Nucleon structure functions in noncommutative space-time
Rafiei, Ali; Mirjalili, Abolfazl
2016-01-01
In the context of noncommutative space-time, we investigate the nucleon structure functions which plays an important role to identify the internal structure of nucleons. We use the corrected vertices and employ new vertices that appear in two approaches of noncommutativity and calculate the proton structure functions in terms of noncommutative tensor \\theta_{\\mu\
A no extensive statistical model for the nucleon structure function
Trevisan, Luis A.; Mirez, Carlos
2013-03-01
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.
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.
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.
Nucleon effective mass and the A dependence of structure functions
Energy Technology Data Exchange (ETDEWEB)
Garcia Canal, C.A.; Santangelo, E.M.; Vucetich, H.
1984-10-08
The nucleon effective mass was successfully used, as the only free parameter, to adjust the ratio R(A) of structure functions measured in a nucleus of mass number A and in the deuteron, for each A value in the SLAC set of experimental data. The resulting A dependence of the effective mass, being linear in A/sup -1/3/, is consistent with the behavior expected from nuclear structure considerations. The extrapolated value of the effective mass for nuclear matter agrees with previous estimations.
Nuclear effects in F_3 structure function of nucleon
Athar, M Sajjad; Vacas, M J Vicente
2007-01-01
We study nuclear effects in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio $R(x,Q^2)=\\frac{F^A_3(x,Q^2)}{AF^N_3(x, Q^2)}$ and the Gross-Llewellyn Smith(GLS) integral $G(x,Q^2)=\\int_x^1 dx F^A_3(x,Q^2)$ in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.
Neutrinos and nucleon structure
Sehgal, L M
1979-01-01
The study of neutrino interactions in matter is yielding a wealth of information on the form factors and structure functions of the nucleon. These data allow tests of models of nucleon structure and of dynamical theories of quarks and gluons. The author attempts a critical appraisal of recent facts and their impact on our theoretical understanding. (35 refs).
Nucleon Structure Function F2 in the Resonance Region and Quark-Hadron Duality
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing; LI Ming-Fei
2003-01-01
Based on a simple nonrelativistic constituent quark model, the nucleon structure function F2 in theresonance region is estimated by taking the contributions from low-lying nucleon resonances into account. Calculatedresults are employed to study quark-hardon duality in the nucleon electron scattering process by comparing them to thescaling behavior from the data in deep inelastic scattering region.
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...
A measurement of the ratio of the nucleon structure function in copper and deuterium
Energy Technology Data Exchange (ETDEWEB)
Ashman, J.; Combley, F.; Salmon, D. (Sheffield Univ. (United Kingdom). Dept. of Physics); Badelek, B.; Ciborowski, J.; Gajewski, J.; Rondio, E.; Ropelewski, L. (Warsaw Univ. (Poland). Inst. of Physics); Baum, G.; Caputo, M.C.; Hughes, V.W.; Oppenheim, R.F.; Papavassiliou, V.; Piegaia, R.; Schueler, K.P. (Yale Univ., New Haven, CT (United States). Dept. of Physics); Beaufays, J.; Jacholkowska, A.; Niinikowski, T.; Osborne, A.M.; Rieubland, J.M. (European Organization for Nuclear Research, Geneva (Switzerland)); Bee, C.P.; Brown, S.C.; Court, G.; Francis, D.; Gabathuler, E.; Gamet, R.; Hayman, P.; Holt, J.R.; Jones, T.; Matthews, M.; Wimpenny, S.J. (Liverpool Univ. (United Kingdom). Dept. of Physics); Benchouk, C.; D' Agostini, G.; Montanet, F.; Pietrzyk, B. (Aix-Marseille-2 Univ., 13 - Marseille (France). Faculte des Sciences de Luminy); Bird, I.G.; Dyce, N.; Sloan, T. (Lancaster Univ. (United Kingdom). Dept. of Physics); Cheung, H.W.K.; Gibson, V.; Gillies, J.; Renton, P.; Taylor; European Muon Collaboration
1993-02-01
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, F[sub 2], 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.).
Nucleon Spin Structure Functions in the Resonance Region and the Duality
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing; FENG Qing-Guo
2003-01-01
We discuss the nucleon spin structure function gl and the difference between the proton and neutrontargets gp1 - gn1 , based on quark model calculation. Quark-hadron duality for the nucleon spin structure function is alsoanalyzed. Effects of the △(1232) and Roper P11(1440) resonances on the spin structure function and on the differencegn1 - gn1 are mentioned. The results of different models for the Roper resonance are also addressed.
Nuclear medium effects in structure functions of nucleon at moderate $Q^2$
Haider, H; Athar, M Sajjad; Singh, S K; Simo, I Ruiz
2015-01-01
Recent experiments performed on inclusive electron scattering from nuclear targets have measured the nucleon electromagnetic structure functions $F_1(x,Q^2)$, $F_2(x,Q^2)$ and $F_L(x,Q^2)$ in $^{12}C$, $^{27}Al$, $^{56}Fe$ and $^{64}Cu$ nuclei. The measurements have been done in the energy region of $1 GeV^2 < W^2 < 4 GeV^2$ and $Q^2$ region of $0.5 GeV^2 < Q^2 < 4.5 GeV^2$. We have calculated nuclear medium effects in these structure functions arising due to the Fermi motion, binding energy, nucleon correlations, mesonic contributions from pion and rho mesons and shadowing effects. The calculations are performed in a local density approximation using relativistic nucleon spectral function which include nucleon correlations. The numerical results are compared with the recent experimental data from JLab and also with some earlier experiments.
Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons
Bodek, A
2015-01-01
We present preliminary results on an experimental study of the nuclear modification of the longitudinal ($\\sigma_L$) and transverse ($\\sigma_T$) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= $\\sigma_L / \\sigma_T$ for nuclei ($R_A$) and for deuterium ($R_D$) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, $R_A< R_D$.
Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons
Energy Technology Data Exchange (ETDEWEB)
Bodek, Arie [Univ. of Rochester, NY (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-08-01
We present preliminary results on an experimental study of the nuclear modification of the longitudinal ($\\sigma_L$) and transverse ($\\sigma_T$) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= $\\sigma_L / \\sigma_T$ for nuclei ($R_A$) and for deuterium ($R_D$) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, $R_A< R_D$.
Statistical Quark Model for the Nucleon Structure Function
Mirez, Carlos; Tomio, Lauro; Trevisan, Luis A.; Frederico, Tobias
2009-06-01
A statistical quark model, with quark energy levels given by a central linear confining potential is used to obtain the light sea-quark asymmetry, d¯/ū, and also for the ratio d/u, inside the nucleon. After adjusting a temperature parameter by the Gottfried sum rule violation, and chemical potentials by the valence up and down quark normalizations, the results are compared with experimental data available.
The polarized structure function of the nucleons with a non-extensive statistical quark model
Trevisan, Luis A.; Mirez, Carlos
2013-05-01
We studied an application of nonextensive thermodynamics to describe the polarized structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution, often used in the statistical models, were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and the chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon and by Δu and Δd of the polarized functions.
Bloom-Gilman Duality of Nucleon Spin Structure Function and Elastic Peak Contribution
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing
2005-01-01
By employing the parametrization form of the nucleon spin structure function in the resonance region,which includes the contributions of the resonance peaks and of nonresonance background, we study Bloom-Gilman quark-hadron duality of g1 both in the inelastic resonance region and elastic one.
Nucleon $g-2$ Structure Function at Large $x$ and Quark-Gluons Correlations
Energy Technology Data Exchange (ETDEWEB)
Zein-Eddine Meziani
2009-12-01
We discuss two recently carried out experiments at Jefferson Lab that measured with precision the spin structure function of the nucleon g2, aiming at the determination of the twist-3 matrix element known as d2 for both the proton and the neutron. This matrix element is related to the average Lorentz color force that a quark experiences just at the instant it is struck. It is also interpreted as a measurement of a linear combination of the electric and magnetic “color polarizability” in the nucleon.
Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons
Energy Technology Data Exchange (ETDEWEB)
Bodek, Arie [University of Rochester, Rochester, NY
2015-09-01
We present preliminary results on an experimental study of the nuclear modification of the longitudinal (σ_{L}) and transverse (σ_{T}) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= σ_{L}/σ_{T} for nuclei (R_{A}) and for deuterium (RD) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, R_{A} < R_{D}.
Nejad, S. Mohammad Moosavi; Khanpour, Hamzeh; Tehrani, S. Atashbar; Mahdavi, Mahdi
2016-10-01
We present a detailed QCD analysis of nucleon structure functions x F3(x ,Q2) , based on Laplace transforms and the Jacobi polynomials approach. The analysis corresponds to the next-to-leading order and next-to-next-to-leading order approximations of perturbative QCD. The Laplace transform technique, as an exact analytical solution, is used for the solution of nonsinglet Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations at low- and large-x values. The extracted results are used as input to obtain the x and Q2 evolution of x F3(x ,Q2) structure functions using the Jacobi polynomials approach. In our work, the values of the typical QCD scale ΛMS¯ (nf) and the strong coupling constant αs(MZ2) are determined for four quark flavors (nf=4 ) as well. A careful estimation of the uncertainties shall be performed using the Hessian method for the valence-quark distributions, originating from the experimental errors. We compare our valence-quark parton distribution functions sets with those of other collaborations, in particular with the CT14, MMHT14, and NNPDF sets, which are contemporary with the present analysis. The obtained results from the analysis are in good agreement with those from the literature.
Spin structure functions of the nucleon at low Q{sup 2} and {nu}
Energy Technology Data Exchange (ETDEWEB)
Burkert, V.D.
1993-06-30
Phenomenological approaches to describe the spin structure functions an spin sum rules for proton and neutrons at low momentum transfer Q{sup 2} and energy transfer {nu}, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A{sub 1}{sup p}, A{sub 2}{sup p} and N{sub 1}{sup n} structure functions at CEBAF in a Q{sup 2} range from 0.15 to 2.0 GeV{sup 2}, and a W range from threshold to 2.2 GeV are presented.
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).
Gold-plated moments of nucleon structure functions in baryon chiral perturbation theory
Lensky, Vadim; Pascalutsa, Vladimir
2014-01-01
We obtain leading- and next-to-leading order predictions of chiral perturbation theory for several prominent moments of nucleon structure functions. These free-parameter free results turn out to be in overall agreement with the available empirical information on all of the considered moments, in the region of low-momentum transfer ($Q^2 < 0.3$ GeV$^2$). Especially surprising is the situation for the $\\delta_{LT}$ moment, which thus far was not reproducible for proton and neutron simultaneously in chiral perturbation theory. This problem, known as the "$\\delta_{LT}$ puzzle," is not seen in the present calculation.
Nucleon structure 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
Energy Technology Data Exchange (ETDEWEB)
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
2002-01-01
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.
Next-to-Leading Order Description of Nucleon Structure Function In Valon Model
Arash, F; Arash, Firooz; Khorramia, Ali Naghi
1999-01-01
We have improved and examined the applicability of the valon model where the structure of any hadron is determined by the structure of its constituent quarks. Nucleon structure functions are calculated within this model in the Next-to-Leading order. The results compare well with the experimental data. The model handles the bound state problem and the calculations show a flat or almost flat behavior for $F_{2}$ which sets in at some region of $x\\leq 10^{-5}$at fixed $Q^{2}$. The emergence of this behavior is a consequence of the model and was not put in a priori as a theoretical guess. It seems that such a flatness can be inferred from HERA data, although, not completely confirmed yet. A set of parton distributions are given and their evolutions are tested. Some qualitative implications of the model for the spin structure of the proton is discussed.
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.
Nuclear effects in F{sub 3} structure function of nucleon
Energy Technology Data Exchange (ETDEWEB)
Athar, M. Sajjad [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India)], E-mail: sajathar@rediffmail.com; Singh, S.K. [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Vacas, M.J. Vicente [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, 46100 Burjassot (Valencia) (Spain)
2008-10-02
We study nuclear effects in the F{sub 3}{sup A}(x) structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio R(x,Q{sup 2})=(F{sub 3}{sup A}(x,Q{sup 2}))/(AF{sub 3}{sup N}(x,Q{sup 2})) and the Gross-Llewellyn Smith (GLS) integral G(x,Q{sup 2})={integral}{sub x}{sup 1}dxF{sub 3}{sup A}(x,Q{sup 2}) in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.
Indian Academy of Sciences (India)
N Barik; R N Mishra
2001-04-01
Considering the nucleon as consisting entirely of its valence quarks conﬁned independently in a scalar-vector harmonic potential; unpolarized structure functions 1(,2) and 2(x,2) are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions (,2) and (,2) are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of 2=0.07 GeV2 to a higher $Q^{2}$ scale of $Q^{2}_{0} = 15$ GeV2 yields (, $Q^{2}_{0}$) and (, $Q^{2}_{0}$) in good agreement with experimental data. The gluon and sea-quark distributions such as (,$Q^{2}_{0}$) and (, $Q^{2}_{0}$) are dynamically generated with a reasonable qualitative agreement with the available data; using the leading order renormalization group equations with appropriate valence-quark distributions as the input.
A detailed study of nucleon structure function in nuclei in the valence quark region
Energy Technology Data Exchange (ETDEWEB)
Bianchi, N. [INFN-Laboratori, Nazionali di Frascati (Italy)
1994-04-01
The so called {open_quotes}EMC effect{close_quotes} discovered during the 1980`s, has caused a big controversy in the community of nuclear and high energy physicists; during the last ten years, five experiments have been performed in different laboratories and several hundreds of papers about the possible interpretation of the modification of the nucleon structure function inside nuclei have been published. However, from the experimental point of view, the main goal of four experiments (EMC, BCDMS, NMC, FNAL) has been to emphasize the region of low x{sub b}, where shadowing effects appear. In the region of valence quarks and nuclear effects (x{sub b} > 0.1 - 0.2) the most reliable data presently available are from the SLAC E139 experiment performed in 1983 with only 80 hours of beam time. New precise data in the valence quark region are necessary to measure separate structure functions F{sub 2}(x{sub b}, Q{sup 2}) and R{sup lt}(x{sub b},Q{sup 2}) = {sigma}{sub l}/{sigma}{sub t}, and to investigate the real A-dependence of the ratio between bound and free-nucleon structure functions which is not completely defined by the SLAC data. Moreover, from the nuclear physics point of view, a measurement on some unexplored nuclei, like {sup 3}He and {sup 48}Ca, would be of great interest. The intermediate scaling region (0.1 < x{sub b} < 0.7) would be accessible at CEBAF if the machine energy will reach 6-8 GeV, as suggested by all the tests performed on the RF cavities. This physics program has been already presented in two letter of intents.
