Nucleon structure functions from a chiral soliton
International Nuclear Information System (INIS)
We study nucleon structure functions within the bosonized version of the Nambu-Jona-Lasinio (NJL) model in which the nucleon emerges as the soliton in the chiral field. Upon boosting to the infinite momentum frame and performing the q2-evolution in the context of the Gottfried sum rule for electron nucleon scattering we determine the intrinsic scale ?2 of the NJL chiral soliton. We also compute the leading twist contributions of the polarized structure functions g1 and g2. We compare these model predictions with experiment by evolving them from ?2 to the scale where the data are taken. Analogously we analyze the chiral-odd structure functions hT and hL. Finally we generalize the treatment to flavor SU(3)
Experimental results on polarized nucleon structure functions
Energy Technology Data Exchange (ETDEWEB)
Ketel, T.J. [Department of Physics and Astronomy, Free University Amsterdam (Netherlands); Spin Muon Collaboration at CERN
1998-05-01
Experimental results of deep inelastic scattering of polarized leptons from polarized target nucleons are reviewed. Accurate values of the spin dependent structure function g{sub 1} (x) were obtained in experiments covering a large kinematic range. The combination of all experimental results confirms the validity of the Bjorken sum rule. (author) 14 refs, 7 figs, 2 tabs
Nucleon neutral-current structure functions
International Nuclear Information System (INIS)
The structure of the nucleon is studied by means of deep-inelastic neutrino-nucleon scattering at high energies through the weak neutral current. The neutrino-nucleon scattering events were observed in a 340-metric-ton fine-grained calorimeter exposed to a narrow-band (dichromatic) neutrino beam at Fermilab. The data sample after analysis cuts consists of 9200 charged-current and 3000 neutral-current neutrino and antineutrino events. The neutral-current valence and sea nucleon structure functions are extracted from the x distribution reconstructed from the measured angle and energy of the recoil-hadron shower and the incident narrow-band neutrino-beam energy. They are compared to those extracted from charged-current events analyzed as neutral-current events. It is shown that the nucleon structure is independent of the type of neutrino interaction, which confirms an important aspect of the standard model. The data are also used to determine the value of sin2?W=0.238±0.013±0.015±0.010 for a single-parameter fit, where the first error is from statistical sources, the second from experimental systematic errors, and the third from estimated theoretical errors
Nucleon structure functions and light front dynamics
Traini, Marco; Faccioli, Pietro; Vento Torres, Vicente
1999-01-01
We present a quark-parton model to describe polarized and unpolarized nucleon structure functions. The twist-two matrix elements for the QCD evolution analysis of lepton-hadron scattering are calculated within a light-front covariant quark model. The relativistic effects in the three-body wave function are discussed for both the polarized and unpolarized cases. Predictions are given for the polarized gluon distributions as will be seen in future experiments.
Nucleon Structure Functions from a Chiral Soliton
Weigel, Herbert
1998-10-01
In an attempt to merge the parton model description of deep inelastic scattering with the phenomenologically successful picture of baryons as chiral solitons we study nucleon structure functions in the Nambu--Jona--Lasinio (NJL) chiral soliton model(R. Alkofer, H. Reinhardt and H. Weigel, Phys. Rep. 265) (1996) 139.. We compute the unpolarized structure function for electron--nucleon scattering which enters the Gottfried sum rule, S_G. The model calculation not only explains the observed deviation from the historical value S_G=1/3 but also reproduces the gross features of the exerimental data when accounting for projection and Q^2--evolution(H. Weigel, L. Gamberg and H. Reinhardt, Mod. Phys. Lett. A11) (1996) 3021; Phys. Lett. B399 (1997) 287.. The latter operation further serves to determine the low--momentum scale, Q_0^2, of the model. Subsequently we turn to the polarized structure functions g_1(x,Q^2) and g_2(x,Q^2)(H. Weigel, L. Gamberg and H. Reinhardt, Phys. Rev. D55) (1997) 6910.. These are particularly interesting in the present model because chiral soliton models nicely account for the smallness of the first moment of g_1(x,Q^2). In addition we report on the calculation(L. Gamberg, H. Reinhardt and H. Weigel, Phys. Rev. D58) (1998) 054014. of the chiral odd quark distributions and the corresponding structure functions h_T(x,Q^2) and h_L(x,Q^2). At the low model scale, Q_0^2, we find that the leading twist effective quark distributions, f_1^(q)(x,Q_0^2), g_1^(q)(x,Q_0^2) and h_T^(q)(x,Q_0^2) satisfy Soffer's inequality for both quark flavors q=u,d. The Q^2 evolution of the twist--2 contributions is performed according to the standard GLAP formalism while the twist--three pieces, \\overlineg_2(x) and \\overlineh_L(x), are evolved according to the large NC scheme. Finally we explain the generalization of chiral soliton models to three flavors and discuss the strange quark contribution to g1 as an example(box[t]15cm)O. Schröder, H. Reinhardt and H. Weigel, ``Strangeness Contribution to the Polarized Nucleon Structure Function g_1'', hep--ph/9805251, Phys. Lett. B to appear..
Towards a lattice calculation of the nucleon structure functions
International Nuclear Information System (INIS)
We have initiated a programme to compute the lower moments of the unpolarised and polarised deep inelastic structure functions of the nucleon in the quenched approxiation. We review our progress to date. (orig.)
Nucleon structure functions at small $x$ via holographic Pomeron exchange
Watanabe, Akira
2015-01-01
The analysis on nucleon structure functions at small Bjorken $x$ in the framework of holographic QCD is presented. In the model setup, the complicated nonperturbative interaction between the virtual photon and the target nucleon is described via the Pomeron exchange, which corresponds to the reggeized graviton exchange in the AdS space. We show that our calculations for both $F_2$ and $F_L$ structure functions are in agreement with the experimental data measured at HERA.
A no extensive statistical model for the nucleon structure function
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Instituto de Ciencia, Engenharia e Tecnologia - ICET, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Campus do Mucuri, Rua do Cruzeiro 01, Jardim Sao Paulo, 39803-371, Teofilo Otoni, Minas Gerais (Brazil)
2013-03-25
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.
Polarized nucleon structure functions within a chiral soliton model
International Nuclear Information System (INIS)
We study polarized-spin structure functions of the nucleon within the bosonized Nambu endash Jona-Lasinio model where the nucleon emerges as a chiral soliton. We present the electromagnetic polarized structure functions g1(x) and g2(x) for ep scattering and discuss various sum rules in the valence quark approximation. This approximation is justified because in this model axial properties of the nucleon are dominated by their valence quark contributions. We find that these structure functions are well localized in the interval 0?x?1. We compare the model predictions on the polarized structure functions with data from the E143 experiment by evolving them from the scale characteristic of the NJL model to the scale of the data. Additionally, a comparison is made with parametrized data at a momentum scale commensurate with the model calculation. copyright 1997 The American Physical Society
Nucleon structure functions in a chiral soliton model
International Nuclear Information System (INIS)
The computation of nucleon structure functions within the Nambu-Jona-Lasinio chiral soliton model is outlined. After some technical remarks on the issue of regularization numerical results for the both unpolarized and polarized structure functions are presented. The generalization to flavor SU(3) is sketched
Nucleon structure functions in a chiral soliton model
Energy Technology Data Exchange (ETDEWEB)
Weigel, Herbert
2000-05-08
The computation of nucleon structure functions within the Nambu-Jona-Lasinio chiral soliton model is outlined. After some technical remarks on the issue of regularization numerical results for the both unpolarized and polarized structure functions are presented. The generalization to flavor SU(3) is sketched.
Experiments on nucleon spin-dependent structure functions
Energy Technology Data Exchange (ETDEWEB)
Igo, G. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Hughes, V.W. [Yale Univ., New Haven, CT (United States). Dept. of Physics
1991-12-31
In this presentation, the earlier measurements of the spin-dependent structure function of the proton in experiments at SLAC and at CERN are reviewed. In addition several new deep inelastic scattering experiments to measure the spin-dependent structure functions of the nucleon, both proton and neutron, will be discussed.
Experiments on nucleon spin-dependent structure functions
Energy Technology Data Exchange (ETDEWEB)
Igo, G. (California Univ., Los Angeles, CA (United States). Dept. of Physics); Hughes, V.W. (Yale Univ., New Haven, CT (United States). Dept. of Physics)
1991-01-01
In this presentation, the earlier measurements of the spin-dependent structure function of the proton in experiments at SLAC and at CERN are reviewed. In addition several new deep inelastic scattering experiments to measure the spin-dependent structure functions of the nucleon, both proton and neutron, will be discussed.
Energy Technology Data Exchange (ETDEWEB)
Bertini, M.
1995-05-12
This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F{sub 2}) and polarized (g{sub 1}) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F{sub 2} and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions g{sup p,n,d} and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends.
The nucleon structure function and the quark effective potential
International Nuclear Information System (INIS)
A statistical quark model is considered in order to reproduce the nucleon structure function , by using a temperature parameter to adjust the Gottfried sum rule. In the present statistical model, the quark levels in the nucleon are generated by a Dirac equation with harmonic scalar plus vector potential. We note that a good fit for the ratio between the structure functions of the neutron and proton, F2n/F2p, can be obtained if different strengths are used for the effective confining potentials of the up and down quarks. (author)
Truncated Moment Analysis of Nucleon Structure Functions
Energy Technology Data Exchange (ETDEWEB)
A. Psaker; W. Melnitchouk; M. E. Christy; C. E. Keppel
2007-11-16
We employ a novel new approach using "truncated" moments, or integrals of structure functions over restricted regions of x, to study local quark-hadron duality, and the degree to which individual resonance regions are dominated by leading twists. Because truncated moments obey the same Q^2 evolution equations as the leading twist parton distributions, this approach makes possible for the first time a description of resonance region data and the phenomenon of quark-hadron duality directly from QCD.
Determination of nucleon structure functions from neutrino-iron scattering
International Nuclear Information System (INIS)
In the present thesis from inelastic neutrino-iron scattering the nucleon structure functions 2xF1, F2, xF3, anti q are determined. The data acquisition was performed 1983 at CERN in the 400 GeV neutrino broad-band beam with the improved CDHS detector. The statistics could be essentially raised against the last CDHS structure-function measurement. (orig./HSI)
Diquark contributions to the nucleon deep inelastic structure functions
International Nuclear Information System (INIS)
The contributions of diquarks to the nucleon structure functions are discussed in the framework of the parton model and in the most general case of both vector and scalar diquarks inside unpolarized and polarized nucleons. The vector diquark anomalous magnetic moment and the scalar-vector and vector-scalar diquark transitions are also taken into account. The properties of the diquarks and of their form factors, required in order for the resulting scaling violations to be compatible with the observed ones, are discussed. (author)
Measurements of spin structure functions of the nucleon
International Nuclear Information System (INIS)
After a recall of the history of researches on nucleon structure, this research thesis addresses the measurements of spin structure functions of a proton and of a neutron as they have been performed during the NA47 experiment at the CERN. The author first develops the formalism of the deeply inelastic scattering of polarised leptons on polarised nucleons, with a peculiar attention to the definition of structure functions. The various obtained results are re-determined in a more general framework based on the Operator Product Expansion formalism which allows, within the framework of Quantum Chromodynamics, to relate some moments of structure functions to elements of hadron matrices. The author then describes the experimental situation for the measurement of the proton spin structure function at the end of the 1980's, and presents the experimental installation of the NA47 experiment. Reconstruction programs are then addressed, and the author explains how he determines, event by event, the kinematics of the highly inelastic scattering of a muon on a nucleon, and the vertex position within the target. Sources of errors are identified, and the author presents methods aimed at reducing and at assessing the detection efficiency of all detectors, and of their evolutions in time. The author explains how results on asymmetries and structure functions are extracted from counting rates associated with two cells, as well as the method of calculation of various systematic errors associated with these asymmetries and structure functions. He finally presents results obtained for the measurement of the spin structure function for the proton and for the deuton. The Ellis-Jaffe sum rule is then tested, and spin share of the nucleon born by quarks is determined. Results are compared with those of other experiments, and the Bjorken sum rule is also tested
Nucleon structure functions and light-front dynamics
International Nuclear Information System (INIS)
We present a quark-parton model to describe polarized and unpolarized nucleon structure functions. The twist-two matrix elements for the QCD evolution analysis of lepton-hadron scattering are calculated within a light-front covariant quark model. The relativistic effects in the three-body wave function are discussed for both the polarized and unpolarized cases. Predictions are given for the polarized gluon distributions as will be seen in future experiments. Refs. 16 (author)
Spin And Nuclear Effects In Nucleon Structure Function
International Nuclear Information System (INIS)
Full text: The two experimental results on the structure functions of the nucleon obtained by the European muon collaboration (EMC) from the experiments on deep inelastic scattering of muons on nuclear and scattering of polarized muons on polarized nucleons have become a source of great confusion. From these data the surprising and counter- intuitive results have been obtained indicating that quark distribution in nuclear nucleon is much different than in that free nucleon (so-called nuclear EMC effect) and the total projection of the spin of all quarks and antiquarks in the direction of the spin of the polarized nucleon is close to zero (so-called spin crisis). It is shown that the suppression of soft-gluon emission in the evolution of the nonsinglet structure function of a nucleon within a nucleus describes to a certain extent the EMC effect. High order corrections to the photon polarization degree due to radiative emissions at longitudinal polarized deep inelastic lepton-nucleon scattering are calculated in the framework of the structure-function formalism. We consider the changing of polarization degree of the virtual photon due to the initial state radiation of real photons at longitudinal polarized lepton-nucleon scattering. Usually the photon depolarization factor is taken into account only in low order of perturbative theory. To take into account the radiative correction we used the structure function method for the polarization case. The Born cross section at deep-inelastic lepton-nucleon scattering is modified due to additional real and virtual bosons from either the lepton or quark line. The quarkonic corrections are absorbed into quark structure function, like the gluon radiation, whereas corrections from interference between the lepton and quark line proved to be small. The dominant contribution to the virtual corrections is the vertex corrections and the vacuum polarization. In leading logarithmical approximation, the emitted real photon is collinear with initial (final) lepton. The radiative corrections (RC) change the kinematics of the events. We find that the RC changes the structure of depolarization factor and there is big difference between low and high order at small value of energy fraction of the virtual photon. Therefore, it is necessary to use the expression of photon depolarization factor in high order. It has been shown that the associate production of a J/? meson and a photon at polarized proton-proton collisions can serve as a very clean probe of the gluon polarization. It presents the calculations of the differential cross section for the production with a high transverse momentum of J/? (Jpc = 1--) meson accompanied by the hard photon at the CERN in Large Hadron Collider (LHC) proton-proton (pp) collisions at the energy ?s =14 TeV : p+p = J/?+?+X. In low order J/? meson and photon in the final state with high transverse momenta can only be produced via QCD gluon fusion: g+g = J/?+?. The associated production of a J/? meson and a photon at the LHC energy should not be dominated by fragmentation contributions up to transverse momentum pt values of 50 GeV. This should be due to the fact that quark-antiquark (qq- ) initial states are suppressed at the CERN LHC energy. We use the following cuts: pt?40 GeV. The method to extract the gluon structure function can be based on fitting the J/?-? cross section to the predictions. (authors)
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.
A measurement of the ratio of the nucleon structure function in copper and deuterium
International Nuclear Information System (INIS)
Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function, F2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects. (orig.)
Collinear Structure Functions of the Nucleon: Status and Future
International Nuclear Information System (INIS)
While our ultimate goal is a complete three-dimensional picture of the nucleon in terms of its fundamental constituents, there are still important lessons to be learned about its ''one-dimensional'' collinear parton distribution functions (PDFs) like f1(x) and g1(x). There are rigorous proofs for factorization and universality (process independence) which make these PDFs fundamental. They also appear as limits of Generalized Parton Distributions (GPD) and as integrals of transverse momentum-dependent (TMD) parton distribution functions. Experimentally, the unpolarized structure functions F1(x,Q2), F2(x,Q2) have been studied over a huge kinematic range in both variables. Information on the polarized structure functions g1(x,Q2), g2(x,Q2) is somewhat more limited, both in kinematics and in statistical precision. In both cases, much less is known about the neutron than the proton, due to the absence of a free neutron target. Accessing these structure functions at large x (where valence quarks dominate) has been challenging due to the high luminosity and the high resolution required. Finally, much information can be extracted from studying higher twist contributions to these structure functions and the connection between the DIS limit and the region where nucleon resonance excitation dominates. In my talk, I will present an overview of recent experimental results (with special emphasis on the valence region and the transition from quark to hadronic degrees of freedom). I will also give an outlook on the next round of experiments coming online with the energy-upgraded Jefferson Lab electron beam, and future projects like the Electron Ion Collider
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/ = 1.4âˆšnu(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 Î›/sub LO/ = 230 +- 40/sup stat/ +- 80/sup syst/ MeV/c, assuming R = 0 and without applying Fermi motion corrections. Comparing the cross sections at the two beam energies, we measure R = -0.06 +- 0.06/sup stat/ +- 0.11/sup syst/. Our measurements show qualitative agreement with QCD, but quantitative comparison is hampered by phenomenological uncertainties. The experimental situation is quite good, with substantial agreement between our measurements and those of others. 86 references
Bound nucleon structure function in the picture of relativistic constituent quarks
International Nuclear Information System (INIS)
The structure function F2N of nucleons in the deuterium, carbon and iron nuclei is calculated as a function of Q2 in two approaches: taking into account the nucleon swelling in nuclei due to the partial deconfinement of quarks in nuclear medium; in the conventional approach of nuclear physics, taking into account the getting off the mass shell of the bound nucleon and Fermi motion in nucleons. It is shown that the conventional approach of nuclear physics does not explain the EMC effect in the region of small x
On the off-mass-shell deformation of the nucleon structure function
Umnikov, A Yu; Kaptari, L P; Umnikov, A Yu; Khanna, F C; Kaptari, L P
1994-01-01
The off-mass-shell behavior of the nucleon structure function, F_2^N, is studied within an approach motivated by the Sullivan model. Deep inelastic scattering on the nucleon is considered in the second order in the pion-nucleon coupling constant, corresponding to the dressing of the bare nucleons by the mesonic cloud. The inclusive and semi-inclusive deep inelastic processes on the deuteron involving off-shell nucleons are considered. A deformation of the mesonic cloud for the off-mass-shell nucleon, compared to the free one, generates observable effects in deep inelastic scattering. In particular, it leads to the breakdown of the convolution model, i.e. the deuteron structure functions are not expressed through the free nucleon structure function. Analysis of the semi-inclusive deep inelastic scattering on the deuteron, in the spectator approximation, shows that this reaction opens new possibilities to study the role of the off-shell effects in determining in detail the nucleon structure function.
Structure functions of bound nucleons: from the EMC effect to nuclear shadowing
International Nuclear Information System (INIS)
We describe the nuclear structure functions in the whole range of the Bjorken variable x, by combining various effects in a many-step procedure. First, we present a QCD motivated model of nucleons, treated, in the limit of vanishing Q2, as bound states of three relativistic constituent quarks. Gluons and sea quarks are generated radiatively from the input valence quarks. All parton distributions are described in terms of the confinement (or nucleon's) radius. The results for free nucleons are in agreement with the experimental determinations. The structure functions of bound nucleons are calculated by assuming that the main effect of nucleon binding is stretching of nucleons. The larger size of bound nucleons lowers the valence momentum and enhances the radiatively generated glue and sea densities. In the small-x region the competitive mechanism of nuclear shadowing takes place. It also depends on the size of the nucleons. By combining stretching, shadowing and Fermi motion effects (the latter confined to very large x), the structure function ratio is well reproduced. Results are also presented for the A-dependence of the momentum integral of charged partons, the nuclear gluon distribution and the hadron-nuclei cross sections. (orig.)
Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons
Energy Technology Data Exchange (ETDEWEB)
Bodek, Arie [University of Rochester, Rochester, NY
2015-09-01
We present preliminary results on an experimental study of the nuclear modification of the longitudinal (sL) and transverse (sT ) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= sL=sT for nuclei (RA) and for deuterium (RD) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, RA < RD.
Linear estimates of structure functions from deep inelastic lepton-nucleon scattering data. Part 2
International Nuclear Information System (INIS)
The paper concerns the linear estimation of structure functions from (anti)neutrino-nucleon scattering. The expressions obtained for the structure functions estimate provide correct analysis of their random error and the bias. The bias arises because of the finite number of experimental data and the finite resolution of experiment. 10 refs
Zhu, Wei; Ruan, Jianhong
2015-10-01
This paper contains three parts relating to the nucleon spin structure in a simple picture of the nucleon: (i) The polarized gluon distribution in the proton is dynamically predicted starting from a low scale by using a nonlinear quantum chromodynamics (QCD) evolution equation — the Dokshitzer-Gribov-Lipatov-Altarelli-Paris (DGLAP) equation with the parton recombination corrections, where the nucleon is almost consisted only of valence quarks. We find that the contribution of the gluon polarization to the nucleon spin structure is much larger than the predictions of most other theories. This result suggests that a significant orbital angular momentum of the gluons is required to balance the gluon spin momentum. (ii) The spin structure function g1p of the proton is studied, where the perturbative evolution of parton distributions and nonperturbative vector meson dominance (VMD) model are used. We predict g1p asymptotic behavior at small x from lower Q2 to higher Q2. The results are compatible with the data including the early HERA estimations and COMPASS new results. (iii) The generalized Gerasimov-Drell-Hearn (GDH) sum rule is understood based on the polarized parton distributions of the proton with the higher twist contributions. A simple parameterized formula is proposed to clearly present the contributions of different components in the proton to ? 1p(Q2). The results suggest a possible extended objects with size 0.2-0.3 fm inside the proton.
Nucleon spin structure function from the instanton vacuum
International Nuclear Information System (INIS)
We discuss the evaluation of the nucleon isoscalar axial coupling, gA(0), in the instanton vacuum using the 1/NC expansion. This approach allows a fully consistent treatment of the U(1)A anomaly. We compute the nucleon matrix element of the topological charge, , and show that it reduces to the matrix element of the isoscalar axial quark current. Our arguments show that the usual evaluation of gA(0) in the chiral quark soliton model is consistent with the U(1)A anomaly in leading order of 1/NC. Such calculations give gA(0) = 0.36, which is in agreement with the recent estimate by Ellis and Karliner. (author)
Nucleon spin structure function from the instanton vacuum
Energy Technology Data Exchange (ETDEWEB)
Weiss, C. [Inst. fuer Theoretishe Physik 2, Ruhr Univ. Bochum, Bochum (Germany)
1996-06-01
We discuss the evaluation of the nucleon isoscalar axial coupling, g{sub A}{sup (0)}, in the instanton vacuum using the 1/N{sub C} expansion. This approach allows a fully consistent treatment of the U(1){sub A} anomaly. We compute the nucleon matrix element of the topological charge,
The polarized structure function of the nucleons with a non-extensive statistical quark model
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Instituto de Ciencia, Engenharia e Tecnologia - ICET, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Campus do Mucuri, Rua do Cruzeiro 01, Jardim Sao Paulo, 39803-371, Teofilo Otoni, Minas Gerais (Brazil)
2013-05-06
We studied an application of nonextensive thermodynamics to describe the polarized structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution, often used in the statistical models, were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and the chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon and by {Delta}u and {Delta}d of the polarized functions.
Recent lattice QCD results on nucleon structure
Energy Technology Data Exchange (ETDEWEB)
Konstantinos Orginos
2006-06-25
I review recent developments in lattice calculations of nucleon structure. In particular, I cover the calculations of nucleon matrix elements related to generalized parton distribution functions, structure functions and form factors.
Recent lattice QCD results on nucleon structure
Energy Technology Data Exchange (ETDEWEB)
Konstantinos Orginos
2006-07-01
I review recent developments in lattice calculations of nucleon structure. In particular, I cover the calculations of nucleon matrix elements related to generalized parton distribution functions, structure functions and form factors.
The ratio of the nucleon structure functions Fsup(N)2 for iron and deuterium
International Nuclear Information System (INIS)
Using the data on deep inelastic muon scattering on iron and deuterium the ratio of the nucleon structure functions F2sup(N)(Fe)/F2sup(N)(D) is presented. The observed x-dependence of this ratio is in disagreement with existing theoretical predictions. (orig.)
Linear estimates of structure functions from deep inelastic lepton-nucleon scattering data. Part 1
International Nuclear Information System (INIS)
This paper concerns the linear estimation of structure functions from muon(electron)-nucleon scattering. The expressions obtained for the structure functions estimate provide correct analysis of the random error and the bias The bias arises because of the finite number of experimental data and the finite resolution of experiment. The approach suggested may become useful for data handling from experiments at HERA. 9 refs
Study of the spin structure functions of the nucleon: the E143 experiment at SLAC
International Nuclear Information System (INIS)
In this thesis, we present the results of the E143 experiment of deep inelastic scattering of 29 GeV polarized electrons from polarized NH3 and ND3 targets, at SLAC. The goal of the experiment is the measurement of the spin structure functions g1 and g2 of the nucleon which provide information on its internal spin structure. Experimentally, the structure functions are extracted from the measurement of cross section asymmetries. Our measured values of the first moment of g1 are two and three standard deviations below the Ellis-Jaffe sum rule predictions, for the proton and for the deuteron, respectively. The Bjoerken sum rule, a QCD fundamental prediction, has been confirmed. We find the quark contribution to the nucleon spin to be around 30 pc. Our results on g2 are well described by the Wandzura-Wilczek expression. (author)
Target Mass Corrections to QCD Bjorken Sum Rule for Nucleon Spin Structure Functions
Kawamura, Hiroyuki; UEMATSU, Tsuneo
1995-01-01
We discuss the possible target mass corrections in the QCD analysis of nucleon's spin-dependent structure functions measured in the polarized deep-inelastic leptoproduction. The target mass correction for the QCD Bjorken sum rule is obtained from the Nachtmann moment and its magnitude is estimated employing positivity bound as well as the experimental data for the asymmetry parameters. We also study the uncertainty due to target mass effects in determining the QCD effective ...
Moments of nuclear and nucleon structure functions at low Q2 and the momentum sum rule
International Nuclear Information System (INIS)
New nuclear structure function data from Jefferson Lab covering the higher x and lower Q2 regime make it possible to extract the higher order F2 moments for iron and deuterium at low four-momentum transfer squared Q2. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the non-singlet nucleon moment with Lattice QCD results
Structure function measurements in the deep inelastic muon-nucleon scattering
International Nuclear Information System (INIS)
Measurements of deep inelastic scattering events on a combined copper and deuterium target were performed by the European Muon Collaboration (EMC) using a muon beam at CERN's SPS with energies at 100 GeV and 280 GeV. The data are analysed and compared with a detailed Monte-Carlo simulation and allow the determination of structure functions from both targets. In the light of the present discrepancy between EMC's and BCDMS's structure functions, stringend cuts were applied to the data. The results confirm the EMC structure function measurements on unbound nucleons. The comparison between the copper structure function from this experiment and the NA2 iron structure function shows a trend to lower values at low xBj. (orig.)
Spin structure functions of the nucleon at low Q2 and ?
International Nuclear Information System (INIS)
Phenomenological approaches to describe the spin structure functions an spin sum rules for proton and neutrons at low momentum transfer Q2 and energy transfer ?, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A1p, A2p and N1n structure functions at CEBAF in a Q2 range from 0.15 to 2.0 GeV2, and a W range from threshold to 2.2 GeV are presented
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.
International Nuclear Information System (INIS)
We present a model description of the nucleon valence structure function applicable over the entire region of the Bjorken variable x, and above moderate values of Q2 (?1 GeV2). We stress the importance of describing the complete spectrum of intermediate states which are spectator to the deep-inelastic collision. At a scale of 1 GeV2 the relevant degrees of freedom are constituent quarks and pions. The large-x region is then described in terms of scattering from constituent quarks in the nucleon, while the dressing of constituent quarks by pions plays an important role at intermediate x values. The correct small-x behavior, which is necessary for the proper normalization of the valence distributions, is guaranteed by modeling the asymptotic spectator mass spectrum according to Regge phenomenology. (orig.)
A detailed study of the nucleon structure functions in deep inelastic muon scattering in iron
International Nuclear Information System (INIS)
The chi and Q2 dependences of the nucleon structure functions F2sup(N)(chi,Q2) and Rsup(N)(chi,Q2) have been measured in deep inelastic muon scattering from an iron target in the region 0.0422. By comparing data taken at different incident muon energies Rsup(N) was found to be small with an average value of 0.026+-0.037 (stat.)+-0.174 (syst.). The observed deviations from scaling gave the value of the QCD mass scale parameter theta. The fraction of the momentum of the nucleon carried by quarks was found to be (49+-1 stat.+-4 syst.)% at Q2proportional15 GeV2. (orig./HSI)
International Nuclear Information System (INIS)
In this thesis results of measurements of the differential cross sections of the elastic and inelastic electron deuteron scattering are presented. The data were taken at several scattering angles and in the electron energy range of 150 MeV up to 320 MeV. The extracted form factors and structure functions are compared with theoretical results which are sensitive to details of nucleon structure and of the nucleon-nucleon forces. (FKS)
Asymptotic solutions of the evolution equation for the polarized nucleon structure function g2(?,Q2)
International Nuclear Information System (INIS)
We show that quark operators of twist 3 contributing to the polarized nucleon structure function g2tw.3(x, Q2) decouple from the evolution equation for the quark-gluon operators of the same twist in two important limits, Nc?? and n?? (Nc is the number of colours and n refers to the n-th moment of g2). The anomalous dimensions for the quark operators turn out to be always the lowest ones in the spectrum. Asymptotic behaviour of g2(x, Q2) in the region 1-xc?? cases are presented. (orig.)
Strangeness content and structure function of the nucleon in a statistical quark model
Trevisan, L A; Tomio, L
1999-01-01
The strangeness content of the nucleon is determined from a statistical model using confined quark levels, and is shown to have a good agreement with the corresponding values extracted from experimental data. The quark levels are generated in a Dirac equation that uses a linear confining potential (scalar plus vector). With the requirement that the result for the Gottfried sum rule violation, given by the new muon collaboration (NMC), is well reproduced, we also obtain the difference between the structure functions of the proton and neutron, and the corresponding sea quark contributions. (27 refs).
Modelling the nucleon structure
Burkardt, M
2015-01-01
We review the status of our understanding of nucleon structure based on the modelling of different kinds of parton distributions. We use the concept of generalized transverse momentum dependent parton distributions and Wigner distributions, which combine the features of transverse-momentum dependent parton distributions and generalized parton distributions. We revisit various quark models which account for different aspects of these parton distributions. We then identify applications of these distributions to gain a simple interpretation of key properties of the quark and gluon dynamics in the nucleon.
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 using lattice QCD
International Nuclear Information System (INIS)
A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distribution are discussed, assessing the methods applied for their study, including approaches to evaluate the disconnected contributions. Results on the spin carried by the quarks in the nucleon are also presented.
Nucleon structure using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, C.; Kallidonis, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Constantinou, M.; Hatziyiannakou, K. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Drach, V. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Jansen, K. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Koutsou, G.; Vaquero, A. [The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Leontiou, T. [Frederick Univ, Nicosia (Cyprus). General Dept.
2013-03-15
A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distribution are discussed, assessing the methods applied for their study, including approaches to evaluate the disconnected contributions. Results on the spin carried by the quarks in the nucleon are also presented.
Axial structure of the nucleon
Bernard, VÃ©ronique(Institut de Physique NuclÃ©aire, CNRS/Univ. Paris-Sud 11 (UMR 8608), Orsay Cedex, F-91406, France); Elouadrhiri, Latifa; MeiÃŸner, Ulf-G.
2001-01-01
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
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.
Nematollahi, H.; Yazdanpanah, M. M.
2015-07-01
We investigate the structure of the light nuclei based on the modified chiral quark model (? QM ) , for the first time. To this end, we first calculate the parton distribution functions (PDFs) of the bounded nucleons using the ? QM and then compute those of the light nuclei. For this purpose, it is first needed to obtain the bare quark densities inside the bounded nucleons of the nucleus. These bare distributions are calculated by applying the quark exchange model (QEM) in this article. Finally, we obtain the quark, antiquark, and gluon distributions and also the structure functions (SFs) of the bound state nucleons and the light nuclei at low Q2 scale (Q2=0.35 GeV2) . These distributions can be evolved to the higher scales using DGLAP evolution equations. It is shown that the results of our theoretical framework are in good agreement with the experimental data and they also have appropriate behavior in comparison with the different parametrization models.
Study of the nucleon spin structure functions: the E154 experiment at SLAC
International Nuclear Information System (INIS)
In experiment E154 at SLAC, the spin dependent structure function g1n was measured by scattering longitudinally polarized 50 GeV electrons off a longitudinally polarized helium 3 target. We report the integral over the measured x range to be ?0.0140.7g1n(x,5 GeV2)dx = -0.0348 ± 0.0033 ± 0.0043 ± 0.0014. We observe relatively large values of g1n at low x, calling into question the reliability of the data extrapolation down to x equal 0. Such a divergent behavior seems to disagree with the prediction of the Regge theory but can be quantitatively explained by perturbative QCD. Moreover, we have performed a NLO perturbative QCD analysis of the world data on g1, paying careful attention to both the theoretical hypothesis and the calculation of errors. Using a parametrization of the polarized parton distribution at a low scale, we can access the fraction of spin carried by quarks: ?? = 29 ± 6 pc in the MS-bar scheme, and ?? = 37 ± 7 pc in the AB scheme. The gluon contribution to the nucleon spin is not well enough constrained by the current data, but seems to lie between 0 and 2. This study allows us to extract the first moment of the g1 structure function and we find agreement with the Bjorken sum rule expectations. (author)
Indian Academy of Sciences (India)
N Barik; R N Mishra
2001-04-01
Considering the nucleon as consisting entirely of its valence quarks con?ned independently in a scalar-vector harmonic potential; unpolarized structure functions $F_{1}(x,\\mu^{2})$ and $F_{2}(x,\\mu^{2})$ are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions $u_{v}(x,\\mu^{2})$ and $d_{v}(x,\\mu^{2})$ are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of $\\mu^{2}=0.07$ GeV2 to a higher $Q^{2}$ scale of $Q^{2}_{0} = 15$ GeV2 yields $xu_{v}(x, Q^{2}_{0})$ and $xd_{v}(x, Q^{2}_{0})$ in good agreement with experimental data. The gluon and sea-quark distributions such as $G(x,Q^{2}_{0})$ and $q_{s}(x, Q^{2}_{0})$ are dynamically generated with a reasonable qualitative agreement with the available data; using the leading order renormalization group equations with appropriate valence-quark distributions as the input.
Nucleon Structure from Lattice QCD
Richards, David
2007-01-01
Recent advances in lattice field theory, in computer technology and in chiral perturbation theory have enabled lattice QCD to emerge as a powerful quantitative tool in understanding hadron structure. I describe recent progress in the computation of the nucleon form factors and moments of parton distribution functions, before proceeding to describe lattice studies of the Generalized Parton Distributions (GPDs). In particular, I show how lattice studies of GPDs contribute to building a three-dimensional picture of the proton. I conclude by describing the prospects for studying the structure of resonances from lattice QCD.
Probing Nucleon Spin Structure
Ramsey, G P
1997-01-01
One of the important questions in high energy physics is the relation of quark and gluon spin to that of the nucleons which they comprise. Polarization experiments provide a mechanism to probe the spin properties of elementary particles and provide crucial tests of Quantum Chromodynamics (QCD). The theoretical and experimental status of this fundamental question will be reviewed in this paper.
International Nuclear Information System (INIS)
In consideration of the lowest order non-perturbative effect due to the quark condensate and gluon condensate on the quark propagator, we calculate QCD non-perturbative quark propagator under the chain approximation. Using the obtained non-perturbative quark propagator, we analyse the non-perturbative effect in the nucleon structure functions and show the non-trivial Q2-dependence in the nucleon structure functions
From nuclear structure to nucleon structure
International Nuclear Information System (INIS)
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
Nucleon structure from stochastic estimators
Energy Technology Data Exchange (ETDEWEB)
Najjar, Johannes Siegfried Samir
2014-10-01
The structure of the proton and neutron, parameterized by moments of generalized parton distribution functions (GPDs), can be accessed from first principle through the computation of baryon three-point functions with lattice QCD. The numerical effort involved in such computations is sizable and thus an efficient algorithm that extracts most information at given cost is highly desirable. In this work we demonstrate that stochastic estimation techniques can substantially increase the information/cost ratio. We examine the available results at N{sub f}=2 for the nucleon axial coupling gA and iso-vector quark momentum fraction
International Nuclear Information System (INIS)
We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 2 2. The data have been used to accurately perform over 170 Rosenbluth-type longitudinal/transverse separations. The precision R ?L/?T data are presented here, along with the first separate values of the inelastic structure functions F1 and FL in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q2 = 1 GeV2 in the separated structure functions independently
International Nuclear Information System (INIS)
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 FT and FL at small value of the Bjorken variable x. The parameters of the model are fitted to the HERA F2 data, and we derive a prediction for the longitudinal structure function FL. We conclude that for FL the higher twist corrections are sizable whereas for F2=FT+FL there is a nearly complete cancellation of twist-4 corrections in FT and FL. We discuss a few consequences for future LHC measurements.
