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
Nucleon structure functions from constituent quark
Khorramian, Ali N.; Arash, Firooz
1999-10-01
We have used a constituent quarks model to describe the nucleon structure function, F2( χ, Q2), for a wide range of χ=[10 -6,1] and Q2 = [0.5, 5000] GeV2. We have found that although F2 rises as χ decreases, but there exists some χ0 ≤ 10 -4 - 10 -5, below which the rise of F2 subsides drastically and hence, exhibits an almost flat behavior, compatible with the latest results from HERA, at least for low Q2.
Nucleon structure functions in noncommutative space-time
Rafiei, Ali; Mirjalili, Abolfazl
2016-01-01
In the context of noncommutative space-time, we investigate the nucleon structure functions which plays an important role to identify the internal structure of nucleons. We use the corrected vertices and employ new vertices that appear in two approaches of noncommutativity and calculate the proton structure functions in terms of noncommutative tensor \\theta_{\\mu\
Nucleon structure functions from relativistic constituent quarks
Melnitchouk, W
1994-01-01
We investigate deep inelastic lepton scattering from the nucleon within a constituent quark picture, in which the internal structure of constituent quarks is modeled by meson and diquark dressing. In a covariant framework this structure leads to a breakdown of the factorization necessary for a convolution formulation. We perform our analysis in time-ordered perturbation theory in the infinite momentum frame where factorization of subprocesses is automatic. Numerical results are compared with recent data on valence quark distributions in the proton.
A no extensive statistical model for the nucleon structure function
Trevisan, Luis A.; Mirez, Carlos
2013-03-01
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.
a Nonextensive Statistical Model for the Nucleon Structure Function
Trevisan, Luis Augusto; Mirez, Carlos
2013-07-01
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalizations in the nucleon.
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.
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.
A model for nucleon, pion and kaon 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 Q20 at which hadrons are pure valence quark (or antiquark) bound states leads to definite predictions on their structure functions. Predictions are made here using a non-relativistic approximation for the bound states. Good agreement with experiment is found for nucleon, pion and kaon structure functions
In Medium Nucleon Structure Functions, SRC, and the EMC effect
Hen, O; Gilad, S; Wood, S A
2014-01-01
A proposal approved by the Jefferson Lab PAC to study semi-inclusive deep inelastic scattering (DIS) off the deuteron, tagged with high momentum recoiling protons or neutrons emitted at large angle relative to the momentum transfer. This experiment aims at studying the virtuality dependence of the bound nucleon structure function as a possible cause to the EMC effect and the EMC-SRC correlations. The experiment was approved in 2011 for a total run time of 40 days.
Nuclear effects in F_3 structure function of nucleon
Athar, M Sajjad; Vacas, M J Vicente
2007-01-01
We study nuclear effects in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio $R(x,Q^2)=\\frac{F^A_3(x,Q^2)}{AF^N_3(x, Q^2)}$ and the Gross-Llewellyn Smith(GLS) integral $G(x,Q^2)=\\int_x^1 dx F^A_3(x,Q^2)$ in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.
Nucleon effective mass and the A dependence of structure functions
Energy Technology Data Exchange (ETDEWEB)
Garcia Canal, C.A.; Santangelo, E.M.; Vucetich, H.
1984-10-08
The nucleon effective mass was successfully used, as the only free parameter, to adjust the ratio R(A) of structure functions measured in a nucleus of mass number A and in the deuteron, for each A value in the SLAC set of experimental data. The resulting A dependence of the effective mass, being linear in A/sup -1/3/, is consistent with the behavior expected from nuclear structure considerations. The extrapolated value of the effective mass for nuclear matter agrees with previous estimations.
Neutrinos and nucleon structure
Sehgal, L M
1979-01-01
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. The author attempts a critical appraisal of recent facts and their impact on our theoretical understanding. (35 refs).
Polarized Structure Function of Nucleon and Orbital Angular Momentum
Arash, Firooz; Taghavi-Shahri, Fatemeh
2007-06-01
We have utilized the concept of valon model to calculate the spin structure function of a constituent quark. This structure is universal and arises from perturbative dressing of a valence quark in QCD. With a convolution method the polarized structure functions of proton, neutron, and deuteron are obtained. Our results agree rather well with all available experimental data. It suggests that the sea quark contribution to the spin of nucleon is consistent with zero, in agreement with HERMES data. It also reveals that while the total quark contribution to the spin of a constituent quark, or valon, is almost constant and equal to one, the gluon contribution grows with the increase of Q2, and hence, requiring a sizable negative angular momentum contribution. This component, as well as singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD. We speculate that the gluon contribution to the spin of proton is in the order of 50%. Furthermore, we have determined the polarized valon distribution in a nucleon.
Structure functions of the nucleon and nuclei in neutrino reactions
International Nuclear Information System (INIS)
Determination of parton distribution functions in nuclei is important for calculating nuclear corrections in oscillation experiments, from which detailed information should be extracted on neutrino properties. First, nuclear parton distributions are discussed for explaining high-energy nuclear reaction data. Possible nuclear modification is explained for valence-quark and antiquark distributions. It is rather difficult to determine gluon distributions in nuclei. Next, reversing the topic, we discuss structure functions which could be investigated by neutrino reactions. Determination of polarized parton distributions in the nucleon is discussed in polarized neutrino reactions. In addition, neutrino reactions should be important for finding nuclear modification of valence-quark distributions at small x if structure function ratios F3A/F3D are measured for various nuclei
Nucleon Structure Function F2 in the Resonance Region and Quark-Hadron Duality
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing; LI Ming-Fei
2003-01-01
Based on a simple nonrelativistic constituent quark model, the nucleon structure function F2 in theresonance region is estimated by taking the contributions from low-lying nucleon resonances into account. Calculatedresults are employed to study quark-hardon duality in the nucleon electron scattering process by comparing them to thescaling behavior from the data in deep inelastic scattering region.
Chiral Quark Soliton Model and Nucleon Spin Structure Functions
Wakamatsu, M
2009-01-01
The chiral quark soliton model (CQSM) is one of the most successful models of baryons at quark level, which maximally incorporates the most important feature of low energy QCD, i.e. the chiral symmetry and its spontaneous breakdown. Basically, it is a relativistic mean-field theory with full account of infinitely many Dirac-sea quarks in a rotational-symmetry-breaking mean field of hedgehog shape. The numerical technique established so far enables us to make a nonperturbative evaluation of Casimir effects (i.e. effects of vacuum-polarized Dirac sea) on a variety of baryon observables. This incompatible feature of the model manifests most clearly in its predictions for parton distribution functions of the nucleon. In this talk, after briefly reviewing several basic features of the CQSM, we plan to demonstrate in various ways that this unique model of baryons provides us with an ideal tool for disentangling nonperturbative aspect of the internal partonic structure of the nucleon, especially the underlying spin ...
Detailed Measurements of Structure Functions from Nucleons and Nuclei
2002-01-01
The experiment will study deep inelastic muon nucleon scattering in a wide range of Q|2~(1-200 (GeV/c)|2) and x~(0.005-0.75). The main aims of the experiment are: \\item a)~~~~Detailed measurements of the nuclear dependence of the structure function F^2|A, of R~=~@s^L/@s^T and of the cross-section for J/@y production. They will provide a basis for the understanding of the EMC effect: the modification of quark and gluon distributions due to the nuclear environment. \\item b)~~~~A simultaneous high luminosity measurement of the structure function F^2 on hydrogen and deuterium. This will provide substantially improved accuracy in the knowledge of the neutron structure function F^2|n, of F^2|p-F^2|n and F^2|n/F^2|p and their Q|2 dependence. Furthermore, the data will allow a determination of the strong coupling constant @a^s(Q|2) with reduced experimental and theoretical uncertainties as well as of the ratio of the down to up quark distributions in the valence region. Due to the large x range covered by the experim...
Measurement of the nucleon structure function using high energy muons
International Nuclear Information System (INIS)
We have measured the inclusive deep inelastic scattering of muons on nucleons in iron using beams of 93 and 215 GeV muons. To perform this measurement, we have built and operated the Multimuon Spectrometer (MMS) in the muon beam at Fermilab. The MMS is a magnetized iron target/spectrometer/calorimeter which provides 5.61 kg/cm2 of target, 9% momentum resolution on scattered muons, and a direct measure of total hadronic energy with resolution sigma/sub nu/ = 1.4√nu(GeV). In the distributed target, the average beam energies at the interaction are 88.0 and 209 GeV. Using the known form of the radiatively-corrected electromagnetic cross section, we extract the structure function F2(x,Q2) with a typical precision of 2% over the range 5 2 2/c2. We compare our measurements to the predictions of lowest order quantum chromodynamics (QCD) and find a best fit value of the QCD scale parameter Λ/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
Nucleon Spin Structure Functions in the Resonance Region and the Duality
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing; FENG Qing-Guo
2003-01-01
We discuss the nucleon spin structure function gl and the difference between the proton and neutrontargets gp1 - gn1 , based on quark model calculation. Quark-hadron duality for the nucleon spin structure function is alsoanalyzed. Effects of the △(1232) and Roper P11(1440) resonances on the spin structure function and on the differencegn1 - gn1 are mentioned. The results of different models for the Roper resonance are also addressed.
Measurement of the nucleon structure function using high energy muons
Energy Technology Data Exchange (ETDEWEB)
Meyers, P.D.
1983-12-01
We have measured the inclusive deep inelastic scattering of muons on nucleons in iron using beams of 93 and 215 GeV muons. To perform this measurement, we have built and operated the Multimuon Spectrometer (MMS) in the muon beam at Fermilab. The MMS is a magnetized iron target/spectrometer/calorimeter which provides 5.61 kg/cm/sup 2/ of target, 9% momentum resolution on scattered muons, and a direct measure of total hadronic energy with resolution sigma/sub nu/ = 1.4..sqrt..nu(GeV). In the distributed target, the average beam energies at the interaction are 88.0 and 209 GeV. Using the known form of the radiatively-corrected electromagnetic cross section, we extract the structure function F/sub 2/(x,Q/sup 2/) with a typical precision of 2% over the range 5 < Q/sup 2/ < 200 GeV/sup 2//c/sup 2/. We compare our measurements to the predictions of lowest order quantum chromodynamics (QCD) and find a best fit value of the QCD scale parameter ..lambda../sub LO/ = 230 +- 40/sup stat/ +- 80/sup syst/ MeV/c, assuming R = 0 and without applying Fermi motion corrections. Comparing the cross sections at the two beam energies, we measure R = -0.06 +- 0.06/sup stat/ +- 0.11/sup syst/. Our measurements show qualitative agreement with QCD, but quantitative comparison is hampered by phenomenological uncertainties. The experimental situation is quite good, with substantial agreement between our measurements and those of others. 86 references.
The polarized structure function of the nucleons with a non-extensive statistical quark model
Trevisan, Luis A.; Mirez, Carlos
2013-05-01
We studied an application of nonextensive thermodynamics to describe the polarized structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution, often used in the statistical models, were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and the chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon and by Δu and Δd of the polarized functions.
International Nuclear Information System (INIS)
Generalized parton distributions provide information on the longitudinal and transverse distribution of partons in the fast moving nucleon. Furthermore, they contain information on the spin structure of the nucleon. First results of a lattice study of generalized parton distributions are presented. (orig.)
International Nuclear Information System (INIS)
Within the framework of quenched lattice QCD and using O(a) improved Wilson fermions and nonperturbative renormalization, a high statistics computation of low moments of the unpolarized nucleon structure functions is given. Particular attention is paid to the chiral and continuum extrapolations
International Nuclear Information System (INIS)
Within the framework of quenched lattice QCD and using O(a) improved Wilson fermions and non-perturbative renormalisation, a high statistics computation of low moments of the unpolarised nucleon structure functions is given. Particular attention is paid to the chiral and continuum extrapolations. (orig.)
Bloom-Gilman Duality of Nucleon Spin Structure Function and Elastic Peak Contribution
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing
2005-01-01
By employing the parametrization form of the nucleon spin structure function in the resonance region,which includes the contributions of the resonance peaks and of nonresonance background, we study Bloom-Gilman quark-hadron duality of g1 both in the inelastic resonance region and elastic one.
Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons
Energy Technology Data Exchange (ETDEWEB)
Bodek, Arie [University of Rochester, Rochester, NY
2015-09-01
We present preliminary results on an experimental study of the nuclear modification of the longitudinal (σ_{L}) and transverse (σ_{T}) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= σ_{L}/σ_{T} for nuclei (R_{A}) and for deuterium (RD) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, R_{A} < R_{D}.
Nejad, S. Mohammad Moosavi; Khanpour, Hamzeh; Tehrani, S. Atashbar; Mahdavi, Mahdi
2016-10-01
We present a detailed QCD analysis of nucleon structure functions x F3(x ,Q2) , based on Laplace transforms and the Jacobi polynomials approach. The analysis corresponds to the next-to-leading order and next-to-next-to-leading order approximations of perturbative QCD. The Laplace transform technique, as an exact analytical solution, is used for the solution of nonsinglet Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations at low- and large-x values. The extracted results are used as input to obtain the x and Q2 evolution of x F3(x ,Q2) structure functions using the Jacobi polynomials approach. In our work, the values of the typical QCD scale ΛMS¯ (nf) and the strong coupling constant αs(MZ2) are determined for four quark flavors (nf=4 ) as well. A careful estimation of the uncertainties shall be performed using the Hessian method for the valence-quark distributions, originating from the experimental errors. We compare our valence-quark parton distribution functions sets with those of other collaborations, in particular with the CT14, MMHT14, and NNPDF sets, which are contemporary with the present analysis. The obtained results from the analysis are in good agreement with those from the literature.
Measurement of nucleon structure function in muon scattering at high q2
International Nuclear Information System (INIS)
The nucleon structure function, F2, has been measured up to q2 = 120 (GeV/c)2 and for 40 2 2. The data exhibit a significant pattern of scaling violation. Compared to lower-energy data, F2 shows an observable increase of approx. 15% at high q2 for x < 0.4. The pattern of the increase may accommodate a threshold in W or new theoretical parametrizations
Spin structure functions of the nucleon at low Q{sup 2} and {nu}
Energy Technology Data Exchange (ETDEWEB)
Burkert, V.D.
1993-06-30
Phenomenological approaches to describe the spin structure functions an spin sum rules for proton and neutrons at low momentum transfer Q{sup 2} and energy transfer {nu}, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A{sub 1}{sup p}, A{sub 2}{sup p} and N{sub 1}{sup n} structure functions at CEBAF in a Q{sup 2} range from 0.15 to 2.0 GeV{sup 2}, and a W range from threshold to 2.2 GeV are presented.
A two component model describing nucleon structure functions in the low-x region
Energy Technology Data Exchange (ETDEWEB)
Bugaev, E.V. [Institute for Nuclear Research of the Russian Academy of Sciences, 7a, 60th October Anniversary prospect, Moscow 117312 (Russian Federation); Mangazeev, B.V. [Irkutsk State University, 1, Karl Marx Street, Irkutsk 664003 (Russian Federation)
2009-12-15
A two component model describing the electromagnetic nucleon structure functions in the low-x region, based on generalized vector dominance and color dipole approaches is briefly described. The model operates with the mesons of rho-family having the mass spectrum of the form m{sub n}{sup 2}=m{sub r}ho{sup 2}(1+2n) and takes into account the nondiagonal transitions in meson-nucleon scattering. The special cut-off factors are introduced in the model, to exclude the gamma-qq-bar-V transitions in the case of narrow qq-bar-pairs. For the color dipole part of the model the well known FKS-parameterization is used.
Progress towards a lattice determination of (moments of) nucleon structure functions
International Nuclear Information System (INIS)
Using unimproved and non-perturbatively O(a) improved Wilson fermions, results are given for the three lowest moments of unpolarised nucleon structure functions. Renormalisation, chiral extrapolation and the continuum limit of the matrix elements are briefly discussed. The simulations are performed for both quenched and two flavours of unquenched fermions. No obvious sign of deviation from linearity in the chiral extrapolations are found. (This is most clearly seen in our quenched unimproved data, which extends to lighter quark mass). Possible quenching effects also seem to be small. The lowest moment thus remains too large, so it seems to be necessary to reach smaller quark masses in numerical simulations. (orig.)
Gold-plated moments of nucleon structure functions in baryon chiral perturbation theory
Lensky, Vadim; Pascalutsa, Vladimir
2014-01-01
We obtain leading- and next-to-leading order predictions of chiral perturbation theory for several prominent moments of nucleon structure functions. These free-parameter free results turn out to be in overall agreement with the available empirical information on all of the considered moments, in the region of low-momentum transfer ($Q^2 < 0.3$ GeV$^2$). Especially surprising is the situation for the $\\delta_{LT}$ moment, which thus far was not reproducible for proton and neutron simultaneously in chiral perturbation theory. This problem, known as the "$\\delta_{LT}$ puzzle," is not seen in the present calculation.
Nucleon structure from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Dinter, Simon
2012-11-13
In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a{sup 2}) discretization effects.
Nucleon structure from lattice QCD
International Nuclear Information System (INIS)
In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a2) discretization effects.
Nuclear effects in F{sub 3} structure function of nucleon
Energy Technology Data Exchange (ETDEWEB)
Athar, M. Sajjad [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India)], E-mail: sajathar@rediffmail.com; Singh, S.K. [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Vacas, M.J. Vicente [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, 46100 Burjassot (Valencia) (Spain)
2008-10-02
We study nuclear effects in the F{sub 3}{sup A}(x) structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio R(x,Q{sup 2})=(F{sub 3}{sup A}(x,Q{sup 2}))/(AF{sub 3}{sup N}(x,Q{sup 2})) and the Gross-Llewellyn Smith (GLS) integral G(x,Q{sup 2})={integral}{sub x}{sup 1}dxF{sub 3}{sup A}(x,Q{sup 2}) in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.
Indian Academy of Sciences (India)
N Barik; R N Mishra
2001-04-01
Considering the nucleon as consisting entirely of its valence quarks conﬁned independently in a scalar-vector harmonic potential; unpolarized structure functions 1(,2) and 2(x,2) are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions (,2) and (,2) are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of 2=0.07 GeV2 to a higher $Q^{2}$ scale of $Q^{2}_{0} = 15$ GeV2 yields (, $Q^{2}_{0}$) and (, $Q^{2}_{0}$) in good agreement with experimental data. The gluon and sea-quark distributions such as (,$Q^{2}_{0}$) and (, $Q^{2}_{0}$) are dynamically generated with a reasonable qualitative agreement with the available data; using the leading order renormalization group equations with appropriate valence-quark distributions as the input.
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.
Nucleon structure functions and longitudinal spin asymmetries in the chiral quark constituent model
Dahiya, Harleen; Randhawa, Monika
2016-06-01
We have analyzed the phenomenological dependence of the spin independent (F1p ,n and F2p ,n) and the spin dependent (g1p ,n) structure functions of the nucleon on the Bjorken scaling variable x using the unpolarized distribution functions of the quarks q (x ) and the polarized distribution functions of the quarks Δ q (x ) respectively. The chiral constituent quark model, which is known to provide a satisfactory explanation of the proton spin crisis and related issues in the nonperturbative regime, has been used to compute explicitly the valence and sea quark flavor distribution functions of p and n . In light of the improved precision of the world data, the p and n longitudinal spin asymmetries [A1p(x ) and A1n(x )] have been calculated. The implication of the presence of the sea quarks has been discussed for the ratio of polarized to unpolarized quark distribution functions for up and down quarks in the p and n Δ/up(x ) up(x ) , Δ/dp(x ) dp(x ) , Δ/un(x ) un(x ) , and Δ/dn(x ) dn(x ) . The ratio of the n and p structure functions Rn p(x )=F/2n(x ) F2p(x ) has also been presented. The results have been compared with the recent available experimental observations. The results on the spin sum rule have also been included and compared with data and other recent approaches.
Tests of perturbative QCD using CCFR data for measurements of nucleon structure functions
Energy Technology Data Exchange (ETDEWEB)
Bodek, A.; Budd, H.S.; De Barbaro, P.; Sakumoto, W.K.; Leung, W.C.; Quintas, P.Z.; Sciulli, F.; Arroyo, C.; Bachmann, K.T.; Blair, R.E.; Foudas, C.; King, B.J.; Lefmann, W.C.; Mishra, S.R.; Oltman, E.; Rabinowitz, S.A.; Seligman, W.G.; Shaevitz, M.H.; Merritt, F.S.; Oreglia, M.J.; Schumm, B.A.; Bernstein, R.H.; Borcherding, F.; Fisk, H.E.; Lamm, M.J.; Marsh, W.; Merritt, K.W.B.; Schellman, H.; Yovanovitch, D.D.; Sandler, P.H.; Smith, W.H. (Univ. of Rochester, NY (United States) Columbia Univ., New York, NY (United States) Univ. of Chicago, IL (United States) Fermilab, Batavia, IL (United States) Univ. of Wisconsin, Madison, WI (United States))
1993-04-01
We present measurements of nucleon structure functions, F[sub 2](x, Q[sup 2]) and xF[sub 3](x, Q[sup 2]), from the high-statistics, high-energy neutrino-iron scattering experiment at the Fermilab Tevatron. The existing high-statistics xF[sub 3] determination by the CDHSW collaboration is compared to our data. The data presented here constitute the first corroboration of the QCD prediction of xF[sub 3] evolution at low-x, and yields [Lambda][anti M][anti S] = 210 [+-] 28 [+-] 41 MeV, and a determination of the GLS sum rule at Q[sup 2] = 3 GeV[sup 2], S[sub GLS] = [integral][sup 1][sub x] xF[sub 3]/x dx = 2.50 [+-] 0.018(stat.) [+-]0.078 (syst.). Our value of [Lambda][anti M][anti S] yields [alpha][sub s](M[sub z]) = .111 [+-] .002 [+-] .003 [+-] .003 (scale). Comparison of the neutrino determination of F[sub 2](x, Q[sup 2]) with that obtained from the charged-lepton (e or [mu]) scattering leads to a precise test of the mean-square charge prediction by the Quark Parton Model. The SLAC-CCFR and BCDMS structure function provide a consistent and precise set of structure functions over a large range of Q[sup 2]. (orig.)
Nucleon structure functions and longitudinal spin asymmetries in the chiral quark constituent model
Dahiya, Harleen
2016-01-01
We have analysed the phenomenological dependence of the spin independent ($F_1^{p,n}$ and $F_2^{p,n}$) and the spin dependent ($g_1^{p,n}$) structure functions of the nucleon on the the Bjorken scaling variable $x$ using the unpolarized distribution functions of the quarks $q(x)$ and the polarized distribution functions of the quarks $\\Delta q(x)$ respectively. The chiral constituent quark model ($\\chi$CQM), which is known to provide a satisfactory explanation of the proton spin crisis and related issues in the nonperturbative regime, has been used to compute explicitly the valence and sea quark flavor distribution functions of $p$ and $n$. In light of the improved precision of the world data, the $p$ and $n$ longitudinal spin asymmetries ($A_1^p(x)$ and $A_1^n(x)$) have been calculated. The implication of the presence of the sea quarks has been discussed for ratio of polarized to unpolarized quark distribution functions for up and down quarks in the $p$ and $n$ $\\frac{\\Delta u^p(x)}{u^p(x)}$, $\\frac{\\Delta d...
Study of the nucleon spin structure functions: the E154 experiment at SLAC
International Nuclear Information System (INIS)
In experiment E154 at SLAC, the spin dependent structure function g1n was measured by scattering longitudinally polarized 50 GeV electrons off a longitudinally polarized helium 3 target. We report the integral over the measured x range to be ∫0.0140.7g1n(x,5 GeV2)dx = -0.0348 ± 0.0033 ± 0.0043 ± 0.0014. We observe relatively large values of g1n at low x, calling into question the reliability of the data extrapolation down to x equal 0. Such a divergent behavior seems to disagree with the prediction of the Regge theory but can be quantitatively explained by perturbative QCD. Moreover, we have performed a NLO perturbative QCD analysis of the world data on g1, paying careful attention to both the theoretical hypothesis and the calculation of errors. Using a parametrization of the polarized parton distribution at a low scale, we can access the fraction of spin carried by quarks: ΔΣ = 29 ± 6 pc in the MS-bar scheme, and ΔΣ = 37 ± 7 pc in the AB scheme. The gluon contribution to the nucleon spin is not well enough constrained by the current data, but seems to lie between 0 and 2. This study allows us to extract the first moment of the g1 structure function and we find agreement with the Bjorken sum rule expectations. (author)
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.
Kotlorz, Dorota
2008-01-01
Predictions for the spin dependent structure function $g_1$ of the nucleon are presented. We use an unified approach incorporating the LO DGLAP evolution and the resummation of double logarithmic terms $ln^2(x)$. We show, that the singular input parametrisation as $x\\to 0$ can be a substitute of the $ln^2(x)$ resummation. An impact of the `more running' coupling is discussed. We determine the contribution to the Bjorken sum rule solving the evolution equation for the truncated moment of $g_1^{NS}$. A comparison with the re-analysed HERMES and COMPASS data is given.
Constituent quark description of nucleon structure
International Nuclear Information System (INIS)
Nucleon structure functions are calculated within the constituent quark in the leading order. The results compare well with the experimental data for entire range of kinematics in x and Q2and with the next - to - leading order calculation of GRV
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.
Analysis of DIS structure functions of the nucleon within truncated Mellin moments approach
Kotlorz, D
2016-01-01
We present generalized evolution equations and factorization in terms of the truncated Mellin moments (TMM) of the parton distributions and structure functions. We illustrate the $x$ and $Q^2$ dependence of TMM in the polarized case. Using the TMM approach we compare the integrals of $g_1$ with HERMES and COMPASS data from the limited $x$-ranges.
The nucleon spin structure at short distance
Seidl, Ralf
2008-10-01
The spin structure of the nucleon has been the basis of several surprises in the past. After the EMC experiment showed that the quark spin contribution to the nucleon spin was small, several experiments were performed to further investigate this ``spin crisis.'' Deep inelastic scattering (DIS) experiments at CERN, SLAC, and DESY successfully confirmed the low quark spin contribution to the nucleon. Using semi-inclusive DIS, SMC, HERMES and COMPASS were also able to obtain flavor separated quark polarizations. DIS experiments are only sensitive to gluon polarization at NLO via the QCD evolution of the structure function g1, or through di-jet/hadron production in photon-gluon fusion processes. Proton-proton collisions are sensitive to the gluon polarization at leading order. The RHIC experiments PHENIX and STAR have measured inclusive pion and jet asymmetries which exclude huge gluon polarizations but a substantial contribution to the spin of the nucleon is still possible. Another aspect of spin measurements are transverse spin phenomena. Once deemed to be vanishing in perturbative QCD recent nonzero transverse single spin asymmetries observed at RHIC and HERMES could be explained in the framework of transverse momentum dependent (TMD) distribution and fragmentation functions. One is the so-called Sivers function which requires a nonzero parton orbital angular momentum. Early global analysises were able to combine the data obtained at RHIC, COMPASS and HERMES. Another TMD function is the Collins fragmentation function, first measured at BELLE, which serves as a transverse spin analyzer to extract the quark transverse spin distribution from the SIDIS experiments. Also here a first global analysis of SIDIS and BELLE data has been successfully performed. An overview on recent spin related measurements at short distance, performed at PHENIX, STAR, BRAHMS, HERMES, COMPASS and Belle will be given.
Interference Fragmentation Functions and the Nucleon's Transversity
Jaffe, R. L.; Jin, Xuemin; Tang, Jian
1997-01-01
We introduce twist-two quark interference fragmentation functions in helicity density matrix formalism and study their physical implications. We show how the nucleon's transversity distribution can be probed through the final state interaction between two mesons ($\\pi^+\\pi^-$, $K\\bar K$, or $\\pi K$) produced in the current fragmentation region in deep inelastic scattering on a transversely polarized nucleon.
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
Nucleon structure functions from. nu. sub. mu. -Fe scattering at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Smith, W.H.; Sandler, P.H. (Wisconsin Univ., Madison (USA)); Merritt, F.S.; Oreglia, M.J.; Schumm, B.A. (Chicago Univ., IL (USA)); Arroyo, C.; Bachmann, K.T.; Blair, R.E.; Foudas, C.; King, B.J.; Lefmann, W.C.; Leung, W.C.; Mishra, S.R.; Oltman, E.; Quintas, P.Z.; Rabinowitz, S.A.; Sciulli, F.J.; Seligman, W.G.; Shaevitz, M.H. (Columbia Univ., New York (USA)); Bernstein, R.H.; Borcherding, F.O.; Fisk, H.E.; Lamm, M.J.; Marsh, W.; Merritt, K.W.; Schellman, H.; Yovanovitch, D. (Fermi National Accelerator Lab., Batavia, IL (USA)); Bodek, A.; Budd, H.S.; De Barbaro, P.; Sakumoto, W.K. (Rochester Univ., NY (USA))
1991-04-01
Preliminary measurements of structure functions have been made from a sample of 1,281,000 {nu}{sub {mu}} and 270,000 anti {nu}{sub {mu}} charged current events with 30 GeV < E{sub {nu}} < 600 GeV. These include a new value of the Gross-Llewellyn Smith Sum Rule, {integral} (1/x)(xF{sub 3})dx = 2.66 {+-} .03 (stat) {+-} .08 (syst), the ratio of cross sections, {sigma}(anti {nu}{sub {mu}})/{sigma}({nu}{sub {mu}}) = .511 {+-} .002 (stat) {+-} .005 (syst), and an analysis of the Q{sup 2} evolution of xF{sub 3}. (orig.).
Nejad, S Mohammad Moosavi; Tehrani, S Atashbar; Mahdavi, Mahdi
2016-01-01
We present a detailed QCD analysis of nucleon structure functions $xF_3 (x, Q^2)$, based on Laplace transforms and Jacobi polynomials approach. The analysis corresponds to the next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) approximation of perturbative QCD. The Laplace transform technique, as an exact analytical solution, is used for the solution of nonsinglet DGLAP evolution equations at low- and large-$x$ values. The extracted results are used as input to obtain the $x$ and Q$^2$ evolution of $xF_3(x, Q^2)$ structure functions using the Jacobi polynomials approach. In our work, the values of the typical QCD scale $\\Lambda_{\\overline{\\rm MS}}^{(n_f)}$ and the strong coupling constant $\\alpha_s(M_Z^2)$ are determined for four quark flavors ($n_f=4$) as well. A careful estimation of the uncertainties shall be performed using the Hessian method for the valence-quark distributions, originating from the experimental errors. We compare our valence-quark PDFs sets with those of other collabora...
Experimental results on polarized structure functions in deep inelastic lepton-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Stuart, L.
1994-08-01
A summary is given of experimental results on spin structure functions of the proton g{sub 1}{sup p}(x,Q{sup 2}), deuteron g{sub 1}{sup d}(x,Q{sup 2}), and neutron g{sub 1}{sup n}(x,Q{sup 2}) 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 Q{sup 2} 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.
Chiral nucleon-nucleon forces in nuclear structure calculations
Directory of Open Access Journals (Sweden)
Coraggio L.
2016-01-01
Full Text Available Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
Chiral nucleon-nucleon forces in nuclear structure calculations
Coraggio, L; Holt, J W; Itaco, N; Machleidt, R; Marcucci, L E; Sammarruca, F
2016-01-01
Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
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 Λ between 300 and 700 MeV
Quark distributions in nuclei and nuclear effects on nucleon structure functions
Institute of Scientific and Technical Information of China (English)
WANG Yan-Zhao; ZHANG Hong-Fei; GAO Yong-Hua; HOU Zhao-Yu; DONG Jian-Min; DUAN Chun-Gui; ZUO Wei
2009-01-01
Extended quark distribution functions are presented obtained by fitting a large amount of experi-mental data of the ι-A DIS process on the basis of an improved nuclear density model. The experimental data of ι-A DIS processes with A≥ 3 in the region 0.0010 ≤ x ≤ 0.9500 are quite satisfactorily described by using the extended formulae. Our knowledge of the influence of nuclear matter on the quark distributions is deepened.
International Nuclear Information System (INIS)
The authors presented a nuclear density empirical formula of the nucleus, where authors have established the connection between the nuclear density and the mean binding energy in nucleus. By using the formula, authors can get the nuclear density for various nuclei with A≥12. By means of the nuclear density model, authors calculate the nuclear effect function RA1/A2 (x, Q2). The calculated results are in good agreement with EMC experimental data
On the resonance structure in nucleon-nucleon scattering
Kloet, W. M.; Tjon, J. A.
1981-10-01
A possible explanation of resonance-like structure in 1D 2 and 3F 3 proton-proton phase parameters at medium energy is suggested by the analysis of an exactly soluble coupled channel model. Looping in the Argand plot is mainly due to the nucleon-delta branch cut. This effect is already present in the NΔ box diagram, but is modified by higher order multiple scattering. Poles occur close to the NΔ branch point and originate from left-hand singularities in the unphysical sheet.
Study of hadron structure in a deep-inelastic scattering of polarized leptons on polarized nucleons
International Nuclear Information System (INIS)
The problem is discussed of nucleon structure research in deep inelastic scattering processes of polarized leptons on polarized nucleons. Using a modified Kuti-Weisskopf model theoretical relations are derived for structure functions involved in the deep inelastic differential cross section of leptons on nucleons. (Z.J.)
Nucleon Resonances and Quark Structure
Londergan, J T
2009-01-01
A pedagogical review of the past 50 years of study of resonances, leading to our understanding of the quark content of baryons and mesons. The level of this review is intended for undergraduates or first-year graduate students. Topics covered include: the quark structure of the proton as revealed through deep inelastic scattering; structure functions and what they reveal about proton structure; and prospects for further studies with new and upgraded facilities, particularly a proposed electron-ion collider.
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 incorporates the terms des...
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.
Gravitational form factors and nucleon spin structure
Teryaev, O. V.
2016-10-01
Nucleon scattering by the classical gravitational field is described by the gravitational (energy-momentum tensor) form factors (GFFs), which also control the partition of nucleon spin between the total angular momenta of quarks and gluons. The equivalence principle (EP) for spin dynamics results in the identically zero anomalous gravitomagnetic moment, which is the straightforward analog of its electromagnetic counterpart. The extended EP (ExEP) describes its (approximate) validity separately for quarks and gluons and, in turn, results in equal partition of the momentum and total angular momentum. It is violated in quantum electrodynamics and perturbative quantum chromodynamics (QCD), but may be restored in nonperturbative QCD because of confinement and spontaneous chiral symmetry breaking, which is supported by models and lattice QCD calculations. It may, in principle, be checked by extracting the generalized parton distributions from hard exclusive processes. The EP for spin-1 hadrons is also manifested in inclusive processes (deep inelastic scattering and the Drell-Yan process) in sum rules for tensor structure functions and parton distributions. The ExEP may originate in either gravity-proof confinement or in the closeness of the GFF to its asymptotic values in relation to the mediocrity principle. The GFFs in time-like regions reveal some similarity between inflation and annihilation.