Tests of perturbative QCD using CCFR data for measurements of nucleon structure functions
Energy Technology Data Exchange (ETDEWEB)
Bodek, A.; Budd, H.S.; De Barbaro, P.; Sakumoto, W.K.; Leung, W.C.; Quintas, P.Z.; Sciulli, F.; Arroyo, C.; Bachmann, K.T.; Blair, R.E.; Foudas, C.; King, B.J.; Lefmann, W.C.; Mishra, S.R.; Oltman, E.; Rabinowitz, S.A.; Seligman, W.G.; Shaevitz, M.H.; Merritt, F.S.; Oreglia, M.J.; Schumm, B.A.; Bernstein, R.H.; Borcherding, F.; Fisk, H.E.; Lamm, M.J.; Marsh, W.; Merritt, K.W.B.; Schellman, H.; Yovanovitch, D.D.; Sandler, P.H.; Smith, W.H. (Univ. of Rochester, NY (United States) Columbia Univ., New York, NY (United States) Univ. of Chicago, IL (United States) Fermilab, Batavia, IL (United States) Univ. of Wisconsin, Madison, WI (United States))
1993-04-01
We present measurements of nucleon structure functions, F[sub 2](x, Q[sup 2]) and xF[sub 3](x, Q[sup 2]), from the high-statistics, high-energy neutrino-iron scattering experiment at the Fermilab Tevatron. The existing high-statistics xF[sub 3] determination by the CDHSW collaboration is compared to our data. The data presented here constitute the first corroboration of the QCD prediction of xF[sub 3] evolution at low-x, and yields [Lambda][anti M][anti S] = 210 [+-] 28 [+-] 41 MeV, and a determination of the GLS sum rule at Q[sup 2] = 3 GeV[sup 2], S[sub GLS] = [integral][sup 1][sub x] xF[sub 3]/x dx = 2.50 [+-] 0.018(stat.) [+-]0.078 (syst.). Our value of [Lambda][anti M][anti S] yields [alpha][sub s](M[sub z]) = .111 [+-] .002 [+-] .003 [+-] .003 (scale). Comparison of the neutrino determination of F[sub 2](x, Q[sup 2]) with that obtained from the charged-lepton (e or [mu]) scattering leads to a precise test of the mean-square charge prediction by the Quark Parton Model. The SLAC-CCFR and BCDMS structure function provide a consistent and precise set of structure functions over a large range of Q[sup 2]. (orig.)
Nucleon structure functions and longitudinal spin asymmetries in the chiral quark constituent model
Dahiya, Harleen
2016-01-01
We have analysed the phenomenological dependence of the spin independent ($F_1^{p,n}$ and $F_2^{p,n}$) and the spin dependent ($g_1^{p,n}$) structure functions of the nucleon on the the Bjorken scaling variable $x$ using the unpolarized distribution functions of the quarks $q(x)$ and the polarized distribution functions of the quarks $\\Delta q(x)$ respectively. The chiral constituent quark model ($\\chi$CQM), which is known to provide a satisfactory explanation of the proton spin crisis and related issues in the nonperturbative regime, has been used to compute explicitly the valence and sea quark flavor distribution functions of $p$ and $n$. In light of the improved precision of the world data, the $p$ and $n$ longitudinal spin asymmetries ($A_1^p(x)$ and $A_1^n(x)$) have been calculated. The implication of the presence of the sea quarks has been discussed for ratio of polarized to unpolarized quark distribution functions for up and down quarks in the $p$ and $n$ $\\frac{\\Delta u^p(x)}{u^p(x)}$, $\\frac{\\Delta d...
Polarized structure function sigma_lt' for kaon electroproduction in the nucleon resonance region
Energy Technology Data Exchange (ETDEWEB)
Rakhsha Nasseripour; B. Raue; Daniel Carman; Pawel Ambrozewicz
2008-02-19
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.
Nucleon spin structure II: Spin structure function $g_1^p$ at small $x$
Zhu, Wei
2015-01-01
The spin structure function $g_1^p$ of the proton is studied in a two component framework, where the perturbative evolution of parton distributions and nonperturbative vector meson dominance model are used. We predict the $g_1^p$ asymmetric behavior at small $x$ from lower $Q^2$ to higher $Q^2$. We find that the contribution of the large gluon helicity dominates $g_1^p$ at $x>10^{-3}$ but mixed with nonperturbative component which complicates the asymptomatic behavior of $g_1^p$ at $x<10^{-3}$. The results are compatible with the data including the HERA early estimations and COMPASS new results. The predicted strong $Q^2$- and $x$-dependence of $g_1^p$ at $0.01
Present understanding of the nucleon spin structure
Metz, A
2005-01-01
The present understanding of the spin structure of the nucleon is briefly reviewed. The main focus is on parton helicity distributions, orbital angular momentum of partons as defined through generalized parton distributions, as well as single spin asymmetries and time-reversal odd correlation functions.
Nucleon Parton Structure from Continuum QCD
Bednar, Kyle; Cloet, Ian; Tandy, Peter
2017-01-01
The parton structure of the nucleon is investigated using QCD's Dyson-Schwinger equations (DSEs). This formalism builds in numerous essential features of QCD, for example, the dressing of parton propagators and dynamical formation of non-pointlike di-quark correlations. All needed elements of the approach, including the nucleon wave function solution from a Poincaré covariant Faddeev equation, are encoded in spectral-type representations in the Nakanishi style. This facilitates calculations and the necessary connections between Euclidean and Minkowski metrics. As a first step results for the nucleon quark distribution functions will be presented. The extension to the transverse momentum-dependent parton distributions (TMDs) also be discussed. Supported by NSF Grant No. PHY-1516138.
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.
The nucleon spin structure at short distance
Seidl, Ralf
2008-10-01
The spin structure of the nucleon has been the basis of several surprises in the past. After the EMC experiment showed that the quark spin contribution to the nucleon spin was small, several experiments were performed to further investigate this ``spin crisis.'' Deep inelastic scattering (DIS) experiments at CERN, SLAC, and DESY successfully confirmed the low quark spin contribution to the nucleon. Using semi-inclusive DIS, SMC, HERMES and COMPASS were also able to obtain flavor separated quark polarizations. DIS experiments are only sensitive to gluon polarization at NLO via the QCD evolution of the structure function g1, or through di-jet/hadron production in photon-gluon fusion processes. Proton-proton collisions are sensitive to the gluon polarization at leading order. The RHIC experiments PHENIX and STAR have measured inclusive pion and jet asymmetries which exclude huge gluon polarizations but a substantial contribution to the spin of the nucleon is still possible. Another aspect of spin measurements are transverse spin phenomena. Once deemed to be vanishing in perturbative QCD recent nonzero transverse single spin asymmetries observed at RHIC and HERMES could be explained in the framework of transverse momentum dependent (TMD) distribution and fragmentation functions. One is the so-called Sivers function which requires a nonzero parton orbital angular momentum. Early global analysises were able to combine the data obtained at RHIC, COMPASS and HERMES. Another TMD function is the Collins fragmentation function, first measured at BELLE, which serves as a transverse spin analyzer to extract the quark transverse spin distribution from the SIDIS experiments. Also here a first global analysis of SIDIS and BELLE data has been successfully performed. An overview on recent spin related measurements at short distance, performed at PHENIX, STAR, BRAHMS, HERMES, COMPASS and Belle will be given.
Analysis of DIS structure functions of the nucleon within truncated Mellin moments approach
Kotlorz, D
2016-01-01
We present generalized evolution equations and factorization in terms of the truncated Mellin moments (TMM) of the parton distributions and structure functions. We illustrate the $x$ and $Q^2$ dependence of TMM in the polarized case. Using the TMM approach we compare the integrals of $g_1$ with HERMES and COMPASS data from the limited $x$-ranges.
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
Nucleon structure functions from. nu. sub. mu. -Fe scattering at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Smith, W.H.; Sandler, P.H. (Wisconsin Univ., Madison (USA)); Merritt, F.S.; Oreglia, M.J.; Schumm, B.A. (Chicago Univ., IL (USA)); Arroyo, C.; Bachmann, K.T.; Blair, R.E.; Foudas, C.; King, B.J.; Lefmann, W.C.; Leung, W.C.; Mishra, S.R.; Oltman, E.; Quintas, P.Z.; Rabinowitz, S.A.; Sciulli, F.J.; Seligman, W.G.; Shaevitz, M.H. (Columbia Univ., New York (USA)); Bernstein, R.H.; Borcherding, F.O.; Fisk, H.E.; Lamm, M.J.; Marsh, W.; Merritt, K.W.; Schellman, H.; Yovanovitch, D. (Fermi National Accelerator Lab., Batavia, IL (USA)); Bodek, A.; Budd, H.S.; De Barbaro, P.; Sakumoto, W.K. (Rochester Univ., NY (USA))
1991-04-01
Preliminary measurements of structure functions have been made from a sample of 1,281,000 {nu}{sub {mu}} and 270,000 anti {nu}{sub {mu}} charged current events with 30 GeV < E{sub {nu}} < 600 GeV. These include a new value of the Gross-Llewellyn Smith Sum Rule, {integral} (1/x)(xF{sub 3})dx = 2.66 {+-} .03 (stat) {+-} .08 (syst), the ratio of cross sections, {sigma}(anti {nu}{sub {mu}})/{sigma}({nu}{sub {mu}}) = .511 {+-} .002 (stat) {+-} .005 (syst), and an analysis of the Q{sup 2} evolution of xF{sub 3}. (orig.).
Nejad, S Mohammad Moosavi; Tehrani, S Atashbar; Mahdavi, Mahdi
2016-01-01
We present a detailed QCD analysis of nucleon structure functions $xF_3 (x, Q^2)$, based on Laplace transforms and Jacobi polynomials approach. The analysis corresponds to the next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) approximation of perturbative QCD. The Laplace transform technique, as an exact analytical solution, is used for the solution of nonsinglet DGLAP evolution equations at low- and large-$x$ values. The extracted results are used as input to obtain the $x$ and Q$^2$ evolution of $xF_3(x, Q^2)$ structure functions using the Jacobi polynomials approach. In our work, the values of the typical QCD scale $\\Lambda_{\\overline{\\rm MS}}^{(n_f)}$ and the strong coupling constant $\\alpha_s(M_Z^2)$ are determined for four quark flavors ($n_f=4$) as well. A careful estimation of the uncertainties shall be performed using the Hessian method for the valence-quark distributions, originating from the experimental errors. We compare our valence-quark PDFs sets with those of other collabora...
Chiral nucleon-nucleon forces in nuclear structure calculations
Directory of Open Access Journals (Sweden)
Coraggio L.
2016-01-01
Full Text Available Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
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.
Gravitational form factors and nucleon spin structure
Teryaev, O. V.
2016-10-01
Nucleon scattering by the classical gravitational field is described by the gravitational (energy-momentum tensor) form factors (GFFs), which also control the partition of nucleon spin between the total angular momenta of quarks and gluons. The equivalence principle (EP) for spin dynamics results in the identically zero anomalous gravitomagnetic moment, which is the straightforward analog of its electromagnetic counterpart. The extended EP (ExEP) describes its (approximate) validity separately for quarks and gluons and, in turn, results in equal partition of the momentum and total angular momentum. It is violated in quantum electrodynamics and perturbative quantum chromodynamics (QCD), but may be restored in nonperturbative QCD because of confinement and spontaneous chiral symmetry breaking, which is supported by models and lattice QCD calculations. It may, in principle, be checked by extracting the generalized parton distributions from hard exclusive processes. The EP for spin-1 hadrons is also manifested in inclusive processes (deep inelastic scattering and the Drell-Yan process) in sum rules for tensor structure functions and parton distributions. The ExEP may originate in either gravity-proof confinement or in the closeness of the GFF to its asymptotic values in relation to the mediocrity principle. The GFFs in time-like regions reveal some similarity between inflation and annihilation.
Meson-cloud effects in the electromagnetic nucleon structure
Kupelwieser, Daniel
2013-01-01
We study how the electromagnetic structure of the nucleon is influenced by a pion cloud. To this aim we make use of a constituent-quark model with instantaneous confinement and a pion that couples directly to the quarks. To derive the invariant 1- photon-exchange electron-nucleon scattering amplitude we employ a Poincar\\'e- invariant coupled-channel formulation which is based on the point-form of relativistic quantum mechanics. We argue that the electromagnetic nucleon current extracted from this amplitude can be reexpressed in terms of pure hadronic degrees of freedom with the quark substructure of the pion and the nucleon being encoded in electromagnetic and strong vertex form factors. These are form factors of bare particles, i.e. eigenstates of the pure confinement problem. First numerical results for (bare) photon-nucleon and pion-nucleon form factors, which are the basic ingredients of the further calculation, are given for a simple 3-quark wave function of the nucleon.
Probing nuclear structure with nucleons; Sonder la structure nucleaire avec des nucleons
Energy Technology Data Exchange (ETDEWEB)
Bauge, E. [CEA Bruyeres-le-Chatel, Service de Physique Nucl aire, 91 (France)
2007-07-01
The goal of this lecture is to show how nucleon scattering can be used to probe the structure of target nuclei, and how nucleon scattering observables can be interpreted in terms of nuclear structure using microscopic optical potentials. After a brief overview of the specificities of nucleon-nucleus scattering, and a quick reminder on scattering theory, the main part of this lecture is devoted to the construction of optical potentials in which the target nuclei structure information is folded with an effective interaction. Several examples of such microscopic optical model potentials are given. (author)
New insights into the spin structure of the nucleon
Bernard, V; Krebs, H; Meißner, U -G
2012-01-01
We analyze the low-energy spin structure of the nucleon in a covariant effective field theory with explicit spin-3/2 degrees of freedom to third order in the small scale expansion. Using the available data on the strong and electromagnetic width of the Delta-resonance, we give parameter-free predictions for various spin-polarizabilities and moments of spin structure functions. We find an improved description of the nucleon spin structure at finite photon virtualities for some observables and point out the necessity of a fourth order calculation.