Bartels, Jochen; Motyka, Leszek
2009-01-01
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 FT and FL at small value of the Bjorken variable x. The parameters of the model are fitted to the HERA F2 data, and we derive a prediction for the longitudinal structure function FL. We conclude that for FL the higher twist corrections are sizable whereas for F2 = FT + FL there is a nearly complete cancellation of twist-4 corrections in FT and FL. We discuss a few consequences for future LHC measurements.
Axial vector diquark correlations in the nucleon: structure functions and static properties
International Nuclear Information System (INIS)
In order to extract information on the strength of quark-quark correlations in the axial vector (a.v.) diquark channel (JP=1+,T=1), we analyze the quark light cone momentum distributions in the nucleon, in particular their flavor dependencies, and the static properties of the nucleon. To construct the nucleon as a relativistic 3-quark bound state, we use a simple 'static' approximation to the full Faddeev equation in the Nambu-Jona-Lasinio model, including correlations in the scalar (JP=0+,T=0) and a.v. diquark channels. It is shown that the a.v. diquark correlations should be rather weak compared to the scalar ones. From our analysis we extract information on the strength of the correlations as well as on the probability of the a.v. diquark channel
Nocera, Emanuele Roberto
2014-01-01
I investigate the behavior of spin-dependent parton distribution functions in the regions of small and large momentum fractions $x$. I present a systematic comparison between predictions for relevant observables obtained with various models of nucleon spin structure and a recent global analysis of spin-dependent distributions, NNPDFpol1.1. Together with its unpolarized counterpart, NNPDF2.3, they form a mutually consistent set of parton distributions. Because they include most of the available experimental information, and are determined with a minimally biased methodology, these are especially suited for such a study. I show how NNPDFpol1.1 can discriminate between different theoretical models, even though NNPDF uncertainties remain large near the endpoints $x\\to 0$ and $x\\to 1$, due to the lack of experimental information. I discuss how our knowledge of nucleon spin structure may be improved at small-$x$ by future measurements at an Electron-Ion Collider, and at large-$x$ by recent measurements at Jefferson...
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.
International Nuclear Information System (INIS)
The spin and flavor structure of quarks and gluons in nucleons and nuclei is more complicated than expected in the original naive quark model. Recent results which show some of the key failures of the naive picture are summarized here with emphasis on recent results from the HERMES experiment. Some future options to study the quarks structure in exclusive processes in electroproduction, photoproduction and pp annihilation are presented. (orig.)
Measurement of the nucleon g sub 2 spin structure function at SLAC
Rondon, Oscar A
1999-01-01
The deep inelastic polarized structure functions g sup p sup , sup n sub 2 and g sup p sup , sup n sub 1 have been recently measured at the Stanford Linear Accelerator Center (SLAC) End Station A facility by the E155 Collaboration using 48.4 GeV and 38.8 GeV longitudinally polarized electrons incident on longitudinally and transversely polarized ammonia (NH sub 3) and lithium deuteride ( sup 6 Li sup 2 H sub 3) targets. The proton and deuteron data are combined to extract the neutron structure functions.
Nucleon structure from stochastic estimators
Bali, Gunnar S; Gläßle, Benjamin; Göckeler, Meinulf; Najjar, Johannes; Rödl, Rudolf; Schäfer, Andreas; Sternbeck, André; Söldner, Wolfgang
2013-01-01
Using stochastic estimators for connected meson and baryon three-point functions has successfully been tried in the past years. Compared to the standard sequential source method we trade the freedom to compute the current-to-sink propagator independently of the hadron sink for additional stochastic noise in our observables. In the case of the nucleon we can use this freedom to compute many different sink-momentum/polarization combinations, which grants access to more virtualities. We will present preliminary results on the scalar, electro-magnetic and axial form factors of the nucleon in $N_f=2+1$ lattice QCD and contrast the performance of the stochastic method to the sequential source method. We find the stochastic method to be competitive in terms of errors at fixed cost.
The quark structure of the nucleons
International Nuclear Information System (INIS)
The suitableness of the non-relativistic potential model for the description of quarks in nucleons is proved and the model extensively presented. Practical applications are some contributions to the nucleon-nucleon interaction which result from the quark structure of the nucleons. These are especially the quark-gluon exchange and the quark-pion exchange between nucleons. The influences of these interactions on the s and p scattering of the nucleons are calculated in the framework of the resonating-group method. Furthermore we study the change of the quark structure if two nucleons approach very closely. The interaction of the nucleons by quark-gluon exchange causes an increase of the nucleon radius and a shift of the quark momenta to lower values. On this base the momentum distribution of quarks in nuclei is calculated and a natural explanation of the EMC effect is given. The distance distribution of nucleons and their Fermi motion are calculated for this in the shell model. Then we make further considerations in connection with the flavor symmetry, the collapse of the nucleons and the properties of six-quark bags. Altogether it is shown that in the potential model the most different effects of the quark structure of nucleons can be surprisingly well described in an illustrative way. (orig.)
International Nuclear Information System (INIS)
It is unavoidable to deal with the quark and gluon momentum and angular momentum contributions to the nucleon momentum and spin in the study of nucleon internal structure. However we never have the quark and gluon momentum, orbital angular momentum and gluon spin operators which satisfy both the gauge invariance and the canonical momentum and angular momentum commutation relation. The conflicts between the gauge invariance and canonical quantization requirement of these operators are discussed. A new set of quark and gluon momentum, orbital angular momentum and spin operators, which satisfy both the gauge invariance and canonical momentum and angular momentum commutation relation, are proposed. The key point to achieve such a proper decomposition is to separate the gauge field into the pure gauge and the gauge covariant parts. The same conflicts also exist in QED and quantum mechanics and have been solved in the same manner. The impacts of this new decomposition to the nucleon internal structure are discussed. (authors)
International Nuclear Information System (INIS)
570 000 neutrino-iron and 370 000 antineutrino-iron charged-current events were obtained from the Wide Band Beam exposure of the CDHS detector at CERN in 1983, at energies ranging from 20 to 400 GeV. These large statistics allowed a precise measurement of the charged-current differential cross-sections and a detailed study of systematic effects. The nucleon structure functions have been determined in the framework of the quark-parton model, in the kinematic range: 0.01522/c2. The longitudinal structure function FL(x) is in good agreement with the QCD predicted shape. Deviations from scale invariance are clearly seen from the functions F2 and xF3. The Q2 evolution of the valence quark distribution has been compared with the QCD prediction in order to measure the scale parameter ?. A good agreement is obtained only if the low Q2 points are removed from the comparison. Our experiment favours a value of ? between 50 and 250 MeV
Generalized sum rules for spin-dependent structure functions of the nucleon
International Nuclear Information System (INIS)
The Drell-Hearn-Gerasimov and Bjorken sum rules are special examples of dispersive sum rules for the spin-dependent structure function G1(?,Q2) at Q2=0 and ?. We generalize these sum rules through studying the virtual-photon Compton amplitudes S1(?,Q2) and S2(?,Q2). At small Q2, we calculate the Compton amplitudes at leading order in chiral perturbation theory; the resulting sum rules will be able to be tested against data soon available from the Jefferson Laboratory. For Q2>>?QCD2, the standard twist-expansion for the Compton amplitudes leads to the well known deep-inelastic sum rules. Although the situation is still relatively unclear in a small intermediate-Q2 window, we argue that chiral perturbation theory and the twist-expansion alone already provide strong constraints on the Q2-evolution of the G1(?,Q2) sum rule from Q2=0 to ?. (author)
New Results on Nucleon Spin Structure
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen
2005-09-10
Recent precision spin structure data from Jefferson Lab have significantly advanced our knowledge of nucleon structure in the valence quark (high-x) region and improved our understanding of higher-twist effects, spin sum rules and quark-hadron duality. First, results of a precision measurement of the neutron spin asymmetry, A{sub 1}{sup n}, in the high-x region are discussed. The new data shows clearly, for the first time, that A{sub 1}{sup n} becomes positive at high x. They provide crucial input for the global fits to world data to extract polarized parton distribution functions. Preliminary results on A{sub 1}{sup p} and A{sub 1}{sup d} in the high-x region have also become available. The up and down quark spin distributions in the nucleon were extracted. The results for {Delta}d/d disagree with the leading-order pQCD prediction assuming hadron helicity conservation. Then, results of a precision measurement of the g{sub 2}{sup n} structure function to study higher-twist effects are presented. The data show a clear deviation from the lead-twist contribution, indicating a significant higher-twist (twist-3 or higher) effect. The second moment of the spin structure functions and the twist-3 matrix element d{sub 2}{sup n} results were extracted at a high Q{sup 2} of 5 GeV{sup 2} from the measured A{sub 2}{sup n} in the high-x region in combination with existing world data and compared with a Lattice QCD calculation. Results for d{sub 2}{sup n} at low-to-intermediate Q{sup 2} from 0.1 to 0.9 GeV{sup 2} were also extracted from the JLab data. In the same Q{sup 2} range, the Q{sup 2} dependence of the moments of the nucleon spin structure functions was measured, providing a unique bridge linking the quark-gluon picture of the nucleon and the coherent hadronic picture. Sum rules and generalized forward spin polarizabilities were extracted and compared with Chiral Perturbation Theory calculations and phenomenological models. Finally, preliminary results on the resonance spin structure functions in the Q{sup 2} range from 1 to 4 GeV{sup 2} were presented, which, in combination with DIS data, will enable a detailed study of the quark-hadron duality in spin structure functions.
Nasseripour, R; Ambrozewicz, P; Carman, D S; Amaryan, M J; Anciant, E; Anghinolfi, M; Asavapibhop, B; Asryan, G; Audit, G; Auger, T; Avakian, H; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Battaglieri, M; Beard, K; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Blaszczyk, L; Bonner, B E; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Casey, L; Cetina, C; Chen, S; Cheng, L; Cole, P L; Collins, P; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Credé, V; Dale, D; Dashyan, N; De Masi, R; De Vita, R; De Sanctis, E; Degtyarenko, P V; Dennis, L; Deur, A; Dhuga, K S; Dickson, R; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fatemi, R; Fedotov, G; Feldman, G; Feuerbach, R J; Forest, T A; Fradi, A; Funsten, H; Garçon, M; Gavalian, G; Gevorgyan, N; Gilfoyle, G P; Giovanetti, K L; Girard, P; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hafidi, K; Hakobyan, H; Hanretty, C; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hu, J; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Jo, H S; Johnstone, J R; Joo, K; Jüngst, H G; Kalantarians, N; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Kossov, M; Krahn, Z; Kramer, L H; Kubarovski, V; Kühn, J; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Livingston, K; Lu, H Y; Lukashin, K; MacCormick, M; Manak, J J; Markov, N; Mattione, P; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Moreno, B; Moriya, K; Morrow, S A; Moteabbed, M; Müller, J; Munevar, E; Mutchler, G S; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Niyazov, R A; Nozar, M; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Anefalos Pereira, S; Peterson, G; Philips, S A; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Pozdniakov, S; Preedom, B M; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Qin, L M; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Rosner, G; Rossi, P; Rubin, P D; Sabati, F; Salamanca, J; Salgado, C; Santoro, J P; Sapunenko, V; Sayre, D; Schumacher, R A; Serov, V S; Shafi, A; Sharabyan, Yu G; Sharov, D; Shvedunov, N V; Simionatto, S; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Sokhan, D; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Tkabladze, A; Tkachenko, S; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Watts, D P; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J; Zhao, B; Zhao, Z W
2008-01-01
The first measurements of the polarized structure function $\\sigma_{LT'}$ for the reaction $p(\\vec e,e'K^+)\\Lambda$ in the nucleon resonance region are reported. Measurements are included from threshold up to $W$=2.05 GeV for central values of $Q^2$ of 0.65 and 1.00 GeV$^2$, and nearly the entire kaon center-of-mass angular range. $\\sigma_{LT'}$ is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate s-channel resonances, as well as resonant and non-resonant processes. The results for $\\sigma_{LT'}$ are comparable in magnitude to previously reported results from CLAS for $\\sigma_{LT}$, the real part of the same response. An intriguing sign change in $\\sigma_{LT'}$ is observed in the high $Q^2$ data at $W\\approx 1.9$ GeV. Comparisons to several existing model predictions are shown.
Long Range Structure of the Nucleon
Vanderhaeghen, Marc; Walcher, Thomas
2010-01-01
The long range structure of the nucleon is discussed starting from the old model of a quark bag with a pion cloud (``cloudy bag'') carrying on to the more recent ideas of the parton model of the nucleon. On the basis of the most recent measurements of the form factors at MAMI, JLab and MIT quantitative results for nucleon charge densities are presented within both non-relativistic and relativistic frameworks.
International Nuclear Information System (INIS)
In the deep inelastic neutrino scattering experiment of the CERN-Dortmund-Heidelberg-Saclay collaboration realized on the CERN SPS narrow band beam, we have measured 23000 charged current neutrino and 6200 antineutrino interactions. The structure functions of the nucleon have been extracted from the differential cross sections on iron and compared with parton model predictions. The total cross sections and the fraction of momentum carried by the antiquarks in the nucleon have been measured as function of the neutrino energy. The structure functions obtained for different Q2 bins show significant deviations from scale invariance. The data are in agreement with QCD predictions for a value of the scale parameter ? between 300 and 700 MeV
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.
Nucleon spin structure functions
International Nuclear Information System (INIS)
There has been recent excitement arising from the claim by the EMC collaboration that none of the proton's spin is carried by quarks. There are many textbooks, including those written by some members of this audience which assert that the proton's spin is carried by quarks. I will review the history of deep inelastic scattering of polarized leptons from polarized protons, culminating in this most recent dramatic claim. I will show that, for the last decade, data have appeared consistent with predictions of the quark model and highlight what the new and potentially exciting data are. I will conclude with suggestions for the future, and discuss the polarization dependence of inclusive hadron production. 35 refs
Ziaja, Beata
2002-01-01
Theoretical predictions show that at low values of Bjorken $x$ the spin structure function, $g_1$ is influenced by large logarithmic corrections, $ln^2(1/x)$, which may be predominant in this region. These corrections are also partially contained in the NLO part of the standard DGLAP evolution. Here we calculate the non-singlet component of the nucleon structure function, $g_1^{NS}=g_1^p-g_1^n$, and its first moment, using a unified evolution equation. This equation incorpor...
International Nuclear Information System (INIS)
Various aspects of nuclear physics at intermediate energies, in connection with the description of the nucleon-nucleon potential in terms of mesons, are presented in this thesis. The meson exchange current contribution is studied in the case of the deuteron (np capture and electrodisintegration near threshold). A consistent description of these processes is discussed, with particular emphasis on the effective range of the current, for momentum transfers as large as q2?1 (GeV/c)2. The structure of finite nuclei and nuclear matter is then analysed in the framework of a relativistic formalism, in which the negative energy component of the nucleon wave function is explicitly taken into account. The nuclear matter saturation mechanism is studied in details and compared with the non-relativistic limit. Properties of finite nuclei are also discussed. Finally, the structure of the nucleon itself in the nuclear medium is investigated. A connection between the polarisation of the nucleon (three valence quark component), the incompressibility parameter and the mass of the first monopole excitation of the nucleon is presented
Weak and electromagnetic probes of nucleon structure
International Nuclear Information System (INIS)
We present some highlights of recent attempts to use the electro-weak interaction to learn about the structure of the nucleon (free and bound). Particular emphasis is placed upon the role of deep-inelastic scattering
Short-range correlations of partons & 3D nucleon structure
Directory of Open Access Journals (Sweden)
Schweitzer P.
2014-03-01
Full Text Available Dynamical breaking of chiral symmetry in QCD is caused by non-perturbative interactions on a scale ? ? 0.3 fm much smaller than the hadronic size R ? 1 fm. This has important consequences for the nucleon structure such as the prediction that the transverse momentum distribution of sea quarks is significantly broader than the pT -distribution of valence quarks due to short-range correlations between sea quarks in the nucleon’s light-cone wave function.
Transverse Spin Structure of the Nucleon
Perdekamp, Matthias Grosse
2015-01-01
We review the current status and future perspectives of theory and experiments of transverse spin phenomena in high-energy scattering processes off nucleon targets and related issues in nucleon structure and QCD. Systematic exploration of transverse spin effects requires measurements in polarized deep-inelastic scattering, polarized pp collisions, and e+e- annihilations. Sophisticated QCD-based techniques are also needed to analyze the experimental data sets.
Experimental Study of Nucleon Structure and QCD
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen
2012-03-01
Overview of Experimental Study of Nucleon Structure and QCD, with focus on the spin structure. Nucleon (spin) Structure provides valuable information on QCD dynamics. A decade of experiments from JLab yields these exciting results: (1) valence spin structure, duality; (2) spin sum rules and polarizabilities; (3) precision measurements of g{sub 2} - high-twist; and (4) first neutron transverse spin results - Collins/Sivers/A{sub LT}. There is a bright future as the 12 GeV Upgrade will greatly enhance our capability: (1) Precision determination of the valence quark spin structure flavor separation; and (2) Precision extraction of transversity/tensor charge/TMDs.
Nucleon-pion-state contribution to nucleon two-point correlation functions
Bar, Oliver
2015-01-01
We study the nucleon-pion-state contribution to the QCD two-point function of the standard nucleon interpolating fields. For sufficiently small quark masses these two-particle states are expected to have a smaller total energy than the single-particle excited states. We calculate the nucleon-pion-state contribution to leading order in chiral perturbation theory. Both parity channels are considered. We find the nucleon-pion-state contribution to be small, contributing at the few percent level ...
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
International Nuclear Information System (INIS)
In this thesis the nucleon structure function xF3 is determined from the inclusive measurement of the deep inelastic neutrino nucleon charged current interaction. The data were taken in the CERN wide band neutrino beam using the detector of the CERN-Dortmund-Heidelberg-Saclay collaboration. This detector serves at the same time as target, as hadron energy calorimeter and as muon spectrometer. One major aspect of this work was to study the possibility of using high statistics wide band beam data for structure function analysis. The systematic errors specific to this kind of beam are investigated. To obtain the differential cross sections about 100000 neutrino and 75000 antineutrino events in the energy range 20-200 GeV are analysed. The differential cross sections are normalized to the total cross sections, as measured in the narrow band beam by the same collaboration. The calculated structure function xF3 shows significant deviations from scaling. These scaling violations are compared quantitatively with the predictions of quantum chromodynamics. (orig.)
Nucleon spin structure at low momentum transfers
Pasechnik, Roman; Teryaev, Oleg
2010-01-01
The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into account higher order radiative and higher twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent proton structure function $\\Gamma_1^{p}(Q^2)$ and on the Bjorken sum rule $\\Gamma_1^{p-n}(Q^2)$. By using the singularity-free analytic perturbation theory we demonstrate that the matching point between chiral-like positive-$Q^2$ expansion and QCD operator product $1/Q^2$-expansion for the nucleon spin sum rules can be shifted down to rather low $Q\\simeq\\Lambda_{QCD}$ leading to a good description of recent proton, neutron, deuteron and Bjorken sum rule data at all accessible $Q^2$.
New insights into the spin structure of the nucleon
Bernard, V; Krebs, H; Meißner, U -G
2012-01-01
We analyze the low-energy spin structure of the nucleon in a covariant effective field theory with explicit spin-3/2 degrees of freedom to third order in the small scale expansion. Using the available data on the strong and electromagnetic width of the Delta-resonance, we give parameter-free predictions for various spin-polarizabilities and moments of spin structure functions. We find an improved description of the nucleon spin structure at finite photon virtualities for some observables and point out the necessity of a fourth order calculation.
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.
Nucleon Spin Structure: Longitudinal and Transverse
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen
2011-02-01
Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction. The transverse spin structure and the TMDs are the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has played a major role in the worldwide effort to study both the longitudinal and transverse spin structure. Highlights of recent results will be presented. With 12-GeV energy upgrade, JLab will provide the most precise measurements in the valence quark region to close a chapter in longitudinal spin study. JLab will also perform a multi-dimensional mapping of the transverse spin structure and TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space and extracting the u and d quark tensor charges of the nucleon. The precision mapping of TMDs will also allow a detailed study of the quark orbital motion and its dynamics.
Nucleon structure and the chiral filter
International Nuclear Information System (INIS)
I discuss the issues of quenched gA in nuclei, pionic enhancement of nuclear electromagnetic form factors, manifestation of the anomalous Wess-Zumino term in nuclear medium, all on the same footing, in terms of the nucleon structure as 'derived' from a low-energy effective theory of QCD
Nucleon structure study by virtual Compton scattering
International Nuclear Information System (INIS)
It is proposed to study nucleon structure by virtual Compton scattering using the Hall A HRS spectrometers. This reaction is planned to be measured in the Roper resonance region and at the highest center of mass energy to observe the beginning of the hard scattering regime. (author) 25 refs.; 8 figs.; 6 tabs
A covariant model for the nucleon spin structure
Ramalho, G
2015-01-01
We present the results of the covariant spectator quark model applied to the nucleon structure function $f(x)$ measured in unpolarized deep inelastic scattering, and the structure functions $g_1(x)$ and $g_2(x)$ measured in deep inelastic scattering using polarized beams and targets ($x$ is the Bjorken scaling variable). The nucleon is modeled by a valence quark-diquark structure with $S,P$ and $D$ components. The shape of the wave functions and the relative strength of each component are fixed by making fits to the deep inelastic scattering data for the structure functions $f(x)$ and $g_1(x)$. The model is then used to make predictions on the function $g_2(x)$ for the proton and neutron.
Nucleon spin structure studies at COMPASS
Marchand, Claude
2006-01-01
One of the main goal of the COMPASS experiment at CERN is the study of the spin structure of the nucleon in DIS, by scattering 160 GeV polarized muon beam on a longitudinally (or transversely) polarized $^{6}$LiD target. Besides the scattered muon, the particles produced in the deep inelastic scattering are detected by a two stage magnetic spectrometer equipped with state of the art tracking and particle ID detectors. The emphasis of COMPASS muon program is the direct determination of the gluon polarization $\\Delta G/G$, accessed via asymmetries involving photon-gluon fusion mechanism (PGF). Both open charm production (detecting $D^{0}$’s), as well as production of hight $p_{T}$ hadron pairs are used to tag PGF. Preliminary results for $\\Delta G/G$ based on the analysis of 2002 and 2003 data are shown. In addition, improved measurement of the deuteron structure function $g^{d}_{1}$ at small $x$, as well as studies of transverse distribution functions in the deuteron by measuring Collins and Sivers azimuthal...
Non-perturbative structure of the polarized nucleon sea
Cao, Fu-Guang; Signal, A. I.
2003-01-01
We investigate the flavour and quark-antiquark structure of the polarized nucleon by calculating the parton distribution functions of the nucleon sea using the meson cloud model. We find that the SU(2) flavor symmetry in the light antiquark sea and quark-antiquark symmetry in the strange quark sea are broken, {\\it i.e.} $\\Delta\\ubar < \\Delta \\dbar$ and $\\Delta s < \\Delta \\sbar$. The polarization of the strange sea is found to be positive, which is in contradiction to previou...
International Nuclear Information System (INIS)
The results from a high statistics study of the nucleon structure function F2(x, Q2) in the kinematic range x ? 0.25 and Q2 ? 25 GeV2 are presented. The analysis is based on 1.5x106 reconstructed events recorded at beam energies of 120, 200 and 280 GeV. By comparing data taken at different beam energies, it is found that a ratio R=?L/?T=0.015±0.013 (stat.) ±0.026 (syst.) is independent of x in the range 0.25 ? x ? 0.7 and 50 GeV2 ? Q2 ? 150 GeV2. The kinematic region of these data makes them well suited for quantitative tests of quantum chromodynamics (QCD). From a next-to-leading order nonsinglet fit, a QCD mass scale parameter ?M-barS-bar=225±20 (stat.)-60+70 (syst.) MeV is founded
Wave functions of a system of three unbound interacting nucleons
International Nuclear Information System (INIS)
The equations for the wave functions of a system of three unbound interacting nucleons are obtained in the interpolation model and a method for solving them is given. Then these wave functions are found by solving the equations numerically for various spin-isospin states of the three-nucleon system for square-well nucleon potentials which depend on the spin and isospin and for some typical values of the kinematical variables. Some properties of the wave functions are discussed
Structure and Spin of the Nucleon
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut A. [JLAB
2014-03-01
Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
The nucleon spin structure in a simple quark model
Ma, B Q; Yang Jian Jun; Ma, Bo-Qiang; Schmidt, Ivan; Yang, Jian-Jun
2000-01-01
We investigate the spin structure of the nucleon in an extended Jaffe-Lipkin quark model. In addition to the conventional $3q$ structure, different $(3q)(Q\\bar{Q})$ admixtures in the nucleon wavefunction are also taken into account. The contributions to the nucleon spin from various components of the nucleon wavefunction are discussed. The effect due to the Melosh-Wigner rotation is also studied.
International Nuclear Information System (INIS)
Within the chiral bag model (CBM) the spin-dependent structure functions of a polarized proton g1p(x) and polarized neutron g1n(x) are investigated. The results obtained within CBM with a scalar Ï€qq coupling agree with EMC experimental data rather well. 11 refs.; 1 fig.; 2 tabs
Nucleon structure as a background for determination of fundamental parameters
International Nuclear Information System (INIS)
We consider deep inelastic, (quasi-) elastic lepton-nucleon scattering and investigate the possibilities of eliminating or suppressing theoretical uncertainties induced by nucleon structure in measuring the Standard Model parameters or in searching for new physics. On the basis of rather general hypothesis about nucleon structure we have obtained new relations between cross sections and neutral current parameters which are independent of the nucleon structure. We also investigate a dependence of the QCD ?-parameter extracted from the data on unknown large scale nucleon structure and propose a modification of the conventional QCD predictions which are weakly dependent of this uncertainty factor. (author). 9 refs, 1 tab
Spin structure of the nucleon at low energies
Bernard, VÃ©ronique(Institut de Physique NuclÃ©aire, CNRS/Univ. Paris-Sud 11 (UMR 8608), Orsay Cedex, F-91406, France); Hemmert, Thomas R.; MeiÃŸner, Ulf-G.
2002-01-01
The spin structure of the nucleon is analyzed in the framework of a Lorentz-invariant formulation of baryon chiral perturbation theory. The structure functions of doubly virtual Compton scattering are calculated to one-loop accuracy (fourth order in the chiral expansion). We discuss the generalization of the Gerasimov-Drell-Hearn sum rule, the Burkhardt-Cottingham sum rule and moments of these. We give predictions for the forward and the longitudinal-transverse spin polarizabilities of the pr...
Bollini, D; Benvenuti, Alberto C; Bozzo, M; Brun, R; Cvach, J; Dobrowolski, T; Fadeev, N G; Feltesse, J; Frabetti, P L; Gennow, H; Golutvin, I A; Goossens, M; Heiman, G; Jamnik, D; Kiryushin, Yu T; Kisselev, V S; Klein, M; Kopp, R; Krivokhizhin, V G; Kukhtin, V V; Maillard, J; Malasoma, J M; Meyer-Berkhout, U; Milsztajn, A; Monari, L; Navach, F; Navarria, Francesco Luigi; Nowak, Wolf-Dieter; Piemontese, L; Pilcher, J E; Renardy, J F; Sacquin, Yu; Savin, I A; Schinzel, D; Smadja, G; Smirnov, G I; Staude, A; Teichert, K M; Tirler, R; Verrecchia, P; Vesztergombi, G; Virchaux, M; Volodko, A G; Voss, R; ZÃ¡cek, J; Zupancic, Crtomir
1981-01-01
Deep inelastic scattering cross sections have been measured with the CERN SPS muon beam at incident energies of 120 and 200 GeV. Approximately 10000 events at each energy used to obtain the structure function F/sub 2/(x, Q/sup 2/) in the kinematic region 0.3
Di-hadron fragmentation and mapping of the nucleon structure
Pisano, Silvia
2015-01-01
The fragmentation of a colored parton directly into a pair of colorless hadrons is a non-perturbative mechanism that offers important insights into the nucleon structure. Di-hadron fragmentation functions can be extracted from semi-inclusive electron-positron annihilation data. They also appear in observables describing the semi-inclusive production of two hadrons in deep-inelastic scattering of leptons off nucleons or in hadron-hadron collisions. When a target nucleon is transversely polarized, a specific chiral-odd di-hadron fragmentation function can be used as the analyzer of the net density of transversely polarized quarks in a transversely polarized nucleon, the so-called transversity distribution. The latter can be extracted through suitable single-spin asymmetries in the framework of collinear factorization, thus in a much simpler framework with respect to the traditional one in single-hadron fragmentation. At subleading twist, the same chiral-odd di-hadron fragmentation function provides the cleanest...
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
Internal Spin Structure of the Nucleon in Polarized Deep Inelastic Muon-Nucleon Scattering
International Nuclear Information System (INIS)
We present the study of the internal spin structure of the nucleon in spin-dependent deep inelastic scattering of muons on nucleons. The data were taken by the NA47 experiment of the Spin Muon Collaboration (SMC) on the high energy muon beam at CERN. The experiment used the polarized proton and deuteron targets. The structure function g1p(x) and g1d(x) were determined from the asymmetries of the spin-dependent event rates in the range of 0.0032>=10 GeV2. Using the first moments of these structure functions an agreement with the Bjorken sum rule prediction was found within one standard deviation. The first moments of g1(x), for both proton and deuteron, are smaller than the Ellis-Jaffe sum rule prediction. This disagreement can be interpreted in terms of negative polarization of the strange sea in the nucleon. The singlet part of the axial current matrix element can be interpreted as an overall spin carried by quarks in the nucleon. Its value is significantly smaller than nucleon spin. Semi-inclusive asymmetries of yields of positive and negative hadrons produced on both targets were also measured and analysed in term of quark-parton model, together with inclusive asymmetries. From this analysis the quark spin distributions were determined, separately for valence u and d quarks and for non-strange sea quarks. Valence u quarks are positively polarized and their polarization increases with x. Valence d quarks are negatively polarized and their polarization does not exhibit any x-dependence. The non-strange sea is unpolarized in the whole measured range of x. The first moments of the valance quark spin distributions were found consistent with the values obtained from weak decay constants F and D and their second moments are consistent with lattice QCD calculations. In the QCD analysis of the world data the first moment of the gluon spin distribution was found with a large error. Also, a search for a non-perturbative anomaly at high x was done on the world data and the result was consistent with null. An extensive discussion of the SMC results and a comparison with results of SLAC experiment is presented. The new experiment of the COMPASS Collaboration, approved and being currently in preparation at CERN, was presented. The main physics issues of the muon part of this experiment, which are the gluon polarization and a continuation of the physics program of the SMC, were discussed. (author)
Survey of structures revealed in nucleon-nucleon scattering experiments and dibaryon resonances
International Nuclear Information System (INIS)
Structures appearing in various experimental data (particularly those with polarized beams) in nucleon-nucleon systems are reviewed. Evidence is presented for the existence of dibaryon resonances with an emphasis on a diproton resonance in 3F3 (J/sup P/ = 3-) state. 38 references
Nucleon structure study by virtual compton scattering
International Nuclear Information System (INIS)
We propose to study nucleon structure by Virtual Compton Scattering using the reaction p(e,e'p)? with the MAMI facility. We will detect the scattered electron and the recoil proton in coincidence in the high resolution spectrometers of the hall A1. Compton events will be separated from the other channels (principally ?0 production) by missing-mass reconstruction. We plan to investigate this reaction near threshold. Our goal is to measure new electromagnetic observables which generalize the usual magnetic and electric polarizabilities. (authors). 9 refs., 18 figs., 7 tabs
Nucleon-nucleon scattering in the functional quantum theory of the nonlinear spinor field
International Nuclear Information System (INIS)
The author calculates the S matrix for the elastic nucleon-nucleon scattering in the lowest approximation using the quantum theory of nonlinear spinor fields with special emphasis to the ghost configuration of this theory. Introducing a general scalar product a new functional channel calculus is considered. From the results the R and T matrix elements and the differential and integral cross sections are derived. (HSI)
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.)
A Study of Nucleon Spin Structure from Quantum Chromodynamics
Osborne, J
2001-01-01
I present an introduction to the field of Quantum Chromodynamics (QCD) with emphasis on nucleon spin structure and perturbative methods. After a somewhat comprehensive overview of perturbative QCD, including the systematics of renormalization, I introduce deeply-inelastic scattering and deeply-virtual Compton scattering along with the nonperturbative distribution functions appearing in these processes. I show how these processes can be used to extract the distribution of longitudinal spin of nucleons, and briefly discuss the complications associated with transverse spin components. There are five appendices which accompany this work, discussing topics ranging from canonical field quantization to dimensional regularization to the structure of several important Lie groups. These appendices are meant to give the reader a certain basic understanding of some of the mathematical details underlying the main text, as well as provide a useful reference. This work was submitted in a slightly different form to the Facul...
The phase-functions method and full cross-section of nucleon-nucleon scattering
Zhaba, V I
2016-01-01
For calculation of the single-channel nucleon-nucleon scattering a phase-functions method has been considered. Using a phase-functions method the following phase shifts of a nucleon-nucleon scattering are calculated numerically: nn (1S0-, 3P0-, 3P1-, 1D2-, 3F3- state), pp (1S0-, 3P0-, 3P1-, 1D2- state) and np (1S0-, 1P1-, 3P0-, 3P1-, 1D2-, 3D2- state). The calculations has been performed using realistic nucleon-nucleon potentials Nijmegen groups (NijmI, NijmII, Reid93) and potential Argonne v18. Obtained phase shifts are in good agreement with the results obtained in the framework of other methods. Using the obtained phase shifts we have calculated the full cross-section. Our results are in good agreement with those obtained by using known phases published in literature. The odds between calculations depending on a computational method of phases of scattering makes: 0,2-6,3% for pp- and 0,1-5,3% for np- scatterings (NijmI, NijmII), 0,1-4,1% for pp- and 0,1-0,4% for np- scatterings (Reid93), no more than 4,5% ...
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.
Equidistant structure and effective nucleon mass in nuclear matter
International Nuclear Information System (INIS)
The effective nucleon mass of the Equidistant Multi-Layer Structure (EMULS) is discussed self-consistently. In the density region where the Fermi gas state in nuclear matter is unstable against the density fluctuation, the EMULS gives lower binding energy. It is, however, shown that such a structure with an ordinary nucleon mass collapses due to too strong attraction. We point out that such a collapse can be avoided by taking account of an effective nucleon mass affected by the localization of nucleons. (author)
The pion-cloud contribution to the electromagnetic nucleon structure
Kupelwieser, D
2015-01-01
The present contribution continues and extends foregoing work on the calculation of electroweak form factors of hadrons using the point-form of relativistic quantum mechanics. Here we are particularly interested in studying pionic effects on the electromagnetic structure of the nucleon. To this aim we employ a hybrid constituent-quark model that comprises, in addition to the $3q$ valence component, also a $3q$+$\\pi$ non-valence component. With a simple wave function for the $3q$ component we get reasonable results for the nucleon form factors. In accordance with other authors we find that the pionic effect is significant only below $Q^2\\lesssim 0.5$~GeV$^2$.
Structure and spin of the nucleon
Directory of Open Access Journals (Sweden)
Avakian H.
2014-03-01
Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL. TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC, FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.
Nucleon spin structure I: A dynamical determination of gluon helicity distribution in the nucleon
Zhu, Wei
2015-01-01
Gluon helicity distribution in the nucleon is dynamically predicted by using a nonlinear QCD evolution equation-the DGLAP equation with the parton recombination corrections - starting from a low scale, where the nucleon is almost only consisted of valence quarks. The comparisons of our predicted gluon helicity distribution with the available data are presented. We find that the contribution of the gluon helicity to the nucleon spin structure is much larger than the predictions of most other theories. This result suggests a significant orbital angular momentum of the gluons is required to balance the gluon helicity. A novel spin-orbital structure of the proton in the light-cone frame is described based on the quantitative calculations,and the nucleon spin crisis is discussed.