The spin structure of the nucleon
International Nuclear Information System (INIS)
This document describes the recent experimental results on the spin structure of the nucleon obtained with the electron accelerator Thomas Jefferson National Facility (Jefferson Lab), Virginia. We first discuss the goal of studying the nucleon spin structure and give the basis and phenomenology of high energy lepton scattering. Then, we discuss with some details a few sum rules concerning the spin structure of the nucleon. Those are important tools for studying the nucleon spin structure at Jefferson Lab. We then describe the present experimental situation and analyze the results. We have been able to determine an effective coupling constant for the strong interaction for any regime of quantum chromodynamics which proves that QCD is an approximately conformal theory. We conclude on the perspectives for this field of research, in particular with the 12 GeV energy upgrade of Jefferson Lab. The top priority will be the measurement of generalised parton distributions. The only issue that will stay misunderstood is the role of the very low x domain on the spin structure of the nucleon
Meson-cloud effects in the electromagnetic nucleon structure
Kupelwieser, Daniel
2013-01-01
We study how the electromagnetic structure of the nucleon is influenced by a pion cloud. To this aim we make use of a constituent-quark model with instantaneous confinement and a pion that couples directly to the quarks. To derive the invariant 1- photon-exchange electron-nucleon scattering amplitude we employ a Poincar\\'e- invariant coupled-channel formulation which is based on the point-form of relativistic quantum mechanics. We argue that the electromagnetic nucleon current extracted from this amplitude can be reexpressed in terms of pure hadronic degrees of freedom with the quark substructure of the pion and the nucleon being encoded in electromagnetic and strong vertex form factors. These are form factors of bare particles, i.e. eigenstates of the pure confinement problem. First numerical results for (bare) photon-nucleon and pion-nucleon form factors, which are the basic ingredients of the further calculation, are given for a simple 3-quark wave function of the nucleon.
Nucleon spin structure at low momentum transfers
Pasechnik, Roman; Teryaev, Oleg
2010-01-01
The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into account higher order radiative and higher twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent proton structure function $\\Gamma_1^{p}(Q^2)$ and on the Bjorken sum rule $\\Gamma_1^{p-n}(Q^2)$. By using the singularity-free analytic perturbation theory we demonstrate that the matching point between chiral-like positive-$Q^2$ expansion and QCD operator product $1/Q^2$-expansion for the nucleon spin sum rules can be shifted down to rather low $Q\\simeq\\Lambda_{QCD}$ leading to a good description of recent proton, neutron, deuteron and Bjorken sum rule data at all accessible $Q^2$.
Nucleon spin structure at low momentum transfers
Pasechnik, Roman S.; Soffer, Jacques; Teryaev, Oleg V.
2010-10-01
The generalized Gerasimov-Drell-Hearn sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the Q2 dependence of the Gerasimov-Drell-Hearn sum rule. We take into account higher order radiative and higher-twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent proton structure function Γ1p(Q2) and on the Bjorken sum rule Γ1p-n(Q2). By using the singularity-free analytic perturbation theory we demonstrate that the matching point between chiral-like positive-Q2 expansion and QCD operator product 1/Q2 expansion for the nucleon spin sum rules can be shifted down to rather low Q≃ΛQCD leading to a good description of recent proton, neutron, deuteron, and Bjorken sum rule data at all accessible Q2.
New insights into the spin structure of the nucleon
Bernard, V; Krebs, H; Meißner, U -G
2012-01-01
We analyze the low-energy spin structure of the nucleon in a covariant effective field theory with explicit spin-3/2 degrees of freedom to third order in the small scale expansion. Using the available data on the strong and electromagnetic width of the Delta-resonance, we give parameter-free predictions for various spin-polarizabilities and moments of spin structure functions. We find an improved description of the nucleon spin structure at finite photon virtualities for some observables and point out the necessity of a fourth order calculation.
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.
Energy Technology Data Exchange (ETDEWEB)
Bartels, Jochen [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Golec-Biernat, Krzysztof [Rzeszow Univ. (Poland). Inst. of Physics; Polish Academy of Sciences, Krakow (Poland). Inst. of Nuclear Physics; Motkyka, Leszek [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Uniwersytet Jagiellonski, Krakow (Poland). Inst. Fizyki
2009-11-15
Higher twist effects in the deeply inelastic scattering are studied. We start with a short review of the theoretical results on higher twists in QCD. Within the saturation model we perform a twist analysis of the nucleon structure functions F{sub T} and F{sub L} at small value of the Bjorken variable x. The parameters of the model are fitted to the HERA F{sub 2} data, and we derive a prediction for the longitudinal structure function F{sub L}. We conclude that for F{sub L} the higher twist corrections are sizable whereas for F{sub 2}=F{sub T}+F{sub L} there is a nearly complete cancellation of twist-4 corrections in F{sub T} and F{sub L}. We discuss a few consequences for future LHC measurements. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Yongguang Liang; Michael Christy; Abdellah Ahmidouch; Christopher Armstrong; John Arrington; Arshak Asaturyan; Steven Avery; O. Baker; Douglas Beck; Henk Blok; C.W. Bochna; Werner Boeglin; Peter Bosted; Maurice Bouwhuis; Herbert Breuer; Daniel Brown; Antje Bruell; Roger Carlini; Jinseok Cha; Nicholas Chant; Anthony Cochran; Leon Cole; Samuel Danagoulian; Donal Day; James Dunne; Dipangkar Dutta; Rolf Ent; Howard Fenker; B. Fox; Liping Gan; Haiyan Gao; Kenneth Garrow; David Gaskell; Ashot Gasparian; Don Geesaman; Ronald Gilman; Paul Gueye; Mark Harvey; Roy Holt; Xiaodong Jiang; Mark Jones; Cynthia Keppel; Edward Kinney; Wolfgang Lorenzon; Allison Lung; David Mack; Pete Markowitz; J.W. Martin; Kevin McIlhany; Daniella Mckee; David Meekins; M.A. Miller; Richard Milner; Joseph Mitchell; Hamlet Mkrtchyan; Robert Mueller; Alan Nathan; Gabriel Niculescu; Maria-Ioana Niculescu; Thomas O' neill; Vassilios Papavassiliou; Stephen Pate; Rodney Piercey; David Potterveld; Ronald Ransome; Joerg Reinhold; E. Rollinde; Oscar Rondon-Aramayo; Philip Roos; Adam Sarty; Reyad Sawafta; Elaine Schulte; Edwin Segbefia; C. Smith; Samuel Stepanyan; Steffen Strauch; Vardan Tadevosyan; Liguang Tang; Raphael Tieulent; Vladas Tvaskis; Alicia Uzzle; William Vulcan; Stephen Wood; Feng Xiong; Lulin Yuan; Markus Zeier; Benedikt Zihlmann; Vitaliy Ziskin
2004-10-01
We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q{sup 2} < 5.5 GeV{sup 2}. The data have been used to accurately perform over 170 Rosenbluth-type longitudinal/transverse separations. The precision R = {sigma}{sub L}/{sigma}{sub T} data are presented here, along with the first separate values of the inelastic structure functions F{sub 1} and F{sub L} in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q{sup 2} = 1 GeV{sup 2} in the separated structure functions independently.
Spin Structure of the Nucleon - Proceedings of the Riken Symposium
Shibata, S.; Ohta, N.; Saito, T.-A.
1996-08-01
The Table of Contents for the full book PDF is as follows: * Organizing Committee * Foreword * Theoretical Overview * The Context of High Energy QCD Spin Physics * Experimental Studies I * PHENIX and Spin Physics * RHIC Spin Project - Acceleration of Polarized Protons * CIAE Activities for the PHENIX Experiment * Spin Physics with PHENIX Detector System at RHIC * Experiments on Spin-dependent Structure Functions of the Nucleon * Measurements of the Spin-dependent Structure Function of the Nucleon at the Spin Muon Collaboration * Theoretical Studies * Higher-twist Effects in Spin Structure Functions * Light Hadrons from Lattice QCD in a (2.4 fm)3 Box at 4-GeV Cutoff * Tensor Charge of the Nucleon on the Lattice * Perturbative QCD Study on the Chiral-Odd Twist-3 Structure Function: hL(x,Q2) * Strange Matrix Elements of the Proton and Instantons in QCD * Experimental Studies II * Proton Structure Functions from ZEUS * Measurements of the Photon Structure Functions F_{2}^γ * Constraint on the Proton Structure from CDF: Lepton Charge Asymmetry in W Decays * A Search for Jet Handedness in Hadronic Z0 Decays * Concluding Remarks * High Energy Spin Physics - Past, Present and Future * Program
Nucleon Structure and Generalized Parton Distributions
Energy Technology Data Exchange (ETDEWEB)
Eric Voutier
2006-06-28
This paper discusses a selected part of the experimental program dedicated to the study of Generalized Parton Distributions, a recently introduced concept which provides a comprehensive framework for investigations of the partonic structure of the nucleon. Particular emphasis is put on the Deeply Virtual Compton Scattering program performed at the Jefferson Laboratory. The short and long term future of this program is also discussed in the context of the several experimental efforts aiming at a complete and exhaustive mapping of Generalized Parton Distributions.
Structure and spin of the nucleon
International Nuclear Information System (INIS)
Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions (TDM) and Generalized Parton Distributions (GPD), were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements. (author)
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.
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.
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
Electromagnetic studies of nucleon and nuclear structure
Energy Technology Data Exchange (ETDEWEB)
Heisenberg, J.H.; Calarco, J.R.; Hersman, F.W.; Dawson, J.F.
1993-06-01
Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on {sup 12}C and {sup 16}O are reported, as well as work on nuclear structure models and instrumentation development.
International Nuclear Information System (INIS)
Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)
Nucleon structure from 2+1-flavor dynamical DWF ensembles
Abramczyk, Michael; Lytle, Andrew; Ohta, Shigemi
2016-01-01
Nucleon isovector vector- and axialvector-current form factors, the renormalized isovector transversity and scalar charge, and the bare quark momentum and helicity moments of isovector structure functions are reported with improved statistics from two recent RBC+UKQCD 2+1-flavor dynamical domain-wall fermions ensembles: Iwasaki\\(\\times\\)DSDR gauge \\(32^3\\times64\\) at inverse lattice spacing of 1.38 GeV and pion mass of 249 and 172 MeV.
Panofsky Prize talk: The Structure of the Nucleon
Bodek, Arie
2004-05-01
Information about the quark distribution functions in nucleons and nuclei has been obtained from a range of experiments in various laboratories including electron-nucleon/nucleus, neutrino-nucleon/nucleus, and production of W and Z Bosons in proton-antiproton collisions. I review the the different experimental and theoretical tools that were developed to extract parton distribution functions from these experiments with very different probes.
Nucleon wave function from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Warkentin, Nikolaus
2008-04-15
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
Nucleon wave function from lattice QCD
International Nuclear Information System (INIS)
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
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
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.
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.
Boson-exchange nucleon-nucleon potential and nuclear structure
International Nuclear Information System (INIS)
A fully momentum-dependent one-boson-exchange potential is derived which takes into account the mesons, π, eta, sigma, rho, ω and phi. Scattering bound states and nuclear matter properties are studied in momentum space. The use of such potential is shown to be as easy as the use of more simple phenomenological interactions. In nuclear matter the formalism of Bethe-Goldstone is chosen to compute the binding energy versus density in the approximation of two-body and three-body correlations. The three-body correlated wave function obtained is then used
Probing nucleon structure on the lattice
International Nuclear Information System (INIS)
The QCDSF/UKQCD Collaboration has an ongoing program to calculate nucleon matrix elements with two flavours of dynamical O(a) improved Wilson fermions. Here we present recent results on the electromagnetic form factors, the quark momentum fraction left angle x right angle and the first three moments of the nucleon's spin-averaged and spin-dependent generalised parton distributions, including preliminary results with pion masses as low as 320 MeV. (orig.)
Nucleon Structure and Hyperon Form Factors from Lattice QCD
International Nuclear Information System (INIS)
In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point. to be 1.23(5), consistent with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(2G), consistent with the Adelaide-JLab Collaboration's result. The hyperon Σ and Ξ axial coupling constants are also performed for the first time in a lattice calculation, gσσ = 0.441(14) and gΞΞ -0.277(11)
Nucleon Structure and hyperon form factors from lattice QCD
International Nuclear Information System (INIS)
In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point to be 1.23(5), consistent with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(26), consistent with the Adelaide-JLab Collaboration's result. The hyperon Sigma and Xi axial coupling constants are also performed for the first time in a lattice calculation, g#Sigma##Sigma# = 0.441(14) and g#Xi##Xi# = -0.277(11)
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 ρ ∼ 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.
The Spin Structure of the nucleon
Deur, Alexandre
2015-10-01
This talk will review the status of the experiments studying the spin structure of the nucleon. After a brief overview of the topics, I will focus on the program measuring the generalized Gerasimov-Drell-Hearn (GDH) sum, in the context of connecting the effective descriptions of the strong force at long distances to its fundamental partonic description at short distances. The generalized GDH sum rule is a theoretical relation valid at any distance. Consequently, it can be an Ariadne's thread to follow to understand how the transition between the partonic to hadronic descriptions happens. Measurements at intermediate and short distances have been made available in the 1990s and 2000s. Long distance results are being now finalized. With them, a large part of this experimental program will be completed. I will give the status of the measurements at long distances. I will then conclude the talk with a practical example on how the GDH data are used to connect the fundamental and effective descriptions of the strong force. Such example demonstrates how the generalized GDH program is bearing fruits.
Relativistic spectral function of nucleon in hot nuclear matter
Ghosh, Sabyasachi; Mallik, S.; Sarkar, Sourav
2010-01-01
We present a simple calculation of the nucleon self-energy in nuclear matter at finite temperature in a relativistic framework, using the real time thermal field theory. The imaginary parts of one-loop graphs are identified with discontinuities across the unitary and the Landau cuts. We find that in general both the cuts contribute significantly to the spectral function in the region of (virtual) nucleon mass usually considered, even though the unitary cut is ignored in the literature. Also o...
Lattice QCD Calculation of Nucleon Structure
Energy Technology Data Exchange (ETDEWEB)
Liu, Keh-Fei [University of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy; Draper, Terrence [University of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy
2016-08-30
It is emphasized in the 2015 NSAC Long Range Plan [1] that "understanding the structure of hadrons in terms of QCD's quarks and gluons is one of the central goals of modern nuclear physics." Over the last three decades, lattice QCD has developed into a powerful tool for ab initio calculations of strong-interaction physics. Up until now, it is the only theoretical approach to solving QCD with controlled statistical and systematic errors. Since 1985, we have proposed and carried out first-principles calculations of nucleon structure and hadron spectroscopy using lattice QCD which entails both algorithmic development and large scale computer simulation. We started out by calculating the nucleon form factors ₋ electromagnetic [2], axial-vector [3], π NN [4], and scalar [5] form factors, the quark spin contribution [6] to the proton spin, the strangeness magnetic moment [7], the quark orbital angular momentum [8], the quark momentum fraction [9], and the quark and glue decomposition of the proton momentum and angular momentum [10]. These first round of calculations were done with Wilson fermions in the `quenched' approximation where the dynamical effects of the quarks in the sea are not taken into account in the Monte Carlo simulation to generate the background gauge configurations. Beginning in 2000, we have started implementing the overlap fermion formulation into the spectroscopy and structure calculations [11, 12]. This is mainly because the overlap fermion honors chiral symmetry as in the continuum. It is going to be more and more important to take the symmetry into account as the simulations move closer to the physical point where the u and d quark masses are as light as a few MeV only. We began with lattices which have quark masses in the sea corresponding to a pion mass at ~ 300 MeV and obtained the strange form factors [13], charm and strange quark masses, the charmonium spectrum and the D_{s} meson decay constant fD_{s} [14], the
Lattice QCD Calculation of Nucleon Structure
Energy Technology Data Exchange (ETDEWEB)
Liu, Keh-Fei; Draper, Terrence
2016-08-30
It is emphasized in the 2015 NSAC Long Range Plan [1] that \\understanding the structure of hadrons in terms of QCD's quarks and gluons is one of the central goals of modern nuclear physics." Over the last three decades, lattice QCD has developed into a powerful tool for ab initio calculations of strong-interaction physics. Up until now, it is the only theoretical approach to solving QCD with controlled statistical and systematic errors. Since 1985, we have proposed and carried out rst-principles calculations of nucleon structure and hadron spectroscopy using lattice QCD which entails both algorithmic development and large scale computer simulation. We started out by calculating the nucleon form factors { electromagnetic [2], axial-vector [3], NN [4], and scalar [5] form factors, the quark spin contribution [6] to the proton spin, the strangeness magnetic moment [7], the quark orbital angular momentum [8], the quark momentum fraction [9], and the quark and glue decomposition of the proton momentum and angular momentum [10]. These rst round of calculations were done with Wilson fermions in the `quenched' approximation where the dynamical e ects of the quarks in the sea are not taken into account in the Monte Carlo simulation to generate the background gauge con gurations. Beginning in 2000, we have started implementing the overlap fermion formulation into the spectroscopy and structure calculations [11, 12]. This is mainly because the overlap fermion honors chiral symmetry as in the continuum. It is going to be more and more important to take the symmetry into account as the simulations move closer to the physical point where the u and d quark masses are as light as a few MeV only. We began with lattices which have quark masses in the sea corresponding to a pion mass at 300 MeV and obtained the strange form factors [13], charm and strange quark masses, the charmonium spectrum and the Ds meson decay constant fDs [14], the strangeness and charmness [15], the
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.
Experimental study of the nucleon spin structure
International Nuclear Information System (INIS)
After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.)
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.).
Di-nucleon structures in homogeneous nuclear matter based on two- and three-nucleon interactions
Arellano, H F; Rios, Arnau
2016-01-01
We investigate homogeneous nuclear matter within the Brueckner-Hartree-Fock (BHF) approach in the limits of isospin-symmetric nuclear matter (SNM) as well as pure neutron matter at zero temperature. The study is based on realistic representations of the internucleon interaction as given by Argonne v18, Paris, Nijmegen I and II potentials, in addition to chiral N$^{3}$LO interactions, including three-nucleon forces up to N$^{2}$LO. Particular attention is paid to the presence of di-nucleon bound states structures in $^1\\textrm{S}_0$ and $^3\\textrm{SD}_1$ channels, whose explicit account becomes crucial for the stability of self-consistent solutions at low densities. A characterization of these solutions and associated bound states is discussed. We confirm that coexisting BHF single-particle solutions in SNM, at Fermi momenta in the range $0.13-0.3$~fm$^{-1}$, is a robust feature under the choice of realistic internucleon potentials.
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
Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.
Delineating the polarized and unpolarized partonic structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Jimenez-Delgado, Pedro [JLAB
2015-03-01
Our latest results on the extraction of parton distribution functions of the nucleon are reported. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are given, including a careful treatment of hadronic and nuclear corrections, as well as results on the impact of present and future data in our understanding of the spin of the nucleon.
Interacting boson models of nuclear and nucleon structure
Bijker, R
1998-01-01
Interacting boson models provide an elegant and powerful method to describe collective excitations of complex systems by introducing a set of effective degrees of freedom. We review the interacting boson model of nuclear structure and discuss a recent extension to the nucleon and its excited states.
Spin Structure of the Nucleon on the Light Front
International Nuclear Information System (INIS)
We briefly review the spin structure of the nucleon and show that it is best thought in the light-front formulation. We discuss in particular the longitudinal and transverse spin sum rules, the proper definition of canonical orbital angular momentum and the spin–orbit correlation. (author)
Lepton-quark scattering and nucleon spin structure
Hochberg, David
Consideration is given to the asymmetries arising from the deep inelastic scattering of longitudinally polarized electrons and positrons with longitudinally polarized protons at ep collider energies. Information from such measurements will provide means for testing models of nucleon spin structure. The Carlitz-Kaur model of spin structure is used as a guide for estimating the behavior of these asymmetries, which arise from the interference of the electromagnetic and neutral currents.
Numerical Toy-Model Calculation of the Nucleon Spin Autocorrelation Function in a Supernova Core
Raffelt, G G; Raffelt, Georg; Sigl, Guenter
1999-01-01
We develop a simple model for the evolution of a nucleon spin in a hot and dense nuclear medium. A given nucleon is limited to one-dimensional motion in a distribution of external, spin-dependent scattering potentials. We calculate the nucleon spin autocorrelation function numerically for a variety of potential densities and distributions which are meant to bracket realistic conditions in a supernova core. For all plausible configurations the width of the spin-density structure function is found to be less than the temperature. This is in contrast with a naive perturbative calculation based on the one-pion exchange potential which overestimates the width and thus suggests a large suppression of the neutrino opacities by nucleon spin fluctuations. Our results suggest that it may be justified to neglect the collisional broadening of the spin-density structure function for the purpose of estimating the neutrino opacities in the deep inner core of a supernova. On the other hand, we find no indication that process...
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)
In the Cloudy Bag Model hadrons are treated as quarks confined in an M.I.T. bag that is surrounded by a cloud of pions. Computations of the charge and magnetism distributions of nucleons and baryons, pion-nucleon scattering, and the strong and electromagnetic decays of mesons are discussed. Agreement with experimental results is excellent if the nucleon bag radius is in the range between 0.8 and 1.1 fm. Underlying qualitative reasons which cause the pionic corrections to be of the obtained sizes are analyzed. If bags are of such reasonably large sizes, nucleon bags in nuclei will often come into contact. As a result one needs to consider whether explicit quark degrees of freedom are relevant for Nuclear Physics. To study such possibilities a model which treats a nucleus as a collection of baryons, pions and six-quark bags is discussed. In particular, the short distance part of a nucleon-nucleon wave function is treated as six quarks confined in a bag. This approach is used to study the proton-proton weak interaction, the asymptotic D to S state ratio of the deuteron, the pp → dπ reaction, the charge density of /sup 3/He, magnetic moments of /sup 3/He and /sup 3/H and, the /sup 3/He-/sup 3/H binding energy difference. It is found that quark effects are very relevant for understanding nuclear properties
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...
Statistical effect in the parton distribution functions of the nucleon
Zhang, Yunhua; Ma, Bo-Qiang
2008-01-01
A new and simple statistical approach is performed to calculate the parton distribution functions (PDFs) of the nucleon in terms of light-front kinematic variables. We do not put in any extra arbitrary parameter or corrected term by hand, which guarantees the stringency of our approach. Analytic expressions of the $x$-dependent PDFs are obtained in the whole $x$ region [0,1], and some features, especially the low-$x$ rise, are more agreeable with experimental data than those in some previous instant-form statistical models in the infinite-momentum frame (IMF). Discussions on heavy-flavored PDFs are also presented.
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 Λ, at next to leading order: hydrogen target: Λsub(MS) = 139(+170-100)MeV; iron target: Λsub(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
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...
Maxwell, C J
2002-01-01
We use recently calculated next-next-to-leading order (NNLO) anomalous dimension coefficients for the n=1,3,5,...,13 moments of the xF3 structure function in nuN scattering, together with the corresponding three-loop Wilson coefficients, to obtain improved QCD predictions for the moments. The Complete Renormalization Group Improvement (CORGI) approach is used, in which all dependence on renormalization or factorization scales is avoided by a complete resummation of ultraviolet logarithms. The Bernstein Polynomial method is used to compare these QCD predictions to the xF3 data of the CCFR collaboration. Direct fits for LambdaMSbar(5), with Nf=5 effective quark flavours, over the range 20
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
Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction
Aznauryan, I G; Braun, V; Brodsky, S J; Burkert, V D; Chang, L; Chen, Ch; El-Bennich, B; Cloët, I C; Cole, P L; Edwards, R G; Fedotov, G V; Giannini, M M; Gothe, R W; Lin, Huey-Wen; Kroll, P; Lee, T -S H; Melnitchouk, W; Mokeev, V I; Peña, M T; Ramalho, G; Roberts, C D; Santopinto, E; de Teramond, G F; Tsushima, K; Wilson, D J
2013-01-01
Studies of the structure of excited baryons are key to the N* program at Jefferson Lab. Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever yet achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electroproduction off pro...
Tagged nuclear structure functions with $HERMES$
Silvano SimulaINFN - Sezione Sanita'
2014-01-01
The production of slow nucleons in semi-inclusive deep inelastic electron scattering off nuclei, $A(e, e'N)X$, is analyzed for kinematical conditions accessible at $HERA$ with the $HERMES$ detector. The sensitivity of the semi-inclusive cross section to possible medium-dependent modifications of the nucleon structure function is illustrated.
Nucleon Resonance Structure Studies via Exclusive KY Electroproduction
Carman, Daniel S.
2016-06-01
Studying the structure of excited nucleon states employing the electroproduction of exclusive reactions is an important avenue for exploring the nature of the non-perturbative strong interaction. The electrocouplings of N^* states in the mass range below 1.8 GeV have been determined from analyses of CLAS π N , η N , and π π N data. This work has made it clear that consistent results from independent analyses of several exclusive channels with different couplings and non-resonant backgrounds but the same N^* electro-excitation amplitudes, is essential to have confidence in the extracted results. In terms of hadronic coupling, many high-lying N^* states preferentially decay through the π π N channel instead of π N . Data from the KY channels will therefore be critical to provide an independent analysis to compare the extracted electrocouplings for the high-lying N^* states against those determined from the π N and π π {N} channels. A program to study excited N^* state structure in both non-strange and strange exclusive electroproduction channels using CLAS12 will measure differential cross sections and polarization observables to be used as input to extract the γ _v{{NN}}^* electrocoupling amplitudes for the most prominent N^* states in the range of invariant energy W up 3 GeV in the virtually unexplored domain of momentum transfers Q^2 up to 12 GeV^2.
Studies of the 3D Structure of the Nucleon at Jlab
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-07-01
Studies of the 3D structure of the nucleon encoded in Transverse Momentum Dependent distribution and fragmentation functions of partons and Generalized Parton Distributions are among the key objectives of the JLab 12 GeV upgrade and the Electron Ion Collider. Main challenges in extracting 3D partonic distributions from precision measurements of hard scattering processes include clear understanding of leading twist QCD fundamentals, higher twist effects, and also correlations of hadron production in target and current fragmentation regions. In this contribution we discuss some ongoing studies and future measurements of spin-orbit correlations at Jefferson Lab.
Studies of the 3D Structure of the Nucleon at JLab
Avakian, Harut
2016-08-01
Studies of the 3D structure of the nucleon encoded in transverse momentum dependent distribution and fragmentation functions of partons and generalized parton distributions are among the key objectives of the JLab 12 GeV upgrade and the electron ion collider. Main challenges in extracting 3D partonic distributions from precision measurements of hard scattering processes include clear understanding of leading twist QCD fundamentals, higher twist effects, and also correlations of hadron production in target and current fragmentation regions. In this contribution we discuss some ongoing studies and future measurements of spin-orbit correlations at Jefferson Lab.
Nucleon Resonance Structure Studies Via Exclusive KY Electroproduction
Carman, Daniel S
2016-01-01
Studying the structure of excited nucleon states employing the electroproduction of exclusive reactions is an important avenue for exploring the nature of the non-perturbative strong interaction. The electrocouplings of $N^*$ states in the mass range below 1.8~GeV have been determined from analyses of CLAS $\\pi N$, $\\eta N$, and $\\pi \\pi N$ data. This work has made it clear that consistent results from independent analyses of several exclusive channels with different couplings and non-resonant backgrounds but the same $N^*$ electro-excitation amplitudes, is essential to have confidence in the extracted results. In terms of hadronic coupling, many high-lying $N^*$ states preferentially decay through the $\\pi \\pi N$ channel instead of $\\pi N$. Data from the $KY$ channels will therefore be critical to provide an independent analysis to compare the extracted electrocouplings for the high-lying $N^*$ states against those determined from the $\\pi N$ and $\\pi \\pi N$ channels. A program to study excited $N^*$ state s...
Calculation of moments of structure functions
International Nuclear Information System (INIS)
The progress on the lattice computation of low moments of both the unpolarised and polarised nucleon structure functions is reviewed with particular emphasis on continuum and chiral extrapolations and comparison between quenched and unquenched fermions. (orig.)
Structure functions near the chiral limit
International Nuclear Information System (INIS)
We compute hadron masses and the lowest moments of unpolarized and polarized nucleon structure functions down to pion masses of 300 MeV, in an effort to make unambiguous predictions at the physical light quark mass. (orig.)
Structure and Flow of the Nucleon Eigenstates in Lattice QCD
Mahbub, M. Selim; Kamleh, Waseem; Leinweber, Derek B.; Moran, Peter J.; Williams, Anthony G.
2013-01-01
A determination of the excited energy eigenstates of the nucleon, $s=c{1}{2}$, $I={1}{2}$, $N^{\\pm}$, is presented in full QCD using 2+1 flavor PACS-CS gauge configurations. The correlation-matrix method is used and is built using standard nucleon interpolators employing smearings at the fermion sources and sinks. We develop and demonstrate a new technique that allows the eigenvectors obtained to be utilized to track the propagation of the intrinsic nature of energy-states from one quark mass...
Multi-Nucleon Short-Range Correlation Model for Nuclear Spectral Functions: I. Theoretical Framework
Artiles, Oswaldo
2016-01-01
We develop a theoretical approach for nuclear spectral functions at high missing momenta and removal energy based on the multi-nucleon short-range correlation~(SRC) model. The approach is based on the effective Feynman diagrammatic method which allows to account for the relativistic effects important in the SRC domain. In addition to two-nucleon SRC with center of mass motion we derived also the contribution of three-nucleon SRCs to the nuclear spectral functions. The latter is modeled based on the assumption that 3N SRCs are a product of two sequential short range NN interactions. This approach allowed us to express the 3N SRC part of the nuclear spectral function as a convolution of two NN SRCs. Thus the knowledge of 2N SRCs allows us to model both two- and three-nucleon SRC contribution to the spectral function. The derivations of the spectral functions are based on the two theoretical frameworks in evaluating covariant Feynman diagrams: In the first, referred as virtual nucleon approximation, we reduce Fe...
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
The Jefferson Lab Contribution to the QCD Spin Structure of the Nucleon
Energy Technology Data Exchange (ETDEWEB)
Michel Garcon
2004-10-10
From inclusive to semi-inclusive and exclusive (polarized) deep inelastic scattering, the quark structure of the nucleon is being studied with increasingly precise experiments at Jefferson Lab. We will review here the ongoing programs to determine polarized parton distributions--helicity and transversity--as well as generalized parton distributions, addressing the question of intrinsic spin and orbital angular momentum of quarks in the nucleon.
Structure and Flow of the Nucleon Eigenstates in Lattice QCD
Mahbub, M Selim; Leinweber, Derek B; Moran, Peter J; Williams, Anthony G
2013-01-01
A determination of the excited energy eigenstates of the nucleon, $s=\\frac{1}{2}$, $I=\\frac{1}{2}$, $N^{\\pm}$, is presented in full QCD using 2+1 flavor PACS-CS gauge configurations. The correlation-matrix method is used and is built using standard nucleon interpolators employing smearings at the fermion sources and sinks. We develop and demonstrate a new technique that allows the eigenvectors obtained to be utilized to track the propagation of the intrinsic nature of energy-states from one quark mass to the next. This approach is particularly useful for larger dimension correlation matrices where more near-degenerate energy-states can appear in the spectrum.
Near Forward pp Elastic Scattering at LHC and Nucleon Structure
Islam, M M; Prokudin, A V
2006-01-01
High energy proton-proton and antiproton-proton elastic scattering are studied first in a model where the nucleon has an outer cloud and an inner core. Elastic scattering is viewed as due to two processes: a) diffraction scattering originating from cloud-cloud interaction; b) a hard or large |t| scattering originating from one nucleon core scattering off the other via vector meson omega exchange, while their outer clouds interact independently. The omega-exchange amplitude shows that omega behaves like an elementary vector meson at high energy, contrary to a regge pole behavior. This behavior, however, can be understood in the nonlinear sigma-model where omega couples to a topological baryonic current like a gauge boson, and the nucleon is described as a topological soliton. Further investigation shows that the underlying effective field theory model is a gauged linear sigma-model that has not only the pion sector and the Wess-Zumino-Witten action of the nonlinear sigma-model, but also a quark-scalar sector. ...
Nucleon localization in light and heavy nuclei
Zhang, C L; Nazarewicz, W
2016-01-01
An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate $\\alpha$-cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the cluster structures in deformed light nuclei and study the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the deformed harmonic oscillator model. Realistic calculations are carried out using self-consistent nuclear density functional theory with quantified energy density functionals optimized for fission studies. We study particle densities and spatial nucleon localization distributions for deformed cluster configurations of $^{8}$Be and $^{20}$Ne, and also along...
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Energy Technology Data Exchange (ETDEWEB)
Mokeev, Viktor I. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Aznauryan, Inna G. [Skobeltsyn Nuclear Physics Institute and Physics Department at Moscow State University, Moscow, Russia; Burkert, Volker D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Gothe, Ralf W. [Univ. of South Carolina, Columbia, SC (United States)
2016-03-01
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and $N \\rightarrow N^*$ transition form factors. We will also discuss further convincing evidences for a new baryon state $N^{\\, '}(1720)3/2^+$ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Mokeev, Victor; Burkert, Volker; Gothe, Ralf
2015-01-01
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and $N \\rightarrow N^*$ transition form factors. We will also discuss further convincing evidences for a new baryon state $N^{\\, '}(1720)3/2^+$ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Mokeev, V. I.; Aznauryan, I. G.; Burkert, V. D.; Gothe, R. W.
2016-03-01
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the γυpN* transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and N → N* transition form factors. We will also discuss further convincing evidences for a new baryon state N' (1720)3/2+ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
Last Experimental Results Obtained at SLAC on the Nucleon Spin Structure
Rock, S E
2003-01-01
Recent precise measurements of the spin structure function g sub 1 for proton and for deuteron using deep inelastic scattering of polarized electrons from polarized ammonia targets are presented. The integrals GAMMA sub 1 integral sub 0 sup 1 g sub 1 (x)dx evaluated at the average experimental Q = 3(GeV/c) sup 2 are in agreement with previous results and well below the Ellis-Jaffe sumrule prediction, while the Bjoerken sumrule prediction on GAMMA sub 1 sup p - GAMMA sub 1 sup n is satisfied. The analysis of the results in term of Quark Parton Model implies that the quark carry about a third of the nucleon helicity.
Studies of the nucleon structure in back-to-back SIDIS
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-03-01
The Deep Inelastic Scattering (DIS) proved to be a great tool in testing of the theory of strong interactions, which was a major focus in last decades. Semi-Inclusive DIS (SIDIS), with detection of an additional hadron allowed first studies of 3D structure of the nucleon, moving the main focus from testing the QCD to understanding of strong interactions and quark gluon dynamics to address a number of puzzles accumulated in recent years. Detection of two hadrons in SIDIS, which is even more complicated, provides access to details of quark gluon interactions inaccessible in single-hadron SIDIS, providing a new avenue to study the complex nucleon structure. Large acceptance of the Electron Ion Collider, allowing detection of two hadrons, produced back-to-back in the current and target fragmentation regions, combined with clear separation of two regions, would provide a unique possibility to study the nucleon structure in target fragmentation region, and correlations of target and current fragmentation regions.
An overview of recent nucleon spin structure measurements at Jefferson Lab
Energy Technology Data Exchange (ETDEWEB)
Allada, Kalyan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-02-01
Jefferson Lab have made significant contributions to improve our knowledge of the longitudinal spin structure by measuring polarized structure functions, g1 and g2, down to Q2 = 0.02 GeV2. The low Q2 data is especially useful in testing the Chiral Perturbation theory (cPT) calculations. The spin-dependent sum rules and the spin polarizabilities, constructed from the moments of g1 and g2, provide an important tool to study the longitudinal spin structure. We will present an overview of the experimental program to measure these structure functions at Jefferson Lab, and present some recent results on the neutron polarizabilities, proton g1 at low Q2, and proton and neutron d2 measurement. In addition to this, we will discuss the transverse spin structure of the nucleon which can be accessed using chiral-odd transversity distribution (h1), and show some results from measurements done on polarized 3He target in Hall A.
