nucleon resonance and deep-inelastic scattering regions. We compare the results of calculations within the weak binding approximation (WBA) at finite Q2 with several commonly used ansaetze for simplifying the nuclear corrections, and assess their impact on extractions of the free neutron structure. In addition, we make predictions for the Q2 dependence of quasielastic (QE) scattering from polarized 3He, data on which can be used to constrain the nucleon smearing functions in 3He. As a check of the formalism, we compare the WBA calculations in the QE region with the world's data on QE electron-deuteron cross sections.
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.
Structures and Functions of Oligosaccharins
Energy Technology Data Exchange (ETDEWEB)
Albersheim, Peter
1995-12-01
We have made considerable progress during the 2.5 year funding period just ending in our studies of the structures and functions of oligosaccharide signal molecules (oligosaccharins). We have emphasized studies of the enzymes that solubilize, process, and degrade oligosaccharins and of the proteins that inhibit those enzymes. We have been especially interested in elucidating how oligosaccharins and their processing enzymes participate in determining the outcome of challenges to plants by pathogenic microbes. We have studied, to a lesser extent, the roles of oligosaccharins in plant growth and development. Abstracts of papers describing results acquired with support from this grant that have been published, submitted, or in preparation are presented to summarize the progress made during the last two and one half years. The report highlights the most important contributions made in our oiigosaccharin research during this time period, and the corresponding abstract is referenced. Results of work in progress are described primarily in conjunction with our application for continued support.
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...
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
Perturbative QCD study of the polarized structure function g1 at Next-to-Leading-Order
International Nuclear Information System (INIS)
A NLO perturbative study of all available data on polarized structure function g1(x,Q2) is presented. It is first explained how the Q2 evolution was performed using the DGLAP equations, which used with the present data, allow to constrain the behaviour of polarized parton distributions. Implications of such a study are discussed and important quantities are derived such as an estimation of the quark and gluon polarizations in the nucleon. (author)
Nuclear Dependence in Weak Structure Functions and the Determination of Weak Mixing Angle
Athar, M Sajjad; Simo, I Ruiz; Vacas, M J Vicente
2013-01-01
We have studied nuclear medium effects in the weak structure functions $F^A_2(x)$ and $F^A_3(x)$ and in the extraction of weak mixing angle using Paschos Wolfenstein(PW) relation. We have modified the PW relation for nonisoscalar nuclear target. We have incorporated the medium effects like Pauli blocking, Fermi motion, nuclear binding energy, nucleon correlations, pion $\\&$ rho cloud contributions, and shadowing and antishadowing effects.
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)
Study of the Three-Nucleon (e,e') Longitudinal Response Function with a New Approach
Dobretsov, V. Yu.; Efros, V D; Shao, Bin
1993-01-01
A new method for studying the many-body response functions is elaborated and first applied to the $^3$He longitudinal response. An integral transform of the response function is calculated from the bound-state-type equations for several versions of the N-N force. The equations are solved with the help of the hyperspherical expansion. The final-state interaction is completely taken into account. The results are compared with the integral transform of the experimental response...
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.
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.
Diakonov, D I; Diakonov, Dmitri; Petrov, Victor
2000-01-01
In the limit of large number of colors N the nucleon consisting of N quarks is heavy, and one can treat it semiclassically, like the large-Z Thomas--Fermi atom. The role of the semiclassical field binding the quarks in the nucleon is played by the pion or chiral field; its saddle-point distribution inside the nucleon is called the chiral soliton. The old Skyrme model for this soliton is an over-simplification. One can do far better by exploiting a realistic and theoretically-motivated effective chiral lagrangian presented in this paper. As a result one gets not only the static characteristics of the nucleon in a fair accordance with the experiment (such as masses, magnetic moments and formfactors) but also much more detailed dynamic characteristics like numerous parton distributions. We review the foundations of the Chiral Quark-Soliton Model of the nucleon as well as its recent applications to parton distributions, including the recently introduced `skewed' distributions, and to the nucleon wave function on ...
An optimized chiral nucleon-nucleon interaction at next-to-next-to-leading order
Ekström, A; Forssén, C; Hagen, G; Hjorth-Jensen, M; Jansen, G R; Machleidt, R; Nazarewicz, W; Papenbrock, T; Sarich, J; Wild, S M
2013-01-01
We optimize the nucleon-nucleon interaction from chiral effective field theory at next-to-next- to-leading order. The resulting new chiral force NNLOopt yields \\chi^2 \\approx 1 per degree of freedom for laboratory energies below approximately 125 MeV. In the A = 3, 4 nucleon systems, the contributions of three-nucleon forces are smaller than for previous parametrizations of chiral interactions. We use NNLOopt to study properties of key nuclei and neutron matter, and demonstrate that many aspects of nuclear structure can be understood in terms of this nucleon-nucleon interaction, without explicitly invoking three-nucleon forces.
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
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.
International Nuclear Information System (INIS)
Two theoretical approaches to extract the neutron structure functions from combined experimental data on the proton and deuteron are considered. It is shown that the consideration only of the Fermi motion of nucleons in the deuteron in the light cone kinematics gives wrong results at large x (x > 0.7). The meson exchange corrections and binding effects in the deuteron must be taken into account. A new treatment of the experimental neutron structure function obtained from BCDMS-collaboration data is given. (author). 18 refs, 4 figs, 2 tabs
Polarized structure functions in nuclear matter
International Nuclear Information System (INIS)
We present a comprehensive analysis of the structure functions for the polarized nuclei 3He, and focus on the polarized distribution functions and light-cone momentum distributions of protons and neutrons. We demonstrate that the first moment of the 3He structure function can provide an incisive test of the Bjorken sum rule.
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."
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
Meson exchange model for the nucleon-nucleon interaction
International Nuclear Information System (INIS)
Nucleon-nucleon interactions obtained from several models for the field theoretic scattering amplitude are studied. The interaction includes contributions from one-pion and one-omega exchange and from two-pion exchange as calculated in a dispersion theory framework. The resulting interaction is regularized by a cut-off factor obtained by the eikonal approximation to multiple vector meson exchange processes. The Blankenbecler-Sugar equation is solved with the interaction and nucleon-nucleon scattering phase parameters are computed. For the best model good agreement with phenomenological phase parameters is achieved for physically reasonable values of the meson-nucleon coupling constants and the spectral functions needed for the evaluation of the two-pion exchange effects. The deuteron wave function is computed as are the deuteron charge and quadrupole form factors. The interaction is shown to have significantly weaker short-range repulsion than commonly found in local phenomenological potentials and in one-boson exchange models. (Auth.)
Polarized DIS Structure Functions from Neural Networks
International Nuclear Information System (INIS)
We present a parametrization of polarized Deep-Inelastic-Scattering (DIS) structure functions based on Neural Networks. The parametrization provides a bias-free determination of the probability measure in the space of structure functions, which retains information on experimental errors and correlations. As an example we discuss the application of this method to the study of the structure function g1p(x,Q2)
Quark-Hadron Duality in Structure Functions
Fantoni, A.; Bianchi, N.; S. Liuti
2005-01-01
Quark-hadron duality is studied in a systematic way for both the unpolarized and polarized structure functions, by taking into account all the available data in the resonance region.In both cases, a detailed perturbative QCD based analysis of the structure functions integrals in the resonance region is performed: non perturbative contributions are disentangled, and higher twist terms are evaluated. A different behavior between the unpolarized and polarized structure function...
Fermilab Experiment-906/SeaQuest: Exploring Nucleon Structure through the Drell-Yan Process
Ramson, Bryan; SeaQuest Collaboration
2013-10-01
SeaQuest will investigate the large light-flavor asymmetry in the nucleon sea first experimentally observed by the CERN New Muon Collaboration (NMC) and further investigated by Fermilab Experiment-866/NuSea. Through the Drell-Yan process produced in collisions between 120 GeV protons provided by the Fermilab Main Injector and fixed hydrogen and deuterium targets, SeaQuest will measure the ratio of d (xt) and u (xt) at momentum fractions in the interval 0 . 11 Drell-Yan production is enhanced roughly by a factor of seven while background J/ ? production is reduced by the same factor relative to the rates of NuSea's 800 GeV beam. This leads to an enhanced precision by roughly a factor of 50. Additionally, the lower center-of-mass energy and higher precision of the SeaQuest experiment will allow for an enhanced investigation of parton energy loss through cold nuclear matter and significantly improve measurement of the modification of sea quark densities in the nuclear environment. SeaQuest had an initial two month commissioning run in March and April of 2012. Results from the commissioning run and an update on the recently undertaken two year second run will be presented.
The structure and function of cartilage proteoglycans
Directory of Open Access Journals (Sweden)
P J Roughley
2006-11-01
Full Text Available Cartilage contains a variety of proteoglycans that are essential for its normal function. These include aggrecan, decorin, biglycan, fibromodulin and lumican. Each proteoglycan serves several functions that are determined by both its core protein and its glycosaminoglycan chains. This review discusses the structure/function relationships of the cartilage proteoglycans, and the manner in which perturbations in proteoglycan structure or abundance can adversely affect tissue function.
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
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
International Nuclear Information System (INIS)
A model is presented which describes multiquark, nuclear-like systems in a manner consistent with QCD, and with nuclear properties. Within the model, it is found that quasi-nucleon structures describe the minimum energy state of the system. This result is due to a balance between quarks lowering their kinetic energy by spreading out through the system, and lowering their color-magnetic spin-spin interaction energy by forming nucleon-like clusters. A strong core repulsion is evident, as is a realistic dip in the central matter density of the 4He-like, 12-quark system. 4 refs., 5 figs
The EMC Effect and High Momentum Nucleons in Nuclei
Hen, O; Miller, G A; Piasetzky, E; Weinstein, L B
2013-01-01
Recent developments in understanding the influence of the nucleus on deep-inelastic structure functions, the EMC effect, are reviewed. A new data base which expresses ratios of structure functions in terms of the Bjorken variable $x_A=AQ^2/(2M_A q_0)$ is presented. Information about two-nucleon short-range correlations from experiments is also discussed and the remarkable linear relation between short-range correlations and teh EMC effect is reviewed. A convolution model that relates the underlying source of the EMC effect to modification of either the mean-field nucleons or the short-range correlated nucleons is presented. It is shown that both approaches are equally successful in describing the current EMC data.