Nucleon effective mass effects on the Pauli-blocking function
International Nuclear Information System (INIS)
The effects of nucleon effective mass on the Pauli-blocking function are worked out. We have shown that such effects on the quasi-deuteron mechanism of photonuclear absorption are rather relevant. The pauli-blocking function has been evaluated by applying a Monte Carlo calculation particularly suitable for simulation of intranuclear cascade process of intermediate-energy nuclear reactions. The nucleon binding in the photonuclear absorption mechanism is accordingly taken into account. (author)
Shell structures in oxygen isotopes described with modern nucleon-nucleon interactions
Fujii, S.; Okamoto, R.; Suzuki, K
2003-01-01
Shell structures in the N\\simeq Z nucleus ^{17}O and the neutron-rich oxygen isotopes ^{23}O and ^{25}O are microscopically described by calculating single-particle energies with modern nucleon-nucleon interactions within the framework of the unitary-model-operator approach. It is found that the effect of three-body cluster terms on the single-particle energy is more important in ^{23}O and ^{25}O than ^{17}O.
International Nuclear Information System (INIS)
I show that the recent precise data on the Nachtmann moments M(n,Q2) from Q2 = 3 to 40 (GeV/c)2 are extremely well represented by straight lines in the variable 1/Q2 indicating M(n,Q2) approx. equal to A0(n) + A1(n)/Q2. The threshold behaviour of the scaling function F2(x) obtained from the above ansatz, is in excellent agreement with the Drell-Yan-West relation. The predictions for M(n,Q2) for values of Q2 larger than about 200 (GeV/c)2 are quite distinct from QCD-expectations. (orig.)
The structure of the nucleon: Elastic electromagnetic form factors
International Nuclear Information System (INIS)
Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. Accurate experimental measurements of the nucleon form factors are a test-bed for understanding how the nucleon's static properties and dynamical behavior emerge from QCD, the theory of the strong interactions between quarks. There has been enormous theoretical progress, since the publication of the Jefferson Lab proton form factor ratio data, aiming at reevaluating the picture of the nucleon. We will review the experimental and theoretical developments in this field and discuss the outlook for the future. (orig.)
Nucleon wave function in the generalized Bardakci-Halpern model
International Nuclear Information System (INIS)
The generalized Bardakci-Halpern model is used to construct the nucleon wave function, which makes it possible to find the tachyon-free meson-nucleon interaction amplitudes in this model. As a consequence of the condition that the fermion spectrum contain no tachyons, together with the gauge conditions, the lightest fermion here is a fermion with the quantum numbers of the nucleon and with a squared mass which is 1.5 times larger than the square of the rho-meson mass: m2/sub N/ = (3/2)m2/sub rho/
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 ? and ? axial coupling constants are also performed for the first time in a lattice calculation, g?? = 0.441(14) and g?? -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)
Boson-exchange nucleon-nucleon potential and nuclear structure
International Nuclear Information System (INIS)
A fully momentum-dependent one-boson-exchange potential is derived which takes into account the mesons, ?, eta, sigma, rho, ? and phi. Scattering bound states and nuclear matter properties are studied in momentum space. The use of such potential is shown to be as easy as the use of more simple phenomenological interactions. In nuclear matter the formalism of Bethe-Goldstone is chosen to compute the binding energy versus density in the approximation of two-body and three-body correlations. The three-body correlated wave function obtained is then used
Nuclear energy density functional from chiral two-nucleon aaand three-nucleon interactions
Holt, J. W.; Kaiser, N.; Weise, W.
2011-10-01
An improved density-matrix expansion is used to calculate the nuclear energy density functional from chiral two- and three-nucleon interactions. The two-body interaction comprises long-range one- and two-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition we employ the leading-order chiral three-nucleon interaction with its parameters c E , c D and c 1,3,4 fixed in calculations of nuclear few-body systems. With this input the nuclear energy density functional is derived to first order in the two- and three-nucleon interaction. We find that the strength functions F ?( ?) and F so ( ?) of the surface and spin-orbit terms compare in the relevant density range reasonably with the results of phenomenological Skyrme forces. However, an improved description requires (at least) the treatment of the two-body interaction to second order. This observation is in line with the deficiencies in the nuclear matter equations of state bar E(? ) that remain in the Hartree-Fock approximation with low-momentum two- and three-nucleon interactions.
Photoproduction of nucleon resonances and their structure
International Nuclear Information System (INIS)
Review of available data on radiative decay of non-strange nucleon resonators is presented. The radiative decay amplirude values presented by different authors differ appreciably, which testifies to availability of significant systematic errors. Determination of amplitude of electric quadrupole excitation of ?33(1232) isobar and R11(1440) Roper resonance, arousing great interest due to possibilities of studying features of quark interaction in nucleons and search of hydride (quark-gluon) states, is considered in details. 87 refs.; 5 tabs
Shu, Zhan; Chen, Xiao-Lin; Deng, Wei-Zhen
2007-01-01
In $\\XQM$, a quark can emit Goldstone bosons. The flavor symmetry breaking in the Goldstone boson emission process is used to intepret the nucleon flavor-spin structure. In this paper, we study the inner structure of constituent quarks implied in $\\XQM$ caused by the Goldstone boson emission process in nucleon. From a simplified model Hamiltonian derived from $\\XQM$, the intrinsic wave functions of constituent quarks are determined. Then the obtained transition probabilities...
International Nuclear Information System (INIS)
This report covers many aspects and some of the singular events which occurred over a two year period (November 1975-November 1977) in the field of nucleonics. Tables (I-IV) include listings of new books, reviews, bibliographies, and conference proceedings. Table III, (the list of conference proceedings) is not as complete as the authors had wished because of the often-experienced long delay time between oral presentation and proceedings publication; therefore, some of the publication dates were not available. By referring to these tables, however, one can find information on almost any facet of nucleonics. According to the authors, their brief written summary emphasizes only the new, interesting, or occasionally, the peculiar aspects of the subject. Discussed are developments in radiation detectors, radiotracer techniques, nuclear archeology, growth in application of activation analysis, decay rate perturbations, and environmental concerns. 213 references
Study of excited nucleons and their structure
Energy Technology Data Exchange (ETDEWEB)
Burkert, Volker D. [JLAB, Newport News, VA (United States)
2014-01-01
Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.
Experiments on nucleon structure with neutrino and charged lepton beams
International Nuclear Information System (INIS)
Lepton scattering is the most basic tool to investigate the nucleon structure. QCD studies of the nucleon structure are an important subject. QCD is a part of standard model of particle physics but still requires careful tests both experimentally and theoretically. The quark-gluon structure of the proton and neutron has been explored by a series of deep inelastic scattering experiments with lepton beams. Neutrino scattering, with the charged current and the neutral current, provides a unique possibility to study anti-quark, strangeness and spin structure. The role of neutrino scattering, when combined with the existing and upcoming data from electron and muon scattering, is described
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.)
Modelling the nucleon wave function from soft and hard processes
Bolz, J
1996-01-01
Current light-cone wave functions for the nucleon are unsatisfactory since they are in conflict with the data of the nucleon's Dirac form factor at large momentum transfer. Therefore, we attempt a determination of a new wave function respecting theoretical ideas on its parameterization and satisfying the following constraints: It should provide a soft Feynman contribution to the proton's form factor in agreement with data; it should be consistent with current parameterizations of the valence quark distribution functions and lastly it should provide an acceptable value for the \\jp \\to N \\bar N decay width. The latter process is calculated within the modified perturbative approach to hard exclusive reactions. A simultaneous fit to the three sets of data leads to a wave function whose x-dependent part, the distribution amplitude, shows the same type of asymmetry as those distribution amplitudes constrained by QCD sum rules. The asymmetry is however much more moderate as in those amplitudes. Our distribution ampl...
The spin structure of the nucleon
International Nuclear Information System (INIS)
The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*?? + ?g + Lq + Lg where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and Lq and Lg are the orbital momentum of the quark and the gluon respectively. The ?? contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization ?g/g and the so-called transversity. (A.C.)
Spin structure of nucleon in QCD: inclusive and exclusive processes
International Nuclear Information System (INIS)
There are two basically independent ways to describe the nucleon spin structure. One is related to quark and gluon spins and another one to their total angular momenta. The latter spin structure may be studied, in principle, in hard exclusive processes
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.)
Nucleon spin structure at low momentum transfers
Pasechnik, Roman; Soffer, Jacques; Teryaev, Oleg,
2010-01-01
The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into account higher order radiative and higher twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent proton structure function $\\Gamma_1^{p}(Q^2)$ and on the Bjorken sum rule $\\Gamma_1^{p-n}(Q...
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.
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.
International Nuclear Information System (INIS)
The possibility of analyzing the mesonic structure of the nucleon by studying the quasielastic knockout of pions from nucleons is discussed. In the region where the pole approximation is applicable, the cross section for the exclusive electroproduction of a pion on a nucleon can be represented in a form that involves the momentum distribution of pions in the channel p?n+?+ (quasielastic knockout). This distribution is extracted from experimental data and is consistent with the wave function of a bound pion in the nucleon as given by the potential of ?N scattering. The spectroscopic factor Sn?(p) (this is the normalization of the momentum distribution, the number of mesons in a given channel) is estimated. A wide set of accessible, albeit as-yet-unexplored, fundamental features of the nucleon, such as the momentum distributions and spectroscopic factors in various channels (p?B+?, ?+K, etc.), can extend our knowledge about the structure of the nucleon, thereby furnishing information necessary for further development of nonperturbative QCD
About Anomalous Magnetic Moment and Structure of Nucleon
Kopylov, A V
1999-01-01
The comparison of magnetic moments of neutron and proton enables to outline qualitatively the structure of nucleon by using a model similar to the one suggested by Ida and Kobayashi that "baryons consist of a qq pair (or diquark) and another quark moving around it with orbital angular momentum L"
About Anomalous Magnetic Moment and Structure of Nucleon
Kopylov, A. V.
1999-01-01
The comparison of magnetic moment of neutron and proton enables to outline qualitatively the structure of nucleon by using a model similar to the one suggested by Ida and Kobayashi that "baryons consist of a qq pair (or a diquark) and another quark moving around it with orbital angular momentum L".
International Nuclear Information System (INIS)
Nucleon-nucleon interactions are at the heart of nuclear physics, bridging the gap between QCD and the effective interactions appropriate for the shell model. We discuss the current status of NN data sets, partial-wave analyses, and some of the issues that go into the construction of potential models. Our remarks are illustrated by reference to the Argonne v18 potential, one of a number of new potentials that fit elastic nucleon-nucleon data up to 350 MeV with a ?2 per datum near 1. We also discuss the related issues of three-nucleon potentials, two-nucleon charge and current operators, and relativistic effects. We give some examples of calculations that can be made using these realistic descriptions of NN interactions. We conclude with some remarks on how our empirical knowledge of NN interactions may help constrain models at the quark level, and hence models of nucleon structure
Model independent study of the Dirac structure of the nucleon-nucleon interaction
Plohl, O; Van Dalen, E N E
2006-01-01
Relativistic and non-relativistic modern nucleon-nucleon potentials are mapped on a relativistic operator basis using projection techniques. This allows to compare the various potentials at the level of covariant amplitudes were a remarkable agreement is found. In nuclear matter large scalar and vector mean fields of several hundred MeV magnitude are generated at tree level. This is found to be a model independent feature of the nucleon-nucleon interaction.
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)
Nucleon and pion distribution functions in the valence region
International Nuclear Information System (INIS)
An experimental and theoretical perspective is provided on the behavior of unpolarized distribution functions for the nucleon and pion on the valence-quark domain, namely, Bjorken x(greater-or-similar sign)0.4. This domain is a 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. The focus is on experimental extractions of distribution functions via electron and muon inelastic scattering, and from Drell-Yan interactions; and on theoretical treatments that emphasize an explanation of the distribution functions, providing an overview of major contemporary approaches and issues. Valence-quark physics is a compelling subject, which probes at the heart of our understanding of the standard model. There are numerous outstanding and unresolved challenges, which experiment and theory must confront. In connection with experiment, an explanation that an upgraded Jefferson Laboratory facility is well suited to provide new data on the nucleon is provided, while a future electron-ion collider could provide essential new data for the mesons. There is also great potential in using Drell-Yan interactions, at FNAL, CERN, J-PARC, and GSI, to push into the large-x domain for both mesons and nucleons. Furthermore, it is argued that explanation, in contrast to modeling and parametrization, requires a widespread acceptance of the need to adapt theory: to the lessons learnt already from the methods of nonperturbative quantum-field theory and a fuller exploitation of those methods.
Mapping High x Structure of the Nucleon: which data is missing?
International Nuclear Information System (INIS)
The analysis of numerous experiments on lepton-nucleon and lepton-nucleus deep inelastic scattering reveals several non-trivial features of the nucleon structure, which are particularly interesting in the range of large Bjorken x (x > 0.8). It is shown that new data form the lightest nuclei can provide decisive information needed for the understanding of the nucleon structure
On the structure of the nucleon optical potential
International Nuclear Information System (INIS)
The structure of the nucleon generalized optical potential (GOP) is investigated in the framework of Green's function (GF) theory. First an exact relation between its imaginary part and the total reaction cross section is derived. In the second part the GOP is decomposed using a kind of projection formalism which enables to couple in the continuum in successive steps. This is achieved by splitting up the one particle GF into a discrete and a continuous part and by summing up all contributions to the GOP containing a given number n >= 0 continuum propagators. Three expressions are extracted corresponding to different processes involving the scattering of at most two particles in the continuum in intermediate states. The remaining terms are argued to be small. Further support for retaining only the above three terms is given by evaluating the diagonal element of their imaginary part between the exact eigenstates of the GOP. This is shown to be approximately proportional to the sum of the total inelastic, charge exchange, pick-up and knock-out cross sections. The corresponding matrix element of the exact potential is proportional to the total reaction cross section. (orig.)
Nuclear energy density functional from chiral pion-nucleon dynamics
International Nuclear Information System (INIS)
We use a recently improved density-matrix expansion (B. Gebremariam, T. Duguet, S.K. Bogner, nucl-th:0910.4979) to calculate the nuclear energy density functional in chiral perturbation theory. Our calculation treats systematically the effects from 1Ï€-exchange, iterated 1Ï€-exchange, and irreducible 2Ï€-exchange with intermediate Î”-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass M*(Ï) is identical to the one of Fermi-liquid theory. The strength Fâˆ‡(Ï) of the (vector âˆ‡Ï)2 surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region Ï0/2 0. The spin-orbit coupling strength Fso(Ï) receives contributions from iterated 1Ï€-exchange (of the ''wrong sign'') and from three-nucleon interactions mediated by 2Ï€-exchange with virtual Î”-excitation (of the ''correct sign''). In the region around Ï0/2 â‰…0.08 fm-3 where the spin-orbit interaction in nuclei gains most of its weight these two components tend to cancel, thus leaving all room for the short-range spin-orbit interaction. The strength function FJ(Ï) multiplying the squared spin-orbit density vector J2 is also studied.
Feasibility studies for nucleon structure measurements with PANDA
Atomssa, Ermias; Ma, Binsong
2014-11-01
The study of nucleon structure is one of the main physics goals of PANDA to be built at the FAIR accelerator complex. The excellent particle identification performance of the PANDA detector will enable measurements of exclusive channels p¯ p ? e+e- and p¯ p ? ?0 J/? ? ?0e+e- to extract the electromagnetic form factors of protons and ?-nucleon Transition Distribution Amplitudes (?-N TDAs). After a brief description of the PANDA apparatus and a method to handle momentum resolution degradation due to Bremsstrahlung, the physics of ?-N TDAs is discussed. An estimate for the expected signal to background ratio for p¯ p ? ?0 J/? ? ?0e+e- that takes into account the main background source is given.
The triton binding energy and the nd-scattering lengths with account of a quark nucleon structure
International Nuclear Information System (INIS)
A simple model for the nucleon-nucleon interaction is suggested which takes into account the quark nucleon structure. Using this model the triton binding energy and the nd-scattering lengths are calculated
Wakamatsu, M.
2014-08-01
It is now widely recognized that a key to unraveling the nonperturbative chiral dynamics of QCD hidden in the deep-inelastic-scattering observables is the flavor structure of sea-quark distributions in the nucleon. We analyze the flavor structure of the nucleon sea in both the unpolarized and longitudinally polarized parton distribution functions within the flavor SU(3) chiral quark-soliton model, which contains only one adjustable parameter, ?ms, the effective mass difference between the strange and nonstrange quarks. Particular attention is paid to a nontrivial correlation between the flavor asymmetry of the unpolarized and longitudinally polarized sea-quark distributions and also to a possible particle-antiparticle asymmetry of the strange-quark distributions in the nucleon. We also investigate the charge-symmetry-violation effects in the parton distribution functions exactly within the same theoretical framework, which is expected to provide us with valuable information on the relative importance of the asymmetry of the strange and antistrange distributions and the charge-symmetry-violation effects in the valence-quark distributions inside the nucleon in the resolution scenario of the so-called NuTeV anomaly in the extraction of the Weinberg angle.
$q \\to \\Lambda$ Fragmentation Function and Nucleon Transversity Distribution in a Diquark Model
Yang Jian Jun
2002-01-01
Based on a simple quark-diquark model, we propose a set of unpolarized, longitudinally polarized and transversely polarized fragmentation functions for the $\\Lambda$ by fitting the unpolarized $\\Lambda$ production data in $e^+ e ^- $ annihilation. It is found that the helicity structure of the obtained $\\Lambda$ fragmentation functions is supported by the all available experimental data on the longitudinal $\\Lambda$ polarization. Within the same framework of the diquark model, the nucleon transversity distributions are presented and consistent descriptions of the available HERMES data on the azimuthal spin asymmetries in pion electroproduction are obtained. Furthermore, the spin transfers to the transversely polarized $\\Lambda$ in the charged lepton DIS on a transversely polarized nucleon target are predicted for future experiments.
q{yields}{lambda} fragmentation function and nucleon transversity distribution in a diquark model
Energy Technology Data Exchange (ETDEWEB)
Yang, Jian-Jun E-mail: jjyang@fis.utfsm.cl
2002-03-11
Based on a simple quark-diquark model, we propose a set of unpolarized, longitudinally polarized and transversely polarized fragmentation functions for the {lambda} by fitting the unpolarized {lambda} production data in e{sup +}e{sup -} annihilation. It is found that the helicity structure of the obtained {lambda} fragmentation functions is supported by the all available experimental data on the longitudinal {lambda} polarization. Within the same framework of the diquark model, the nucleon transversity distributions are presented and consistent descriptions of the available HERMES data on the azimuthal spin asymmetries in pion electroproduction are obtained. Furthermore, the spin transfers to the transversely polarized {lambda} in the charged-lepton DIS on a transversely polarized nucleon target are predicted for future experiments.
Nucleon Polarizabilities from Deuteron Compton Scattering within a Green's-Function Hybrid Approach
Hildebrandt, R P; Hemmert, T R; Griesshammer, Harald W.; Hemmert, Thomas R.; Hildebrandt, Robert P.
2005-01-01
We examine elastic Compton scattering from the deuteron for photon energies ranging from zero to 100 MeV, using state-of-the-art deuteron wave functions and NN-potentials. Nucleon-nucleon rescattering between emission and absorption of the two photons is treated by Green's functions in order to ensure gauge invariance and the correct Thomson limit. With this Green's-function hybrid approach, we fulfill the low-energy theorem of deuteron Compton scattering and there is no significant dependence on the deuteron wave function used. Concerning the nucleon structure, we use Chiral Effective Field Theory with explicit \\Delta(1232) degrees of freedom within the Small Scale Expansion up to leading-one-loop order. Agreement with available data is good at all energies. Our 2-parameter fit to all elastic $\\gamma d$ data leads to values for the static isoscalar dipole polarizabilities which are in excellent agreement with the isoscalar Baldin sum rule. Taking this value as additional input, we find \\alpha_E^s= (11.3+-0.7...
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 Î›, at next to leading order: hydrogen target: Î›sub(MS) = 139(+170-100)MeV; iron target: Î›sub(MS) = 170(+160-100)MeV we have performed a study of the 1/Q2 effects on the Q2 domain covered by SLAC and E.M.C. We have extracted the ratio R = sigma sub(L)/sigma sub(T) for various chi bins and compared it with other experimental values and theoretical predictions. The mean value = 0+-.15 was found and is compatible with zero
Studies of nucleon resonance structure in exclusive meson electroproduction
International Nuclear Information System (INIS)
Studies of the structure of excited baryons are key factors to the N* program at Jefferson Lab (JLab). Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electroproduction off protons, along with Quantum Chromodynamics (QCD)-based approaches to the theoretical interpretation of these fundamental quantities. This program will afford access to the dynamics of the nonperturbative strong interaction responsible for resonance formation, and will be crucial in understanding the nature of confinement and dynamical chiral symmetry breaking in baryons, and how excited nucleons emerge from QCD. (author)
Off-shell electron-nucleon cross section and quasielastic response functions RL and RT
International Nuclear Information System (INIS)
A new reduced version of the relativistic half off-shell virtual photon-nucleon vertex is suggested. The gauge invariance, on-shell condition and bound Dirac equation for initial nucleon state are used. Using this vertex, the quasielastic response functions RL and RT for medium heavy nuclei are evaluated and compared with the experimental data. The off-shell electron-nucleon cross section is also calculated and compared with other off-shell extrapolation. (author)
Polarized lepton-nucleon scattering
International Nuclear Information System (INIS)
Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions
Contribution of nucleon-nucleon correlations to the EMC effect
International Nuclear Information System (INIS)
Quark momentum distributions in nuclei are calculated by solving for the nucleon-nucleon scattering in the nucleus a generalized Bethe-Goldstone equation with quark degrees of freedom in a nonrelativistic quark model, including Pauli blocking due to other nucleons and six-quark bags with different radii. The structure functions of a nucleon in /sup 56/Fe and /sup 107/Ag are calculated. The largest part of the EMC effect is explained by binding of the single nucleons. But the short range correlations including six-quark bags give the important contributions to explain details and the A-dependence of the EMC effect
Energy Technology Data Exchange (ETDEWEB)
Wiringa, R.B.
1996-12-31
Nucleon-nucleon interactions are at the heart of nuclear physics, bridging the gap between QCD and the effective interactions appropriate for the shell model. We discuss the current status of {ital NN} data sets, partial-wave analyses, and some of the issues that go into the construction of potential models. Our remarks are illustrated by reference to the Argonne {ital v}{sub 18} potential, one of a number of new potentials that fit elastic nucleon-nucleon data up to 350 MeV with a {Chi}{sup 2} per datum near 1. We also discuss the related issues of three-nucleon potentials, two-nucleon charge and current operators, and relativistic effects. We give some examples of calculations that can be made using these realistic descriptions of {ital NN} interactions. We conclude with some remarks on how our empirical knowledge of {ital NN} interactions may help constrain models at the quark level, and hence models of nucleon structure.
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 â†’ e{sup +}e{sup -} by means of two factorization approaches. These corrections are found to be smaller than those obtained for the spacelike scattering process. The influence of the two-photon exchange corrections on cross section measurements as well as asymmetries, which allow a direct access of the two-photon exchange contribution, is discussed. Furthermore, one of the factorization approaches is applied for investigating the two-boson exchange effects in parity-violating electron-proton scattering. In the last part of the underlying work, the process p anti pâ†’Ï€{sup 0}e{sup +}e{sup -} is analyzed with the aim of determining the form factors in the so-called unphysical, timelike region below the two-nucleon production threshold. For this purpose, a phenomenological model is used, which provides a good description of the available data of the real photoproduction process p anti pâ†’>Ï€{sup 0}Î³.
Nucleon electromagnetic structure studies in the spacelike and timelike regions
International Nuclear Information System (INIS)
The thesis investigates the nucleon structure probed by the electromagnetic interaction. One of the most basic observables, reflecting the electromagnetic structure of the nucleon, are the form factors, which have been studied by means of elastic electron-proton scattering with ever increasing precision for several decades. In the timelike region, corresponding with the proton-antiproton annihilation into a electron-positron pair, the present experimental information is much less accurate. However, in the near future high-precision form factor measurements are planned. About 50 years after the first pioneering measurements of the electromagnetic form factors, polarization experiments stirred up the field since the results were found to be in striking contradiction to the findings of previous form factor investigations from unpolarized measurements. Triggered by the conflicting results, a whole new field studying the influence of two-photon exchange corrections to elastic electron-proton scattering emerged, which appeared as the most likely explanation of the discrepancy. The main part of this thesis deals with theoretical studies of two-photon exchange, which is investigated particularly with regard to form factor measurements in the spacelike as well as in the timelike region. An extraction of the two-photon amplitudes in the spacelike region through a combined analysis using the results of unpolarized cross section measurements and polarization experiments is presented. Furthermore, predictions of the two-photon exchange effects on the e+p/e-p cross section ratio are given for several new experiments, which are currently ongoing. The two-photon exchange corrections are also investigated in the timelike region in the process p anti p ? e+e- by means of two factorization approaches. These corrections are found to be smaller than those obtained for the spacelike scattering process. The influence of the two-photon exchange corrections on cross section measurements as well as asymmetries, which allow a direct access of the two-photon exchange contribution, is discussed. Furthermore, one of the factorization approaches is applied for investigating the two-boson exchange effects in parity-violating electron-proton scattering. In the last part of the underlying work, the process p anti p??0e+e- is analyzed with the aim of determining the form factors in the so-called unphysical, timelike region below the two-nucleon production threshold. For this purpose, a phenomenological model is used, which provides a good description of the available data of the real photoproduction process p anti p?>?0?.
Nuclear structure functions and QCD
International Nuclear Information System (INIS)
It is shown that QCD evolution equations lead, for high-Q2 nuclear structure functions, to a convolution form with additional collective quark and gluon seas. Classes of models are confronted with this point of view, and it is shown that none of the nucleon models seems satisfactory and the presence of multiquark states seems unavoidable even in the region of x < 1
Shell-structure influence on the multinucleon transfer in nucleon transfer matrix elements
International Nuclear Information System (INIS)
An analysis of the experimental data on the charge (mass) distributions of products in nuclear reactions with heavy ions [1], dependence of yield of fragments on their isotope numbers and ones of projectile- and target nuclei [2], and cross sections of the formation of evaporation residues at synthesis of new superheavy elements [3] shows that the individual peculiarities (shell structure, N/Z-ratio) of interacting nuclei play decisive role at formation and evolution of dinuclear system. Therefore, the appropriate microscopic model should be used for the theoretical analysis of the above mentioned effects. The main quantities which must be included into model are the realistic scheme of single-particle states, nucleon separation energy, single-particle matrix elements of nucleon transitions in nuclei and nucleon exchange between them caused by influence of the mean-field of partner-nucleus. In this work the nucleon transfer matrix elements were calculated for the Wood-Saxon potential for spherical nucleus. The eigenvalues and wave functions of single-particle states were obtained by numerical solving Schroedinger's equation. The integral estimation of the matrix elements is found by comparing the calculated width of the charge distributions of the reaction products with the experimental data. In the early paper [4], the same matrix elements were calculated analytically using an approximation for wave functions: authors have used wave functions of the spherical potential well. The numerical values of squares of proton transfer matrix elements found in this work are nearly in coincidence with that presented in [4]. There is a difference between curves of dependencies of the matrix elements under discussion on the relative distance between centres of nuclei when this distance is smaller than sum of nuclei radii. (author)
Shell-structure influence on the multinucleon transfer in nucleon transfer matrix elements
International Nuclear Information System (INIS)
Full text: An analysis of the experimental data on the charge (mass) distributions of products in nuclear reactions with heavy ions [1], dependence of yield of fragments on their isotope numbers and ones of projectile- and target nuclei [2], and cross sections of the formation of evaporation residues at synthesis of new superheavy elements [3] shows that the individual peculiarities (shell structure, N/Z-ratio) of interacting nuclei play decisive role at formation and evolution of dinuclear system. Therefore, the appropriate microscopic model should be used for the theoretical analysis of the above mentioned effects. The main quantities which must be included into model are the realistic scheme of single-particle states, nucleon separation energy, single-particle matrix elements of nucleon transitions in nuclei and nucleon exchange between them caused by influence of the mean-field of partner-nucleus. In this work the nucleon transfer matrix elements were calculated for the Wood-Saxon potential for spherical nucleus. The eigenvalues and wave functions of single-particle states were obtained by numerical solving Schroedinger's equation. The integral estimation of the matrix elements is found by comparing the calculated width of the charge distributions of the reaction products with the experimental data. In the early paper [4], the same matrix elements were calculated analytically using an approximation for wave functions: authors have used wave functions of the spherical potential well. The numerical values of squares of proton transfer matrix elements found in this work are nearly in coincidence with that presented in [4]. There is a difference between curves of dependencies of the matrix elements under discussion on the relative distance between centres of nuclei when this distance is smaller than sum of nuclei radii
The meson polarized distribution function and mass dependence of the nucleon parton densities
Mirjalili, A
2014-01-01
The polarized distribution functions of mesons, including pion, kaon and eta, using the proton structure function, are calculated. We are looking for a relationship between the polarized distribution of mesons and the polarized structure of nucleons. We show that the meson polarized parton distributions leads to zero total spin for the concerned mesons, considering the orbital angular momentum of quarks and gluons inside the meson. Two separate Monte Carlo algorithms are applied to compute the polarized parton distributions of the kaon. Via the mass dependence of quark distributions, the distribution function of the eta meson is obtained. A new method by which the polarized sea quark distributions of protons are evolved separately -- which cannot be performed easily using the standard solution of DGLAP equations -- is introduced. The mass dependence of these distributions is obtained, using the renormalization group equation which makes their evolutions more precise. Comparison between the evolved distributio...
Nonequilibrium distribution functions of nucleons in relativistic nucleus-nucleus collisions
Directory of Open Access Journals (Sweden)
D. Anchishkin
2013-03-01
Full Text Available The collision smearing of the nucleon momenta about their initial values during relativistic nucleus-nucleus collisions is investigated. To a certain degree, our model belongs to the transport type, and we investigate the evolution of the nucleon system created at a nucleus-nucleus collision. However, we parameterize this development by the number of collisions of every particle during evolution rather than by the time variable. It is assumed that the group of nucleons which leave the system after the same number of collisions can be joined in a particular statistical ensemble. The nucleon nonequilibrium distribution functions are derived which depend on a certain number of collisions of a nucleon before a freeze-out.
What the lattice can tell us about nucleon structure
Schroers, Wolfram
2005-01-01
This review focuses on the current status of lattice calculations of three observables which are both phenomenologically and experimentally relevant and have been scrutinized recently. These three observables are the nucleon electromagnetic form factors, the momentum fraction, , and the nucleon axial coupling, gA.
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...
Szczurek, A
1999-01-01
The experimental information on nucleon production in lepton deep inelastic scattering (DIS) is rather scarce. Recently there is a growing interest in understanding the mechanism of the production of baryons in DIS, stimulated by recent results on leading protons and neutrons from electron-proton scattering at HERA. I review on different peripheral mechanisms of nucleon (proton or neutron) production in lepton DIS and discuss their role in understanding the spectra of nucleons for both fixed target and collider experiments. In DIS ep to e'Xh, the QCD hardness scale gradually diminishes from the hard scale, Q/sup 2/, in the virtual photon (current) fragmentation region to the soft, hadronic, scale in the proton (target) fragmentation region. This suggests a similarity of the inclusive spectra of leading protons and neutrons, h=p, n, in high energy hadron-proton collisions and in lepton DIS at small Bjorken-x. The semi-inclusive cross section for production of slow protons in charged-current deep inelastic (ant...
Relationship between Feshbach's and Green's function theories of the nucleon-nucleus mean field
International Nuclear Information System (INIS)
We clarify the relationship and difference between theories of the optical-model potential which had previously been developed in the framework of Feshbach's projection operator approach to nuclear reactions and of Green's function theory, respectively. For definiteness, we consider the nucleon-nucleus system but all results can readily be adapted to the atomic case. The effects of antisymmetrization are properly taken into account. It is shown that one can develop along closely parallel lines the theories of open-quotes holeclose quotes and open-quotes particleclose quotes mean fields. The open-quotes holeclose quotes one-body Hamiltonians describe the single-particle properties of the system formed when one nucleon is taken away from the target ground state, for instance in knockout of pickup processes. The particle one-body Hamiltonians are associated with the system formed when one nucleon is elastically scattered from the ground state, or is added to it by means of stripping reactions. An infinite number of particle, as well as of hole, Hamiltonians are constructed which all yield exactly the same single-particle wave functions. Many open-quotes equivalentclose quotes one-body Hamiltonians can coexist because these operators have a complicated structure: they are nonlocal, complex, and energy-dependent. They do not have the same analytic properties in the complex energy plane. Their real and imaginary parts fulfill dispersion relations which may be different. It is shown that hole and particle Hamiltonians can also be constructed by decomposing any vector of the Hilbert space into two parts which are not orthogonal to one another, in contrast to Feshbach's original theory; one interest of this procedure is that the construction and properties of the corresponding hole Hamiltonian can be justified in a mathematically rigorous way. We exhibit the relationship between the hole and particle Hamiltonians and the open-quotes mass operator.close quotes
Influence of the nucleon spectral function in photon and electron induced reactions on nuclei
International Nuclear Information System (INIS)
We study the influence of the nucleon spectral function on ? photoproduction and electroproduction on nuclei. Besides kinematical effects due to ground state correlations, also a modification of the S11(1535) decay width is taken into account, which is caused by the possible decay into nucleons with mass smaller than the pole mass in the medium. Hence, resonances with masses below the free N? threshold can contribute to ? production
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...
International Nuclear Information System (INIS)
We have performed a separation of the longitudinal and transverse structure functions for the 40Ca(e,e'p)39K reaction in the quasi-elastic region. Their ratio (L/T) is found reduced by about 30% from the Distorted Wave Impulse Approximation prediction. This result is compatible with the quenching of the Coulomb Sum-Rule observed in the inclusive ee' reaction. Since a possible swelling of the nucleon in nuclear matter has been advocated to explain this quenching, we have also measured the q-dependence of both structure functions to test this hypothesis. The results are not in favour of a large modification of the electromagnetic radius of the nucleon. From the transverse component, an upper limit of 5% can be derived for a possible increase of the radius
The controversial role of strangeness in the spin structure of the nucleon
International Nuclear Information System (INIS)
Although the strangeness content of the nucleon is small, it has played a major role in provoking puzzles and controversies in our understanding of the internal structure of the nucleon, particularly as concerns the spin structure. We recall the role of the strange polarization in precipitating the ''spin crisis in the parton model'' and discuss our present knowledge of the shape and sign of ?s(x). (orig.)
Relationship between Feshbach's and Green's function theories of the nucleon-nucleus mean field
International Nuclear Information System (INIS)
We clarify the relationship and difference between theories of the optical-model potential which had previously been developed in the framework of Feshbach's projection operator approach to nuclear reactions and of Green's function theory, respectively. For definiteness, we consider the nucleon-nucleus system but all results can readily be adapted to the atomic case. The effects of antisymmetrization are properly taken into account. It is shown that one can develop along closely parallel lines the theories of 'hole' and 'particle' mean fields. The hole one-body Hamiltonians describe the single-particle properties of the system formed when one nucleon is taken away from the target ground state, for instance in knockout or pickup processes. The particle one-body Hamiltonians are associated with the system formed when one nucleon is elastically scattered from the ground state, or is added to it by means of stripping reactions. An infinite number of particle, as well as of hole, Hamiltonians are constructed which all yield exactly the same single-particle wave functions. Many 'equivalent' one-body Hamiltonians can coexist because these operators have a complicated structure: they are nonlocal, complex, and energy-dependent. They do not have the same analytic properties in the complex energy plane. Their real and imaginary parts fulfill dispersion relations which may be different. It is shown that hole and particle Hamiltonians can also be constructed by decomposing any vector of the Hilbert space into two parts which are not orthogonal to one another, in contrast to Feshbach's original theory; one interest of this procedure is that the construction and properties of the corresponding hole Hamiltonian can be justified in a mathematically rigorous way. We exhibit the relationship between the hole and particle Hamiltonians and the 'mass operator'. The latter is associated to the time-ordered Green's function, rather than to its advanced and retarded parts separately as the hole and particle Hamiltonians. Similarities and differences between the hole and particle Hamiltonians and the mass operator are exhibited by constructing their explicit expressions in the case of nuclear matter, in the framework of second-order perturbation theory. Particular attention is paid to the connection of the mass operator and the various hole and particle Hamiltonians with observables which can be extracted from stripping, pickup and knockout reactions, in particular the spectroscopic factors and the spectral function. Since many different one-body Hamiltonians exist which all yield the same single-particle wave functions, their relative merits and drawbacks need to be discussed, with particular attention to their relationship to empirical shell- and optical-model potentials and to the possibility of developing practical approximation schemes
The role of nucleon structure in finite nuclei
International Nuclear Information System (INIS)
The quark-meson coupling model, based on a mean field description of non-overlapping nucleon bags bound by the self-consistent exchange of ?, ? and ? mesons, is extended to investigate the properties of finite nuclei. Using the Born-Oppenheimer approximation to describe the interacting quark-meson system, we derive the effective equation of motion for the nucleon, as well as the self-consistent equations for the meson mean fields. The model is first applied to nuclear matter, after which we show some initial results for finite nuclei. (orig.)