Energy Technology Data Exchange (ETDEWEB)
Bratt, Jonathan; Engelhardt, Michael; Haegler, Philipp; Huey-Wen, Lin; Lin, Meifeng; Meyer, Harvey; Musch, Bernhard; Negele, John; Orginos, Konstantinos; Pochinsky, Andrew; Procura, Massimiliano; Richards, David; Schroers, Wolfram; Syritsyn, Sergey
2010-11-01
We present high statistics results for the structure of the nucleon from a mixed-action calculation using 2+1 flavors of asqtad sea and domain wall valence fermions. We perform extrapolations of our data based on different chiral effective field theory schemes and compare our results with available information from phenomenology. We discuss vector and axial form factors of the nucleon, moments of generalized parton distributions, including moments of forward parton distributions, and implications for the decomposition of the nucleon spin.
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.
The Structure of the Nucleon, Three Decades of Investigation (1967-2004)
Bodek, Arie
2005-02-01
A personal historical account of three decades of experiments that led to a detailed understanding of the structure of the nucleon and the theory of Quantum Chromodynamics. (Panofsky Prize 2004 Talk, Presented at NuInt04, Mar. 2004, Laboratori Nazionali del Gran Sasso - INFN - Assergi, Italy [ http://nuint04.lngs.infn.it/])
Polarized structure of nucleon in the valon representation
Arash, Firooz; Taghavi-Shahri, Fatemeh
2007-07-01
We have utilized the concept of valon model to calculate the spin structure functions of proton, neutron, and deuteron. The valon structure itself is universal and arises from the perturbative dressing of the valence quark in QCD. Our results agree rather well with all of the relevant experimental data on g1p,n,d and gA/gV, and suggests that the sea quark contribution to the spin of proton is consistent with zero. It also reveals that while the total quark contribution to the spin of a valon, ΔΣvalon, is almost constant at Q2 >= 1 the gluon contribution grows with the increase of Q2 and hence requiring a sizable negative orbital angular momentum component Lz. This component along with the singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD . We speculate that gluon contribution to the spin content of the proton is about 60% for all Q2 values. Finally, we show that the size of gluon polarization and hence, Lz, is sensitive to the initial scale Q02.
Polarized structure of nucleon in the valon representation
International Nuclear Information System (INIS)
We have utilized the concept of valon model to calculate the spin structure functions of proton, neutron, and deuteron. The valon structure itself is universal and arises from the perturbative dressing of the valence quark in QCD. Our results agree rather well with all of the relevant experimental data on g1p,n,d and gA/gV, and suggests that the sea quark contribution to the spin of proton is consistent with zero. It also reveals that while the total quark contribution to the spin of a valon, ΔΣvalon, is almost constant at Q2 ≥ 1 the gluon contribution grows with the increase of Q2 and hence requiring a sizable negative orbital angular momentum component Lz. This component along with the singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD . We speculate that gluon contribution to the spin content of the proton is about 60% for all Q2 values. Finally, we show that the size of gluon polarization and hence, Lz, is sensitive to the initial scale Q02
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 ...
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, ɡ1p, 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 ɡ1 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 < ΔΣ < 0.34 at 3 (GeV/c2 in M̅S̅ 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 ɡ1 proton and deuteron measurements. Preliminary results of a reevaluation of the gluon polarization Δɡ/ɡ 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 〈Δɡ/ɡ〉 = 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.
Lynn, J E
2015-01-01
I discuss our recent work on Green's function Monte Carlo (GFMC) calculations of light nuclei using local nucleon-nucleon interactions derived from chiral effective field theory (EFT) up to next-to-next-to-leading order (N$^2$LO). I present the natural extension of this work to include the consistent three-nucleon (3N) forces at the same order in the chiral expansion. I discuss our choice of observables to fit the two low-energy constants which enter in the 3N sector at N$^2$LO and present some results for light nuclei.
Lynn, J. E.
2016-03-01
I discuss our recent work on Green's function Monte Carlo (GFMC) calculations of light nuclei using local nucleon-nucleon interactions derived from chiral effective field theory (EFT) up to next-to-next-to-leading order (N2LO). I present the natural extension of this work to include the consistent three-nucleon (3N) forces at the same order in the chiral expansion. I discuss our choice of observables to fit the two low-energy constants which enter in the 3N sector at N2LO and present some results for light nuclei.
Directory of Open Access Journals (Sweden)
Lynn J. E.
2016-01-01
Full Text Available I discuss our recent work on Green’s function Monte Carlo (GFMC calculations of light nuclei using local nucleon-nucleon interactions derived from chiral effective field theory (EFT up to next-to-next-to-leading order (N2LO. I present the natural extension of this work to include the consistent three-nucleon (3N forces at the same order in the chiral expansion. I discuss our choice of observables to fit the two low-energy constants which enter in the 3N sector at N2LO and present some results for light nuclei.
Energy Technology Data Exchange (ETDEWEB)
Navratil, P; Caurier, E
2003-10-14
The authors calculate properties of A = 6 system using the accurate charge-dependent nucleon-nucleon (NN) potential at fourth order of chiral perturbation theory. By application of the ab initio no-core shell model (NCSM) and a variational calculation in the harmonic oscillator basis with basis size up to 16 {h_bar}{Omega} they obtain the {sup 6}Li binding energy of 28.5(5) MeV and a converged excitation spectrum. Also, they calculate properties of {sup 10}B using the same NN potential in a basis space of up to 8 {h_bar}{Omega}. The results are consistent with results obtained by standard accurate NN potentials and demonstrate a deficiency of Hamiltonians consisting of only two-body terms. At this order of chiral perturbation theory three-body terms appear. It is expected that inclusion of such terms in the Hamiltonian will improve agreement with experiment.
Studies of the nucleon structure in back-to-back SIDIS
Directory of Open Access Journals (Sweden)
Avakian H.
2016-01-01
Full Text Available The Deep Inelastic Scattering (DIS proved to be a great tool in testing of the theory of strong interactions, which was a major focus in last decades. Semi-Inclusive DIS (SIDIS, with detection of an additional hadron allowed first studies of 3D structure of the nucleon, moving the main focus from testing the QCD to understanding of strong interactions and quark gluon dynamics to address a number of puzzles accumulated in recent years. Detection of two hadrons in SIDIS, which is even more complicated, provides access to details of quark gluon interactions inaccessible in single-hadron SIDIS, providing a new avenue to study the complex nucleon structure. Large acceptance of the Electron Ion Collider, allowing detection of two hadrons, produced back-to-back in the current and target fragmentation regions, combined with clear separation of two regions, would provide a unique possibility to study the nucleon structure in target fragmentation region, and correlations of target and current fragmentation regions.
Progress in resolving charge symmetry violation in nucleon structure
Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia); Shanahan, P. E.; 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.
Transverse Spin Structure of the Nucleon from Lattice-QCD Simulations
International Nuclear Information System (INIS)
We present the first calculation in lattice QCD of the lowest two moments of transverse spin densities of quarks in the nucleon. They encode correlations between quark spin and orbital angular momentum. Our dynamical simulations are based on two flavors of clover-improved Wilson fermions and Wilson gluons. We find significant contributions from certain quark helicity flip generalized parton distributions, leading to strongly distorted densities of transversely polarized quarks in the nucleon. In particular, based on our results and recent arguments by Burkardt [Phys. Rev. D 72, 094020 (2005)], we predict that the Boer-Mulders function h1perpendicular, describing correlations of transverse quark spin and intrinsic transverse momentum of quarks, is large and negative for both up and down quarks
Distribution Functions of the Nucleon and Pion in the Valence Region
Holt, Roy J.; Roberts, Craig D.
2010-01-01
We provide an experimental and theoretical perspective on the behavior of unpolarized distribution functions for the nucleon and pion on the valence-quark domain; namely, Bjorken-x \\gtrsim 0.4. This domain is key to much of hadron physics; e.g., a hadron is defined by its flavor content and that is a valence-quark property. Furthermore, its accurate parametrization is crucial to the provision of reliable input for large collider experiments. We focus on experimental extractions of distributio...
International Nuclear Information System (INIS)
We present high statistics results for the structure of the nucleon from a mixed-action calculation using 2+1 flavors of asqtad sea and domain-wall valence fermions. We perform extrapolations of our data based on different chiral effective field theory schemes and compare our results with available information from phenomenology. We discuss vector and axial form factors of the nucleon, moments of generalized parton distributions, including moments of forward parton distributions, and implications for the decomposition of the nucleon spin.
Contribution of Quark Structure Term in Nucleon Electric and Magnetic Form Factors
Institute of Scientific and Technical Information of China (English)
WANG Hong-Min; ZHANG Ben-Ai
2004-01-01
The constituent quarks in the nucleon have always been considered as a point-like particle in the relativistic constituent quark model. However its calculation results of GnE agree poorly with the new experimental data. The electromagnetic structure of light front constituent quarks is considered in this paper. We find that the calculation results have good agreement with the new experimental data of GnE after considering the contribution of the quark structure term. This treatment seems to be able to improve the fit to experimental data of Gep/GMp, /Q2F2p/kpF1p,and Gen/GMn as well.
A novel nuclear dependence of nucleon-nucleon short-range correlations
Dai, Hongkai; Huang, Yin; Chen, Xurong
2016-01-01
A linear correlation is found between the magnitude of nucleon-nucleon short-range correlations and the nuclear binding energy per nucleon with pairing energy removed. By using this relation, the strengths of nucleon-nucleon short-range correlations of some unmeasured nuclei are predicted. Discussions on nucleon-nucleon pairing energy and nucleon-nucleon short-range correlations are made. The found nuclear dependence of nucleon-nucleon short-range correlations may shed some lights on the short-range structure of nucleus.
Study of the Nucleon Spin Structure by the Drell–Yan Process in the COMPASS-II Experiment
Quaresma, M
2012-01-01
The Parton Distribution Functions (PDFs) and the spin structure of the nucleon are important topics studied by the COMPASS experiment. The Drell–Yan (DY) process will be used in the future COMPASS-II measurements to access the Transverse Momentum Dependent PDFs (TMD PDFs). Studying the angular distributions of dimuons from the DY reactions with a negative pion beam with 190 GeV/c momentum and a transversely polarised proton target, we will be able to extract the azimuthal spin asymmetries and to access the various TMD PDFs, such as Sivers and Boer–Mulders functions. The start of the COMPASS DY experiment is scheduled for 2014. Three beam tests have been already performed, one of them in 2009 using a prototype hadron absorber downstream of the target, to understand the background reduction factors and the spectrometer response, and also to verify our results from Monte Carlo simulations. COMPASS aims at performing the first DY experiment with a transversely polarised target.
Contribution of Quark Structure Term in Nucleon Electric and Magnetic Form Factors
Institute of Scientific and Technical Information of China (English)
WANGHong-Min; ZHANGBen-Ai
2004-01-01
The constituent quarks in the nucleon have always been considered as a point-like particle in the relativisticconstituent quark model. However its calculation results of GEn agree poorly with the new experimental data. Theelectromagnetic structure of light front constituent quarks is considered in this paper. We find that the calculationresults have good agreement with the new experimental data of GEn after considering the contribution of the quarkstructure term. This treatment seems to be able to improve the fit to experimental data of GEp/GMp,√Q2F2p/kpF1p,and GEn/GMn as well.
Studies of the nucleon structure in back-to-back SIDIS
Avakian H.
2016-01-01
The Deep Inelastic Scattering (DIS) proved to be a great tool in testing of the theory of strong interactions, which was a major focus in last decades. Semi-Inclusive DIS (SIDIS), with detection of an additional hadron allowed first studies of 3D structure of the nucleon, moving the main focus from testing the QCD to understanding of strong interactions and quark gluon dynamics to address a number of puzzles accumulated in recent years. Detection of two hadrons in SIDIS, which is even more co...
High energy proton-proton elastic scattering at the Large Hadron Collider and nucleon structure
Luddy, Richard Joseph
To gain insight into the structure of the nucleon, we pursue the development of the phenomenological model of Islam et al. (IIFS model) for high energy elastic pp and p¯p scattering. We determine the energy dependence of the parameters of the IIFS model using the available elastic differential cross section data from SPS Collider and Tevatron and the known asymptotic behavior of sigmatot (s) and rho(s) from dispersion relation calculations and more recent analyses of Cudell et al. (COMPETE Collaboration). Next, we incorporate a high energy elastic valence quark-quark scattering amplitude into the model based on BFKL pomeron to describe small impact parameter (large | t|) pp collisions. Finally, we predict the pp elastic differential cross section at the unprecedented c.m. energy of s = 14.0 TeV at the Large Hadron Collider (LHC). This prediction assumes crucial significance---because of an approved experiment at LHC: TOTal and Elastic Measurement (TOTEM). The TOTEM group plans to measure pp elastic dsigma/dt at 14.0 TeV all the way from momentum transfer |t| = 0 to |t| ≃ 10 GeV 2. Their measurement will stringently test not only the diffraction and o-exchange descriptions of the original IIFS model, but also the additional valence quark-quark scattering contribution that we find to be dominant for large |t|. Successful quantitative verification of the predicted dsigma/dt will mean that our picture of the nucleon with an outer cloud of qq¯ condensed ground state, an inner core of topological baryonic charge, and a still smaller core of massless valence quarks provides a realistic description of nucleon structure.
Chang, Wen-Chen
2016-01-01
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.
Chang, Wen-Chen
2016-02-01
The observation of the violation of Lam-Tung relation in the πN 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.
Advances on statistical/thermodynamical models for unpolarized structure functions
International Nuclear Information System (INIS)
During the eights and nineties many statistical/thermodynamical models were proposed to describe the nucleons’ structure functions and distribution of the quarks in the hadrons. Most of these models describe the compound quarks and gluons inside the nucleon as a Fermi / Bose gas respectively, confined in a MIT bag with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries -d/-u and -d–-u.
Litvinova, Elena
2016-04-01
The relativistic particle-vibration coupling (RPVC) model is extended by the inclusion of isospin-flip excitation modes into the phonon space, introducing a new mechanism of dynamical interaction between nucleons with different isospin in the nuclear medium. Protons and neutrons exchange by collective modes which are formed by isovector π and ρ-mesons, in turn, softened considerably because of coupling to nucleons of the medium. These modes are investigated within the proton-neutron relativistic random phase approximation (pn-RRPA) and relativistic proton-neutron time blocking approximation (pn-RTBA). The appearance of isospin-flip states with sizable transition probabilities at low energies points out that they are likely to couple to the single-particle degrees of freedom and, in addition to isoscalar low-lying phonons, to modify their spectroscopic characteristics. Such a coupling is quantified for the shell structure of 100,132Sn and found significant for the location of the dominant single-particle states.
International Nuclear Information System (INIS)
The soft-rotator model is used for the analysis of the nuclear level structure and the nucleon interaction data for 52Cr. In this work, the optical model calculations of scattering cross sections are self-consistent, since the parameters of the nuclear Hamiltonian are determined by adjusting the energies of the collective levels to the evaluated nuclear structure data prior to the optical model calculation. The model succeeds in describing the low-lying experimental collective levels up to 3.5 MeV and the nucleon interaction experimental data up to 150 MeV for 52Cr. (author)
Sub-structures in hadrons and proton structure functions
Arash, Firooz; Khorramian, Ali N.
2001-04-01
We calculate the partonic structure of constituent quark in the Next-to-Leading Order. Using a convolution method, Structure function of proton is presented. While the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contributions coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the SU(2) symmetry breaking of the nucleon sea and the observed violation of Gottfried sum rule. Excellent agreement with data in a wide range of x = [10 -6, 1] and Q2 = [0.5, 5000] GeV2 for Fp2 is reached.
Hadronic Structure Functions from the Universal and the Basic Structures
Arash, F.
2005-04-01
It is shown that there is a basic structure common to all hadrons, which is generated perturbatively in QCD. Basically, it is a valence quark with its own cloud of quarks and gluons, a quasi-particle that we will call it a valon. In the valon representation, structure functions of nucleon and pion are calculated and is shown that there is an excellent agreement between the data and the model results in a wide range of kinematics. Calculation of the polarized structure functions also shows that there is a sizeable orbital angular momentum contribution to the spin of a valon coming from the partonic cloud.
Electromagnetic Structure and Reactions of Few-Nucleon Systems in χEFT
Schiavilla R.; Girlanda L.; Pastore S.; Viviani M.
2010-01-01
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 captu...
A lattice evaluation of four-quark operators in the nucleon
International Nuclear Information System (INIS)
Nucleon matrix elements of various four-quark operators are evaluated in quenched lattice QCD using Wilson fermions. Some of these operators give rise to twist-four contributions to nucleon structure functions. Furthermore, they bear valuable information about the diquark structure of the nucleon. Mixing with lower-dimensional operators is avoided by considering appropriate representations of the flavour group. We find that for a certain flavour combination of baryon structure functions, twist-four contributions are very small. This suggests that twist-four effects for the nucleon might be much smaller than mp2/Q2. (orig.)
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.
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-10-01
This report summarizes the work on experimental research in intermediate energy nuclear physics carried out by New Mexico State University from April 1, 1994, through March 31, 1996 under a grant from the US Department of Energy. During this period we began phasing out our programs of study of pion-nucleus and pion-nucleon interaction and of nucleon-nucleus charge-exchange reactions, which have been our major focus of the past two or three years. At the same time we continued moving in a new direction of research on studies of the internal structure of nucleons and nuclei in terms of quarks and gluons. The pion and nucleon work has been aimed at improving our understanding of the nature of pion and proton interactions in the nuclear medium and of various aspects of nuclear structure. The studies of the quark-gluon structure of nucleons are aimed at clarifying such problems as the nature of the quark sea and the relation of the nucleon spin to the spins of the quarks within the nucleon, questions which are of a very fundamental nature.
International Nuclear Information System (INIS)
This report summarizes the work on experimental research in intermediate energy nuclear physics carried out by New Mexico State University from April 1, 1994, through March 31, 1996 under a grant from the US Department of Energy. During this period we began phasing out our programs of study of pion-nucleus and pion-nucleon interaction and of nucleon-nucleus charge-exchange reactions, which have been our major focus of the past two or three years. At the same time we continued moving in a new direction of research on studies of the internal structure of nucleons and nuclei in terms of quarks and gluons. The pion and nucleon work has been aimed at improving our understanding of the nature of pion and proton interactions in the nuclear medium and of various aspects of nuclear structure. The studies of the quark-gluon structure of nucleons are aimed at clarifying such problems as the nature of the quark sea and the relation of the nucleon spin to the spins of the quarks within the nucleon, questions which are of a very fundamental nature
Electromagnetic Structure and Reactions of Few-Nucleon Systems in χEFT
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 eﬀective ﬁeld theory (χEFT. 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.
Energy Technology Data Exchange (ETDEWEB)
Deur, Alexandre
2009-12-01
We discuss the Jefferson Lab low momentum transfer data on moments of the nucleon spin structure functions $g_1$ and $g_2$ and on single charged pion electroproduction off polarized proton and polarized neutron. A wealth of data is now available, while more is being analyzed or expected to be taken in the upcoming years. Given the low momentum transfer selected by the experiments, these data can be compared to calculations from Chiral Perturbation theory, the effective theory of strong force that should describe it at low momentum transfer. The data on various moments and the respective calculations do not consistently agree. In particular, experimental data for higher moments disagree with the calculations.The absence of contribution from the $\\Delta$ resonance in the various observables was expected to facilitate the calculations and hence make the theory predictions either more robust or valid over a larger $Q^2$ range. Such expectation is verified only for the Bjorken sum, but not for other observables in which the $\\Delta$ is suppressed. Preliminary results on pion electroproduction off polarized nucleons are also presented and compared to phenomenological models for which contributions from different resonances are varied. Chiral Perturbation calculations of these observables, while not yet available, would be valuable and, together with these data, would provide an extensive test of the effective theory.
Del Dotto, Alessio; Salmè, Giovanni; Scopetta, Sergio
2016-01-01
Poincare' covariant definitions for the spin-dependent spectral function and for the momentum distributions within the light-front Hamiltonian dynamics are proposed for a three-fermion bound system, starting from the light-front wave function of the system. The adopted approach is based on the Bakamjian-Thomas construction of the Poincare' generators, that allows one to easily import the familiar and wide knowledge on the nuclear interaction into a light-front framework. The proposed formalism can find useful applications in refined nuclear calculations, like the ones needed for evaluating the EMC effect or the semi-inclusive deep inelastic cross sections with polarized nuclear targets, since remarkably the light-front unpolarized momentum distribution by definition fulfills both normalization and momentum sum rules. It is also shown a straightforward generalization of the definition of the light-front spectral function to an A-nucleon system.
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.
Deep inelastic scattering operators in meson-nucleon theory
International Nuclear Information System (INIS)
Nonrelativistic meson-nucleon theory of deep-inelastic scattering (DIS) of leptons on the deuteron is considered. Explicit expressions of nonrelativistic composed operators of DIS in the framework of the operator product expansion method are obtained in terms of interacting meson-nucleon fields. An analytic expression of the second moment of the structure functions (up to g2 accuracy( is obtained with particular emphasis on self-energy contributions and meson exchange currents (MEC). Deuteron moments are shown to be expressed in terms of constituent (nucleons and mesons) observables. The energy conservation law is restored by taking into account MEC
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, $\\frac{\\la x \\ra^{(3)}}{\\la x \\ra^{(8)}} = 0.39(1)(4)$.
Tau lepton polarization in quasielastic neutrino-nucleon scattering
Konstantin S. KuzminDubna, JINR; Lyubushkin, Vladimir V.; Naumov, Vadim A.
2015-01-01
We derive structure functions for the quasielastic production of octet baryons in neutrino and antineutrino interactions with nucleons and study the polarization of tau leptons produced in the $\\Delta{Y}=0$ reactions. Possible impact of the charged second-class currents is investigated by adopting a simple phenomenological parametrization for the nonstandard scalar and tensor nucleon form factors. Our choice of the unknown parameters is made to satisfy the limits obtained in the (anti)neutrin...
Sub-structures in hadrons and proton structure functions
International Nuclear Information System (INIS)
We calculate the partonic structure of constituent quark in the Next-to-Leading Order. Using a convolution method, Structure function of proton is presented. While the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contributions coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the SU(2) symmetry breaking of the nucleon sea and the observed violation of Gottfried sum rule. Excellent agreement with data in a wide range of x = [10-6, 1] and Q2 = [0.5, 5000] GeV2 for Fp2 is reached
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.
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.
Rowe, D. J.; McCoy, A. E.; Caprio, M. A.
2016-03-01
The nuclear collective models introduced by Bohr, Mottelson and Rainwater, together with the Mayer-Jensen shell model, have provided the central framework for the development of nuclear physics. This paper reviews the microscopic evolution of the collective models and their underlying foundations. In particular, it is shown that the Bohr-Mottelson models have expressions as macroscopic limits of microscopic models that have precisely defined expressions in many-nucleon quantum mechanics. Understanding collective models in this way is especially useful because it enables the analysis of nuclear properties in terms of them to be revisited and reassessed in the light of their microscopic foundations.
Alvioli, Massimiliano; Morita, Hiko
2016-01-01
The two-nucleon momentum distributions have been calculated for nuclei up to A=40 and various values of the relative and center-of-mass momenta and angle between them. For complex nuclei a parameter-free linked-cluster expansion, based upon a realistic local two-nucleon interaction of the Argonne family and variational wave function featuring central, tensor, spin and iso-spin correlations, has been used. The obtained results show that: 1) independently of the mass number A, at values of the relative momentum k_rel> 2 fm^{-1} the proton-neutron momentum distributions for back-to-back (BB) nucleons (K_cm=0) exhibit the factorization property n_A^{pn}(k_rel,K_cm=0)=C_A^{pn} n_D(k_rel) n_{cm}^{pn}(K_cm=0), where n_D is the deuteron momentum distribution, n_{cm}^{pn}(K_{cm}=0) the momentum distribution of the c.m. motion of the pair and C_A^{pn} the nuclear contact measuring the number of BB pn pairs with deuteron-like momenta; 2) the values of the proton-neutron nuclear contact C_A^{pn} are obtained in a model-i...
How well do we know the neutron structure function?
Arrington, J.; Rubin, J. G.; Melnitchouk, W.
2011-01-01
We present a detailed analysis of the uncertainty in the neutron F2n structure function extracted from inclusive deuteron and proton deep-inelastic scattering data. The analysis includes experimental uncertainties as well as uncertainties associated with the deuteron wave function, nuclear smearing, and nucleon off-shell corrections. Consistently accounting for the Q^2 dependence of the data and calculations, and restricting the nuclear corrections to microscopic models of the deuteron, we fi...
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.
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
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...
First moment of the flavour octet nucleon parton distribution function using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Constantinou, Martha; Hadjiyiannakou, Kyriakos; Koutsou, Giannis [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Dinter, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Institute for Advanced Study DIAS; Jansen, Karl [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Vaquero, Alejandro [INFN, Sezione di Milano-Bicocca, Milano (Italy); Collaboration: European Twisted Mass Collaboration
2015-03-15
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle {sup (8)}{sub μ{sup 2}=4} {sub GeV{sup 2}}. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed by S. Dinter et. al. (2012). We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)}) (with left angle x right angle {sup (3)} the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)})=0.39(1)(4).
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.
Maris, Pieter; Vary, James P.; Navratil, Petr
2012-01-01
We solve the ab initio no-core shell model (NCSM) in the complete Nmax = 8 basis for A = 7 and A = 8 nuclei with two-nucleon and three-nucleon interactions derived within chiral effective field theory (EFT). We find that including the chiral EFT three-nucleon interaction in the Hamiltonian improves overall good agreement with experimental binding energies, excitation spectra, transitions and electromagnetic moments. We predict states that exhibit sensitivity to including the chiral EFT three-...
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 l...
International Nuclear Information System (INIS)
The soft-rotator model (SRM) and a coupled-channels method based on the coupling scheme built on the wave functions of the SRM were applied for a consistent analysis of the nuclear level structure, B(E2) and the nucleon interaction data of 56Fe. The model could describe the experimental collective levels of 56Fe up to the excitation energy of 5.5 MeV successfully. Relativistic kinematics and global optical potential form, consistent with nuclear matter theory and Dirac phenomenology, were used in coupled-channels optical model approach to overcome problems left in our previous work. The available nucleon interaction experimental data up to 160 MeV and B(E2) γ-transitions were described satisfactorily. (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 proposal is that m...
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
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.
Husimi distribution for nucleon tomography
Directory of Open Access Journals (Sweden)
Hatta Yoshitaka
2016-01-01
Full Text Available We define the QCD Husimi distribution as the phase space distribution of partons inside the nucleon. Compared to the more well-known Wigner distribution, the Husimi distribution is better behaved and positive. It thus allows for a probabilistic interpretation and can be used to define the ‘entropy’ of the nucleon as a measure of complexity of the partonic structure. A possible connection to the Color Glass Condensate approach at small-x is also discussed.
Off-shell Corrections and Moments of the Deep Inelastic Nuclear Structure Functions
Cothran, C D; Liuti, S
1998-01-01
We present an improved method for handling off-shell effects in deep inelastic nuclear scattering. With a firm understanding of the effects of the nuclear wave function, including these off-shell corrections as well as binding and nucleon-nucleon correlations, we can begin to examine the role of QCD in nuclei through an analysis of the moments of the nuclear structure function. Our analysis is aimed at extracting the Q^2 dependence of the moments of the nucleon structure function by using the recent high x world Iron data and by properly removing nuclear effects from the perturbative contribution. In addition, we compare quantitatively the behavior of the extracted moments with a simple O(1/Q^2) phenomenological form and we determine the mass term for this parametrization.
Statistical Error analysis of Nucleon-Nucleon phenomenological potentials
Perez, R Navarro; Arriola, E Ruiz
2014-01-01
Nucleon-Nucleon potentials are commonplace in nuclear physics and are determined from a finite number of experimental data with limited precision sampling the scattering process. We study the statistical assumptions implicit in the standard least squares fitting procedure and apply, along with more conventional tests, a tail sensitive quantile-quantile test as a simple and confident tool to verify the normality of residuals. We show that the fulfilment of normality tests is linked to a judicious and consistent selection of a nucleon-nucleon database. These considerations prove crucial to a proper statistical error analysis and uncertainty propagation. We illustrate these issues by analyzing about 8000 proton-proton and neutron-proton scattering published data. This enables the construction of potentials meeting all statistical requirements necessary for statistical uncertainty estimates in nuclear structure calculations.
The Structure of the Nucleon and it's Excited States
Energy Technology Data Exchange (ETDEWEB)
None
1995-02-20
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
Intrinsic charm content of the nucleon and charmness-nucleon sigma term
Duan, Shaorong; Saghai, B
2016-01-01
In the extended chiral constituent quark model, the intrinsic $c \\bar{c}$ content of the nucleon is investigated. The probabilities of the quark-antiquark components in the nucleon wave functions are calculated by taking the nucleon to be admixtures of three- and five-quark components, with the relevant transitions handled {\\it via} the $^{3}$P$_{0}$ mechanism. Predictions for the probability of the $c \\bar{c}$ in the nucleon wave function and the charmness-nucleon sigma term are presented. Our numerical results turn out to be consistent with the predictions from various other approaches reported in the literature.
Intrinsic charm content of the nucleon and charmness-nucleon sigma term
Duan, Shaorong; An, C. S.; Saghai, B.
2016-06-01
In the extended chiral constituent quark model, the intrinsic c c ¯ content of the nucleon is investigated. The probabilities of the quark-antiquark components in the nucleon wave functions are calculated by taking the nucleon to be admixtures of three- and five-quark components, with the relevant transitions handled via the 3P0 mechanism. Predictions for the probability of the c c ¯ in the nucleon wave function and the charmness-nucleon sigma term are presented. Our numerical results turn out to be consistent with the predictions from various other approaches reported in the literature.
Nucleon-nucleon theory and phenomenology
International Nuclear Information System (INIS)
This project involves five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 0-1200 MeV range that can be used by all nucleon-nucleon reseachers
DEFF Research Database (Denmark)
Sinden, Richard R.; E. Pearson, Christopher; N. Potaman, Vladimir;
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...
Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order
Energy Technology Data Exchange (ETDEWEB)
Epelbaum, E.; Krebs, H. [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany); Meissner, U.G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Forschungszentrum Juelich, Institut fuer Kernphysik, Institute for Advanced Simulation, and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, JARA - High Performance Computing, Juelich (Germany)
2015-05-15
We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of previous works (Nucl. Phys. A 747, 362 (2005) and Phys. Rev. C 68, 041001 (2003)) is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in (Nucl. Phys. A 747, 362 (2005)) to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c{sub i} and d{sub i} determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also employ a simple approach for estimating the theoretical uncertainty in few-nucleon calculations from the truncation of the chiral expansion that replaces previous reliance on cutoff variation. (orig.)
HERMES Results on the 3D Imaging of the Nucleon
Pappalardo, L. L.
2016-07-01
It the last decades, a formalism of transverse momentum dependent parton distribution functions (TMDs) and of generalised parton distributions (GPDs) has been developed in the context of non-perturbative QCD, opening the way for a tomographic imaging of the nucleon structure. TMDs and GPDs provide complementary three-dimensional descriptions of the nucleon structure in terms of parton densities. They thus contribute, with different approaches, to the understanding of the full phase-space distribution of partons. A selection of HERMES results sensitive to TMDs is presented.
Transversity of quarks in a nucleon
Indian Academy of Sciences (India)
K Bora; D K Choudhury
2003-11-01
The transversity distribution of quarks in a nucleon is one of the three fundamental distributions, that characterize nucleon’s properties in hard scattering processes at leading twist (twist 2). It measures the distribution of quark transverse spin in a nucleon polarized transverse to its (inﬁnite) momentum. It is a chiral-odd twist-two distribution function – gluons do not couple to it. Quarks in a nucleon/hadron are relativistically bound and transversity is a measure of the relativistic nature of bound quarks in a nucleon. In this work, we review some important aspects of this less familiar distribution function which has not been measured experimentally so far.
Nucleon-pion-state contributions in the determination of the nucleon axial charge
Bar, Oliver
2015-01-01
The nucleon-pion-state contributions to QCD 2- and 3-point functions used in the calculation of the nucleon axial charge are studied in chiral perturbation theory. For sufficiently small quark masses and large volumes the nucleon-pion states are expected to have smaller total energy than the single-particle excited states. To leading order in chiral perturbation theory the results do not depend on low-energy constants associated with the interpolating nucleon fields and apply to local as well as smeared interpolators. The nucleon-pion-state contribution is found to be at the few percent level.
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.
Probing the transversity spin structure of a nucleon in neutrino-production of a charmed meson
Pire, B; Wagner, J
2016-01-01
Including O(m_c) terms in the coefficient functions and/or O(m_D) twist 3 contributions in the heavy meson distribution amplitudes leads to a non-zero transverse amplitude for exclusive neutrino production of a D pseudoscalar charmed meson on an unpolarized target. We work in the framework of the collinear QCD approach where chiral-odd transversity generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions.
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 ħω 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.
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 ...
Energy Technology Data Exchange (ETDEWEB)
Zheng, Xiaochao [Univ. of Virginia, Charlottesville, VA (United States). Jesse Beams Lab.
2016-03-10
spectrometer, called “SoLID”. Once built, SoLID can be used for other topics such as using PVDIS on a proton target to measure the valence quark distributions, using PVDIS on a polarized target to measure new electro-weak interference structure functions of the nucleon, and semi-inclusive deep inelastic scattering experiments. SoLID will greatly enhance the exploration potential of JLab. The proposed program will first focus on completion of the 6 GeV PVDIS experiment, its data analysis and publishing physics results. This 6 GeV experiment will explore whether precision PVDIS measurements are feasible, will set limits on the hadronic physics effects, and will improve our knowledge on the quark neutral weak couplings, optimally by a factor of six. Starting early 2010, efforts will be spent on preparation for the 11 GeV program, focusing on simulations of SoLID, optimization and construction of the SoLID detector package, and studies of the polarized ^{3}He target and its improvements. Funding support for the whole program is requested here.
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
Nuclear medium modification of the F2 structure function
Athar, M Sajjad; Vacas, M J Vicente
2009-01-01
We study the nuclear effects in the electromagnetic structure function $F_{2}(x, Q^2)$ in nuclei in the deep inelastic lepton nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. The ratios $R_{F2}^A(x,Q^2)=\\frac{2F_2^A(x,Q^2)}{AF_{2}^{Deut}(x,Q^2)}$ are obtained and compared with the recent JLAB results for light nuclei that show a non trivial A dependence.
Structure functions of nuclei in the ''instant'' form of dynamics
International Nuclear Information System (INIS)
Convolution formulas for the inelastic structure functions of a nucleus are derived using the ''instant'' form of relativistic particle dynamics, and are contrasted with other convolution approaches. Using only physical nucleon constituents and harmonic oscillator shell model wave functions, the magnitude of the dip in the European Muon Collaboration ratio in the intermediate range of x is reproduced. The calculations of this ratio fail to come back up towards unity as x decreases below 0.4, and possible reasons for this are discussed
Neutrino-production of a charmed meson and the transverse spin structure of the nucleon
Pire, B.; Szymanowski, L.
2015-01-01
International audience 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 νN ...
Spin observables in nucleon-deuteron scattering and three-nucleon forces
Ishikawa, S; Iseri, Y
2002-01-01
Three-nucleon forces, which compose an up-to-date subject in few-nucleon systems, provide a good account of the triton binding energy and the cross section minimum in proton-deuteron elastic scattering, while do not succeed in explaining spin observables such as the nucleon and deuteron analyzing powers, suggesting serious defects in their spin dependence. We study the spin structure of nucleon-deuteron elastic amplitudes by decomposing them into spin-space tensors and examine effects of three-nucleon forces to each component of the amplitudes obtained by solving the Faddeev equation. Assuming that the spin-scalar amplitudes dominate the others, we derive simple expressions for spin observables in the nucleon-deuteron elastic scattering. The expressions suggest that a particular combination of spin observables in the scattering provides direct information of scalar, vector, or tensor component of the three-nucleon forces. These effects are numerically investigated by the Faddeev calculation.