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
Isospin dependence of nucleon correlations in ground-state nuclei
Energy Technology Data Exchange (ETDEWEB)
Charity, R.J. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Dickhoff, W.H. [Washington University, Department of Physics, St. Louis, Missouri (United States); Sobotka, L.G. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Washington University, Department of Physics, St. Louis, Missouri (United States); Waldecker, S.J. [University of Tennessee, Department of Physics, Chattanooga, Tennessee (United States)
2014-02-15
The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. Such predictions can be investigated by performing experiments with exotic beams. The predicted neutron properties for the double closed-shell {sup 132}Sn nucleus exhibit similar correlations as those in {sup 208}Pb. Future relevance of these studies for understanding the properties of all nucleons, including those with high momentum, and the role of three-body forces in nuclei are briefly discussed. Such an implementation will require a proper treatment of the non-locality of the imaginary part of the potentials and a description of high-momentum nucleons as experimentally constrained by the (e, e' p) reactions performed at Jefferson Lab. (orig.)
Isospin dependence of nucleon correlations in ground-state nuclei
International Nuclear Information System (INIS)
The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. Such predictions can be investigated by performing experiments with exotic beams. The predicted neutron properties for the double closed-shell 132Sn nucleus exhibit similar correlations as those in 208Pb. Future relevance of these studies for understanding the properties of all nucleons, including those with high momentum, and the role of three-body forces in nuclei are briefly discussed. Such an implementation will require a proper treatment of the non-locality of the imaginary part of the potentials and a description of high-momentum nucleons as experimentally constrained by the (e, e' p) reactions performed at Jefferson Lab. (orig.)
International Nuclear Information System (INIS)
An ab initio calculation scheme for finite nuclei based on self-consistent Green's functions in the Gorkov formalism is developed. It aims at describing properties of doubly magic and semimagic nuclei employing state-of-the-art microscopic nuclear interactions and explicitly treating pairing correlations through the breaking of U(1) symmetry associated with particle number conservation. The present paper introduces the formalism necessary to undertake applications at (self-consistent) second order using two-nucleon interactions in a detailed and self-contained fashion. First applications of such a scheme will be reported soon in a forthcoming publication. Future works will extend the present scheme to include three-nucleon interactions and implement more advanced truncation schemes.
Neurotransmitter transporters: structure meets function
Focke, Paul; WANG, XIAOYU; Larsson, H. Peter
2013-01-01
At synapses, sodium-coupled transporters remove released neurotransmitters, thereby recycling them and maintaining a low extracellular concentration of the neurotransmitter. The molecular mechanism underlying sodium-coupled neurotransmitter uptake is not completely understood. Several structures of homologues of human neurotransmitter transporters have been solved with X-ray crystallography. These crystal structures have spurred a plethora of computational and experimental work to elucidate t...
Exploring Three Nucleon Forces in Lattice QCD
Doi, Takumi
2011-01-01
We study the three nucleon force in Nf=2 dynamical clover fermion lattice QCD, utilizing the Nambu-Bethe-Salpeter wave function of the three nucleon system. Since parity-odd two nucleon potentials are not available in lattice QCD at this moment, we develop a new formulation to extract the genuine three nucleon force which requires only the information of parity-even two nucleon potentials. In order to handle the extremely expensive calculation cost, we consider a specific three-dimensional coordinate configuration for the three nucleons. We find that the linear setup is advantageous, where nucleons are aligned linearly with equal spacings. The lattice calculation is performed with 16^3 x 32 configurations at \\beta=1.95, m_\\pi=1.13 GeV generated by CP-PACS Collaboration, and the result of the three nucleon force in triton channel is presented.
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(INFN, Sezione di Bari, via Orabona 4, 70126 , Bari, Italy)
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?...
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? ...
Finite meson size effects in nucleon-nucleon phase shifts
International Nuclear Information System (INIS)
A realistic quark model of the nucleon is used to determine the interaction between two nucleons. A scalar potential is utilized to confine the quarks and to determine the quark wave function by solving a Dirac equation. Chiral symmetry suggests that confined quarks are surrounded by a pion cloud. A local pion quark interaction is used to determine the energy of such a pion cloud with parameters chosen to reproduce the pion-nucleon coupling found in one-boson exchange potentials. For a finite pion size, the cloud energy is finite. The pion cloud energy is included in variational non-relativistic quark model determination of the nucleon mass. A stable nucleon of the right size and mass comes out of this calculation. The form factors for the one-boson exchange potential are calculated taking finite meson size into account. The OBEP is combined with a non-relativistic quark model of the nucleon to provide input into a resonating group theory to calculate the two nucleon phase shifts. The two nucleon 1S0 phase shifts calculated agree well with experiment. The net effect of finite meson size in this model is a slightly smaller phase shift. (author)
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
Neurotransmitter transporters: structure meets function.
Focke, Paul J; Wang, Xiaoyu; Larsson, H Peter
2013-05-01
At synapses, sodium-coupled transporters remove released neurotransmitters, thereby recycling them and maintaining a low extracellular concentration of the neurotransmitter. The molecular mechanism underlying sodium-coupled neurotransmitter uptake is not completely understood. Several structures of homologs of human neurotransmitter transporters have been solved with X-ray crystallography. These crystal structures have spurred a plethora of computational and experimental work to elucidate the molecular mechanism underlying sodium-coupled transport. Here, we compare the structures of GltPh, a glutamate transporter homolog, and LeuT, a homolog of neurotransmitter transporters for the biogenic amines and inhibitory molecules GABA and glycine. We relate these structures to data obtained from experiments and computational simulations, to draw conclusions about the mechanism of uptake by sodium-coupled neurotransmitter transporters. Here, we propose how sodium and substrate binding is coupled and how binding of sodium and substrate opens and closes the gates in these transporters, thereby leading to an efficient coupled transport. PMID:23664361
Constraining nucleon strangeness
Hobbs, T. J.; Alberg, Mary; Miller, Gerald A.
2015-03-01
Determining the nonperturbative s s ¯ content of the nucleon has attracted considerable interest and has been the subject of numerous experimental searches. These measurements used a variety of reactions, and place important limits on the vector form factors observed in parity-violating (PV) elastic scattering and the parton distributions determined by deep inelastic scattering (DIS). In spite of this progress, attempts to relate information obtained from elastic and DIS experiments have been sparse. To ameliorate this situation, we develop an interpolating model using light-front wave functions capable of computing both DIS and elastic observables. This framework is used to show that existing knowledge of DIS places significant restrictions on our wave functions. The result is that the predicted effects of nucleon strangeness on elastic observables are much smaller than those tolerated by direct fits to PV elastic scattering data alone. Using our model, we find -0.024 ??s?0.035 and -0.137 ??sD?0.081 for the strange contributions to the nucleon magnetic moment and charge radius. The model we develop also independently predicts the nucleon's strange spin content ? s and scalar density , and for these we find agreement with previous determinations.
Ryanodine receptors: structure and function.
Van Petegem, Filip
2012-09-14
Ryanodine receptors (RyRs) are huge ion channels that are responsible for the release of Ca(2+) from the sarco/endoplasmic reticulum. RyRs form homotetramers with a mushroom-like shape, consisting of a large cytoplasmic head and transmembrane stalk. Ca(2+) is a major physiological ligand that triggers opening of RyRs, but a plethora of modulatory proteins and small molecules in the cytoplasm and sarco/endoplasmic reticulum lumen have been recognized. Over 300 mutations in RyRs are associated with severe skeletal muscle disorders or triggered cardiac arrhythmias. With the advent of high-resolution structures of individual domains, many of these can be mapped onto the three-dimensional structure. PMID:22822064
International Nuclear Information System (INIS)
The Bates Large Acceptance Spectrometer Toroid (BLAST) is a detector designed to study the spin-dependent electromagnetic response of few-body nuclei at momentum transfers up to 1 (GeV/c)2 at the MIT/Bates Linear Accelerator Center's South Hall Ring (SHR). The BLAST detector consists of an eight-sector copper coil array producing a toroidal magnetic field, instrumented with two opposing wedge-shaped sectors of wire chambers, scintillation detectors, Cerenkov counters, neutron detectors, a lead-glass forward calorimeter, and recoil detectors. The ability of BLAST to carry out multi-particle detection over a large solid angle from polarized internal targets will provide an unprecedented and unique opportunity to study simultaneously the spin structure of the few-body nuclear ground states, the reaction mechanisms, and the nucleon form factors. Presently, BLAST is under construction and it is on schedule to be done in summer 2001. A status of the project is presented as well as highlights of the scientific program
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.
Guegan, Baptiste
2012-01-01
The Generalized Parton Distributions (GPDs) provide a new description of the nucleon structure in terms of its elementary constituents, the quarks and the gluons. The GPDs give access to a unified picture of the nucleon, correlating the information obtained from the measurements of the Form Factors and the Parton Distribution Functions. They describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon.Deeply Virtual Compton Scat...
The dynamic of diffractive structure functions
Monfared, S Taheri; Tehrani, S Atashbar
2011-01-01
We extract diffractive parton distribution functions (DPDFs) and diffractive structure functions from the most recent H1 and ZEUS diffractive DIS data obtained by various methods. We consider Pomeron as an object with parton distribution function, evolving according to the next-to-leading order (NLO) DGLAP equations within the framework of the `Fixed Flavour Number Scheme' (FFNS). Having performed a global fit analysis, we achieve a very good description of all available measurements by introducing a new set of quark distribution form for the Pomeron. We predict longitudinal and charm proton diffractive structure function as well. Our results are compared with other analysis from the literature.
Lepton Scattering Cross Section and Nuclear Structure Function of 4He and 12C Nuclei
Directory of Open Access Journals (Sweden)
Mir Hamid Musavi
2013-10-01
Full Text Available This paper is an effort to extract the structure function, the EMC ratio, and the lepton scattering cross section in the convolution nuclear theory framework for 4He and 12C nuclei. We suppose that, in conventional approach, based on harmonic oscillator model, one could consider for a nucleus shell different hw parameters which are associated with the square root of the mean radius of the nucleus shells. We use GRV free nucleon structure function, which has good agreement with the proton and neutron structure function, extracted from experimental results. In addition, the lepton scattering cross sections of 4He and 12C nuclei are calculated in energy higher than 1 GeV. The extracted results show good agreement with experimental data.
Unquenched simulations of four-nucleon interactions
Energy Technology Data Exchange (ETDEWEB)
Montvay, I.