International Nuclear Information System (INIS)
We address and solve the long-standing gauge-invariance problem of the nucleon spin structure. Explicitly gauge-invariant spin and orbital angular momentum operators of quarks and gluons are obtained. This was previously thought to be an impossible task and opens a more promising avenue towards the understanding of the nucleon spin. Our research also justifies the traditional use of the canonical, gauge-dependent angular momentum operators of photons and electrons in the multipole-radiation analysis and labeling of atomic states and sheds much light on the related energy-momentum problem in gauge theories, especially in connection with the nucleon momentum
Nucleon structure with pion clouds in a flux-tube quark model
International Nuclear Information System (INIS)
Nucleon structure with pion clouds is studied in the framework of a flux-tube quark model. The meson clouds are produced by breaking flux tubes in the nucleon; then a baryon is described by three valence quarks connected by color fields and other configurations including sea quarks. These sea quarks (or meson clouds) generate baryon decay widths and shift their masses; therefore, the hadron spectroscopy in constitutent-quark models should be investigated again by including these mass shifts. In this flux-tube model, the Yukawa potential is explained by a piece of the flux tube breaking off from a nucleon and attaching itself to the other
Nuclear energy density functional from chiral two- and three-nucleon interactions
Holt, J W; Weise, W
2011-01-01
An improved density-matrix expansion is used to calculate the nuclear energy density functional from chiral two- and three-nucleon interactions. The two-body interaction comprises long-range one- and two-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition we employ the leading order chiral three-nucleon interaction with its parameters $c_E, c_D$ and $c_{1,3,4}$ fixed in calculations of nuclear few-body systems. With this input the nuclear energy density functional is derived to first order in the two- and three-nucleon interaction. We find that the strength functions $F_\
Nucleon Structure from Lattice QCD Using a Nearly Physical Pion Mass
Green, J R; Krieg, S; Negele, J W; Pochinsky, A V; Syritsyn, S N
2012-01-01
We report the first lattice QCD calculation using the almost physical pion mass mpi=149 MeV that agrees with experiment for four fundamental isovector observables characterizing the gross structure of the nucleon: the Dirac and Pauli radii, the magnetic moment, and the quark momentum fraction. The key to this success is excluding the contributions of excited states. An analogous calculation of the nucleon axial charge governing beta decay fails to agree with experiment, and we discuss possible sources of error.
Nucleon structure in terms of OPE with non-perturbative Wilson coefficients
International Nuclear Information System (INIS)
Lattice calculations could boost our understanding of Deep Inelastic Scattering by evaluating moments of the Nucleon Structure Functions. To this end we study the product of electromagnetic currents between quark states. The Operator Product Expansion (OPE) decomposes it into matrix elements of local operators (depending on the quark momenta) and Wilson coefficients (as functions of the larger photon momenta). For consistency with the matrix elements, we evaluate a set of Wilson coefficients non-perturbatively, based on propagators for numerous momentum sources, on a 243 x 48 lattice. The use of overlap quarks suppresses unwanted operator mixing and lattice artifacts. Results for the leading Wilson coefficients are extracted by means of Singular Value Decomposition. (orig.)
Nucleon structure from 2+1f dynamical DWF lattice QCD at nearly physical pion mass
Ohta, Shigemi
2011-01-01
Current status of nucleon structure calculations with joint RBC and UKQCD 2+1-flavor dynamical domain-wall fermions (DWF) lattice QCD is reported: Two ensembles with pion mass of about (m_\\pi=170) MeV and 250 MeV are used. The lattice cutoff is set at about 1.4 GeV, allowing a large spatial volume of about (L=4.6) fm across while maintaining a sufficiently small residual breaking of chiral symmetry with the dislocation-suppressing-determinant-ratio (DSDR) gauge action. We calculate all the isovector form factors and some low moments of isovector structure functions. We confirm the finite-size effect in isovector axialvector-current form factors, in particular the deficit in the axial charge and its scaling in terms of (m_\\pi L), that we reported from our earlier calculation at heavier pion masses.
Pion and nucleon structure as probed in the reaction ?/sup +-/N ? ?+?-X at 253 GeV
International Nuclear Information System (INIS)
New results are presented from Fermilab experiment E615, in which hadroproduction of muon pairs allows a determination of the quark structure of the initial-state hadrons in the context of a Drell-Yan model. Comparison of muon-pair production by ?+ and ?- beams shows the cross-section ratio follows Drell-Yan model expectations, except for a dip in ?(?+)/?(?-) near x/sub ?/ near 1. The same data are also used to extract the ratio of the sea to valence quark distributions in the nucleon, with improved accuracy for x/sub N/ 2 for the ?- data sample. This provides stronger evidence of a rise in the nucleon structure function for x/sub N/ < 0.06 compared to that extracted in deep-inelastic lepton scattering. The issue is raised of the nonuniqueness of the definition of x/sub ?/ and x/sub N/ used in the Drell-Yan analysis. A definition proposed by Soper has superior invariance properties to that commonly used. An analysis based on this definition yields generally similar results for the pion and nucleon structure function, compared to use of the common definition. However, the pion structure function shows a larger intercept at x/sub ?/ = 1 when the definition of Soper is used. 21 refs., 6 figs
Quark-parton structure functions of nuclei
International Nuclear Information System (INIS)
The previously available and new experimental data are used to discuss the properties of the structure functions of nuclei as independent (irreducible to one-nucleon) objects of hadron physics. The basic data have been obtained by the Stavinsky group in experiments on limiting fragmentation of more than 20 nuclei from 7Li to 238U. The discovered properties of the quark-parton structure functions give evidence for the existence in nuclei of multiquark configurations which essentially differ from those present in both free nucleons and two-, three- and more nucleon systems. Experiments on deep inelastic scattering of leptons on nuclei performed by the CERN-Dubna NA-4 Collaboration, the European Muon Collaboration and at SLAC confirm the conclusions about the structure functions of nuclei drawn from nuclear limiting fragmentation studies
The role of strangeness in the nucleon structure
International Nuclear Information System (INIS)
It is shown that by reformulating an SU(3) Skyrmion model as a random phase approximation (RPA) to an underlying fermion (quark) theory, one can calculate microscopic (quark) properties of the nucleon without explicit account of the quark-gluon degrees of freedom. In this paper, the strangeness content of the proton can be estimated with a Skyrmion model that describes well the hyperon spectroscopy
Polarized Structure Functions and Spin Physics
Stösslein, U
2002-01-01
Recent progress in the field of spin physics of high energy particle interactions is reviewed with particular emphasis on the spin structure functions as measured in polarized deep inelastic lepton-nucleon scattering (DIS). New measurements are presented to obtain more direct information on the composition of the nucleon angular momentum, with results from semi-inclusive DIS accessing flavour-separated parton distribution functions (PDF) and with first data from hard exclusive reactions which may be interpreted in terms of recently developed generalizations of parton distribution functions (GPD). Finally, experimental prospects are outlined which will lead to a further development of the virtues of QCD phenomenology of the spin structure of the nucleon.
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.
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.
Experimental Studies of Quark-Gluon Structure of Nucleons and Nuclei
International Nuclear Information System (INIS)
The NMSU group has a lengthy history in the study of the nucleon structure and in particular its spin structure in terms of its fundamental constituents. This line of research is continuing in our current involvement in experiments at Brookhaven National Lab and the Thomas Jefferson National Accelerator Facility
Impact of the recent Jefferson lab data on the structure of the nucleon
Scientific Electronic Library Online (English)
W.R.B. de, Araújo; T., Frederico; M., Beyer; H.J., Weber.
2004-03-01
Full Text Available The simultaneous fit of proton ratio m pG Ep/G Mp, qF2p/F1p to the recent experimental data and static properties of the nucleon is studied within a light-front model with different spin coupling schemes and wave functions. The position of the zero of proton electric form factor is sensitive to the [...] presence of a hard constituent quark component in the nucleon wave function. The fitting of the new data for the ratios is achieved with a hard momentum scale about 4-5 GeV.
International Nuclear Information System (INIS)
We performed a self-consistent calculation of the nuclear matter properties within the Green's function scheme. Essential is the self-energy ?(p;epsilon) (effective single-particle potential or mass operator), which determines the properties of the system. Necessary for the calculation of the effective single-particle potential is the knowledge of the scattering matrix (T-matrix) in matter, which plays in the calculation the role of an effective two-body potential. Our calculations were performed for the 'phenomenological' hardcore potential of Hamada-Johnston, the Reid-soft-core potential and the 'realistic' Paris-Nucleon-Nucleon potential. A binding energy of -5.88 MeV per nucleon was obtained. For the Reid-soft-core potential and the Paris potential we found -11 MeV and -12.2 MeV respectively. (orig./HSI)
Structure of the real part of the nucleon optical potential
International Nuclear Information System (INIS)
The components of the nucleon optical potential V(l, E) in the 208Pb and 40Ca nuclei are calculated on the basis of the generalized Hartree-Fock potential and using typical sets of vacuum NN forces. The parameters of the isoscalar component of V(1, E) are found to agree well with those of phenomenological optical potentials and of the optical potentials in the Skyrme model. The isovector component of V(1, E) strongly depends on energy, and its value at E = 0 is considerably less than the corresponding values of the phenomenological and Skyrme optical potentials. This points to the necessity of additional tests of the underlying pair NN potentials. The radial distribution of V(1, E) is more complicated than the radial dependence of phenomenological optical potentials. 6 refs., 5 figs
The polarized structure function with an effective potential
International Nuclear Information System (INIS)
We use a quark model, with an effective potential, to obtain the polarized structure function of the quarks in the nucleon. In the present approach, we consider the harmonic oscillator potential for the quarks. (author)
Evolution of the nucleon structure in light nuclei
International Nuclear Information System (INIS)
The evolution of the EMC effect as a function of atomic mass A is considered for the first time for the lightest nuclei, D, 3He and , 4He, with an approach based on the Bethe-Salpeter formalism. We show that the pattern of the oscillation of the ratio rA(x)=F2A/F2N(D) with respect to the line rA(x)=1 varies with A, unlike the pattern for nuclei with masses A>4, where only the amplitude of the oscillation changes. It is found that the shape of the structure function distortions, which is typical for metals, is being reached in 3He
International Nuclear Information System (INIS)
The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter PD ?1/4 (which specifies deformation) fits gA (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(?N?), the double delta coupling constant1 fsub(???), the Ml transition moment ??N and g1p the spin structure function of proton2. All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs
A pure $S$-wave covariant model for the nucleon
Energy Technology Data Exchange (ETDEWEB)
Franz Gross; G. Ramalho; M.T. Pena
2008-01-01
Using the manifestly covariant spectator theory, and modeling the nucleon as a system of three constituent quarks with their own electromagnetic structure, we show that all four nucleon electromagnetic form factors can be very well described by a manifestly covariant nucleon wave function with zero orbital angular momentum.
Pion nucleon vertex function and the one pion exchange potential
International Nuclear Information System (INIS)
The ?NN vertex function is calculated from field theory and dispersion relations. It contains no adjustable parameters, the only input being S- and P-wave for ???N anti-N. This vertex function, having an effective cut-off mass of 5? and a r.m.s. radius of 52fm, compares well with previous experimental determinations. The effects from the 3? dressing of the ? propagator are found to be negligible. The corrected OPEP is significantly different from the uncorrected one-pion exchange potentiel (OPEP) for r<1.5fm. The inclusion of the corrected OPEP in meson exchange potentials will improve agreement with phenomenology
Study of two-nucleon wave functions in 3He
International Nuclear Information System (INIS)
The 3He(p,2p)pn reaction has been studied in a quasi-free scattering arrangement characterized by (anti) p(recoil) = 0 and various excitation or total energies E(recoil) of the unobserved p-n pair. Data were obtained at 250 and 400 MeV at symmetric and asymmetric pairs of angles. The 3He spectral function deduced in the framework of the plane wave impulse approximation is compared to the predictions of Faddeev and variational calculations. Comparisons are also made with p-n relative motion momentum distributions as the overlap between plane waves for the p-n pair and Irving, Irving-Gunn and Khanna wave functions for 3He
Nucleon structure from Lattice QCD using a nearly physical pion mass
International Nuclear Information System (INIS)
We report the first Lattice QCD calculation using the almost physical pion mass m?=149 MeV that agrees with experiment for four fundamental isovector observables characterizing the gross structure of the nucleon: the Dirac and Pauli radii, the magnetic moment, and the quark momentum fraction. The key to this success is the combination of using a nearly physical pion mass and excluding the contributions of excited states. An analogous calculation of the nucleon axial charge governing beta decay has inconsistencies indicating a source of bias at low pion masses not present for the other observables and yields a result that disagrees with experiment
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.
Low energy structure of the nucleon from chiral effective field theory
Directory of Open Access Journals (Sweden)
Alarcón Jose Manuel
2014-01-01
Full Text Available We present some updated results regarding the scalar and electromagnetic structure of the nucleon obtained by the relativistic formulation of chiral effective field theory with baryons. We compare them with previous determinations available in the literature, and show their relevance for searches of physics beyond the standard model in the low energy frontier.
Challenges in the global QCD analysis of parton structure of nucleons
International Nuclear Information System (INIS)
We briefly summarize the current status of global QCD analysis of the parton structure of the nucleon and then highlight the open questions and challenges which confront this endeavor on which much of the phenomenology of the Standard Model and the search of New Physics depend
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
Kaiser, N.
2012-03-01
A recent calculation of the nuclear energy density functional from chiral two- and three-nucleon forces is extended to the isovector terms pertaining to different proton and neutron densities. An improved density-matrix expansion is adapted to the situation of small isospin asymmetries and used to calculate in the Hartree-Fock approximation the density-dependent strength functions associated with the isovector terms. The two-body interaction comprises of long-range multi-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition, the leading-order chiral three-nucleon interaction is employed with its parameters fixed in computations of nuclear few-body systems. With this input one finds for the asymmetry energy of nuclear matter the value A( ? 0) ? 26.5 MeV, compatible with existing semi-empirical determinations. The strength functions of the isovector surface and spin-orbit coupling terms come out much smaller than those of the analogous isoscalar coupling terms and in the relevant density range one finds agreement with phenomenological Skyrme forces. The specific isospin and density dependences arising from the chiral two- and three-nucleon interactions can be explored and tested in neutron-rich systems.
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
Energy Technology Data Exchange (ETDEWEB)
Kaiser, N. [Technische Universitaet Muenchen, Physik Department T39, Garching (Germany)
2012-03-15
A recent calculation of the nuclear energy density functional from chiral two- and three-nucleon forces is extended to the isovector terms pertaining to different proton and neutron densities. An improved density-matrix expansion is adapted to the situation of small isospin asymmetries and used to calculate in the Hartree-Fock approximation the density-dependent strength functions associated with the isovector terms. The two-body interaction comprises of long-range multi-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition, the leading-order chiral three-nucleon interaction is employed with its parameters fixed in computations of nuclear few-body systems. With this input one finds for the asymmetry energy of nuclear matter the value A({rho}{sub 0}) {approx_equal} 26.5 MeV, compatible with existing semi-empirical determinations. The strength functions of the isovector surface and spin-orbit coupling terms come out much smaller than those of the analogous isoscalar coupling terms and in the relevant density range one finds agreement with phenomenological Skyrme forces. The specific isospin and density dependences arising from the chiral two- and three-nucleon interactions can be explored and tested in neutron-rich systems. (orig.)
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 ...
International Nuclear Information System (INIS)
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in (arXiv:0910.4979) by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N2LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.
Energy Technology Data Exchange (ETDEWEB)
Gebremariam, B., E-mail: gebremar@gmail.co [National Superconducting Cyclotron Laboratory, 1 Cyclotron Laboratory, East-Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Bogner, S.K., E-mail: bogner@nscl.msu.ed [National Superconducting Cyclotron Laboratory, 1 Cyclotron Laboratory, East-Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Duguet, T., E-mail: thomas.duguet@cea.f [National Superconducting Cyclotron Laboratory, 1 Cyclotron Laboratory, East-Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); CEA, Centre de Saclay, IRFU/Service de Physique Nucleaire, F-91191 Gif-sur-Yvette (France)
2011-02-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in (arXiv:0910.4979) by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N{sup 2}LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.
A model study of nuclear structure functions
González Marhuenda, Pedro; Vento Torres, Vicente; Traini, Marco; Zambarda, Andrea
1994-01-01
We calculate the structure function for a deuteron using the hadronic quark cluster decomposition. By assuming that nuclei might be composed of quasi deuterons, we study their structure functions. The procedure enables a quantum mechanical parametrization of various scenarios, among them nuclear dynamics and nucleon swelling. Moreover it is specially suited to study quark exchange effects. We show, within a scheme where perturbative evolution effects are minimized, that the region around x=1 ...
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, É¡1p, in the deep inelastic (DIS regime are presented. They improve the statistical accuracy of the existing data and extend the kinematic domain to a lower value of x and higher values of Q2. A global NLO QCD fit of all É¡1 world data on the proton, deuteron and neutron has been achieved. The results give a quantification of the quark spin contribution to the nucleon spin, 0.26 < Î”Î£ < 0.34 at 3 (GeV/c2 in MÌ…SÌ… 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 É¡1 proton and deuteron measurements. Preliminary results of a reevaluation of the gluon polarization Î”É¡/É¡ 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 âŒ©Î”É¡/É¡âŒª = 0.113 Â± 0.038 Â± 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.
International Nuclear Information System (INIS)
Nucleon-trinucleon overlap functions in 4He have been parametrized as a sum of exponentials, and are fitted to the charge form factor of4He. We present results with and without taking account of meson-exchange corrections
Self-consistent Green's functions calculation of the nucleon mean-free path
International Nuclear Information System (INIS)
Transport coefficients provide a unique insight into the near-equilibrium behavior of quantum many-body systems. The mean-free path, ?, of a particle within a dense medium is a basic transport coefficient, at the basis of several theoretical concepts and closely related to experimentally measured quantities. Green's functions techniques are particularly well suited to study such transport properties, since they are naturally formulated in the time domain. We present a calculation of the mean-free path of a nucleon in symmetric nuclear matter using self-consistent ladder self-energies extended to the complex energy plane. Our results indicate that, for energies above 50 MeV at densities close to saturation, a nucleon has a mean-free path of 4 to 5 femtometers.
International Nuclear Information System (INIS)
When the new data on polarised lepton nucleon scattering are compared at the same value of Q2 and with a common set of assumptions, a consistent picture of the spin content of the nucleon begins to emerge. Higher order effects in 0(?s), higher twist effects, modern data on unpolarized structure functions and an updated value for F/D are all important in analysing the data. The detailed x dependences of the polarisation asymmetry in the valence quark region are shown to confirm 20 year old predictions of the quark model and I argue that these are an important ingredient in decoding the nucleon spin puzzle. (author)
International Nuclear Information System (INIS)
When the new data on polarised lepton nucleon scattering are compared at the same value of Q2 and with a common set of assumptions, a consistent picture of the spin content of the nucleon begins to emerge. Higher order effects in O(?s), higher twist effects, modern data on unpolarised structure functions and an updated value for F/D are all important in analysing the data. The detailed x dependences of the polarisation asymmetry in the valence quark region are shown to confirm 20 year old predictions of the quark model and I argue that these are an important ingredient in decoding the nucleon spin puzzle. (author)
Wave functions of the nucleon and its parity partner from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Warkentin, Nikolaus; Braun, Vladimir M.; Goeckeler, Meinulf [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)
2008-11-15
We compute moments of distribution amplitudes using gauge configurations with two flavors of clover fermions from QCDSF/DIK and operators which are optimized with respect to their behavior under the lattice symmetries. The knowledge of these quantities helps in understanding the internal structure of hadrons and in the analysis of (semi-)exclusive processes. We present results for the nucleon distribution amplitude which suggest that the asymmetries (the deviations from the asymptotic form) are smaller than indicated by sum rule calculations. Using the same approach we were also able to calculate the same quantities for the N{sup *}(1535), the parity partner of the nucleon. These results show a stronger deviation from the asymptotic form. (orig.)
?N, ?N interactions: structure functions, higher twist
International Nuclear Information System (INIS)
Data on deep inelastic scattering of leptons by nucleons and nuclei have been accumulated for several years. Results exist from several experiments with electron, muon, neutrino beams. In this talk I shall review the most recent experiments which measured nucleon structure functions with ? and ? beams. In particular, I will summarize the results on R = sigma/sub L//sigma/sub T/ measurement, on F2(x,Q2), and xF3(x,Q2), and their interpretation in terms of QCD, including both gluon radiation and higher twist phenomena
Electromagnetic structure of few-nucleon ground states
Marcucci, L. E.; Gross, F.; Peña, M. T.; Piarulli, M.; Schiavilla, R.; Sick, I.; Stadler, A.; Van Orden, J. W.; Viviani, M.
2016-02-01
Experimental form factors of the hydrogen and helium isotopes, extracted from an up-to-date global analysis of cross sections and polarization observables measured in elastic electron scattering from these systems, are compared to predictions obtained in three different theoretical approaches: the first is based on realistic interactions and currents, including relativistic corrections (labeled as the conventional approach); the second relies on a chiral effective field theory description of the strong and electromagnetic interactions in nuclei (labeled ?EFT) the third utilizes a fully relativistic treatment of nuclear dynamics as implemented in the covariant spectator theory (labeled CST). For momentum transfers below Q? 5 fm?1 there is satisfactory agreement between experimental data and theoretical results in all three approaches. However, at Q? 5 fm?1, particularly in the case of the deuteron, a relativistic treatment of the dynamics, as is done in the CST, is necessary. The experimental data on the deuteron A structure function extend to Q? 12 fm?1, and the close agreement between these data and the CST results suggests that, even in this extreme kinematical regime, the study of few-body form factors provides no evidence for new effects coming from quark and gluon degrees of freedom at short distances.
The Structure of the Nucleon and its Excited States
International Nuclear Information System (INIS)
The past year has been an exciting and productive one for particle physics research at Abilene Christian University. The thrust of our experimental investigations is the study of the nucleon and its excited states. Laboratories where these investigations are presently being conducted are the AGS at Brookhaven, Fermilab and LAMPF. Some analysis of the data for experiments at the Petersburg Nuclear Physics Institute (Gatchina, Russia) is still in progress. Scheduling of activities at different laboratories inevitably leads to occasional conflicts. This likelihood is increased by the present budget uncertainties at the laboratories that make long-term scheduling difficult. For the most part, the investigators have been able to avoid such conflicts. Only one experiment received beam time in 1994 (E890 at the AGS). The situation for 1995-1996 also appears manageable at this point. E890 and another AGS experiment (E909) will run through May, 1995. El 178 at LAMPF is presently scheduled for August/September 1995. E866 at Fermilab is scheduled to start in Spring/Summer 1996. Undergraduate student involvement has been a key element in this research contract since its inception. Summer students participated at all of the above laboratories in 1994 and the same is planned in 1995. A transition to greater involvement by graduate students will provide cohesiveness to ACU involvement at a given laboratory and full-time on-site involvement in the longer running experiments at FNAL and BNL. Funds to support a full-time graduate student are requested this year. Finally, collaboration by Russian, Croatian and Bosnian scientists has proven to be mutually beneficial to these experimental programs and to the overall programs at the institutions involved. Past support has been augmented by other grants from government agencies and from the Research Council at Abilene Christian University. Additional funds are requested in this renewal to enable more programmatic support for these efforts, so that long-range plans can be made to carry out the experiments and to perform the analysis
Gebremariam, B; Duguet, T
2010-01-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam {\\it et al.} to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N$^2$LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a cutoff-dependent coupling {\\it constant} arising from zero-range contact interactions and a cutoff-independent coupling {\\it function} of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions...
Lepton Scattering on Nuclei at $x$ > 1 and the Nucleon Spectral Function
De Córdoba, P F; Müther, H; Oset, E; Faessler, A
1998-01-01
We analyze the processes of deep inelastic and quasielastic scattering in the region of x > 1. These processes are found to be very sensitive to the information contained in the nucleon spectral function in nuclei, particularly to the correlations between energy and momentum. Calculations are done using two spectral functions for nuclear matter and one for finite nuclei, ^{16}O. Several approximations are also analyzed and are shown to be inaccurate in this region. These results stress the fact that the region of x > 1 contains important information on nuclear dynamical correlations.
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
Kaiser, N
2009-01-01
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from $1\\pi$-exchange, iterated $1\\pi$-exchange, and irreducible $2\\pi$-exchange with intermediate $\\Delta$-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass $M^*(\\rho)$ entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength $F_\
Lynn, J E
2015-01-01
I discuss our recent work on Green's function Monte Carlo (GFMC) calculations of light nuclei using local nucleon-nucleon interactions derived from chiral effective field theory (EFT) up to next-to-next-to-leading order (N$^2$LO). I present the natural extension of this work to include the consistent three-nucleon (3N) forces at the same order in the chiral expansion. I discuss our choice of observables to fit the two low-energy constants which enter in the 3N sector at N$^2$LO and present some results for light nuclei.
International Nuclear Information System (INIS)
Fundamental interactions of spinning electrons at an interelectron separation less than 578.8 fm yield attractive electromagnetic forces with S = 0 creating vibrations under a motional emf. They explain the indistinguishability of electrons and give a vibration energy able for calculating the ground-state energies of many-electron atoms without using any perturbative approximation. Such forces create two-electron orbitals able to account for the exclusion principal and the mechanism of covalent bonds. In the outer subshells of atoms the penetrating orbitals interact also as pair-pair systems and deform drastically the probability densities of the quantum mechanical electron clouds. Such a dynamics of deformation removes the degeneracy and leads to the deviation from the shell scheme. However in the interior of atoms the large nuclear charge leads to a spherically symmetric potential with non-interacting pairs for creating shells of degenerate states giving an accurate explanation of the X-ray lines. On the other hand, considerable charge distributions in nucleons as multiples of 2e/3 and - e/3 determined by the magnetic moments, interact for creating the nuclear structure with p-n bonds. Such spin-spin interactions show that the dominant concept of the untisymmetric wave function for fermions is inapplicable not only in the simple p-n, p-p, and n-n systems but also in the LS coupling of atoms in which the electrons interact from different quantum states giving either S = 0 or S = l. (author)
The scale dependence of single-nucleon shell structure
Somà, V.; Duguet, T.; Hergert, H.; Holt, J. D.
2015-10-01
We address the scale dependence of (effective) single-particle energies, non-observable quantities that are commonly used for interpreting nuclear structure observables measured in experiments and computed in many-body theories. We first demonstrate their scale dependence on a formal level, making them intrinsically theoretical objects, before illustrating this point via ab initio calculations in the oxygen isotopes. Finally, we consider a modified definition of effective single-particle energy and investigate its running properties.
Advances on statistical/thermodynamical models for unpolarized structure functions
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus do Mucuri, 39803-371, Teofilo Otoni, Minas Gerais (Brazil); Tomio, Lauro [Instituto de Fisica Teorica, Universidade Estadual Paulista, R. Dr. Bento Teobaldo Ferraz 271, Bl II Barra Funda, 01140070, Sao Paulo, SP (Brazil)
2013-03-25
During the eights and nineties many statistical/thermodynamical models were proposed to describe the nucleons' structure functions and distribution of the quarks in the hadrons. Most of these models describe the compound quarks and gluons inside the nucleon as a Fermi / Bose gas respectively, confined in a MIT bag with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries {sup -}d/{sup -}u and {sup -}d-{sup -}u.
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
Kaiser, N
2012-01-01
A recent calculation of the nuclear energy density functional from chiral two- and three-nucleon forces is extended to the isovector terms pertaining to different proton and neutron densities. An improved density-matrix expansion is adapted to the situation of small isospin-asymmetries and used to calculate in the Hartree-Fock approximation the density-dependent strength functions associated with the isovector terms. The two-body interaction comprises of long-range multi-pion exchange contributions and a set of contact terms contributing up to fourth power in momenta. In addition, the leading order chiral three-nucleon interaction is employed with its parameters fixed in computations of nuclear few-body systems. With this input one finds for the asymmetry energy of nuclear matter the value $A(\\rho_0) \\simeq 26.5\\,$MeV, compatible with existing semi-empirical determinations. The strength functions of the isovector surface and spin-orbit coupling terms come out much smaller than those of the analogous isoscalar...
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.
Review of nucleon-nucleon scattering experiments and many dinucleon resonances
International Nuclear Information System (INIS)
Structures appearing in various experimental data (particularly those with polarized beams) in nucleon-nucleon systems are reviewed. A number of candidates are presented for dibaryon resonances which can couple to nucleon-nucleon systems
What we can learn about nucleon spin structure from recent data
Goshtasbpour, M; Ramsey, Gordon P
1997-01-01
We have used recent polarized deep-inelastic scattering data from CERN and SLAC to extract information about nucleon spin structure. We find that the SMC proton data, the E142 neutron data and the deuteron data from SMC and E143 give different results for fractions of the spin carried by each of the constituents. These appear to lead to two different and incompatible models for the polarized strange sea. The polarized gluon distribution occuring in the gluon anomaly does not have to be large in order to be consistent with either set of experimental data. However, it appears that the discrepancies in the implications of these data cannot be resolved with any simple theoretical arguments. We conclude that more experiments must be performed in order to adequately determine the fraction of spin carried by each of the nucleon constituents.
What we can learn about nucleon spin structure from recent data
International Nuclear Information System (INIS)
We have used recent data from the CERN and SLAC to extract information about nucleon spin structure. We find that the SMC proton data on ?01g1pdx, the E142 neutron data on ?01g1ndx, and the deuteron data from the SMC and E143 give different results for fractions of the spin carried by each of the constituents. These appear to lead to two different and incompatible models for the polarized strange sea. The polarized gluon distribution occurring in the gluon anomaly does not have to be large in order to be consistent with either set of experimental data. However, it appears that the discrepancies in the implications of these data cannot be resolved with any simple theoretical arguments. We conclude that more experiments must be performed in order to adequately determine the fraction of spin carried by each of the nucleon constituents. copyright 1997 The American Physical Society
Nuclear Effects In The F_3 Structure Function For Finite And Asymptotic Q^2
Kulagin, S. A.
1998-01-01
We study nuclear effects in the structure function F_3 which describes the parity violating part of the charged-current neuitrino nucleon deep inelastic scattering. Starting from a covariant approach we derive a factorized expression for the nuclear structure function in terms of nuclear spectral function and off-shell nucleon structure functions valid for arbitrary momentum transfer Q and in the limit of weak nuclear binding, i.e. when a nucleus can be treated as a non-rela...
Meson-nucleon scattering in the functional quantum theory of the non linear spinor field
International Nuclear Information System (INIS)
The results of this work are sumarized in the following points: 1. Determination of coupling constants, based on the nucleon eigenvalue equation with the two-point function, regularized by two single poles with small masses, gives a result deviating only little from the values given the theory with dipolar regularisation. These masses are considered here only as a means for regularisation and are not connected with physical particles. 2. The meson masses calculated are satisfying, too. So the two-point function, modified owing to the scalar product, has been shown to give equally good results for the calculation of coupling constants and mass eigenvalues. 3. In forward direction the differential cross section for pion-proton-scattering qualitively shows the correct behaviour. Indeed for back scattering a singularity exists which is characteristic for a theory with particles of zero mass. Thus ist seems necessary to first adapt the Greens function and to leave the unsymmetrical treatment of F and G. (orig.)
The role of spectator diquarks in deep inelastic structure functions
International Nuclear Information System (INIS)
The significance of the spectral distribution of diquarks in the nucleon for the SU(6) symmetry breaking in deep inelastic structure functions is investigated in a field theoretical framework, which ensures correct kinematical and symmetry properties for the structure functions. (orig.)
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.
On the effect of nucleon mass-shift and nucleon correlations on the EMC effect
International Nuclear Information System (INIS)
The influence on the EMC effect of nucleon mass-shift and short-range correlations determining a high momentum part of the nucleon momentum distribution is studied. The dispersion relation technique is used, the nucleus being related as a system consisting of A nucleons. It is shown that the ratio of the structure functions F2A(x)/F2N(x) is very sensitive to the correlations in the region x?0.3. It is demonstrated that decrease of the effective nucleon mass by 65 MeV, compared to the free value, leads to a quite satisfactory description of the EMC effect
Nucleon Compton scattering in the Dyson-Schwinger approach
International Nuclear Information System (INIS)
Full text: Compton scattering on the nucleon provides a unique tool to probe the nonperturbative structure of the nucleon. It allows access to a range of observables that are subject to studies at major experimental facilities, including: the nucleon's generalized polarizabilities; two-photon contributions to form factors; nucleon structure functions and generalized parton distributions; and proton antiproton annihilation processes. A nonperturbative approach for investigating such phenomena is given by the combination of QCD's Dyson-Schwinger equations with covariant Bethe-Salpeter and Faddeev equations. The framework has been recently applied for describing nucleon and delta elastic and transition form factors, and its systematic extension to Compton scattering, pion electroproduction and nucleon-pion scattering has been outlined. I will discuss recent progress in this area and present rst results for the nucleon's Compton scattering amplitude. (author)
Exchange currents and the internal structure of the nucleon in quark models
International Nuclear Information System (INIS)
The influence of internal nucleon structure on meson exchange currents has been investigated, in the framework of the non-relativistic constituent quark model and the MIT bag model with massless quarks. In comparison with the conventional theory of exchange currents, different strengths are found for the model-dependent higher-order terms and no ambiguity between pseudoscalar and pseudovector pion couplings. Furthermore, the retardation and excitation effects in the many-body system have to be treated consistently, in order to preserve gauge invariance. In this way 'damping' factors are obtained which differ in structure from the phenomenological form factors. (author)
Azimuthal Asymmetries: Access to Novel Structure Functions
International Nuclear Information System (INIS)
One of the most interesting consequence of non-zero intrinsic transverse momentum of partons in the nucleon is the nontrivial azimuthal dependence of the cross section of hard scattering processes. Many of the observable asymmetries contain unknown functions which provide essential information on the quark and gluon structure. Several of them have been studied in the last few years; we discuss their qualitative and quantitative features in semi-inclusive DIS
Azimuthal Asymmetries: Access to Novel Structure Functions
Oganessyan, K. A.; Asilyan, L. S.; Sanctis, E.; Muccifora, V
2002-01-01
One of the most interesting consequence of non-zero intrinsic transverse momentum of partons in the nucleon is the nontrivial azimuthal dependence of the cross section of hard scattering processes. Many of the observable asymmetries contain unknown functions which provide essential information on the quark and gluon structure. Several of them have been studied in the last few years; we discuss their qualitative and quantitative features in semi-inclusive DIS.
Polarised structure functions from the SMC experiment
Energy Technology Data Exchange (ETDEWEB)
Lamanna, M. [Istituto Nazionale di Fisica Nucleare, Trieste (Italy). Lab. Area di Ricerca
1998-06-01
The spin muon collaboration (SMC, NA47) at CERN has measured polarised structure functions of the nucleon in the years 1991-1996. All the published data on g{sub 1}{sup p} and g{sub 1}{sup d} are discussed and the new preliminary results of g{sub 1}{sup p} are presented. The test of the Bjorken sum rule and the violation of the Ellis-Jaffe sum rules are also discussed. (orig.). 30 refs.