Comparison of moments from the valence structure function with QCD predictions
International Nuclear Information System (INIS)
Moments (both ordinary and Nachtmann) of the nucleon valence structure function measured in high Q2 γFe scattering are presented, supplemented by data from deep inelastic eD scattering. These data seem to agree with QCD predictions for vector gluons. The QCD parameter Λ is found to be of the order 0.5 GeV. (Auth.)
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...
Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC
Energy Technology Data Exchange (ETDEWEB)
L. Frankfurt, M. Strikman, C. Weiss
2011-03-01
We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/\\gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process.
QCD and Symmetries related to nucleon structure and strongly interacting matter
International Nuclear Information System (INIS)
We discuss the impact of the symmetries of quantum chromodynamics (QCD) on the observed properties of hadrons and strongly interacting matter. We first introduce the fundamental color gauge symmetry insisting on its non perturbative aspect at low energy. Particular emphasis is put on the spontaneous breaking of chiral symmetry and its numerous consequences. Operational approaches, such as chiral perturbation theory or QCD sum rules, allowing to implement this crucial symmetry at the hadronic level are presented. We then explore the consequences of chiral restoration at finite baryonic density and/or temperature on the properties of in-medium hadrons in connection with experimental programs. Finally we give a short discussion of the phase structure of QCD in connection with chiral symmetry and the center symmetry associated with the confinement/deconfinement transition. This document includes the slides of the presentation. (author)
Study of nucleon-nucleon and hyperon-nucleon interaction
Energy Technology Data Exchange (ETDEWEB)
Shimizu, Kiyotaka [Department of Physics, Sophia University, Tokyo (Japan); Takeuchi, Sachiko [Japan College of Social Work, Kiyose (Japan); Buchmann, A.J. [Institute for Theoretical Physics, University of Tuebinge (Germany)
2000-04-01
In this paper we review recent investigations of nucleon-nucleon and hyperon-nucleon interactions employing a non-relativistic quark cluster model. We concentrate mainly on the short and medium-range behavior of the baryon-baryon interaction based on the one-gluon and meson exchange potentials. The chiral quark model based on pion and sigma exchange between quarks is also discussed. We also review a study of the deuteron and its electromagnetic properties in a quark model with exchange currents. (author)
Nucleon Strangeness and Unitarity
Musolf, M. J.; Hammer, H. -W.; D. Drechsel(Institut f. Kernphysik, Mainz)
1996-01-01
The strange-quark vector current form factors of the nucleon are analyzed within the framework of dispersion relations. Particular attention is paid to contributions made by $K\\bar{K}$ intermediate states to the form factor spectral functions. It is shown that, when the $K\\bar{K}\\to N\\bar{N}$ amplitude is evaluated in the Born approximation, the $K\\bar{K}$ contributions are identical to those arising from a one-loop calculation and entail a serious violation of unitarity. The mean square stra...
On the similarity of the parton distributions in nuclei with more than three nucleons
Smirnov, G I
1996-01-01
It is shown that the latest results from NMC and E665 on the $F_2^A(x)/F_2^{D}(x)$ obtained in the shadowing region, bring new evidence of the universal $A$ -- dependence of distorsions of a free nucleon structure function by nuclear medium. The universality holds in the entire $x$ -range and can be explained as a saturation of the distortions of the parton distributions in a four-nucleon system.
Energy Technology Data Exchange (ETDEWEB)
Cornelis de Jager
2004-09-01
The experimental and theoretical status of elastic electron scattering from the nucleon is reviewed. As a consequence of new experimental facilities, data of unprecedented precision have recently become available for the electromagnetic and the strange form factors of the nucleon.
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\
Spin–orbit correlations in the nucleon
International Nuclear Information System (INIS)
We investigate the correlations between the quark spin and orbital angular momentum inside the nucleon. Similarly to the Ji relation, we show that these correlations can be expressed in terms of specific moments of measurable parton distributions. This provides a whole new piece of information about the partonic structure of the nucleon
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
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.
Burkert, Volker D
2016-01-01
Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and $\\Delta$ states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger Equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of $Q^2 > 1.5GeV^2$. In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degre...
Burkert, Volker D.
2016-10-01
Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and Δ states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of Q^2 > 1.5 GeV^2. In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degrees of freedom underlying the excited states and their dependence on the distance scale probed.
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; ...
Multi-functional composite structures
Energy Technology Data Exchange (ETDEWEB)
Mulligan, Anthony C.; Halloran, John; Popovich, Dragan; Rigali, Mark J.; Sutaria, Manish P.; Vaidyanathan, K. Ranji; Fulcher, Michael L.; Knittel, Kenneth L.
2010-04-27
Fibrous monolith processing techniques to fabricate multifunctional structures capable of performing more than one discrete function such as structures capable of bearing structural loads and mechanical stresses in service and also capable of performing at least one additional non-structural function.
Multi-functional composite structures
Energy Technology Data Exchange (ETDEWEB)
Mulligan, Anthony C.; Halloran, John; Popovich, Dragan; Rigali, Mark J.; Sutaria, Manish P.; Vaidyanathan, K. Ranji; Fulcher, Michael L.; Knittel, Kenneth L.
2004-10-19
Fibrous monolith processing techniques to fabricate multifunctional structures capable of performing more than one discrete function such as structures capable of bearing structural loads and mechanical stresses in service and also capable of performing at least one additional non-structural function.
Experimental progress and status on nucleon electromagnetic form factors
Directory of Open Access Journals (Sweden)
Gao H.
2016-01-01
Full Text Available Nucleon electromagnetic form factors are the fundamental quantities that are related to a two-dimensional view of the charge and magnetization distribution in the nucleon. They are essential in understanding the nucleon electromagnetic structure. In this article, we briefly summarize the recent experimental progress on this topic, and introduce several experiments related to the nucleon electromagnetic form factors in the near future.
Energy Technology Data Exchange (ETDEWEB)
Yokosawa, A.
1985-01-01
We review experimental results concerning polarization phenomena in nucleon-nucleon scattering in which both the elastic scattering and hadron-production reaction are included. We also present summary of S = 0 dibaryon resonances and candidates by reviewing experimental data in the nucleon-nucleon system, ..gamma..d channel, ..pi..d elastic scattering, pp ..-->.. ..pi..d channel, deuteron break-up reactions, and narrow structures in missing-mass spectra. 93 refs., 26 figs.
Comparison of Relativistic Nucleon-Nucleon Interactions
Allen, T. W.; Payne, G. L.; Polyzou, Wayne N.
2000-01-01
We investigate the difference between those relativistic models based on interpreting a realistic nucleon-nucleon interaction as a perturbation of the square of a relativistic mass operator and those models that use the method of Kamada and Gl\\"ockle to construct an equivalent interaction to add to the relativistic mass operator. Although both models reproduce the phase shifts and binding energy of the corresponding non-relativistic model, they are not scattering equivalent. The example of el...
A-dependence of weak nuclear structure functions
Energy Technology Data Exchange (ETDEWEB)
Haider, H.; Athar, M. Sajjad [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Simo, I. Ruiz [Dipartimento di Fisica, Universitá degli studi di Trento Via Sommarive 14, Povo (Trento) I-38123 (Italy)
2015-05-15
Effect of nuclear medium on the weak structure functions F{sub 2}{sup A}(x, Q{sup 2}) and F{sub 3}{sup A}(x, Q{sup 2}) have been studied using charged current (anti)neutrino deep inelastic scattering on various nuclear targets. Relativistic nuclear spectral function which incorporate Fermi motion, binding and nucleon correlations are used for the calculations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, F{sub i}{sup A}/F{sub i}{sup proton} and F{sub i}{sup A}/F{sub i}{sup deuteron}(i=2,3, A={sup 12}C, {sup 16}O, CH and H{sub 2}O) are obtained.
Neutron-star matter within the energy-density functional theory and neutron-star structure
Energy Technology Data Exchange (ETDEWEB)
Fantina, A. F.; Chamel, N.; Goriely, S. [Institut d' Astronomie et d' Astrophysique, CP226, Université Libre de Bruxelles (ULB), 1050 Brussels (Belgium); Pearson, J. M. [Dépt. de Physique, Université de Montréal, Montréal (Québec), H3C 3J7 (Canada)
2015-02-24
In this lecture, we will present some nucleonic equations of state of neutron-star matter calculated within the nuclear energy-density functional theory using generalized Skyrme functionals developed by the Brussels-Montreal collaboration. These equations of state provide a consistent description of all regions of a neutron star. The global structure of neutron stars predicted by these equations of state will be discussed in connection with recent astrophysical observations.
Hidden Color and the b1 Structure Function of the Deuteron
International Nuclear Information System (INIS)
The b1 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. (author)
Few Nucleon Scattering and Three Nucleon Force
Sekiguchi, Kimiko
2009-10-01
One recent topic of the few-nucleon system studies to explore the properties of three nucleon forces (3NFs) that appear in the system more than two nucleons. The 3NFs arise naturally in the standard meson exchange picture as well as in the more recent concept of chiral effective field theory. These forces are considered to be one key element to understand the nuclear phenomena in a consistent way. However there had been little knowledge with which to constrain the 3NFs. That is due to the fact that 3NFs are relatively weak compared to the nucleon--nucleon (NN) forces and then their effects are easily masked. Few nucleon scattering is one of the most promising tool for the 3NF study, because this system provides a rich set of energy dependent spin observables and differential cross sections. In the end of 1990's two theory groups reported the rigorous numerical Faddeev calculations incorporating 2π-exchange 3NFs in elastic Nd scattering at intermediate energies (E/A ˜100 MeV), and they suggested that the difference found in the cross section minima is the signature of 3NF effects. Since then experimental studies of intermediate-energy pd/nd elastic scattering and pd breakup reactions have been performed by groups at RIKEN, RCNP, KVI, IUCF and Uppsala. Theoretically addition of 3NFs other than 2π exchange types, and/or relativistic treatment, and completely new approach based on chiral effective field theory are now in progress. The importance of 3NFs has also been noted in other instances; e.g. descriptions of the binding energies of light mass nuclei and the empirical saturation point of symmetric nuclear matter. It is clear that the testing of 3NF models has just begun. In the presentation, recent progress in the 3NF study with few nucleon scattering at intermediate energies will be given.
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.
Tvaskis, V; Niculescu, I; Abbott, D; Adams, G S; Afanasev, A; Ahmidouch, A; Angelescu, T; Arrington, J; Asaturyan, R; Avery, S; Baker, O K; Benmouna, N; Berman, B L; Biselli, A; Blok, H P; Boeglin, W U; Bosted, P E; Brash, E; Breuer, H; Chang, G; Chant, N; Christy, M E; Connell, S H; Dalton, M M; Danagoulian, S; Day, D; Dodario, T; Dunne, J A; Dutta, D; Khayari, N El; Ent, R; Fenker, H C; Frolov, V V; Gaskell, D; Garrow, K; Gilman, R; Gueye, P; Hafidi, K; Hinton, W; Holt, R J; Horn, T; Huber, G M; Jackson, H; Jiang, X; Jones, M K; Joo, K; Kelly, J J; Keppel, C E; Kuhn, J; Kinney, E; Klein, A; Kubarovsky, V; Liang, M; Liang, Y; Lolos, G; Lung, A; Mack, D; Malace, S; Markowitz, P; Mbianda, G; McGrath, E; Mckee, D; McKee, P; Meekins, D G; Mkrtchyan, H; Moziak, B; Napolitano, J; Navasardyan, T; Niculescu, G; Nozar, M; Ostapenko, T; Papandreou, Z; Potterveld, D; Reimer, P E; Reinhold, J; Roche, J; Rock, S E; Schulte, E; Segbefia, E; Smith, C; Smith, G R; Stoler, P; Tadevosyan, V; Tang, L; Telfeyan, J; Todor, L; Ungaro, M; Uzzle, A; Vidakovic, S; Villano, A; Vulcan, W F; Wang, M; Warren, G; Wesselmann, F; Wojtsekhowski, B; Wood, S A; Xu, C; Yan, C; Yuan, L; Zheng, X; Zihlmann, B; Zhu, H
2016-01-01
Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the quark dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available for the longitudinal structure function in particular. Here we present separated structure functions for hydrogen and deuterium at low four--momentum transfer squared, Q^2< 1 GeV^2, and compare these with parton distribution parameterizations and a k_T factorization approach. While differences are found, the parameterizations generally agree with the data even at the very low Q^2 scale of the data. The deuterium data show a smaller longitudinal structure function, and smaller ratio of longitudinal to transverse cross section R, than the proton. This suggests either an unexpected difference in R for the proton and neutron or a suppression of the gluonic distribution in nuclei.
Tensor-polarized structure functions: Tensor structure of deuteron in 2020's
Kumano, S.
2014-10-01
We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones (F1, F2, g1, g2) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are b1, b2, b3, and b4 in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist- two functions are related by the Callan-Gross type relation b2 = 2xb1 in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of b1-4 from a hadron tensor Wμν. Second, a sum rule is explained for b1, and possible tensor-polarized distributions are discussed by using HERMES data in order to propose future experimental measurements and to compare them with theoretical models. A proposal was approved to measure b1 at the Thomas Jefferson National Accelerator Facility (JLab), so that much progress is expected for b1 in the near future. Third, formalisms of polarized proton-deuteron Drell-Yan processes are explained for probing especially tensor- polarized antiquark distributions, which were suggested by the HERMES data. The studies of the tensor-polarized structure functions will open a new era in 2020's for tensor-structure studies in terms of quark and gluon degrees of freedom, which are very different from ordinary descriptions in terms of nucleons and mesons.
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...
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.
Nucleon-nucleon scattering phase shifts
International Nuclear Information System (INIS)
Here are presented 0 to 800 MeV nucleon-nucleon elastic and inelastic phase parameters derived by several groups: Arndt and Roper; Hoshizaki; Bugg; Bystricky, Lechanoine, and Lehar; and Bryan, Clark, and VerWest. Resonant-like behavior appears in the 1D2 and 3F3 states above the inelastic threshold in Hoshizaki's analysis but not in Arndt and Roper's. The np data are inadequate to permit determination of the I = O phase parameters above 600 MeV. 27 references
Energy Technology Data Exchange (ETDEWEB)
Kees de Jager
2002-10-01
A review of data on the nucleon electro-weak form factors in the space-like region is presented. Recent results from experiments using polarized beams and either polarized targets or nucleon recoil polarimeters have yielded a significant improvement on the precision of the electromagnetic data obtained with the traditional Rosenbluth separation. An outlook is presented of planned experiments.
Time-reversal-invariance-violating nucleon-nucleon potential in the 1/N_c expansion
Samart, Daris; Schindler, Matthias R; Phillips, Daniel R
2016-01-01
We apply the large-$N_c$ expansion to the time-reversal-invariance-violating (TV) nucleon-nucleon potential. The operator structures contributing to next-to-next-to-leading order in the large-$N_c$ counting are constructed. For the TV and parity-violating case we find a single operator structure at leading order. The TV but parity-conserving potential contains two leading-order terms, which however are suppressed by 1/$N_c$ compared to the parity-violating potential. Comparison with phenomenological potentials, including the chiral EFT potential in the TV parity-violating case, leads to large-$N_c$ scaling relations for TV meson-nucleon and nucleon-nucleon couplings.
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_...
Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order
Epelbaum, E; Meißner, U -G
2014-01-01
We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362], [D.R. Entem, R. Machleidt, Phys. Rev. C68 (2003) 041001] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c_i and d_i determined from pion-nucleon scattering without any fine tuning. We discuss in detail t...
International Nuclear Information System (INIS)
Proton induced nuclear reactions at low proton energies are commonly used for production of radioactive isotopes which are important for many different applications. The production yield depends on excitation function features for the used nuclear reaction. In this work the excitation functions for more than 80 protons induced nuclear reactions were constructed using the ALICE-IPPE code which depends on the pre equilibrium model. Four groups of different isotopes were chosen to study the effect of the excess target neutrons on the threshold energy (Ethr), maximum reaction cross section (σmax) and the energy at maximum cross section (Emax). The selected groups were the natural isotopes of Ti, Cr, Fe and Ni. For the study of the effect of excess target protons on the same previous parameters, the excitation functions for the reactions on the isotones group 54Cr, 55Mn, 56Fe and 58Ni were performed at the same proton energy range. In order to understand the effect of the neutron to proton ratio on the previously mentioned parameters, proton reactions on the group of isobars 50Ti, 50V and 50Cr had been studied. In each case three protons induced reactions were undertaken, manly (p,n), (p,2n) and (p,3n). Each of the three previously mentioned parameters for each reaction were tabulated as a function of the excess number of nucleons and curve fit were constructed in order to get some phenomenological formulae for the behavior of these parameters
Non-singlet spin structure function in valon model
International Nuclear Information System (INIS)
We present a Next-to-leading order QCD calculation of non-singlet spin structure function g1NS(x,Q2), of the nucleon in the so-called the valon representation. The structure of the valon itself develops through the perturbative dressing of a valence quark in QCD, which is independent of the hosting hadron. The results of this calculations are in excellent agreement with the experimental data from HERMES collaborations for the entire measured range of x. It also provides an acceptable agreement with the older data from SMC, E143 and E155 experiments. We have further compared our results with those from AA, BB, GRSV, and DNS global fits.
Non-singlet spin structure function in valon model
Energy Technology Data Exchange (ETDEWEB)
Taghavi Shahri, Fatemeh [School of Particles and Accelerators,IPM, Institute for Studies in Theoretical Physics and Mathematics, P.O.Box 19395-5531, Tehran (Iran); Arash, Firooz [Department of Physics, Tafresh University, Tafresh (Iran)
2009-07-01
We present a Next-to-leading order QCD calculation of non-singlet spin structure function g{sub 1}{sup NS}(x,Q{sup 2}), of the nucleon in the so-called the valon representation. The structure of the valon itself develops through the perturbative dressing of a valence quark in QCD, which is independent of the hosting hadron. The results of this calculations are in excellent agreement with the experimental data from HERMES collaborations for the entire measured range of x. It also provides an acceptable agreement with the older data from SMC, E143 and E155 experiments. We have further compared our results with those from AA, BB, GRSV, and DNS global fits.
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.
International Nuclear Information System (INIS)
The problem of temperature dependence of nucleon mass is addressed by considering a retarded correlator of two currents with quantum numbers of a nucleon at finite temperature T π in the chiral limit. It is shown that at Euclidean momenta the leading one-loop corrections arise from direct interaction of thermal pions with the currents. A dispersive representation for the correlator shows that this interaction smears the nucleon pole over frequency interval with width ∼ T. This interaction does not change the exponential fall-off of the correlator in Euclidean space but gives an O(T2/Fπ2) contribution to the pre-exponential factor. 11 refs. (author)
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.
Structural Chemistry of Functional Materials
Institute of Scientific and Technical Information of China (English)
2011-01-01
@@ This innovative research group on structural chemistry of functional materials was approved by NSFC in 2005.Headed by Prof.HONG Maochun, the team consists of several young research scientists from the CAS Fujian Institute of Research on the Structures of Matter, including Profs CAO Rong, LU Canzhong, GUO Guocong, CHEN Zhongning, MAO Jianggao Mao and CHEN Ling.
Cottingham formula and nucleon polarisabilities
Energy Technology Data Exchange (ETDEWEB)
Gasser, J.; Leutwyler, H. [Universitaet Bern, Albert Einstein Center for Fundamental Physics, Institut fuer theoretische Physik, Bern (Switzerland); Hoferichter, M. [Universitaet Bern, Albert Einstein Center for Fundamental Physics, Institut fuer theoretische Physik, Bern (Switzerland); Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, ExtreMe Matter Institute EMMI, Darmstadt (Germany); University of Washington, Institute for Nuclear Theory, Seattle, WA (United States); Rusetsky, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Bonn (Germany)
2015-08-15
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections - provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon polarisabilities. We evaluate the sum rule for the difference between the electric polarisabilities of proton and neutron by means of the available parameterisations of the data and compare the result with experiment. (orig.)
Li, Qingfeng; Li, Zhuxia; Soff, Sven; Bleicher, Marcus; Stöcker, Horst
2006-01-01
Several observables of unbound nucleons which are to some extent sensitive to the medium modifications of nucleon-nucleon elastic cross sections in neutron-rich intermediate energy heavy ion collisions are investigated. The splitting effect of neutron and proton effective masses on cross sections is discussed. It is found that the transverse flow as a function of rapidity, the $Q_{zz}$ as a function of momentum, and the ratio of halfwidths of the transverse to that of longitudinal rapidity di...
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)
Studies on regge behaviour and spin-independent and spin-dependent structure functions
Jamil, Begum Umme
2010-01-01
Deep Inelastic Scattering (DIS) experiments have provided important information on the structure of hadrons and ultimately the structure of matter and on the nature of interactions between leptons and hadrons, since the discovery of partons. Various high energy deep inelastic interactions lead to different evolution equations from which we obtain various structure functions giving information about the partons i.e. quarks and gluons involved in different scattering processes. Actually structure function is a mathematical picture of the hadron structure in the high energy region. Understanding the behaviour of the structure functions of the nucleon at low-x, where x is the Bjorken variable, is interesting both theoretically and phenomenologically. Structure functions are important inputs in many high energy processes and also important for examination of perturbative quantum chromodynamics (PQCD), the underlying dynamics of quarks and gluons. In PQCD, for high-Q2, where Q2 is the four momentum transfer in a DI...
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.
Unitarity Corrections and Structure Functions
Gay-Ducati, M B
2002-01-01
We have studied the color dipole picture for the description of the deep inelastic process, mainly the structure functions which are driven directly by the gluon distribution. Estimates for those functions are obtained using the effective dipole cross section given by the Glauber-Mueller approach in QCD, encoding the corrections due to the unitarity effects associated with the saturation phenomenon. Frame invariance is verified in the calculations of the observables when analysing the experimental data.
Structure functions and parton distributions
Energy Technology Data Exchange (ETDEWEB)
Martin, A.D.; Stirling, W.J. [Univ. of Durham (United Kingdom); Roberts, R.G. [Rutherford Appleton Lab., Chilton, Didcot (United Kingdom)
1995-07-01
The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.
Nucleon form factors, generalized parton distributions and quark angular momentum
Energy Technology Data Exchange (ETDEWEB)
Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kroll, Peter [Bergische Univ., Wuppertal (Germany). Fachbereich Physik; Regensburg Univ. (Germany). Institut fuer Theoretische Physik
2013-02-15
We extract the individual contributions from u and d quarks to the Dirac and Pauli form factors of the proton, after a critical examination of the available measurements of electromagnetic nucleon form factors. From this data we determine generalized parton distributions for valence quarks, assuming a particular form for their functional dependence. The result allows us to study various aspects of nucleon structure in the valence region. In particular, we evaluate Ji's sum rule and estimate the total angular momentum carried by valence quarks at the scale {mu}=2 GeV to be J{sup u}{sub v}=0.230{sup +0.009}{sub -0.024} and J{sup d}{sub v}=-0.004{sup +0.010}{sub -0.016}.
Energy Technology Data Exchange (ETDEWEB)
Corradi, Lorenzo, E-mail: corradi@lnl.infn.it [INFN, Laboratori Nazionali di Legnaro, Viale dell’Universita’ 2 - 35020, Legnaro (Padova) - Italy (Italy)
2015-10-15
Excitation functions of one- and two-neutron transfer channels have been measured for the {sup 96}Zr+{sup 40}Ca and {sup 116}Sn+{sup 60}Ni systems at bombarding energies ranging from the Coulomb barrier to ∼25% below. Target-like recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental transfer probabilities have been compared, in absolute values and in slope, with semiclassical microscopic calculations which incorporate nucleon-nucleon pairing correlations. For the first time in a heavy ion collision, one was able to provide a consistent description of one and two neutron transfer reactions by incorporating, in the reaction mechanism, all known structure information of entrance and exit channels nuclei. In particular, there is no need to introduce any enhancement factor for the description of two neutron transfer, of course very important are the correlations induced by the pairing interaction.
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)
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
Proton structure functions at HERA
Stella, Bruno
2001-10-01
The electron-proton collider HERA, like an electron-mycroscope, explores the structure of the proton down to 10-16 cm and up to the situation of very high parton densities. The proton energy was upgraded from 820 to 920 GeV in the Fall of '98 and the luminosity has also substantially improved, with another factor of 3 upgrade expected to follow this year. Inclusive proton structure functions have been studied with incident e+ and e- of 27 GeV in the neutral (NC) and charged (CC) current interactions as functions of the squared four-momentum transfer, Q2, and of the fractional proton momentum carried by partons, x. The structure function F2, as well as the γ-Z0 interference term xF3, have been measured in a range of Q2 and 1/x that extends by orders of magnitude that reached by fixed target experiments. The DGLAP evolution equations [1] allow for a perturbative NLO QCD fit of the measured non-perturbative structure functions in the available kinematic range: αS and the gluon density at low x are fitted at the same time with good precision. The longitudinal structure function, FL, can be determined within the DGLAP formalism. With CC, the electroweak unification has been tested; at high x, a first flavor decomposition of the light quarks is achieved. The contribution to F2 of the charm quark has been measured and results to be relevant. Bounds on the radius of quarks and on compositeness are derived from the data at the highest Q2, 100
Next-to-leading-order constituent quark structure and hadronic structure functions
International Nuclear Information System (INIS)
We utilize the existing next-to-leading-order (NLO) formalism to calculate the partonic structure of a constituent quark. The structure of any hadron can be obtained thereafter using a convolution method. Such a procedure is used to generate the structure functions of protons and pions in NLO, neglecting certain corrections to ΛQCD. It is shown that while the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contribution coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the SU(2) symmetry breaking of the nucleon sea and the observed violation of the Gottfried sum rule. These effects are calculated. We obtained an excellent agreement with the experimental data in a wide range of x=[10-6,1] and Q2=[0.5,5000] GeV2 for the proton structure function. We have also calculated pion structure and compared it with the existing data. Again, the model calculations agree rather well with the data from experiment
Next-to-leading-order constituent quark structure and hadronic structure functions
Arash, Firooz; Khorramian, Ali N.
2003-04-01
We utilize the existing next-to-leading-order (NLO) formalism to calculate the partonic structure of a constituent quark. The structure of any hadron can be obtained thereafter using a convolution method. Such a procedure is used to generate the structure functions of protons and pions in NLO, neglecting certain corrections to ΛQCD. It is shown that while the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contribution coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the SU(2) symmetry breaking of the nucleon sea and the observed violation of the Gottfried sum rule. These effects are calculated. We obtained an excellent agreement with the experimental data in a wide range of x=[10-6,1] and Q2=[0.5,5000] GeV2 for the proton structure function. We have also calculated pion structure and compared it with the existing data. Again, the model calculations agree rather well with the data from experiment.
Tau lepton polarization in quasielastic neutrino-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Kuzmin, Konstantin S. [Joint Institute for Nuclear Research, RU-141980, Dubna, Moscow region (Russian Federation); Institute for Theoretical and Experimental Physics, RU-117218, Moscow (Russian Federation); Lyubushkin, Vladimir V. [Joint Institute for Nuclear Research, RU-141980, Dubna, Moscow region (Russian Federation); Physics Department, Irkutsk State University, RU-664003, Irkutsk (Russian Federation); Naumov, Vadim A. [Joint Institute for Nuclear Research, RU-141980, Dubna, Moscow region (Russian Federation); Dipartimento di Fisica, Universita degli Studi di Firenze and INFN Sezione di Firenze, I-50019, Sesto Fiorentino (Finland) (Italy)
2005-02-15
We derive structure functions for the quasielastic production of octet baryons in {nu}{sub {tau}}n and {nu}-bar {sub {tau}}p interactions and study the polarization of {tau} leptons produced in the {delta}Y=0 reactions. Possible impact of the charged second-class currents is investigated by adopting a simple phenomenological parametrization for the nonstandard scalar and tensor nucleon form factors. Our choice of the unknown parameters is made to satisfy the limits obtained in the (anti)neutrino scattering experiments and rigid restrictions derived from the nuclear structure studies.
High-x structure function of the virtually free neutron
Cosyn, Wim; Sargsian, Misak M.
2016-05-01
The pole extrapolation method is applied to the semi-inclusive inelastic electron scattering off the deuteron with tagged spectator protons to extract the high-x structure function of the neutron. This approach is based on the extrapolation of the measured cross sections at different momenta of the spectator proton to the nonphysical pole of the bound neutron in the deuteron. The advantage of the method is in the possibility of suppression of the nuclear effects in a maximally model-independent way. The neutron structure functions obtained in this way demonstrate a surprising x dependence at x ≥0.6 and 1.6 ≤Q2≤3.38 GeV2 , indicating a possible rise of the neutron-to-proton structure functions ratio. If the observed rise is valid in the true deep inelastic region then it 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.
Energy Technology Data Exchange (ETDEWEB)
Shahveh, Abolfazl [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of); Taghavi-Shahri, Fatemeh [School of Particles and Accelerators, Institute for Research in Fundamental, Sciences (IPM) P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Arash, Firooz, E-mail: farash@cic.aut.ac.i [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of)
2010-07-12
In the context of the so-called valon model, we calculate ({delta}g)/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of ({delta}g)/g in the measured kinematical region should not be interpreted as {delta}g being small. In fact, {delta}g itself at small x, and the first moment of the polarized gluon distribution in the nucleon, {Delta}g(Q{sup 2}), are large.
International Nuclear Information System (INIS)
In the context of the so-called valon model, we calculate (δg)/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of (δg)/g in the measured kinematical region should not be interpreted as δg being small. In fact, δg itself at small x, and the first moment of the polarized gluon distribution in the nucleon, Δg(Q2), are large.
Shahveh, Abolfazl; Taghavi-Shahri, Fatemeh; Arash, Firooz
2010-07-01
In the context of the so-called valon model, we calculate δg/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of δg/g in the measured kinematical region should not be interpreted as δg being small. In fact, δg itself at small x, and the first moment of the polarized gluon distribution in the nucleon, Δg (Q2), are large.
The nucleon-nucleon potential in the chromodielectric soliton model
Koepf, W.; Wilets, L.; Pepin, S.; Stancu, F.
The short and medium range parts of the nucleon-nucleon interaction are being studied in the framework of the chromodielectric soliton model. The model consists of current quarks, gluons in the abelian approximation, and a scalar sigma field which simulates the nonabelian interactions of the gluons and governs the medium through the dielectric function kappa(sigma). Absolute color confinement is effected by the vanishing of the dielectric in vacuum; this also removes the troublesome van der Waals problem. The authors distinguish between spatial confinement, which arises from the self energy of the quarks in medium (excluding MFA contributions), and color confinement which is effected through OGE in the MFA (including the corresponding self energy contributions). The static (adiabatic) energies are computed as a function of deformation (generalized bag separation) in a constrained MFA. Six quark molecular-type wave functions in all important space-spin-isospin-color configurations are included. The gluon propagator is solved in the deformed dielectric medium. The resultant Hamiltonian matrix is diagonalized. Dynamics are handled in the generator coordinate method, which leads to the Hill-Wheeler integral equation. In the present case, this yields a set of coupled equations corresponding to the various configurations. Although this can be approximated by a set of differential equations, they propose to solve the integral equations with some regularization scheme.
Factor XIII: Structure and Function.
Schroeder, Verena; Kohler, Hans P
2016-06-01
Over the last two decades, it became evident that factor XIII (FXIII) is not only a crucial determinant of clot characteristics but also has potentially important functions in many various fields such as bone biology, immunity, and adipogenesis. In this review, we aim to summarize the latest findings regarding structure and function of FXIII. In regard to FXIII structure, much progress has been made recently to understand how its subunits are held together. In the A subunit, the activation peptide has a crucial role in the formation of FXIII-A2 dimers. In the B subunit, Sushi domains that are involved in binding to the A subunit and in B2 dimer formation have been identified. In regard to FXIII function, interactions with immune cells and the complement system have been described. A novel function of FXIII-A in adipogenesis has been suggested. The role of FXIII-A in osteoblast differentiation has been further investigated; however, a novel double knockout mouse deficient in both FXIII-A and transglutaminase 2 showed normal bone formation. Thus, more research, in particular, into the cellular functions of FXIII-A is still required. PMID:27019464
Accardi, Alberto
2016-01-01
I review recent progress in the extraction of unpolarized parton distributions in the proton and in nuclei from a unified point of view that highlights how the interplay between high energy particle physics and lower energy nuclear physics can be of mutual benefit to either field. Areas of overlap range from the search for physics beyond the standard model at the LHC, to the study of the non perturbative structure of nucleons and the emergence of nuclei from quark and gluon degrees of freedom, to the interaction of colored probes in a cold nuclear medium.
Exact symmetries and the role of the pion cloud in deep-inelastic electron-nucleon scattering
International Nuclear Information System (INIS)
A careful analysis of exact symmetries, such as the charge conjugation symmetry and the electromagnetic and baryon current conservation, shows that exactly two nontrivial Feynman diagrams contribute to deep-inelastic inclusive pion electroproduction from the nucleon to O(gπNN2). The same analysis reveals certain relationships between the two graphs. The two graphs are expressed as convolutions of the pion [gπ(y)] and the nucleon [gN(y)] smearing functions and their respective deep-inelastic structure functions. The nucleon smearing functions are evaluated in three models of the nucleon off-shell dependence of the πNN vertex function and they turn out to have remarkably similar shapes. It is shown that this universality of gN(y) persists in a wide class of models. Such universal gN(y) peaks at y0=1-mπ/MN=0.85 and allows a simple parton model interpretation. Furthermore, the normalized smearing functions approximately satisfy the Berger-Coester-Wiringa-Thomas ansatz gπ(y)=gN(1-y) for two of the three models examined. Strong constraints on the nucleon off-shell dependence of the πNN vertex function [gπNN(pN2)] are obtained using the observed Gottfried sum rule violation as empirical input
Structure and Function of Glucansucrases
Dijkstra, B. W.; Vujičić-Žagar, A.
2008-03-01
Glucansucrases are relatively large (~160 kDa) extracellular enzymes produced by lactic acid bacteria. Using sucrose as a substrate they synthesize high molecular mass glucose polymers, called α-glucans, which allow the bacteria to adhere to surfaces and create a biofilm. The glucan polymers are of importance for the food and dairy industry as thickening and jellying agents. An overview is given of the current insights into the structure and functioning of these and related enzymes.
Haider, H; Athar, M Sajjad; Singh, S K; Simo, I Ruiz
2016-01-01
We have studied nuclear structure functions $F_{1A}(x,Q^2)$ and $F_{2A}(x,Q^2)$ for electromagnetic and weak processes in the region of $1 GeV^2 < Q^2 <8 GeV^2$. The nuclear medium effects arising due to Fermi motion, binding energy, nucleon correlations, mesonic contributions and shadowing effects are taken into account using a many body field theoretical approach. The calculations are performed in a local density approximation using a relativistic nucleon spectral function. The results are compared with the available experimental data. Implications of nuclear medium effects on the validity of Callan-Gross relation are also discussed.
Two-nucleon transfer reactions uphold supersymmetry in atomic nuclei
Barea, J.; Bijker, R.; Frank, A.
2004-01-01
The spectroscopic strengths of two-nucleon transfer reactions constitute a stringent test for two-nucleon correlations in the nuclear wave functions. A comparison between the recently measured 198Hg(d,alpha)196Au reaction and the predictions from the nuclear quartet supersymmetry lends further support to the validity of supersymmetry in nuclear physics.
A study of nuclear effect in $F_3$ structure function in the deep inelastic $\
Athar, M Sajjad; Singh, S K; Vacas, M J Vicente
2009-01-01
We study nuclear effect in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by taking into account Fermi motion, binding, target mass correction, shadowing and anti-shadowing corrections. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. Results for $F^A_3(x)$ have been compared with the results reported at NuTeV and also with some of the older experiments reported in the literature.