2012-10-15
Exploratory simulations of four-nucleon interactions are performed taking into account the dynamical effects of internal nucleon loops. The four-nucleon interactions in the isoscalar and isovector channels are described by Yukawa interactions with auxiliary scalar fields. The nucleon mass and the average field lengths of the scalar fields are determined as a function of nucleon hopping parameter and Yukawa coupling strengths. There are no problems with ''exceptional configurations'' at strong couplings which make quenched simulations unreliable.
Four RNA families with functional transient structures.
Zhu, Jing Yun A; Meyer, Irmtraud M
2015-01-01
Protein-coding and non-coding RNA transcripts perform a wide variety of cellular functions in diverse organisms. Several of their functional roles are expressed and modulated via RNA structure. A given transcript, however, can have more than a single functional RNA structure throughout its life, a fact which has been previously overlooked. Transient RNA structures, for example, are only present during specific time intervals and cellular conditions. We here introduce four RNA families with transient RNA structures that play distinct and diverse functional roles. Moreover, we show that these transient RNA structures are structurally well-defined and evolutionarily conserved. Since Rfam annotates one structure for each family, there is either no annotation for these transient structures or no such family. Thus, our alignments either significantly update and extend the existing Rfam families or introduce a new RNA family to Rfam. For each of the four RNA families, we compile a multiple-sequence alignment based on experimentally verified transient and dominant (dominant in terms of either the thermodynamic stability and/or attention received so far) RNA secondary structures using a combination of automated search via covariance model and manual curation. The first alignment is the Trp operon leader which regulates the operon transcription in response to tryptophan abundance through alternative structures. The second alignment is the HDV ribozyme which we extend to the 5' flanking sequence. This flanking sequence is involved in the regulation of the transcript's self-cleavage activity. The third alignment is the 5' UTR of the maturation protein from Levivirus which contains a transient structure that temporarily postpones the formation of the final inhibitory structure to allow translation of maturation protein. The fourth and last alignment is the SAM riboswitch which regulates the downstream gene expression by assuming alternative structures upon binding of SAM. All transient and dominant structures are mapped to our new alignments introduced here. PMID:25751035
Structure Function Studies for Turbulent Interstellar Medium
Sun, X H; Han, J.L.
2004-01-01
We study structure functions of rotation measures in the Canadian Galactic Plane Survey (CGPS) region and the North Galactic Pole (NGP) to extract the interstellar medium (ISM) fluctuation information. The CGPS data are divided into three longitude intervals: $82^\\circ
New Parametrizations for the Photon Structure Function
International Nuclear Information System (INIS)
In the last year four new parametrizations of the Hadronic Photon Structure Function at Next to Leading Order have appeared. In this talk, I briefly review the main features of the three of them: the FFNSCJK, CJK and AFG. (author)
Watanabe, Akira; Suzuki, Katsuhiko
2012-01-01
We study the nucleon and pion structure functions at small Bjorken-$x$ region in the framework of holographic QCD with a special emphasis on the roles of AdS space wave functions. Using the BPST kernel for the Pomeron exchange and calculating its coupling to target hadrons in the AdS space, we obtain $F_2$ structure functions at the small-$x$. Results for the proton $F^p_2$ as well as the pion $F^\\pi_2$ are consistent with experimental data of the deep inelastic scattering a...
Neutrino-production of a charmed meson and the transverse spin structure of the nucleon
Pire, B
2015-01-01
We calculate the amplitude for exclusive neutrino production of a charmed meson on an unpolarized target, in the colinear 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 mc/Q. We show how to access these GPDs through the azimuthal dependence of the nu N -> mu D N differential cross section.
Recent Structure Function Results from CCFR
Fleming, B T; Alton, A; Arroyo, C G; Avvakumov, S; De Barbaro, L; De Barbaro, P; Bazarko, A O; Bernstein, R H; Bodek, Arie; Bolton, T; Brau, J E; Buchholz, D; Budd, H S; Bugel, L; Conrad, J; Drucker, R B; Formaggio, J A; Frey, R; Goldman, J; Goncharov, M; Harris, D A; Johnson, R A; Kim, J H; King, B J; Kinnel, T; Koutsoliotas, S; Lamm, M J; Marsh, W; Mason, D; McFarland, K S; McNulty, C; Mishra, S R; Naples, D; Nienaber, P; Romosan, A; Sakumoto, W K; Schellman, H; Sciulli, F J; Seligman, W G; Shaevitz, M H; Smith, W H; Spentzouris, P; Stern, E G; Vakili, M; Vaitaitis, A G; Yang, U K; Yu, J; Zeller, G P; Zimmerman, E D
2000-01-01
A new structure function analysis of CCFR deep inelastic nu-N and nubar-N scattering data is presented for previously unexplored kinematic regions down to Bjorken x=0.0045 and Q^2=0.3 GeV^2. Comparisons to charged lepton scattering data from NMC and E665 experiments are made and the behavior of the structure function F2_nu is studied in the limit Q^2 -> 0
A Cook Book of Structure Functions
Kellerer, Aglae
2015-01-01
The structure function is a useful quantity to characterize wavefront distortions. We derive expressions for the structure functions of the averaged wavefront phase and slopes. The expressions are valid within the inertial range of atmospheric turbulence, and are meant to serve as engineering formulae when reconstructing profiles of the atmospheric turbulence, specifically in the context of atmospheric profiling instruments (e.g. SLODAR and S-DIMM+) and multi-conjugate adapt...
A Cook Book of Structure Functions
Kellerer, Aglae
2015-01-01
The structure function is a useful quantity to characterize wavefront distortions. We derive expressions for the structure functions of the averaged wavefront phase and slopes. The expressions are valid within the inertial range of atmospheric turbulence, and are meant to serve as engineering formulae when reconstructing profiles of the atmospheric turbulence, specifically in the context of atmospheric profiling instruments (e.g. SLODAR and S-DIMM+) and multi-conjugate adaptive optical systems.
Chiral Symmetry and the Nucleon-Nucleon Interaction
Machleidt, R.
2011-01-01
The main progress in the field of nucleon-nucleon (NN) potentials, which we have seen in recent years, is the construction of some very quantitative (high-quality/high-precision) NN potentials. These potentials will serve as excellent input for microscopic nuclear structure calculations and will allow for a systematic investigation of off-shell effects. After this enormous quantitative work, it is now time to re-think the NN problem in fundamental terms. We need a derivation...
Density functional theory and electronic structure
International Nuclear Information System (INIS)
The paper presents an overview of the density functional theory and provides a brief appraisal of the latest developments of the theory. Particular emphasis is placed on the understanding of the electronic structure of materials via the density functional theory. 37 refs, 1 tab
Structure function of pion and its compositeness
International Nuclear Information System (INIS)
Using recent data on pion structure function and a rigorous inequality obtained recently using unitarity analyticity and Bjorken scaling a numerical upper bound on the wave-function-renormalisation constant of pion is computed. By the (somewhat drastic) act of neglecting the sea, it is shown that the bare part of the pion can be no more than 38%. (auth.)
Feminine Faces of Leadership: Beyond Structural- Functionalism?
Fennell, Hope-Arlene
1999-01-01
Reviews four philosophical leadership perspectives: structural-functionalism, constructivism, critical theory, and feminism. Explores the leadership phenomenon through the eyes of six women principals. Although the behaviors of all six fall within a structural-functionalist perspective, each is attempting to construct inclusive, positive, and…
Spin structure function of the virtual photon
Sasaki, Ken; Uematsu, Tsuneo
1999-01-01
We investigate the spin structure of the virtual photon beyond the leading order in QCD. The first moment of the virtual photon spin structure function $g_1^\\gamma(x,Q^2,P^2)$ with QCD effects turns out to be non-vanishing in contrast to the real photon case. Numerical analysis for virtual as well as real photon case is presented.
Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon
Kanazawa, K.; Lorce?, C.; Metz, A.; Pasquini, B.; Schlegel, M.
2014-01-01
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 $F_{1,4}$ and $G_{1,1}$ 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 $F_{1,4}$ and $G_{1,1}$ has been doubted. We explain why this claim does not hold. W...
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.
Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon
Kanazawa, K; Metz, A; Pasquini, B; Schlegel, M
2014-01-01
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 $F_{1,4}$ and $G_{1,1}$ 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 $F_{1,4}$ and $G_{1,1}$ 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 $F_{1,4}$ and $G_{1,1}$ at large transverse momentum in perturbative Quantum Chromodynamics and show that they are nonzero.
Neutrino-pair bremsstrahlung from nucleon-? versus nucleon-nucleon scattering
Sharma, Rishi; Bacca, Sonia; Schwenk, A.
2015-04-01
We study the impact of the nucleon-? P -wave resonances on neutrino-pair bremsstrahlung. Because of the noncentral spin-orbit interaction, these resonances lead to an enhanced contribution to the nucleon spin structure factor for temperatures T ?4 MeV. If the ? -particle fraction is significant and the temperature is in this range, this contribution is competitive with neutron-neutron bremsstrahlung. This may be relevant for neutrino production in core-collapse supernovae or other dense astrophysical environments. Similar enhancements are expected for resonant noncentral nucleon-nucleus interactions.
Neutrino-pair bremsstrahlung from nucleon-$\\alpha$ versus nucleon-nucleon scattering
Sharma, Rishi; Schwenk, Achim
2014-01-01
We study the impact of the nucleon-$\\alpha$ P-wave resonances on neutrino-pair bremsstrahlung. Because of the non-central spin-orbit interaction, these resonances lead to an enhanced contribution to the nucleon spin structure factor for temperatures $T \\lesssim 4$ MeV. If the $\\alpha$-particle fraction is significant and the temperature is in this range, this contribution is competitive with neutron-neutron bremsstrahlung. This may be relevant for neutrino production in core-collapse supernovae or other dense astrophysical environments. Similar enhancements are expected for resonant non-central nucleon-nucleus interactions.
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.
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.
New model for nucleon generalized parton distributions
Energy Technology Data Exchange (ETDEWEB)
Radyushkin, Anatoly V. [JLAB, Newport News, VA (United States)
2014-01-01
We describe a new type of models for nucleon generalized parton distributions (GPDs) H and E. They are heavily based on the fact nucleon GPDs require to use two forms of double distribution (DD) representations. The outcome of the new treatment is that the usual DD+D-term construction should be amended by an extra term, {xi} E{sub +}{sup 1} (x,{xi}) which has the DD structure {alpha}/{beta} e({beta},{alpha}, with e({beta},{alpha}) being the DD that generates GPD E(x,{xi}). We found that this function, unlike the D-term, has support in the whole -1 <= x <= 1 region. Furthermore, it does not vanish at the border points |x|={xi}.