Electro-magnetic nucleon form factors and their spectral functions in soliton models
Holzwarth, G
1996-01-01
It is demonstrated that in simple soliton models essential features of the electro-magnetic nucleon form factors observed over three orders of magnitude in momentum transfer t are naturally reproduced. The analysis shows that three basic ingredients are required: an extended object, partial coupling to vector mesons, and relativistic recoil corrections. We use for the extended object the standard skyrmion, one vector meson propagator for both isospin channels, and the relativistic boost to the Breit frame. Continuation to timelike t leads to quite stable results for the spectral functions in the regime from the 2- or 3-pion threshold to about two rho masses. Especially the onset of the continuous part of the spectral functions at threshold can be reliably determined and there are strong analogies to the results imposed on dispersion theoretic approaches by the unitarity constraint.
Quark-diquark approximation of the three-quark structure of a nucleon and the NN phase shifts
International Nuclear Information System (INIS)
The quark-diquark approximations of the three-quark structure of a nucleon are considered in the framework of the quark confinement model (QCM) based on definite concepts of the hadronization and quark confinement. The static nucleon characteristics (magnetic moments, ratio GA/GV and strong meson-nucleon coupling constants) are calculated. The behaviour of the electromagnetic and strong nucleon form factors is obtained at the low energy (0?02=-q22, where q is a transfer momentum). The one-boson exchange potential is constructed and the NN-phase-shifts are computed. Our results are compared with experiment and the Bonn potential model. 45 refs.; 7 figs.; 3 tabs
Hyperfine structure of ground-state nucleons in chiral quark model
Jia, Duojie; Dang, Wen-Bo; Zhao, Xing-Wen
2015-10-01
Hyperfine structure of ground-state nucleons is studied by checking the isospin breaking effect due to the non-zero differences of mass and electromagnetic interaction between the up and down quarks. It is shown using chiral nonlinear quark model that the isospin breaking corrections to the baryon mass are of the order of one percent relatively to hadronic energies. The computed mass splittings due to the hyperfine strong and the electromagnetic corrections are in good agreement with the recent data of the baryon mass splitings.
Status of nucleon structure calculations with 2+1 flavors of domain wall fermions
Lin, Meifeng
2013-01-01
We report the status of our nucleon structure calculations with 2+1 flavors of domain wall fermions on the RBC-UKQCD $32^3\\times64$ gauge ensembles with the Iwasaki+DSDR action. These ensembles have a fixed lattice scale of 1/a = 1.37 GeV, and two pion masses of about 170 and 250 MeV. Preliminary results for the isovector electromagnectic form factors and their corresponding root-mean-squared (r.m.s.) radii will be presented.
Isospin dependence of nucleon Correlations in ground state nuclei
Charity, R J; Sobotka, L G; Waldecker, S J
2013-01-01
The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean-field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. S...
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.
Measurement of spin structure functions at SLAC: a status report on the E143 experiment
International Nuclear Information System (INIS)
A status report is given on a new experiment performed recently at SLAC on polarized deep inelastic electron scattering. The E143 experiment will provide a precise measurement of the nucleon spin structure functions, allowing further tests of QCD Sum Rules and of the quarks contribution to the spin of the nucleon. copyright 1995 American Institute of Physics
Maydanyuk, Sergei P.; Zhang, Peng-Ming; Zou, Li-Ping
2016-01-01
We analyze the nucleon structure of the ? -decaying nucleus to see if it 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 the distribution of nucleons in the ? -decaying nuclear system. We conclude the following. (1) After inclusion of the nucleon structure in the model the calculated bremsstrahlung spectrum is changed very slowly for a majority of the ? -decaying nuclei. However, we have observed that visible changes really exist for the 106Te nucleus (Q?=4.29 MeV, T1 /2=70 ?s) 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 in 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 nucleon structure: (a) direction to nuclei with smaller Z and (b) direction to nuclei with larger Q? values.
International Nuclear Information System (INIS)
The topic of lepton-nucleon inclusive scattering is reviewed. Some of the experiments providing data on these interactions are described first. Then the constituent model of the nucleon and the contribution of various types of experiments are discussed; data from the experiments are compared and some simple predictions of the quark model are covered. Next, some of the fundamental notions behind quantum chromodynamics (QCD) are presented. Subsequent sections examine detailed tests of QCD. These include the ratio of longitudinal to transverse photoabsorption cross sections, the proton form factor in elastic ep scattering, and the dependence of structure functions on Q2. In conclusion, all the tests of QCD are tabulated, and the results are evaluated. 32 references, 33 figures, 4 tables
Moments of Spin Structure Functions: Sum Rules and Polarizabilities
Chen, Jian-ping
2010-01-01
Nucleon structure study is one of the most important research areas in modern physics and has challenged us for decades. Spin has played an essential role and often brought surprises and puzzles to the investigation of the nucleon structure and the strong interaction. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture in the strong region of the interaction and of the transition region from the strong to the asymptotic-free region. Insight for some aspects of the theory for the strong interaction, Quantum Chromodynamics (QCD), is gained by exploring lower moments of spin structure functions and their corresponding sum rules. These moments are expressed in terms of an operator-product expansion using quark and gluon degrees of freedom at moderately large momentum transfers. The higher-twist contributions have been examined through the evolution of these moments as the momentum transfer varies...
pp Elastic Scattering at LHC in a Nucleon-Structure Model
Islam, M M; Luddy, R J
2007-01-01
We predict pp elastic differential cross sections at LHC at c.m. energy 14 TeV and momentum transfer range |t| = 0 - 10 GeV*2 in a nucleon-structure model. In this model, the nucleon has an outer cloud of quark-antiquark condensed ground state, an inner shell of topological baryonic charge (r ~ 0.44F) probed by the vector meson omega, and a central quark-bag (r ~ 0.2F) containing valence quarks. We also predict elastic differential cross section in the Coulomb-hadronic interference region. Large |t| elastic scattering in this model arises from valence quark-quark scattering, which is taken to be due to the hard-pomeron (BFKL pomeron with next to leading order corrections). We present results of taking into account multiple hard-pomeron exchanges, i.e. unitarity corrections. Finally, we compare our prediction of pp elastic differential cross section at LHC with the predictions of various other models. Precise measurement of pp elastic differential cross section at LHC by the TOTEM group in the |t| region 0 - 5...
Litvinova, Elena
2015-01-01
The relativistic particle-vibration coupling (RPVC) model is extended by the inclusion of spin- and isospin-flip excitation modes into the phonon space, introducing a new mechanism of dynamical interaction between nucleons with different isospin in the nuclear medium. Protons and neutrons exchange by collective modes which are formed by isovector $\\pi$ and $\\rho$-mesons, in turn, softened considerably because of coupling to nucleons of the medium. These modes are investigated within the proton-neutron relativistic random phase approximation (pn-RRPA) and relativistic proton-neutron time blocking approximation (pn-RTBA). The appearance of isospin-flip states with sizable transition probabilities at low energies points out that they are likely to couple to the single-particle degrees of freedom and, in addition to isoscalar low-lying phonons, to modify their spectroscopic characteristics. Such a coupling is quantified for the shell structure of $^{100,132}$Sn and found significant for the location of the domina...
Elastic electron-deuteron scattering with new nucleon-nucleon potentials and nucleon form factors
International Nuclear Information System (INIS)
We present elastic e-d scattering observables obtained from the recent N-N interaction models proposed by the Bonn and Nijmegen groups. In particular, we discuss the pertinent results for the electric and magnetic structure functions as well as the deuteron tensor polarization and charge form factor, especially with respect to their dependence on the choice of the nucleon form factors. We find that for these new N-N potentials only a particular model of nucleon form factors, different from the traditional ones, allows for a comprehensive reproduction of all elastic e-d data at low and moderate momentum transfers. (author)
New measurements of high-momentum nucleons and short-range structures in nuclei
Fomin, N; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Bukhari, M H S; Chudakov, E; Clasie, B; Connell, S H; Dalton, M M; Daniel, A; Day, D B; Dutta, D; Ent, R; Fassi, L El; Fenker, H; Filippone, B W; Garrow, K; Gaskell, D; Hill, C; Holt, R J; Horn, T; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, M; Lindgren, R; Lung, A F; Malace, S; Markowitz, P; McKee, P; Meekins, D G; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Seely, J; Segbefia, E; Slifer, K; Smith, G R; Solvignon, P; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Trojer, R; Tvaskis, V; Vulcan, W F; Wasko, C; Wesselmann, F R; Wood, S A; Wright, J; Zheng, X
2011-01-01
We present new, high-Q^2 measurements of inclusive electron scattering from high-momentum nucleons in nuclei. This yields an improved extraction of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data extend to the kinematic regime where three-nucleon correlations are expected to dominate and we observe significantly greater strength in this region than previous measurements.
Gauge invariance, Lorentz covariance and canonical quantization in nucleon structure studies
Wang, Fan; Sun, W M; Zhang, P M; Wong, C W
2014-01-01
There are different operators of quark and gluon momenta, orbital angular momenta, and gluon spin in the nucleon structure study. The precise meaning of these operators are studied based on gauge invariance, Lorentz covariance and canonical quantization rule. The advantage and disadvantage of different definitions are analyzed. A gauge invariant canonical decomposition of the total momentum and angular momentum into quark and gluon parts is suggested based on the decomposition of the gauge potential into gauge invariant (covariant) physical part and gauge dependent pure gauge part. Challenges to this proposal are answered. \\keywords{Physical and pure gauge potentials; Gauge invariant canonical quark and gluon momenta, orbital angular momenta and spins; Homogeneous and non-homogeneous Lorentz transformations; Gauge invariant decomposition and gauge invariant extension; Classical and quantum measurements.
Influence of a shift of the nucleon mass and of nucleon correlations on the EMC effect
International Nuclear Information System (INIS)
We study the influence of a shift of the nucleon mass, and of the short-range nucleon correlations which determine the hard part of the nucleon momentum distribution, on the EMC effect. We use the technique of dispersion integration, within the framework of which the nucleus is described as a system consisting of A nucleons. We demonstrate that the ratio of the structure functions F/sup A/2(x)F/sup N/2(x) is rather sensitive to the correlations in the region of xapprox. >0.3 and show that a decrease of the effective nucleon mass by ?65 MeV in comparison with the free value leads to a rather satisfactory description of the EMC effect
Sea and gluon spin structure function measurements at RHIC
Energy Technology Data Exchange (ETDEWEB)
Yokosawa, A.
1995-02-01
The first polarized collider where one collides 250-GeV/c beams of 70% polarized protons at high luminosity is under construction. This will allow a determination of the nucleon spin-dependent structure functions over a large range in x and a collection of sufficient W and Z events to investigate extremely interesting spin-related phenomena.
Close, Francis Edwin
1995-01-01
This talk summarises the discussions during the conference on the spin structure of the nucleon held at Erice; July 1995. The summary focuses on where we have come, where we are now, and the emerging questions that direct where we go next in the quest to understand the nucleon spin.
International Nuclear Information System (INIS)
The properties and formation are described of ?-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of ?-nucleon atoms is shown. The prospects of their use are indicated. (J.P.)
Energy Technology Data Exchange (ETDEWEB)
Azhgirey, L. S.; Afanasiev, S. V.; Borzounov, Yu. T.; Golovanov, L. B.; Zolin, L. S., E-mail: zolin@sunhe.jinr.ru; Ivanov, V. I.; Isupov, A. Yu., E-mail: isupov@moonhe.jinr.ru; Ladygin, V. P.; Litvinenko, A. G.; Malakhov, A. I.; Penev, V. N.; Peresedov, V. F.; Pilipenko, Yu. K.; Reznikov, S. G.; Rukoyatkin, P. A.; Khrenov, A. N. [Joint Institute for Nuclear Research (Russian Federation)
2011-10-15
Experimental results on the vector (A{sub y}) and tensor (A{sub yy}) analyzing powers in the fragmentation of 5- and 9-GeV/c polarized deuterons to high-momentum pions in the kinematical region corresponding to pion production on a strongly correlated nucleon pair (cumulative meson production) are presented. The angular and momentum dependences of A{sub yy} are not described by calculations performed in the impulse approximation by using standard deuteron wave functions. An explanation for our data should be sought on the basis of models that treat the deuteron at short distances (deuteron-core region) as a multiquark state-for example, a 6q cluster, whose high orbital angular momentum (D wave) leads to the observed strong dependence of the reaction tensor analyzing power A(d-vector, {pi})X on the pion transverse momentum.
Probing spin-1 diquarks in deep inelastic structure functions
International Nuclear Information System (INIS)
Within the scope of a new diquark model for deep inelastic structure functions presented by us recently we use the existing data on F1sup(ep)(x,Q2) to learn about the admixture of spin-1 diquarks in nucleons. It turns out that they are so rare, heavy and extended compared to spin-0 diquarks that they are presumably accidental and not dynamical. Their number and form factors can be understood qualitatively within this picture. Still, the spin-1 diquarks give interesting structures in data and, together with quarks and spin-0 diquarks, carry enough momentum to account for the full nucleon energy. A gluon component is hence not needed in the nucleon. (orig.)
International Nuclear Information System (INIS)
The longitudinal charge function in the quasi-elastic peak region is calculated, including effects of two-nucleon collisions. The coupled RPA equation for 2p2h states is solved, using a Thomas-Fermi type theory. To calculate the response function for RPA orders, the Gogny force (a density dependent finite range force) is used, both for the mean field and the residual ph interaction. To include the 2p2h states it was necessary to study the dynamic nuclear mass operator M in the 2p1h (2h1p) approximation. The Gogny force was used as interaction at the vertex of the mass operator. The density dependence of the Gogny force gives a pronounced surface peak in the imaginary part of M. The inclusion of the mass operator in the ph motion gives 2p2h states. Their influence considerably reduces the RPA order response and generally produces a better agreement between theory and experiment, although inexplicable exceptions remain. The investigation suggests that it is not necessary to modify the nuclear form factor
Ab initio Nuclear structure Theory with chiral two- plus three-nucleon interactions
International Nuclear Information System (INIS)
Low-energy nuclear theory has entered an era of ab initio nuclear structure and reaction calculations based on input from QCD. One of the most promising paths from QCD to nuclear observables employs Hamiltonians constructed within chiral effective field theory as consistent starting point for precise ab initio nuclear structure and reaction studies. However, the full inclusion of chiral two- plus three-nucleon (NN+3N) interactions in exact and approximate many-body calculations still poses a formidable challenge. We discuss recent developments towards this goal, ranging from consistent Similarity Renormalization Group evolutions of NN+3N Hamiltonians to large-scale ab initio calculations for ground states and spectra in the Importance-Truncated No-Core Shell Model with full 3N interactions. We highlight recent achievements and discuss open issues and future perspectives for nuclear structure theory with QCD-based interactions. Moreover, we discuss successful steps towards merging ab initio structure and reaction theory and show applications to low-energy reactions in the p-shell relevant for astrophysics.
Nucleon Electromagnetic Form Factors
International Nuclear Information System (INIS)
Although nucleons account for nearly all the visible mass in the universe, they have a complicated structure that is still incompletely understood. The first indication that nucleons have an internal structure, was the measurement of the proton magnetic moment by Frisch and Stern (1933) which revealed a large deviation from the value expected for a point-like Dirac particle. The investigation of the spatial structure of the nucleon, resulting in the first quantitative measurement of the proton charge radius, was initiated by the HEPL (Stanford) experiments in the 1950s, for which Hofstadter was awarded the 1961 Nobel prize. The first indication of a non-zero neutron charge distribution was obtained by scattering thermal neutrons off atomic electrons. The recent revival of its experimental study through the operational implementation of novel instrumentation has instigated a strong theoretical interest. Nucleon electro-magnetic form factors (EMFFs) are optimally studied through the exchange of a virtual photon, in elastic electron-nucleon scattering. The momentum transferred to the nucleon by the virtual photon can be selected to probe different scales of the nucleon, from integral properties such as the charge radius to scaling properties of its internal constituents. Polarization instrumentation, polarized beams and targets, and the measurement of the polarization of the recoiling nucleon have been essential in the accurate separation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor
International Nuclear Information System (INIS)
The x dependence of hadron structure functions is investigated. If quarks can exist in very low mass states (10 MeV for d and u quarks) the pion structure function is predicted to behave like (1-x) and not (1-x)2 in a x-region around 1. Relativistic and non-relativistic quark bound state pictures of hadrons are considered together with their relation with the Q2 evolution of structure functions. Good agreement with data is in general obtained
Phenomenological nucleon-nucleon potential
International Nuclear Information System (INIS)
The present situation of the nucleon-nucleon problems and the essential points concerning the one-boson-exchange model and the Paris potential are briefly reviewed. The extension of the nucleon-nucleon potential up to 2.5 GeV is discussed, and our recent phenomenological method for this extension is explained. Some of the successful results obtained by this phenomenological method are also shown. (author)
On the influence of nucleon correlations and nucleon mass-shift on the EMC effect
International Nuclear Information System (INIS)
We study the influence of the EMC effect of nucleon mass-shift and short-range correlations determining a high momentum part of the nucleon momentum distribution. The dispersion relation technique is used, the nucleus being treated as a system consisting of A nucleus. It is shown that the ratio of the structure functions F2A(x)/F2N(x) is very sensitive to the correlations in the region x > or approx. 0.3. It is also shown that decrease of the nucleon mass by ? 65 MeV, compared to the free value, leads to a quite satisfactory description of the EMC effect. (orig.)
Probing The Standard Model And Nucleon Structure Via Parity-violating Electron Scattering
Humensky, T B
2003-01-01
Parity-violating electron scattering has developed over the last 25 years into a tool to study both the structure of electroweak interactions and the structure of nucleons. This thesis reports work on two parity- violation experiments, the Hall A Proton Parity Experiment (HAPPEX) and SLAC E-158. HAPPEX (Jefferson Laboratory, 1998–1999) measured the parity-violating asymmetry in elastic e- p scattering at Q2 = 0.477 GeV2. This asymmetry is sensitive to the proton's strange elastic form factors. An asymmetry of ALR = ?15.05 ± 0.98(stat) ± 0.56(syst) ppm was measured. This asymmetry measurement allowed HAPPEX to set new constraints on the strange elastic form factors of the proton: GEs+0.392G Ms=0.025 ±0.20± 0.014, where GEs and GMs are the strange electric and magnetic form factors of the proton, respectively. The first error is the quadrature sum of the experimental errors and the second error is due to uncertainty in electromagnetic form fact...
Comments on pseudoscalar-nucleon coupling
International Nuclear Information System (INIS)
In the light of the recent EMC measurement of polarized muon-proton scattering we reexamine the coupling of the pseudoscalar Higgs boson to nucleons in a class of spontaneous CP-violation models where CP-violation can arise from the scalar-pseudoscalar Higgs boson mixings mechanism. Previous naive estimates of the effective direct Higgs-nucleon coupling can be reduced by taking into account the EMC data on the spin-dependent structure function. We show that this coupling can be consistent with being zero. This implies that the electric dipole moment of neutron induced by this Higgs-nucleon coupling in these models may vanish instead of dominating over the other contributions. Remarks on axion-nucleon coupling are also given
In-medium nucleon-nucleon potentials in configuration space
International Nuclear Information System (INIS)
Based on the thermodynamic Green function approach two-nucleon correlations in nuclear matter at finite temperatures are revisited. To this end, we derive phase-equivalent effective r-space potentials that include the effect of Pauli blocking at a given temperature and density. These potentials enter into a Schroedinger equation that is the r-space representation of the Galitskii-Feynman equation for two nucleons. We explore the analytical structure of the equation in the complex k-plane by means of Jost functions. We find that despite the Mott effect the correlation with deuteron quantum numbers are manifested as antibound states, i.e. as zeros of the Jost function on the negative imaginary axis of the complex momentum space. The analysis presented here is also suited for Coulombic systems. (author)
Electromagnetic Structure and Reactions of Few-Nucleon Systems in $\\chi$EFT
Schiavilla R.; Girlanda L.; Pastore S.; Viviani M.
2009-01-01
We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral effective field theory ($\\chi$EFT). The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and the...
The impact of a neutrino factory upon our knowledge of the internal structure of the nucleon
International Nuclear Information System (INIS)
A neutrino factory, used for short baseline physics, could provide unique and profound information about the internal structure of the nucleon. The unpolarized parton densities are already quite well known, thanks to a combination of neutral and charged current deep inelastic reactions over a wide range of Q2. But with high intensities available from a neutrino factory it would no longer be necessary to utilize heavy nuclear targets, leading to a vast improvement in the precision of the data. However, the impact on our knowledge of the polarized parton densities would be much more dramatic. There the quality of the data is excellent, but because of the impossibility of utilizing polarized targets with present day neutrino beams, charged current data does not exist and the neutral current data only provide information about the combinations [?q(x)+?q-bar(x)]. Thus nothing at all is known about the polarization of the valence quarks and the sea quarks separately! A truly dramatic improvement would follow from the construction of a neutrino factory. (author)
Neutron structure function from nuclear data
Energy Technology Data Exchange (ETDEWEB)
Melnitchouk, W. [Dept. of Physics, Univ. of Maryland, College Park, MD (United States); Thomas, A.W. [Dept. of Physics and Mathematical Physics, Univ. of Adelaide, Adelaide (Australia)
1996-06-01
The spin-averaged structure function of the neutron, F{sub 2}{sup n}, is extracted from the latest deuteron data, taking into account the most recent developments in the treatment of nuclear effects in the deuteron. At small x, the F{sub 2}{sup D}/F{sub 2}{sup p} ratio measured by the New Muon and Fermilab E665 Collaborations is interpreted to suggest a small amount of shadowing in deuterium, which acts to enhance F{sub 2}{sup n} for x {approx}< 0.1. A careful treatment of Fermi motion, binding and nucleon off shell effects in the deuteron also indicates that the neutron/proton structure function ratio as x {yields} 1 is consistent with the perturbative QCD expectation of 3/7, but larger than the traditional value of 1/4. (author) 40 refs, 5 figs
Deuteron Spin Structure Functions in the Resonance and DIS Regions
Energy Technology Data Exchange (ETDEWEB)
S. Kulagin; W. Melnitchouk
2007-10-03
We derive relations between spin-dependent nuclear and nucleon g_1 and g_2 structure functions, valid at all Q^2, and in both the resonance and deep inelastic regions. We apply the formalism to the specific case of the deuteron, which is often used as a source of neutron structure information, and compare the size of the nuclear corrections calculated using exact kinematics and using approximations applicable at large Q^2.
McGraw, John T. (Placitas, NM); Zimmer, Peter C. (Albuquerque, NM); Ackermann, Mark R. (Albuquerque, NM)
2012-01-24
Methods and apparatus for a structure function monitor provide for generation of parameters characterizing a refractive medium. In an embodiment, a structure function monitor acquires images of a pupil plane and an image plane and, from these images, retrieves the phase over an aperture, unwraps the retrieved phase, and analyzes the unwrapped retrieved phase. In an embodiment, analysis yields atmospheric parameters measured at spatial scales from zero to the diameter of a telescope used to collect light from a source.
Purely Functional Structured Programming
Obua, Steven
2010-01-01
The idea of functional programming has played a big role in shaping today's landscape of mainstream programming languages. Another concept that dominates the current programming style is Dijkstra's structured programming. Both concepts have been successfully married, for example in the programming language Scala. This paper proposes how the same can be achieved for structured programming and PURELY functional programming via the notion of LINEAR SCOPE. One advantage of this ...
Nucleon and pion structure with lattice QCD simulations at physical value of the pion mass
Abdel-Rehim, A; Constantinou, M; Dimopoulos, P; Frezzotti, R; Hadjiyiannakou, K; Jansen, K; Kallidonis, Ch; Kostrzewa, B; Koutsou, G; Mangin-Brinet, M; Oehm, M; Rossi, G C; Urbach, C; Wenger, U
2015-01-01
We present results on the nucleon scalar, axial and tensor charges as well as on the momentum fraction, and the helicity and transversity moments. The pion momentum fraction is also presented. The computation of these key observables is carried out using lattice QCD simulations at a physical value of the pion mass. The evaluation is based on gauge configurations generated with two degenerate sea quarks of twisted mass fermions with a clover term. We investigate excited states contributions with the nucleon quantum numbers by analyzing three sink-source time separations. We find that, for the scalar charge, excited states contribute significantly and to a less degree to the nucleon momentum fraction and helicity moment. Our analysis yields a value for the nucleon axial charge agrees with the experimental value and we predict a value of 1.027(62) in the $\\overline{\\text{MS}}$ scheme at 2 GeV for the isovector nucleon tensor charge directly at the physical point. The pion momentum fraction is found to be $\\langl...
Energy Technology Data Exchange (ETDEWEB)
D. Day
2007-03-01
The nucleon form factors are still the subject of active investigation even after an experimental effort spanning 50 years. This is because they are of critical importance to our understanding of the electromagnetic properties of nuclei and provide a unique testing ground for QCD motivated models of nucleon structure. Progress in polarized beams, polarized targets and recoil polarimetry have allowed an important and precise set of data to be collected over the last decade. I will review the experimental status of elastic electron scattering from the nucleon along with an outlook for future progress.
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.
Chiral perturbation theory with nucleons
Energy Technology Data Exchange (ETDEWEB)
Meissner, U.G.
1991-09-01
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, {pi}N scattering and the {sigma}-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.
Chiral perturbation theory with nucleons
International Nuclear Information System (INIS)
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, Ï€N scattering and the Ïƒ-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon
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
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.
Chiral three-nucleon interactions in ab-initio nuclear structure and reactions
International Nuclear Information System (INIS)
The prediction of nuclear structure and reaction observables based on nuclear Hamiltonians including two- and three-nucleon (NN+3N) interactions derived from chiral effective field theory constitutes a challenging task for ab-initio nuclear theory. In particular, the consistent inclusion of 3N interactions requires formal extensions of the many-body methods and, at the same time, causes a significant increase of the computational cost. This work presents the necessary steps for the inclusion and the subsequent application of 3N interactions in different ab-initio nuclear structure and reaction approaches. The first part is dedicated to the preparation of the chiral nuclear forces before they enter the many-body methods. It addresses the similarity renormalization group (SRG) as a tool to soften the initial chiral interactions and its generalization to consistently include 3N interactions. Moreover, the technically important 3N matrix-element management in a convenient basis for the subsequent many-body methods including an efficient storage scheme is discussed. In addition, a possibility to derive approximative schemes for 3N interactions using normal ordering is presented. In the second part the SRG-evolved chiral NN+3N Hamiltonians are applied in nuclear structure calculations using the importance truncated no-core shell model (IT-NCSM) as well as coupled-cluster theory. The impact of SRG-induced and chiral 3N interactions on ground-state energies and low-energy spectra of different p-shell nuclei is studied, including a sensitivity analysis concerning uncertainties of the chiral interactions in the 12C and 10B spectra. Furthermore, the first ab-initio study of even oxygen isotopes with explicit 3N interactions is presented, and by means of the normal-ordered two-body approximation the ground-state energy systematics of selected closed-shell nuclei throughout the calcium, nickel, and tin isotopic chains are obtained in qualitative agreement with experiment. The third part of this work focuses on 3N interactions in ab-initio nuclear scattering approaches. This includes a detailed discussion of the inclusion of 3N interactions in the no-core shell model combined with the resonating-group method (NCSM/RGM) with emphasis on the ability to treat targets beyond the lightest nuclei. The extended formalism is then applied to nucleon-4He scattering, where the 3N interaction overall improves scattering phase shifts, differential cross sections and analyzing powers. Finally, the no-core shell model with continuum approach, which constitutes a unified ab-initio approach to bound and scattering states resulting from the combination of the NCSM and the NCSM/RGM, is generalized to 3N interactions and applied to the neutron-8Be system to study the impact of the continuum on the 9Be energy levels. The results demonstrate the importance of the consistent treatment of continuum states.
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)
Colleen Ellis
2010-07-01
The G0 backward angle experiment, completed in Hall C of the Thomas Jefferson National Accelerator Facility (TJNAF), measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q2 = 0.22 and 0.63 (GeV/c)2. The asymmetries are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of lte 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. This was also the first measurement of the anapole moment effects in the axial-vector current at these four-momentum transfers.
Photon structure function revisited
Berger, Ch
2014-01-01
The flux of papers from electron positron colliders containing data on the photon structure function ended naturally around 2005. It is thus timely to review the theoretical basis and confront the predictions with a summary of the experimental results. The discussion will focus on the increase of the structure function with x (for x away from the boundaries) and its rise with log Q**2, both characteristics beeing dramatically different from hadronic structure functions. Comparing the data with a specific QCD prediction a new determination of the QCD coupling coupling constant is presented. The agreement of the experimental observations with the theoretical calculations of the real and virtual photon structure is a striking success of QCD.
QCD Sum Rules for Nucleon-Nucleon Interactions
Kondo, Y
1998-01-01
The QCD sum rules for spin-dependent nucleon-nucleon interactions are formulated and their physical implications are studied. The basic object of the study is the correlation function of the nucleon interpolating field, where the matrix element is taken with respect to the one-nucleon state. The dispersion integral of the correlation function around the nucleon threshold is investigated in detail. It turns out that the integral can be identified as a measure of the nucleon-nucleon interaction strength, which is proportional to the scattering length in the small scattering length limit and to one half of the effective range in the large scattering length limit. New operators must be taken into account in the OPE of the correlation function. There behavior operators do not vanish when the matrix element is taken with respect to the spin-nonaveraged one-nucleon state. The Wilson coefficients of such operators are calculated. The sum rules obtained in this manner relate the spin-dependent nucleon-nucleon interact...
Electromagnetic Structure and Reactions of Few-Nucleon Systems in Ï‡EFT
Directory of Open Access Journals (Sweden)
Schiavilla R.
2010-04-01
Full Text Available We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral eï¬€ective ï¬eld theory (Ï‡EFT. The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and thermal neutron captures on p, d, and 3He.
Renormalization of the nucleon currents in the nuclear medium and the nucleon-nucleon interaction
International Nuclear Information System (INIS)
The renormalization of the effective single nucleon current operators in the nuclear medium by two-nucleon exchange currents is reviewed. The exchange current operators fall into two classes: those which are implied by the nucleon-nucleon interaction, and those which are associated with transition couplings between different nonnucleonic configurations and thus model dependent. It is shown that the quenching of the axial current coupling constant and the electromagnetic isovector spin current density are mainly caused by the model dependent exchange current contributions and second order configuration mixing of the nucleon wave functions. The large enhancement of the axial charge coupling in the nuclear medium can on the other hand be ascribed to the combined effects of the well known pion exchange charge density operator and the model independent exchange current that is determined by the nucleon-nucleon interaction. ((orig.))
Lepton-nucleon scattering at high energies
International Nuclear Information System (INIS)
Recent theoretical developments in the field of inelastic lepton-nucleon scattering are reviewed with emphasis on physics at HERA. Structure functions at small Bjorken-x are discussed in detail. Further topics are photoproduction of jets, the gluon densities in proton and photon, charm physics, electroweak processes and the search for new particles and interactions. (orig.)
Nuclear Effects on the Extraction of Neutron Structure Functions
Schmidt, I; Schmidt, Ivan; Yang, Jian-Jun
2001-01-01
Nuclear effects in light nuclei due to the presence of spin-one isosinglet 6-quark clusters are investigated. The quark distributions of 6-quark clusters are obtained by using a perturbative QCD (pQCD) based framework, which allows us to get a good description of the ratio of the deuteron structure function to the free nucleon structure function. Nuclear effects on the extraction of the neutron structure functions $F_2^n$ and $g_1^n$ are estimated. We find that the effect on the extracted spin-dependent neutron structure function is very different from that on the spin-independent neutron structure function. The effect enhances the Bjorken sum by about 10%, whereas its correction to the Gottfried sum is rather small. The formalism for calculating nuclear effects is further used to evaluate the spin-dependent structure function of the $^3$He nucleus and a good self-consistent check is obtained.
Spin Structure Functions from Electron Scattering
International Nuclear Information System (INIS)
The spin structure of the nucleon can play a key testing ground for Quantum Chromo-Dynamics (QCD) at wide kinematic ranges from smaller to large four momentum transfer Q2. The pioneering experiments have confirmed several QCD sum rules at high Q2 where a perturbative picture holds. For a full understanding of QCD at various scales, various measurements were made at intermediate and small Q2 region and their interpretation would be a challenging task due to the non-perturbative nature. Jefferson Lab has been one of the major experimental facilities for the spin structure with its polarized electron beams and various polarized targets. A few QCD sum rules have been compared with the measured spin structure functions g1(x, Q2) and g2(x, Q2) at low Q2 and surprising results have been obtained for the spin polarizabilities, ?0 and (delta)LT . As for the proton spin structure functions, the lack of data for g2(x,Q2) structure functions has been complemented with a new experiment at Jefferson Lab, SANE. The results from SANE will provide a better picture of the proton spin structure at a wide kinematic range in x and Q2.
A-dependence of weak nuclear structure functions
International Nuclear Information System (INIS)
Effect of nuclear medium on the weak structure functions F2A(x,?Q2) and F3A(x,?Q2) 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, FiA/Fiproton and FiA/Fideuteron(i=2,3, A=12C, 16O, CH and H2O) are obtained
Transversity of quarks in a nucleon
Indian Academy of Sciences (India)
K Bora; D K Choudhury
2003-11-01
The transversity distribution of quarks in a nucleon is one of the three fundamental distributions, that characterize nucleon’s properties in hard scattering processes at leading twist (twist 2). It measures the distribution of quark transverse spin in a nucleon polarized transverse to its (in?nite) momentum. It is a chiral-odd twist-two distribution function – gluons do not couple to it. Quarks in a nucleon/hadron are relativistically bound and transversity is a measure of the relativistic nature of bound quarks in a nucleon. In this work, we review some important aspects of this less familiar distribution function which has not been measured experimentally so far.
Conflicting Coupling of Unpaired Nucleons and the Structure of Collective Bands in Odd-Odd Nuclei
International Nuclear Information System (INIS)
The conflicting coupling of unpaired nucleons in odd-odd nuclei is discussed. A very simple explanation is suggested for the damping of the energy spacing of the lowest levels in the rotational bands in odd-odd nuclei with the 'conflicting' coupling of an odd proton and an odd neutron comparative to those of the bands based on the state of a strongly coupled particle in the neighboring odd nucleus entering the 'conflicting' configuration.
Phenomenology of dark matter-nucleon effective interactions
Catena, Riccardo
2015-01-01
I compare the non-relativistic effective theory of one-body dark matter-nucleon interactions to current dark matter direct detection experiments and neutrino telescope observations, presenting exclusion limits on the coupling constants of the theory. In the analysis of direct detection experiments, I focus on the interference of different dark matter-nucleon interaction operators and on predictions observable at directional detectors. Interpreting neutrino telescope observations, I use new nuclear response functions recently derived through nuclear structure calculations and show that hydrogen is not the most important element in the exclusion limit calculation for the majority of the spin-dependent dark matter-nucleon interaction operators
Applications of Symmetry Breaking in Determining PDFs of the Nucleon
Cao, Fu-Guang
2011-01-01
Studying the possible breaking of various parton model symmetries by the parton distribution functions of the nucleon can provide important information for the non-perturbative structure of hadrons and the strong interaction. We review theoretical calculations for the breaking of flavor symmetry, quark-antiquark symmetry and charge symmetry in the unpolarized and polarized nucleons using the meson cloud model. We report an estimation for the total distribution of strange and antistrange quarks in the nucleon by combining theoretical calculations of SU(3) flavor symmetry breaking with light antiquark distributions obtained from global analysis of available experimental data.
Art and Structural Functionality
Franco GonzÃ¡lez, Fidel
2015-01-01
The learning in architecture has a complexity that is a field that must be synthetize aesthetics and functionality. Somehow students are not very effective when they try to mix this terms, in most of the physical topics. To reach this there is a subject â€œ Applied Physics to Structures â€œ that shows development of a unification process for learning, crucial to energetic parameters where Energy is the most fundamental parameter for all processes. After the theoretical explanati...
Nuclear energy density functional from chiral pion-nucleon dynamics: Isovector spin-orbit terms
International Nuclear Information System (INIS)
We extend a recent calculation of the nuclear energy density functional in the systematic framework of chiral perturbation theory by computing the isovector spin-orbit terms: (?-vector?p-?-vector?n)·(J-vectorp-J-vectorn)Gso(kf)+(J-vectorp-J-vectorn)2 GJ(kf). The calculation includes the one-pion exchange Fock diagram and the iterated one-pion exchange Hartree and Fock diagrams. From these few leading order contributions in the small momentum expansion one obtains already a good equation of state of isospin-symmetric nuclear matter. We find that the parameter-free results for the (density-dependent) strength functions Gso(kf) and GJ(kf) agree fairly well with that of phenomenological Skyrme forces for densities ?>?0/10. At very low densities, a strong variation of the strength functions Gso(kf) and GJ(kf) with density sets in. This has to do with chiral singularities m?-1 and the presence of two competing small mass scales kf and m?. The novel density dependencies of Gso(kf) and GJ(kf), as predicted by our parameter-free (leading order) calculation, should be examined in nuclear structure calculations
Charge structure of the hadronic final state in deep-inelastic muon-nucleon scattering
International Nuclear Information System (INIS)
The general charge properties of the hadronic final state produced in ?+p and ?+d interactions at 280 GeV are investigated. Quark charge retention and local charge compensation is observed. The ratio F2n/F2p of the neutron to proton structure function is derived from the measurement of the average hadronic charge in ?d interactions. (orig.)