A covariant model for the nucleon spin structure
Ramalho, G
2015-01-01
We present the results of the covariant spectator quark model applied to the nucleon structure function $f(x)$ measured in unpolarized deep inelastic scattering, and the structure functions $g_1(x)$ and $g_2(x)$ measured in deep inelastic scattering using polarized beams and targets ($x$ is the Bjorken scaling variable). The nucleon is modeled by a valence quark-diquark structure with $S,P$ and $D$ components. The shape of the wave functions and the relative strength of each component are fixed by making fits to the deep inelastic scattering data for the structure functions $f(x)$ and $g_1(x)$. The model is then used to make predictions on the function $g_2(x)$ for the proton and neutron.
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.
Liang, Y; Ahmidouch, A; Armstrong, C S; Arrington, J; Asaturyan, R; Avery, S; Baker, O K; Beck, D H; Blok, H P; Bochna, C W; Böglin, W; Bosted, P; Bouwhuis, M; Breuer, H; Brown, D S; Brüll, A; Carlini, R D; Cha, J; Chant, N S; Cochran, A; Cole, L; Danagulyan, S; Day, D B; Dunne, J; Dutta, D; Ent, R; Fenker, H C; Fox, B; Gan, L; Gao, H; Garrow, K; Gaskell, D; Gasparian, A; Geesaman, D F; Gilman, R; Gueye, P L J; Harvey, M; Holt, R J; Jiang, X; Jones, M; Keppel, C E; Kinney, E; Lorenzon, W; Lung, A; Mack, D J; Markowitz, P; Martin, J W; McIlhany, K; McKee, D; Meekins, D; Miller, M A; Milner, R G; Mitchell, J H; Mkrtchyan, H G; Müller, B A; Nathan, A; Niculescu, G; Niculescu, I; O'Neill, T G; Papavassiliou, V; Pate, S F; Piercey, R B; Potterveld, D; Ransome, R D; Reinhold, J; Rollinde, E; Rondon, Oscar A; Roos, P; Sarty, A J; Sawafta, R; Schulte, E C; Segbefia, E; Smith, C; Stepanyan, S; Strauch, S; Tadevosyan, V; Tang, L; Tieulent, R; Tvaskis, V; Uzzle, A; Vulcan, W F; Wood, S A; Xiong, F; Yuan, L; Zeier, M; Zihlmann, B; Ziskin, V
2004-01-01
We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q^2 < 5.5 GeV^2. The data have been used to accurately perform over 170 Rosenbluth-type longitudinal / transverse separations. The precision R = sigma_L / sigma_T data are presented here, along with the first separate values of the inelastic structure functions F_1 and F_L in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q^2 = 1 GeV^2 in the separated structure functions independently.
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.
The nucleon wave function in light-front dynamics
Karmanov, V A
1998-01-01
The general spin structure of the relativistic nucleon wave function in the $3q$-model is found. It contains 16 spin components, in contrast to 8 ones known previously, since in a many-body system the parity conservation does not reduce the number of the components. The explicitly covariant form of the wave function automatically takes into account the relativistic spin rotations, without introducing any Melosh rotation matrices. It also reduces the calculations to the standard routine of the Dirac matrices and of the trace techniques. In examples of the proton magnetic moment and of the axial nucleon form factor, with a particular wave function, we reproduce the results of the standard approach. Calculations beyond the standard assumptions give different results.
Electromagnetic studies of nucleon and nuclear structure
Energy Technology Data Exchange (ETDEWEB)
Heisenberg, J.H.; Calarco, J.R.; Hersman, F.W.; Dawson, J.F.
1993-06-01
Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on {sup 12}C and {sup 16}O are reported, as well as work on nuclear structure models and instrumentation development.
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...
Nucleon structure from 2+1-flavor dynamical DWF ensembles
Abramczyk, Michael; Lytle, Andrew; Ohta, Shigemi
2016-01-01
Nucleon isovector vector- and axialvector-current form factors, the renormalized isovector transversity and scalar charge, and the bare quark momentum and helicity moments of isovector structure functions are reported with improved statistics from two recent RBC+UKQCD 2+1-flavor dynamical domain-wall fermions ensembles: Iwasaki\\(\\times\\)DSDR gauge \\(32^3\\times64\\) at inverse lattice spacing of 1.38 GeV and pion mass of 249 and 172 MeV.
Panofsky Prize talk: The Structure of the Nucleon
Bodek, Arie
2004-05-01
Information about the quark distribution functions in nucleons and nuclei has been obtained from a range of experiments in various laboratories including electron-nucleon/nucleus, neutrino-nucleon/nucleus, and production of W and Z Bosons in proton-antiproton collisions. I review the the different experimental and theoretical tools that were developed to extract parton distribution functions from these experiments with very different probes.
The SAMPLE Experiment and Weak Nucleon Structure
Beise, E J; Spayde, D T
2004-01-01
One of the key elements to understanding the structure of the nucleon is the role of its quark-antiquark sea in its ground state properties such as charge, mass, magnetism and spin. In the last decade, parity-violating electron scattering has emerged as an important tool in this area, because of its ability to isolate the contribution of strange quark-antiquark pairs to the nucleon's charge and magnetism. The SAMPLE experiment at the MIT-Bates Laboratory, which has been focused on s-sbar contributions to the proton's magnetic moment, was the first of such experiments and its program has recently been completed. In this paper we give an overview of some of the experimental aspects of parity-violating electron scattering, briefly review the theoretical predictions for strange quark form factors, summarize the SAMPLE measurements, and place them in context with the program of experiments being carried out at other electron scattering facilities such as Jefferson Laboratory and the Mainz Microtron.
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.)
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 structure studies with the COMPASS experiment at CERN
Platchkov, Stephane
2016-11-01
The COMPASS experiment at CERN uses hadron and lepton beams for nucleon structure studies. Most of the data collected so far with a muon beam and either proton or deuteron polarised target were analysed in terms of longitudinally or transversely polarised parton distribution functions and transverse momentum-dependent distributions in the nucleon. A negative hadron beam is used to perform Drell-Yan measurements. The COMPASS large polarised target gives access to several momentum-dependent singlespin asymmetries and provides a stringent test of the fundamental QCD factorisation assumptions. With positive and negative muon beams COMPASS also studies Generalised Parton Distributions using exclusive deeply virtual Compton scattering and meson production experiments. An overview of the most recent COMPASS results is given. The expected physics outcome of the forthcoming measurements is discussed.
The structure of the nucleon: Elastic electromagnetic form factors
Energy Technology Data Exchange (ETDEWEB)
Punjabi, V. [Norfolk State University, Norfolk, VA (United States); Perdrisat, C.F.; Carlson, C.E. [The College of William and Mary, Williamsburg, VA (United States); Jones, M.K. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Brash, E.J. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Christopher Newport University, Newport News, VA (United States)
2015-07-15
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.)
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.
Nucleon Structure and hyperon form factors from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Lin, Huey-Wen
2007-06-11
In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point to be 1.23(5), consistant with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(26), consistent with the Adelaide-JLab Collaboration's result. The hyperon Sigma and Xi axial coupling constants are also performed for the first time in a lattice calculation, g_SigmaSigma = 0.441(14) and g_XiXi = -0.277(11).
Nucleon Structure and Hyperon Form Factors from Lattice QCD.
Energy Technology Data Exchange (ETDEWEB)
Lin,H.W.
2007-06-11
In this work, I report the latest lattice QCD calculations of nucleon and hyperon structure from chiral fermions in 2+1-flavor dynamical simulations. All calculations are done with a chirally symmetric fermion action, domain-wall fermions, for valence quarks. I begin with the latest lattice results on the nucleon structure, focusing on results from RBC/UKQCD using 2+1-flavor chiral fermion actions. We find the chiral-extrapolated axial coupling constant at physical pion mass point. to be 1.23(5), consistent with experimental value. The renormalization constants for the structure functions are obtained from RI/MOM-scheme non-perturbative renormalization. We find first moments of the polarized and unpolarized nucleon structure functions at zero transfer momentum to be 0.133(13) and 0.203(23) respectively, using continuum chiral extrapolation. These are consistent with the experimental values, unlike previous calculations which have been 50% larger. We also have a prediction for the transversity, which we find to be 0.56(4). The twist-3 matrix element is consistent with zero which agrees with the prediction of the Wandzura-Wilczek relation. In the second half of this work, I report an indirect dynamical estimation of the strangeness proton magnetic moments using mixed actions. With the analysis of hyperon form factors and using charge symmetry, the strangeness of proton is found to be -0.066(2G), consistent with the Adelaide-JLab Collaboration's result. The hyperon {Sigma} and {Xi} axial coupling constants are also performed for the first time in a lattice calculation, g{sub {Sigma}{Sigma}} = 0.441(14) and g{sub {Xi}{Xi}} = -0.277(11).
Short-range correlations of partons & 3D nucleon structure
Directory of Open Access Journals (Sweden)
Schweitzer P.
2014-03-01
Full Text Available Dynamical breaking of chiral symmetry in QCD is caused by non-perturbative interactions on a scale ρ ∼ 0.3 fm much smaller than the hadronic size R ∼ 1 fm. This has important consequences for the nucleon structure such as the prediction that the transverse momentum distribution of sea quarks is significantly broader than the pT -distribution of valence quarks due to short-range correlations between sea quarks in the nucleon’s light-cone wave function.
Lattice QCD Calculation of Nucleon Structure
Energy Technology Data Exchange (ETDEWEB)
Liu, Keh-Fei [University of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy; Draper, Terrence [University of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy
2016-08-30
It is emphasized in the 2015 NSAC Long Range Plan that "understanding the structure of hadrons in terms of QCD's quarks and gluons is one of the central goals of modern nuclear physics." Over the last three decades, lattice QCD has developed into a powerful tool for ab initio calculations of strong-interaction physics. Up until now, it is the only theoretical approach to solving QCD with controlled statistical and systematic errors. Since 1985, we have proposed and carried out first-principles calculations of nucleon structure and hadron spectroscopy using lattice QCD which entails both algorithmic development and large-scale computer simulation. We started out by calculating the nucleon form factors -- electromagnetic, axial-vector, πNN, and scalar form factors, the quark spin contribution to the proton spin, the strangeness magnetic moment, the quark orbital angular momentum, the quark momentum fraction, and the quark and glue decomposition of the proton momentum and angular momentum. The first round of calculations were done with Wilson fermions in the `quenched' approximation where the dynamical effects of the quarks in the sea are not taken into account in the Monte Carlo simulation to generate the background gauge configurations. Beginning in 2000, we have started implementing the overlap fermion formulation into the spectroscopy and structure calculations. This is mainly because the overlap fermion honors chiral symmetry as in the continuum. It is going to be more and more important to take the symmetry into account as the simulations move closer to the physical point where the u and d quark masses are as light as a few MeV only. We began with lattices which have quark masses in the sea corresponding to a pion mass at ~ 300 MeV and obtained the strange form factors, charm and strange quark masses, the charmonium spectrum and the D_{s} meson decay constant f_{Ds}, the strangeness and charmness, the meson mass
Lattice QCD Calculation of Nucleon Structure
Energy Technology Data Exchange (ETDEWEB)
Liu, Keh-Fei; Draper, Terrence
2016-08-30
It is emphasized in the 2015 NSAC Long Range Plan [1] that \\understanding the structure of hadrons in terms of QCD's quarks and gluons is one of the central goals of modern nuclear physics." Over the last three decades, lattice QCD has developed into a powerful tool for ab initio calculations of strong-interaction physics. Up until now, it is the only theoretical approach to solving QCD with controlled statistical and systematic errors. Since 1985, we have proposed and carried out rst-principles calculations of nucleon structure and hadron spectroscopy using lattice QCD which entails both algorithmic development and large scale computer simulation. We started out by calculating the nucleon form factors { electromagnetic [2], axial-vector [3], NN [4], and scalar [5] form factors, the quark spin contribution [6] to the proton spin, the strangeness magnetic moment [7], the quark orbital angular momentum [8], the quark momentum fraction [9], and the quark and glue decomposition of the proton momentum and angular momentum [10]. These rst round of calculations were done with Wilson fermions in the `quenched' approximation where the dynamical e ects of the quarks in the sea are not taken into account in the Monte Carlo simulation to generate the background gauge con gurations. Beginning in 2000, we have started implementing the overlap fermion formulation into the spectroscopy and structure calculations [11, 12]. This is mainly because the overlap fermion honors chiral symmetry as in the continuum. It is going to be more and more important to take the symmetry into account as the simulations move closer to the physical point where the u and d quark masses are as light as a few MeV only. We began with lattices which have quark masses in the sea corresponding to a pion mass at 300 MeV and obtained the strange form factors [13], charm and strange quark masses, the charmonium spectrum and the Ds meson decay constant fDs [14], the strangeness and charmness [15], the
Probing nucleon strangeness structure with $\\phi$ electroproduction
Oh, Yu; Yang, S N; Mori, T; Oh, Yongseok; Titov, Alexander I.; Yang, Shin Nan; Morii, Toshiyuki
1999-01-01
We study the possibility to constrain the hidden strangeness content of the nucleon by means of the polarization observables in phi meson electroproduction. We consider the OZI evading direct knockout mechanism that arises from the non-vanishing s\\bar{s} sea quark admixture of the nucleon as well as the background of the dominant diffractive and the one-boson-exchange processes. Large sensitivity on the nucleon strangeness are found in several beam-target and beam-recoil double polarization observables. The small \\sqrt{s} and W region, which is accesible at some of the current high-energy electron facilities, is found to be the optimal energy region for extracting out the OZI evasion process.