Moments of the Proton F2 Structure Function at Low Q2
Armstrong, C. S.; Ent, R.; Keppel, C. E.; Liuti, S.; Niculescu, G.; Niculescu, I.
2001-01-01
The Q^2 dependence of inclusive electron-proton scattering F_2 structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c)^2, is investigated. Moments of F_2 are constructed, down to momentum transfers of Q^2 ~ 0.1 (GeV/c)^2. The second moment is only slowly varying with Q^2 down to Q^2 ~ 1 (GeV/c)^2, which is a reflection of duality. Below Q^2 of 1 (GeV/c)^2, the Q^2 dependence of the moments is predomina...
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...
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)
Spin-orbit coupling in nuclei and realistic nucleon-nucleon potentials
Kaiser, N.
2004-09-01
We analyze the spin-orbit coupling term in the nuclear energy density functional in terms of a zero-range NN-contact interaction and finite-range contributions from two-pion exchange. We show that the strength of the spin-orbit contact interaction as extracted from high-precision nucleon-nucleon potentials is in perfect agreement with that of phenomenological Skyrme forces employed in non-relativistic nuclear structure calculations. Additional long-range contributions from chiral two-pion exchange turn out to be relatively small. These explicitly density-dependent contributions reduce the ratio of the isovector to the isoscalar spin-orbit strength significantly below the Skyrme value 1/3 . We perform a similar analysis for the strength function of the (??)2 -term and find values not far from those of phenomenological Skyrme parametrizations.
Spin-orbit coupling in nuclei and realistic nucleon-nucleon potentials
Kaiser, N
2004-01-01
We analyze the spin-orbit coupling term in the nuclear energy density functional in terms of a zero-range NN-contact interaction and finite-range contributions from two-pion exchange. We show that the strength of the spin-orbit contact interaction as extracted from high-precision nucleon-nucleon potentials is in perfect agreement with that of phenomenological Skyrme forces employed in non-relativistic nuclear structure calculations. Additional long-range contributions from chiral two-pion exchange turn out to be relatively small. These explicitly density-dependent contributions reduce the ratio of the isovector to the isoscalar spin-orbit strength significantly below the Skyrme value 1/3. We perform a similar analysis for the strength function of the $(\\vec \
Boson structure functions from inelastic electron scattering
International Nuclear Information System (INIS)
The even /sup 104-110/Pd isotopes and /sup 196/Pt have been investigated at NIKHEF-K by high-resolution inelastic electron scattering. A new IBA-2 calculation has been performed for the Pd isotopes, in which the ratio of the proton and neutron coupling constants is taken from pion scattering. One set of boson structure functions sufficed for the description of the first and second E2-excitations in all Pd isotopes. The data showed no sensitivity for different structure functions for proton and neutron bosons. A preliminary analysis of a number of negative parity states (3/sup -/,5/sup -/ and 7/sup -/), observed in /sup 196/Pt, was performed through the introduction of an f-boson. The first E4-excitation in the palladium isotopes can be reasonably described with a ?-structure function, but all other E4-excitations require the introduction of g-boson admixtures
THE STRUCTURED MODEL FOR FUNCTION ALLOCATION ANALYSIS
Directory of Open Access Journals (Sweden)
SUNG-GYUN OH
2015-02-01
Full Text Available For successful function allocation analysis, there is a need for collaboration of all stakeholders affected by the life cycle of the system. This Article presents the structured design model that can support the functional analysis activities of multidisciplinary team and their communication. We created the human task and system functional model by using the Design Structure Matrix. Also, by using this model, we built the automation model supporting the human perception, decision and Action. For the efficiency of analysis activities, we ensured convertibility with the IDEF-0, the conventional system design modeling language. To validate the effectiveness of the analysis activities using this model, we applied the analysis activities to specific task for safety personnel among the subway station fire response scenarios. Based on the results, we defined the automation function of safety personnel’s task.
Structure Functions of Unstable Lithium Isotopes
Saito, K.; Ueda, M.; Tsushima, K.; Thomas, A.W.
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...
Determination of the neutron spin structure function
International Nuclear Information System (INIS)
The spin structure function of the neutron, g1n, has been determined over the range 0.032 of 2 (GeV/c)2 by measuring the asymmetry in deep inelastic scattering of polarized electrons from a polarized 3He target at energies between 19 and 26 GeV. The integral of the neutron spin structure function is found to be ?01g1n(x)dx=-0.022±0.011. Earlier reported proton results together with the Bjorken sum rule predict ?01g1n(x)dx=-0.065±0.019. (author) 22 refs.; 3 figs
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...
International Nuclear Information System (INIS)
This report details progress toward completion of a long-term pion-nucleon partial wave analysis, summarizing results and conclusions to date. The report also discussed progress in using partial wave and resonance parameter results to test dynamical models of the baryon and in better understanding interquark forces within baryons
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; ...
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.
Strangeness and meson-nucleon sigma terms
Dahiya, Harleen
2011-01-01
The chiral constituent quark model ($\\chi$CQM) has been extended to calculate the flavor structure of the nucleon through the meson-nucleon sigma terms which have large contributions from the quark sea and are greatly affected by chiral symmetry breaking and SU(3) symmetry breaking. The hidden strangeness component in the nucleon has also been investigated and its significant contribution is found to be consistent with the recent available experimental observations.
Structure Function Studies for Turbulent Interstellar Medium
Han, X H S J L
2004-01-01
We study structure functions of rotation measures in the Canadian Galactic Plane Survey (CGPS) region and the North Galactic Pole (NGP) to extract the interstellar medium (ISM) fluctuation information. The CGPS data are divided into three longitude intervals: $82^\\circ1^\\circ$. The power law indices get smaller from CGPS1 to CGPS3 and the amplitudes decrease. The variations of the large-scale field and the electron density have only negligible effects on the structure function and thus cannot account for the changes, indicating that the turbulent properties of the Galactic ISM are intrinsically longitude-dependent. The Kolmogorov-like fluctuation spectrum of the electron density or the magnetic field should produce a power law structure function with an index of 5/3 or 2/3, neither of which is consistent with our results of small indices in the three sub-CGPS regions. For the NGP region, the structure function is flat, showing that the rotation measures are mostly intrinsic to the extragalactic sources, and t...
International Nuclear Information System (INIS)
Using BEBC equipped with a hydrogen-filled neon-surrounded track sensitive target, the charged current cross sections and structure functions of hydrogen and neon targets traversed by the same neutrinos and antineutrinos are compared directly. The measured total cross section ratios between hydrogen and neon allow precise total cross section values for hydrogen to be inferred. Using this normalisation, the ? and ?-bar hydrogen data are combined and the quark distributions in free nucleons, parametrised as functions of xi, are extracted. This free-nucleon parametrisation is then compared directly with the neon data in order to measure nuclear effects such as those recently reported by the EMC collaboration. Only small effects are seen, in excellent agreement with recent SLAC data in a more similar A and q2 range. (author)
From RHIC to EIC: Nuclear Structure Functions
Jalilian-Marian, Jamal
2009-01-01
We study the nuclear structure function $F_2^A$ and its logarithmic derivative in the high energy limit (small $x$ region) using the Color Glass Condensate formalism. In this limit the structure function $F_2$ depends on the quark anti-quark dipole-target scattering cross section $N_F (x_{bj}, r_t, b_t)$. The same dipole cross section appears in single hadron and hadron-photon production cross sections in the forward rapidity region in deuteron (proton)-nucleus collisions at high energy, i.e. at RHIC and LHC. We use a parameterization of the dipole cross section, which has successfully been used to describe the deuteron-gold data at RHIC, to compute the nuclear structure function $F_2^A$ and its log $Q^2$ derivative (which is related to gluon distribution function in the double log limit). We provide a quantitative estimate of the nuclear shadowing of $F_2^A$ and the gluon distribution function in the kinematic region relevant to a future Electron-Ion Collider.
Generalized functions, convergence structures, and their applications
Pap, Endre; Pilipovi?, Stevan; Vladimirov, Vasilij
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...
Measurement of the Fifth Structure Function in Deuterium
Dolfini, Stephen Michael
We report the first measurement of the 5 ^{th} structure function, f _sp{01}{'}, in deuterium. In conjunction with deuterium, f _sp{01}{'} was measured in carbon. These measurements constitute the first ever observations of these structure functions and the inauguration of the newly developed Out-Of-Plane Spectrometer (OOPS). The observation of f_sp {01}{'} requires longitudinally polarized electron beams and out-of-plane detection. This structure function is directly related to the imaginary part of the interference between the transverse and longitudinal nuclear electromagnetic currents. Therefore, f _sp{01}{'} vanishes identically if only a single amplitude contributes to the observed reaction channel. In our experiment the two dominant amplitudes that interfere, giving rise to f_sp{01}{'}, are the ones due to the direct knock-out and rescattering processes. This ^2H({vec e}, e^' p)n experiment was conducted at the MIT/Bates Linear Accelerator Center in July, 1991. An important part of this work was to develop the methodology for out-of-plane physics as well as design, construct and test the spectrometer system in performing out-of-plane measurements at Bates. The system is capable of accessing a wide range of out-of-plane angles and performing high precision coincidence measurements on the nucleon and few body systems. We used a 560 MeV polarized electron beam. The OOPS was sequentially placed at three out-of-plane angles. The electron spectrometer, ELSSY, was placed at an angle of 40^circ and was tuned for quasi-elastic kinematics with the square of the four-momentum transfer, rm Q^2, equal to -3.3 rm fm^{ -2}. In this region, the response of the deuteron has been explored before and is well understood: contributions to the cross section from processes such as meson exchange currents and isobar configurations are minimal and f _sp{01}{'} is particularly sensitive to final state interactions. We demonstrated that the OOPS is optimized for out-of-plane spectrometry and have thus ushered in a new tool for electron scattering. We measured f_sp {01}{'} and the related asymmetry in the coincidence cross section, albeit with large statistical errors, and have shown them to be in agreement with the theoretical predictions of Arenhovel.
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.