The effect of confinement size on nuclear structure functions
International Nuclear Information System (INIS)
The differences in the structure function of a heavy nucleus, such as iron, compared to a light nucleus, are considered. In the context of QCD, a suggestion that these differences arise as a result of differences in the scale of confinement of the nuclear constituents is investigated. This results in a simple relationship between heavy and light nucleus structure functions which is in reasonable agreement with experiment if the confinement size in iron is around 10-20% greater than in a free nucleon. (author)
First moment of the flavour octet nucleon parton distribution function using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Constantinou, Martha; Hadjiyiannakou, Kyriakos; Koutsou, Giannis [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Dinter, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Institute for Advanced Study DIAS; Jansen, Karl [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Vaquero, Alejandro [INFN, Sezione di Milano-Bicocca, Milano (Italy); Collaboration: European Twisted Mass Collaboration
2015-03-15
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle {sup (8)}{sub ?{sup 2}=4} {sub GeV{sup 2}}. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed by S. Dinter et. al. (2012). We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)}) (with left angle x right angle {sup (3)} the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)})=0.39(1)(4).
Flavor asymmetry of the polarized nucleon sea
Nocera, Emanuele Roberto
2014-01-01
We discuss the flavor asymmetry of polarized light antiquarks in the nucleon, $\\Delta\\bar{u}-\\Delta\\bar{d}$. We present a determination of this quantity based on two global QCD analyses of experimental data, DSSV08 and NNPDFpol1.1, in which sea-quark parton distribution functions are determined respectively either from semi-inclusive deep-inelastic scattering or W-boson production data. The latter have become available only very recently, and their effect on the polarized flavor asymmetry is presented here for the first time. We find that the flavor asymmetry of polarized antiquarks in the nucleon is definitely positive, and has almost the same absolute size as its unpolarized counterpart. We compare this result with various theoretical models of the nucleon structure in order to test their validity. We show that some of them are clearly disfavored.
Alvioli, M; Kaptari, L P; Mezzetti, C B; Morita, H
2012-01-01
The nucleon momentum distribution n_A(k) for A=2, 3, 4, 16, and 40 nuclei is systematically analyzed in terms of wave functions resulting from advanced solutions of the non-relativistic Schr\\"{o}dinger equation, obtained within different many-body approaches and different realistic nucleon-nucleon (NN) interactions. In order to analyze and understand the frequently addressed question concerning the relationships between the nucleus, n_A(k), and the deuteron, n_D(k), momentum distributions, the spin(S)-isospin (T) structure of few-nucleon systems and complex nuclei is analyzed in terms of realistic NN interactions and many-body approaches. To this end the number of NN pairs in agiven (ST) state, viz. (ST)=(10), (00), (01), and (11), and the contribution of these states to the nucleon momentum distributions, are calculated. It is shown that, apart from the (00) state which has very small effects, all other spin-isospin states contribute to the momentum distribution in a wide range of momenta. It is shown that t...
Nucleon knockout: reaction mechanisms
International Nuclear Information System (INIS)
The treatment of the reactions mechanisms involved in nucleon knockout concerns the ideas of what actually happens in nucleon knockout, whether the deviations from the simplest plane wave picture interfere with an extraction of the wave function, and whether or not the desire to measure the bound state wave functions blinds one to the possibility of obtaining other interesting information from this reaction or from finding exciting new processes taking place. Included are the plane- and distorted-wave impulse approximations, some failures, and more sophisticated reaction mechanisms. 12C(P,2P) and 4He(P,2P) are discussed covering cross sections and spectroscopic factors
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.
International Nuclear Information System (INIS)
On the basis of the effective hamiltonians of (S, P, T, V, A) interactions of charged and neutral currents calculated are the differential cross sections of neutrino (antineutrino)-quark interactions with and without provision for the masses of the initial and final quarks, as well as the lepton helicity. The cross sections of deep inelastic neutrino (antineutrino)-nucleon scattering are obtained. Given are estimations of the phenomenological coupling constants of weak currents according to the available experimental data using the quark distributions accounting for deviation from scaling in deep inelastic electric production in the framework of asymptotically free gauging theories
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 Mayerâ€“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 Bohrâ€“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.
Axial structure of the nucleon in a three-flavor chiral quark-meson model
International Nuclear Information System (INIS)
Nucleon matrix elements of the 0, 3 and 8 flavor components of the axial current are calculated in an SU(3)L x SU(3)R chiral quark-meson model. An extension of the Gell-Mann-Levy lagrangian with effects of meson mixing is used. The cranking projection method is applied. The results are consistent with the recent EMC experiment, reinterpreted by taking into account non-perturbative effects. In particular, I find a sizable value of the flavor singlet axial current matrix element and a negligible contribution of the ss-bar components. 36 refs., 3 figs., 3 tabs. (author)
DEFF Research Database (Denmark)
Sinden, Richard R.; E. Pearson, Christopher; N. Potaman, Vladimir; Ussery, David
This chapter discusses the structure and function of DNA. DNA occupies a critical role in cells, because it is the source of all intrinsic genetic information. Chemically, DNA is a very stable molecule, a characteristic important for a macromolecule that may have to persist in an intact form for a...... long period of time before its information is accessed by the cell. Although DNA plays a critical role as an informational storage molecule, it is by no means as unexciting as a computer tape or disk drive. The structure of the DNA described by Watson and Crick in 1953 is a right handed helix of two...... individual antiparallel DNA strands. Hydrogen bonds provide specificity that allows pairing between the complementary bases (A.T and G.C) in opposite strands. Base stacking occurs near the center of the DNA helix and provides a great deal of stability to the helix (in addition to hydrogen bonding). The sugar...
DEFF Research Database (Denmark)
Sinden, Richard R.; E. Pearson, Christopher; N. Potaman, Vladimir; Ussery, David
1998-01-01
This chapter discusses the structure and function of DNA. DNA occupies a critical role in cells, because it is the source of all intrinsic genetic information. Chemically, DNA is a very stable molecule, a characteristic important for a macromolecule that may have to persist in an intact form for a long period of time before its information is accessed by the cell. Although DNA plays a critical role as an informational storage molecule, it is by no means as unexciting as a computer tape or disk d...
pp Elastic Scattering in Near Forward Direction at LHC and Nucleon Structure
Islam, M M; Prokudin, A V
2005-01-01
We predict pp elastic differential cross section at LHC at the c.m. energy 14 TeV and momentum transfer range |t| = 0-10 GeV*2, which is planned to be measured by the TOTEM group. The field theory model underlying our phenomenological investigation describes the nucleon as a composite object with an outer cloud of quark-antiquark condensate, an inner core of topological baryonic charge, and a still smaller quark-bag of valence quarks. The model satisfactorily describes the asymptotic behavior of sigma-total(s) and rho(s) as well as the measured antiproton-proton elastic differential cross section at c.m. energies 546 GeV, 630 GeV, and 1.8 TeV. The large |t| elastic amplitude of the model incorporates the QCD hard pomeron (BFKL Pomeron plus next to leading order approximations), the perturbative dimensional counting behavior, and the confinement of valence quarks in a small region within the nucleon. Our predicted pp elastic differential cross section at LHC is compared with those of Bourrely et al. and Desgro...
Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr
2015-05-29
We provide a unified ab initio description of the ^{6}Li ground state and elastic scattering of deuterium (d) on ^{4}He (?) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of ^{6}Li. The calculation reproduces the empirical binding energy of ^{6}Li, yielding an asymptotic D- to S-state ratio of the ^{6}Li wave function in the d+? configuration of -0.027, in agreement with a determination from ^{6}Li-^{4}He elastic scattering, but overestimates the excitation energy of the 3^{+} state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the ^{2}H(?,?)^{6}Li radiative capture, responsible for the big-bang nucleosynthesis of ^{6}Li. PMID:26066431
Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr
2015-05-01
We provide a unified ab initio description of the Li 6 ground state and elastic scattering of deuterium (d ) on He 4 (? ) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of Li 6 . The calculation reproduces the empirical binding energy of Li 6 , yielding an asymptotic D - to S -state ratio of the Li 6 wave function in the d +? configuration of -0.027 , in agreement with a determination from Li 6 -He 4 elastic scattering, but overestimates the excitation energy of the 3+ state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the H 2 (? ,? )Li 6 radiative capture, responsible for the big-bang nucleosynthesis of Li 6 .
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
Spin structure functions: a window into the structure of hadrons
International Nuclear Information System (INIS)
A large program of spin structure measurements is underway in Jefferson Lab's Hall B. Of particular interest is the first moment of the spin structure function g1, which goes through a rapid transition from the photon point (Q2 = 0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. One can then study the transition from hadronic to quark degrees of freedom over the whole range of Q2. It is also interesting to look for the onset of quark-hadron duality in spin structure functions. We use longitudinally polarized electrons with energies from 1.6 to 5.7 GeV incident upon polarized NH3 and ND3 targets to investigate proton and deuteron spin observables in and above the resonance region. We present the GDH and Bjorken integrals using the 1.6 and 5.7 GeV data and comment on the validity of local quark-hadron duality over the wide kinematical range (0.05 ? Q2 ? 4.5 GeV2 and W < 3.2 GeV) covered by this experiment
International Nuclear Information System (INIS)
The spin structure function g1(x, Q2) and the related longitudinally polarized parton densities ?f-(-)(x,Q2) are discussed in LO and NLO QCD for different factorization schemes within the common 'standard' scenario of polarized parton distributing functions (pdfs) with a flavour-symmetric light sea (antiquark) distribution ?q-bar and a completely SU(3)f broken 'valence' scenario with totally flavour-asymmetric light sea densities (?u-bar??d-bar??s-bar). The latter flavour-broken light sea densities are modelled with the help of a Pauli-blocking ansatz which complies with predictions of the chiral quark-soliton model and expectations based on the statistical parton model as well as with the corresponding, well established, flavour-broken unpolarized sea (d-bar>u-bar). Various parametrizations of polarized pdfs and results of recent analyses are discussed and compared, with particular emphasis on their implications at small x and for the polarized gluon distributions ?g(x, Q2). Further (future) direct measurements of ?u-bar and ?d-bar are discussed and suggested, such as polarized semi-inclusive DIS production processes of charged hadrons, polarized Drell-Yan (?*) dilepton production processes for future longitudinally polarized p-vector p-vector and p-vector d-vector collision experiments, and the production of weak vector bosons (W±, Z0) via singly and doubly longitudinally polarized pp and pn collisions. (author)
Leading nucleon production at HERA and the structure of the pion
International Nuclear Information System (INIS)
Experimental results from HERA on the production of leading neutrons in neutral current e+p collisions are reviewed. The data cover a large kinematic range from photoproduction to deep inelastic scattering. The neutrons are produced with low transverse momentum (pTL>0.2). Neutron production is studied relative to the inclusive cross section, reducing considerably the systematic error. The rate of neutrons in photoproduction is about half that expected from hadroproduction experiments. The photoproduction and hadroproduction data are otherwise in agreement and broadly in accord with particle-exchange models. There is a 20-30% rise in the rate of neutrons between photoproduction and deep inelastic scattering attributable to absorptive rescattering in the ?*p system. Aside from absorptive effects, the rate of neutron production depends only logarithmically on Q2, the virtuality of the exchanged photon, and x, the momentum fraction of the incoming proton carried by the struck quark. Factorization breaking is observed: for 0.64LL there is a weak dependence. Over the whole kinematic range from photoproduction to deep inelastic scattering, the structure function for leading neutron production is approximately given by F2LN(3)(x, Q2, xL), = A(Q2)F2(x, Q2)f(xL), where F2 is the structure function of the proton, f(xL) is the flux of neutrons and A(Q2) is an absorptive factor. The total ? ? cross section in photoproduction, ?(? ?), and the structure function of pion in deep inelastic scattering, F2?, can be extracted from the data on the assumption that pion exchange is the dominant mechanism for the production of leading neutrons. An effective flux method is introduced which avoids many theoretical uncertainties. ?(? ?) is found to be approximately one third ?(? p), violating quark counting rules which predict two thirds. The x and Q2 dependence of F2? is similar to F2. (author)
Relativistic effect on low-energy nucleon-deuteron scattering
Adhikari, S K; Adhikari, Sadhan K; Tomio, Lauro
1995-01-01
The relativistic effect on differential cross sections, nucleon-to-nucleon and nucleon-to-deuteron polarization transfer coefficients, and the spin correlation function, of nucleon-deuteron elastic scattering is investigated employing several three-dimensional relativistic three-body equations and several nucleon-nucleon potentials. The polarization transfer coefficients are found to be sensitive to the details of the nucleon-nucleon potentials and the relativistic dynamics employed, and prefer trinucleon models with the correct triton binding energy. (To appear in Phys. Rev. C)
Nuclear effects in the F3 structure function
Marco, E; Singh, S K
1998-01-01
By using a relativistic framework and accurate nuclear spectral functions we evaluate the ratio F_{3A}/AF_{3N} of deep inelastic neutrino scattering. Parametrizations of this ratio for different values of Q^2 are provided. These results should be useful for taking into account the nuclear effects in analyses of experimental data in neutrino reactions in nuclear targets, and test QCD predictions for the nucleon structure functions. In particular, the size of the nuclear corrections is of the same order of magnitude as the size of the QCD corrections to the Gross-Llewellyn Smith sum rule.
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...
Directory of Open Access Journals (Sweden)
F Zolfagharpour
2012-03-01
Full Text Available In this paper, we calculate nuclear structure function and EMC effect of 40Ca and 56Fe nuclei. To achive the goals, we consider Fermi motion and binding energy contrbiution in the harmonic oscillator model. In this model, harmonic oscillator parameter ?? related to shells root mean square radius and for free nucleon structure functions, is obtained from GRV’s free nucleon structure functions. Then, we calculate differential cross section of lepton scattering from those nuclei at the E=4.8 GeV and E=4.032 GeV. The obtained results show good agreement with available experimental data.
International Nuclear Information System (INIS)
Multiplicities for the semi-inclusive production of each charge state of ?± and K± mesons in deep-inelastic scattering are presented as a function of the kinematic quantities x, Q2, z and Phperpendicularto. The multiplicities were extracted from data collected by the HERMES experiment at the HERA storage ring using 27.6 GeV electron and positron beams on a hydrogen or deuterium gas target. These results for identified hadrons constitute the most precise measurement to date, and will significantly enhance our understanding of the proton structure, as well as the fragmentation process in deep-inelastic scattering. Furthermore, the 3D binning at an unprecedented level of precision provides a handle to help disentangle the transverse momentum structure of both. The high level of precision coupled with an intermediate energy regime requires a careful study of the complex interaction between the experimental systematics, theoretical uncertainties, and the applicability of the factorization theorem within the standard framework of leading-twist collinear QCD. This is illustrated by the extraction of the valence quark ratio d?/u? at leading-order in ?s. These results show a strong z-dependence below z ? 0.30, which could be interpreted as evidence for factorization breaking. This evidence weakens somewhat when isospin invariance of the fragmentation functions is assumed to be broken. Additionally, the multiplicities for the semi-inclusive production of ?0 mesons in deep-inelastic scattering are presented as a function of z. These multiplicities were extracted from the same data sample as used for the charged meson results. The neutral pion multiplicity is the same as the average charged pion multiplicity, up to z ? 0.70. This is consistent with isospin invariance below z ? 0.70. The results at high values of z show strong signs of isospin symmetry breaking.
International Nuclear Information System (INIS)
Enormous technical and economic benefits have been conferred on the industry in many countries by the application of nucleonic gauging. The last few years have witnessed many important advances in the field. Basically radioisotope instruments are used to measure a variety of physical properties of material in solid, liquid and gaseous state and many of them are designed to work in the industrial plants and fields under rigorous conditions
International Nuclear Information System (INIS)
Models for the pre-equilibrium emission of fast light particles are given based on exciton model. For the light ion reaction, energy spectra of p, d, 3He and alpha emission are given together with the calculation of the angular distribution of nucleon and alpha. A new model for the fast particle emission in heavy-ion reaction is introduced and applied to data analysis. (Auth.)
International Nuclear Information System (INIS)
Excitation functions of activation cross section (cascades over continuum states included) for proton capture in heavy nuclei, namely 52130Te(p, ?)53131I, 58142Ce(p, ?)59143Pr, 70176Yb(p, ?)71177Lu, 83209Bi(p, ?)84210Po, and integrated cross sections (direct transitions to the bound states) for neutron capture in 3989Y(n, ?)3990Y, 58140Ce(n, ?)58141Ce, 82208Pb(n, ?)82209Pb, were calculated within a preequilibrium-equilibrium exciton model, using the ground-state binding energy of the even nucleon reduced for pairing, as well as within the direct-semidirect capture model. The integrated cross sections calculated within both the approaches agree reasonably well with the available experimental data, though the models differ in many aspects. As the direct-semidirect model does not treat the transitions to the continuum states, only the preequilibrium-equilibrium model is applied to the activation data. It reproduces them rather successfully. (author)
Nucleon spin structure and pQCD frontier on the move
Pasechnik, Roman S; Teryaev, Oleg V; Solovtsova, Olga P; Khandramai, Vyacheslav L
2009-01-01
We discuss the interplay between higher orders of the perturbative QCD expansion and higher twist contributions in the analysis of recent Jefferson Lab (JLab) data on the lowest moments of spin-dependent proton and neutron structure functions $\\Gamma_1^{p,n} (Q^2)$ and Bjorken sum rule function $\\Gamma_1^{p-n}(Q^2)$ at $0.05
Energy Technology Data Exchange (ETDEWEB)
Jossten, Sylvester Johannes
2013-10-15
Multiplicities for the semi-inclusive production of each charge state of {pi}{sup {+-}} and K{sup {+-}} mesons in deep-inelastic scattering are presented as a function of the kinematic quantities x, Q{sup 2}, z and P{sub h} {sub perpendicular} {sub to}. The multiplicities were extracted from data collected by the HERMES experiment at the HERA storage ring using 27.6 GeV electron and positron beams on a hydrogen or deuterium gas target. These results for identified hadrons constitute the most precise measurement to date, and will significantly enhance our understanding of the proton structure, as well as the fragmentation process in deep-inelastic scattering. Furthermore, the 3D binning at an unprecedented level of precision provides a handle to help disentangle the transverse momentum structure of both. The high level of precision coupled with an intermediate energy regime requires a careful study of the complex interaction between the experimental systematics, theoretical uncertainties, and the applicability of the factorization theorem within the standard framework of leading-twist collinear QCD. This is illustrated by the extraction of the valence quark ratio d{sub {nu}}/u{sub {nu}} at leading-order in {alpha}{sub s}. These results show a strong z-dependence below z {approx} 0.30, which could be interpreted as evidence for factorization breaking. This evidence weakens somewhat when isospin invariance of the fragmentation functions is assumed to be broken. Additionally, the multiplicities for the semi-inclusive production of {pi}{sup 0} mesons in deep-inelastic scattering are presented as a function of z. These multiplicities were extracted from the same data sample as used for the charged meson results. The neutral pion multiplicity is the same as the average charged pion multiplicity, up to z {approx} 0.70. This is consistent with isospin invariance below z {approx} 0.70. The results at high values of z show strong signs of isospin symmetry breaking.
Sum rule measurements of the spin-dependent compton amplitude (nucleon spin structure at Q2 = 0)
International Nuclear Information System (INIS)
Energy weighted integrals of the difference in helicity-dependent photo-production cross sections (?1/2 - ?3/2) provide information on the nucleon's Spin-dependent Polarizability (?), and on the spin-dependent part of the asymptotic forward Compton amplitude through the Drell-Hearn-Gerasimov (DHG) sum rule. (The latter forms the Q2=0 limit of recent spin-asymmetry experiments in deep-inelastic lepton-scattering.) There are no direct measurements of ?1/2 or ?3/2, for either the proton or the neutron. Estimates from current ?-photo-production multipole analyses, particularly for the proton-neutron difference, are in good agreement with relativistic-l-loop Chiral calculations (?PT) for ? but predict large deviations from the DHG sum rule. Either (a) both the 2-loop corrections to the Spin-Polarizability are large and the existing multipoles are wrong, or (b) modifications to the Drell-Hearn-Gerasimov sum rule are required to fully describe the isospin structure of the nucleon. The helicity-dependent photo-reaction amplitudes, for both the proton and the neutron, will be measured at LEGS from pion-threshold to 470 MeV. In these double-polarization experiments, circularly polarized photons from LEGS will be used with SPHICE, a new frozen-spin target consisting of rvec H · rvec D in the solid phase. Reaction channels will be identified in SASY, a large detector array covering about 80% of 4?. A high degree of symmetry in both target and detector will be used to minimize systematic uncertainties
The EMC effect and the swelling of nucleons in nuclei
International Nuclear Information System (INIS)
The idea that nucleons could swell in the nuclear medium is issued from the EMC (European Muon Collaboration) effect, the observation that the deep inelastic structure functions in the scaling region differ from the bound nucleon and the free one. The structure function f2(x) for a free nucleon is shown. In this study, x is the Bjorken scaling variable x = Q2/2pq = Q2/2M? where (? q, ?) is the photon four-momentum and p that of the nucleon, and Q2 = q2 - ?2. Grouping all the experimental information the EMC effect divides in four regions, as shown in this paper. Very accurate data are now available from the NMC collaboration (New Muon Collaboration). They show that at very small x the ratio r between the structure function of a bound nucleon and that of a free one, r = F2A(x)/F2N(x), is smaller than unity, owing to the hadronization of the photon, the so-called shadow region. The small-x enhancement, first displayed by EMC and later questioned, is now confirmed, with a more moderate enhancement. This is the so-called antishadow region
Comba, Peter
2010-01-01
Describes how the understanding of structure - property relationships may be used to interpret known compounds and how to design novel molecules and materials with the desired properties. This book covers the theoretical background, experimental techniques and applications of structure-property correlations
Quasi-elastic electron scattering and nucleon-nucleon correlations
International Nuclear Information System (INIS)
In this contribution we briefly review some recent results, illustrating the possibilities of obtaining information on short-range corelations (SRC) by the quasi-elastic (QE) electron scattering, where the reaction mechanism is expected to be governed mainly by one-body electromagnetic nucleon currents and multi-nucleon final states can be excited. The paper is organized as follows: In Sec. 2 the results of recent experiments on inclusive 4He(e,e') and exclusive 4He(e,e'p)3H reactions performed at Saclay with the aim of checking the one-body nature of the reaction mechanism, are presented; in Sec. 3, the y-scaling analysis of SLAC inclusive cross sections for complex nuclei and the extraction of the nucleon momentum distribution will be illustrated; in Sec. 4 the effects of SRC on the QE response function is analyzed in terms of different models of the nucleon Spectral Function. (orig.)
Nucleon-nucleon interaction of a chiral ?-? model at finite temperature
International Nuclear Information System (INIS)
By using the imaginery time Green's function method, the nucleon-nucleon interaction of the chiral ?-? model has been investigated under the one-loop approximation. The effective masses of the pion, ?-meson and ?-meson at finite temperature are given. We have found that the potential well of the nucleon-nucleon interaction becomes shallow as the temperature increases. At a critical temperature Tc (70 MEV) the potential well disappears. (author)
Dressing the cloudy bag model: Second-order nucleon-nucleon potential
International Nuclear Information System (INIS)
We calculate the second-order static physical nucleon-nucleon potential resulting from applying a unitary dressing transformation to the trilinear pion-nucleon interaction with cloudy bag model vertex functions. We find that for two physical nucleons separated by any distance greater than twice the bag radius this potential is exactly the usual one-pion exchange potential modified in strength by a factor 1.05 for a bag of radius 0.7 fm
Dressing the cloudy bag model: Second-order nucleon-nucleon potential
Energy Technology Data Exchange (ETDEWEB)
Hearn, D.J.; McMillan, M.; Raskin, A.
1983-12-01
We calculate the second-order static physical nucleon-nucleon potential resulting from applying a unitary dressing transformation to the trilinear pion-nucleon interaction with cloudy bag model vertex functions. We find that for two physical nucleons separated by any distance greater than twice the bag radius this potential is exactly the usual one-pion exchange potential modified in strength by a factor 1.05 for a bag of radius 0.7 fm.
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
Nucleon-nucleon interaction in constituent quark models
International Nuclear Information System (INIS)
By using the chiral quark model and the quark delocalization colour screening model, the phase shifts of nucleon-nucleon scattering for high partial waves are studied. The results of both the models are almost equivalent. None of the quark models used have found any resonance-like structure in 3F2, 3F3, 3F4 and 3H4 partial waves. (authors)
The EMC Effect and High Momentum Nucleons in Nuclei
Hen, O; Miller, G A; Piasetzky, E; Weinstein, L B
2013-01-01
Recent developments in understanding the influence of the nucleus on deep-inelastic structure functions, the EMC effect, are reviewed. A new data base which expresses ratios of structure functions in terms of the Bjorken variable $x_A=AQ^2/(2M_A q_0)$ is presented. Information about two-nucleon short-range correlations from experiments is also discussed and the remarkable linear relation between short-range correlations and teh EMC effect is reviewed. A convolution model that relates the underlying source of the EMC effect to modification of either the mean-field nucleons or the short-range correlated nucleons is presented. It is shown that both approaches are equally successful in describing the current EMC data.
The EMC Effect and High Momentum Nucleons in Nuclei
Hen, Or; Higinbotham, Douglas W.; Miller, Gerald A.; Piasetzky, Eli; Weinstein, Lawrence B.
2013-07-01
Recent developments in understanding the influence of the nucleus on deep-inelastic structure functions, the EMC effect, are reviewed. A new data base which expresses ratios of structure functions in terms of the Bjorken variable xA = AQ2/(2MA q0) is presented. Information about two-nucleon short-range correlations (SRC) from experiments is also discussed and the remarkable linear relation between SRC and the EMC effect is reviewed. A convolution model that relates the underlying source of the EMC effect to modification of either the mean-field nucleons or SRC nucleons is presented. It is shown that both approaches are equally successful in describing the current EMC data.
The EMC Effect and High Momentum Nucleons in Nuclei
Energy Technology Data Exchange (ETDEWEB)
Hen, Or; Higinbotham, Douglas; Miller, Gerald A; Piasetzky, Eliazer; Weinstein, Lawrence
2013-07-01
Recent developments in understanding the influence of the nucleus on deep-inelastic structure functions, the EMC effect, are reviewed. A new data base which expresses ratios of structure functions in terms of the Bjorken variable x{sub A}=AQ{sup 2}/(2M{sub A}q{sub 0}) is presented. Information about two-nucleon short-range correlations from experiments is also discussed and the remarkable linear relation between short-range correlations and the EMC effect is reviewed. A convolution model that relates the underlying source of the EMC effect to modification of either the mean-field nucleons or the short-range correlated nucleons is presented. It is shown that both approaches are equally successful in describing the current EMC data.
Multipole decomposition of the nucleon transverse phase space
LorcÃ©, C
2015-01-01
We present a complete study of the leading-twist quark Wigner distributions in the nucleon, discussing both the $\\mathsf T$-even and $\\mathsf T$-odd sector, along with all the possible configurations of the quark and nucleon polarizations. We identify the basic multipole structures associated with each distribution in the transverse phase space, providing a transparent interpretation of the spin-spin and spin-orbit correlations of quarks and nucleon encoded in these functions. Projecting the multipole parametrization of the Wigner functions onto the transverse-position and the transverse-momentum spaces, we find a natural link with the corresponding multipole parametrizations for the generalized parton distributions and transverse-momentum dependent parton distributions, respectively. Finally, we show results for all the distributions in the transverse phase space, introducing a representation that allows one to visualize simultaneously the multipole structures in both the transverse-position and transverse-m...
The Jefferson Lab 12 GeV program on nucleon structure
Energy Technology Data Exchange (ETDEWEB)
Burkert, Volker D. [JLAB
2013-10-01
This slide-show presents the experiments planned at JLab with their 12 GeV upgrade. Experiments reported address: the use of hadron spectra as probes of QCD; the transverse structure of hadrons; the longitudinal structure of hadrons; the 3-dimensional structure of hadrons; hadrons and cold nuclear matter; and low-energy tests of the Standard Model and fundamental symmetries.
Husimi distribution for nucleon tomography
Hatta, Yoshitaka
2015-01-01
We define the QCD Husimi distribution as the phase space distribution of partons inside the nucleon. Compared to the more well-known Wigner distribution, the Husimi distribution is better behaved and positive. It thus allows for a probabilistic interpretation and can be used to define the `entropy' of the nucleon as a measure of complexity of the partonic structure. A possible connection to the Color Glass Condensate approach at small-$x$ is also discussed.
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.
A-dependence of weak nuclear structure functions
Haider, H; Athar, M Sajjad
2013-01-01
Effect of nuclear medium on the weak structure functions $F_2^A(x,Q^2)$ and $F_3^A(x,Q^2)$ have been studied using charged current (anti)neutrino deep inelastic scattering on various nuclear targets. Relativistic nuclear spectral function which incorporate Fermi motion, binding and nucleon correlations are used for the calculations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, $F_i^A/F_i^{proton}$ and $F_i^A/F_i^{deuteron}$(i=2,3, A=$^{12}C$, $^{16}O$, $CH$ and $H_{2}O$) are obtained.
Measurement of the proton spin structure function g1p
International Nuclear Information System (INIS)
In order to check the Bjorken sum rule and confirm the EMC surprising conclusion on the spin structure of the proton, the measurement of the spin structure function of the proton has been performed by the Spin Muon Collaboration via the polarized muon nucleon deep inelastic scattering. The results of the 1993 run are presented within a kinematical range of 0.003 2 = 10 GeV2. The first moment of the polarized spin structure function g1p is found to be two standard deviations below the Ellis-Jaffe sum rule. Assuming SU(3) for hyperons ? decays, the quark spin contribution to the proton spin is extracted. Combining all available data on proton, neutron and deuton, The Bjorken sum rule is confirmed within 10%. (author). 25 refs., 3 figs., 2 tabs
Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order
International Nuclear Information System (INIS)
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 ci and di 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.)
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.)
New results from deep inelastic muon-nucleon scattering
International Nuclear Information System (INIS)
New results obtained by three distinct muon-nucleon scattering experiments are reviewed. They concern the F2 structure function measurements, the open and hidden charm production from multimuon events, and the evidence for forward jets and forward protons/antiprotons production from hadronic final states
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.
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
Structure functions at large x
International Nuclear Information System (INIS)
Structure function data, together with other measurements from fixed-target deep inelastic scattering and hadron-hadron collider experiments which contribute to our knowledge of the parton density functions, are reviewed. The inclusive cross-section measurements of neutral and charged current interactions at HERA are presented and their impact on the parton density functions is discussed. Future prospects for an improved knowledge of the parton density functions at large x are briefly mentioned. (author)
Structure in K--nucleon total cross sections below 1.1 GeV/c
International Nuclear Information System (INIS)
Total cross sections of K-p and K-d have been measured between 410 and 1070 MeV/c with high statistical precision. In addition to the well known ? (1520), ? (1820), and ? (1769), we confirmed the presence of the ? (1692) and the ? (1670). We have also observed several structures which could be Y* resonances: ? (1646), ? (1735), ? (1583), ? (1608), ? (1633), and ? (1715)
Neutron-star matter within the energy-density functional theory and neutron-star structure
Energy Technology Data Exchange (ETDEWEB)
Fantina, A. F.; Chamel, N.; Goriely, S. [Institut d' Astronomie et d' Astrophysique, CP226, Université Libre de Bruxelles (ULB), 1050 Brussels (Belgium); Pearson, J. M. [Dépt. de Physique, Université de Montréal, Montréal (Québec), H3C 3J7 (Canada)
2015-02-24
In this lecture, we will present some nucleonic equations of state of neutron-star matter calculated within the nuclear energy-density functional theory using generalized Skyrme functionals developed by the Brussels-Montreal collaboration. These equations of state provide a consistent description of all regions of a neutron star. The global structure of neutron stars predicted by these equations of state will be discussed in connection with recent astrophysical observations.
Neutron-star matter within the energy-density functional theory and neutron-star structure
International Nuclear Information System (INIS)
In this lecture, we will present some nucleonic equations of state of neutron-star matter calculated within the nuclear energy-density functional theory using generalized Skyrme functionals developed by the Brussels-Montreal collaboration. These equations of state provide a consistent description of all regions of a neutron star. The global structure of neutron stars predicted by these equations of state will be discussed in connection with recent astrophysical observations
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)
Chiral odd structure functions from a chiral soliton
International Nuclear Information System (INIS)
We calculate the chiral odd quark distributions and the corresponding structure functions hT(x,Q2) and hL(x,Q2) within the Nambu endash Jona-Lasinio chiral soliton model for the nucleon. The Q2 evolution of the twist-2 contributions is performed according to the standard GLAP formalism while the twist-3 piece bar hL(x) is evolved according to the large NC scheme. We carry out a comparison between the chiral odd structure functions of the proton and the neutron. At the low model scale (Q02) we find that the leading twist effective quark distributions f1(q)(x,Q02), g1(q)(x,Q02) and hT(q)(x,Q02) satisfy Soffer close-quote s inequality for both quark flavors q=u,d. copyright 1998 The American Physical Society
Nuclear structure functions in carbon near x=1
International Nuclear Information System (INIS)
Data from deep inelastic scattering of 200 GeV muons on a carbon target with squared four-momentum transfer 52 GeV2â‰¤Q2â‰¤200 GeV2 were analysed in the region of the Bjorken variable close to x=1, which is the kinematic limit for scattering on a free nucleon. At this value of x, the carbon structure function is found to be F2Câˆ¼1.2.10-4. The x dependence of the structure function for x>0.8 is well described by an exponential F2Câˆexp(-sx) with s=16.5Â±0.6. (orig.)
Neutrino Production of a Charmed Meson and the Transverse Spin Structure of the Nucleon.
Pire, B; Szymanowski, L
2015-08-28
We calculate the amplitude for exclusive neutrino production of a charmed meson on an unpolarized target in the collinear QCD approach, where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We demonstrate that the transversity chiral odd GPDs contribute to the transverse cross section if the hard amplitude is calculated up to order m_{c}/Q. We show how to access these GPDs through the azimuthal dependence of the Î½Nâ†’Î¼^{-}D^{+}N differential cross section. PMID:26371643
Nucleon spin-flavor structure in the SU(3)-breaking chiral quark model
International Nuclear Information System (INIS)
The SU(3) symmetric chiral quark model, which describes interactions between quarks, gluons, and the Goldstone bosons, explains reasonably well many aspects of the flavor and spin structure of the proton, except for the values of f3/f8 and ?3/?8. Introducing the SU(3)-breaking effect suggested by the mass difference between the strange and nonstrange quarks, we find that this discrepancy can be removed and better overall agreement obtained. copyright 1997 The American Physical Society
Tensor-polarized structure functions: Tensor structure of deuteron in 2020's
International Nuclear Information System (INIS)
We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones (F1, F2, g1, g2) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are b1, b2, b3, and b4 in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist- two functions are related by the Callan-Gross type relation b2 = 2xb1 in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of b1-4 from a hadron tensor W??. Second, a sum rule is explained for b1, and possible tensor-polarized distributions are discussed by using HERMES data in order to propose future experimental measurements and to compare them with theoretical models. A proposal was approved to measure b1 at the Thomas Jefferson National Accelerator Facility (JLab), so that much progress is expected for b1 in the near future. Third, formalisms of polarized proton-deuteron Drell-Yan processes are explained for probing especially tensor- polarized antiquark distributions, which were suggested by the HERMES data. The studies of the tensor-polarized structure functions will open a new era in 2020's for tensor-structure studies in terms of quark and gluon degrees of freedom, which are very different from ordinary descriptions in terms of nucleons and mesons
Nuclear Structure Functions at Low-$x$ in a Holographic Approach
Agozzino, L; Colangelo, P
2014-01-01
Nuclear effects in deep inelastic scattering at low$-x$ are phenomenologically described changing the typical dynamical and/or kinematical scales characterizing the free nucleon case. In a holographic approach, this rescaling is an analytical property of the computed structure function $F_2(x,Q^2)$. This function is given by the sum of a conformal term and of a contribution due to quark confinement, depending on IR hard-wall parameter $z_0$ and on the mean square distances, related to a parameter $Q^\\prime$, among quarks and gluons in the target. The holographic structure function per nucleon in a nucleus $A$ is evaluated showing that a rescaling of the typical nucleon size, $z_0$ and $Q^\\prime$, due to nuclear binding, can be reabsorbed in a $Q^2$-rescaling scheme. The difference between neutron and proton structure functions and the effects of the longitudinal structure functions can also be taken into account. The obtained theoretical results favourably compare with the experimental data.