Experimental study of the nucleon spin structure
Energy Technology Data Exchange (ETDEWEB)
Litmaath, M.F.
1996-05-07
After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.).
Multi-Nucleon Short-Range Correlation Model for Nuclear Spectral Functions.
Artiles, Oswaldo; Sargsian, Misak
2017-01-01
We develop a theoretical model for nuclear spectral functions at high missing momenta and energies based on the multi-nucleon short-range correlation (SRC) model aimed at probing nuclear structure at short-distances. The model is based on the effective Feynman diagram method which allows us to account for the relativistic effects in the SRC domain. We derive the contribution of two-nucleon SRC with center of mass motion, and three-nucleon SRCs to the nuclear spectral functions. The spectral functions are based on two theoretical approaches in evaluating covariant Feynman diagrams: In the first, referred to as virtual nucleon approximation, we reduce Feynman diagrams to the time ordered non-covariant diagrams by evaluating nucleon spectators on the SRC at their positive energy poles, neglecting the contribution from vacuum diagrams. In the second approach, referred to as light-front approximation, we formulate the boost invariant nuclear spectral function on the light-front reference frame, on which the vacuum diagrams are suppressed. Numerical calculations and parametrization of spectral functions and momentum distributions are presented. This work is supported by U.S. Department of Energy grant under contract DE- FG02-01ER41172.
Nucleon and Delta structure in continuum QCD
Cloet, Ian
2014-03-01
Quantum Chromodynamics (QCD) is the only known example in nature of a fundamental quantum field theory that is innately non-perturbative. Solving QCD will have profound implications for our understanding of the natural world, for example, it will explain how light quarks and massless gluons bind together to form the observed mesons and baryons; hence explaining the origin of more than 98% of the mass in the visible universe. Given the challenges posed by QCD, it is insufficient to study hadron ground-states alone if one seeks a solution; in this regard the delta plays a special role as the lightest baryon resonance. I will discuss recent progress using continuum QCD approaches to the study of nucleon and delta properties, with a focus on insights gained by the calculation (and measurement) of their electromagnetic form factors.
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.)
Abramowicz, H; Duda, J; Dydak, F; Eisele, F; Flottmann, T; Geweniger, C; Guyot, C; He, J T; Klasen, H P; Kleinknecht, K; Knobloch, J; Królikowski, J; May, J; Merlo, J P; Palazzi, P; Para, A; Peyaud, B; Pszola, B; Rander, J; Ranjard, F; Renk, B; Rothberg, J E; Ruan, T Z; Schlatter, W D; Schuller, J P; Steinberger, J; Taureg, H; Tittel, K; Turlay, René; von Rüden, Wolfgang; Wahl, H; Willutzki, H J; Wotschack, J; Wu, W M
1982-01-01
The scaling violations of the structure functions F/sub 2/, xF/sub 3/, and q, as measured in deep-inelastic neutrino-nucleon scattering at high hadron class W, have been compared with the predictions of QCD and other candidate field theories of strong interactions. Non- asymptotically free theories with scalar and vector gluons are incompatible with the data. This leaves QCD as the only field theory that gives a consistent description of all the observed scaling violations. The data do not, however, permit a sensitive test of the existence of the gluon self-coupling.
$pp$ Elastic Scattering at LHC and Nucleon Structure
Islam, M M; Prokudin, A V
2003-01-01
High energy elastic pp differential cross section at LHC at the c.m. energy 14 TeV is predicted using the asymptotic behavior of sigma-tot(s) and rho(s), and the measured pbar-p differential cross section at sqrt{s}=546 GeV. The phenomenological investigation has progressively led to an effective field theory model that describes the nucleon as a chiral bag embedded in a quark-antiquark condensed ground state. The measurement of pp elastic scattering at LHC up to large |t| >~ 10 GeV^2 by the TOTEM group will be crucial to test this structure of the nucleon.
Delineating the polarized and unpolarized partonic structure of the nucleon
Jimenez-Delgado, Pedro
2014-01-01
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.
Interacting boson models of nuclear and nucleon structure
Bijker, R
1998-01-01
Interacting boson models provide an elegant and powerful method to describe collective excitations of complex systems by introducing a set of effective degrees of freedom. We review the interacting boson model of nuclear structure and discuss a recent extension to the nucleon and its excited states.
Spin structure of the nucleon on the light front
Lorcé, Cédric
2014-01-01
We briefly review the spin structure of the nucleon and show that it is best thought in the light-front formulation. We discuss in particular the longitudinal and transverse spin sum rules, the proper definition of canonical orbital angular momentum and the spin-orbit correlation.
Numerical Toy-Model Calculation of the Nucleon Spin Autocorrelation Function in a Supernova Core
Raffelt, G G; Raffelt, Georg; Sigl, Guenter
1999-01-01
We develop a simple model for the evolution of a nucleon spin in a hot and dense nuclear medium. A given nucleon is limited to one-dimensional motion in a distribution of external, spin-dependent scattering potentials. We calculate the nucleon spin autocorrelation function numerically for a variety of potential densities and distributions which are meant to bracket realistic conditions in a supernova core. For all plausible configurations the width of the spin-density structure function is found to be less than the temperature. This is in contrast with a naive perturbative calculation based on the one-pion exchange potential which overestimates the width and thus suggests a large suppression of the neutrino opacities by nucleon spin fluctuations. Our results suggest that it may be justified to neglect the collisional broadening of the spin-density structure function for the purpose of estimating the neutrino opacities in the deep inner core of a supernova. On the other hand, we find no indication that process...
Di-nucleon structures in homogeneous nuclear matter based on two- and three-nucleon interactions
Energy Technology Data Exchange (ETDEWEB)
Arellano, Hugo F. [University of Chile, Department of Physics - FCFM, Santiago (Chile); CEA, DAM, DIF, Arpajon (France); Isaule, Felipe [University of Chile, Department of Physics - FCFM, Santiago (Chile); Rios, Arnau [University of Surrey, Department of Physics, Faculty of Engineering and Physical Sciences, Guildford (United Kingdom)
2016-09-15
We investigate homogeneous nuclear matter within the Brueckner-Hartree-Fock (BHF) approach in the limits of isospin-symmetric nuclear matter (SNM) as well as pure neutron matter at zero temperature. The study is based on realistic representations of the internucleon interaction as given by Argonne v{sub 18}, Paris, Nijmegen I and II potentials, in addition to chiral N{sup 3}LO interactions, including three-nucleon forces up to N{sup 2}LO. Particular attention is paid to the presence of di-nucleon bound states structures in {sup 1}S{sub 0} and {sup 3}SD{sub 1} channels, whose explicit account becomes crucial for the stability of self-consistent solutions at low densities. A characterization of these solutions and associated bound states is discussed. We confirm that coexisting BHF single-particle solutions in SNM, at Fermi momenta in the range 0.13-0.3 fm{sup -1}, is a robust feature under the choice of realistic internucleon potentials. (orig.)
The Spin Structure of the Nucleon:. a Hughes Legacy
Cates, Gordon D.
2004-12-01
More than any other individual, Vernon Hughes can be pointed to as the father of the experimental investigation of nucleon spin structure. Even theoretical development in this area was spurred on by Vernon's pioneering efforts to make the control of spin degrees of freedom an experimental reality. This talk traces some of Vernon's work in this area, as well as examining, briefly and not in a complete fashion, some of the other work that can be looked upon as Vernon's legacy.
Transverse spin structure of the nucleon from lattice QCD simulations
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M.; Schaefer, A. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik; Haegeler, P. [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y.; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division, Dept. of Mathematical Sciences; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB) (Germany)
2006-12-15
We present the first calculation in lattice QCD of the lowest two moments of transverse spin densities of quarks in the nucleon. They encode correlations between quark spin and orbital angular momentum. Our dynamical simulations are based on two flavors of clover-improved Wilson fermions and Wilson gluons. We find significant contributions from certain quark helicity flip generalized parton distributions, leading to strongly distorted densities of transversely polarized quarks in the nucleon. In particular, based on our results and recent arguments by Burkardt [Phys. Rev. D 72 (2005) 094020], we predict that the Boer-Mulders-function h{sub 1} {sup perpendicular} {sup to}, describing correlations of transverse quark spin and intrinsic transverse momentum of quarks, is large and negative for both up and down quarks. (orig.)
Statistical effect in the parton distribution functions of the nucleon
Zhang, Yunhua; Ma, Bo-Qiang
2008-01-01
A new and simple statistical approach is performed to calculate the parton distribution functions (PDFs) of the nucleon in terms of light-front kinematic variables. We do not put in any extra arbitrary parameter or corrected term by hand, which guarantees the stringency of our approach. Analytic expressions of the $x$-dependent PDFs are obtained in the whole $x$ region [0,1], and some features, especially the low-$x$ rise, are more agreeable with experimental data than those in some previous instant-form statistical models in the infinite-momentum frame (IMF). Discussions on heavy-flavored PDFs are also presented.
Chiral Corrections to Nucleon Two- and Three-Point Correlation Functions
Tiburzi, Brian C
2015-01-01
We consider multi-particle contributions to nucleon two- and three-point functions from the perspective of chiral dynamics. Lattice nucleon interpolating operators, which have definite chiral transformation properties, can be mapped into chiral perturbation theory. Using the most common of such operators, we determine pion-nucleon and pion-delta couplings to nucleon two- and three-point correlation functions at leading order in the low-energy expansion. The couplings of pions to nucleons and deltas in two-point functions are consistent with simple phase-space considerations, in accordance with the Lehmann spectral representation. An argument based on available phase space on a torus is utilized to derive the scaling of multiple-pion couplings. While multi-pion states are indeed suppressed, this suppression scales differently with particle number compared to that in infinite volume. For nucleon three-point correlation functions, we investigate the axial-vector current at vanishing momentum transfer. The effect...
Covariant nucleon wave function with S, D, and P-state components
Gross, Franz; Pena, M T
2012-01-01
Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.
Covariant nucleon wave function with S, D, and P-state components
Energy Technology Data Exchange (ETDEWEB)
Franz Gross, G. Ramalho, M. T. Pena
2012-05-01
Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.
Polarized lepton-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Hughes, E.
1994-02-01
Deep inelastic polarized lepton-nucleon scattering is reviewed in three lectures. The first lecture covers the polarized deep inelastic scattering formalism and foundational theoretical work. The second lecture describes the nucleon spin structure function experiments that have been performed up through 1993. The third lecture discusses implication of the results and future experiments aimed at high-precision measurements of the nucleon spin structure functions.
Cao, X. G.; Cai, X. Z.; Ma, Y. G.; Fang, D. Q.; Zhang, G. Q.; Guo, W.; Chen, J. G.; Wang, J. S.
2012-10-01
Proton-neutron, neutron-neutron, and proton-proton momentum-correlation functions (Cpn,Cnn, and Cpp) are systematically investigated for 15C and other C-isotope-induced collisions at different entrance channel conditions within the framework of the isospin-dependent quantum-molecular-dynamics model complemented by the correlation after burner (crab) computation code. 15C is a prime exotic nucleus candidate due to the weakly bound valence neutron coupling with closed-neutron-shell nucleus 14C. To study density dependence of the correlation function by removing the isospin effect, the initialized 15C projectiles are sampled from two kinds of density distribution from the relativistic mean-field (RMF) model in which the valence neutron of 15C is populated in both 1d5/2 and 2s1/2 states, respectively. The results show that the density distributions of the valence neutron significantly influence the nucleon-nucleon momentum-correlation function at large impact parameters and high incident energies. The extended density distribution of the valence neutron largely weakens the strength of the correlation function. The size of the emission source is extracted by fitting the correlation function by using the Gaussian source method. The emission source size as well as the size of the final-state phase space are larger for projectile samplings from more extended density distributions of the valence neutron, which corresponds to the 2s1/2 state in the RMF model. Therefore, the nucleon-nucleon momentum-correlation function can be considered as a potentially valuable tool to diagnose exotic nuclear structures, such as the skin and halo.
Navarro Pérez, R.; Amaro, J. E.; Ruiz Arriola, E.
2016-11-01
We analyze the low-energy nucleon-nucleon (NN) interaction by confronting statistical versus systematic uncertainties. This is carried out with the help of model potentials fitted to the Granada-2013 database where a statistically meaningful partial wave analysis comprising a total of 6713 np and pp published scattering data below 350 MeV from 1950 till 2013 has been made. We extract threshold parameter uncertainties from the coupled-channel effective range expansion up to j≤slant 5. We find that for threshold parameters systematic uncertainties are generally at least an order of magnitude larger than statistical uncertainties. Similar results are found for np phase shifts and amplitude parameters.
Low temperature polarized target for spin structure studies of nucleons at COMPASS
Pesek, Michael
In presented thesis we describe concept of Deep Inelastic Scattering of leptons on nucleons in context of nucleon spin structure studies. Both polarized and unpolarized cases are discussed and concept of Transverse Momentum Dependent Parton Distribution Functions (TMD PDF) is introduced. The possibility of TMDs measurement using Semi-inclusive DIS (SIDIS) is described along with related results from COMPASS experiment. The future Drell-Yan programme at COMPASS is briefly mentioned and its importance is presented on the universality test i.e. change of sign of T-odd TMDs when measured in Drell-Yan and SIDIS. The importance of Polarized Target (PT) for spin structure studies is highlighted and principles of Dynamic Nuclear Polarization (DNP) are given using both Solid effect and spin temperature concept. COMPASS experiment is described in many details with accent given to PT. Finally the thermal equilibrium (TE) calibration procedure is described and carried out for 2010 and 2011 physics runs at COMPASS. The av...