Experimental review of the photon structure function
International Nuclear Information System (INIS)
The photon structure function F/sup ?//sub 2/ is considered an excellent tool to test QCD. Unlike baryons and mesons, the photon couples pointlike to quarks. This pointlike coupling gives rise to a contribution to the photon structure function, which is unique. It is absolutely calculable in perturbative QCD, and (unlike baryons and mesons) it rises with chi and Q/sup 2/. Furthermore, as a result of the quark propagator, it is sensitive to an energy scale, given by the quark mass in the QPM (F/sup ?//sub 2/ -- iotan (W/sup 2//m/sup 2/)/sub q/) and by ? in QCD (F/sup ?//sub 2/ -- iotan (Q/sup 2//?/sup 2/)). The sensitivity to this scale is demonstrated by the TPC/2? Collaboration, for the muonic photon structure function, which allows a 5% measurement of the muon mass. A measurement at only one fixed value of Q/sup 2/ allows a determination of ?/sub M-barS-bar/ to a similar precision. The photon structure function contains an additional piece coming from the hadronic matrix element of the photon which is not calculable perturbatively. As for any other hadron, only the Q/sup 2/ dependence is predicted. One therefore has to make assumptions about this hadronic piece or try to measure it experimentally. Usually the hadronic component of the photon to the pion structure function is related, resulting in F/sup HAD//sub 2/= 0.2?(1-x). An alternative approach is to study the Q/sup 2/ evolution only, which is safely predicted by QCD, but shows only little sensitivity tut shows only little sensitivity to ?
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.
Nucleon-nucleon theory and phenomenology
International Nuclear Information System (INIS)
This project involves five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the ?N and ?? physical regions of the N anti N ? ?? amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 0-1200 MeV range that can be used by all nucleon-nucleon reseachers
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).
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)
Charge-dependent three-nucleon potential
International Nuclear Information System (INIS)
The charge-dependent three-nucleon potential due to simultaneous photon and pion exchange was derived. The intermediate state of the three-nucleon system was considered to consist of a ?(1236) resonance. The contribution of this charge-dependent three-nucleon potential to the charge asymmetric energy of 3He-3H is then evaluated using a reasonable trial wave function for a three- nucleon bound system. This contribution turns out to be small but makes the charge asymmetric energy of 3He-3H slightly larger. (orig.)
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...
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...
Structurally-informed Bayesian functional connectivity analysis.
Hinne, Max; Ambrogioni, Luca; Janssen, Ronald J; Heskes, Tom; van Gerven, Marcel A J
2014-02-01
Functional connectivity refers to covarying activity between spatially segregated brain regions and can be studied by measuring correlation between functional magnetic resonance imaging (fMRI) time series. These correlations can be caused either by direct communication via active axonal pathways or indirectly via the interaction with other regions. It is not possible to discriminate between these two kinds of functional interaction simply by considering the covariance matrix. However, the non-diagonal elements of its inverse, the precision matrix, can be naturally related to direct communication between brain areas and interpreted in terms of partial correlations. In this paper, we propose a Bayesian model for functional connectivity analysis which allows estimation of a posterior density over precision matrices, and, consequently, allows one to quantify the uncertainty about estimated partial correlations. In order to make model estimation feasible it is assumed that the sparseness structure of the precision matrices is given by an estimate of structural connectivity obtained using diffusion imaging data. The model was tested on simulated data as well as resting-state fMRI data and compared with a graphical lasso analysis. The presented approach provides a theoretically solid foundation for quantifying functional connectivity in the presence of uncertainty. PMID:24121202
A narrow structure in the excitation function of eta-photoproduction off the neutron
Werthmueller, D; Keshelashvili, I; Aguar-Bartolome, P; Ahrens, J; Annand, J R M; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Demissie, B; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Glazier, D I; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Huber, G M; Jaegle, I; Jahn, O; Jude, T C; Kaeser, A; Kashevarov, V L; Kondratiev, R; Korolija, M; Kruglov, S P; Krusche, B; Kulbardis, A; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McNicoll, E F; Metag, V; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S N; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D; Starostin, A; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P
2013-01-01
The photoproduction of $\\eta$-mesons off nucleons bound in $^2$H and $^3$He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the $\\eta\\rightarrow 2\\gamma$ and $\\eta\\rightarrow 3\\pi^0$ decays and the recoil nucleons were detected with an almost $4\\pi$ electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of $\\gamma n\\rightarrow n\\eta$. The results from the two measurements are consistent taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are $W$ = (1670$\\pm$5) MeV and $\\Gamma$ =(30$\\pm$15) MeV. For the first time precise results for the angular dependence of this structure have been ext...
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)
Perinatal Choline Influences Brain Structure and Function
Zeisel, Steven H.; Niculescu, Mihai D.
2008-01-01
Choline is derived not only from the diet, but also from de novo synthesis. It is important for methyl-group metabolism, the formation of membranes, kidney function, and neurotransmission. When deprived of dietary choline, most adult men and postmenopausal women develop signs of organ dysfunction (fatty liver or muscle damage) and have a decreased capacity to convert homocysteine to methionine. Choline is critical during fetal development, when it influences stem cell proliferation and apoptosis, thereby altering brain structure and function (memory is permanently enhanced in rodents exposed to choline during the latter part of gestation). PMID:16673755
Structure of BRS-invariant local functionals
International Nuclear Information System (INIS)
For a large class of gauge theories a nilpotent BRS-operator s is constructed and its cohomology in the space of local functionals of the off-shell fields is shown to be isomorphic to the cohomology of s=s+d on functions f(C,T) of tensor fields T and of variables C which are constructed of the ghosts and the connection forms. The result allows general statements about the structure of invariant classical actions and anomaly cadidates whose BRS-variation vanishes off-shell. The assumptions under which the result holds are thoroughly discussed. (orig.)
Universality of nucleon–nucleon short-range correlations and nucleon momentum distributions
International Nuclear Information System (INIS)
By analyzing recent microscopic many-body calculations of few-nucleon systems and complex nuclei performed by different groups in terms of realistic nucleon–nucleon (NN) interactions, it is shown that NN short-range correlations (SRCs) have a universal character, in that the correlation hole that they produce in nuclei appears to be almost A-independent and similar to the correlation hole in the deuteron. The correlation hole creates high-momentum components, missing in a mean-field (MF) description and exhibiting several scaling properties and a peculiar spin–isospin structure. In particular, the momentum distribution of a pair of nucleons in spin–isospin state (ST) = (10), depending upon the pair relative (krel) and center-of-mass (c.m.) (Kc.m.) momenta, as well as upon the angle ? between them, exhibits a remarkable property: in the region krel?2 fm-1 and Kc.m.?1 fm-1, the relative and c.m. motions are decoupled and the two-nucleon momentum distribution factorizes into the deuteron momentum distribution and an A-dependent momentum distribution describing the c.m. motion of the pair in the medium. The impact of these and other properties of one- and two-nucleon momentum distributions on various nuclear phenomena, on ab initio calculations in terms of low-momentum interactions, as well as on ongoing experimental investigations of SRCs, are briefly commented. (author)
Oblique photon expansion of QED structure functions
International Nuclear Information System (INIS)
In the oblique photon expansion, the collinear part of photon emission is summed up to all orders in perturbation theory. The number of oblique or non-collinear photons is the expansion order. Unlike in perturbation theory, every term of the expansion is both infrared finite and gauge invariant. The zero oblique photon contribution to the electromagnetic structure tensor in QED is computed in detail. The behaviors of the structure functions F1 and F2 are discussed in the soft and ultra-soft limits
Red cell antigens: Structure and function
Directory of Open Access Journals (Sweden)
Pourazar Abbasali
2007-01-01
Full Text Available Landsteiner and his colleagues demonstrated that human beings could be classified into four groups depending on the presence of one (A or another (B or both (AB or none (O of the antigens on their red cells. The number of the blood group antigens up to 1984 was 410. In the next 20 years, there were 16 systems with 144 antigens and quite a collection of antigens waiting to be assigned to systems, pending the discovery of new information about their relationship to the established systems. The importance of most blood group antigens had been recognized by immunological complications of blood transfusion or pregnancies; their molecular structure and function however remained undefined for many decades. Recent advances in molecular genetics and cellular biochemistry resulted in an abundance of new information in this field of research. In this review, we try to give some examples of advances made in the field of ?structure and function of the red cell surface molecules.?
Geometrical scaling in charm structure function ratios
Boroun, G R
2014-01-01
By using a Laplace-transform technique, we solve the next-to-leading-order master equation for charm production and derive a compact formula for the ratio $R^{c}=\\frac{F^{^{c\\overline{c}}}_L}{F^{^{c\\overline{c}}}_2}$, which is useful for extracting the charm structure function from the reduced charm cross section, in particular, at DESY HERA, at small x. Our results show that this ratio is independent of xat small x. In this method of determining the ratios, we apply geometrical scaling in charm production in deep inelastic scattering (DIS). Our analysis shows that the renormalization scales have a sizable impact on the ratio Rcat high $Q^{2}$. Our results for the ratio of the charm structure functions are in a goodagreement with some phenomenological models.
Spin-orbit correlations in the nucleon
Lorcé, Cédric
2014-07-01
We investigate the correlations between the quark spin and orbital angular momentum inside the nucleon. Similarly to the Ji relation, we show that these correlations can be expressed in terms of specific moments of measurable parton distributions. This provides a whole new piece of information about the partonic structure of the nucleon.
The Longitudinal Proton Structure Function at HERA
Schwartz, Jason
2010-01-01
The longitudinal proton structure function (FL) has been measured at the HERA collider in positron-proton deep inelastic scattering collisions with the H1 and ZEUS detectors. This measurement is achieved by using multiple center-of-mass energies (sqrt(s)) via a reduction of the proton beam energy. The energies used for this measurement are sqrt(s) = 318, 251, 225 GeV. The kinematic region studied is 2.5
Antimicrobial peptides: structure, function and resistance
Vargues, Thomas
2009-01-01
Higher eukaryotes produce a vast range of antimicrobial peptides (AMPs) that play important roles in their defence against microbial infection. Beta defensins are small (3-5 kDa), cationic peptides that display broad, potent antimicrobial activity against a range of microbes and also act as chemoattractants of important immunomodulatory cells. To generate highly pure peptides for structural and functional studies, we developed a method to prepare recombinant human beta defensin...