Nucleon Magnetic Moments and Electric Polarizabilities
Detmold, William; Tiburzi, Brian C.; Walker-Loud, Andre
2010-01-01
Electromagnetic properties of the nucleon are explored with lattice QCD using a novel technique. Focusing on background electric fields, we show how the electric polarizability can be extracted from nucleon correlation functions. A crucial step concerns addressing contributions from the magnetic moment, which affects the relativistic propagation of nucleons in electric fields. By properly handing these contributions, we can determine both magnetic moments and electric polari...
Nucleon form factors, generalized parton distributions and quark angular momentum
International Nuclear Information System (INIS)
We extract the individual contributions from u and d quarks to the Dirac and Pauli form factors of the proton, after a critical examination of the available measurements of electromagnetic nucleon form factors. From this data we determine generalized parton distributions for valence quarks, assuming a particular form for their functional dependence. The result allows us to study various aspects of nucleon structure in the valence region. In particular, we evaluate Ji's sum rule and estimate the total angular momentum carried by valence quarks at the scale ?=2 GeV to be Juv=0.230+0.009-0.024 and Jdv=-0.004+0.010-0.016.
International Nuclear Information System (INIS)
In the framework of the Quantum Chromodynamics (QCD), the nucleon is described as being composed of three valence quarks surrounded by a sea of virtual quark-antiquark pairs and gluons. If the role of this virtual sea in the nucleon properties is inferred to be important, this contribution is still poorly understood. In this context, we study the role of the strange quarks in the nucleon since this is the lightest quark flavor of the sea with no valence contribution. We are determining its contribution to the charge and magnetization distributions in the nucleon via parity violation experiments. The measurement is performed by elastically scattering polarized electrons from nucleon target. A world wide program in which the G0 experiment takes place has been performing for a decade. The G0 experiment and the analysis of the results from its forward angles phase are the topics of this thesis. This document presents the physics case of the strangeness content of the nucleon (mass, spin, impulsion). It describes also the formalism related to the electroweak probe and the form factors, and then the principle of parity violating asymmetry measurement. The G0 experimental setup, which was built and installed in the Hall C of the Jefferson Laboratory (Usa), is detailed. This set-up was designed for the measurement of asymmetries of the order of 10-6 with an overall relative uncertainty better than 10 %, over a momentum transfer range 0.1-1 (GeV/c)2. The various steps of the data analysis are exposed. They have allowed us to start from measured counting rates to reach parity violating physics asymmetries. This required a careful treatment of the various sources of systematical errors which is discussed extensively. Finally the results from the G0 forward angle measurement, its comparison with others experiments and with theoretical models, are presented. They support a non null strange quark contribution. (author)
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...
Strangeness in proton and properties of nucleons in nuclear matter revisited
Chandar, A; Chakrabarti, B
2013-01-01
The properties of the nucleons in nuclear medium have been investigated in the context of the flux tube model incorporating strangeness $(s\\bar{s})$ contribution to proton structure in conformity with the experimental indication. Proton is described as a pentaquark system with strange quark contribution whereas neutron is described in three quark configuration. The Quasi particle model of diquark is used to describe the structures of the nucleons. Modifications of the properties like swelling, mass, incompressibility, ratio of the structure functions ($\\frac{F_{2}^{n}(x)}{F_{2}^{p}(x)}$), Gottfried Sum rule for nucleons in nuclear medium have been studied and significant effects have been observed. It has been suggested that the change of the size degree of freedom of the nucleon in the nuclear medium plays an important role in describing the properties in medium. The results are discussed in detail and compared with existing experimental and theoretical predictions. Some interesting observations are made.
Nucleon mass dependence of the central nucleon-nucleon potential
Energy Technology Data Exchange (ETDEWEB)
Higa, Renato; Robilotta, Manoel Roberto [Sao Paulo Univ. (USP), SP (Brazil). Inst. de Fisica
2000-07-01
Full text follows: In this work we analyse the nucleon mass dependence of the central component of the nucleon-nucleon potential at large distances, derived from a relativistic effective chiral Lagrangian. This component is directly related to the nucleon scalar form factor and describes the energy density of its mesonic cloud. Results considering only pionic processes, consistent with the Argonne potential, show that the heavy baryon limit is about 30% larger than those with the nucleon mass at its experimental value, and therefore to have realistic descriptions of the NN system this mass must remain finite. Further discussions concerning the delta resonance as well as the strangeness sector, due to the exchange of two uncorrelated kaons, is also presented. (author)
Spin observables in nucleon-nucleus scattering
Energy Technology Data Exchange (ETDEWEB)
Moss, J.M.
1982-01-01
The curse of inelastic nucleon scattering and charge exchange has always been the enormous complexity of the nucleon-nucleon (N-N) interaction. This complexity, however, can also be viewed as the ultimate promise of nucleons as probes of nuclear structure. Given an adequate theoretical basis, inelastic nucleon scattering is capable of providing information not obtainable with other probes. Recently a revolution of experimental technique has taken place that makes it desirable to re-examine the question of what physics is ultimately obtainable from inelastic nucleon scattering. It is now feasible to perform complete polarization transfer (PT) experiments for inelastic proton scattering with high efficiency and excellent energy resolution. Programs to measure PT obsevables are underway at several laboratories, and results are beginning to appear. Objectives of this presentation are to examine how such experiments are done, and what physics is presently obtained and may ultimately be learned from them.
Spin observables in nucleon-nucleus scattering
International Nuclear Information System (INIS)
The curse of inelastic nucleon scattering and charge exchange has always been the enormous complexity of the nucleon-nucleon (N-N) interaction. This complexity, however, can also be viewed as the ultimate promise of nucleons as probes of nuclear structure. Given an adequate theoretical basis, inelastic nucleon scattering is capable of providing information not obtainable with other probes. Recently a revolution of experimental technique has taken place that makes it desirable to re-examine the question of what physics is ultimately obtainable from inelastic nucleon scattering. It is now feasible to perform complete polarization transfer (PT) experiments for inelastic proton scattering with high efficiency and excellent energy resolution. Programs to measure PT obsevables are underway at several laboratories, and results are beginning to appear. Objectives of this presentation are to examine how such experiments are done, and what physics is presently obtained and may ultimately be learned from them
Tensor optimized shell model with bare nucleon-nucleon interaction for 4He
Myo, Takayuki; Ikeda, Kiyomi
2009-01-01
The pion exchange between nucleons generates a strong tensor interaction, which provides large attractive contribution for the binding energy of nucleus. This non-central tensor interaction is difficult to handle in the shell model framework, which hinders full understanding of nuclear structure. We develop the tensor optimized shell model (TOSM) for the strong tensor interaction and now we are able to use bare nucleon-nucleon interaction with the help of the unitary correlation operator method (UCOM) for the short range hard core. We adopt the nucleon-nucleon interaction, AV8', and calculate explicitly the ground state of 4He and make a detailed comparison with rigorous few-body model calculations. We show a large amount of success of the tensor optimized shell model with bare nucleon-nucleon interaction for 4He.
Dilepton production in nucleon-nucleon interactions
International Nuclear Information System (INIS)
Starting from a realistic one-boson-exchange model fitted to the amplitudes of elastic nucleon-nucleon scattering and the process NN?N? we perform a fully relativistic and gauge-invariant calculation for the dilepton production in nucleon-nucleon collisions, including the important effect of propagating the ?-resonance. We compare the results of our calculations with the latest experimental data on dilepton production. We also show how to implement various electromagnetic form factors for the hadrons in our calculations without losing gauge invariance and discuss their influence on dilepton spectra. ((orig.))
International Nuclear Information System (INIS)
We discover an inner structure of QED while the gauge potential is decomposed into two orthogonal components. Based on this, the Lagrangian of the electron-photon system is expanded to a new form and by the general method of field theory, the gauge invariant spin and orbital angular momentum operators of the electron and photon are naturally obtained from Noether's theorem. Our method, which can be generalized to the non-Abelian systems to investigate the inner structure of QCD, provides a new perspective to look on the nucleon spin crisis and opens a window into a strict and systematic resolution of this long-standing problem.
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.
Nucleon Spin - Results from Jefferson Lab
Kuhn, Sebastian
2013-10-01
Over thirty years after the first experiments probed the spin structure of the nucleon, the pace of experimental and theoretical exploration of this subject keeps increasing. During its fifteen-year run with beam energies up to 6 GeV, Jefferson Lab has made many important contributions to this field - from measurements of the inclusive spin structure functions of the proton and the neutron over a wide kinematic range to seminal experiments accessing the three-dimensional nucleon spin structure through Generalized Parton Distributions and Transverse Momentum Dependent structure functions. An even brighter future lies ahead - after the 12 GeV upgrade, Jefferson Lab will completely map the spin-dependent parton distribution functions for all quark flavors in the valence region. In this talk, I will present an overview of this program, with special emphasis on recent and forthcoming results from the 6 GeV run and a glimpse of the future program with 12 GeV. Supported by DOE grant DE-FG02-96ER40960.
International Nuclear Information System (INIS)
Two-particle correlation functions were measured for the emission of protons, deuterons, tritons, ?, and lithium fragment at small relative momenta in 40Ar-induced reactions on 197Au at 25 MeV/nucleon. Based on three-body trajectory calculations the emission time scales for the particles were extracted from p-d, d-d, t-t, and lithium-lithium correlation functions.The mean emission time was found to decrease with increasing sum of the kinetic energies of the particle in a correlated pairs, indicating the emission of more energetic particles at earlier stages of the reaction than at later stages. The time scale for the emission of lithium fragments emission suggests that sequential binary disassembly occurs in 40Ar+197Au reaction at MeV/nucleon. The mean emission temperatures of 3.5+1.3-0.8 and 3.6±0.4 MeV were also extracted from the relative populations of the excited and ground states of the respective emitted nuclides 8Be and 4He. (orig.)
Direct instantons in QCD nucleon sum rules
Forkel, H; Forkel, Hilmar; Banerjee, Manoj K.
1993-01-01
We study the role of direct (i.e. small-scale) instantons in QCD correlation functions for the nucleon. They generate sizeable, nonperturbative corrections to the conventional operator product expansion, which improve the quality of both QCD nucleon sum rules and cure the long-standing stability problem, in particular, of the chirally odd sum-rule.
Nucleon momentum and density distributions of nuclei
International Nuclear Information System (INIS)
In the framework of recently suggested density coherent fluctuations model the nucleon momentum and density distributions are examined. Nucleon momentum and density distributions are expressed in terms of the fluctuation's function, experimentally obtainable from the elastic electron-nuclei scattering. (author)
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)
Study of nucleon-nucleon and hyperon-nucleon interaction
International Nuclear Information System (INIS)
In this paper we review recent investigations of nucleon-nucleon and hyperon-nucleon interactions employing a non-relativistic quark cluster model. We concentrate mainly on the short and medium-range behavior of the baryon-baryon interaction based on the one-gluon and meson exchange potentials. The chiral quark model based on pion and sigma exchange between quarks is also discussed. We also review a study of the deuteron and its electromagnetic properties in a quark model with exchange currents. (author)
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; ...
Sauer, Peter U
2014-01-01
The role of three-nucleon forces in ab initio calculations of nuclear systems is investigated. The difference between genuine and induced many-nucleon forces is emphasized. Induced forces arise in the process of solving the nuclear many-body problem as technical intermediaries towards calculationally converged results. Genuine forces make up the Hamiltonian; they represent the chosen underlying dynamics. The hierarchy of contributions arising from two-, three- and many-nucleon forces is discussed. Signals for the need of the inclusion of genuine three-nucleon forces are studied in nuclear systems, technically best under control, especially in three-nucleon and four-nucleon systems. Genuine three-nucleon forces are important for details in the decription of some observables. Their contributions to observables are small on the scale set by two-nucleon forces.
A study of the ground-state energy of 4He with nucleon-nucleon potentials
International Nuclear Information System (INIS)
Ground-state properties are evaluated for the finite nucleus 4He starting from realistic nucleon-nucleon interactions within the framework of the Green's function approach. For the sake of comparison, the same calculations are performed using the Brueckner-Hartree-Fock approximation. For that purpose four high-quality modern nucleon-nucleon interactions represented in momentum space are employed: the Argonne V18, CD-Bonn, Bonn A and N3LO potentials. In these potentials, the effects of charge dependence are taken into account. Additional binding energy is obtained from the inclusion of the hole-hole scattering term within the framework of the Green function approach. It has been shown that the Green function results agree well with the results obtained by accurate methods for few-nucleon systems such as the Faddeev-Yakubovsky calculation. In this study, a comparison of the calculated ground-state energies, obtained by using the Green function approach and different nucleon-nucleon potentials, with experimental values is carried out. The results show good agreement between the calculated values and the experimental ones. - Highlights: ? We present ground-state energies of the helium nucleus. ? We consider four high-quality modern nucleon-nucleon potentials. ? It is shown that the Green function approach gives quite good results.
Theory of diffractive structure functions
International Nuclear Information System (INIS)
We discuss the connection between the dipole approach and the DIS structure functions. Particular emphasis is given to DIS diffraction. We report on current work on the NLO photon impact factor. As an application of the dipole approach in DIS diffraction, we discuss the diffractive production of jets and of charm. (author)
Polarized target for nucleon-nucleon experiments at Saturne II
International Nuclear Information System (INIS)
Continuous improvements of SATURNE polarized target resulted in a flexible and reliable facility for spin physics. For polarized neutron target, two cartridges loaded with 6LiD and 6LiH are set in the refrigerator and can be quickly inserted in the beam. The polarized proton target is a 70 cm3 cartridge loaded with Pentanol-2, a promising material according to the results obtained. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon-nucleon scattering is shown for different targets. copyright 1995 American Institute of Physics
Dynamical rescaling, the EMC effect and universality of hadron structure functions
International Nuclear Information System (INIS)
Data are compared on the EMC effect, with the hypothesis that the quark confinement size increases in going from a free nucleon to a nucleus. In QCD a dynamical rescaling is predicted: Q2 variation of the distribution function in a given target parallels the dependence on confinement size, R, at fixed Q2. Thus a dynamical scale invariance obtains when both R and Q2 are varied, yielding the dynamical rescaling relation F2sup(A)(x, Q2) = F2sup(N)(x, zetaQ2) where zeta > 1 is predicted for any nucleus and is a function of the confinement size. Data on 12 nuclei agree with this, implying that confinement size is governed by nuclear density. The formalism is tested by relating the pion and nucleon structure functions. (author)
Production cross sections of dimuons and experimental analysis of hadronic structure functions
International Nuclear Information System (INIS)
Analysis, by spectrometry (spectrometer Lezard NA3), of the particle structure (nucleons, mesons) and determination of a multiplicative factor (nearly 2) for the Drell-Yan cross section. Description of the experimental apparatus, production of dimuons on hydrogen and heavy nuclei (platinum), exploration of the nucleon (by inelastic diffusion of leptons, especially neutrinos, and use of the parton model), utilization of the Drell-Yan mechanism describing the production of a continuous spectrum of muons pairs (with experimental test), study of the effects (and subsequent corrections) of the quantum chromodynamics on the amplitude of the strong coupling and on the evolution of the hadronic structure observed as a function of the sensor energy, and at last, after presenting how data are processed analysis of the hadronic structure appearing during the pair production of muons of great masses (4.2< MÎ¼Î¼<8,5 GeV)
Nucleon-nucleon dynamics at medium energies. Pt. 1
International Nuclear Information System (INIS)
A framework is presented for a unified theory of elastic nucleon-nucleon scattering and single-pion production at medium energies. The model is relativistic, unitary, and takes into account all spin complications. In the simplest version of the theory the driving mechanism is one-pion exchange but the model can be extended to include short-range forces. The resulting set of coupled linear integral equations have the structure of three-body equations and can be solved exactly. The method of solution is discussed. (orig.)
Precision measurement of the neutron spin dependent structure functions
International Nuclear Information System (INIS)
In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g1n (x, Q2) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized 3He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 ? x ? 0.7 with an average Q2 of 5 GeV2. The author reports the integral of the spin dependent structure function in the measured range to be ?0.0140.7 dx g1n(x, 5 GeV2) = -0.036 ± 0.004(stat.) ± 0.005(syst.). The author observes relatively large values of g1n at low x that call into question the reliability of data extrapolation to x ? 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g1p and g1n paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q2 = 5 GeV2, determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule
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)
Bound-state quark and gluon contributions to structure functions in QCD
International Nuclear Information System (INIS)
One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: ''intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and ''extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic ''bound-valence'' and extrinsic ''non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs
Quark sea asymmetry of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Mirez, Carlos; Tomio, Lauro [Instituto de Fisica Teorica, Universidade Estadual Paulista-Unesp, Rua Dr. Bento Teobaldo Ferraz, 271, Barra-Funda, 01140-070, Sao Paulo, SP (Brazil); Trevisan, L.A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Frederico, T. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, CTA, 12228-900, Sao Jose dos Campos, SP (Brazil)
2010-02-15
The light anti-quark and quark distribution in the proton, as well as the neutron to proton ratio of the structure functions, extracted from experimental data, are well fitted by a statistical model of linear-confined quarks. The parameters of the model are given by a temperature, which is adjusted by the Gottfried sum-rule violation, and two chemical potentials given by the corresponding up (u) and down (d) quark normalizations in the nucleon. The quark energy levels are generated by a relativistic linear-confined scalar plus vector potential.
On the nucleon–nucleon scattering phase shifts through supersymmetry and factorization
Indian Academy of Sciences (India)
U Laha; J Bhoi
2013-12-01
By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase shifts and demonstrate the usefulness of our constructed potentials by means of model calculation.
Nucleon–nucleon scattering in the light of supersymmetric quantum mechanics
Indian Academy of Sciences (India)
J Bhoi; U Laha; K C Panda
2014-05-01
By exploiting supersymmetry-inspired factorization method together with a judiciously chosen deuteron ground-state wave function, approximate higher partial wave nucleon–nucleon potentials are generated. In this context, a minor modification is also introduced to the generated potentials. The n–p scattering phase shifts are computed and analysed via the phase function method.
Levon, A I
2011-01-01
Conflicting coupling of unpaired nucleons in the odd-odd nuclei is discussed. A very simple explanation is suggested for the damping of the energy spacing of the lowest levels in the rotational bands in the odd-odd nuclei in the case of a "conflicting" coupling of the odd proton and neutron comparative to those of the bands based on the state of the strongly-coupled particle in the neighbouring odd nuclei entering the "conflicting" configuration.
On the nucleon association theory in light nuclei
International Nuclear Information System (INIS)
A new approach to the problem of the association of nucleons in light nuclei is discussed. It is based on the assumption that the same nucleon can simultaneously be a part of several strongly correlated groups of nucleons (clusters). In the framework of this approach a uniform scheme is proposed to construct the ground state wave function of several light nuclei (42+ and H-
Hupin, Guillaume; Navrátil, Petr
2014-01-01
Prototype for the study of weakly bound projectiles colliding on stable targets, the scattering of deuterium ($d$) on $^4$He ($\\alpha$) is an important milestone in the search for a fundamental understanding of low-energy reactions. At the same time, it is also important for its role in the Big-bang nucleosynthesis of $^6$Li and applications in the characterization of deuterium impurities in materials. We present the first unified {\\em ab initio} study of the $^6$Li ground state and $d$-$^4$He elastic scattering using two- and three-nucleon forces derived within the framework of chiral effective field theory. The six-nucleon bound-state and scattering observables are calculated by means of the no-core shell model with continuum. %and are compared to available experimental data. We analyze the influence of the dynamic polarization of the deuterium and of the chiral three-nucleon force, and examine the role of the continuum degrees of freedom in shaping the low-lying spectrum of $^6$Li. We find that the adopted...
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...
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...
Structure functions in ?-->3?? decay
Xiong, Zhaohua; Chen, Guoming; Chen, Hesheng
1999-01-01
The structure functions in the ?-->3?? decay are extracted using the model proposed by Li. We compare the predictions of the Li model with the KS ones and the data from the OPAL experiment, and find that predictions by the model for wA(Q2) are consistent with the data except for in the high energy region (Q2>1.2 GeV2), and wC,wD,wE normalized to wA are in reasonable agreement with the experimental results. A running mass function of ma1 is proposed to the model.
Universality of nucleon-nucleon short-range correlations and nucleon momentum distributions
Alvioli, Massimiliano; Kaptari, Leonid P; Mezzetti, Chiara Benedetta; Morita, Hiko
2013-01-01
By analyzing recent microscopic many-body calculations of few-nucleon systems and complex nuclei performed by different groups in terms of realistic nucleon-nucleon (NN) interactions, it is shown that NN short-range correlations (SRCs) have a universal character, in that the correlation hole that they produce in nuclei appears to be almost A-independent and similar to the correlation hole in the deuteron. The correlation hole creates high-momentum components, missing in a mean-field (MF) description and exhibiting several scaling properties and a peculiar spin-isospin structure. In particular, the momentum distribution of a pair of nucleons in spin-isospin state $(ST)=(10)$, depending upon the pair relative ($k_{rel}$) and center-of-mass (c.m.) ($K_{c.m.}$) momenta, as well as upon the angle $\\Theta$ between them, exhibits a remarkable property: in the region $k_{rel}\\gtrsim 2\\,fm^{-1}$ and $K_{c.m.}\\lesssim 1\\,fm^{-1} $, the relative and c.m. motions are decoupled and the two-nucleon momentum distribution fa...
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.
Measuring spin-dependent structure functions at CEBAF
International Nuclear Information System (INIS)
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 Q2 dependence of the spin-dependent structure functions g1(x) and G2(x) and (2) the by far most precise determination of the third moments of g1(x) and g2(x) the latter of which the author argues to be related to a fundamental property of the nucleon
Structure and Function of Glucansucrases
Dijkstra, B. W.; Vuji?i?-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 ?-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.
Structure function tests of QCD
International Nuclear Information System (INIS)
The problems involved in comparing QCD predictions with the Q2 evolution of deep inelastic structure functions are discussed. These involve the resummation of higher order terms approximately equal to (?sub(s) ln(1-z))sup(s) and the use of QCD perturbative analysis in the timelike domain. A comparison is made between theory and experiment for various QCD predictions with and without resummation of the dangerously large terms. The implications for the value of lambda are considered. (author)
On the photon structure function
International Nuclear Information System (INIS)
The solution of the inhomogeneous evolution equations for the parton distributions of the photon in moment space with a general Born term and three arbitrary energy parameters has been investigated. In some special cases, the general solution can be reduced to the formulas which have been obtained by the previous papers. The differences between our result and those given by the previous papers for the photon structure function are significant not only numerically, but also in singularity behavior. (author). 10 refs
International Nuclear Information System (INIS)
We review experimental results concerning polarization phenomena in nucleon-nucleon scattering in which both the elastic scattering and hadron-production reaction are included. We also present summary of S = 0 dibaryon resonances and candidates by reviewing experimental data in the nucleon-nucleon system, ?d channel, ?d elastic scattering, pp ? ?d channel, deuteron break-up reactions, and narrow structures in missing-mass spectra. 93 refs., 26 figs
Pauli blocking effects for nucleon-nucleus scattering
International Nuclear Information System (INIS)
Theoretical predictions for nucleon-nucleus scattering are customarily based on multiple-scattering formalisms in which the projectile-nucleon--struck-target-nucleon two-body subsystem is antisymmetrized and in which the target wave function is antisymmetric with respect to the nucleon constituents. Although formalisms exist for nucleon-nucleus scattering which account for full (A+1)-body antisymmetrization, these theories have not been adequately implemented in numerical applications. Pauli blocking of the struck target nucleon in intermediate scattering states is implicitly included in standard optical potential calculations which consistently include terms through second-order in the projectile-target nucleon scattering t matrix. In this work the multiple scattering expansion of the fully antisymmetrized nucleon-nucleus optical potential is organized so as to make explicit corrections to the standard optical potential due to Pauli blocking of the projectile nucleon in intermediate scattering states. Numerical calculations are presented for the resulting density dependent, projectile-target nucleon effective interaction and comparison with a previous density dependent model is given. It is shown that density dependent effective interaction t matrices for nucleon-nucleus scattering calculations should include Pauli blocking of just the projectile nucleon and binding potential corrections for just the target nucleon
Proton and neutron polarized targets for nucleon-nucleon experiments at SATURNE II
International Nuclear Information System (INIS)
A SATURNE polarized target has been used for nucleon-nucleon elastic scattering and transmission experiments for 15 years. The polarized proton target is a 70 cm3 cartridge loaded with Pentanol-2. For polarized neutron target, two cartridges loaded with 6LiD and 6LiH are set in the refrigerator and can be quickly inserted in the beam. First experiments using 6Li products in quasielastic pp or pn analyzing power measurements are compared with the same observables measured in a free nucleon-nucleon scattering using polarized proton targets. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon-nucleon scattering is shown for different targets. (author)
Proton and neutron polarized targets for nucleon-nucleon experiments at SATURNE II
Energy Technology Data Exchange (ETDEWEB)
Ball, J.; Combet, M.; Sans, J.L. [Laboratoire National Saturne, Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Benda, B.; Chaumette, P.; Deregel, J.; Durand, G.; Dzyubak, A.P.; Gaudron, C.; Lehar, F. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; Janout, Z.; Khachaturov, B.A. [Joint Inst. for Nuclear Research, Dubna (Russian Federation). Lab. of Nuclear Problems] [and others
1996-12-31
A SATURNE polarized target has been used for nucleon-nucleon elastic scattering and transmission experiments for 15 years. The polarized proton target is a 70 cm{sup 3} cartridge loaded with Pentanol-2. For polarized neutron target, two cartridges loaded with {sup 6}LiD and {sup 6}LiH are set in the refrigerator and can be quickly inserted in the beam. First experiments using {sup 6}Li products in quasielastic pp or pn analyzing power measurements are compared with the same observables measured in a free nucleon-nucleon scattering using polarized proton targets. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon-nucleon scattering is shown for different targets. (author). 15 refs.; Submitted to Nuclear Instruments and Methods (NL).
Measurement of the spin-dependent structure function g1 of the deuteron at SLAC
International Nuclear Information System (INIS)
Deep-inelastic scattering measurements were performed at SLAC with 29 GeV polarized electrons incident on longitudinally and transversely polarized deuterons to obtain the spin-dependent structure function gd1. The high-statistics data cover the kinimatical range of xBj > 0.03 and 1 2 2. The deuteron spin-structure function gd1 and the integral ?10 gd1dx will be presented, as well as results for the fraction of nucleon helicity carried by quarks
International Nuclear Information System (INIS)
Two theoretical approaches to extract the neutron structure functions from combined experimental data on the proton and deuteron are considered. It is shown that the consideration only of the Fermi motion of nucleons in the deuteron in the light cone kinematics gives wrong results at large x (x > 0.7). The meson exchange corrections and binding effects in the deuteron must be taken into account. A new treatment of the experimental neutron structure function obtained from BCDMS-collaboration data is given. (author). 18 refs, 4 figs, 2 tabs
Pionic background for nucleon-nucleon observables
International Nuclear Information System (INIS)
We present a method that allows the unambiguous definition of the one-pion exchange contribution to nucleon-nucleon scattering observables, and then use it to determine those waves where values of phase shifts and mixing parameters may be understood as sums of pionic and non-pionic dynamical effects. This helps the assessment of the explicative power of the various existing phenomenological potentials and may eventually lead to ways of discriminating their effectiveness. (author)
Pionic background for nucleon-nucleon observables
International Nuclear Information System (INIS)
A method is presented that allows the unambiguous definition of the one pion exchange contribution to nucleon-nucleon scattering observables and then use it to determine those waves where values of phase shifts and mixing parameters may be understood as sums of pionic and non-pionic dynamical effects. This helps the assessment of the explicative power of the various existing phenomenological potentials and may eventually lead to ways of discriminating their effectiveness. (author) 16 refs.; 19 figs.; 2 tabs
Nucleon properties from unconventional interpolating fields
International Nuclear Information System (INIS)
Interpolating fields, used to excite hadrons from the QCD vacuum in nonperturbative field-theoretic investigations of hadron properties, are explored with an emphasis on unconventional nucleon interpolators. The QCD continuum model for excited state contributions to QCD correlation functions is a central element in extracting the physics contained in these alternate correlation functions. The analysis confirms the independence of nucleon properties obtained from different interpolating fields. However, this independence comes about in a trivial manner. These results provide a resolution to the long standing debate over the optimal nucleon interpolating field to be used in QCD sum rule analyses
Nucleon pair approximation description of the low-lying structure of $^{108,109}$Te and $^{109}$I
Jiang, H; Lei, Y; Liotta, R; Wyss, R; Zhao, Y M
2013-01-01
The low-lying level schemes and electromagnetic transitions of $^{109}$Te, $^{109}$I, and the neighboring even-even nucleus $^{108}$Te, are calculated within the framework of the $SD$-pair approximation of the nuclear shell model. Good agreement is obtained between the calculated results and experimental data. The favored components of low-lying bands are discussed in the collective nucleon-pair subspace. The weak-coupling picture shown in these nuclei and its relationship with residual quadrupole-quadrupole interaction between valence protons and neutrons are analyzed.
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.
Electromagnetic form factors of nucleons and Delta*
Li, BingAn
2000-01-01
A relativistic quark model and a new set of wave functions of nucleon and Delta have been used to study the electromagnetic propertities of (1/2)^+ baryons and photoelectric production of Delta(1236).
International Nuclear Information System (INIS)
The structure of the neutron rich light nuclei 11Be and 10Li has been investigated by means of one nucleon transfer reactions. The experiments have been carried out at GANIL in inverse kinematics using 11Be secondary beams. The 11Be(p,d)10Be reaction bas been studied at 35.3 MeV/u. The 10Be ejectiles were analyzed by the spectrometer SPEG, and coincident deuterons were detected in the position sensitive silicon detector CHARISSA. Transfer cross sections to 0+1 and 2+1, states in 10Be were measured up to ?CM = 16 deg. and compared to DWBA and CRC predictions. The effects of neutron-cure couplings on reaction form factors have been studied by solving coupled equations in the framework of a vibrational model. It is shown that the rate of core excitation 10Be2+ in the 11Begs wave function is overestimated by a standard analysis with form factors given by the usual Separation Energy prescription. The former model predicts a rate of core excitation of 16% and leads to theoretical cross sections which are in good agreement with the experimental data. The aim of the 11Be(d,3He)10Li experiment, realized at 37 MeV/u, was to measure the distribution of the 2s neutron strength in the unbound nucleus 10Li. The energy spectrum was deduced from the 3He energy and angle measured by the silicon strip detector array MUST. An asymmetric peak is clearly observed near the threshold, with a maximum at -Sn = 130 keV. This constitutes a direct proof of the inversion of 2s and 1p1/2 shells in 10Li, which was until now a controversial question in spite of many experimental efforts. On the other band the analysis of the 11Be(d,t)10Be reaction studied in the same experiment confirms the results obtained in the 11Be(p,d)10Be reaction concerning the 11Begs structure. This work shows the interest and feasibility of studies of the shell properties of exotic nuclei using transfer reactions induced by radioactive beams and constitutes the beginning of a program devoted to this kind of experiment. (author)
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.
Nuclear structure function F2A: Moments Mn(F2A) and kinematics beyond x=1
International Nuclear Information System (INIS)
An analysis of the behavior of nuclear structure functions F2A at large x and their moments MnA at large n has been performed within two theoretical approaches: (i) the QCD-motivated Q2-rescaling model and (ii) the operator product expansion method within an effective meson-nucleon theory which is prompted by nuclear physics. Our theoretical estimates of the nuclear structure function at x?1 are in good agreement with existing data. The moments, derived from experimental data, are found to depend essentially on the behavior of the respective structure functions beyond x=1. A relation between the Q2-rescaling parameter ?A and nuclear averages, i.e., mean kinetic energy and chemical potential of nucleons, as well as a dependence of ?A on n are established
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...
A Study of Nucleon Spin Struture from Quantum Chromodynamics
Osborne, Jonathan
2001-01-01
I present an introduction to the field of Quantum Chromodynamics (QCD) with emphasis on nucleon spin structure and perturbative methods. After a somewhat comprehensive overview of perturbative QCD, including the systematics of renormalization, I introduce deeply-inelastic scattering and deeply-virtual Compton scattering along with the nonperturbative distribution functions appearing in these processes. I show how these processes can be used to extract the distribution of longitudinal spin of ...
Nucleon and flavor form factors in a light front quark model in AdS/QCD
Chakrabarti, Dipankar; Mondal, Chandan(Department of Physics, Indian Institute of Technology Kanpur, 208016, Kanpur , India)
2013-01-01
Using the light front wave functions for the nucleons in a quark model in AdS/QCD, we calculate the nucleon electromagnetic form factors. The flavor decompositions of the nucleon form factors are calculated from the GPDs in this model. We show that the nucleon form factors and their flavor decompositions calculated in AdS/QCD are in agreement with experimental data.
Role of the nucleon virtual mass in quark distributions of nuclei
International Nuclear Information System (INIS)
A simple model which allows explicit calculations of the nuclear structure function in terms of the nucleon structure function for the deuteron as well as heavier nuclei is proposed. The impulse approximation in the DIS which leads to the convolution form of the nuclear structure function is examined and forms the basis of the model. The nucleus is viewed as a bound state of nucleons in constant motion with virtual mass less than the mass of a free nucleon. The EMC effect is discussed in the context of the model. Quantitative agreement with the nuclear DIS data is obtained. It was found that most of the nucleus momentum fraction is carried by the nucleons while a small portion is carried by other constituents presumed to be responsible for binding. The momentum fraction of these binding constituents showed saturation behavior similar to that found for the Fermi momentum as the atomic mass number of the nucleus increases, thereby suggesting a relationship between the two. Comparison is made between the model and other possible EMC effect interpretations. Lastly, a decisive test for the convolution form in general and the nuclear virtual mass, in particular, is provided. As predicted by the model, the ratio of nuclear to nucleon Q2- moments are shown to be Q2-independent and the values of this ratio for various nuclei are given
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Experimental results on the multiplicity distributions of various particles produced in the interactions of 7Li with emulsion nuclei at a momentum of 3 GeV/c per projectile nucleon are reported. A comparison with data on collisions induced by other nuclei at a nearly identical momentum per nucleon is presented in order to reveal the dependence on the projectile mass. The internal structure of 7Li is explored by studying the projectile fragment.The mean multiplicity of shower particles, s>, induced by 7Li is found to be less than that in the case of 6Li projectiles. The angular distributions of target fragments and relativistic charged secondaries are investigated. No shock-wave phenomena are observed. Forward-to-backward ratios are calculated for each case. The probability distributions for relativistic secondaries produced per unit rapidity are studied in detail, along with the rapidity densities and their dependence on the projectile and the target mass. A comparison of the angular spectra of shower particles produced in central and peripheral collisions supports the limiting-fragmentation hypothesis. The collisions in question seem to become more central with increasing shower-particle multiplicity
Low x physics, deep inelastic scattering and structure functions
Energy Technology Data Exchange (ETDEWEB)
Feltesse, J.