Nucleon electromagnetic structure studies in the spacelike and timelike regions
Energy Technology Data Exchange (ETDEWEB)
Guttmann, Julia
2013-07-23
The thesis investigates the nucleon structure probed by the electromagnetic interaction. One of the most basic observables, reflecting the electromagnetic structure of the nucleon, are the form factors, which have been studied by means of elastic electron-proton scattering with ever increasing precision for several decades. In the timelike region, corresponding with the proton-antiproton annihilation into a electron-positron pair, the present experimental information is much less accurate. However, in the near future high-precision form factor measurements are planned. About 50 years after the first pioneering measurements of the electromagnetic form factors, polarization experiments stirred up the field since the results were found to be in striking contradiction to the findings of previous form factor investigations from unpolarized measurements. Triggered by the conflicting results, a whole new field studying the influence of two-photon exchange corrections to elastic electron-proton scattering emerged, which appeared as the most likely explanation of the discrepancy. The main part of this thesis deals with theoretical studies of two-photon exchange, which is investigated particularly with regard to form factor measurements in the spacelike as well as in the timelike region. An extraction of the two-photon amplitudes in the spacelike region through a combined analysis using the results of unpolarized cross section measurements and polarization experiments is presented. Furthermore, predictions of the two-photon exchange effects on the e{sup +}p/e{sup -}p cross section ratio are given for several new experiments, which are currently ongoing. The two-photon exchange corrections are also investigated in the timelike region in the process p anti p → e{sup +}e{sup -} by means of two factorization approaches. These corrections are found to be smaller than those obtained for the spacelike scattering process. The influence of the two-photon exchange corrections on
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...
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...
Nonequilibrium distribution functions of nucleons in relativistic nucleus-nucleus collisions
Anchishkin, D; Cleymans, J; 10.5488/CMP.16.13201
2013-01-01
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, which depend on a certain number of collisions of a nucleon before freeze-out, are derived.
Manifestation of Symmetry Properties of Nucleon Structure in Strong and Electromagnetic Processes
Tomasi-Gustafsson, Egle; Rekalo, Michail P.
2004-04-01
In this contribution we present a specific application of a result obtained by Franco Iachello (in collaboration with R. Bijker and A. Leviatan), which concerns the inelastic electromagnetic form factors on the nucleons. In particular we show examples where symmetries inherent to the structure of the nucleon resonances can manifest in complicated processes of the strong interaction.
Studies of the 3D Structure of the Nucleon at Jlab
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-07-01
Studies of the 3D structure of the nucleon encoded in Transverse Momentum Dependent distribution and fragmentation functions of partons and Generalized Parton Distributions are among the key objectives of the JLab 12 GeV upgrade and the Electron Ion Collider. Main challenges in extracting 3D partonic distributions from precision measurements of hard scattering processes include clear understanding of leading twist QCD fundamentals, higher twist effects, and also correlations of hadron production in target and current fragmentation regions. In this contribution we discuss some ongoing studies and future measurements of spin-orbit correlations at Jefferson Lab.
Studies of the 3D Structure of the Nucleon at JLab
Avakian, Harut
2016-08-01
Studies of the 3D structure of the nucleon encoded in transverse momentum dependent distribution and fragmentation functions of partons and generalized parton distributions are among the key objectives of the JLab 12 GeV upgrade and the electron ion collider. Main challenges in extracting 3D partonic distributions from precision measurements of hard scattering processes include clear understanding of leading twist QCD fundamentals, higher twist effects, and also correlations of hadron production in target and current fragmentation regions. In this contribution we discuss some ongoing studies and future measurements of spin-orbit correlations at Jefferson Lab.
Energy Technology Data Exchange (ETDEWEB)
Conger, G.; Edighoffer, J.; Grigorian, A.; Guiragossian, Z.G.T.; Hofstadter, R.; McPharlin, T.P.; Yearian, M.R.; /Stanford U.; Cox, B.C.; Peoples Jr., J.; /Fermilab
1975-10-15
The authors propose to measure the inclusive deep inelastic electron-nucleon scattering cross sections on hydrogen and deuterium. Cross sections will be measured in the range of momentum transfers Q{sub min}{sup 2} = 0.160 (GeV/c){sup 2} and Q{sub max}{sup 2} = 160.0 (GeV/c){sup 2}, in the range of recoil hadronic mass squared of W{sub min}{sup 2} = 2 GeV{sup 2} and W{sub max}{sup 2} = 450 GeV{sup 2}. The electromagnetic structure functions, {nu}W{sub 2}(Q{sup 2},{nu}) and W{sub 1}(Q{sup 2},{nu}), of both protons and neutrons will be measured and separated by well-known methods, in the highest possible unexplored FERMILAB kinematical regions. The high intensity Proton-West superconducting beam will be used to yield an electron beam of high purity, based on a synchrotron radiation compensated tuning technique. The electron beam will be used at 150 GeV (5 x 10{sup 8} e{sup {+-}}/pulse), at 175 GeV (3.6 x 10{sup 8} e{sup {+-}}/pulse) and at 250 GeV (1 x 10{sup 8} e{sup {+-}}/pulse). The scattered electron will be detected with good acceptance, good resolution and excellent identification. The detector will be the E-192 apparatus with small additions. A simple self-calibration procedure is available, both in experiment and apparatus, removing beam-associated and target-associated background in the entire (Q{sup 2}, W{sup 2}) kinematical regions. Usually, interesting physics occurs where counting rates are small. This experiment will be completely trust-worthy in such regions because their apparatus provides excellent information on the tracking and identification of scattered electrons.
Studies of the transverse structure of the nucleon at JLab
Energy Technology Data Exchange (ETDEWEB)
Mirazita, Marco [INFN, Frascati (Italy)
2014-03-01
Since the earliest measurements in the '70, hadronic physics deals with a number of surprising phenomena that cannot be explained in the framework of perturbative QCD. Examples are the small fraction of the proton spin carried by the valence quark spins, the persistence at high energies of single spin asymmetries and azimuthal asymmetries in unpolarized processes. It is now believed that the answer to these questions may come from the transverse motion of partons inside the nucleon, which is encoded in the Transverse Momentum Dependent (TMD) Parton Distribution Functions. Among the large variety of processes that can be described in terms of TMDs, a major role is played by Semi-Inclusive Deep Inelastic Scattering (SIDIS) reactions, in which, together with the scattered electron, one or more hadrons are detected in the final state. Single and Double Spin Asymmetries are the experimental observables sensitive to TMDs. The identification of the final hadrons allows the tagging of the quark involved in the reaction at the parton level, and then the flavor separation of the relevant TMDs. SIDIS reactions are studied at Jefferson Laboratories since many years and are one of the main items in the physics program after the upgrade of the CEBAF accelerator. The large amount of new data that will be available in few years calls for the implementation of new tools, such as multidimensional analyses and refined techniques of TMDs extraction from the experimental asymmetries. In this talk, the more recent results obtained at 6 GeV will be shown and the future measurements will be discussed.
Nucleon Structure in Lattice QCD using twisted mass fermions
Alexandrou, C; Korzec, T; Carbonell, J; Harraud, P A; Papinutto, M; Guichon, P; Jansen, K
2010-01-01
We present results on the nucleon form factors and moments of generalized parton distributions obtained within the twisted mass formulation of lattice QCD. We include a discussion of lattice artifacts by examining results at different volumes and lattice spacings. We compare our results with those obtained using different discretization schemes and to experiment.
Multi-Nucleon Short-Range Correlation Model for Nuclear Spectral Functions: I. Theoretical Framework
Artiles, Oswaldo
2016-01-01
We develop a theoretical approach for nuclear spectral functions at high missing momenta and removal energy based on the multi-nucleon short-range correlation~(SRC) model. The approach is based on the effective Feynman diagrammatic method which allows to account for the relativistic effects important in the SRC domain. In addition to two-nucleon SRC with center of mass motion we derived also the contribution of three-nucleon SRCs to the nuclear spectral functions. The latter is modeled based on the assumption that 3N SRCs are a product of two sequential short range NN interactions. This approach allowed us to express the 3N SRC part of the nuclear spectral function as a convolution of two NN SRCs. Thus the knowledge of 2N SRCs allows us to model both two- and three-nucleon SRC contribution to the spectral function. The derivations of the spectral functions are based on the two theoretical frameworks in evaluating covariant Feynman diagrams: In the first, referred as virtual nucleon approximation, we reduce Fe...
Nucleon resonance structure in the finite volume of lattice QCD
Wu, Jia-Jun; Lee, T -S H; Leinweber, D B; Thomas, A W
2016-01-01
An approach for relating the nucleon resonances extracted from $\\pi N$ reaction data to lattice QCD calculations has been developed by using the finite-volume Hamiltonian method. Within models of $\\pi N$ reactions, bare states are introduced to parametrize the intrinsic excitations of the nucleon. We show that the resonance pole positions can be related to the probability $P_{N^*}(E)$ of finding the bare state, $N^*$, in the $\\pi N$ scattering states in infinite volume. We further demonstrate that the probability $P_{N^*}^V(E)$ of finding the same bare states in the eigenfunctions of the underlying Hamiltonian in finite volume approaches $P_{N^*}(E)$ as the volume increases. Our findings suggest that the comparison of $P_{N^*}(E)$ and $P_{N^*}^V(E)$ can be used to examine whether the nucleon resonances extracted from the $\\pi N$ reaction data within the dynamical models are consistent with lattice QCD calculation. We also discuss the measurement of $P_{N^*}^V(E)$ directly from lattice QCD. The practical diffe...
Nucleon localization in light and heavy nuclei
Zhang, C L; Nazarewicz, W
2016-01-01
An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate $\\alpha$-cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the cluster structures in deformed light nuclei and study the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the deformed harmonic oscillator model. Realistic calculations are carried out using self-consistent nuclear density functional theory with quantified energy density functionals optimized for fission studies. We study particle densities and spatial nucleon localization distributions for deformed cluster configurations of $^{8}$Be and $^{20}$Ne, and also along...
Spin Structure Functions in a Covariant Spectator Quark Model
Energy Technology Data Exchange (ETDEWEB)
G. Ramalho, Franz Gross and M. T. Peña
2010-12-01
We apply the covariant spectator quark–diquark model, already probed in the description of the nucleon elastic form factors, to the calculation of the deep inelastic scattering (DIS) spin-independent and spin-dependent structure functions of the nucleon. The nucleon wave function is given by a combination of quark–diquark orbital states, corresponding to S, D and P-waves. A simple form for the quark distribution function associated to the P and D waves is tested.
Shell structure and few-nucleon removal in intranuclear cascade
Mancusi, Davide; Carbonell, Jaume; Cugnon, Joseph; David, Jean-Christophe; Leray, Sylvie
2014-01-01
It is well known that intranuclear-cascade models generally overestimate the cross sections for one-proton removal from heavy, stable nuclei by a high-energy proton beam, but they yield reasonable predictions for one-neutron removal from the same nuclei and for one-nucleon removal from light targets. We use simple shell-model calculations to investigate the reasons of this deficiency. We find that a correct description of the neutron skin and of the energy density in the nuclear surface is crucial for the aforementioned observables. Neither ingredient is sufficient if taken separately.
Studies of the nucleon structure in back-to-back SIDIS
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-03-01
The Deep Inelastic Scattering (DIS) proved to be a great tool in testing of the theory of strong interactions, which was a major focus in last decades. Semi-Inclusive DIS (SIDIS), with detection of an additional hadron allowed first studies of 3D structure of the nucleon, moving the main focus from testing the QCD to understanding of strong interactions and quark gluon dynamics to address a number of puzzles accumulated in recent years. Detection of two hadrons in SIDIS, which is even more complicated, provides access to details of quark gluon interactions inaccessible in single-hadron SIDIS, providing a new avenue to study the complex nucleon structure. Large acceptance of the Electron Ion Collider, allowing detection of two hadrons, produced back-to-back in the current and target fragmentation regions, combined with clear separation of two regions, would provide a unique possibility to study the nucleon structure in target fragmentation region, and correlations of target and current fragmentation regions.
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Mokeev, Victor; Burkert, Volker; Gothe, Ralf
2015-01-01
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and $N \\rightarrow N^*$ transition form factors. We will also discuss further convincing evidences for a new baryon state $N^{\\, '}(1720)3/2^+$ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Mokeev, V. I.; Aznauryan, I. G.; Burkert, V. D.; Gothe, R. W.
2016-03-01
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the γυpN* transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and N → N* transition form factors. We will also discuss further convincing evidences for a new baryon state N' (1720)3/2+ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Energy Technology Data Exchange (ETDEWEB)
Mokeev, Viktor I. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Aznauryan, Inna G. [Skobeltsyn Nuclear Physics Institute and Physics Department at Moscow State University, Moscow, Russia; Burkert, Volker D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Gothe, Ralf W. [Univ. of South Carolina, Columbia, SC (United States)
2016-03-01
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and $N \\rightarrow N^*$ transition form factors. We will also discuss further convincing evidences for a new baryon state $N^{\\, '}(1720)3/2^+$ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
Recent results on the nucleon resonance spectrum and structure from the CLAS detector
Energy Technology Data Exchange (ETDEWEB)
Mokeev, Viktor I. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Aznauryan, Inna G. [Yerevan Physics Inst. (YerPhI) (Armenia); Burkert, Volker D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Gothe, Ralf W. [Univ. of South Carolina, Columbia, SC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-03-25
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.
Experimental Studies of Quark-Gluon Structure of Nucleons and Nuclei
Energy Technology Data Exchange (ETDEWEB)
Kyle, Gary
2004-12-17
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.
A pure S-wave covariant model for the nucleon
Gross, F; Peña, M T; Gross, Franz
2006-01-01
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.
An overview of recent nucleon spin structure measurements at Jefferson Lab
Energy Technology Data Exchange (ETDEWEB)
Allada, Kalyan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-02-01
Jefferson Lab have made significant contributions to improve our knowledge of the longitudinal spin structure by measuring polarized structure functions, g1 and g2, down to Q2 = 0.02 GeV2. The low Q2 data is especially useful in testing the Chiral Perturbation theory (cPT) calculations. The spin-dependent sum rules and the spin polarizabilities, constructed from the moments of g1 and g2, provide an important tool to study the longitudinal spin structure. We will present an overview of the experimental program to measure these structure functions at Jefferson Lab, and present some recent results on the neutron polarizabilities, proton g1 at low Q2, and proton and neutron d2 measurement. In addition to this, we will discuss the transverse spin structure of the nucleon which can be accessed using chiral-odd transversity distribution (h1), and show some results from measurements done on polarized 3He target in Hall A.