Structural and regulatory functions of keratins
International Nuclear Information System (INIS)
The diversity of epithelial functions is reflected by the expression of distinct keratin pairs that are responsible to protect epithelial cells against mechanical stress and to act as signaling platforms. The keratin cytoskeleton integrates these functions by forming a supracellular scaffold that connects at desmosomal cell-cell adhesions. Multiple human diseases and murine knockouts in which the integrity of this system is destroyed testify to its importance as a mechanical stabilizer in certain epithelia. Yet, surprisingly little is known about the precise mechanisms responsible for assembly and disease pathology. In addition to these structural aspects of keratin function, experimental evidence accumulating in recent years has led to a much more complex view of the keratin cytoskeleton. Distinct keratins emerge as highly dynamic scaffolds in different settings and contribute to cell size determination, translation control, proliferation, cell type-specific organelle transport, malignant transformation and various stress responses. All of these properties are controlled by highly complex patterns of phosphorylation and molecular associations
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.
Nucleon-nucleon potential in finite nuclei
Yakhshiev, U. T.; Meißner, U. G.; Wirzba, A.; Rakhimov, A. M.; Musakhanov, M. M.
2004-01-01
We consider the spin-isospin-independent central part of the residual nucleon-nucleon potential in finite spherical nuclei taking into account the deformation effects of the nucleons within the surrounding nuclear environment. It is shown that inside the nucleus the short-range repulsive contribution of the potential is increased and the intermediate attraction is decreased. We identify the growth of the radial component of the spin-isospin independent short-range part of th...
Selected Topics in Three- and Four-Nucleon Systems
Kievsky, A
2011-01-01
Two different aspects of the description of three- and four-nucleon systems are addressed. The use of bound state like wave functions to describe scattering states in $N-d$ collisions at low energies and the effects of some of the widely used three-nucleon force models in selected polarization observables in the three- and four-nucleon systems are discussed.
Nucleon-nucleon theory and phenomenology
Signell, P.
Progress is outlined on five interrelated subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction with the new dramatically altered pi pi s wave interaction and using a new method taht unphysical region that lies between the pi N and physical regions of the N anti N yields i N and i physical regions of the N anti N yields pi (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly, and determining which phases are given by theory at which energies; (4) the introduction of our K-matrix formulation of the optimal polynomial expansion in order to accelerate convergence of the partial wave series at LAMPE energies; and (5) setting up of a cooperatively evaluated and verified permanent nucleon-nucleon data bank in the 0 to 1200 MeV range that can be used via Telenet dial in and by means of a published compendium.
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...
Drell-Yan Process and Nucleon Spin
International Nuclear Information System (INIS)
The role of the Drell-Yan process in studying nucleon spin is discussed. Recent results from the Fermilab E866 experiment on the angular distributions of Drell-Yan dimuons in p+p and p+d at 800 GeV/c are presented. These data are compared with the pion-induced Drell-Yan data, and with models which attribute the cos 2? azimuthal distribution to the presence of the transverse-momentum-dependent Boer-Mulders structure function h1perpendicular. Constraints on the magnitude of the sea-quark h1perpendicular structure functions are obtained. Future prospects for studying the TMDs with Drell-Yan experiments at Fermilab and J-PARC are also discussed.
Autotaxin: structure-function and signaling.
Perrakis, Anastassis; Moolenaar, Wouter H
2014-02-18
Autotaxin (ATX), or ecto-nucleotide pyrophosphatase/phosphodiesterase-2, is a secreted lysophospholipase D (lysoPLD) that hydrolyzes extracellular lysophospholipids into the lipid mediator lysophosphatidic acid (LPA), a ligand for specific G protein-coupled receptors. ATX-LPA signaling is essential for development and has been implicated in a great diversity of (patho)physiological processes, ranging from lymphocyte homing to tumor progression. Structural and functional studies have revealed what makes ATX a unique lysoPLD, and how secreted ATX binds to its target cells. The ATX catalytic domain shows a characteristic bimetallic active site followed by a shallow binding groove that can accommodate nucleotides as well as the glycerol moiety of lysophospholipids, and by a deep lipid-binding pocket. In addition, the catalytic domain has an open tunnel of unknown function adjacent to the active site. Here, we discuss our current understanding of ATX structure-function relationships and signaling mechanisms, and how ATX isoforms use distinct mechanisms to target LPA production to the plasma membrane, notably binding to integrins and heparan sulfate proteoglycans. We also briefly discuss the development of drug-like inhibitors of ATX. PMID:24548887
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 tf 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)
Direct observation of quark-hadron duality in the free neutron F_2 structure function
Niculescu, I; Melnitchouk, W; Arrington, J; Christy, M E; Ent, R; Griffioen, K A; Kalantarians, N; Keppel, C E; Kuhn, S; Tkachenko, S; Zhang, J
2015-01-01
Using data from the recent BONuS experiment at Jefferson Lab, which utilized a novel spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron F_2 structure function. The data are used to reconstruct the lowest few (N=2, 4 and 6) moments of F_2 in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark--hadron duality holds locally for the neutron in the second and third resonance regions down to Q^2 ~ 1 GeV^2, with violations possibly up to 20% observed in the first resonance region.
Pionic and Hidden-Color, Six-Quark Contributions to the Deuteron b1 Structure Function
Miller, Gerald A
2013-01-01
The b1 structure function is an observable feature of a spin-1 system sensitive to non-nucleonic components of the target nuclear wave function. The contributions of exchanged pions in the deuteron are estimated and found to be of measurable size for small values of x. A simple model for a hidden-color, six-quark configurations (with~ 0.15% probability to exist in the deuteron) is proposed and found to give substantial contributions for values of x>0.2. Good agreement with Hermes data is obtained. Predictions are made for an upcoming JLab experiment. The Close & Kumano sum rule is investigated and found to be a useful guide to understanding various possible effects that may contribute.
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
Orthogonality in nucleon knockout processes
International Nuclear Information System (INIS)
In the practical evaluation of exclusive inelastic processes, the difficulty of treating the continuum wave functions comes from the orthogonality defect arising from the inconsistent treatment of the initial and final state interactions. We propose to cure this lack of orthogonality, in the case of the plane wave approximation, by evaluating correction terms for large values of the momentum of the ejected nucleon
Measurement of Spin Structure Functions at Moderate Q2 Using CLAS
International Nuclear Information System (INIS)
Spin structure functions of the nucleon in the region of large z and small to moderate Q2 continue to be of high current interest. Among the topics one can study in this kinematic regime are spin-dependent resonance transition amplitudes and their interference with each other and the non-resonant background, the behavior of the asymmetry A1 at large x, and the presence or absence of local duality in spin structure functions. The first moment of the spin structure function g1 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. This opens up the possibility to study the transition from hadronic to quark degrees of freedom over the whole range of Q2. Recently, we concluded a large experimental program to measure these observables with polarized proton and deuteron targets at Jefferson Lab. A highly polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to accumulate over 23 billion events with 4 different beam energies of 1.6, 2.5, 4.2 and 5.7 GeV. We present an overview of the experiment, its kinematic coverage and its statistical power. We show final results from the first run at 2.5 GeV and 4 GeV and preliminary results from the 5.7 GeV and the 1.minary results from the 5.7 GeV and the 1.6 GeV data sets
Soudan 2 nucleon decay experiment
International Nuclear Information System (INIS)
The Soudan 2 nucleon decay experiment consists of a 1.1 Kton fine grained iron tracking calorimeter. It has a very isotropic detection structure which along with its flexible trigger will allow detection of multiparticle and neutrino proton decay modes. The detector has now entered its construction stage
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...
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
Pneumococcal Virulence Factors: Structure and Function
Jedrzejas, Mark J.
2001-01-01
The overall goal for this review is to summarize the current body of knowledge about the structure and function of major known antigens of Streptococcus pneumoniae, a major gram-positive bacterial pathogen of humans. This information is then related to the role of these proteins in pneumococcal pathogenesis and in the development of new vaccines and/or other antimicrobial agents. S. pneumoniae is the most common cause of fatal community-acquired pneumonia in the elderly and is also one of the...
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.)
Measuring structure functions at SSC energies
International Nuclear Information System (INIS)
Topics discussed include measuring ?, tests of QCD using hard scattering processes, and measuring parton distributions. In each case, any opportunities and advantages afforded by the unique features of the SSC are emphasized. The working group on structure functions was charged with investigating two specific questions: (1) How well are the various parton distributions known in the kinematic region relevant to calculations for the SSC. (2) What new information can be learned about parton distributions at the SSC. Especially for this working group, the advantages of having a fixed-target facility at the SSC for the measurement of the parton distributions with multi-TeV leptons, were to be examined. 15 references
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.
On hard pomeron enhancement of ultrahigh-energy neutrino-nucleon cross-sections
Berezinsky, Veniamin Sergeevich; Yanush, S I
2002-01-01
An unknown small-$x$ behavior of nucleon structure functions brings to appreciable uncertainties in high-energy neutrino-nucleon cross-sections. We show that Regge theory inspired description of $F_2^{ep}(x,Q^2)$ at small $x$ by \\emph{A. Donnachie and P. V. Landshoff}, comprising \\emph{'soft'} and \\emph{'hard'} pomeron terms, may be fairly combined with perturbative \\emph{QCD} parameterization at large $x$. We meet these descriptions over $\\log x$ at each $Q^2$ with help of simple polynomials, smooth interpolation being provided by an appropriate choice of interpolation zone boundaries. To express the low-$x$ neutrino-nucleon structure functions $F_{2}^{\
Nucleon sea parton densities. Differences for neutrinos and muons
International Nuclear Information System (INIS)
The nucleon sea parton distributions probed by muons and neutrinos are different since excitation of santi s, canti c pairs by muons and canti s, santi c pairs by neutrinos have different mass thresholds. Natural starting points for the structure functions are c?(x, Q2) ? s?(x, Q2), in ? (anti ?) interactions and c?(x, Q2)?(x, Q2) in ? interactions. Up to ?20% corrections to the conventional predictions for the neutrino structure functions at small x are predicted. The effects we discuss are in leading twist and persist numerically up to large values of Q2. (orig.)
International Nuclear Information System (INIS)
The calculation of longitudinal structure function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation in next-to-leading order (NLO) at small-x is presented. The calculation of FL is important for the phenomenological study of gluon distribution function inside the nucleon. Here we use Taylor Series Expansion method to solve the evolution equation for small-x and thus obtain t-evolution of FL structure function. The calculated results are compared with H1 and ZEUS data and results of Block and Donnachie-Landshoff (DL) models. (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.