Measurement of the neutron spin structure function---Test of the Bjorken sum rule
International Nuclear Information System (INIS)
As experiment to measure the neutron spin-dependent structure function g1n (x) over a range in x from 0.04 to 0.7 and with Q2 > 1 (GeV/c)2 is presented. The experiment consists of scattering a longitudinally polarized electron beam from the Stanford Linear Accelerator off a polarized 3He target and detecting scattered electrons in two magnetic spectrometers. The experiment will provide a critical test of the Bjorken sum rule and valuable information in understanding the nucleon spin structure and the violation of the Ellis-Jaffe sum rule. 3 figs., 1 tab
Tissue Factor Structure and Function
Directory of Open Access Journals (Sweden)
Saulius Butenas
2012-01-01
Full Text Available Tissue factor (TF is an integral membrane protein that is essential to life. It is a component of the factor VIIa-TF complex enzyme and plays a primary role in both normal hemostasis and thrombosis. With a vascular injury, TF becomes exposed to blood and binds plasma factor VIIa, and the resulting complex initiates a series of enzymatic reactions leading to clot formation and vascular sealing. Many cells, both healthy, and tumor cells, produce detectable amounts of TF, especially when they are stimulated by various agents. Despite the relative simplicity and small size of TF, there are numerous contradictory reports about the synthesis and presentation of TF on blood cells and circulation in normal blood either on microparticles or as a soluble protein. Another subject of controversy is related to the structure/function of TF. It has been almost commonly accepted that cell-surface-associated TF has low (if any activity, that is, is “encrypted” and requires specific conditions/reagents to become active, that is, “decrypted.” However there is a lack of agreement related to the mechanism and processes leading to alterations in TF function. In this paper TF structure, presentation, and function, and controversies concerning these features are discussed.
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.
Structure and function of aggrecan
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Aggrecan is the major proteoglycan in the articular cartilage. This molecule is important in the proper functioning of articular cartilage because it provides a hydrated gel structure (via its interaction with hyaluronan and link protein) that endows the cartilage with load-bearing properties. It is also crucial in chondroskeletal morphogenesis during development. Aggrecan is a multimodular molecule expressed by chondrocytes. Its core protein is composed of three globular domains (Gl, G2, and G3) and a large extended region (CS) between G2 and G3 for glycosaminoglycan chain attachment. G1 comprises the amino terminus of the core protein. This domain has the same structural motif as link protein. Functionally, the G1 domain interacts with hyaluronan acid and link protein, forming stable ternary complexes in the extracellular matrix.G2 is homologous to the tandem repeats of G1 and of link protein and is involved in product processing. G3makes up the carboxyl terminus of the core protein. It enhances glycosaminoglycan modification and product secretion. Aggrecan plays an important role in mediating chondrocyte-chondrocyte and chondrocyte-matrix interactions through its ability to bind hyaluronan.
Deep Inelastic Scattering from A=3 Nuclei and the Neutron Structure Function
Energy Technology Data Exchange (ETDEWEB)
I. Afnan; F. Bissey; J. Gomez; A. Katramatou; S. Liuti; W. Melnitchouk; G. Petratos; A.W. Thomas
2003-03-01
We present a comprehensive analysis of deep inelastic scattering from {sup 3}He and {sup 3}H, focusing in particular on the extraction of the free neutron structure function, F{sup n}{sub 2}. Nuclear corrections are shown to cancel to within 1-2% for the isospin-weighted ratio of {sup 3}He to {sup 3}H structure functions, which leads to more than an order of magnitude improvement in the current uncertainty on the neutron to proton ratio F{sup 2n}{sub 2}/F{sup p}{sub 2} at large x. Theoretical uncertainties originating tom the nuclear wave function, including possible non-nucleonic components, are evaluated. Measurement of the {sup 3}He and {sup 3}H structure functions will, in addition, determine the magnitude of the EMC effect in all A [lte] 3 nuclei.
Nucleon-Nucleon Parity Violation Experiments
Van Oers, W T H
1999-01-01
Measurements of parity-violating longitudinal analyzing powers Az (normalized asymmetries) in polarized proton-proton scattering and in polarized neutron capture on the proton (n+p -> d+gamma) provide a unique window on the interplay between the weak and strong interactions between and within hadrons. Several new proton-proton parity violation experiments are presently either being performed or are being prepared for execution in the near future: at TRIUMF at 221 MeV and 450 MeV and at COSY (Forschungszentrum Jülich) in the multi-GeV range. A new measurement of the parity-violating gamma ray asymmetry with a ten-fold improvement in the accuracy over previous measurements is being developed at LANSCE. These experiments are intended to provide stringent constraints on the set of six effective weak meson-nucleon coupling constants, which characterize the weak interaction between hadrons in the energy domain where meson exchange models provide an appropriate description. The 221 MeV pp experiment is unique in th...
International Nuclear Information System (INIS)
Structure of energy spectra and backbending phenomena of the isotope string of Hf with mass number between 162 and 170 have been investigated. Extend of SU(3)-limits of interacting boson model to allow a boson to break to form a quasiparticle pair, which can occupy h11/2 and i13/2 orbitals. The calculated energy levels, intensity of the electromagnetic transitions, including the ground state, β and γ band are in satisfactory agreement with observed values for the whole string of Hf isotopes. Backbending of the moment inertia of the yrast and β bands can be reproduced reasonably. Recently, very high spin states up to J=40 and a double backbending have been observed in some nuclei in rare-earth region. This phenomena might hopefully be interpreted by considering two or more bosons to break to form more quasiparticle pairs and make more bands crossing to form the double backbending
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.
The nucleon-nucleon potential beyond the static approximation
Mondejar, Jorge; Soto, Joan
2006-01-01
We point out that, due to the use of static nucleon propagators in Heavy Baryon Chiral Perturbation Theory, the current calculations of the nucleon-nucleon potential miss certain contributions starting at two loops. These contributions give rise to contact interactions, which are both parametrically and numerically more important than the so called NNLO potentials. They show a peculiar dependence on the light quark masses, which should be taken into account when performing chiral extrapolatio...
The nucleon-nucleon potential beyond the static approximation
Mondejar, J; Mondejar, Jorge; Soto, Joan
2006-01-01
We point out that, due to the use of static nucleon propagators in Heavy Baryon Chiral Perturbation Theory, the current calculations of the nucleon-nucleon potential miss certain contributions starting at two loops. These contributions give rise to contact interactions, which are both parametrically and numerically more important than the so called NNLO potentials. They show a peculiar dependence on the light quark masses, which should be taken into account when performing chiral extrapolations of lattice data.
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.
Structure Functions in Semihadronic Tau Decays
Colangelo, Gilberto; Finkemeier, Markus; Mirkes, Erwin; Urech, Res
1996-01-01
We review a variety of topics related to hadronic structure functions in exclusive semihadronic tau decays. We introduce the concept of structure functions and summarize the most important concepts. We then calculate the decay $\\tau \\to 3 \\pi \
Technical data on nucleonic gauges
International Nuclear Information System (INIS)
This nucleonic gauge manual and directory provides a reference database of nucleonic control systems available to potential users in the fields of exploration, exploitation and processing of natural resources and in the manufacturing industries. It starts with background information an the general principals of nucleonic gauges, followed by portable nuclear analysis systems (PNAS), computer tomography, cost-benefit on NCS (Nucleonic Control Systems) applications and trends and transfer of NCS technology. It continues with radiation protection and safety, discusses nucleonic gauges with low radioactivity sources and ends with typical models of nucleonic gauges. The basic principles of the most popular techniques are reviewed and reference data links to suppliers are provided. Information sheets on many typical commercial devices are also included. It will help end-users to select the most suitable alternative to solve a particular problem or to measure a certain parameter in a specific process
Microscopic Calculation of the Inclusive Electron Scattering Structure Function in 16O
Mihaila, Bogdan; Heisenberg, Jochen H.
2000-02-01
We calculate the charge form factor and the longitudinal structure function for 16O and compare with the available experimental data, up to a momentum transfer of 4 fm-1. The ground-state correlations are generated using the coupled-cluster [ exp\\(S\\)] method, together with the realistic v18 NN interaction and the Urbana IX three-nucleon interaction. Center-of-mass corrections are dealt with by adding a center-of-mass Hamiltonian to the usual internal Hamiltonian, and by means of a many-body expansion for the computation of the observables measured in the center-of-mass system.
Microscopic calculation of the inclusive electron scattering structure function in O-16
Mihaila, B; Mihaila, Bogdan; Heisenberg, Jochen
2000-01-01
We calculate the charge form factor and the longitudinal structure function for $^{16}$O and compare with the available experimental data, up to a momentum transfer of 4 fm$^{-1}$. The ground state correlations are generated using the coupled cluster [exp(S}] method, together with the realistic v-18 NN interaction and the Urbana IX three-nucleon interaction. Center-of-mass corrections are dealt with by adding a center-of-mass Hamiltonian to the usual internal Hamiltonian, and by means of a many-body expansion for the computation of the observables measured in the center-of-mass system.
Target mass corrections for spin-dependent structure functions in collinear factorization
Accardi, A
2008-01-01
We derive target mass corrections (TMC) for the spin-dependent nucleon structure function g1 and polarization asymmetry A1 in collinear factorization at leading twist. The TMCs are found to be significant for g1 at large xB, even at relatively high Q^2 values, but largely cancel in A1. A comparison of TMCs obtained from collinear factorization and from the operator product expansion shows that at low Q^2 the corrections drive the proton A1 in opposite directions.
Nuclear longitudinal structure function in eA processes at the LHeC
Boroun, G R; Heidari, S
2016-01-01
The nucleon and nuclear longitudinal structure functions are determined by the Kharzeev-Levin-Nardin (KLN) model of the low $x$ gluon distribution. The behavior of the gluon distribution ratio $R_{g}=\\frac{G^{A}}{AG^{p}}$ and the ratio $R_{L}^{total}=\\frac{F_{L}^{A-total}}{AF_{L}^{p-total}}$ in this processes are found. The heavy longitudinal structure function ratios $R_{L}^{H}=\\frac{F_{L}^{H(A)}}{AF_{L}^{H(p)}}$ in eA processes at the LHeC region are discussed. Heavy contributions to the total longitudinal structure function ratio $R^{H}_{L}$ are considerable and should not be neglected especially at smaller $x$ of the LHeC project. In the KLN model the new geometrical scaling for transition from the linear to nonlinear regions in accordance with the LHeC processes is used, whose results intensively depended on the heavy quarks mass effect.
Structure Function Estimated From Histological Tissue Sections.
Han, Aiguo; O'Brien, William D
2016-09-01
Ultrasonic scattering is determined by not only the properties of individual scatterers but also the correlation among scatterer positions. The role of scatterer spatial correlation is significant for dense medium, but has not been fully understood. The effect of scatterer spatial correlation may be modeled by the structure function as a frequency-dependent factor in the backscatter coefficient (BSC) expression. The structure function has been previously estimated from the BSC data. The aim of this study is to estimate the structure function from histology to test if the acoustically estimated structure function is indeed caused by the scatterer spatial distribution. Hematoxylin and eosin stained histological sections from dense cell pellet biophantoms were digitized. The scatterer positions were determined manually from the histological images. The structure function was calculated from the extracted scatterer positions. The structure function obtained from histology showed reasonable agreement in the shape but not in the amplitude, compared with the structure function previously estimated from the backscattered data. Fitting a polydisperse structure function model to the histologically estimated structure function yielded relatively accurate cell radius estimates ([Formula: see text]). Furthermore, two types of mouse tumors that have similar cell size and shape but distinct cell spatial distributions were studied, where the backscattered data were shown to be related to the cell spatial distribution through the structure function estimated from histology. In conclusion, the agreement between acoustically estimated and histologically estimated structure functions suggests that the acoustically estimated structure function is related to the scatterer spatial distribution.
Modarres, M.; Younesizadeh, Y.
2012-05-01
In this work, the two-nucleon spectral functions (TNSFs) are defined in terms of the state- and the density-dependent correlation functions in the framework of the lowest-order constrained variational (LOCV) method to calculate the TNSF of the 16O nucleus in the 16O(e,e'NN)14C reaction. The Reid soft-core (Reid68) and the Av18 potentials are used as the internucleon interactions. Since, the short-range correlation effects are imposed on the wave functions for the individual channels (e.g., the 1S0 and 3PJ channels); therefore, the defect wave functions are obtained for various channels such that the high relative momenta (p>4fm-1) are ignored. The resulting TNSFs for the 16O nucleus are compared with those of the dressed random phase approximation (DRPA) calculations of Geurts and the experimental predictions, especially those of Onderwater , (NIKHEF group), where reasonable agreement is found. It is shown that the optimized state-dependent defect wave functions have substantial effects on the TNSF and it is not justified to use the simplified parametrized two-body correlation functions in all of the channels. In agreement with the experimental data of Onderwater , the knockout of a 1S0 pair proton dominates the above reaction cross section. Finally, it is demonstrated that the 0+ and 2+ peaks, which are expected to be observed in the above reaction cross section, are moved to the lower momenta of out-going protons when the state-dependent correlation functions are imposed.
Spectral asymmetries in nucleon sum rules at finite density
Furnstahl, R. J.
1993-01-01
Apparent inconsistencies between different formulations of nucleon sum rules at finite density are resolved through a proper accounting of asymmetries in the spectral functions between positive- and negative-energy states.
Few-nucleon systems with state-of-the-art chiral nucleon-nucleon forces
Binder, S; Epelbaum, E; Furnstahl, R J; Golak, J; Hebeler, K; Kamada, H; Krebs, H; Langhammer, J; Liebig, S; Maris, P; Meißner, U -G; Minossi, D; Nogga, A; Potter, H; Roth, R; Skibinski, R; Topolnicki, K; Vary, J P; Witala, H
2015-01-01
We apply improved nucleon-nucleon potentials up to fifth order in chiral effective field theory, along with a new analysis of the theoretical truncation errors, to study nucleon-deuteron (Nd) scattering and selected low-energy observables in 3H, 4He, and 6Li. Calculations beyond second order differ from experiment well outside the range of quantified uncertainties, providing truly unambiguous evidence for missing three-nucleon forces within the employed framework. The sizes of the required three-nucleon force contributions agree well with expectations based on Weinberg's power counting. We identify the energy range in elastic Nd scattering best suited to study three-nucleon force effects and estimate the achievable accuracy of theoretical predictions for various observables.
Soft nanotechnology: "structure" vs. "function".
Whitesides, George M; Lipomi, Darren J
2009-01-01
This paper offers a perspective on "soft nanotechnology"; that is, the branch of nanotechnology concerned with the synthesis and properties of organic and organometallic nanostructures, and with nanofabrication using techniques in which soft components play key roles. It begins with a brief history of soft nanotechnology. This history has followed a path involving a gradual shift from the promise of revolutionary electronics, nanorobotics, and other futuristic concepts, to the realization of evolutionary improvements in the technology for current challenges in information technology, medicine, and sustainability. Soft nanoscience is an area that is occupied principally by chemists, and is in many ways indistinguishable from "nanochemistry". The paper identifies the natural tendency of its practitioners--exemplified by the speakers at this Faraday Discussion--to focus on synthesis and structure, rather than on function and application, of nanostructures. Soft nanotechnology has the potential to apply to a wide variety of large-scale applied (information technology, healthcare cost reduction, sustainability, energy) and fundamental (molecular biochemistry, cell biology, charge transport in organic matter) problems.
Renormalization of EFT for nucleon-nucleon scattering
Yang, J. -F.
2004-01-01
The renormalization of EFT for nucleon-nucleon scattering in nonperturbative regimes is investigated in a compact parametrization of the $T$-matrix. The key difference between perturbative and nonperturbative renormalization is clarified. The underlying theory perspective and the 'fixing' of the prescriptions for the $T$-matrix from physical boundary conditions are stressed.
Wang, D; Subedi, R; Deng, X; Ahmed, Z; Allada, K; Aniol, K A; Armstrong, D S; Arrington, J; Bellini, V; Beminiwattha, R; Benesch, J; Benmokhtar, F; Camsonne, A; Canan, M; Cates, G D; Chen, J -P; Chudakov, E; Cisbani, E; Dalton, M M; de Jager, C W; De Leo, R; Deconinck, W; Deur, A; Dutta, C; Fassi, L El; Flay, D; Franklin, G B; Friend, M; Frullani, S; Garibaldi, F; Giusa, A; Glamazdin, A; Golge, S; Grimm, K; Hafidi, K; Hansen, O; Higinbotham, D W; Holmes, R; Holmstrom, T; Holt, R J; Huang, J; Hyde, C E; Jen, C M; Jones, D; Kang, H; King, P; Kowalski, S; Kumar, K S; Lee, J H; LeRose, J J; Liyanage, N; Long, E; McNulty, D; Margaziotis, D J; Meddi, F; Meekins, D G; Mercado, L; Meziani, Z -E; Michaels, R; Mihovilovic, M; Muangma, N; Myers, K E; Nanda, S; Narayan, A; Nelyubin, V; Nuruzzaman,; Oh, Y; Parno, D; Paschke, K D; Phillips, S K; Qian, X; Qiang, Y; Quinn, B; Rakhman, A; Reimer, P E; Rider, K; Riordan, S; Roche, J; Rubin, J; Russo, G; Saenboonruang, K; Saha, A; Sawatzky, B; Shahinyan, A; Silwal, R; Sirca, S; Souder, P A; Suleiman, R; Sulkosky, V; Sutera, C M; Tobias, W A; Waidyawansa, B; Wojtsekhowski, B; Ye, L; Zhao, B; Zheng, X
2013-01-01
We report on parity-violating asymmetries in the nucleon resonance region measured using $5 - 6$ GeV longitudinally polarized electrons scattering off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the $\\Delta(1232)$, and provide a verification of quark-hadron duality in the nucleon electroweak $\\gamma Z$ interference structure functions at the 10-15% level. The results are of particular interest to models relevant for calculating the $\\gamma Z$ box-diagram corrections to elastic parity-violating electron scattering measurements.
Estimates of the Nucleon Tensor Charge
Gamberg, L P; Gamberg, Leonard; Goldstein, Gary R.
2001-01-01
Like the axial vector charges, defined from the forward nucleon matrix element of the axial vector current on the light cone, the nucleon tensor charge, defined from the corresponding matrix element of the tensor current, is essential for characterizing the momentum and spin structure of the nucleon. Because there must be a helicity flip of the struck quark in order to probe the transverse spin polarization of the nucleon, the transversity distribution (and thus the tensor charge) decouples at leading twist in deep inelastic scattering, although no such suppression appears in Drell-Yan processes. This makes the tensor charge difficult to measure and its non-conservation makes its prediction model dependent. We present a different approach. Exploiting an approximate SU(6)xO(3) symmetric mass degeneracy of the light axial vector mesons (a1(1260), b1(1235) and h1(1170)) and using pole dominance, we calculate the tensor charge. The result is simple in form and depends on the decay constants of the axial vector me...
Dimensional versus cut-off renormalization and the nucleon-nucleon interaction
Ghosh, A; Talukdar, B; Ghosh, Angsula; Adhikari, Sadhan K.
1998-01-01
The role of dimensional regularization is discussed and compared with that of cut-off regularization in some quantum mechanical problems with ultraviolet divergence in two and three dimensions with special emphasis on the nucleon-nucleon interaction. Both types of renormalizations are performed for attractive divergent one- and two-term separable potentials, a divergent tensor potential, and the sum of a delta function and its derivatives. We allow energy-dependent couplings, and determine the form that these couplings should take if equivalence between the two regularization schemes is to be enforced. We also perform renormalization of an attractive separable potential superposed on an analytic divergent potential.
Dimensional versus cut-off renormalization and the nucleon-nucleon interaction
Ghosh, Angsula; Adhikari, Sadhan K.; Talukdar, B.
1998-10-01
The role of dimensional regularization is discussed and compared with that of cut-off regularization in some quantum mechanical problems with ultraviolet divergence in two and three dimensions with special emphasis on the nucleon-nucleon interaction. Both types of renormalizations are performed for attractive divergent one- and two-term separable potentials, a divergent tensor potential, and the sum of a delta function and its derivatives. We allow energy-dependent couplings, and determine the form that these couplings should take if equivalence between the two regularization schemes is to be enforced. We also perform renormalization of an attractive separable potential superposed on an analytic divergent potential.
Three dimensional imaging of the nucleon --- TMD (theory and phenomenology)
Liang, Zuo-tang
2015-01-01
This is intend to provide an overview of the theoretical and phenomenological parts of the TMD (Transverse Momentum Dependent parton distribution and fragmentation functions) studies. By comparing with the theoretical framework that we have for the inclusive deep inelastic lepton-nucleon scattering and the one-dimensional imaging of the nucleon, I try to outline what we need to do in order to construct a comprehensive theoretical framework for semi-inclusive reactions and the three dimensional imaging of the nucleon. After that, I try to give an overview of what we have already achieved and make an outlook for the future.
Flavor Decomposition of the Nucleon
Melnitchouk, W.
1999-01-01
I review some recent developments in the study of quark flavor distributions in the nucleon, including (i) valence quark distributions and the quark-hadron duality prediction for the x -> 1 d/u ratio (ii) sea quark asymmetries and electromagnetic form factors (iii) strange quarks in the nucleon.
Three pion nucleon coupling constants
Ruiz Arriola, E.; Amaro, J. E.; Navarro Pérez, R.
2016-08-01
There exist four pion nucleon coupling constants, fπ0pp, ‑ fπ0nn, fπ+pn/2 and fπ‑np/2 which coincide when up and down quark masses are identical and the electron charge is zero. While there is no reason why the pion-nucleon-nucleon coupling constants should be identical in the real world, one expects that the small differences might be pinned down from a sufficiently large number of independent and mutually consistent data. Our discussion provides a rationale for our recent determination fp2 = 0.0759(4),f 02 = 0.079(1),f c2 = 0.0763(6), based on a partial wave analysis of the 3σ self-consistent nucleon-nucleon Granada-2013 database comprising 6713 published data in the period 1950-2013.
Three pion nucleon coupling constants
Arriola, E Ruiz; Perez, R Navarro
2016-01-01
There exist four pion nucleon coupling constants, $f_{\\pi^0, pp}$, $-f_{\\pi^0, nn}$, $f_{\\pi^+, pn} /\\sqrt{2}$ and $ f_{\\pi^-, np} /\\sqrt{2}$ which coincide when up and down quark masses are identical and the electron charge is zero. While there is no reason why the pion-nucleon-nucleon coupling constants should be identical in the real world, one expects that the small differences might be pinned down from a sufficiently large number of independent and mutually consistent data. Our discussion provides a rationale for our recent determination $$f_p^2 = 0.0759(4) \\, , \\quad f_{0}^2 = 0.079(1) \\,, \\quad f_{c}^2 = 0.0763(6) \\, , $$ based on a partial wave analysis of the $3\\sigma$ self-consistent nucleon-nucleon Granada-2013 database comprising 6713 published data in the period 1950-2013.
Flu BM2 structure and function
Cross, Timothy A
2009-01-01
Flu viruses package essential functions into a small integral membrane protein known as M2. Such small membrane proteins represent major challenges for structural biology. A new study presented in this issue details the structure and functions of the influenza B M2 protein through the use of functional domain–specific solution NMR spectroscopy.
Nucleon-pair approximation to the nuclear shell model
Energy Technology Data Exchange (ETDEWEB)
Zhao, Y.M., E-mail: ymzhao@sjtu.edu.cn [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Arima, A. [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Musashi Gakuen, 1-26-1 Toyotamakami Nerima-ku, Tokyo 176-8533 (Japan)
2014-12-01
Atomic nuclei are complex systems of nucleons–protons and neutrons. Nucleons interact with each other via an attractive and short-range force. This feature of the interaction leads to a pattern of dominantly monopole and quadrupole correlations between like particles (i.e., proton–proton and neutron–neutron correlations) in low-lying states of atomic nuclei. As a consequence, among dozens or even hundreds of possible types of nucleon pairs, very few nucleon pairs such as proton and neutron pairs with spin zero, two (in some cases spin four), and occasionally isoscalar spin-aligned proton–neutron pairs, play important roles in low-energy nuclear structure. The nucleon-pair approximation therefore provides us with an efficient truncation scheme of the full shell model configurations which are otherwise too large to handle for medium and heavy nuclei in foreseeable future. Furthermore, the nucleon-pair approximation leads to simple pictures in physics, as the dimension of nucleon-pair subspace is always small. The present paper aims at a sound review of its history, formulation, validity, applications, as well as its link to previous approaches, with the focus on the new developments in the last two decades. The applicability of the nucleon-pair approximation and numerical calculations of low-lying states for realistic atomic nuclei are demonstrated with examples. Applications of pair approximations to other problems are also discussed.
Nucleon Form Factors - A Jefferson Lab Perspective
Arrington, John; Perdrisat, Charles F
2011-01-01
The charge and magnetization distributions of the proton and neutron are encoded in their elastic electromagnetic form factors, which can be measured in elastic electron--nucleon scattering. By measuring the form factors, we probe the spatial distribution of the proton charge and magnetization, providing the most direct connection to the spatial distribution of quarks inside the proton. For decades, the form factors were probed through measurements of unpolarized elastic electron scattering, but by the 1980s, progress slowed dramatically due to the intrinsic limitations of the unpolarized measurements. Early measurements at several laboratories demonstrated the feasibility and power of measurements using polarization degrees of freedom to probe the spatial structure of the nucleon. A program of polarization measurements at Jefferson Lab led to a renaissance in the field of study, and significant new insight into the structure of matter.
Nucleon Electromagnetic Form Factors
Energy Technology Data Exchange (ETDEWEB)
Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi
2007-10-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.
Spin dependent structure function g1 of the deuteron and the proton. Doctoral thesis
Energy Technology Data Exchange (ETDEWEB)
Klostermann, L.
1995-08-01
This thesis presents a study on the spin structure of the nucleon, via deep inelastic scattering (DIS) of polarized muons on polarized 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 can 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 d) 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. The SMC results presented in this thesis are based on data taken in 1992 using a polarized deuterium target and polarized muons with an incident energy of 100 GeV, and 1993 data with a proton target and an incident muon energy of 190 GeV. Using all available data, the fundamental Bjorken sum rule has now been verified at the one standard deviation level to within 16% of its theoretical value.
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).
Dense nucleonic matter and the renormalization group
Drews, Matthias; Klein, Bertram; Weise, Wolfram
2013-01-01
Fluctuations are included in a chiral nucleon-meson model within the framework of the functional renormalization group. The model, with parameters fitted to reproduce the nuclear liquid-gas phase transition, is used to study the phase diagram of QCD. We find good agreement with results from chiral effective field theory. Moreover, the results show a separation of the chemical freeze-out line and chiral symmetry restoration at large baryon chemical potentials.
Dense nucleonic matter and the renormalization group
Directory of Open Access Journals (Sweden)
Drews Matthias
2014-03-01
Full Text Available Fluctuations are included in a chiral nucleon-meson model within the framework of the functional renormalization group. The model, with parameters fitted to reproduce the nuclear liquid-gas phase transition, is used to study the phase diagram of QCD. We find good agreement with results from chiral effective field theory. Moreover, the results show a separation of the chemical freeze-out line and chiral symmetry restoration at large baryon chemical potentials.
The nucleon in a periodic magnetic field
Agadjanov, Andria; Rusetsky, Akaki
2016-01-01
The energy shift of a nucleon in a static periodic magnetic field is evaluated at second order in the external field strength in perturbation theory. It is shown that the measurement of this energy shift on the lattice allows one to determine the unknown subtraction function in the forward doubly-virtual Compton scattering amplitude. The limits of applicability of the obtained formula for the energy shift are discussed.
Asymmetries of quark sea in nucleon
Dahiya Harleen
2014-01-01
The effects of “quark sea” in determining the flavor structure of the octet baryons have been investigated in the chiral constituent quark model. The chiral constituent quark model is able to qualitatively generate the requisite amount of quark sea and is also known to provide a satisfactory explanation of the proton spin and related issues in the nonperturbative regime. The phenomenological implications of the quark sea asymmetries in the nucleon have been investigated to understand the impo...
Nuclear effects in the structure functions
Indian Academy of Sciences (India)
E Marco; E Oset; S K Singh
2003-11-01
By using a relativistic framework and accurate nuclear spectral function the structure functions 2 and 3 of deep inelastic charged lepton and neutrino scattering are calculated in nuclei and results are presented.
Volume Dependence of the Axial Charge of the Nucleon
Hall, N. L.; Thomas, A. W.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia); Zanotti, J. M.
2012-01-01
It is shown that the strong volume-dependence of the axial charge of the nucleon seen in lattice QCD calculations can be understood quantitatively in terms of the pion-induced interactions between neighbouring nucleons. The associated wave function renormalization leads to an increased suppression of the axial charge as the strength of the interaction increases, either because of a decrease in lattice size or in pion mass.
Progress in the Calculation of Nucleon Transition form Factors
Eichmann, Gernot
2016-10-01
We give a brief account of the Dyson-Schwinger and Faddeev-equation approach and its application to nucleon resonances and their transition form factors. We compare the three-body with the quark-diquark approach and present a quark-diquark calculation for the low-lying nucleon resonances including scalar, axialvector, pseudoscalar and vector diquarks. We also discuss the timelike structure of transition form factors and highlight the advantages of form factors over helicity amplitudes.
Progress in the calculation of nucleon transition form factors
Eichmann, Gernot
2016-01-01
We give a brief account of the Dyson-Schwinger and Faddeev-equation approach and its application to nucleon resonances and their transition form factors. We compare the three-body with the quark-diquark approach and present a quark-diquark calculation for the low-lying nucleon resonances including scalar, axialvector, pseudoscalar and vector diquarks. We also discuss the timelike structure of transition form factors and highlight the advantages of form factors over helicity amplitudes.
Quasi-coherent state of pions in the nucleon
Morishita, M; Morishita, Masanori; Arima, Masaki
2003-01-01
Making use of the quasi-coherent state developed by Eriksson et al., we can find a nucleon solution accompanied by the pion field with trivial topology. We compare our approach with other related works, and examine a coherent state description of pions in the baryon structure. Our solution suggests a kind of nucleon resonance due to the topological change of pion field without the usual quark excitation.
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.
Probing short-range nucleon-nucleon interactions with an electron-ion collider
Miller, Gerald A.; Sievert, Matthew D.; Venugopalan, Raju
2016-04-01
We derive the cross section for exclusive vector meson production in high-energy deeply inelastic scattering off a deuteron target that disintegrates into a proton and a neutron carrying large relative momentum in the final state. This cross section can be expressed in terms of a novel gluon transition generalized parton distribution (T-GPD); the hard scale in the final state makes the T-GPD sensitive to the short-distance nucleon-nucleon interaction. We perform a toy model computation of this process in a perturbative framework and discuss the time scales that allow the separation of initial- and final-state dynamics in the T-GPD. We outline the more general computation based on the factorization suggested by the toy computation: In particular, we discuss the relative role of "pointlike" and "geometric" Fock configurations that control the parton dynamics of short-range nucleon-nucleon scattering. With the aid of exclusive J /ψ production data at the Hadron-Electron Ring Accelerator at DESY, as well as elastic nucleon-nucleon cross sections, we estimate rates for exclusive deuteron photodisintegration at a future Electron-Ion Collider (EIC). Our results, obtained using conservative estimates of EIC integrated luminosities, suggest that center-of-mass energies sNN˜12 GeV2 of the neutron-proton subsystem can be accessed. We argue that the high energies of the EIC can address outstanding dynamical questions regarding the short-range quark-gluon structure of nuclear forces by providing clean gluon probes of such "knockout" exclusive reactions in light and heavy nuclei.
Adler, S S; Ajitanand, N N; Akiba, Y; Al-Jamel, A; Alexander, J; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Averbeck, R; Awes, T C; Babintsev, V; Baldisseri, Alberto; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bjorndal, M T; Boissevain, J G; Borel, H; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Büsching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Comets, M P; Constantin, P; Csanad, M; Csorg}o, T; Cussonneau, J P; D'Enterria, D; Das, K; Dávid, G; Deák, F; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Drachenberg, J L; Drapier, O; Drees, A; Durum, A; Dutta, D; Dzhordzhadze, V; Efremenko, Yu V; Enyo, H; Espagnon, B; Esumi, S; Fields, D E; Finck, C; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Zeev; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fung, S Y; Gadrat, S; Germain, M; Glenn, A; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse-Perdekamp, M; Gustafsson, Hans Åke; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hasuko, K; Hayano, R; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hidas, P; Hiejima, H; Hill, J C; Hobbs, R; Holzmann, W; Homma, K; Hong, B; Hoover, A; Horaguchi, T; Ichihara, T; Ikonnikov, V V; Imai, K; Inaba, M; Inuzuka, M; Isenhower, D; Isenhower, L; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kaneta, M; Kang, J H; Katou, K; Kawabata, T; Kazantsev, A V; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, E; Kim, G B; Kim, H J; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klein-Bösing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Kohara, R; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kunde, G J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Le Bornec, Y; Lebedev, A; Leckey, S; Lee, D M; Leitch, M J; Leite, M A L; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Maguire, C F; Makdisi, Y I; Malakhov, A; Man'ko, V I; Mao, Y; Martínez, G; Masui, H; Matathias, F; Matsumoto, T; McCain, M C; McGaughey, P L; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mukhopadhyay, D; Muniruzzaman, M; Nagamiya, S; Nagle, J L; Nakamura, T; Newby, J; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, H; Okada, K; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Penev, V; Peng, J C; Pereira, H; Peresedov, V; Pierson, A; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qualls, J M; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rykov, V L; Ryu, S S; Saitô, N; Sakaguchi, T; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T A; Shigaki, K; Shimomura, M; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Soldatov, A; Soltz, R A; Sondheim, W E; Sørensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarjan, P; Thomas, T L; Togawa, M; Tojo, J; Torii, H; Towell, R S; Tram, V N; Tserruya, Itzhak; Tsuchimoto, Y; Tydesjo, H; Tyurin, N; Uam, T J; Velkovska, J; Velkovsky, M; Veszpremi, V; Vinogradov, A A; Volkov, M A; Vznuzdaev, E; Wang, X R; Watanabe, Y; White, S N; Willis, N; Wohn, F K; Woody, C L; Xie, W; Yanovich, A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zimányi, J; Zolin, L; Zong, X; van Hecke, H W
2007-01-01
We present transverse momentum (p_T) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at \\sqrts = 200 GeV for four centrality classes. Nucleon-gold collisions were selected by tagging events in which a spectator nucleon was observed in one of two forward rapidity detectors. The spectra and yields were investigated as a function of the number of binary nucleon-nucleon collisions, \
Induced Hyperon-Nucleon-Nucleon Interactions and the Hyperon Puzzle
Wirth, Roland
2016-01-01
We present the first ab initio calculations for $p$-shell hypernuclei including hyperon-nucleon-nucleon (YNN) contributions induced by a Similarity Renormalization Group transformation of the initial hyperon-nucleon interaction. The transformation including the YNN terms conserves the spectrum of the Hamiltonian while drastically improving model-space convergence of the Importance-Truncated No-Core Shell Model, allowing a precise extraction of binding and excitation energies. Results using a hyperon-nucleon interaction at leading order in chiral effective field theory for lower- to mid-$p$-shell hypernuclei show a good reproduction of experimental excitation energies while hyperon binding energies are typically overestimated. The induced YNN contributions are strongly repulsive and we show that they are related to a decoupling of the $\\Sigma$ hyperons from the hypernuclear system, i.e., a suppression of the $\\Lambda$-$\\Sigma$ conversion terms in the Hamiltonian. This is linked to the so-called hyperon puzzle ...