Energy Technology Data Exchange (ETDEWEB)
Bratt, Jonathan; Engelhardt, Michael; Haegler, Philipp; Huey-Wen, Lin; Lin, Meifeng; Meyer, Harvey; Musch, Bernhard; Negele, John; Orginos, Konstantinos; Pochinsky, Andrew; Procura, Massimiliano; Richards, David; Schroers, Wolfram; Syritsyn, Sergey
2010-11-01
We present high statistics results for the structure of the nucleon from a mixed-action calculation using 2+1 flavors of asqtad sea and domain wall valence fermions. We perform extrapolations of our data based on different chiral effective field theory schemes and compare our results with available information from phenomenology. We discuss vector and axial form factors of the nucleon, moments of generalized parton distributions, including moments of forward parton distributions, and implications for the decomposition of the nucleon spin.
Effect of nucleon and hadron structure changes in-medium and its impact on observables
Energy Technology Data Exchange (ETDEWEB)
K. Saito; K. Tsushima; A.W. Thomas
2005-07-05
We study the effect of hadron structure changes in a nuclear medium using the quark-meson coupling (QMC) model. The QMC model is based on a mean field description of non-overlapping nucleon (or baryon) bags bound by the self-consistent exchange of scalar and vector mesons in the isoscalar and isovector channels. The model is extended to investigate the properties of finite nuclei, in which, using the Born-Oppenheimer approximation to describe the interacting quark-meson system, one can derive the effective equation of motion for the nucleon (or baryon), as well as the self-consistent equations for the meson mean fields.
The Structure of the Nucleon, Three Decades of Investigation (1967-2004)
Bodek, Arie
2005-02-01
A personal historical account of three decades of experiments that led to a detailed understanding of the structure of the nucleon and the theory of Quantum Chromodynamics. (Panofsky Prize 2004 Talk, Presented at NuInt04, Mar. 2004, Laboratori Nazionali del Gran Sasso - INFN - Assergi, Italy [ http://nuint04.lngs.infn.it/])
Can a many-nucleon structure be visible in bremsstrahlung emission during $\\alpha$ decay?
Maydanyuk, Sergei P; Zou, Li-Ping
2015-01-01
We analyze if the nucleon structure of the $\\alpha$ decaying nucleus can be visible in the experimental bremsstrahlung spectra of the emitted photons which accompany such a decay. We develop a new formalism of the bremsstrahlung model taking into account distribution of nucleons in the $\\alpha$ decaying nuclear system. We conclude the following: (1) After inclusion of the nucleon structure into the model the calculated bremsstrahlung spectrum is changed very slowly for a majority of the $\\alpha$ decaying nuclei. However, we have observed that visible changes really exist for the $^{106}{\\rm Te}$ nucleus ($Q_{\\alpha}=4.29$ MeV, $T_{1/2}$=70 mks) even for the energy of the emitted photons up to 1 MeV. This nucleus is a good candidate for future experimental study of this task. (2) Inclusion of the nucleon structure into the model increases the bremsstrahlung probability of the emitted photons. (3) We find the following tendencies for obtaining the nuclei, which have bremsstrahlung spectra more sensitive to the ...
Recent COMPASS results on the nucleon longitudinal spin structure and QCD fits
Directory of Open Access Journals (Sweden)
Andrieux Vincent
2014-01-01
Full Text Available The latest measurements of the proton longitudinal spin structure function, ɡ1p, in the deep inelastic (DIS regime are presented. They improve the statistical accuracy of the existing data and extend the kinematic domain to a lower value of x and higher values of Q2. A global NLO QCD fit of all ɡ1 world data on the proton, deuteron and neutron has been achieved. The results give a quantification of the quark spin contribution to the nucleon spin, 0.26 < ΔΣ < 0.34 at 3 (GeV/c2 in M̅S̅ scheme. The errors are dominated by the uncertainty on the shape of the functional forms assumed in the fit. A new verification of the fundamental Bjorken sum rule is obtained at a 9% level, using only COMPASS ɡ1 proton and deuteron measurements. Preliminary results of a reevaluation of the gluon polarization Δɡ/ɡ are presented. The analysis is based on double spin asymmetry of high-pT hadron production cross-sections in the DIS regime. A positive value of 〈Δɡ/ɡ〉 = 0.113 ± 0.038 ± 0.035 is obtained at leading order at x ~ 0.1. In parallel, the double spin asymmetry in the photoproduction regime is also studied. Finally, preliminary results on quark fragmentation functions into pions extracted from a LO fit of pion multiplicities in semi-inclusive DIS are presented.
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.)
Energy Technology Data Exchange (ETDEWEB)
Navratil, P; Caurier, E
2003-10-14
The authors calculate properties of A = 6 system using the accurate charge-dependent nucleon-nucleon (NN) potential at fourth order of chiral perturbation theory. By application of the ab initio no-core shell model (NCSM) and a variational calculation in the harmonic oscillator basis with basis size up to 16 {h_bar}{Omega} they obtain the {sup 6}Li binding energy of 28.5(5) MeV and a converged excitation spectrum. Also, they calculate properties of {sup 10}B using the same NN potential in a basis space of up to 8 {h_bar}{Omega}. The results are consistent with results obtained by standard accurate NN potentials and demonstrate a deficiency of Hamiltonians consisting of only two-body terms. At this order of chiral perturbation theory three-body terms appear. It is expected that inclusion of such terms in the Hamiltonian will improve agreement with experiment.
Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction
Energy Technology Data Exchange (ETDEWEB)
Aznauryan, Inna G. [Yerevan Physics Institute, JLAB; Bashir, Adnan; Braun, Vladimir M.; Brodsky, Stanley J. [SLAC; Burkert, Volker D. [JLAB; Chang, L.; Chen, Ch.; El-Bennich, Bruno O.; Cloet, Ian C.; Cole, Philip L. [Idaho State U.; Edwards, Robert G. [JLAB; Fedotov, Gleb V. [South Carolina U.; Giannini, Mauro M.; Gothe, Ralf W. [South Carolina U.; Lin, Huey-Wen [Washington; Kroll, Peter; Lee, T.-S. H.; Melnitchouk, Wally [JLAB; Mokeev, Viktor I [JLAB; Pena, Maria Teresa [CFTP; Ramalho, Gilberto T.F. [CFTP; Roberts, Craig D. [ANL; Santopinto, Elena; De Teramond, Guy F.; Tsushima, Kazuo [Adelaide U.; Wilson, David J. [Old Dominion U.
2013-06-01
The studies of N* structure represent a key direction in the N* Program with CLAS detector. After 12 GeV Upgrade, the dedicated experiment on the studies of N* structure at largest photon virtualities ever achieved Q^2<12 GeV^2 is scheduled for the first year of running with the CLAS12 detector. The current status and plans for theory support of the N* structure studies in exclusive meson electroproduction are presented. They include the recent advances in the reaction theory for extraction of N* electrocouplings from the data and the approaches for high level theoretical interpretation of these fundamental quantities, allowing us to access dynamics of non-perturbative strong interaction which is responsible for the resonance formation and explore how it emerges from QCD.
Studies of the nucleon structure in back-to-back SIDIS
Directory of Open Access Journals (Sweden)
Avakian H.
2016-01-01
Full Text Available The Deep Inelastic Scattering (DIS proved to be a great tool in testing of the theory of strong interactions, which was a major focus in last decades. Semi-Inclusive DIS (SIDIS, with detection of an additional hadron allowed first studies of 3D structure of the nucleon, moving the main focus from testing the QCD to understanding of strong interactions and quark gluon dynamics to address a number of puzzles accumulated in recent years. Detection of two hadrons in SIDIS, which is even more complicated, provides access to details of quark gluon interactions inaccessible in single-hadron SIDIS, providing a new avenue to study the complex nucleon structure. Large acceptance of the Electron Ion Collider, allowing detection of two hadrons, produced back-to-back in the current and target fragmentation regions, combined with clear separation of two regions, would provide a unique possibility to study the nucleon structure in target fragmentation region, and correlations of target and current fragmentation regions.
The full spin structure of quarks in the nucleon
Bacchetta, A; Henneman, A A; Mulders, P J
2000-01-01
We discuss bounds on the distribution and fragmentation functions that appear at leading order in deep inelastic 1-particle inclusive leptoproduction or in Drell-Yan processes. These bounds simply follow from positivity of the quark-hadron scattering matrix elements and are an important guide in estimating the magnitude of the azimuthal and spin asymmetries in these processes. We focus on an example relevant for deep inelastic scattering at relatively low energies.
NUCLEON STRUCTURE IN LATTICE QCD WITH DYNAMICAL DOMAIN--WALL FERMIONS QUARKS.
Energy Technology Data Exchange (ETDEWEB)
LIN H.-W.; OHTA, S.
2006-10-02
We report RBC and RBC/UKQCD lattice QCD numerical calculations of nucleon electroweak matrix elements with dynamical domain-wall fermions (DWF) quarks. The first, RBC, set of dynamical DWF ensembles employs two degenerate flavors of DWF quarks and the DBW2 gauge action. Three sea quark mass values of 0.04, 0.03 and 0.02 in lattice units are used with 220 gauge configurations each. The lattice cutoff is a{sup -1} {approx} 1.7GeV and the spatial volume is about (1.9fm){sup 3}. Despite the small volume, the ratio of the isovector vector and axial charges g{sub A}/g{sub V} and that of structure function moments
A novel nuclear dependence of nucleon-nucleon short-range correlations
Dai, Hongkai; Huang, Yin; Chen, Xurong
2016-01-01
A linear correlation is found between the magnitude of nucleon-nucleon short-range correlations and the nuclear binding energy per nucleon with pairing energy removed. By using this relation, the strengths of nucleon-nucleon short-range correlations of some unmeasured nuclei are predicted. Discussions on nucleon-nucleon pairing energy and nucleon-nucleon short-range correlations are made. The found nuclear dependence of nucleon-nucleon short-range correlations may shed some lights on the short-range structure of nucleus.
Contribution of Quark Structure Term in Nucleon Electric and Magnetic Form Factors
Institute of Scientific and Technical Information of China (English)
WANG Hong-Min; ZHANG Ben-Ai
2004-01-01
The constituent quarks in the nucleon have always been considered as a point-like particle in the relativistic constituent quark model. However its calculation results of GnE agree poorly with the new experimental data. The electromagnetic structure of light front constituent quarks is considered in this paper. We find that the calculation results have good agreement with the new experimental data of GnE after considering the contribution of the quark structure term. This treatment seems to be able to improve the fit to experimental data of Gep/GMp, /Q2F2p/kpF1p,and Gen/GMn as well.
Cao, X G; Ma, Y G; Fang, D Q; Zhang, G Q; Guo, W; Chen, J G; Wang, J S; 10.1103/PhysRevC.86.044620
2012-01-01
Proton-neutron, neutron-neutron and proton-proton momentum correlation functions ($C_{pn}$, $C_{nn}$, $C_{pp}$) are systematically investigated for $^{15}$C and other C isotopes induced collisions at different entrance channel conditions within the framework of the isospin-dependent quantum molecular dynamics (IDQMD) model complemented by the CRAB (correlation after burner) computation code. $^{15}$C is a prime exotic nucleus candidate due to the weakly bound valence neutron coupling with closed-neutron shell nucleus $^{14}$C. In order to study density dependence of correlation function by removing the isospin effect, the initialized $^{15}$C projectiles are sampled from two kinds of density distribution from RMF model, in which the valence neutron of $^{15}$C is populated on both 1$d$5/2 and 2$s$1/2 states, respectively. The results show that the density distributions of valence neutron significantly influence nucleon-nucleon momentum correlation function at large impact parameter and high incident energy. T...
Contribution of Quark Structure Term in Nucleon Electric and Magnetic Form Factors
Institute of Scientific and Technical Information of China (English)
WANGHong-Min; ZHANGBen-Ai
2004-01-01
The constituent quarks in the nucleon have always been considered as a point-like particle in the relativisticconstituent quark model. However its calculation results of GEn agree poorly with the new experimental data. Theelectromagnetic structure of light front constituent quarks is considered in this paper. We find that the calculationresults have good agreement with the new experimental data of GEn after considering the contribution of the quarkstructure term. This treatment seems to be able to improve the fit to experimental data of GEp/GMp,√Q2F2p/kpF1p,and GEn/GMn as well.
Study of the Nucleon Spin Structure by the Drell–Yan Process in the COMPASS-II Experiment
Quaresma, M
2012-01-01
The Parton Distribution Functions (PDFs) and the spin structure of the nucleon are important topics studied by the COMPASS experiment. The Drell–Yan (DY) process will be used in the future COMPASS-II measurements to access the Transverse Momentum Dependent PDFs (TMD PDFs). Studying the angular distributions of dimuons from the DY reactions with a negative pion beam with 190 GeV/c momentum and a transversely polarised proton target, we will be able to extract the azimuthal spin asymmetries and to access the various TMD PDFs, such as Sivers and Boer–Mulders functions. The start of the COMPASS DY experiment is scheduled for 2014. Three beam tests have been already performed, one of them in 2009 using a prototype hadron absorber downstream of the target, to understand the background reduction factors and the spectrometer response, and also to verify our results from Monte Carlo simulations. COMPASS aims at performing the first DY experiment with a transversely polarised target.
Nucleon localization and fragment formation in nuclear fission
Zhang, C. L.; Schuetrumpf, B.; Nazarewicz, W.