Blast sampling for structural and functional analyses
Directory of Open Access Journals (Sweden)
Friedrich Anne
2007-02-01
Full Text Available Abstract Background The post-genomic era is characterised by a torrent of biological information flooding the public databases. As a direct consequence, similarity searches starting with a single query sequence frequently lead to the identification of hundreds, or even thousands of potential homologues. The huge volume of data renders the subsequent structural, functional and evolutionary analyses very difficult. It is therefore essential to develop new strategies for efficient sampling of this large sequence space, in order to reduce the number of sequences to be processed. At the same time, it is important to retain the most pertinent sequences for structural and functional studies. Results An exhaustive analysis on a large scale test set (284 protein families was performed to compare the efficiency of four different sampling methods aimed at selecting the most pertinent sequences. These four methods sample the proteins detected by BlastP searches and can be divided into two categories: two customisable methods where the user defines either the maximal number or the percentage of sequences to be selected; two automatic methods in which the number of sequences selected is determined by the program. We focused our analysis on the potential information content of the sampled sets of sequences using multiple alignment of complete sequences as the main validation tool. The study considered two criteria: the total number of sequences in BlastP and their associated E-values. The subsequent analyses investigated the influence of the sampling methods on the E-value distributions, the sequence coverage, the final multiple alignment quality and the active site characterisation at various residue conservation thresholds as a function of these criteria. Conclusion The comparative analysis of the four sampling methods allows us to propose a suitable sampling strategy that significantly reduces the number of homologous sequences required for alignment, while at the same time maintaining the relevant information concerning the active site residues.
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 goaltory's Genome and Beyond tactical goal
Structure, dynamics, and function of biomolecules
Energy Technology Data Exchange (ETDEWEB)
Frauenfelder, H.; Berendzen, J.R.; Garcia, A.; Gupta, G.; Olah, G.A.; Terwilliger, T.C.; Trewhella, J.; Wood, C.C.; Woodruff, W.H.
1998-11-01
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.
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
Summary of CDHS results on charged current in upsilon sup(-) -nucleon interactions
International Nuclear Information System (INIS)
This short review includes results on cross sections up to 300 GeV, a test of Callan - Gross relation, the determination of structure functions of the nucleon and the limit on right handed currents contribution. Conclusions from tests of QCD and non asymptotically free theories for strong interactions are presented. (author)
External Momentum, Volume Effects, and the Nucleon Magnetic Moment
Tiburzi, B C
2007-01-01
We analyze the determination of volume effects for correlation functions that depend on an external momentum. As a specific example, we consider finite volume nucleon current correlators, and focus on the nucleon magnetic moment. Because the multipole decomposition relies on SO(3) rotational invariance, the structure of such finite volume corrections is unrelated to infinite volume multipole form factors. One can deduce volume corrections to the magnetic moment only when a zero-mode photon coupling vanishes, as occurs at next-to-leading order in heavy baryon chiral perturbation theory. To deduce such finite volume corrections, however, one must assume continuous momentum transfer. In practice, volume corrections with momentum transfer dependence are required to address the extraction of the magnetic moment, or other observables that arise in momentum dependent correlation functions. Additionally we shed some light on a puzzle concerning differences in lattice form factor data at equal values of momentum trans...
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.
Proton structure functions in the dipole picture of BFKL dynamics
International Nuclear Information System (INIS)
The F2, FG, R = FL/FT proton structure functions are derived in the QCD dipole picture. Assuming kT factorization, we get a three parameter fit describing the 1994 H1 proton structure function F2 data in the low x, moderate Q2 range. Without any additional parameters, the gluon density and the longitudinal structure functions are predicted. (author)
International Nuclear Information System (INIS)
The Soudan nucleon decay program is being carried out in the Soudan iron mine in northeastern Minnesota, at a depth of 2000 m of water equivalent. A 30-ton prototype experiment, Soudan 1, has been built and is now being operated by a University of Minnesota - Argonne National Laboratory collaboration. The detector is a block of iron-loaded concrete instrumented with 3456 gas proportional tubes. It can detect nucleon decay at the 2 x 1030 year level, and will measure cosmic-ray induced backgrounds. Soudan 1 is also obtaining data on very high energy cosmic-ray interactions. Monte-Carlo predictions of performance have been checked by calibration of a detector module in a charged-particle test beam. A proposal to build a 1000-ton experiment, Soudan 2, has been submitted to funding agencies in the USA and the UK by a Minnesota - Argonne - Oxford University collaboration. The proposed detector utilizes drift chambers with 50-cm drifts to obtain very fine-grained ionization and tracking information at low cost. This tracking-calorimeter detector has a fiducial mass of 650 tons, and could be operating in 1985. A drifting scheme utilizing 50 cm x 5 m x 1 cm planar chambers has been shown feasible, and prototypes of alternate drifting structures are also being studied. A plan to provide expandability to an eventual 5000 tons has been developed
Overlap functions for reaction theories: challenges and open problems
International Nuclear Information System (INIS)
The overlap functions between the nuclear wave functions in initial and final states are important structural quantities that enter the amplitudes of nuclear reactions such as transfer, knockout and radiative capture. They carry information about the single-particle structure and about the nucleon–nucleon interactions and correlations in atomic nuclei. The current status of knowledge of overlap functions is reviewed with an emphasis on their theoretical calculation. The open problems associated with their prediction are highlighted and challenges are discussed. (paper)
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.
NuTeV structure function measurement
Energy Technology Data Exchange (ETDEWEB)
Tzanov, M.; /Pittsburgh U.
2005-07-01
The NuTeV experiment obtained high statistics samples of neutrino and antineutrino charged current events during the 1996-1997 Fermilab fixed target run. The experiment combines sign-selected neutrino and antineutrino beams and the upgraded CCFR iron-scintillator neutrino detector. A precision continuous calibration beam was used to determine the muon and hadron energy scales to a precision of 0.7% and 0.43% respectively. The structure functions F{sub 2}(x, Q{sup 2}) and xF{sub 3}(x, Q{sup 2}) obtained by fitting the y-dependence of the sum and the difference of the {nu} and {bar {nu}} differential cross sections are presented.
Structural and Functional Views of Mechatronic Products
DEFF Research Database (Denmark)
Nielsen, Kjeld; Petersen, Thomas Ditlev
2011-01-01
The development and subsequent production of industrial products are often complicated tasks. The complication increases with combined product as mechatronic products and is further complicated when large variety is required. Modularity is often used to achieve optimum in these complications both in the costumer view as well in the production view. In this paper, the relationships in mechatronic products between the functional and structural levels are explored in relation to modularity. A list of commonly used module drivers is presented and a qualitative survey is used to explore significance of influence on these module drivers when applying mechatronic product technology and view levels. The result is summarized in a list of which drivers should be addressed in a mechatronic product approach to modularity. Keywords:
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.
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.
Structure and functionality of bromine doped graphite
Energy Technology Data Exchange (ETDEWEB)
Hamdan, Rashid; Kemper, A. F.; Cao Chao; Cheng, H. P. [Department of Physics and Quantum Theory Project, University of Florida, Gainesville, Florida 32611 (United States)
2013-04-28
First-principles calculations are used to study the enhanced in-plane conductivity observed experimentally in Br-doped graphite, and to study the effect of external stress on the structure and functionality of such systems. The model used in the numerical calculations is that of stage two doped graphite. The band structure near the Fermi surface of the doped systems with different bromine concentrations is compared to that of pure graphite, and the charge transfer between carbon and bromine atoms is analyzed to understand the conductivity change along different high symmetry directions. Our calculations show that, for large interlayer separation between doped graphite layers, bromine is stable in the molecular form (Br{sub 2}). However, with increased compression (decreased layer-layer separation) Br{sub 2} molecules tend to dissociate. While in both forms, bromine is an electron acceptor. The charge exchange between the graphite layers and Br atoms is higher than that with Br{sub 2} molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.
Structure and functionality of bromine doped graphite
International Nuclear Information System (INIS)
First-principles calculations are used to study the enhanced in-plane conductivity observed experimentally in Br-doped graphite, and to study the effect of external stress on the structure and functionality of such systems. The model used in the numerical calculations is that of stage two doped graphite. The band structure near the Fermi surface of the doped systems with different bromine concentrations is compared to that of pure graphite, and the charge transfer between carbon and bromine atoms is analyzed to understand the conductivity change along different high symmetry directions. Our calculations show that, for large interlayer separation between doped graphite layers, bromine is stable in the molecular form (Br2). However, with increased compression (decreased layer-layer separation) Br2 molecules tend to dissociate. While in both forms, bromine is an electron acceptor. The charge exchange between the graphite layers and Br atoms is higher than that with Br2 molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.
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.
Measurements of the longitudinal structure function and |V{sub cs}| in the CCFR experiment
Energy Technology Data Exchange (ETDEWEB)
Yang, U.K. [and others
1998-07-01
Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F{sub 2}, xF{sub 3}{sup {nu}} , xF{sub 3}{sup {anti {nu}}} and R(longitudinal) in the kinematic region 0.01 < x < 0.6 and 1 < Q{sup 2} < 300 GeV{sup 2}. The new measurements of R in the x < 0.1 region provide a constraint on the level of the gluon distribution. The x and Q{sup 2} dependence of R is compared with a QCD based fit to previous data. The CKM matrix element {vert_bar}V{sub cs}{vert_bar} is extracted from a combined analysis of xF{sub 3} and dimuon data.