Electromagnetic Excitation of Nucleon Resonances
Tiator, L; Kamalov, S S; Vanderhaeghen, M
2011-01-01
Recent progress on the extraction of electromagnetic properties of nucleon resonance excitation through pion photo- and electroproduction is reviewed. Cross section data measured at MAMI, ELSA, and CEBAF are analyzed and compared to the analysis of other groups. On this basis, we derive longitudinal and transverse transition form factors for most of the four-star nucleon resonances. Furthermore, we discuss how the transition form factors can be used to obtain empirical transverse charge densities. Contour plots of the thus derived densities are shown for the Delta, Roper, S11, and D13 nucleon resonances.
Regularization Methods for Nucleon-Nucleon Effective Field Theory
Steele, James V.; Furnstahl, R. J.
1998-01-01
Attempts to apply effective field theory (EFT) methods to nonrelativistic nucleon-nucleon (NN) scattering have raised questions about the nature and limitations of an EFT expansion when used nonperturbatively. We discuss the characteristics of a meaningful EFT analysis and compare them with traditional approaches to NN scattering. A key feature of an EFT treatment is a systematic expansion in powers of momentum, which we demonstrate using an error analysis introduced by Lepage. A clear graphi...
Structure and Function of Lipase
DEFF Research Database (Denmark)
Skjold-Jørgensen, Jakob
the water-lipid interface, structural movements occurring during activation have been difficult to probeexperimentally. In this work, novel variants of TlL were constructed based on rational design with amutated lid-region in order to elucidate the impact of the lid-residue composition and characteristics...
International Nuclear Information System (INIS)
A surprisingly simple relationship for particle and quark masses is given as m = x*y*me. Thereby y = 1 and x = 1/α, β and β/α for a hypothetic mass m0, the nucleon and the Higgs boson. With y = 4/3 instead y = 1 one obtains the masses of the strange-, charm-, and top quark, with x = β/α and y = 2/π the Z boson and with the π-2 fold thereof the W boson. The aforementioned m0 is the building block for calculating, as integer multiples, all other meson- and baryon masses with better than 2 % accuracy.
Energy Technology Data Exchange (ETDEWEB)
Guillon, B
2005-10-15
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{sup -6} with an overall relative uncertainty better than 10 %, over a momentum transfer range 0.1-1 (GeV/c){sup 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)
Transverse momentum distributions inside the nucleon from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Musch, Bernhard Ulrich
2009-05-29
Nucleons, i.e., protons and neutrons, are composed of quarks and gluons, whose interactions are described by the theory of quantum chromodynamics (QCD), part of the standard model of particle physics. This work applies lattice QCD to compute quark momentum distributions in the nucleon. The calculations make use of lattice data generated on supercomputers that has already been successfully employed in lattice studies of spatial quark distributions (''nucleon tomography''). In order to be able to analyze transverse momentum dependent parton distribution functions, this thesis explores a novel approach based on non-local operators. One interesting observation is that the transverse momentum dependent density of polarized quarks in a polarized nucleon is visibly deformed. A more elaborate operator geometry is required to enable a quantitative comparison to high energy scattering experiments. First steps in this direction are encouraging. (orig.)
Dispersive analysis of the scalar form factor of the nucleon
Hoferichter, M; Kubis, B; Meißner, U -G
2012-01-01
Based on the recently proposed Roy-Steiner equations for pion-nucleon scattering, we derive a system of coupled integral equations for the pi pi --> N-bar N and K-bar K --> N-bar N S-waves. These equations take the form of a two-channel Muskhelishvili-Omnes problem, whose solution in the presence of a finite matching point is discussed. We use these results to update the dispersive analysis of the scalar form factor of the nucleon fully including K-bar K intermediate states. In particular, we determine the correction Delta_sigma=sigma(2M_pi^2)-sigma_{pi N}, which is needed for the extraction of the pion-nucleon sigma term from pi N scattering, as a function of pion-nucleon subthreshold parameters and the pi N coupling constant.
Predicting protein structure classes from function predictions
DEFF Research Database (Denmark)
Sommer, I.; Rahnenfuhrer, J.; de Lichtenberg, Ulrik;
2004-01-01
We introduce a new approach to using the information contained in sequence-to-function prediction data in order to recognize protein template classes, a critical step in predicting protein structure. The data on which our method is based comprise probabilities of functional categories; for given......-to-structure prediction methods....
Energy Technology Data Exchange (ETDEWEB)
Rebreyend, D
2006-10-15
The photoproduction of mesons on the nucleon gives a direct access to its spectroscopy and is a promising way for the study of the structure of the nucleon. The GRAAL experiment uses a tagged and polarized photon beam produced through the Compton diffusion of laser photons on the electrons circulating in the ESRF storage ring. The combination of this photon beam and an efficient detection system has allowed a series of measurements concerning the photoproduction of light mesons on the proton and on the neutron. The first 4 chapters are dedicated to the nucleon spectroscopy: the nucleon models and their consequences on the excited levels are recalled, the experimental technique used is described and the difficulties due to the extraction of relevant data are presented. Highly accurate measurements of cross-sections, {sigma} asymmetry beams and resonance parameters have been performed. The last part is dedicated to the principle of the measurement of the electric dipole momentum of the neutron. (A.C.)
Momentum and coordinate space three-nucleon potentials
Coon, S A
1993-01-01
In this paper we give explicit formulae in momentum and coordinate space for the three-nucleon potentials due to $\\rho$ and $\\pi$ meson exchange, derived from off-mass-shell meson-nucleon scattering amplitudes which are constrained by the symmetries of QCD and by the experimental data. Those potentials have already been applied to nuclear matter calculations. Here we display additional terms which appear to be the most important for nuclear structure. The potentials are decomposed in a way that separates the contributions of different physical mechanisms involved in the meson-nucleon amplitudes. The same type of decomposition is presented for the $\\pi - \\pi$ TM force: the $\\Delta$, the chiral symmetry breaking and the nucleon pair terms are isolated.
The Form Factors of the Nucleons
Energy Technology Data Exchange (ETDEWEB)
Perdrisat, Charles F. [William and Mary College, JLAB
2013-11-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double-polarization experiments, in comparison with with pre-vious unpolarized cross section data. Here we will review the experimental data base in view of the new results for the proton and the neutron, obtained at MIT-Bates, JLab and MAMI. The rapid evolution of phenomenological models triggered by these high- precision experiments will be discussed. In particular, the possibility that the proton is non-spherical in its ground state, and that the transverse charge density are model in- dependently defined in the infinite momentum frame. Likewise, flavor decomposition of the nucleon form factors into dressed u and d quark form factors, may give information about the quark-diquark structure of the nucleon. The current proton radius "crisis" will also be discussed.
The form factors of the nucleons
Perdrisat, C. F.
2013-11-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double-polarization experiments, in comparison with with previous unpolarized cross section data. Here we will review the experimental data base in view of the new results for the proton and the neutron, obtained at MIT-Bates, JLab and MAMI. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed. In particular, the possibility that the proton is non-spherical in its ground state, and that the transverse charge density are model independently defined in the infinite momentum frame. Likewise, flavor decomposition of the nucleon form factors into dressed u and d quark form factors, may give information about the quark-diquark structure of the nucleon. The current proton radius "crisis" will also be discussed.
Correlation Functions and Glass Structure
Chergui, Y.; Nehaoua, N.; Telghemti, B.; Guemid, S.; Deraddji, N. E.; Belkhir, H.; Mekki, D. E.
2011-04-01
This work presents the use of molecular dynamics (MD) and the code of Dl Poly, in order to study the structure of fluoride glass after melting and quenching. We are realized the processing phase liquid-phase, simulating rapid quenching at different speeds to see the effect of quenching rate on the operation of the devitrification. This technique of simulation has become a powerful tool for investigating the microscopic behaviour of matter as well as for calculating macroscopic observable quantities. As basic results, we calculated the interatomic distance, angles and statistics, which help us to know the geometric form and the structure of PbF2. These results are in experimental agreement to those reported in literature.
Nucleon-pion-state contribution in lattice calculations of the nucleon charges $g_A,g_T$ and $g_S$
Bar, Oliver
2016-01-01
We employ leading order covariant chiral perturbation theory to compute the nucleon-pion-state contribution to the 3-point correlation functions one typically measures in lattice QCD to extract the isovector nucleon charges $g_A,g_T$ and $g_S$. We estimate the impact of the nucleon-pion-state contribution on both the plateau and the summation method for lattice simulations with physical pion masses. The nucleon-pion-state contribution results in an overestimation of all charges with both methods. The overestimation is roughly equal for the axial and the tensor charge, and about fifty percent larger for the scalar charge.
WAY TO DETERMINE STIFFNESS FUNCTION OF STRUCTURE
Institute of Scientific and Technical Information of China (English)
WANG De-ming; GAI Bing-zheng
2005-01-01
For calculating the stiffness function of a structure, the differential equation of the vibration of the structure was divided into the differential equation on the original stiffness function that was known, and Fredholm integral equation of the first kind on the undetermined stiffness function that was unknown. And the stable solutions of the integral equation, when the smooth factor was equal to zero, was solved by the extrapolation with p smooth factors. So the stiffness function of the structure is obtained. Applied examples show that the method is feasible and effective.
Nucleonic helicity distributions revisited with an emphasis on their evolutions and twists
Indian Academy of Sciences (India)
Rajen Kundu
2014-12-01
In this work, we uphold and extend the formalism advocated by us more than a decade ago in order to extract information on various distribution functions describing nucleonic helicity structure and calculate a complete set of splitting functions relevant for their quantum chromodynamics (QCD) evolutions using light-front Hamiltonian perturbation theory in light front gauge + = 0. Twist-two structures of the helicity distributions are self-evident in our calculation. Sum rules associated with these helicity distributions are also verified in a frame-independent way.
Pion structure function in nuclear medium
Suzuki, Katsuhiko
1995-01-01
We study the pion structure function in nuclear medium using the Nambu and Jona-Lasinio model, and its implication for the nuclear pion enhancement of the sea quark distribution in nuclei. By using the operator product expansion, medium effect of the nuclear matter is incorporated in calculations of the twist-2 operators. We find density dependence of the pion structure function is rather weak around the nuclear matter density. We also discuss how the medium modification of the pion structure...
Structural Induction Principles for Functional Programmers
Caldwell, James
2013-01-01
User defined recursive types are a fundamental feature of modern functional programming languages like Haskell, Clean, and the ML family of languages. Properties of programs defined by recursion on the structure of recursive types are generally proved by structural induction on the type. It is well known in the theorem proving community how to generate structural induction principles from data type declarations. These methods deserve to be better know in the functional programming community. ...
The LIGNUM functional-structural tree model
Perttunen, Jari
2009-01-01
The aim of this thesis was to construct a single tree model that builds a bridge between traditional process based tree models and detailed, three-dimensional architectural tree models. The result of the thesis, the functional-structural tree model LIGNUM, integrates both the functional and the structural aspects of woody arborescent plants in a single generic modelling framework. The thesis consists of five articles and the summary part. The first article presents the model structure of...
Nucleon-nucleon interaction and the quark model
International Nuclear Information System (INIS)
The NN phase shifts are calculated using the quark model with a QCD inspired quark-quark force. The short range part of the NN force is given by quark and gluon exchange. The long range part is described by π and σ-meson exchange. The data fitted in the model are five values connected with three quarks only: the nucleon mass, the Δ mass, the root mean square radius of the charge distribution of the proton including the pion cloud, the π-N and the σ-N coupling constant at zero momentum transfer. The 1S and 3S phase shifts are nicely reproduced. The short range repulsion is decisively influenced by the node in the [42]r relative wave function. Very important is the colour magnetic quark-quark force which enlarges the [42]r admixture. In the OBEP's the short range repulsion is connected with the exchange of the ω-meson. But to reproduce the short range repulsion one had to blow up the ω-N coupling constant by a factor 2 to 3 compared to flavour SU3. With quark and gluon exchange the best fit to the ω-N coupling constant lies close to the SU3 flavour value. This fact strongly supports the notion that the real nature of the short range repulsion of the NN interaction have been found
Electroexcitation of nucleon resonances
Aznauryan, I G
2011-01-01
We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited states, which have been measured in a range of Q2 up to 8 and 4.5 GeV2 for the Delta(1232)P33, N(1535)S11 and N(1440)P11, N(1520)D13}, respectively. These results have been confronted with calculations based on lattice QCD, large-Nc relations, perturbative QCD (pQCD), and QCD-inspired models. The amplitudes for the Delta(1232) indicate large pion-cloud contributions at low Q2 and don't show any sign of approaching the pQCD regime for Q2 0.5 GeV2, confirming a long-standing prediction of the constituent quark model. The interpretation of the moments of resonance transition form factors in terms of transition transverse charge distributions in infinite momentum frame is presented.
A quark-model NN interaction and its application to the three-nucleon and nuclear-matter problems
International Nuclear Information System (INIS)
Baryon-baryon interactions of the complete baryon octet (B8) are investigated in a unified framework of the (3q)-(3q) resonating-group method, which employs the spin-flavor SU6 quark-model were functions. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon interaction. Some characteristic features of the B8B8 interactions predicted by the most recent model fss2 are discussed. The nucleon-nucleon sector of this quark-model potential is used to calculate G-matrices for nuclear and neutron matter, and to solve the Faddeev equation of the three-nucleon bound state. The calculated binding energy for 3H is the closest to the experiment among many results obtained by detailed Faddeev calculations employing modern realistic nucleon-nucleon potentials. (author)
Changes in gastrointestinal tract function and structure in functional dyspepsia.
Vanheel, Hanne; Farré, Ricard
2013-03-01
Functional dyspepsia is an extremely common disorder of gastrointestinal function. The disorder is thought to be heterogeneous, with different pathophysiological mechanisms underlying varied symptom patterns. A diversity of changes in gastrointestinal tract function and structure has been described in functional dyspepsia. These involve alterations in the stomach, such as impaired accommodation, delayed gastric emptying and hypersensitivity, and alterations in the duodenum, such as increased sensitivity to duodenal acid and/or lipids and low-grade inflammation. In this Review, we summarize all these abnormalities in an attempt to provide an integrated overview of the pathophysiological mechanisms in functional dyspepsia. PMID:23318268
The structure and function of catalytic RNAs
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Before the discovery of ribozymes,RNA had been proposed to function as a catalyst,based on the discovery that RNA folded into high-ordered structures as protein did.This hypothesis was confirmed in the 1980s,after the discovery of Tetrahymena group I intron and RNase P ribozyme.There have been about ten ribozymes identified during the past thirty years,as well as the fact that ribosomes function as ribozymes.Advances have been made in understanding the structures and functions of ribozymes,with numerous crystal structures resolved in the past years.Here we review the structure-function relationship of both small and large ribozymes,especially the structural basis of their catalysis.
The structure and function of catalytic RNAs
Institute of Scientific and Technical Information of China (English)
WU QiJia; HUANG Lin; ZHANG Yi
2009-01-01
Before the discovery of ribozymes, RNA had been proposed to function as a catalyst, based on the discovery that RNA folded into high-ordered structures as protein did. This hypothesis was confirmed in the 1980s, after the discovery of Tetrahymena group I intron and RNase P ribozyme. There have been about ten ribozymes identified during the past thirty years, as well as the fact that ribosomes function as ribozymes. Advances have been made in understanding the structures and functions of ribozymes, with numerous crystal structures resolved in the past years. Here we review the structure-function re-lationship of both small and large ribozymes, especially the structural basis of their catalysis.
The extraction of the spin structure function, g2 (and g1) at low Bjorken x
International Nuclear Information System (INIS)
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.
Electroexcitation of nucleon resonances
Energy Technology Data Exchange (ETDEWEB)
Inna Aznauryan, Volker D. Burkert
2012-01-01
We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited states, which have been measured in a range of Q2 up to 8 and 4.5 GeV2 for the Delta(1232)P33, N(1535)S11 and N(1440)P11, N(1520)D13, respectively. These results have been confronted with calculations based on lattice QCD, large-Nc relations, perturbative QCD (pQCD), and QCD-inspired models. The amplitudes for the Delta(1232) indicate large pion-cloud contributions at low Q2 and don't show any sign of approaching the pQCD regime for Q2<7 GeV2. Measured for the first time, the electroexcitation amplitudes of the Roper resonance, N(1440)P11, provide strong evidence for this state as a predominantly radial excitation of a three-quark (3q) ground state, with additional non-3-quark contributions needed to describe the low Q2 behavior of the amplitudes. The longitudinal transition amplitude for the N(1535)S11 was determined and has become a challenge for quark models. Explanations may require large meson-cloud contributions or alternative representations of this state. The N(1520)D13 clearly shows the rapid changeover from helicity-3/2 dominance at the real photon point to helicity-1/2 dominance at Q2 > 0.5 GeV2, confirming a long-standing prediction of the constituent quark model. The interpretation of the moments of resonance transition form factors in terms of transition transverse charge distributions in infinite momentum frame is presented.
Leading chiral three-nucleon forces along isotope chains in the calcium region
Somà, V; Barbieri, C; Navrátil, P; Duguet, T
2013-01-01
Three-nucleon forces (3NFs), and in particular terms of the Fujita-Miyazawa type, strongly influence the structure of neutron-rich exotic isotopes. Ab-initio calculations have shown that chiral two- and three-nucleon interactions correctly reproduce binding energy systematics and neutron driplines of oxygen and nearby isotopes. Exploiting the novel self-consistent Gorkov-Green's function approach, we present the first investigation of Ar, K, Ca, Sc and Ti isotopic chains. Leading chiral 3N interactions are mandatory to reproduce the trend of binding energies throughout these chains and to obtain a good description of two-neutron separation energies. At the same time, nuclei in this mass region are systematically overbound by about 40 MeV and the $N=20$ magic gap is significantly overestimated. We conclude that ab-initio many-body calculations of mid-mass isotopic chains challenge modern theories of elementary nuclear interactions.
Nuclear medium modification of the F{sub 2}(x,Q{sup 2}) structure function
Energy Technology Data Exchange (ETDEWEB)
Sajjad Athar, M., E-mail: sajathar@gmail.co [Department of Physics, Aligarh Muslim University, Aligarh 202 002 (India); Ruiz Simo, I.; Vicente Vacas, M.J. [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia - CSIC, 46100 Burjassot (Valencia) (Spain)
2011-05-01
We study the nuclear effects in the electromagnetic structure function F{sub 2}(x,Q{sup 2}) in the deep inelastic lepton-nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations. The ratios R{sub F}{sub 2}{sup A}(x,Q{sup 2})=(2F{sub 2}{sup A}(x,Q{sup 2}))/(AF{sub 2}{sup D}(x,Q{sup 2})) are obtained and compared with recent JLab results for light nuclei with special attention to the slope of the x distributions. This magnitude shows a non-trivial A dependence and it is insensitive to possible normalization uncertainties. The results have also been compared with some of the older experiments using intermediate mass nuclei.
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
Progress on nuclear modifications of structure functions
Kumano, S
2016-01-01
We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrino-oscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function $b_1$ is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact ...
New Parametrizations for the Photon Structure Function
International Nuclear Information System (INIS)
In the last year four new parametrizations of the Hadronic Photon Structure Function at Next to Leading Order have appeared. In this talk, I briefly review the main features of the three of them: the FFNSCJK, CJK and AFG. (author)
Structural and functional properties of designed globins
Indian Academy of Sciences (India)
Yasuhiro Isogai; Anna Ishii; Manabu Ishida; Masahiro Mukai; Motonori Ota; Ken Nishikawa; Tetsutaro Iizuka
2000-06-01
De novo design of artificial proteins is an essential approach to elucidate the principles of protein architecture and to understand specific functions of natural proteins and also to yield novel molecules for medical and industrial aims. We have designed artificial sequences of 153 amino acids to fit the main-chain framework of the sperm whale myoglobin structure based on the knowledge-based energy functions to evaluate the compatibility between protein tertiary structures and amino acid sequences. The synthesized artificial globins bind a single heme per protein molecule as designed, which show well-defined electrochemical and spectroscopic features characteristic of proteins with a low-spin heme. Redox and ligand binding reactions of the artificial heme proteins were investigated and these heme-related functions were found to vary with their structural uniqueness. Relationships between the structural and functional properties are discussed.
The problem of nucleon production in the quark parton model
International Nuclear Information System (INIS)
Quark fragmentation into hadrons, esp. nucleons, is studied fitting empirical fragmentation functions to e+e- annihilation data. We find fragmentation functions deviating from counting rule predictions as well as from scaling due to the threshold in kaon and nucleon production. Using these fragmentation functions we study particle production ratios in ep and large transverse momentum hadronic reactions. In both cases we find the ratios p/π+ and antip/π- to agree roughly in magnitude with the measured ratios. The model is however inconsistent with the transverse momentum-12 behaviour of large transverse momentum proton spectra. (author)
Spin Structure Functions of the Deuteron Measured with CLAS in and above the Resonance Region
Energy Technology Data Exchange (ETDEWEB)
Kahanawita Dharmawardane
2004-05-01
Spin structure functions of the nucleon in the region of large x and small to moderate Q{sup 2} continue to be of high current interest. The first moment of the spin structure function g{sub 1}, {Gamma}{sub 1}, goes through a rapid transition from the photon point (Q{sup 2}=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. The interesting behavior in the transition region is dominated by baryon resonance excitations. We concluded an experiment to measure these observables for deuterium as part of the ''EG1'' run group in Jefferson Lab's Hall B. We used a highly polarized electron beam with energies from 1.6 GeV to 5.7 GeV and a cryogenic polarized ND{sub 3} target together with the CEBAF Large Acceptance Spectrometer (CLAS) to accumulate over 11 billion events. In this thesis, we present results for the spin structure function g{sub 1}{sup d} (x,Q{sup 2}), as well as its first moment, {Gamma}{sub 1}{sup d}(Q{sup 2}) in and above the resonance region over a Q{sup 2} range from 0.05 to 5 Gev{sup 2}, based on the data taken with beam energies of 1.6 and 5.7 GeV. We also extract the behavior of A{sub 1}{sup d}(x) at large x. Our data are consistent with the Hyperfine-perturbed quark model calculation which predicts that A{sub 1}{sup d} (x {yields} 1) {yields} 1. We also see evidence for duality in g{sub 1}{sup d} (x, Q{sup 2}) at Q{sup 2} > GeV{sup 2}.
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.
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
Zinc finger structure-function in Ikaros
Institute of Scientific and Technical Information of China (English)
Marvin; A; Payne
2011-01-01
The zinc finger motif was used as a vehicle for the initial discovery of Ikaros in the context of T-cell differentiation and has been central to all subsequent analyses of Ikaros function.The Ikaros gene is alternately spliced to produce several isoforms that confer diversity of function and consequently have complicated analysis of the function of Ikaros in vivo.Key features of Ikaros in vivo function are associated with six C2H2 zinc fingers;four of which are alternately incorporated in the production of the various Ikaros isoforms.Although no complete structures are available for the Ikaros protein or any of its family members,considerable evidence has accumulated about the structure of zinc fingers and the role that this structure plays in the functions of the Ikaros family of proteins.This review summarizes the structural aspects of Ikaros zinc fingers,individually,and in tandem to provide a structural context for Ikaros function and to provide a structural basis to inform the design of future experiments with Ikaros and its family members.
Structure and Structure-activity Relationship of Functional Organic Molecules
Institute of Scientific and Technical Information of China (English)
2011-01-01
@@ Research theme The group is made up of junior scientists from the State Key Laboratory of Elemento-organic Chemistry, Nankai University.The scientists focus their studis on the structure and structure-activity relationship of functional organic molecules not only because it has been the basis of their research, but also because the functional study of organic compounds is now a major scientific issue for organic chemists around the world.
2004 Structural, Function and Evolutionary Genomics
Energy Technology Data Exchange (ETDEWEB)
Douglas L. Brutlag Nancy Ryan Gray
2005-03-23
This Gordon conference will cover the areas of structural, functional and evolutionary genomics. It will take a systematic approach to genomics, examining the evolution of proteins, protein functional sites, protein-protein interactions, regulatory networks, and metabolic networks. Emphasis will be placed on what we can learn from comparative genomics and entire genomes and proteomes.
Nucleon Helicity and Transversity Parton Distributions from Lattice QCD
Chen, Jiunn-Wei; Ji, Xiangdong; Lin, Huey-Wen; Zhang, Jian-Hui
2016-01-01
We present the first lattice-QCD calculation of the isovector polarized parton distribution functions (both helicity and transversity) using the large-momentum effective field theory (LaMET) approach for direct Bjorken-$x$ dependence. We first review the detailed steps of the procedure in the unpolarized case, then generalize to the helicity and transversity cases. We also derive a new mass-correction formulation for all three cases. We then compare the effects of each finite-momentum correction using lattice data calculated at $M_\\pi\\approx 310$ MeV. Finally, we discuss the implications of these results for the poorly known antiquark structure and predict the sea-flavor asymmetry in the transversely polarized nucleon.
Running Masses in the Nucleon and its Resonances
Roberts, Craig D
2015-01-01
An overarching scientific challenge for the coming decade is to discover the meaning of confinement, its relationship to dynamical chiral symmetry breaking (DCSB) - the origin of visible mass - and the connection between them. In progressing toward meeting this challenge, significant progress has been made using continuum methods in QCD. For example, a novel understanding of gluon and quark confinement and its consequences has begun to emerge from quantum field theory; a clear picture is being drawn of how hadron masses emerge dynamically in a universe with light quarks; and ground-state hadron wave functions with a direct connection to QCD are becoming available, which reveal that quark-quark correlations are crucial in hadron structure. There is growing experimental support for this body of predictions in both elastic and nucleon-to-resonance-transition form factors.
Valence quark polarization in the nucleon and the deuteron data
Arash, Firooz; Taghavi-Shahri, Fatemeh
2008-10-01
Within the framework of the so-called valon model, we argue that a substantial part of the nucleon spin, about 40%, is carried by the polarized valence quarks. The remaining is the result of cancelations between gluon polarization and the orbital angular momentum, where the gluon polarization is the dominant one. It is shown that the sea quark contributions to the spin of any hadron is simply marginal and consistent with zero. Our findings point to a substantially smaller value for a8 than inferred from hyperon β decay, suggesting that full SU (3) symmetric assumption needs to be reconsidered. New and emerging experimental data tend to support this finding. Finally, we show that within the model presented here the experimental data on the polarized structure functions g1p,n,d are reproduced.
Study of the derivative expansions for the nuclear structure functions
Simo, I Ruiz
2008-01-01
We study the convergence of the series expansions sometimes used in the analysis of the nuclear effects in Deep Inelastic Scattering (DIS) proccesses induced by leptons. The recent advances in statistics and quality of the data, in particular for neutrinos calls for a good control of the theoretical uncertainties of the models used in the analysis. Using realistic nuclear spectral functions which include nucleon correlations, we find that the convergence of the derivative expansions to the full results is poor except at very low values of $x$.
International Nuclear Information System (INIS)
Coupled-channels optical model approach built on the wave functions of the soft-rotator nuclear Hamiltonian is applied for the self-consistent analyses of the low-lying collective nuclear level structure and nucleon interaction with even-even nuclei in a wide A- mass region. It succeeds to describe available experimental data and B(Eλ) γ-transitions with reasonable accuracy. Along with the account of the global optical potential form and relativistic kinematics, present method was proved to be a powerful tool for studies of nucleon-induced reaction data. (author)
Structure functions in the chiral bag model
Energy Technology Data Exchange (ETDEWEB)
Sanjose, V.; Vento, V.
1989-07-13
We calculate the structure functions of an isoscalar nuclear target for the deep inelastic scattering by leptons in an extended version of the chiral bag model which incorporates the qanti q structure of the pions in the cloud. Bjorken scaling and Regge behavior are satisfied. The model calculation reproduces the low-x behavior of the data but fails to explain the medium- to large-x behavior. Evolution of the quark structure functions seem inevitable to attempt a connection between the low-energy models and the high-energy behavior of quantum chromodynamics. (orig.).
Clustering aspects in nuclear structure functions
Hirai, M; Saito, K; Watanabe, T
2010-01-01
For understanding an anomalous nuclear effect experimentally observed for the beryllium-9 nucleus at the Thomas Jefferson National Accelerator Facility (JLab), clustering aspects are studied in structure functions of deep inelastic lepton-nucleus scattering by using momentum distributions calculated in antisymmetrized (or fermionic) molecular dynamics (AMD) and also in a simple shell model for comparison. According to the AMD, the Be-9 nucleus consists of two alpha-like clusters with a surrounding neutron. The clustering produces high-momentum components in nuclear wave functions, which affects nuclear modifications of the structure functions. We investigated whether clustering features could appear in the structure function F_2 of Be-9 along with studies for other light nuclei. We found that nuclear modifications of F_2 are similar in both AMD and shell models within our simple convolution description although there are slight differences in Be-9. It indicates that the anomalous Be-9 result should be explain...
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.
Measurement of the proton structure function F2 at low Q2 in QED Compton scattering at HERA
Aktas, A.; Andreev, V.; Anthonis, T.; Asmone, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Berndt, T.; Bizot, J. C.; Böhme, J.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brisson, V.; Bröker, H.-B.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Chekelian, V.; Collard, C.; Contreras, J. G.; Coppens, Y. R.; Coughlan, J. A.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E. A.; Diaconu, C.; Dingfelder, J.; Dodonov, V.; Dubak, A.; Duprel, C.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Flügge, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garutti, E.; Garvey, J.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gorbounov, S.; Grab, C.; Grässler, H.; Greenshaw, T.; Gregori, M.; Grindhammer, G.; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Heremans, R.; Herrera, G.; Herynek, I.; Heuer, R.-D.; Hildebrandt, M.; Hiller, K. H.; Höting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keller, N.; Kennedy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Koblitz, B.; Korbel, V.; Kostka, P.; Koutouev, R.; Kropivnitskaya, A.; Kroseberg, J.; Kückens, J.; Kuhr, T.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebedev, A.; Leißner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lueders, H.; Lüke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marks, J.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Michine, S.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morozov, I.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Ossoskov, G.; Ozerov, D.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Plačakytė, R.; Pöschl, R.; Portheault, B.; Povh, B.; Raicevic, N.; Ratiani, Z.; Reimer, P.; Reisert, B.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Scheins, J.; Schilling, F.-P.; Schleper, P.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Uraev, A.; Urban, M.; Usik, A.; Utkin, D.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Winter, G.-G.; Wissing, Ch.; Woehrling, E.-E.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zohrabyan, H.; Zomer, F.; H1 Collaboration
2004-09-01
The proton structure function F2 (x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q2, down to 0.5 GeV2, and Bjorken x up to ∼0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton-nucleon scattering experiments.
The proteome: structure, function and evolution.
Fleming, Keiran; Kelley, Lawrence A; Islam, Suhail A; MacCallum, Robert M; Muller, Arne; Pazos, Florencio; Sternberg, Michael J E
2006-03-29
This paper reports two studies to model the inter-relationships between protein sequence, structure and function. First, an automated pipeline to provide a structural annotation of proteomes in the major genomes is described. The results are stored in a database at Imperial College, London (3D-GENOMICS) that can be accessed at www.sbg.bio.ic.ac.uk. Analysis of the assignments to structural superfamilies provides evolutionary insights. 3D-GENOMICS is being integrated with related proteome annotation data at University College London and the European Bioinformatics Institute in a project known as e-protein (http://www.e-protein.org/). The second topic is motivated by the developments in structural genomics projects in which the structure of a protein is determined prior to knowledge of its function. We have developed a new approach PHUNCTIONER that uses the gene ontology (GO) classification to supervise the extraction of the sequence signal responsible for protein function from a structure-based sequence alignment. Using GO we can obtain profiles for a range of specificities described in the ontology. In the region of low sequence similarity (around 15%), our method is more accurate than assignment from the closest structural homologue. The method is also able to identify the specific residues associated with the function of the protein family.
Stopped nucleons in configuration space
Bialas, Andrzej; Koch, Volker
2016-01-01
In this note, using the colour string model, we study the configuration space distribution of stopped nucleons in heavy-ion collisions. We find that the stopped nucleons from the target and the projectile end up separated from each other by the distance increasing with the collision energy. In consequence, for the center of mass energies larger than 6 or 10 GeV (depending on the details of the model) it appears that the system created is not in thermal and chemical equilibrium, and the net baryon density reached is likely not much higher than that already present in the colliding nuclei.
Hammer events, neutrino energies, and nucleon-nucleon correlations
Weinstein, L B; Piasetzky, E
2016-01-01
Neutrino oscillation measurements depend on a difference between the rate of neutrino-nucleus interactions at different neutrino energies or different distances from the source. Knowledge of the neutrino energy spectrum and neutrino-detector interactions are crucial for these experiments. Short range nucleon-nucleon correlations in nuclei (SRC) affect properties of nuclei. The ArgoNeut liquid Argon Time Projection Chamber (lArTPC) observed neutrino-argon scattering events with two protons back-to-back in the final state ("hammer" events) which they associated with SRC pairs. The MicroBoone lArTPC will measure far more of these events. We simulate hammer events using two simple models. We use the well-known electron-nucleon cross section to calculate e-argon interactions where the e- scatters from a proton, ejecting a pi+, and the pi+ is then absorbed on a moving deuteron-like $np$ pair. We also use a model where the electron excites a nucleon to a Delta, which then deexcites by interacting with a second nucle...
GRASPs in Golgi Structure and Function
Directory of Open Access Journals (Sweden)
Xiaoyan eZhang
2016-01-01
Full Text Available The Golgi apparatus is a central intracellular membrane organelle for trafficking and modification of proteins and lipids. Its basic structure is a stack of tightly aligned flat cisternae. In mammalian cells, dozens of stacks are concentrated in the pericentriolar region and laterally connected to form a ribbon. Despite extensive research in the last decades, how this unique structure is formed and why its formation is important for proper Golgi functioning remain largely unknown. The Golgi ReAssembly Stacking Proteins, GRASP65 and GRASP55, are so far the only proteins shown to function in Golgi stacking. They are peripheral membrane proteins on the cytoplasmic face of the Golgi cisternae that form trans-oligomers through their N-terminal GRASP domain, and thereby function as the glue to stick adjacent cisternae together into a stack and to link Golgi stacks into a ribbon. Depletion of GRASPs in cells disrupts the Golgi structure and results in accelerated protein trafficking and defective glycosylation. In this minireview we summarize our current knowledge on how GRASPs function in Golgi structure formation and discuss why Golgi structure formation is important for its function.
Wave equation for a composite nucleon
International Nuclear Information System (INIS)
A two-component Pauli equation for a composite model of the nucleon is derived using a relativistically covariant quark model. Scalar-isoscalar, vector-isoscalar, vector-isovector, and electromagnetic external potentials are considered. For the vector fields we find anomalous ''magnetic moments,'' which are simply related to the corresponding electromagnetic κ. The Dirac equation, even if supplemented by anomalous magnetic moments, is found to fail beginning with the Darwin term. However, in Dirac phenomenology, the low-order errors can be compensated by the strengths and functional shapes of the assumed potentials
Wave equation for a composite nucleon
Energy Technology Data Exchange (ETDEWEB)
Achtzehnter, J.; Wilets, L.
1988-07-01
A two-component Pauli equation for a composite model of the nucleon is derived using a relativistically covariant quark model. Scalar-isoscalar, vector-isoscalar, vector-isovector, and electromagnetic external potentials are considered. For the vector fields we find anomalous ''magnetic moments,'' which are simply related to the corresponding electromagnetic kappa. The Dirac equation, even if supplemented by anomalous magnetic moments, is found to fail beginning with the Darwin term. However, in Dirac phenomenology, the low-order errors can be compensated by the strengths and functional shapes of the assumed potentials.