2016-12-01
Background: An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate α -cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Purpose: Using the spatial nucleon localization measure, we investigate the emergence of fragments in fissioning heavy nuclei. Methods: To illustrate basic concepts of nucleon localization, we employ the self-consistent energy density functional method with a quantified energy density functional optimized for fission studies. Results: We study the particle densities and spatial nucleon localization distributions along the fission pathways of 264Fm, 232Th, and 240Pu. We demonstrate that the fission fragments are formed fairly early in the evolution, well before scission. We illustrate the usefulness of the localization measure by showing how the hyperdeformed state of 232Th can be understood in terms of a quasimolecular state made of 132Sn and 100Zr fragments. Conclusions: Compared to nucleonic distributions, the nucleon localization function more effectively quantifies nucleonic clustering: its characteristic oscillating pattern, traced back to shell effects, is a clear fingerprint of cluster/fragment configurations. This is of particular interest for studies of fragment formation and fragment identification in fissioning nuclei.
Chang, Wen-Chen
2016-01-01
The observation of the violation of Lam-Tung relation in the $\\pi N$ Drell-Yan process triggered many theoretical speculations. The TMD Boer-Mulders functions characterizing the correlation of transverse momentum and transverse spin for partons in unpolarized hadrons could nicely account for the violation. The COMPASS experiment at CERN will measure the angular distributions of dimuons from the unpolarized Drell-Yan process over a wide kinematic region and study the beam particle dependence. Significant statistics is expected from a successful run in 2015 which will bring further understanding of the origin of the violation of Lam-Tung relation and of the partonic transverse spin structure of the nucleon.
Nucleon Electromagnetic Form Factors
Energy Technology Data Exchange (ETDEWEB)
Kees de Jager
2004-08-01
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.
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.
Treatment of Two Nucleons in Three Dimensions
Directory of Open Access Journals (Sweden)
Glöckle W.
2010-04-01
Full Text Available We extend a new treatment proposed for two-nucleon (2N and three-nucleon (3N bound states to 2N scattering. This technique takes momentum vectors as variables, thus, avoiding partial wave decomposition, and handles spin operators analytically. We apply the general operator structure of a nucleon-nucleon (NN potential to the NN T-matrix, which becomes a sum of six terms, each term being scalar products of spin operators and momentum vectors multiplied with scalar functions of vector momenta. Inserting this expansions of the NN force and T-matrix into the Lippmann-Schwinger equation allows to remove the spin dependence by taking traces and yields a set of six coupled equations for the scalar functions found in the expansion of the T-matrix.
Advances on statistical/thermodynamical models for unpolarized structure functions
Trevisan, Luis A.; Mirez, Carlos; Tomio, Lauro
2013-03-01
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[1] with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries ¯d/¯u and ¯d-¯u.
Formation of a necklike structure in 35Cl+12C and 197Au reactions at 43 MeV/nucleon
Larochelle, Y.; Gingras, L.; Beaulieu, L.; Qian, X.; Saddiki, Z.; Djerroud, B.; Doré, D.; Laforest, R.; Roy, R.; Samri, M.; St-Pierre, C.; Ball, G. C.; Bowman, D. R.; Galindo-Uribarri, A.; Hagberg, E.; Horn, D.; López, J. A.; Robinson, T.
1997-04-01
The experimental signature of the formation of a necklike structure, with a velocity between that of the projectilelike emitter and that of the targetlike emitter, is investigated with the same beam and experimental setup for targets lighter and heavier than the projectile. The reactions are 35Cl on 12C and on 197Au at 43 MeV/nucleon. Particle velocity distributions are compared with two-source statistical simulations and the presence of a necklike structure is inferred from the data. In the second part of the paper, dynamical model simulations with the formation of a necklike structure are presented for the 35Cl+12C system at 43 MeV/nucleon.
Nucleon-nucleon collision profile and cross section fluctuations
Rybczynski, Maciej
2013-01-01
The nucleon-nucleon collision profile, being the basic entity of the wounded nucleon model, is usually adopted in the form of hard sphere or the Gaussian shape. We suggest that the cross section fluctuations given by the gamma distribution leads to the profile function which smoothly ranges between the both limiting forms. Examples demonstrating sensitivity of profile function on cross section fluctuations are discussed.
Bound Nucleon Form Factors, Quark-Hadron Duality, and Nuclear EMC Effect
Tsushima, K; Melnitchouk, W; Saitô, K; Thomas, A W
2003-01-01
We discuss the electromagnetic form factors, axial form factors, and structure functions of a bound nucleon in the quark-meson coupling (QMC) model. Free space nucleon form factors are calculated using the improved cloudy bag model (ICBM). After describing finite nuclei and nuclear matter in the quark-based QMC model, we compute the in-medium modification of the bound nucleon form factors in the same framework. Finally, limits on the medium modification of the bound nucleon $F_2$ structure function are obtained using the calculated in-medium electromagnetic form factors and local quark-hadron duality.
Nucleon 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)
Deur, Alexandre
2009-12-01
We discuss the Jefferson Lab low momentum transfer data on moments of the nucleon spin structure functions $g_1$ and $g_2$ and on single charged pion electroproduction off polarized proton and polarized neutron. A wealth of data is now available, while more is being analyzed or expected to be taken in the upcoming years. Given the low momentum transfer selected by the experiments, these data can be compared to calculations from Chiral Perturbation theory, the effective theory of strong force that should describe it at low momentum transfer. The data on various moments and the respective calculations do not consistently agree. In particular, experimental data for higher moments disagree with the calculations.The absence of contribution from the $\\Delta$ resonance in the various observables was expected to facilitate the calculations and hence make the theory predictions either more robust or valid over a larger $Q^2$ range. Such expectation is verified only for the Bjorken sum, but not for other observables in which the $\\Delta$ is suppressed. Preliminary results on pion electroproduction off polarized nucleons are also presented and compared to phenomenological models for which contributions from different resonances are varied. Chiral Perturbation calculations of these observables, while not yet available, would be valuable and, together with these data, would provide an extensive test of the effective theory.
Parton promenade into the nucleon
Voutier, Eric
2010-01-01
Generalized parton distributions (GPDs) offer a comprehensive picture of the nucleon struture and dynamics and provide a link between microscopic and macroscopic properties of the nucleon. These quantities, which can be interpreted as the transverse distribution of partons carrying a certain longitudinal momentum fraction of the nucleon, can be accessed in deep exclusive processes. This lecture reviews the main features of the nucleon structure as obtained from elastic and inelastic lepton scatterings and unified in the context of the GPDs framework. Particular emphasis is put on the experimental methods to access these distributions and the today experimental status.
Nucleon structure with pion mass down to 149 MeV
Green, Jeremy; Krieg, Stefan; Negele, John; Pochinsky, Andrew; Syritsyn, Sergey
2012-01-01
We present isovector nucleon observables: the axial, tensor, and scalar charges and the Dirac radius. Using the BMW clover-improved Wilson action and pion masses as low as 149 MeV, we achieve good control over chiral extrapolation to the physical point. Our analysis is done using three different source-sink separations in order to identify excited-state effects, and we make use of the summation method to reduce their size.
Electromagnetic Structure of Two- and Three-Nucleon Systems: An Effective Field Theory Description
Phillips, Daniel R.
2016-10-01
I discuss the use of chiral effective field theory (χEFT) to describe electromagnetic reactions in the two- and three-nucleon systems. I review the results of χEFT power counting for charge and current operators up to [Formula: see text] relative to leading order, before showing that renormalization-group arguments imply that short-distance electromagnetic operators play a larger role than suggested by this standard counting. A detailed examination of χEFT's predictions for the electromagnetic form factors of deuterium and the trinucleons, and for the threshold captures np→dγ and nd→tγ, enables a critical appraisal of the theory's performance in these contexts. Recent χEFT calculations using the [Formula: see text] chiral perturbation theory (χPT) potential yielded both form factors that agree with experimental data for Q2<0.25 GeV2 and an excellent description of the challenging threshold captures. Short-distance M1 operators are essential to this success, and the addition of a short-distance part of the nucleon-nucleon charge operator produces precise predictions of the deuteron charge and quadrupole form factors in this kinematic domain.
Two-level convolution formula for nuclear structure function
Ma, Boqiang
1990-05-01
A two-level convolution formula for the nuclear structure function is derived in considering the nucleus as a composite system of baryon-mesons which are also composite systems of quark-gluons again. The results show that the European Muon Colaboration effect can not be explained by the nuclear effects as nucleon Fermi motion and nuclear binding contributions.
Del Dotto, Alessio; Salmè, Giovanni; Scopetta, Sergio
2016-01-01
Poincare' covariant definitions for the spin-dependent spectral function and for the momentum distributions within the light-front Hamiltonian dynamics are proposed for a three-fermion bound system, starting from the light-front wave function of the system. The adopted approach is based on the Bakamjian-Thomas construction of the Poincare' generators, that allows one to easily import the familiar and wide knowledge on the nuclear interaction into a light-front framework. The proposed formalism can find useful applications in refined nuclear calculations, like the ones needed for evaluating the EMC effect or the semi-inclusive deep inelastic cross sections with polarized nuclear targets, since remarkably the light-front unpolarized momentum distribution by definition fulfills both normalization and momentum sum rules. It is also shown a straightforward generalization of the definition of the light-front spectral function to an A-nucleon system.
Nuclear Structure Functions from Constituent Quark Model
Arash, F; Arash, Firooz; Atashbar-Tehrani, Shahin
1999-01-01
We have used the notion of the constituent quark model of nucleon, where a constituent quark carries its own internal structure, and applied it to determine nuclear structure functions ratios. It is found that the description of experimental data require the inclusion of strong shadowing effect for $x<0.01$. Using the idea of vector meson dominance model and other ingredients this effect is calculated in the context of the constituent quark model. It is rather striking that the constituent quark model, used here, gives a good account of the data for a wide range of atomic mass number from A=4 to A=204.
Rybczyński, Maciej
2011-01-01
We investigate the influence of the nucleon-nucleon collision profile (probability of interaction as a function of the nucleon-nucleon impact parameter) in the wounded nucleon model and its extensions on several observables measured in relativistic heavy-ion collisions. We find that the participant eccentricity coefficient, $\\epsilon^\\ast$, as well as the higher harmonic coefficients, $\\epsilon_n^\\ast$, are reduced by 10-20% for mid-peripheral collisions when the realistic (Gaussian) profile is used, as compared to the case with the commonly-used hard-sphere profile. Similarly, the multiplicity fluctuations, treated as the function of the number of wounded nucleons in one of the colliding nuclei, are reduced by 10-20%. This demonstrates that the Glauber Monte Carlo codes should necessarily use the realistic nucleon-nucleon collision profile in precision studies of these observables. The Gaussian collision profile is built-in in {\\tt GLISSANDO}.
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.
Spin and angular momentum in the nucleon
Energy Technology Data Exchange (ETDEWEB)
Franz Gross, Gilberto Ramalho, Teresa Pena
2012-05-01
Using the covariant spectator theory (CST), we present the results of a valence quark-diquark model calculation of the nucleon structure function f(x) measured in unpolarized deep inelastic scattering (DIS), and the structure functions g1(x) and g2(x) measured in DIS using polarized beams and targets. Parameters of the wave functions are adjusted to fit all the data. The fit fixes both the shape of the wave functions and the relative strength of each component. Two solutions are found that fit f(x) and g1(x), but only one of these gives a good description of g2(x). This fit requires the nucleon CST wave functions contain a large D-wave component (about 35%) and a small P-wave component (about 0.6%). The significance of these results is discussed.
Spin and angular momentum in the nucleon
Gross, Franz; Pena, M T
2012-01-01
Using the covariant spectator theory (CST), we present the results of a valence quark-diquark model calculation of the nucleon structure function f(x) measured in unpolarized deep inelastic scattering (DIS), and the structure functions g1(x) and g2(x) measured in DIS using polarized beams and targets. Parameters of the wave functions are adjusted to fit all the data. The fit fixes both the shape of the wave functions and the relative strength of each component. Two solutions are found that fit f(x) and g1(x), but only one of these gives a good description of g2(x). This fit requires the nucleon CST wave functions contain a large D-wave component (about 35%) and a small P-wave component (about 0.6%). The significance of these results is discussed.
Rowe, D. J.; McCoy, A. E.; Caprio, M. A.
2016-03-01
The nuclear collective models introduced by Bohr, Mottelson and Rainwater, together with the Mayer-Jensen shell model, have provided the central framework for the development of nuclear physics. This paper reviews the microscopic evolution of the collective models and their underlying foundations. In particular, it is shown that the Bohr-Mottelson models have expressions as macroscopic limits of microscopic models that have precisely defined expressions in many-nucleon quantum mechanics. Understanding collective models in this way is especially useful because it enables the analysis of nuclear properties in terms of them to be revisited and reassessed in the light of their microscopic foundations.
Alvioli, Massimiliano; Morita, Hiko
2016-01-01
The two-nucleon momentum distributions have been calculated for nuclei up to A=40 and various values of the relative and center-of-mass momenta and angle between them. For complex nuclei a parameter-free linked-cluster expansion, based upon a realistic local two-nucleon interaction of the Argonne family and variational wave function featuring central, tensor, spin and iso-spin correlations, has been used. The obtained results show that: 1) independently of the mass number A, at values of the relative momentum k_rel> 2 fm^{-1} the proton-neutron momentum distributions for back-to-back (BB) nucleons (K_cm=0) exhibit the factorization property n_A^{pn}(k_rel,K_cm=0)=C_A^{pn} n_D(k_rel) n_{cm}^{pn}(K_cm=0), where n_D is the deuteron momentum distribution, n_{cm}^{pn}(K_{cm}=0) the momentum distribution of the c.m. motion of the pair and C_A^{pn} the nuclear contact measuring the number of BB pn pairs with deuteron-like momenta; 2) the values of the proton-neutron nuclear contact C_A^{pn} are obtained in a model-i...