Moments of the proton F2 structure function at low Q2
International Nuclear Information System (INIS)
The authors review the status of inclusive electron-proton scattering F2 structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c)2. From these data they construct moments of F2, down to momentum transfers of Q2?0.1(GeV/c)2. The second moment is only slowly varying with Q2 down to Q2?1, which is a reflection of duality. Below Q2 of 1 (GeV/c)2, the Q2 dependence of the moments is predominantly governed by the elastic contribution, whereas the inelastic channels still seem governed by local duality
Moments of the proton F2 structure function at low Q2
International Nuclear Information System (INIS)
We investigate the Q2 dependence of inclusive electron-proton scattering F2 structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c)2. From these data we construct moments of F2, down to momentum transfers of Q2?0.1 (GeV/c)2. The second moment is only slowly varying with Q2 down to Q2?1 (GeV/c)2, which is a reflection of duality. Below Q2 of 1 (GeV/c)2, the Q2 dependence of the moments is predominantly governed by the elastic contribution, whereas the inelastic channels still seem governed by local duality
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)
Repulsive short-range three-nucleon interaction
International Nuclear Information System (INIS)
The three-nucleon interaction that is implied by the pion and the effective scalar and vector meson exchange components of the nucleon-nucleon interaction arises from the excitation of intermediate nucleon-antinucleon pairs. Using several wave-function models we show that this interaction is repulsive, reducing the calculated binding energy of the trinucleons by about 200--300 keV. The contributions of intermediate N(1440) resonances (and the same meson exchanges) to this three-nucleon interaction are also estimated and shown to be small
Measurement of the deuterium structure function A(q2) by electron scattering
International Nuclear Information System (INIS)
This work describes an electron scattering experiment on the deuterium nucleus. We were interested in the structure function A(q2) of this nucleus. This structure function is particularly sensitive to the nucleon-nucleon potential and to the neutron electric form factor. Cross sections have been measured at four incident energies: 200, 300, 500, 650 MeV and at scattering angles ranging from 300 to 1200. The momentum transfer range between q2 = 0.5 and q2 = 18 fm-2 was covered. Special care was given to the accuracy of the data. We have studied in detail all experimental corrections, in order to measure absolute cross sections. Most of our data have statistical errors smaller than 1%. The overall accuracy of our cross sections was confirmed by quasi-simultaneous measurements on a hydrogen target. These measurements were found to be in perfect agreement with a prediction computed using a fit to the world data on the electric and magnetic form factors of the proton. We have also measured cross sections for the deuteron electrodesintegration at threshold. These measurements together with cross sections measured previously at 1550 allow a separation of the longitudinal and transverse components of this process. The improved precision of our new data on the deuteron provide a stringent test for the presently available theoretical calculations. We have studied the sensitivity of A(q2) to different theoretical ingredients. We have also shown that within some assumptions, our measurements permit a raisonable estimation of the uncertainty on the neutron electric form factor
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
Soil-Borne Microbial Functional Structure across Different Land Uses
Kuramae, Eiko E.; Zhou, Jizhong Z.; Kowalchuk, George A.; Veen, Johannes A.
2014-01-01
Land use change alters the structure and composition of microbial communities. However, the links between environmental factors and microbial functions are not well understood. Here we interrogated the functional structure of soil microbial communities across different land uses. In a multivariate regression tree analysis of soil physicochemical properties and genes detected by functional microarrays, the main factor that explained the different microbial community functional structures was C...
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.
Nucleon Magnetic Moments and Electric Polarizabilities
Energy Technology Data Exchange (ETDEWEB)
W Detmold, B C Tiburzi, A Walker-Loud
2010-06-01
Electromagnetic properties of the nucleon are explored with lattice QCD using a novel technique. Focusing on background electric fields, we show how the electric polarizability can be extracted from nucleon correlation functions. A crucial step concerns addressing contributions from the magnetic moment, which affects the relativistic propagation of nucleons in electric fields. By properly handing these contributions, we can determine both magnetic moments and electric po larizabilities. Lattice results from anisotropic clover lattices are presented. Our method is not limited to the neutron; we show results for the proton as well.
Li, Bing An
2014-01-01
The study of electromagnetic and weak form factors of nucleon (charged quasielastic scatterings of neutrino (antineutrino) and nucleon) done in $70^\\prime s$ and published in Chinese journals is reviewed. In the approach of the study antiquark components are introduced to the wave functions of nucleon and the study shows that the antiquark components of nucleon play an essential role in the EM and weak form factors of nucleon. The SU(6) symmetric wave functions of baryons in the rest frame ( s-wave in the rest frame) have been constructed. In these wave functions there are both quark and antiquark components. Using Lorentz transformations these wave functions are boosted to moving frame. In terms of effective Lagrangian these wave functions are used to study the EM and weak form factors of nucleon and $p \\rightarrow \\Delta$. The ratio $\\mu_p G^p_E/G^p_M$, $G^n_E$, $G^n_M$, $G^*_M$, $E1+$ and $S1+$ of $p \\rightarrow \\Delta$ are predicted. The axial-vector form factors of nucleon is predicted to be $G_A(q^2)/G_...
A functional-structural model for growth of clonal bunchgrasses
Tomlinson, K. W.; Dominy, J. G.; Hearne, J. W.; O Connor, T. G.
2007-01-01
Interactions between structural architecture and resource allocation affect the ability of plants to utilise environmental resources. Architecture defines the structural layout and relationships of organs and other structural units at different hierarchical levels in plants. Resource allocation determines how competing structural units are awarded resources at different levels of hierarchy. Functional-structural plant models combine architecture and resource allocation as interacting componen...
Orbital angular momentum in the nucleons
Lorcé, Cédric
2014-01-01
In the last decade, it has been realized that the orbital angular momentum of partons inside the nucleon plays a major role. It contributes significantly to nucleon properties and is at the origin of many asymmetries observed in spin physics. It is therefore of paramount importance to determine this quantity if we want to understand the nucleon internal structure and experimental observables. This triggered numerous discussions and controversies about the proper definition of orbital angular momentum and its extraction from experimental data. We summarize the present situation and discuss recent developments in this field.
Study of the compressibility of the nucleon
International Nuclear Information System (INIS)
A brief discussion of the theoretical and experimental situation in baryon spectroscopy is given. Then, the radial structure is discussed, related to the ground state form factors and the compressibility. The compressibility derived from experimental data is compared with results from different nucleon models. From the study of the Roper resonance in nuclei information on the dynamical radius of the nucleon can be obtained. Experiments have been performed on deuteron and 12C which show no shift of the Roper resonance in these systems. This indicates no sizeable 'swelling' or 'shrinking' of the nucleon in the nuclear medium. (K.A.)
Structure and function of eukaryotic chromosomes
Energy Technology Data Exchange (ETDEWEB)
Hennig, W.
1987-01-01
Contents: Introduction; Polytene Chromosomel Giant Chromosomes in Ciliates; The sp-I Genes in the Balbiani Rings of Chironomus Salivary Glands; The White Locus of Drosophila Melanogaster; The Genetic and Molecular Organization of the Dense Cluster of Functionally Related Vital Genes in the DOPA Decarboxylase Region of the Drosophila melanogaster Genome; Heat Shock Puffs and Response to Environmental Stress; The Y Chromosomal Lampbrush Loops of Drosophila; Contributions of Electron Microscopic Spreading Preparations (''Miller Spreads'') to the Analysis of Chromosome Structure; Replication of DNA in Eukaryotic Chromosomes; Gene Amplification in Dipteran Chromosomes; The Significance of Plant Transposable Elements in Biologically Relevant Processes; Arrangement of Chromosomes in Interphase Cell Nuclei; Heterochromatin and the Phenomenon of Chromosome Banding; Multiple Nonhistone Protein-DNA Complexes in Chromatin Regulate the Cell- and Stage-Specific Activity of an Eukaryotic Gene; Genetics of Sex Determination in Eukaryotes; Application of Basic Chromosome Research in Biotechnology and Medicine. This book presents an overview of various aspects of chromosome research.
Polarized light ions and spectator nucleon tagging at EIC
Guzey, V; Hyde, Ch; Nadel-Turonski, P; Park, K; Sargsian, M; Strikman, M; Weiss, C
2014-01-01
An Electron-Ion Collider (EIC) with suitable forward detection capabilities would enable a unique experimental program of deep-inelastic scattering (DIS) from polarized light nuclei (deuterium 2H, helium 3He) with spectator nucleon tagging. Such measurements promise significant advances in several key areas of nuclear physics and QCD: (a) neutron spin structure, by using polarized deuterium and eliminating nuclear effects through on-shell extrapolation in the spectator proton momentum; (b) quark/gluon structure of the bound nucleon at x > 0.1 and the dynamical mechanisms acting on it, by measuring the spectator momentum dependence of nuclear structure functions; (c) coherent effects in QCD, by exploring shadowing in tagged DIS on deuterium at x << 0.1. The JLab MEIC design (CM energy sqrt{s} = 15-50 GeV/nucleon, luminosity ~ 10^{34} cm^{-2} s^{-1}) provides polarized deuterium beams and excellent coverage and resolution for forward spectator tagging. We summarize the physics topics, the detector and bea...
Parton content of the nucleon from distribution amplitudes and transition distribution amplitudes
Pasquini, B.; Pincetti, M.; Boffi, S.
2009-01-01
The nucleon distribution amplitudes and the nucleon-to-pion transition distribution amplitudes are investigated at leading twist within the frame of a light-cone quark model. The distribution amplitudes probe the three-quark component of the nucleon light-cone wave function, while higher order components in the Fock-space expansion of the nucleon state are essential to describe the nucleon-to-pion transition distribution amplitudes. Adopting a meson-cloud model of the nucleo...
Directory of Open Access Journals (Sweden)
Aparajita Bhattacharya
2011-02-01
Full Text Available The modification of the properties of nucleon in nuclear medium has been investigated in the context of flux tube model. A nucleon has been described as diquark-quark system connected by flux tube and quasi particle diquark model has been used to describe the diquak constituting the nucleon. The modification of incompressiblity, the Roper resonance etc in the nuclear medium have been investigated. The results are compared with recent experimental and theoretical predictions. Some interesting observations are made.
International Nuclear Information System (INIS)
We present results on inelastic J/? production from muon interactions with hydrogen and deuterium at an incident muon energy of 280 GeV. The measured cross section ratio per nucleon for muon-induced J/? production in deuterium and hydrogen was found to be R(D2/H2)=1.01±0.15. The colour singlet model is shown to provide a good description of the observed differential cross section apart from a normalisation factor. The comparison between the observed cross section and the colour singlet model prediction allows the extraction of the gluon structure function G(?) of the nucleon. The momentum fraction ? of the nucleon carried by the gluon is measured in the range of ?=[0.02,0.30]. The normalised gluon distribution of free nucleons thus found can be parametrised as ?G(?)=1/2(?+1)(1-?)?, with ?=5.1±0.9(stat.). (orig.)
Extraction of nucleon momentum distributions from inclusive electron scattering on nuclei
Rinat, A. S.; Taragins, M. F.
1999-01-01
We address the problem of extracting single-nucleon momentum distributions $n(p)$ from inclusice scattering data. A model for these relates nuclear and nucleon structure functions (SF) through an intermediate SF $f^{PN}$ for a nucleus of point-particles. In addition to the asymptotic limit (AL) which depends on $n(p), f^{PN}$ contains, generally $q$-dependent Final State Interactions (FSI) parts. In the inverse problem one wishes to separate $q$-dependent FSI from the AL. In...