KN Scattering and the Nucleon Strangeness Radius
Ramsey-Musolf, M. J.; Hammer, H. -W.
1997-01-01
The leading non-zero electric moment of the nucleon strange-quark vector current is the mean square strangeness radius, $$. We evaluate the lightest OZI-allowed contribution to $$, arising from the kaon cloud, using dispersion relations. Drawing upon unitarity constraints as well as $K^{+}N$ scattering and $e^+e^-\\to K\\bar{K}$ cross section data, we find the structure of this contribution differs significantly from that suggested by a variety of QCD-inspired model calculations. In particular,...
Dispersion-theoretical analysis of the nucleon electromagnetic form factors
Energy Technology Data Exchange (ETDEWEB)
Belushkin, M.
2007-09-29
The structure of the proton and the neutron is of fundamental importance for the study of the strong interaction dynamics over a wide range of momentum transfers. The nucleon form factors encode information on the internal structure of the nucleon as probed by the electromagnetic interaction, and, to a certain extent, reflect the charge and magnetisation distributions within the proton and the neutron. In this thesis we report on our investigation of the electromagnetic form factors of the proton and the neutron with dispersion relation techniques, including known experimental input on the {pi}{pi}, K anti K and the {rho}{pi} continua and perturbative QCD constraints. We include new experimental data on the pion form factor and the nucleon form factors in our simultaneous analysis of all four form factors in both the space- and the timelike regions for all momentum transfers, and perform Monte- Carlo sampling in order to obtain theoretical uncertainty bands. Finally, we discuss the implications of our results on the pion cloud of the nucleon, the nucleon radii and the Okubo-Zweig-Iizuka rule, and present our results of a model-independent approach to estimating two-photon effects in elastic electron-proton scattering. (orig.)
The Nucleon as a Holographic Cheshire Cat
Zahed, Ismail
2014-01-01
The Cheshire cat principle emerges naturally from the holographic approach of the nucleon in terms of a bulk instanton. The cat hides in the holographic direction. I briefly review the one-nucleon problem in the holographic limit.
The nucleon as a holographic Cheshire cat
International Nuclear Information System (INIS)
The Cheshire cat principle emerges naturally from the holographic approach of the nucleon in terms of a bulk instanton. The cat hides in the holographic direction. I briefly review the one-nucleon problem in the holographic limit
Electromagnetic Form Factors of the Nucleon
Bijker, R
1997-01-01
We reanalyze the world data on the electromagnetic form factors of the nucleon. The calculations are performed in the framework of an algebraic model of the nucleon combined with vector meson dominance.
The two-nucleon t-matrices from inverse scattering
International Nuclear Information System (INIS)
The Marchenko inverse-scattering method has been used to determine the input potential functions to Lippmann-Schwinger equations for the two-nucleaon t-matrices in uncoupled channels. Two-nucleon phase shifts as measured, and as given by the Reid soft-core potential, have been used to specify rational functions for the associated S-matrices and which facilitate use of the inversion method. The Reid-potential results serve as a test of the inversion since the potential and its t-marix on- and off-shell are known exactly. That test gives a qualitative insight into the interdependencies between phase shifts, potentials and properties of the two-nucleon t-matrices. Furthermore, it makes credible the two-nucleon t-matrices obtained using measured phase shifts under the same approximations. (orig.)
Nuclear medium effects in $F_{2A}^{EM}(x,Q^2)$ and $F_{2A}^{Weak}(x,Q^2)$ structure functions
Haider, H; Athar, M Sajjad; Singh, S K; Simo, I Ruiz
2016-01-01
Recent phenomenological analysis of experimental data on DIS processes induced by charged leptons and neutrinos/antineutrinos beams on nuclear targets by CTEQ collaboration has confirmed the observation of CCFR and NuTeV collaborations, that weak structure function $F_{2A}^{Weak} (x,Q^2)$ is different from electromagnetic structure function $F_{2A}^{EM} (x,Q^2)$ in a nucleus like iron, specially in the region of low $x$ and $Q^2$. In view of this observation we have made a study of nuclear medium effects on $F_{2A}^{Weak} (x,Q^2)$ and $F_{2A}^{EM} (x,Q^2)$ for a wide range of $x$ and $Q^2$ using a microscopic nuclear model. We have considered Fermi motion, binding energy, nucleon correlations, mesonic contributions from pion and rho mesons and shadowing effects to incorporate nuclear medium effects. The calculations are performed in a local density approximation using a relativistic nucleon spectral function which includes nucleon correlations. The numerical results in the case of iron nucleus are compared wi...
Precision nucleon-nucleon potential at fifth order in the chiral expansion
Epelbaum, E; Meißner, U -G
2014-01-01
We present a nucleon-nucleon potential at fifth order in chiral effective field theory. We find a substantial improvement in the description of nucleon-nucleon phase shifts as compared to the fourth-order results of Ref. [E. Epelbaum, H. Krebs, U.-G. Mei{\\ss}ner, arXiv:1412.0142 [nucl-th
Measurements of the longitudinal structure function and |$V_{cs}$| in the CCFR experiment
Yang, U K; Arroyo, C G; Bazarko, A O; Bernstein, R H; Bodek, Arie; Bolton, T; Budd, H S; Conrad, J; Harris, D A; Johnson, R A; Kim, J H; King, B J; Kinnel, T; Lamm, M J; Lefmann, W C; Marsh, W; McFarland, K S; Mishra, S R; Naples, D; Quintas, P Z; Romosan, A; Sakumoto, W K; Schellman, H; Sciulli, F J; Seligman, W G; Shaevitz, M H; Smith, W H; Spentzouris, P; Stern, E G; Vakili, M
1998-01-01
Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F_2, xF_3(nu), xF_3(nubar) and R(longitudinal) in the kinematic region 0.01
$\\chi$EFT studies of few-nucleon systems: a status report
Energy Technology Data Exchange (ETDEWEB)
Schiavilla, Rocco [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)
2016-06-01
A status report on $\\chi$EFT studies of few-nucleon electroweak structure and dynamics is provided, including electromagnetic elastic form factors of few-nucleon systems, the $pp$ weak fusion and muon weak captures on deuteron and $^3$He, and a number of parity-violating processes induced by hadronic weak interactions.
Momentum Distribution of a Fragment and Nucleon Removal Cross Section in Halo Nucleus Reaction
Institute of Scientific and Technical Information of China (English)
2002-01-01
Recently the research on the halo structure of drip-line nuclei has attracted much attention both inexperiment and theory. It has shown that some nuclei have one or more halo nucleons. Within the few body Glauber model, the momentum distribution of a fragment and nucleon removalcross section in the halo nucleus reaction have been derived. We extend to the reactions dealing with halo
$\\chi$EFT studies of few-nucleon systems: a status report
Schiavilla, R
2015-01-01
A status report on $\\chi$EFT studies of few-nucleon electroweak structure and dynamics is provided, including electromagnetic form factors of few-nucleon systems, the $pp$ weak fusion and muon weak captures on deuteron and $^3$He, and a number of parity-violating processes induced by hadronic weak interactions.
Structural methods for studying IRES function.
Kieft, Jeffrey S; Costantino, David A; Filbin, Megan E; Hammond, John; Pfingsten, Jennifer S
2007-01-01
Internal ribosome entry sites (IRESs) substitute RNA sequences for some or all of the canonical translation initiation protein factors. Therefore, an important component of understanding IRES function is a description of the three-dimensional structure of the IRES RNA underlying this mechanism. This includes determining the degree to which the RNA folds, the global RNA architecture, and higher resolution information when warranted. Knowledge of the RNA structural features guides ongoing mechanistic and functional studies. In this chapter, we present a roadmap to structurally characterize a folded RNA, beginning from initial studies to define the overall architecture and leading to high-resolution structural studies. The experimental strategy presented here is not unique to IRES RNAs but is adaptable to virtually any RNA of interest, although characterization of RNA-protein interactions requires additional methods. Because IRES RNAs have a specific function, we present specific ways in which the data are interpreted to gain insight into that function. We provide protocols for key experiments that are particularly useful for studying IRES RNA structure and that provide a framework onto which additional approaches are integrated. The protocols we present are solution hydroxyl radical probing, RNase T1 probing, native gel electrophoresis, sedimentation velocity analytical ultracentrifugation, and strategies to engineer RNA for crystallization and to obtain initial crystals. PMID:17913644
DIS structure functions from the saturation model
Golec-Biernat, K.
2000-01-01
We present a description of inclusive and diffractive structure functions in DIS at small $x$, using a model based on high energy factorization. In this model the two processes have physical interpretation in terms of the virtual photon wave function and the dipole cross section. We postulate the dipole cross section form in a way in which unitarity is taken into account. A good description of data (including DIS diffraction) is obtained after determining three parameters of the dipole cross ...
Leading chiral logarithms for the nucleon mass
Energy Technology Data Exchange (ETDEWEB)
Vladimirov, Alexey A.; Bijnens, Johan [Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE 223 62 Lund (Sweden)
2016-01-22
We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the LLog series for the nucleon mass within the heavy baryon theory. The presented results are the first example of LLog calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass.
Gluon Spin Contribution to The Nucleon Spin
Energy Technology Data Exchange (ETDEWEB)
Arash, Firooz, E-mail: farash@cic.aut.ac.i [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of); Shahveh, Abolfazl [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of); Taghavi-Shahri, Fateme [School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM) P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
2010-10-15
We have calculated {delta}g/g in the nucleon at all measured kinematics. The smallness of {delta}g/g in the measured kinematics should not be interpreted as the the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, {Delta}g(Q{sup 2}) can be sizable.
Gluon Spin Contribution to The Nucleon Spin
Arash, Firooz; Shahveh, Abolfazl; Taghavi-Shahri, Fateme
2010-10-01
We have calculated δg/ g in the nucleon at all measured kinematics. The smallness of δg/ g in the measured kinematics should not be interpreted as the the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δ g( Q2) can be sizable.
Gluon Spin Contribution to The Nucleon Spin
International Nuclear Information System (INIS)
We have calculated δg/g in the nucleon at all measured kinematics. The smallness of δg/g in the measured kinematics should not be interpreted as the the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δg(Q2) can be sizable.
Nucleon mean free path in nuclear matter
International Nuclear Information System (INIS)
In calculations of nuclear reaction yields at incident energies of some tens of MeV consistently better agreement with experiments is obtained by assuming a nucleon mean free path in nuclear matter longer than that deduced from the Fermi gas model and free nucleon-nucleon cross sections. (Auth.)
K^* Mesons and Nucleon Strangeness
Barz, L. L.; Forkel, H.; Hammer, H. -W.; Navarra, F. S.; Nielsen, M; Ramsey-Musolf, M. J.
1998-01-01
We study contributions to the nucleon strange quark vector current form factors from intermediate states containing K^* mesons. We show how these contributions may be comparable in magnitude to those made by K mesons, using methods complementary to those employed in quark model studies. We also analyze the degree of theoretical uncertainty associated with K^* contributions.
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
Longitudinal-Transverse Separation of Deep-Inelastic Scattering at Low Q² on Nucleons and Nuclei
Energy Technology Data Exchange (ETDEWEB)
Tvaskis, Vladas [Vrije Univ., Amsterdam (Netherlands)
2004-12-06
Since the early experiments at SLAC, which discovered the nucleon substructure and led to the development of the quark parton model, deep inelastic scattering (DIS) has been the most powerful tool to investigate the partonic substructure of the nucleon. After about 30 years of experiments with electron and muon beams the nucleon structure function F_{2}(x,Q^{2}) is known with high precision over about four orders of magnitude in x and Q^{2}. In the region of Q^{2} > 1 (GeV/c)^{2} the results of the DIS measurements are interpreted in terms of partons (quarks and gluons). The theoretical framework is provided in this case by perturbative Quantum Chromo Dynamics (pQCD), which includes scaling violations, as described by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations. The description starts to fail when Q^{2} becomes of the order of 1 (GeV/c)^{2}, where non-perturbative effects (higher-twist effects), which are still not fully understood, become important (non-pQCD). The sensitivity for order-n twist effects increases with decreasing Q^{2}, since they include a factor 1/(Q^{2n}) (n ≥ 1).
International Nuclear Information System (INIS)
The collection contains full texts of 37 contributions; all fall within the INIS Subject Scope. The topics treated include some unsolved problems of nuclear reactions and relevant problems of nuclear structure at low and intermediate energies. (Z.S.)
Moments of F{sub 2} Structure Functions and Multiparton Correlations in Nuclei
Energy Technology Data Exchange (ETDEWEB)
Mikhail Osipenko
2002-10-01
The inclusive inelastic electron scattering o the proton was measured at five different beam energies 1.5, 2.5, 4.0, 4.2 and 4.4 GeV. The data were taken, during February-March 1999, on a liquid hydrogen target with the CLAS detector installed in Hall-B of the Thomas Jefferson National Accelerator Facility (TJNAF). The obtained high statistics and high precision data appear to be in good agreement with previously measured world data and permit to integrate experimental values of F{sub 2} over x at fixed Q{sup 2} , allowing for the first time the evaluation of its experimental moments at low and moderate values of Q{sup 2} . In a combined analysis of CLAS and world data, the Q{sup 2} -evolution of the experimental moments was explored in the range from 0.3 up to 100 GeV{sup 2} . This offered a unique possibility to trace changes of the proton structure function from hard DIS down to the non-perturbative regime through the transition region, which is of particular interest for the TJNAF physics program. The obtained experimental moments allowed to perform a separation between the leading twist, calculable in the framework of the perturbative QCD (pQCD), and higher twists, treated effectively. A comparison with theoretical predictions based either on lattice QCD simulations or obtained within models of the nucleon structure may represent an important test of our understanding of the nucleon structure as observed at large wavelengths.
[Structure and functions of glutathione transferases].
Fedets, O M
2014-01-01
Data about classification, nomenclature, structure, substrate specificity and role of many glutathione transferase's isoenzymes in cell functions have been summarised. The enzyme has been discovered more than 50 years ago. This family of proteins is updated continuously. It has very different composition and will have demand for system analysis for many years.
Progress on nuclear modifications of structure functions
Directory of Open Access Journals (Sweden)
Kumano S.
2016-01-01
Full Text Available We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrinooscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function b1 is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact suggests that a new hadronic phenomenon should exist in the tensor-polarized deuteron at high energies, and it will be experimentally investigated at JLab from the end of 2010’s.
Functional-structural modelling in Gramineae
Fournier, C.; Andrieu, B.; Buck-Sorlin, G.H.; Evers, J.B.; Drouet, D.; Escobar-Gutierriez, A.J.; Vos, J.
2007-01-01
The Gramineae have been a pioneer group among non-woody plants to be modelled with the approach of functional-structural plant modelling (FSPM). During the past decade, models have focussed on morphological aspects of plant development. They now provide crop scientists with general guidelines for bu
Structural Functionalism as a Heuristic Device.
Chilcott, John H.
1998-01-01
Argues that structural functionalism as a method for conducting fieldwork and as a format for the analysis of ethnographic data remains a powerful model, one that is easily understood by professional educators. As a heuristic device, functionalist theory can help in the solution of a problem that is otherwise incapable of theoretical…
Generalized functions, convergence structures, and their applications
Pap, Endre; Pilipović, Stevan; Vladimirov, Vasilij; International Conference "Generalized functions, convergence structures and their applications" (GFCA-87)
1988-01-01
This Proceedings consists of a collection of papers presented at the International Conference "Generalized functions, convergence structures and their applications" held from June 23-27, 1987 in Dubrovnik, Yugoslavia (GFCA-87): 71 participants from 21 countr~es from allover the world took part in the Conference. Proceedings reflects the work of the Conference. Plenary lectures of J. Burzyk, J. F. Colombeau, W. Gahler, H. Keiter, H. Komatsu, B. Stankovic, H. G. Tillman, V. S. Vladimirov provide an up-to-date account of the cur rent state of the subject. All these lectures, except H. G. Tillman's, are published in this volume. The published communications give the contemporary problems and achievements in the theory of generalized functions, in the theory of convergence structures and in their applications, specially in the theory of partial differential equations and in the mathematical physics. New approaches to the theory of generalized functions are presented, moti vated by concrete problems of applicat...
Holographic nucleons in the nuclear medium
Energy Technology Data Exchange (ETDEWEB)
Lee, Bum-Hoon, E-mail: bhl@sogang.ac.kr [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Center for Quantum Spacetime (CQUeST), Sogang University, Seoul 121-742 (Korea, Republic of); Park, Chanyong, E-mail: cyong21@sogang.ac.kr [Center for Quantum Spacetime (CQUeST), Sogang University, Seoul 121-742 (Korea, Republic of)
2015-06-30
We investigate the nucleon's rest mass and dispersion relation in the nuclear medium which is holographically described by the thermal charged AdS geometry. With this background, the chiral condensate plays an important role to determine the nucleon's mass in both the vacuum and the nuclear medium. It also significantly modifies the nucleon's dispersion relation. The nucleon's mass in the high density regime increases with density as expected, while in the low density regime it slightly decreases. We further study the splitting of the nucleon's energies caused by the isospin interaction with the nuclear medium.
Holographic nucleons in the nuclear medium
International Nuclear Information System (INIS)
We investigate the nucleon's rest mass and dispersion relation in the nuclear medium which is holographically described by the thermal charged AdS geometry. With this background, the chiral condensate plays an important role to determine the nucleon's mass in both the vacuum and the nuclear medium. It also significantly modifies the nucleon's dispersion relation. The nucleon's mass in the high density regime increases with density as expected, while in the low density regime it slightly decreases. We further study the splitting of the nucleon's energies caused by the isospin interaction with the nuclear medium
Fusion reactor nucleonics: status and needs
International Nuclear Information System (INIS)
The national fusion technology effort has made a good start at addressing the basic nucleonics issues, but only a start. No fundamental nucleonics issues are seen as insurmountable barriers to the development of commercial fusion power. To date the fusion nucleonics effort has relied almost exclusively on other programs for nuclear data and codes. But as we progress through and beyond ETF type design studies the fusion program will need to support a broad based nucleonics effort including code development, sensitivity studies, integral experiments, data acquisition etc. It is clear that nucleonics issues are extremely important to fusion development and that we have only scratched the surface
Nucleon Emision Off Nuclei Induced By Neutrino Interactions
Valverde, M; Amaro, J E; Vicente-Vacas, M J
2009-01-01
We make a review of the main nuclear effects that affect neutrino-nucleus cross sections. We discuss how the different models in the literature try to describe these different effects, and thus try to compare between them. We focus on the quasi-elastic reaction in the neutrino energy region of around 1 GeV, where recent data from MiniBoone are available. Among the issues discussed are the different treatment of medium corrections to initial and nal state nucleon wave functions and the problem of the rescattering of ejected nucleons.
Nucleon matrix elements using the variational method in lattice QCD
Dragos, Jack; Kamleh, Waseem; Leinweber, Derek B; Nakamura, Yoshifumi; Rakow, Paul E L; Schierholz, Gerrit; Young, Ross D; Zanotti, James M
2016-01-01
The extraction of hadron matrix elements in lattice QCD using the standard two- and three-point correlator functions demands careful attention to systematic uncertainties. One of the most commonly studied sources of systematic error is contamination from excited states. We apply the variational method to calculate the axial vector current $g_{A}$, the scalar current $g_{S}$ and the quark momentum fraction $\\left$ of the nucleon and we compare the results to the more commonly used summation and two-exponential fit methods. The results demonstrate that the variational approach offers a more efficient and robust method for the determination of nucleon matrix elements.
Use of the Husimi distribution for nucleon tomography
Energy Technology Data Exchange (ETDEWEB)
Hagiwara, Yoshikazu [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Hatta, Yoshitaka, E-mail: hatta@yukawa.kyoto-u.ac.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)
2015-08-15
In the context of nucleon structure, the Wigner distribution has been commonly used to visualize the phase-space distribution of quarks and gluons inside the nucleon. However, the Wigner distribution does not allow for a probabilistic interpretation because it takes negative values. In pursuit of a positive phase-space distribution in QCD, we introduce the Husimi distribution and demonstrate its advantages via a simple one-loop example. We also comment on a possible connection to the semiclassical approach to saturation physics at small-x.
Quantal Nucleon Diffusion I: Central Collisions of Symmetric Nuclei
Ayik, S; Yilmaz, B; Umar, A S
2016-01-01
Quantal diffusion mechanism of nucleon exchange is studied in the central collisions of several symmetric heavy-ion collisions in the framework of the Stochastic Mean-Field (SMF) approach. Since at bombarding energies below the fusion barrier, di-nuclear structure is maintained, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Quantal diffusion coefficients, including memory effects, for proton and neutron exchanges are extracted microscopically employing the SMF approach. The quantal calculations of neutron and proton variances are compared with the semi-classical results.
Scalar strangeness content of the nucleon and baryon sigma terms
Ren, Xiu-Lei; Geng, Li-Sheng; Meng, Jie
2014-01-01
The scalar strangeness content of the nucleon, characterized by the so-called strangeness-nucleon sigma term, is of fundamental importance in understanding its sea-quark flavor structure. We report a determination of the octet baryon sigma terms via the Feynman-Hellmann theorem by analyzing the latest high-statistics $n_f=2+1$ lattice QCD simulations with covariant baryon chiral perturbation theory up to next-to-next-to-next-to-leading order. In particular, we predict $\\sigma_{\\pi N}=55(1)(4)...
Path integral formalism for a simple interacting nucleon model
International Nuclear Information System (INIS)
The early onset of the baryon density in QCD simulations can be explained by the high flavour degeneracy when using staggered fermions. A simple interacting nucleon gas model had already shown that the gas condenses at very low chemical potential as in the lattice simulations at four flavours. In order to study more carefully the nucleon gas model in the condensation region we have developed the path integral formalism to treat the first quantization non perturbatively, describing the partition function for the interacting system of nucleons. First Monte Carlo results show good agreement with the lattice QCD simulations for the onset chemical potentials and saturation densities. The extrapolation to nature gives reasonable results. (orig.)
Chiral Symmetry and the Nucleon-Nucleon Interaction
Directory of Open Access Journals (Sweden)
Ruprecht Machleidt
2016-04-01
Full Text Available We review how nuclear forces emerge from low-energy quantum chromodynamics (QCD via chiral effective field theory (EFT. During the past two decades, this approach has evolved into a powerful tool to derive nuclear two- and many-body forces in a systematic and model-independent way. We then focus on the nucleon-nucleon (N N interaction and show in detail how, governed by chiral symmetry, the long- and intermediate-range of the N N potential builds up order by order. We proceed up to sixth order in small momenta, where convergence is achieved. The final result allows for a full assessment of the validity of the chiral EFT approach to the N N interaction.
Open and Hidden Strangeness Production in Nucleon-Nucleon Collisions
Shyam, Radhey
2008-01-01
We present an overview of the description of K and eta meson productions in nucleon-nucleon collisions within an effective Lagrangian model where meson production proceeds via excitation, propagation and subsequent decay of intermediate baryonic resonant states. The $K$ meson contains a strange quark ($s$) or antiquark ($\\bar s$) while the $\\eta$ meson has hidden strangeness as it contains some component of the $s{\\bar s}$ pair. Strange meson production is expected to provide information on the manifestation of quantum chromodynamics in the non-perturbative regime of energies larger than that of the low energy pion physics. We discuss specific examples where proper understanding of the experimental data for these reactions is still lacking.
Parity violation in the nucleon-nucleon interaction
International Nuclear Information System (INIS)
A short review is presented of experiments designed to detect parity nonconservation (PNC) in the interaction between nucleons. A recent measurement of PNC in proton-proton scattering is described, and some of the methods which were developed to reduce systematic errors to less than or equal to 2 x 10-8 are discussed. The results of this experiment and of other measurements on PNC are compared to theoretical predictions
Peripheral Nucleon-Nucleon Phase Shifts and Chiral Symmetry
Kaiser, N; Weise, W
1997-01-01
Within the one-loop approximation of baryon chiral perturbation theory we calculate all one-pion and two-pion exchange contributions to the nucleon-nucleon interaction. In fact we construct the elastic NN-scattering amplitude up to and including third order in small momenta. The phase shifts with orbital angular momentum $L\\geq2 $ and the mixing angles with $J\\geq2$ are given parameterfree and thus allow for a detailed test of chiral symmetry in the two-nucleon system. We find that for the D-waves the $2\\pi$-exchange corrections are too large as compared with empirical phase shifts, signaling the increasing importance of shorter range effects in lower partial waves. For higher partial waves, especially for G-waves, the model independent $2\\pi$-exchange corrections bring the chiral prediction close to empirical NN phase shifts. We propose to use the chiral NN phase shifts with $L\\geq 3$ as input in a future phase shift analysis. Furthermore, we compute the irreducible two-pion exchange NN-potentials in coordin...
Form factors in an algebraic model of the nucleon
Bijker, R
1995-01-01
We study the electromagnetic form factors of the nucleon in a collective model of baryons. In an algebraic approach to hadron structure, we derive closed expressions for both elastic and transition form factors, and consequently for the helicity amplitudes that can be measured in electro- and photoproduction.
Structure and function of mitochondrial complex I.
Wirth, Christophe; Brandt, Ulrich; Hunte, Carola; Zickermann, Volker
2016-07-01
Proton-pumping NADH:ubiquinone oxidoreductase (complex I) is the largest and most complicated enzyme of the respiratory chain. Fourteen central subunits represent the minimal form of complex I and can be assigned to functional modules for NADH oxidation, ubiquinone reduction, and proton pumping. In addition, the mitochondrial enzyme comprises some 30 accessory subunits surrounding the central subunits that are not directly associated with energy conservation. Complex I is known to release deleterious oxygen radicals (ROS) and its dysfunction has been linked to a number of hereditary and degenerative diseases. We here review recent progress in structure determination, and in understanding the role of accessory subunits and functional analysis of mitochondrial complex I. For the central subunits, structures provide insight into the arrangement of functional modules including the substrate binding sites, redox-centers and putative proton channels and pump sites. Only for two of the accessory subunits, detailed structures are available. Nevertheless, many of them could be localized in the overall structure of complex I, but most of these assignments have to be considered tentative. Strikingly, redox reactions and proton pumping machinery are spatially completely separated and the site of reduction for the hydrophobic substrate ubiquinone is found deeply buried in the hydrophilic domain of the complex. The X-ray structure of complex I from Yarrowia lipolytica provides clues supporting the previously proposed two-state stabilization change mechanism, in which ubiquinone redox chemistry induces conformational states and thereby drives proton pumping. The same structural rearrangements may explain the active/deactive transition of complex I implying an integrated mechanistic model for energy conversion and regulation. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26921811
Third-order QCD corrections to the charged-current structure function F{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Vermaseren, J.A.M. [NIKHEF, Amsterdam (Netherlands); Vogt, A. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences
2008-12-15
We compute the coefficient function for the charge-averaged W{sup {+-}}-exchange structure function F{sub 3} in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling {alpha}{sub s} and of 1/Q{sup 2} power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F{sub 3} in powers of {alpha}{sub s} is stable at all values of x relevant to measurements at high scales Q{sup 2}. At small x the third-order coefficient function is dominated by diagrams with the colour structure d{sup abc}d{sub abc} not present at lower orders. At large x the coefficient function for F{sub 3} is identical to that of F{sub 1} up to terms vanishing for x{yields}1. (orig.)
International Nuclear Information System (INIS)
We address the typical strengths of hadronic parity-violating three-nucleon interactions in ''pion-less'' Effective Field Theory (EFT) in the nucleon-deuteron (iso-doublet) system. By analysing the superficial degree of divergence of loop diagrams, we conclude that no such interactions are needed at leading order, O(εQ-1). The only two distinct parity-violating three-nucleon structures with one derivative mix 2S(1)/(2) and 2P(1)/(2) waves with iso-spin transitions Δ I = 0 or 1. Due to their structure, they cannot absorb any divergence ostensibly appearing at next-to-leading order, O(εQ0). This observation is based on the approximate realisation of Wigner's combined SU(4) spin-isospin symmetry in the two-nucleon system, even when effective-range corrections are included. Parity-violating three-nucleon interactions thus only appear beyond next-to-leading order. This guarantees renormalisability of the theory to that order without introducing new, unknown coupling constants and allows the direct extraction of parity-violating two-nucleon interactions from three-nucleon experiments. (orig.)
NAC transcription factors: structurally distinct, functionally diverse
DEFF Research Database (Denmark)
Olsen, Addie Nina; Ernst, Heidi A; Leggio, Leila Lo;
2005-01-01
NAC proteins constitute one of the largest families of plant-specific transcription factors, and the family is present in a wide range of land plants. Here, we summarize the biological and molecular functions of the NAC family, paying particular attention to the intricate regulation of NAC protein...... level and localization, and to the first indications of NAC participation in transcription factor networks. The recent determination of the DNA and protein binding NAC domain structure offers insight into the molecular functions of the protein family. Research into NAC transcription factors has...
Longitudinal Structure Function FL from Charm Structure Function F2c
Institute of Scientific and Technical Information of China (English)
B.Rezaei; G.R.Boroun
2013-01-01
We predict the effect of the charm structure function on the longitudinal structure function at small x.In NLO analysis we find that the hard Pomeron behavior gives a good description of FL and Fkc (k =2,L) at small x values.We conclude that a direct relation between FL∝ F2c would provide useful information on how to measure longitudinal structure function at high Q2 values.Having checked that this model gives a good description of the data,when compared with other models.
Proteins with Novel Structure, Function and Dynamics
Pohorille, Andrew
2014-01-01
Recently, a small enzyme that ligates two RNA fragments with the rate of 10(exp 6) above background was evolved in vitro (Seelig and Szostak, Nature 448:828-831, 2007). This enzyme does not resemble any contemporary protein (Chao et al., Nature Chem. Biol. 9:81-83, 2013). It consists of a dynamic, catalytic loop, a small, rigid core containing two zinc ions coordinated by neighboring amino acids, and two highly flexible tails that might be unimportant for protein function. In contrast to other proteins, this enzyme does not contain ordered secondary structure elements, such as alpha-helix or beta-sheet. The loop is kept together by just two interactions of a charged residue and a histidine with a zinc ion, which they coordinate on the opposite side of the loop. Such structure appears to be very fragile. Surprisingly, computer simulations indicate otherwise. As the coordinating, charged residue is mutated to alanine, another, nearby charged residue takes its place, thus keeping the structure nearly intact. If this residue is also substituted by alanine a salt bridge involving two other, charged residues on the opposite sides of the loop keeps the loop in place. These adjustments are facilitated by high flexibility of the protein. Computational predictions have been confirmed experimentally, as both mutants retain full activity and overall structure. These results challenge our notions about what is required for protein activity and about the relationship between protein dynamics, stability and robustness. We hypothesize that small, highly dynamic proteins could be both active and fault tolerant in ways that many other proteins are not, i.e. they can adjust to retain their structure and activity even if subjected to mutations in structurally critical regions. This opens the doors for designing proteins with novel functions, structures and dynamics that have not been yet considered.
Flavor asymmetry of the nucleon
Bijker, R
2008-01-01
The flavor asymmetry of the nucleon sea is discussed in an unquenched quark model for baryons in which the effects of quark-antiquark pairs (u anti-u, d anti-d and s anti-s) are taken into account in an explicit form. The inclusion of q anti-q pairs leads automatically to an excess of anti-d over anti-u quarks in the proton, in agreement with experimental data.
Structure and function of endothelial caveolae.
Stan, Radu-Virgil
2002-06-01
Caveolae are spherical invaginations of the plasma membrane and associated vesicles that are found at high surface densities in most cells, endothelia included. Their structural framework has been shown to consist of oligomerized caveolin molecules interacting with cholesterol and sphingolipids. Caveolae have been involved in many cellular functions such as endocytosis, signal transduction, mechano-transduction, potocytosis, and cholesterol trafficking. Some confusion still persists in the field with respect to the relationship between caveolae and the lipid rafts, which have been involved in many of the above functions. In addition to all these, endothelial caveolae have been involved in capillary permeability by their participation in the process of transcytosis. This short review will focus on their structure and components, methods used to determine these components, and the role of caveolae in the transendothelial exchanges between blood plasma and the interstitial fluid. PMID:12112442
MRI in Optic Neuritis: Structure, Function, Interactions
DEFF Research Database (Denmark)
Fuglø, Dan
2011-01-01
Optic neuritis (ON) is an acute inflammatory demyelinating condition of the optic nerve characterised by transient visual loss and eye pain. ON is the presenting symptom in 20% of patients with multiple sclerosis (MS) and the 15 year risk of developing MS after ON is about 50%. Decline in vision...... resonance imaging (MRI), and the visual evoked potential (VEP) continues to show a delayed P100 indicating persistent demyelination. The explanation for this apparent discrepancy between structure and function could be due to either a redundancy in the visual pathways so that some degree of signal loss...... will have very few or no clinical symptoms, or it could be due to compensatory mechanisms in the visual pathway or the visual cortex. In order to understand the pathophysiology and recovery processes in ON it is essential to have sensitive methods to asses both structure and function. These methods...
Phosphatidylinositol 4-kinases: Function, structure, and inhibition
International Nuclear Information System (INIS)
The phosphatidylinositol 4-kinases (PI4Ks) synthesize phosphatidylinositol 4-phosphate (PI4P), a key member of the phosphoinositide family. PI4P defines the membranes of Golgi and trans-Golgi network (TGN) and regulates trafficking to and from the Golgi. Humans have two type II PI4Ks (α and β) and two type III enzymes (α and β). Recently, the crystal structures were solved for both type II and type III kinase revealing atomic details of their function. Importantly, the type III PI4Ks are hijacked by +RNA viruses to create so-called membranous web, an extensively phosphorylated and modified membrane system dedicated to their replication. Therefore, selective and potent inhibitors of PI4Ks have been developed as potential antiviral agents. Here we focus on the structure and function of PI4Ks and their potential in human medicine
Phosphatidylinositol 4-kinases: Function, structure, and inhibition
Energy Technology Data Exchange (ETDEWEB)
Boura, Evzen, E-mail: boura@uochb.cas.cz; Nencka, Radim, E-mail: nencka@uochb.cas.cz
2015-10-01
The phosphatidylinositol 4-kinases (PI4Ks) synthesize phosphatidylinositol 4-phosphate (PI4P), a key member of the phosphoinositide family. PI4P defines the membranes of Golgi and trans-Golgi network (TGN) and regulates trafficking to and from the Golgi. Humans have two type II PI4Ks (α and β) and two type III enzymes (α and β). Recently, the crystal structures were solved for both type II and type III kinase revealing atomic details of their function. Importantly, the type III PI4Ks are hijacked by +RNA viruses to create so-called membranous web, an extensively phosphorylated and modified membrane system dedicated to their replication. Therefore, selective and potent inhibitors of PI4Ks have been developed as potential antiviral agents. Here we focus on the structure and function of PI4Ks and their potential in human medicine.
Structure function calculations for Ostwald Ripening processes
Hassan, Razi A.
1990-01-01
A program for computing the structure function for configurations involved in Ostwald Ripening was written. The basic algorithms are derived from a mathematical analysis of a two-dimensional model system developed by Bortz, et. al. (1974). While it is expected that the values form the computer simulations will reflect Ostwald Ripening, at this point the program is still being tested. Some preliminary runs seem to justify the expectations.
Increased Functionality Porous Optical Fiber Structures
Wooddell, Michael Gary
2007-01-01
A novel fiber optic structure, termed stochastic ordered hole fibers, has been developed that contains an ordered array of six hollow tubes surrounding a hollow core, combined with a nanoporous glass creating a unique fully three dimensional pore/fiber configuration. The objective of this study is to increase the functionality of these stochastic ordered hole fibers, as well as porous clad fibers, by integrating electronic device components such as conductors, and semiconductor...