1994-12-31
HERA experiments together with polarised fixed target lepton-nucleon scattering experiments and hadron-hadron interactions have provided this year a wealth of new results on the structure of the proton and on low x physics where x is the fraction of nucleon momentum carried by the struck quark in lepton scattering. Measurement o the W charge asymmetry in CDF at FNAL has provided new constraints on the d/u ratio in the proton. The Drell-Yan asymmetry ({sigma}{sub pp} - {sigma}{sub pn})/({sigma}{sub pp} + {sigma}{sub pn}) measured by the NA51 experiment at CERN confirms that there are more of anti d than anti u in the proton. New data on proton, deuteron and neutron polarized structure functions from the SLAC E143 and CERN SMC experiments are in good agreement. The naive Ellis-Jaffe sum rule is violated by at least two standard deviations and the Bjorken Sum rule is verified to within about 10%. The measured QCD corrections to the Bjorken Sum Rule using the low Q{sup 2} data from E143 provide a new method to determine the QCD running coupling constant {alpha}{sub 5}. Combining fixed target data from E665 and FNAL and HERA results from H1 and ZEUS, the measurements of the proton structure function F{sub 2}(x,Q{sup 2}) cover the very large kinematic range of 0.3 < Q{sup 2} < 10{sup 4} GeV{sup 2} and 2.10{sup -4} < x < 1. The steep rise of the structure function F{sub 2} with x decreasing is observed at x values below 10{sup -1} and up to Q{sup 2} values of about 1000 GeV{sup 2}. The interpretation of the F{sub 2} behaviour at low x by the BFKL and GLAP mechanisms is discussed together with possible ``footprints`` of the BFKL dynamics in the hadronic final states of deep inelastic scattering events at HERA. The properties of the deep inelastic scattering events at HERA with no energy in a large gap of rapidity close to the proton direction are reviewed. A signal from rapidity gap events in CDF and DO experiments is presented. (author). 102 refs., 31 figs., 5 tabs.
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.
International Nuclear Information System (INIS)
The double differential cross sections are measured as a function of the mass number and total kinetic energy for products of the 40Ar (220 MeV)+124Sn, 40Ar(220 MeV)+108Ag, 40Ar(220 MeV)+139La and 64Zn (315 MeV)+122Sn, 64Zn(315 MeV)+108Ag, 64Zn (315 MeV)+139La reactions. The effect of specific features of the shell structure of colliding nuclei on the maximum position of the fragment mass distribution is studied within the microscopic approach. A qualitative difference in dependences of the maximum position on the total kinetic energy of products of the reactions with 64Zn and 40Ar observed experimentally points to the shell structure of interacting nuclei
Nuclear structure functions at low- $x$ in a holographic approach
Agozzino, LucaDipartimento di Fisica, Universitá di Catania, via S. Sofia 62, 95125 , Catania, Italy; Castorina, Paolo; Colangelo, Pietro
2014-01-01
Nuclear effects in deep inelastic scattering at low x are phenomenologically described changing the typical dynamical and/or kinematical scales characterizing the free nucleon case. In a holographic approach, this rescaling is an analytical property of the computed structure function F2(x,Q2) . This function is given by the sum of a conformal term and of a contribution due to quark confinement, depending on IR hard-wall parameter z0 and on the mean square distances, related to a parameter Q? ...
Quark-parton model for the structure function W2 of the proton and neutron in their rest systems
International Nuclear Information System (INIS)
The deep-inelastic structure function W2 is calculated using the impulse approximation for mass-shell partons in the target-nucleon rest system. Bjorken scaling and the approach to scaling are shown to follow from parton kinematics in the rest system. The partons are identified as quarks and a simple harmonic-oscillator quark model is used to fit the proton and neutron structure functions down to x approx. 0.1. The neutron structure function requires an inherently non-SU(6) quark model based on relative coordinates that we argue should replace shell-model SU(6) quark models that have been used extensively
The relativistic Lagrangian: Nucleon-nucleon potential
Sahu, B. B.; Singh, S. K.; Bhuyan, M.; Patra, S. K.
2013-04-01
The microscopic origin of nucleon-nucleon (NN) potential is introduced as an alternative to the popular M3Y form for the first time using the relativistic mean field (RMF) theory with the non linear terms in ?-meson. Its applicability is examined with the study of cluster radioactivity by folding it with the RMF-densities of cluster and daughter nuclei to obtain the optical potential in the region of nuclides just above the double magic core 100Sn. The results obtained found comparable with the widely used M3Y NN interactions.
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
Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order
Epelbaum, E; MeiÃŸner, 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...
Evaluation of charged current neutrino-nucleon interaction differential cross section
International Nuclear Information System (INIS)
The charged current neutrino-nucleon interaction differential cross section are evaluated in the kinematical range using QCD inspired Thermodynamic Bag Model (TBM). We also discuss the x and Q2 dependence of nucleon structure functions F2(x,Q2) and xF3(x,Q2) estimated with statistical approach. The contribution of strange quark distribution function to the cross section is explored and the results obtained have been compared with relevant data from NuTeV and CHORUS experiments.
Evaluation of charged current neutrino-nucleon interaction differential cross section
Energy Technology Data Exchange (ETDEWEB)
Ganesamurthy, Kuppusamy, E-mail: udckgm@sify.com [Department of Physics, Urumu Dhanalakshmi College, Tiruchirapalli 620 019 (India); Hariharan, Chellamuthu, E-mail: chari_lect@yahoo.co.in [Department of Physics, J.J. College of Engineering and Technology, Tiruchirapalli 620 009 (India)
2011-06-01
The charged current neutrino-nucleon interaction differential cross section are evaluated in the kinematical range using QCD inspired Thermodynamic Bag Model (TBM). We also discuss the x and Q{sup 2} dependence of nucleon structure functions F{sub 2}(x,Q{sup 2}) and xF{sub 3}(x,Q{sup 2}) estimated with statistical approach. The contribution of strange quark distribution function to the cross section is explored and the results obtained have been compared with relevant data from NuTeV and CHORUS experiments.
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.
Entropy behavior with nucleon-antinucleon asymmetry
Energy Technology Data Exchange (ETDEWEB)
Silva, J.B.; Delfino, A.; Malheiro, M. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica]. E-mail: jbsilva@if.uff.br
2003-07-01
The recent STAR Collaborations at RHIC found anti-proton-to-proton ratio about 0.6. Constraining the baryonic density to satisfy this experiment data, a set of hadronic models is studied to investigate the baryonic entropy per particle behaviour. We also investigate the baryonic chemical potential as a function of the anti-nucleon-nucleon ratio. Our results show a systematic increasing (decreasing) of the entropy per particle (baryonic chemical potential) as this ratio increases. (author)
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.
Chiral extrapolations for nucleon electric charge radii
Hall, J. M. M.; Leinweber, D. B.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia)
2013-01-01
Lattice simulations for the electromagnetic form factors of the nucleon yield insights into the internal structure of hadrons. The logarithmic divergence of the charge radius in the chiral limit poses an interesting challenge in achieving reliable predictions from finite-volume lattice simulations. Recent results near the physical pion mass are examined in order to confront the issue of how the chiral regime is approached. The electric charge radius of the nucleon presents a...
PUFAs: Structures, Metabolism and Functions.
Wiktorowska-Owczarek, Anna; Berezi?ska, Ma?gorzata; Nowak, Jerzy Z
2015-01-01
Polyunsaturated fatty acids (PUFAs) include two series of fatty acids: omega-6 and omega-3 series. PUFAs have amphiphatic properties: hydrophilic head and hydrophobic tail. Such structure and other properties of unsaturated fatty acids are responsible for exerting the following biological action: maintaining cell-membrane fluidity, inhib- iting inflammatory processes, decreasing secretion of proinflammatory cytokines by monocytes/macrophages, decreasing susceptibility to ventricular rhythm disorders of the heart, improving functions of vascular endothe- lial cells, inhibiting blood platelet aggregation and decreasing triglyceride synthesis in the liver. In an organism, aracidonic acid (ARA) is converted to prostanoids series 2 (PGE2, PGI2, TXA2) and leukotrienes series 4 (LTB4, LTC4, LTD4) which are endowed with pro-inflammatory potential and are able to induce platelet aggregation and vasoconstriction. The metabolism of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) gives prostanoids series 3 (PGE3, PGI3, TXA3) and leukotrienes series 5 (LTB5, LTC5, LTD5); this group of eicosanoids shows anti-inflammatory, antiplatelet and antiarrhythmic properties. PMID:26771963
Off-shell properties of the Paris nucleon-nucleon potential and implications for few-body systems
International Nuclear Information System (INIS)
We investigate the half-off-shell properties for the Paris nucleon-nucleon potential and for a separable representation of it. Deuteron bound-state and scattering wave functions as well as Noyes-Kowalski functions are considered. Essential features with respect to elastic electron-deuteron and nucleon-deuteron scattering are discussed. We find that some polarization observables of these processes dismiss certain off-shell behaviours encountered, for instance, in various phenomenological separable potentials
Nuclear shell model calculations with fundamental nucleon-nucleon interactions
Pan, X W; Vallières, M
1995-01-01
Some fundamental Nucleon-Nucleon interactions and their applications to finite nuclei are reviewed. Results for the few-body systems and from Shell-Model calculations are discussed and compared to point out the advantages and disadvantages of the different Nucleon-Nucleon interactions. The recently developed Drexel University Shell Model (DUSM) code is mentioned.
What do we learn from polarization measurements in deep-inelastic electron-nucleon scattering
International Nuclear Information System (INIS)
We examine what can be learned from deep-inelastic electron-nucleon scattering with polarized initial electrons and measurement of the polarization of the final electrons. A direct evaluation of the separate structure functions W1 and W2 is shown to be possible
The spin of the nucleon in deep inelastic lepton scattering experiments
Energy Technology Data Exchange (ETDEWEB)
Mallot, G.K. [European Organization for Nuclear Research, Geneva (Switzerland). PPE Div.]|[Mainz Univ. (Germany). Inst. fuer Kernphysik
1992-09-01
The current experimental status of the spin dependent structure functions as measured in polarized deep inelastic scattering of charged leptons from nucleons is reviewed. The proposals for new experiments at CERN, SLAC and HERA are discussed with special emphasis on the experiment of the Spin Muon collaboration at CERN which has started data taking.
The spin of the nucleon in deep inelastic lepton scattering experiments
Energy Technology Data Exchange (ETDEWEB)
Mallot, G.K. (European Organization for Nuclear Research, Geneva (Switzerland). PPE Div. Mainz Univ. (Germany). Inst. fuer Kernphysik)
1992-01-01
The current experimental status of the spin dependent structure functions as measured in polarized deep inelastic scattering of charged leptons from nucleons is reviewed. The proposals for new experiments at CERN, SLAC and HERA are discussed with special emphasis on the experiment of the Spin Muon collaboration at CERN which has started data taking.
Neutral-current x-distributions in the neutrino-nucleon scattering
International Nuclear Information System (INIS)
In this thesis the measurement of the x distribution of the structure functions for deep inelastic charged-current and neutral-current neutrino-nucleon interactions at the CERN 200 GeV narrow-band neutrino beam is described. (HSI)
The E142 SLAC experiment: measurement of the neutron gn1(x) spin structure function
International Nuclear Information System (INIS)
This thesis describes the E142 experiment which has been carried out at the Stanford Linear Accelerator (SLAC), USA, from October to December 1992. This experiment of polarized inelastic scattering of a 22.6 GeV electron beam on a polarized helium 3 target has allowed the first measurement of the neutron gn1(x) spin structure function. The knowledge of this structure function gives informations on the nucleon spin structure. On the other hand, the gn1(x) structure function integral value on the 02 mean value of 2 GeV2 after some extrapolations. This value is at about two standard deviations away from the theoretical predictions of the Ellis-Jaffe rule. Thanks to the existing experimental results for the proton (E143 experiment), the Bjorken sum rule has been precisely tested and is perfectly compatible with the theoretical value. The results have allowed to estimate the nucleon spin fraction carried by the quarks. (J.S.). 86 refs., 58 figs., 13 tabs
Cottingham formula and nucleon polarisabilities
Gasser, J.; Hoferichter, M.; Leutwyler, H.; Rusetsky, A.
2015-08-01
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections - provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon 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.
Cottingham formula and nucleon polarizabilities
Gasser, J; Leutwyler, H; Rusetsky, A
2015-01-01
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections---provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon polarizabilities. We evaluate the sum rule for the difference between the electric polarizabilities of proton and neutron by means of the available parameterizations of the data and compare the result with experiment.
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.)
Radical Conservatism And Nucleon Decay
Wilczek, Frank
2000-01-01
Unification of couplings, observation of neutrino masses in the expectedrange, and several other considerations confirm central implications ofstraightforward gauge unification based on SO(10) or a close relative andincorporating low-energy supersymmetry. The remaining outstanding consequenceof this circle of ideas, yet to be observed, is nucleon instability. Clearly,we should aspire to be as specific as possible regarding the rate and form ofsuch instability. I argue that not only esthetics, but also the observedprecision of unification of couplings, favors an economical symmetry-breaking(Higgs) structure. Assuming this, one can exploit its constraints to buildreasonably economical, overconstrained yet phenomenologically viable models ofquark and lepton masses. Putting it all together, one arrives at reasonablyconcrete, hopeful expectations regarding nucleon decay. These expectations areneither ruled out by existing experiments, nor hopelessly inaccessible.
From skyrmions to the nucleon-nucleon potential
International Nuclear Information System (INIS)
The large NC limit implies that nucleons are topological solitons of an effective meson field theory. When deriving the nucleon-nucleon potential in such a picture one has to deal with interacting solitons. Numerical simulations of soliton collisions are presented. At low kinetic energy the complexity of such events is reduced and an adiabatic treatment becomes possible. Semiclassical quantization within the Born-Oppenheimer Approximation yields a potential which shows the basic features of empirical nucleon-nucleon interaction. (orig.)
Nucleon transfer at the example of the 13C(13C,12C)14C reactions
International Nuclear Information System (INIS)
On the basis of molecular wave functions a theory of nucleon-transfer in heavy ion reactions is presented. The particle-core-model for a system of two cores and N- valence nucleons is applied by using two-center shell model (TCSM) wavefunctions for the extra particles and describing to collectively excitable cores by rotator- vibrator models. Potentials for shape polarization are contained in the two-center shell model and in the interaction between the cores. The transfer (and excitation) of the valence particles is caused by the radial and rotational couplings. Using the same TCSM in all fragmentations, numerical calculations are made for the real neutron transfer reaction 13C (13C, 12C) 14C. The excitation function shows prominent structures as seen in experiment but not produced in a single-step (DWBA-) treatment. Therefore, the nucleon transfer in this system relies on a molecular orbital mechanism. (orig.)
Universality in low energy states: from few-atoms to few-nucleons
Kievsky, A
2013-01-01
We investigate universal behavior in elastic atom-dimer scattering below the dimer breakup threshold calculating the atom-dimer effective-range function $ak\\cot\\delta$. We compare our results with the universal zero-range form deduced by Efimov, $ak\\cot\\delta=c_1(ka)+c_2(ka)\\cot[s_0\\ln(a\\kappa_*)+\\phi(ka)]$, for different values of the two-body scattering length $a$ and of the three-body parameter $\\kappa_*$. We observe a good agreement introducing a particular type of finite-range corrections. Furthermore, we show that the same parameterization describes a very different system: nucleon-deuteron scattering below the deuteron breakup threshold. Our analysis reveals a universal behavior that ranges from few-atom systems to few-nucleon systems, and clarifies the nature of the pole structure in the effective-range function of nucleon-deuteron scattering.
Clustering effect of nucleonic matter in low-density region
International Nuclear Information System (INIS)
Full text: We consider clustering effect of symmetric and asymmetric nucleonic matter in low-density situation. To describe such a system, we adopt a Bloch function (B.F.) as a single-particle state. When clusters form and the matter has a periodic structure, a nucleon feels a periodic mean field. In analogy with electrons in a crystal, such a single-particle state of a nucleon is described by linear combination of atomic orbitals, ? ? ? from i=1 until A ?cki (ri) Xi (?i, ?i), ?ck (r) = (a/L)3/2 (1/Nck)3/2 ? eikma ?c (r-ma), where ?ck and Xi are the spatial and spin-isospin part of a single-particle wave function, respectively, and ?c is an atomic orbital. a is the periodic distance, L3 is the normalization volume, and Nck is the normalization factor. In the case of an alpha-particle-like density fluctuation in symmetric nucleonic matter, we adopt the s-wave function as ?c, ?s(r) = (b/ ? ?)3/2 exp [-b2/2 r2], For the purpose of describing asymmetric nucleonic matter, we have to prepare a B.F. constructed by a p-wave function, ?px (r) = (b/? ?)3/2 ? 2 bx exp [-b2/2 r2], but such a p-wave B.F. is not orthogonal to a s-wave B.F. Here we define the orthogonal p-wave B.F. to the s-wave B.F. as follows: ?opx,k (r) = (1/Nopk)1/2 [?pxk (r) - [?sk/?pxk] ?sk (r)], ?opyk and ?opxk are also defined in the similar way. It should be noticed that these orthogonal p-wave B.F. are not only orthogonal to the s-wave B.F. but also orthogonal among them. By the use of such B.F s. we can describe both completely clusterized matter in one limit and uniform matter in another limit, and also in-medium states. In this report we discuss clustering phenomena of both symmetric and asymmetric nucleonic matter under low-density situation. (Author)
International Nuclear Information System (INIS)
The asymptotic normalization constants (ANC) C0 and C2 of the triton have been calculated by the hyperspherical harmonics expansion method with the Reid soft core potential (no three body force). The results do not agree with the corresponding calculations by the Faddeev method, when only a few hyperspherical partial waves are included. However Schneider's convergence theorems on hyperspherical expansion allow one to extrapolate the results for a large number of partial waves and then they agree fairly well with the Faddeev results. This indicates that even though the hyperspherical expansion for the asymptotic wave function is very slow, a convergent and reliable wave function is attained by extrapolation of a relatively small-sized calculation
Carbone, Arianna; Rios, Arnau; Polls, Artur
2013-01-01
We present calculations for symmetric nuclear matter using chiral nuclear interactions within the Self-Consistent Green's Functions approach in the ladder approximation. Three-body forces are included via effective one-body and two-body interactions, computed from an uncorrelated average over a third particle. We discuss the effect of the three-body forces on the total energy, computed with an extended Galitskii-Migdal-Koltun sum-rule, as well as on single-particle propertie...
Effective constraint algebras with structure functions
Bojowald, Martin; Brahma, Suddhasattwa
2014-01-01
This article presents the result that fluctuations and higher moments of a state do not imply quantum corrections in structure functions of constrained systems. Consequences for canonical quantum gravity, whose structure functions encode space-time structure, are discussed. In particular, deformed algebras found in models of loop quantum gravity provide reliable information even in the Planck regime.
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.
International Nuclear Information System (INIS)
The behavior of a nucleon in nuclear medium is discussed in Chiral Color Dielectric Model. It is assumed that the nucleons in nuclear medium produces a background dielectric field and the quark and dielectric field equations are solved self consistently in presence of the dielectric field. A nucleon in nuclear medium is then constructed by means of standard procedure followed in chiral bag models. The corrections due to center of mass motion, color magnetic interaction and meson interaction are included. The calculations show that the nucleon becomes bigger in the medium but its mass does not change much. It is found that beyond a certain density, bound solutions in which quarks are bound in self-generated dielectric field are not possible. Thus, the calculations indicate that there is a critical density beyond which the matter consists of deconfined quarks. (author)
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)
Pita, S
2000-09-01
The structure of the neutron rich light nuclei {sup 11}Be and {sup 10}Li has been investigated by means of one nucleon transfer reactions. The experiments have been carried out at GANIL in inverse kinematics using {sup 11}Be secondary beams. The {sup 11}Be(p,d){sup 10}Be reaction bas been studied at 35.3 MeV/u. The {sup 10}Be ejectiles were analyzed by the spectrometer SPEG, and coincident deuterons were detected in the position sensitive silicon detector CHARISSA. Transfer cross sections to 0{sup +}{sub 1} and 2{sup +}{sub 1}, states in {sup 10}Be were measured up to {theta}{sub CM} = 16 deg. and compared to DWBA and CRC predictions. The effects of neutron-cure couplings on reaction form factors have been studied by solving coupled equations in the framework of a vibrational model. It is shown that the rate of core excitation {sup 10}Be{sub 2+} in the {sup 11}Be{sub gs} wave function is overestimated by a standard analysis with form factors given by the usual Separation Energy prescription. The former model predicts a rate of core excitation of 16% and leads to theoretical cross sections which are in good agreement with the experimental data. The aim of the {sup 11}Be(d,{sup 3}He){sup 10}Li experiment, realized at 37 MeV/u, was to measure the distribution of the 2s neutron strength in the unbound nucleus {sup 10}Li. The energy spectrum was deduced from the {sup 3}He energy and angle measured by the silicon strip detector array MUST. An asymmetric peak is clearly observed near the threshold, with a maximum at -S{sub n} = 130 keV. This constitutes a direct proof of the inversion of 2s and 1p{sub 1/2} shells in {sup 10}Li, which was until now a controversial question in spite of many experimental efforts. On the other band the analysis of the {sup 11}Be(d,t){sup 10}Be reaction studied in the same experiment confirms the results obtained in the {sup 11}Be(p,d){sup 10}Be reaction concerning the {sup 11}Be{sub gs} structure. This work shows the interest and feasibility of studies of the shell properties of exotic nuclei using transfer reactions induced by radioactive beams and constitutes the beginning of a program devoted to this kind of experiment. (author)
Functional keratin as structural platforms
Wool with up to 95% keratin by weight is a rich and pure source of proteinous biomaterial. As polymeric polyamide it exhibits high functionality through amide, carboxyl, sulfoxide, sulfide, and thiosulfide functions. Solubilized wool was transformed into keratin morphologies with the unique characte...
Measurement of the deuteron elastic structure functions at large momentum transfers
Energy Technology Data Exchange (ETDEWEB)
Kathy McCormick
1999-08-01
The cross section for elastic electron-deuteron scattering has been measured using the Hall A Facility of Jefferson Laboratory. Scattered electrons and recoiling deuterons were detected in coincidence in the two 4 GeV/c High Resolution Spectrometers (HRS) of Hall A. The deuteron elastic structure functions A(Q{sup 2}) and B(Q{sup 2}) have been extracted from these data. Results for the measurement of A(Q{sup 2}) in the range of 0.7 â‰¤ Q{sup 2} â‰¤ 6.0 (GeV/c){sup 2} are reported. Results for the magnetic structure function, B(Q{sup 2}), are presented in the range of 0.7 â‰¤ Q{sup 2} â‰¤ 1.35 (GeV/c){sup 2}. The results for both structure functions are compared to predictions of meson-nucleon based models, both with and without the inclusion of meson-exchange currents. The A(Q{sup 2}) results are compared to predictions of the dimensional scaling quark model and perturbative quantum chromodynamics. The results can provide insights into the transition from meson-nucleon to quark-gluon descriptions of the nuclear two-body system.
Chiral Odd Structure Functions in The Nambu--Jona--Lasinio Soliton Model
Gamberg, Leonard; Reinhardt, Hugo; Weigel, Herbert
1998-10-01
We study unpolarized and polarized nucleon structure functions(H. Weigel, L. Gamberg, and H. Reinhardt, Mod. Phys. Lett. A11) (1996) 3021; Phys. Lett. B399 (1997) 287;Phys. Rev. D55(1997) 6910. within the bosonized Nambu--Jona--Lasinio (NJL) model where the nucleon emerges as a chiral soliton(R. Alkofer, H. Reinhardt and H. Weigel, Phys. Rep. 265) (1996) 139.. These considerations attempt to merge the parton model description of deep inelastic scattering with the phenomenologically successful picture of baryons as chiral solitons. In addition we report on the calculation of the chiral odd quark distributions(L. Gamberg, H. Reinhardt and H. Weigel, "Chiral odd structure functions from a chiral soliton", hep-ph/9801379, Phys. Rev. D. in press.) and the corresponding structure functions h_T(x,Q^2) and h_L(x,Q^2). At the low model scale, Q_0^2, we find that the leading twist effective quark distributions, f_1^(q)(x,Q_0^2), g_1^(q)(x,Q_0^2) and h_T^(q)(x,Q_0^2) satisfy Soffer's inequality for both quark flavors q=u,d. The Q^2 evolution of the twist--2 contributions is performed according to the standard GLAP formalism while the twist--three pieces, \\overlineg_2(x) and \\overlineh_L(x), are evolved according to the large NC scheme.
Carbone, Arianna; Polls, Artur
2013-01-01
We present calculations for symmetric nuclear matter using chiral nuclear interactions within the Self-Consistent Green's Functions approach in the ladder approximation. Three-body forces are included via effective one-body and two-body interactions, computed from an uncorrelated average over a third particle. We discuss the effect of the three-body forces on the total energy, computed with an extended Galitskii-Migdal-Koltun sum-rule, as well as on single-particle properties. Saturation properties are substantially improved when three-body forces are included, but there is still some underlying dependence on the renormalization scale.
International Nuclear Information System (INIS)
Data from an exposure of the BEBC bubble chamber filled with deuterium to neutrino and antineutrino wide band beams have been used to extract the x dependence of the structure functions for scattering on protons and neutrons and the fractional momentum distributions of the valence quarks and the antiquarks of different flavours. The difference F2sup(n) - F2sup(p) is compared with recent data from high energy ?D scattering. A result is also obtained on the sum rule giving the difference between the number of up and down quarks in the nucleon. (orig.)
Measurement of the neutron F2 structure function via spectator tagging with CLAS
Baillie, N.; S. Tkachenko; Christy, M. E.(Hampton University, 23668, Hampton, VA, USA); Fenker, H.; Griffioen, K.A.; Kuhn, S. E.; Melnitchouk, W.; Tvaskis, V; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Amaryan, M. J.; Briscoe, W. J.; Brooks, W. K.; Carman, D. S.
2011-01-01
We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to < 100 MeV and their angles to < 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance a...
Measurements of the proton and deuteron spin structure function g$_{2}$ and asymmetry A$_{2}$
Abe, K; Anthony, P L; Antonov, R D; Arnold, R G; Averett, T; Band, H R; Bauer, J M; Borel, H; Bosted, P E; Breton, V; Button-Shafer, J; Chen, J P; Chupp, T E; Clendenin, J E; Comptour, C; Coulter, K P; Court, G R; Crabb, D; Daoudi, M; Day, D; Dietrich, F S; Dunne, J; Dutz, H; Erbacher, R D; Fellbaum, J; Feltham, A; Fonvieille, H; Frlez, E; Garvey, D; Gearhart, R A; Gómez, J; Grenier, P; Griffioen, K A; Høibraten, S; Hughes, E W; Hyde-Wright, C E; Johnson, J R; Kawall, D; Klein, A; Kuhn, S E; Kuriki, M; Lindgren, R; Liu, T; Lombard-Nelsen, R M; Marroncle, J; Maruyama, T; Maruyama, X K; McCarthy, J; Meyer, W T; Meziani, Z E; Minehart, R C; Mitchell, J; Morgenstern, J; Petratos, G G; Pitthan, R; Pocanic, D; Prescott, C; Prepost, R; Raines, P; Raue, B A; Reyna, D; Rijllart, A; Roblin, Y; Rochester, L S; Rock, S E; Rondon-Aramayo, O A; Sick, I; Smith, L C; Smith, T B; Spengos, M; Staley, F; Steiner, P; Saint-Lorant, S J; Stuart, L M; Suekane, F; Szalata, Z M; Tang, H; Terrien, Y; Usher, T; Walz, D; White, J L; Witte, K; Young, C C; Youngman, B; Yuta, H; Zapalac, G H; Zihlmann, B; Zimmerman, D
1996-01-01
We have measured proton and deuteron virtual photon-nucleon asymmetries A2p and A2d and structure functions g2p and g2d over the range 0.03
Target mass corrections for spin-dependent structure functions in collinear factorization
Accardi, A.; Melnitchouk, W.
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.
Functional Dynamics; 2, Syntactic Structure
Kataoka, N
1999-01-01
Functional dynamics, introduced in a previous paper, is analyzed, focusing on the formation of a hierarchical rule to determine the dynamics of the functional value. To study the periodic (or non-fixed) solution, the functional dynamics is separated into fixed and non-fixed parts. It is shown that the fixed parts generate a 1-dimensional map by which the dynamics of the functional values of some other parts are determined. Piecewise-linear maps with multiple branches are generally created, while an arbitrary one-dimensional map can be embedded into this functional dynamics if the initial function coincides with the identity function over a finite interval. Next, the dynamics determined by the one-dimensional map can again generate a `meta-map', which determines the dynamics of the generated map. This hierarchy of meta-rules can continue recursively. It is also shown that the dynamics can produce `meta-chaos' with an orbital instability that is stronger than exponential. The relevance of the generated hierarch...
Moments of the virtual photon structure function
International Nuclear Information System (INIS)
The photon structure function is a useful testing ground for QCD. It is perturbatively computable apart from a contribution from what is usually called the hadronic component of the photon. There have been many proposals concerning this nonperturbative part of the real photon structure function. By studying moments of the virtual photon structure function, we explore the extent to which proposed nonperturbative contributions can be identified experimentally. (orig.)
Progress on nuclear modifications of structure functions
Kumano, S.(KEK Theory Center, Institute of Particle and Nuclear Studies, KEK, 1-1, OHO, 305-0801, Tsukuba, Ibaraki, Japan)
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 he...
Recent results on nucleon sigma terms in lattice QCD
International Nuclear Information System (INIS)
It has proven a significant challenge to experiment and phenomenology to extract a precise values of the nucleon sigma terms. This difficulty opens the window for lattice QCD simulations to lead the field in resolving this aspect of nucleon structure. Here we report on recent advances in the extraction of nucleon sigma terms in lattice QCD. In particular, the strangeness component is now being resolved to a precision that far surpasses best phenomenological estimates.
Nuclear effects in the structure functions
Indian Academy of Sciences (India)
E Marco; E Oset; S K Singh
2003-11-01
By using a relativistic framework and accurate nuclear spectral function the structure functions $F_{2A}$ and $F_{3A}$ of deep inelastic charged lepton and neutrino scattering are calculated in nuclei and results are presented.
Polarized quark distributions in bound nucleon and polarized EMC effect in Thermodynamical Bag Model
Energy Technology Data Exchange (ETDEWEB)
Ganesamurthy, Kuppusamy, E-mail: udckgm@sify.co [Research Department of Physics, Urumu Dhanalakshmi College, Trichy 620019 (India); Sambasivam, Raghavan, E-mail: udcsam@sify.co [Research Department of Physics, Urumu Dhanalakshmi College, Trichy 620019 (India)
2011-04-15
The polarized parton distribution functions (PDFs) and nuclear structure functions are evaluated by the phenomenological Thermodynamical Bag Model for nuclear media {sup 7}Li and {sup 27}Al. The Fermi statistical distribution function which includes the spin degree of freedom is used in this statistical model. We predict a sizeable polarized EMC effect. The results of quark spin sum and axial coupling constant of bound nucleons are compared with theoretical predictions of modified Nambu-Jona-Lasinio (NJL) model by Bentz et al.
Exclusive experiments on few nucleon systems at Saclay
International Nuclear Information System (INIS)
The transverse and longitudinal responses for the 4He(e,e'p)3H reaction have been separated in the low missing momentum region. The transverse spectral function agrees with theory whereas the longitudinal spectral function is low by 30%. The 4He(e,e'p)X reaction was studied at high missing momenta. The continuum cross-section (X = 2H,n and X = pnn) dominates over the two-body break-up (X = 3H) for pm > 300 MeV/c. Moreover, this continuum cross-section has a characteristic structure that reveals an effect of short-range correlation between two nucleons
Nucleon-nucleon interaction and large Nc QCD
International Nuclear Information System (INIS)
The nature of the nonrelativistic nucleon-nucleon potential in the large-Nc limit is discussed. In particular, we address the consistency of the meson-exchange picture of nucleon interactions. It is shown that the nonrelativistic nucleon-nucleon potential extracted from the Feynmann graphs up to and including two-meson-exchange diagrams satisfies the spin-flavor counting rules of Kaplan and Savage and of Kaplan and Manohar, provided the nucleon momenta is of order Nc0. The key to this is a cancellation of the retardation effect of the box graphs against the contributions of the crossed-box diagram. The consistency requires including ? as an intermediate state
Functional domain structure of fibronectin.
Sekiguchi, K; Hakomori, S.
1980-01-01
Structural domains of fibronectin (FN) and their ability to associate with cell surface components have been systematically investigated. Plasma FN was cleaved into three structural domains (Mr 150,000-140,000, 40,000, and 32,000) by sequential digestion with trypsin and thermolysin. A single digestion with thermolysin alone generated Mr 150,000-140,000, 40,000, and smaller fragments. With the inclusion of thermolysin, but not with other proteases, one can, with a high yield dissect FN simult...
Test of the Bonn nucleon-nucleon potential in nucleon-antinucleon scattering
International Nuclear Information System (INIS)
Results obtained in an investigation of the G-parity transformed Bonn NN-potential which is merged with a previously developed quark-gluon annihilation potential are discussed. Comparison with data for elastic and charge exchange reactions at the same energy allows for studying complementary sets of helicity amplitudes which are dominated by specific meson exchanges. Assumptions about meson-nucleon form factors can now be tested that way. On the other hand forward structures in differential cross sections are sensitive to both the annihilation strength and range. The analysis of precise proton-antiproton ? proton-antiproton and nucleon-antinucleon data from K.E.K. and L.E.A.R. allows for constraints on the quark core rise of the nucleon; the Bonn potential (which is given in momentum space) when combined with the quark-gluon annihilation potential seems to be much less sensitive to variations of the quark core radius than other models (which are given in r-space). (author). 14 figs., 26 refs
Toward a “structural BLAST”: Using structural relationships to infer function
Dey, Fabian; Cliff Zhang, Qiangfeng; Petrey, Donald; Honig, Barry
2013-01-01
We outline a set of strategies to infer protein function from structure. The overall approach depends on extensive use of homology modeling, the exploitation of a wide range of global and local geometric relationships between protein structures and the use of machine learning techniques. The combination of modeling with broad searches of protein structure space defines a “structural BLAST” approach to infer function with high genomic coverage. Applications are described to the prediction of p...
Bound nucleon dynamics in relativistic mean field theory and quasi-elastic electron scattering
International Nuclear Information System (INIS)
We compare results obtained with relativistic and non-relativistic bound nucleon wave functions on differential cross sections for electron induced one nucleon knock-out at quasi-elastic kinematics. We discuss the role of the negative-energy component of the relativistic bound nucleon wave functions and the issue of factorization of the differential cross section. (authors)
Low-momentum interaction in few-nucleon systems
International Nuclear Information System (INIS)
The low-momentum nucleon-nucleon interaction Vlowk is applied to three- and four-nucleon systems. We investigate the 3H, 3He, and 4He binding energies for a wide range of the momentum cutoffs. By construction, all low-energy two-body observables are cutoff independent, and therefore, any cutoff dependence is due to missing three-body or higher-body forces. We argue that for reasonable cutoffs Vlowk is similar to high-order interactions derived from chiral effective field theory. This motivates augmenting Vlowk by corresponding three-nucleon forces. The set of low-momentum two- and three-nucleon forces can be used in calculations of nuclear structure and reactions. We find that three-nucleon force contributions are perturbative for small cutoffs
Brazilian relativistic O(q4) two-pion exchange nucleon-nucleon potential: parametrized version
International Nuclear Information System (INIS)
In our recent works we derived a chiral O(q4) two-pion exchange nucleon-nucleon potential (TPEP) formulated in a relativistic baryon (RB) framework, expressed in terms of the so called low energy constants (LECs) and functions representing covariant loop integrations. In order to facilitate the use of the potential in nuclear applications, we present a parametrized version of our configuration space TPEP. (author)
Brazilian relativistic O(q**4) two-pion exchange nucleon nucleon potential: Parametrized version
Energy Technology Data Exchange (ETDEWEB)
C.A. da Rocha; R. Higa; M.R. Robilotta
2007-03-01
In our recent works we derived a chiral O(q4) two-pion exchange nucleon-nucleon potential (TPEP) formulated in a relativistic baryon (RB) framework, expressed in terms of the so called low energy constants (LECs) and functions representing covariant loop integrations. In order to facilitate the use of the potential in nuclear applications, we present a parametrized version of our configuration space TPEP.
Nucleon mean-free path in the medium
Somà V.; Rios A
2014-01-01
A microscopic determination of the mean-free path of a nucleon in symmetric nuclear matter is presented. Calculations are based on self-consistent Green’s functions theory within the ladder approximation and use dierent realistic nucleon-nucleon potentials supplemented by semi-phenomenological three-body forces. Temperature and density dependence are discussed. At zero temperature and nuclear saturation density we find that, for energies above 50 MeV, a nucleon has a mean-free path of 4 to...
Predicting protein structure classes from function predictions
DEFF Research Database (Denmark)
Sommer, I.; Rahnenfuhrer, J.; de Lichtenberg, Ulrik; Lengauer, T.
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....