Structural and functional neuroimaging in intractable epilepsy
Chinchure Swati; Kesavadas Chandrasekharan; Thomas Bejoy
2010-01-01
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 res...
Structure, function, and plasticity of GABA transporters
Annalisa eScimemi
2014-01-01
GABA transporters belong to a large family of neurotransmitter:sodium symporters. They are widely expressed throughout the brain, with different levels of expression in different brain regions. GABA transporters are present in neurons and in astrocytes and their activity is crucial to regulate the extracellular concentration of GABA under basal conditions and during ongoing synaptic events. Numerous efforts have been devoted to determine the structural and functional properties of GABA transp...
Functional-structural modelling in Gramineae
C. Fournier; Andrieu, B.; Buck-Sorlin, G.H.; Evers, J.B.; Drouet, D.; Escobar-Gutierriez, A.J.; VOS, J
2007-01-01
The Gramineae have been a pioneer group among non-woody plants to be modelled with the approach of functional-structural plant modelling (FSPM). During the past decade, models have focussed on morphological aspects of plant development. They now provide crop scientists with general guidelines for building new cereal models. We present some of them here, considering the different aspects of cereal architectural modelling: plant development, pattern formation and plant geometry. We also review ...
Tonjes, M B
2002-01-01
Relativistic heavy ion physics is the study of nuclear matter interacting at high energies and densities. The collisions of gold nuclei at the Relativistic Heavy Ion Collider (RHIC) provide a source of high density matter for the study and creation of a novel state of matter, the Quark-Gluon Plasma (QGP). The data set studied in this dissertation is taken from Au+Au interactions at a center of mass energy of 130 GeV, measured in summer 2000. This is the first such data produced at RHIC. The analysis presented here focuses upon the measurement of balance functions, which are new observables in the field of heavy ion physics. The balance function for heavy ion physics is introduced in Bass, Danielewicz, and Pratt, Phys. Rev. Lett. 85, 2689 (2000). The data were taken with the STAR (Solenoidal Tracker At RHIC) detector, with analysis performed on charged particles in a pseudorapidity region of |η| < 1.3. The balance function measured for conserving charge/anti- charge pion pairs as a function of r...
Medium Influence of the Nucleon-Nucleon Cross Section on the Fragmentation
Institute of Scientific and Technical Information of China (English)
刘建业; 邢永忠; 郭文军
2003-01-01
Based on an isospin-dependent quantum molecular dynamics model we studied the influence of a medium correction of an isospin-dependent nucleon-nucleon cross section on the fragmentation at the intermediate energy heavy-ion collisions. We found that the medium correction from an isospin-dependent nucleon-nucleon cross section increases the dependence of the fragmentation on the isospin effect of in-medium nucleon-nucleon cross section, at the same time, the momentum-dependent interaction also produces an important role for enhancing the influence of the medium correction on the isospin effect of two-body collisions in the fragmentation process.
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.
Soma, V; Duguet, T
2013-01-01
The newly developed Gorkov-Green's function approach represents a promising path to the ab initio description of medium-mass open-shell nuclei. We discuss the implementation of the method at second order with a two-body interaction, with particular attention to the numerical solution of Gorkov's equation. Different sources of theoretical error and degrees of self-consistency are investigated. We show that Krylov projection techniques with a multi-pivot Lanczos algorithm efficiently handle the growth of poles in the one-body Green's function when Gorkov's equation is solved self-consistently. The end result is a tractable, accurate and gently scaling ab initio scheme applicable to full isotopic chains in the medium-mass region.
Soma, V.; Duguet, T.; Barbieri, C.(Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom)
2011-01-01
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 semi-magic 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) secon...
Can the 4He experiments serve as a database for determining the three-nucleon force?
Hofmann, H M; Hale, Gerald M.; Hofmann, Hartmut M.
2005-01-01
We report on microscopic calculations for the 4He compound system in the framework of the resonating group model employing realistic nucleon-nucleon and three nucleon forces. The resulting scattering phase shifts are compared to those of a comprehensive R-matrix analysis of all data in this system, which are available in numerical form. The agreement between calculation and analysis is in most cases very good. Adding three-nucleon forces yields in many cases large effects. For a few cases the new agreement is striking. We relate some differencies between calculation and analysis to specific data and discuss neccessary experiments to clarify the situation. From the results we conclude that the data of the 4He system might be well suited to determine the structure of the three-nucleon force.
General aspects of the nucleon-nucleon interaction and nuclear matter properties
Energy Technology Data Exchange (ETDEWEB)
Plohl, Oliver
2008-07-25
The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are
Exploring Three-Nucleon Forces in Lattice QCD
Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji
2011-01-01
Three-nucleon forces (3NF) are investigated from two-flavor lattice QCD simulations. We utilize the Nambu-Bethe-Salpeter (NBS) wave function to determine two-nucleon forces (2NF) and 3NF in the same framework. As a first exploratory study, we extract 3NF through three nucleons aligned linearly with an equal spacing. This is the simplest geometrical configuration which reduces the huge computational cost of calculating the NBS wave function. Quantum numbers of the three-nucleon system are chosen to be (I, J^P)=(1/2,1/2^+) (the triton channel). Lattice QCD simulations are performed using N_f=2 dynamical clover fermion configurations at the lattice spacing of a = 0.156 fm on a 16^3 x 32 lattice with a large quark mass corresponding to m_\\pi= 1.13 GeV. We find repulsive 3NF at short distance in the triton channel. Several sources of systematic errors are also discussed.
The structure and function of presynaptic endosomes
Energy Technology Data Exchange (ETDEWEB)
Jähne, Sebastian, E-mail: sebastian.jaehne1@stud.uni-goettingen.de [Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Humboldtallee 23, 37073 Göttingen (Germany); International Max Planck Research School for Neurosciences, 37077 Göttingen (Germany); Rizzoli, Silvio O. [Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Humboldtallee 23, 37073 Göttingen (Germany); Helm, Martin S., E-mail: martin.helm@med.uni-goettingen.de [Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Humboldtallee 23, 37073 Göttingen (Germany); International Max Planck Research School for Molecular Biology, 37077 Göttingen (Germany)
2015-07-15
The function of endosomes and of endosome-like structures in the presynaptic compartment is still controversial. This is in part due to the absence of a consensus on definitions and markers for these compartments. Synaptic endosomes are sometimes seen as stable organelles, permanently present in the synapse. Alternatively, they are seen as short-lived intermediates in synaptic vesicle recycling, arising from the endocytosis of large vesicles from the plasma membrane, or from homotypic fusion of small vesicles. In addition, the potential function of the endosome is largely unknown in the synapse. Some groups have proposed that the endosome is involved in the sorting of synaptic vesicle proteins, albeit others have produced data that deny this possibility. In this review, we present the existing evidence for synaptic endosomes, we discuss their potential functions, and we highlight frequent technical pitfalls in the analysis of this elusive compartment. We also sketch a roadmap to definitely determine the role of synaptic endosomes for the synaptic vesicle cycle. Finally, we propose a common definition of synaptic endosome-like structures.
The structure and function of presynaptic endosomes
International Nuclear Information System (INIS)
The function of endosomes and of endosome-like structures in the presynaptic compartment is still controversial. This is in part due to the absence of a consensus on definitions and markers for these compartments. Synaptic endosomes are sometimes seen as stable organelles, permanently present in the synapse. Alternatively, they are seen as short-lived intermediates in synaptic vesicle recycling, arising from the endocytosis of large vesicles from the plasma membrane, or from homotypic fusion of small vesicles. In addition, the potential function of the endosome is largely unknown in the synapse. Some groups have proposed that the endosome is involved in the sorting of synaptic vesicle proteins, albeit others have produced data that deny this possibility. In this review, we present the existing evidence for synaptic endosomes, we discuss their potential functions, and we highlight frequent technical pitfalls in the analysis of this elusive compartment. We also sketch a roadmap to definitely determine the role of synaptic endosomes for the synaptic vesicle cycle. Finally, we propose a common definition of synaptic endosome-like structures
Phenylalanine hydroxylase: function, structure, and regulation.
Flydal, Marte I; Martinez, Aurora
2013-04-01
Mammalian phenylalanine hydroxylase (PAH) catalyzes the rate-limiting step in the phenylalanine catabolism, consuming about 75% of the phenylalanine input from the diet and protein catabolism under physiological conditions. In humans, mutations in the PAH gene lead to phenylketonuria (PKU), and most mutations are mainly associated with PAH misfolding and instability. The established treatment for PKU is a phenylalanine-restricted diet and, recently, supplementation with preparations of the natural tetrahydrobiopterin cofactor also shows effectiveness for some patients. Since 1997 there has been a significant increase in the understanding of the structure, catalytic mechanism, and regulation of PAH by its substrate and cofactor, in addition to improved correlations between genotype and phenotype in PKU. Importantly, there has also been an increased number of studies on the structure and function of PAH from bacteria and lower eukaryote organisms, revealing an additional anabolic role of the enzyme in the synthesis of melanin-like pigments. In this review, we discuss these recent studies, which contribute to define the evolutionary adaptation of the PAH structure and function leading to sophisticated regulation for effective catabolic processing of phenylalanine in mammalian organisms.
Nucleon Resonances in Meson Nucleon Scattering with Strangeness Production
Waluyo, A.; Bennhold, C.; Haberzettl, H.; Penner, G.; Mosel, U.; Mart, T.
2000-01-01
An effective Lagrangian model in a coupled channels framework is applied to extract nucleon resonance parameters. In the K-matrix approximation, we simultaneously analyze all the available data for the transitions from pi N to five possible meson-baryon final states, pi N, pipi N, eta N, K Lambda, and KSigma, in the energy range from pi N threshold up to W = 2 GeV. In this work, we focus our efforts on the K Sigma channel. In particular, we include a set of Delta resonances around 1900 MeV: t...
Pion production in nucleon-nucleon collisions at low energies
Energy Technology Data Exchange (ETDEWEB)
Baru, Vadim [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Epelbaum, Evgeny [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Filin, Arseniy [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Haidenbauer, Johann; Hanhart, Christoph [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany); Kudryavtsev, Alexander [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Lensky, Vadim [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); European Centre for Theoretical Studies in Nuclear Physics and Related Areas, Villazzano (Trento) (Italy); Meissner, Ulf G. [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany)
2010-07-01
With the advent of chiral perturbation theory, the low-energy effective field theory of QCD, high accuracy calculations for hadronic reactions with a controlled error estimation have become possible. We survey the recent developments in the reaction NN{yields}NN{pi} in chiral EFT. We argue that the counting scheme that acknowledges the large momentum transfer between the initial and the final nucleons allows for a consistent description of s- and p-wave pion production. The status of the theory for pion production in the isospin conserving case allows us to challenge charge symmetry breaking effects recently observed experimentally in pn{yields}d{pi}{sup 0}.
STRUCTURE AND GRAMMATICAL FUNCTION OF LEO LANGUAGE
Directory of Open Access Journals (Sweden)
I Ketut Yudha
2015-01-01
Full Text Available Lio language is a language spoken in Central Flores. Having limited morphological process in general and affixation process involving verbs (head marking and nouns (dependent marking in particular, it is classified into an isolating language. The studies exploring the languages spoken in the eastern part of Indonesia using Lexical Functional Grammar and the theory of typology are highly limited. In addition, Lio language is merely an isolating one and does not have cross referencing. It is this which inspired the writer to conduct research in syntax. This study aims at investigating the canonic structure, the types of verbs used as predicates, the grammatical function, the alternate of clausal structure, the mapping and the pivotance in Lio language. The results of analysis show that the clauses in Lio language can be divided into basic clauses with verbal and nonverbal predicates. The predicates of the verbal clauses are classified into simple, serial, and causative. The serial verbal constructions are distinguished based on the semantic features of the verbal components forming the serial verbal constructions. These types can be observed from the nature of the relationships among the components forming the serial verbal constructions. A serial verbal construction is made up of more than one verbs and behaves as a simple predicate. There is no dependence marker among the components forming the serial verb. The causative structure also forms monoclause and biclause. The functional mapping uses the features [+/-r] and [+/-o], the argument uses the features [-r] and [-o] which are mapped to SUBJ, [-r] and [+o] are mapped to OBJ, [+r] and [+o] are mapped to OBJ2 or OBJ? and [+r] and [-o] are mapped to OBL (Oblique. Lio language has GF SUBJ and OBJ as the nuclear GF (nuclear grammatical function, and OBL, COMP, and ADJ as the nonnuclear grammatical functions. The SUBJ appears before the verb (preverbal position and the OBJ appears after the
Gupta, S; Musthafa, M M; Bhardwaj, H D; Prasadl, R
2000-01-01
This experiment has been done with a view to studying complete and incomplete fusion in heavy-ion-induced reactions. Excitation functions for several reactions induced by /sup 12/C/sup 5+/ ions on /sup 165/Ho at incident energies from 55 to 80 MeV have been measured using the activation technique. The analysis of the data has been done using the codes ALICE-91 and CASCADE. The parameter F/sub theta /, the ratio of actual moment of inertia to the rigid-body value, has been found to play an important role in the calculations done by the code CASCADE. Significant contributions from both the complete and the incomplete fusion channels have been observed. Further, in the case of the reaction (C, p3n) considerable contribution from the decay of higher charge isobar precursor has been observed. (23 refs).
Database of Nucleon-Nucleon Scattering Cross Sections by Stochastic Simulation Project
National Aeronautics and Space Administration — A database of nucleon-nucleon elastic differential and total cross sections will be generated by stochastic simulation of the quantum Liouville equation in the...
Chiral dynamics in few-nucleon systems
Epelbaum, E; Glöckle, W; Elster, C; Kamada, H; Nogga, A; Witala, H; Epelbaum, Evgeny; Mei{\\ss}ner, Ulf-G.; Gl\\"ockle, Walter
2001-01-01
We report on recent progress achieved in calculating various few-nucleon low-energy observables from effective field theory. Our discussion includes scattering and bound states in the 2N, 3N and 4N systems and isospin violating effects in the 2N system. We also establish a link between the nucleon-nucleon potential derived in chiral effective field theory and various modern high-precision potentials.
Dissecting nucleon transition electromagnetic form factors
Segovia, Jorge
2016-01-01
In Poincar\\'e-covariant continuum treatments of the three valence-quark bound-state problem, the force behind dynamical chiral symmetry breaking also generates nonpointlike, interacting diquark correlations in the nucleon and its resonances. We detail the impact of these correlations on the electromagnetically-induced nucleon-$\\Delta$ and nucleon-Roper transitions, providing a flavour-separation of the latter and associated predictions that can be tested at modern facilities.
Gluon Contribution To The Nucleon Spin
Arash, Firooz; Taghavi-Shahri, Fatemeh; Shahveh, Abolfazl
2011-07-01
Gluon polarization in Nucleon is evaluated in the valon representation of hadrons. It is shown that although δg/g is small at the currently measured kinematics, it does not imply that the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δg(Q2), is sizable. We also notice that the majority of Δg is concentrated at around x = 0.08.
Gluon Contribution To The Nucleon Spin
International Nuclear Information System (INIS)
Gluon polarization in Nucleon is evaluated in the valon representation of hadrons. It is shown that although δg/g is small at the currently measured kinematics, it does not imply that the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δg(Q2), is sizable. We also notice that the majority of Δg is concentrated at around x = 0.08.
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
Proton structure function at small Q^2
Donnachie, A; Landshoff, P V
1993-01-01
A fit is made to the data for the proton structure function up to Q^2=10 GeV^2, including the real gamma p total cross-section. It is economical and simple, and its form is motivated by physical principles. It is extrapolated down to very small values of x. Data for the ratio (nu W_2^n/nu W_2^p) are also fitted. A FORTRAN program for the fit to (nu W_2^p) is available by email on request Figure 5 from the original version has been deleted.
Three-nucleon forces in exotic open-shell isotopes
Soma, V; Cipollone, A; Duguet, T; Navratil, P
2013-01-01
Advances in the self-consistent Green's function approach to finite nuclei are discussed, including the implementation of three-nucleon forces and the extension to the Gorkov formalism. We report results on binding energies in the nitrogen and fluorine isotopic chains, as well as spectral functions of 22O. The application to medium-mass open-shell systems is illustrated by separation energy spectra of two argon isotopes, which are compared to one-neutron removal experiments.
Dispersion relations and the spin polarizabilities of the nucleon
Drechsel, D; Hanstein, O
1998-01-01
A forward dispersion calculation is implemented for the spin polarizabilities are related to the spin structure of the nucleon at low energies and are structure-constants of the Compton scattering amplitude at ${\\cal O}(\\omega^3)$. In the absence of a direct experimental measurement of these quantities, a dispersion calculation serves the purpose of constraining the model building, and of comparing with recent calculations in heavy baryon chiral perturbation theory.
Strange chiral nucleon form factors
Hemmert, T R; Meißner, Ulf G; Hemmert, Thomas R.; Kubis, Bastian; Meissner, Ulf-G.
1999-01-01
We investigate the strange electric and magnetic form factors of the nucleon in the framework of heavy baryon chiral perturbation theory to third order in the chiral expansion. All counterterms can be fixed from data. In particular, the two unknown singlet couplings can be deduced from the parity-violating electron scattering experiments performed by the SAMPLE and the HAPPEX collaborations. Within the given uncertainties, our analysis leads to a small and positive electric strangeness radius, $ = (0.05 \\pm 0.16) fm^2$. We also deduce the consequences for the upcoming MAMI A4 experiment.
Light-cone structure of vertex functions for composite fields
Ciafaloni, Marcello
1973-01-01
Vertex functions for composite fields are defined in a model field theory both on and off mass shell. Light-cone dominance at large momentum transfer is shown to hold, by the compositeness assumption, for the off-shell vertex function. On the other hand, it is in general untrue that the elastic form factor probes light-like distances between the constituents inside the nucleon. The relevant light-cone singularity (in the relative space-time separation x) is less important in this case than the large x/sub 0/ behaviour of the wave function at fixed x/sup 2/. It is found however that, under some conditions, the light-cone singularity determines the large x/sub 0/ behaviour of the wave function, and therefore the large q/sup 2/ behaviour of the form factor. A relation similar to that of Drell-Yan- West is finally established between the asymptotic behaviour of the elastic form factor and the threshold behaviour of the absorptive part of the vertex scaling function. (21 refs).
Models of protocellular structures, functions and evolution
Pohorille, Andrew; New, Michael H.; DeVincenzi, Donald L. (Technical Monitor)
2000-01-01
The central step in the origin of life was the emergence of organized structures from organic molecules available on the early earth. These predecessors to modern cells, called 'proto-cells,' were simple, membrane bounded structures able to maintain themselves, grow, divide, and evolve. Since there is no fossil record of these earliest of life forms, it is a scientific challenge to discover plausible mechanisms for how these entities formed and functioned. To meet this challenge, it is essential to create laboratory models of protocells that capture the main attributes associated with living systems, while remaining consistent with known, or inferred, protobiological conditions. This report provides an overview of a project which has focused on protocellular metabolism and the coupling of metabolism to energy transduction. We have assumed that the emergence of systems endowed with genomes and capable of Darwinian evolution was preceded by a pre-genomic phase, in which protocells functioned and evolved using mostly proteins, without self-replicating nucleic acids such as RNA.
International Nuclear Information System (INIS)
We study the low x behavior of non-singlet spin structure Function, of the nucleon in the so-called the valon representation. We find the double logarithmic term Ln2(1/x) in the polarized non singlet structure function at small x with using the valon model .The Structure of the valon itself develops through the perturbative dressing of a valence quark in QCD, which is independent of the hosting hadron. The results of non-singlet spin structure Function is in excellent agreement with the experimental data from HERMES collaborations for the entire measured range of x. It also provides an acceptable agreement with the older data from SMC, E143 and E155 experiments. We have further compared our results with those from AA, BB, GRSV, and DNS global fits. (authors)
Structure and Function of KH Domains
Energy Technology Data Exchange (ETDEWEB)
Valverde, R.; Regan, E
2008-01-01
The hnRNP K homology (KH) domain was first identified in the protein human heterogeneous nuclear ribonucleoprotein K (hnRNP K) 14 years ago. Since then, KH domains have been identified as nucleic acid recognition motifs in proteins that perform a wide range of cellular functions. KH domains bind RNA or ssDNA, and are found in proteins associated with transcriptional and translational regulation, along with other cellular processes. Several diseases, e.g. fragile X mental retardation syndrome and paraneoplastic disease, are associated with the loss of function of a particular KH domain. Here we discuss the progress made towards understanding both general and specific features of the molecular recognition of nucleic acids by KH domains. The typical binding surface of KH domains is a cleft that is versatile but that can typically accommodate only four unpaired bases. Van der Waals forces and hydrophobic interactions and, to a lesser extent, electrostatic interactions, contribute to the nucleic acid binding affinity. 'Augmented' KH domains or multiple copies of KH domains within a protein are two strategies that are used to achieve greater affinity and specificity of nucleic acid binding. Isolated KH domains have been seen to crystallize as monomers, dimers and tetramers, but no published data support the formation of noncovalent higher-order oligomers by KH domains in solution. Much attention has been given in the literature to a conserved hydrophobic residue (typically Ile or Leu) that is present in most KH domains. The interest derives from the observation that an individual with this Ile mutated to Asn, in the KH2 domain of fragile X mental retardation protein, exhibits a particularly severe form of the syndrome. The structural effects of this mutation in the fragile X mental retardation protein KH2 domain have recently been reported. We discuss the use of analogous point mutations at this position in other KH domains to dissect both structure and
Melanocortin 1 Receptor: Structure, Function, and Regulation
Wolf Horrell, Erin M.; Boulanger, Mary C.; D’Orazio, John A.
2016-01-01
The melanocortin 1 receptor (MC1R) is a melanocytic Gs protein coupled receptor that regulates skin pigmentation, UV responses, and melanoma risk. It is a highly polymorphic gene, and loss of function correlates with a fair, UV-sensitive, and melanoma-prone phenotype due to defective epidermal melanization and sub-optimal DNA repair. MC1R signaling, achieved through adenylyl cyclase activation and generation of the second messenger cAMP, is hormonally controlled by the positive agonist melanocortin, the negative agonist agouti signaling protein, and the neutral antagonist β-defensin 3. Activation of cAMP signaling up-regulates melanin production and deposition in the epidermis which functions to limit UV penetration into the skin and enhances nucleotide excision repair (NER), the genomic stability pathway responsible for clearing UV photolesions from DNA to avoid mutagenesis. Herein we review MC1R structure and function and summarize our laboratory’s findings on the molecular mechanisms by which MC1R signaling impacts NER. PMID:27303435
Melanocortin 1 Receptor: Structure, Function and Regulation
Directory of Open Access Journals (Sweden)
Erin Marissa Wolf Horrell
2016-05-01
Full Text Available The melanocortin 1 receptor (MC1R is a melanocytic Gs protein coupled receptor that regulates skin pigmentation, UV responses, and melanoma risk. It is a highly polymorphic gene, and loss of function correlates with a fair, UV-sensitive, and melanoma-prone phenotype due to defective epidermal melanization and sub-optimal DNA repair. MC1R signaling, achieved through adenylyl cyclase activation and generation of the second messenger cAMP, is hormonally controlled by the positive agonist melanocortin, the negative agonist agouti signaling protein, and the neutral antagonist β-defensin 3. Activation of cAMP signaling up-regulates melanin production and deposition in the epidermis which functions to limit UV penetration into the skin and enhances nucleotide excision repair, the genomic stability pathway responsible for clearing UV photolesions from DNA to avoid mutagenesis. Herein we review MC1R structure and function and summarize our laboratory’s findings on the molecular mechanisms by which MC1R signaling impacts nucleotide excision repair.
Complex Analyses of Plankton Structure and Function
Directory of Open Access Journals (Sweden)
Karl E. Havens
2001-01-01
Full Text Available This paper critically evaluates some complex methods that have been used to characterize the structure and function of freshwater plankton communities. The focus is on methods related to plankton size structure and carbon transfer. The specific methods reviewed are 1 size spectrum analysis, 2 size-fractionated phytoplankton productivity, 3 size-fractionated zooplankton grazing, 4 plankton ecological transfer efficiency, and 5 grazer effects on phytoplankton community structure. Taken together, these methods can provide information on community ecological properties that are directly related to practical issues including water quality and fisheries productivity. However, caution is warranted since application without a complete understanding of assumptions and context of the manipulations could lead to erroneous conclusions. As an example, experimental studies involving the addition or removal of zooplankton, especially when coupled with nutrient addition treatments, could provide information on the degree of consumer vs. resource control of phytoplankton. Resource managers subsequently could use this information in developing effective measures for controlling nuisance algal biomass. However, the experiments must be done critically and with sufficient safeguards and other measurements to ensure that treatments (e.g., zooplankton exclosure by screening of water actually are successful and do not introduce other changes in the community (e.g., removal of large algae. In all of the methods described here, the investigator must take care when generalizing results and, in particular, carry out a sufficient number of replications to encompass both the major seasonal and spatial variation that occurs in the ecosystem.
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.
Medium Modification of Nucleon Properties in Skyrme Model
Khanna, F.; Rakhimov, A. M.; Musakhanov, M. M.; U. T. Yakhshiev(National University of Uzbekistan)
1996-01-01
A Skyrme type Lagrangian for a skyrmion imbedded in a baryon rich environment is proposed. The dependence of static nucleon properties and nucleon - nucleon tensor interaction on nuclear density is investigated.
Deuteron structure functions in the context of few-body physics
International Nuclear Information System (INIS)
Few-body systems offer a unique challenge to those interested in deep-inelastic scattering. Using the deuteron as the simplest and most easily solvable nuclear system we review the main physics issues in the valence and sea quark regimes. For the former the key issue is the understanding of Fermi motion and binding corrections, and our ability to extract the ratio F2n/F2p as x→1. The most recent analysis of deuteron data for F2n/F2p is consistent with perturbative QCD, but inconsistent with the assumptions common to all standard parton distribution fits. This should be taken into account in calculating event rates at HERA - especially at large x and Q2. The extraction of g1n also presents an opportunity to refine the description of nuclear effects in spin-dependent structure functions. In the region of small x one must correct for shadowing and meson exchange current effects to explore the flavor structure of sea, which is, in turn, deeply related to the chiral structure of the nucleon. (orig.)
On the nucleon-nucleon potential obtained from non-linear coupling
International Nuclear Information System (INIS)
The static limit of a pseudoscalar symmetric meson theory of nuclear forces is examined. The Born-Oppenheimer potential is determined for the case of two very heavy nucleons exchanging pseudoscalar isovector pions with non-linear coupling. It is found that the non-linear terms induced by the γ5 coupling are cancelled by the additional pion-nucleon coupling of the non-linear sigma model. The nucleon-nucleon potential thus obtained is the same as the Yukava potential except for strength at different separations between the two nucleons
Three Dimensional Imaging of the Nucleon — TMD (Theory and Phenomenology)
Liang, Zuo-Tang
2016-02-01
This is intend to provide an overview of the theory and phenomenology parts of the TMD (Transverse Momentum Dependent parton distribution and fragmentation functions) studies. By comparing with the theoretical framework that we have for the inclusive deep inelastic lepton-nucleon scattering and the one-dimensional imaging of the nucleon, I try to outline what we need to do in order to construct a comprehensive theoretical framework for semi-inclusive reactions and the three dimensional imaging of the nucleon. After that, I try to give an overview of what we have already achieved and make an outlook for the future.
Polarization of Tau Leptons Produced in Quasielastic Neutrino--Nucleon Scattering
Kuzmin, Konstantin S; Naumov, Vadim A
2004-01-01
A numerical analysis of the polarization vector of tau leptons produced through quasielastic neutrino and antineutrino scattering off free nucleons is given for different models for the electromagnetic nucleon form factors. Possible impact of second class currents (SCC) is investigated. In the absence of a specific model for the vector and axial SCC, we adopt simple parametrizations for the nonstandard nucleon form factors with the parameters which satisfy the limits obtained in muon neutrino experiments and restrictions on SCC derived from the nuclear structure studies.
Unravelling the physical meaning of the Jaffe-Manohar decomposition of the nucleon spin
Wakamatsu, Masashi
2016-01-01
A general consensus now is that there are two physically inequivalent complete decompositions of the nucleon spin, i.e. the decomposition of the canonical type and that of mechanical type. The well-known Jaffe-Manohar decomposition is of the former type. Unfortunately, there is a wide-spread misbelief that this decomposition matches the partonic picture, which states that motion of quarks in the nucleon is approximately free. In the present monograph, we reveal that this understanding is not necessarily correct and that the Jaffe-Manohar decomposition is not such a decomposition, which natively reflects the intrinsic (or static) orbital angular momentum structure of the nucleon.
Nucleon shape and electromagnetic form factors in the chiral constituent quark model
Dahiya, Harleen
2010-01-01
The electromagnetic form factors are the most fundamental quantities to describe the internal structure of the nucleon and the shape of a spatially extended particle is determined by its intrinsic quadrupole moment which can be related to the charge radii. We have calculated the electromagnetic form factors, nucleon charge radii and the intrinsic quadrupole moment of the nucleon in the framework of chiral constituent quark model. The results obtained are comparable to the latest experimental studies and also show improvement over some theoretical interpretations.
Towards a microscopic understanding of nucleon polarizabilities
Eichmann, Gernot
2016-01-01
We outline a microscopic framework to calculate nucleon Compton scattering from the level of quarks and gluons within the covariant Faddeev approach. We explain the connection with hadronic expansions of the Compton scattering amplitude and discuss the obstacles in maintaining electromagnetic gauge invariance. Finally we give preliminary results for the nucleon polarizabilities.
Etaprime interactions with nucleons and nuclei
Bass, Steven D
2015-01-01
We summarise recent progress in theory and experiment towards understanding etaprime meson interactions with nucleons and nuclei. Highlights include the production mechanism of etaprime mesons in proton-proton collisions close to threshold, the etaprime effective mass shift in nuclei and the determination of the etaprime-nucleon scattering length in free space.
Nucleon-XcJ Dissociation Cross Sections
Institute of Scientific and Technical Information of China (English)
冯又层; 许晓明; 周代翠
2002-01-01
Nucleon-XcJ dissociation cross sections are calculated in a constituent interexchange model in which quark-quark potential is derived from the Buchmüller-Tye quark-anti-quark potential. These new cross sections for dominant reaction channels depend on the centre-of-mass energy of the nucleon and the charmonium.
Towards a Microscopic Understanding of Nucleon Polarizabilities
Eichmann, Gernot
2016-07-01
We outline a microscopic framework to calculate nucleon Compton scattering from the level of quarks and gluons within the covariant Faddeev approach. We explain the connection with hadronic expansions of the Compton scattering amplitude and discuss the obstacles in maintaining electromagnetic gauge invariance. Finally we give preliminary results for the nucleon polarizabilities.
Orbital Angular Momentum in the Nucleon
Garvey, Gerald T.
2010-01-01
Analysis of the measured value of the integrated \\bar{d}-\\bar{u} asymmetry (Ifas = 0.147+-0.027) in the nucleon show it to arise from nucleon fluctuations into baryon plus pion. Requiring angular momentum conservation in these fluctuations shows the associated orbital angular momentum is equal to the value of the flavor asymmetry.
Charge-symmetry-breaking nucleon form factors
Kubis, Bastian
2009-01-01
A quantitative understanding of charge-symmetry breaking is an increasingly important ingredient for the extraction of the nucleon's strange vector form factors. We review the theoretical understanding of the charge-symmetry-breaking form factors, both for single nucleons and for Helium-4.
Structural and functional diversity of desmosomes.
Harmon, Robert M; Green, Kathleen J
2013-12-01
Desmosomes anchor intermediate filaments at sites of cell contact established by the interaction of cadherins extending from opposing cells. The incorporation of cadherins, catenin adaptors, and cytoskeletal elements resembles the closely related adherens junction. However, the recruitment of intermediate filaments distinguishes desmosomes and imparts a unique function. By linking the load-bearing intermediate filaments of neighboring cells, desmosomes create mechanically contiguous cell sheets and, in so doing, confer structural integrity to the tissues they populate. This trait and a well-established role in human disease have long captured the attention of cell biologists, as evidenced by a publication record dating back to the mid-1860s. Likewise, emerging data implicating the desmosome in signaling events pertinent to organismal development, carcinogenesis, and genetic disorders will secure a prominent role for desmosomes in future biological and biomedical investigations.
Structural and Functional Views of Mechatronic Products
DEFF Research Database (Denmark)
Nielsen, Kjeld; Petersen, Thomas Ditlev; Jørgensen, Kaj Asbjørn
2011-01-01
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......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...... 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:...
Macrodomains: Structure, Function, Evolution, and Catalytic Activities.
Rack, Johannes Gregor Matthias; Perina, Dragutin; Ahel, Ivan
2016-06-01
Recent developments indicate that macrodomains, an ancient and diverse protein domain family, are key players in the recognition, interpretation, and turnover of ADP-ribose (ADPr) signaling. Crucial to this is the ability of macrodomains to recognize ADPr either directly, in the form of a metabolic derivative, or as a modification covalently bound to proteins. Thus, macrodomains regulate a wide variety of cellular and organismal processes, including DNA damage repair, signal transduction, and immune response. Their importance is further indicated by the fact that dysregulation or mutation of a macrodomain is associated with several diseases, including cancer, developmental defects, and neurodegeneration. In this review, we summarize the current insights into macrodomain evolution and how this evolution influenced their structural and functional diversification. We highlight some aspects of macrodomain roles in pathobiology as well as their emerging potential as therapeutic targets. PMID:26844395
Low-energy pion double charge exchange and nucleon-nucleon correlations in nuclei
International Nuclear Information System (INIS)
Recent measurements of pion double-charge exchange (DCX) at energies 20 to 70 MeV are providing a new means for studying nucleon-nucleon correlations in nuclei. At these energies the nucleus is relatively transparent, allowing simpler theoretical models to be used in interpreting the data and leading to a clearer picture. Also the contribution to DCX of sequential charge-exchange scattering through the intermediate analog state is suppressed near 50 MeV and transitions through non-analog intermediate states become very important. Recent theoretical studies by several groups have shown that while transitions through the analog route involve relatively long nucleon-nucleon distances, those through non-analog intermediate states obtain nearly half their strength from nucleon pairs with less than 1 fermi separation. Thus DCX near 50 MeV is an excellent way to study short-range nucleon-nucleon correlations. 31 refs., 29 figs., 4 tabs
Unitary three-body calculation of nucleon-nucleon scattering
International Nuclear Information System (INIS)
We calculate nucleon-nucleon elastic scattering phase parameters based on a unitary, relativistic, pion-exchange model. The results are highly dependent on the off-shell amplitudes of πN scattering. The isobar-dominated model for the P33 interaction leads to too small pion production rates owing to its strong suppression of off-shell pions. We propose to expand the idea of the Δ-isobar model in such a manner as to incorporate a background (non-pole) interaction. The two-potential model, which was first applied to the P11 partial wave by Mizutani and Koltun, is applied also to the P33 wave. Our phenomenological model for πN interaction in the P33 partial wave differs from the conventional model only in its off-shell extrapolation, and has two different variants for the πN → Δ vertex. The three-body approach of Kloet and Silbar is extended such that the background interactions can be included straightfowardly. We make detailed comparisons of the new model with the conventional one and find that our model adequately reproduces the 1D2 phase parameters as well as those of peripheral partial waves. We also find that the longitudinal total cross section difference ΔσL(pp → NNπ) comes closer to the data compared to Kloet and Silbar. We discuss about the backward pion propagation in the three-body calculation, and the Pauli-principle violating states for the background P11 interaction. (author)