Momentum Distribution of a Fragment and Nucleon Removal Cross Section in the Reaction of Halo Nuclei
Institute of Scientific and Technical Information of China (English)
ZHAOYao-Lin; MAZhong-Yu; CHENBao-Qiu
2003-01-01
Recently the research on the halo structure of drip-line nuclei has shown some interesting properties of the existence of one or more halo nucleons. In the framework of few-body Glauber model, the momentum distribution of a fragment and nucleon removal cross section in the reaction of halo nuclei is presented and extended to nuclei having more than one halo nucleons. The reaction mechanism is treated with and without taking account of the final-state interaction. The wave function of removal halo nucleons in the continuum state is modified by imposing an orthogonal condition to the bound state. An analytical expression of the longitudinal momentum distribution of the fragment is derived when the bound state wave function of halo nucleons is taken as a Gaussian-type function. This is useful in the further investigation on the structure of halo nuclei.
pp Elastic Scattering in Near Forward Direction at LHC and Nucleon Structure
Islam, M M; Prokudin, A V
2005-01-01
We predict pp elastic differential cross section at LHC at the c.m. energy 14 TeV and momentum transfer range |t| = 0-10 GeV*2, which is planned to be measured by the TOTEM group. The field theory model underlying our phenomenological investigation describes the nucleon as a composite object with an outer cloud of quark-antiquark condensate, an inner core of topological baryonic charge, and a still smaller quark-bag of valence quarks. The model satisfactorily describes the asymptotic behavior of sigma-total(s) and rho(s) as well as the measured antiproton-proton elastic differential cross section at c.m. energies 546 GeV, 630 GeV, and 1.8 TeV. The large |t| elastic amplitude of the model incorporates the QCD hard pomeron (BFKL Pomeron plus next to leading order approximations), the perturbative dimensional counting behavior, and the confinement of valence quarks in a small region within the nucleon. Our predicted pp elastic differential cross section at LHC is compared with those of Bourrely et al. and Desgro...
First moment of the flavour octet nucleon parton distribution function using lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Constantinou, Martha; Hadjiyiannakou, Kyriakos; Koutsou, Giannis [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Dinter, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Institute for Advanced Study DIAS; Jansen, Karl [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Vaquero, Alejandro [INFN, Sezione di Milano-Bicocca, Milano (Italy); Collaboration: European Twisted Mass Collaboration
2015-03-15
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle {sup (8)}{sub μ{sup 2}=4} {sub GeV{sup 2}}. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed by S. Dinter et. al. (2012). We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)}) (with left angle x right angle {sup (3)} the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)})=0.39(1)(4).
Alpha Conjugate Neck Structures in the Collisions of 35 MeV/nucleon 40Ca with 40Ca
Schmidt, K; Kim, E J; Hagel, K; Barbui, M; Gauthier, J; Wuenschel, S; Giuliani, G; Rodrigues, M R D; Zheng, H; Huang, M; Blando, N; Bonasera, A; Wada, R; Botosso, C; Liu, G; Viesti, G; Moretto, S; Prete, G; Pesente, S; Fabris, D; Masri, Y El; Keutgen, T; Kolwaski, S; Kumar, A; Zhang, G; Natowitz, J B
2016-01-01
The de-excitation of alpha-conjugate nuclei produced in reactions of 35 MeV/nucleon 40Ca with 40Ca has been investigated. Particular emphasis is placed on examining the dynamics of collisions leading to projectile-like fragment exit channels. A general exploration of the reaction systematics reveals the binary dissipative character of the collisions and a hierarchy effect similar to that seen for heavier systems. Investigation of the subset of events characterized by a total alpha-conjugate mass (alpha particles plus alpha-conjugate fragments) equal to 40 and atomic number equal to 20 reveals a dominance of alpha-conjugate exit channels. The hierarchy effect for these channels leads to the production of alpha-clustered neck structures with potentially exotic geometries and properties.
EM vs Weak Structure Functions in DIS processes
Athar, M Sajjad; Simo, I Ruiz; Vacas, M J Vicente
2013-01-01
We obatin the ratio $F_i^A/F_i^{D}$(i=2,3, A=Be, C, Fe, Pb; D=Deuteron) in the case of weak and electromagnetic nuclear structure functions. For this, relativistic nuclear spectral function which incorporate the effects of Fermi motion, binding and nucleon correlations is used. We also consider the pion and rho meson cloud contributions and shadowing and antishadowing effects.
Feizi, H.; A. A., Rajabi; M. R., Shojaei
2012-07-01
In this work, the binding energy and wavefunctions of three-nucleon systems are obtained by using hyperspherical harmonic approach. We have used a mathematical modification method to obtain the eigenvalues and eigenfunctions of Schrödinger equation for three-nucleon systems in calculation. Next, we have used a simple approach to obtain the difference between binding energy of 3H and 3He where gives us mass splitting of three-nucleon systems. We have compared our results with the other works and experimental values.
R-ratios and moments of nuclear structure functions
Rinat, A S
2000-01-01
We study implications of a model, which links nuclear and nucleon structure functions. Computed Callen-Gross functions $\\kappa^A(x,Q^2)= 2xF_1^A(x,Q^2)/F_2^A(x,Q^2)$ appear for finite $Q^2$ to be close to their asymptotic value 1. Using those $\\kappa$, we compure $R$ ratios for $Q^2\\ge 5 GeV^2$. We review approximate methods in use for the extraction of $R$ from inclusive scattering and ENC data. Further we calcuate ratios of the moments of $F_k$ and find these to describe the data, in particular their $Q^2$ dependence. The above observables, as well as inclusive cross sections, are sensitive tests for the underlying relation between nucleonic and nuclear structure functions. In view of the overall agreement, we speculate that the above relation effectively circumvents a QCD calculation.
Comparing Some Nucleon-Nucleon Potentials
Naghdi, M
2013-01-01
The aim is to compare a few Nucleon-Nucleon (NN) potentials especially Reid68, Reid68-Day, Reid93, UrbanaV14, ArgonneV18, Nijmegen 93, Nijmegen I, Nijmegen II. Although these potentials have some likenesses and are almost phenomenological, they include in general different structures and its own characteristics. The potentials are constructed in a manner that fit the NN scattering data or phase shifts and are compared in this way. A high-quality scale of a potential is that it fits the data with $\\chi^{2}/N_{data} \\approx 1$, describes well deuteron properties or gives satisfactory results in nuclear structure calculations. However, these scales have some failures. Here, we first compare many potentials by confronting with data. Then, we try to compare the potential forms by considering the potential structures directly and therefore regarding their substantial basis somehow. On the other hand, since the potentials are written in different schema, it is necessary to write the potentials in a unique schema to ...
Statistical Error analysis of Nucleon-Nucleon phenomenological potentials
Perez, R Navarro; Arriola, E Ruiz
2014-01-01
Nucleon-Nucleon potentials are commonplace in nuclear physics and are determined from a finite number of experimental data with limited precision sampling the scattering process. We study the statistical assumptions implicit in the standard least squares fitting procedure and apply, along with more conventional tests, a tail sensitive quantile-quantile test as a simple and confident tool to verify the normality of residuals. We show that the fulfilment of normality tests is linked to a judicious and consistent selection of a nucleon-nucleon database. These considerations prove crucial to a proper statistical error analysis and uncertainty propagation. We illustrate these issues by analyzing about 8000 proton-proton and neutron-proton scattering published data. This enables the construction of potentials meeting all statistical requirements necessary for statistical uncertainty estimates in nuclear structure calculations.
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.
Nucleon-nucleon theory and phenomenology
Energy Technology Data Exchange (ETDEWEB)
Signell, P.
1981-03-01
This project involves five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the ..pi..N and ..pi pi.. physical regions of the N anti N ..-->.. ..pi pi.. amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 0-1200 MeV range that can be used by all nucleon-nucleon reseachers.
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.)
The Structure of the Nucleon and it's Excited States
Energy Technology Data Exchange (ETDEWEB)
None
1995-02-20
The past year has been an exciting and productive one for particle physics research at Abilene Christian University. The thrust of our experimental investigations is the study of the nucleon and its excited states. Laboratories where these investigations are presently being conducted are the AGS at Brookhaven, Fermilab and LAMPF. Some analysis of the data for experiments at the Petersburg Nuclear Physics Institute (Gatchina, Russia) is still in progress. Scheduling of activities at different laboratories inevitably leads to occasional conflicts. This likelihood is increased by the present budget uncertainties at the laboratories that make long-term scheduling difficult. For the most part, the investigators have been able to avoid such conflicts. Only one experiment received beam time in 1994 (E890 at the AGS). The situation for 1995-1996 also appears manageable at this point. E890 and another AGS experiment (E909) will run through May, 1995. El 178 at LAMPF is presently scheduled for August/September 1995. E866 at Fermilab is scheduled to start in Spring/Summer 1996. Undergraduate student involvement has been a key element in this research contract since its inception. Summer students participated at all of the above laboratories in 1994 and the same is planned in 1995. A transition to greater involvement by graduate students will provide cohesiveness to ACU involvement at a given laboratory and full-time on-site involvement in the longer running experiments at FNAL and BNL. Funds to support a full-time graduate student are requested this year. Finally, collaboration by Russian, Croatian and Bosnian scientists has proven to be mutually beneficial to these experimental programs and to the overall programs at the institutions involved. Past support has been augmented by other grants from government agencies and from the Research Council at Abilene Christian University. Additional funds are requested in this renewal to enable more programmatic support for these
Transversity of quarks in a nucleon
Indian Academy of Sciences (India)
K Bora; D K Choudhury
2003-11-01
The transversity distribution of quarks in a nucleon is one of the three fundamental distributions, that characterize nucleon’s properties in hard scattering processes at leading twist (twist 2). It measures the distribution of quark transverse spin in a nucleon polarized transverse to its (inﬁnite) momentum. It is a chiral-odd twist-two distribution function – gluons do not couple to it. Quarks in a nucleon/hadron are relativistically bound and transversity is a measure of the relativistic nature of bound quarks in a nucleon. In this work, we review some important aspects of this less familiar distribution function which has not been measured experimentally so far.
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.
Energy Technology Data Exchange (ETDEWEB)
Larochelle, Y.; Gingras, L.; Beaulieu, L.; Qian, X.; Saddiki, Z.; Djerroud, B.; Dore, D.; Laforest, R.; Roy, R.; Samri, M.; St-Pierre, C. [Laboratoire de Physique Nucleaire, Departement de Physique, Universite Laval, Quebec, G1K 7P4 (CANADA); Ball, G.C.; Bowman, D.R.; Galindo-Uribarri, A.; Hagberg, E.; Horn, D. [AECL, Chalk River Laboratories, Ontario, K0J 1J0 (CANADA); Lopez, J.A.; Robinson, T. [Department of Physics, University of Texas at El Paso, El Paso, Texas 79968-0515 (United States)
1997-04-01
The experimental signature of the formation of a necklike structure, with a velocity between that of the projectilelike emitter and that of the targetlike emitter, is investigated with the same beam and experimental setup for targets lighter and heavier than the projectile. The reactions are {sup 35}Cl on {sup 12}C and on {sup 197}Au at 43 MeV/nucleon. Particle velocity distributions are compared with two-source statistical simulations and the presence of a necklike structure is inferred from the data. In the second part of the paper, dynamical model simulations with the formation of a necklike structure are presented for the {sup 35}Cl+{sup 12}C system at 43 MeV/nucleon. {copyright} {ital 1997} {ital The American Physical Society}
Anomalous delta-type electric and magnetic two-nucleon interactions
Mandache, Nicolae Bogdan
2009-01-01
Anomalous delta-type interactions, of both electric and magnetic nature, are introduced between the overlapping peripheral structures of the nucleons, which may explain the spin-triplet deuteron state and the absence of other nucleon-nucleon bound states.
Somà, V.; Duguet, T.; Barbieri, C.
2011-12-01
An ab initio calculation scheme for finite nuclei based on self-consistent Green's functions in the Gorkov formalism is developed. It aims at describing properties of doubly magic and semimagic nuclei employing state-of-the-art microscopic nuclear interactions and explicitly treating pairing correlations through the breaking of U(1) symmetry associated with particle number conservation. The present paper introduces the formalism necessary to undertake applications at (self-consistent) second order using two-nucleon interactions in a detailed and self-contained fashion. First applications of such a scheme will be reported soon in a forthcoming publication. Future works will extend the present scheme to include three-nucleon interactions and implement more advanced truncation schemes.
Soma, V; Barbieri, C
2011-01-01
An ab-initio calculation scheme for finite nuclei based on self-consistent Green's functions in the Gorkov formalism is developed. It aims at describing properties of doubly-magic and semi-magic nuclei employing state-of-the-art microscopic nuclear interactions and explicitly treating pairing correlations through the breaking of U(1) symmetry associated with particle number conservation. The present paper introduces the formalism, necessary to undertake applications at (self-consistent) second-order using two-nucleon interactions, in a detailed and self-contained fashion. First applications of such a scheme will be reported soon in a forthcoming publication. Future works will extend the present scheme to include three-nucleon interactions and implement more advanced truncation schemes.
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.
Off-shell Corrections and Moments of the Deep Inelastic Nuclear Structure Functions
Cothran, C D; Liuti, S
1998-01-01
We present an improved method for handling off-shell effects in deep inelastic nuclear scattering. With a firm understanding of the effects of the nuclear wave function, including these off-shell corrections as well as binding and nucleon-nucleon correlations, we can begin to examine the role of QCD in nuclei through an analysis of the moments of the nuclear structure function. Our analysis is aimed at extracting the Q^2 dependence of the moments of the nucleon structure function by using the recent high x world Iron data and by properly removing nuclear effects from the perturbative contribution. In addition, we compare quantitatively the behavior of the extracted moments with a simple O(1/Q^2) phenomenological form and we determine the mass term for this parametrization.
Spin observables in nucleon-deuteron scattering and three-nucleon forces
Ishikawa, S; Iseri, Y
2002-01-01
Three-nucleon forces, which compose an up-to-date subject in few-nucleon systems, provide a good account of the triton binding energy and the cross section minimum in proton-deuteron elastic scattering, while do not succeed in explaining spin observables such as the nucleon and deuteron analyzing powers, suggesting serious defects in their spin dependence. We study the spin structure of nucleon-deuteron elastic amplitudes by decomposing them into spin-space tensors and examine effects of three-nucleon forces to each component of the amplitudes obtained by solving the Faddeev equation. Assuming that the spin-scalar amplitudes dominate the others, we derive simple expressions for spin observables in the nucleon-deuteron elastic scattering. The expressions suggest that a particular combination of spin observables in the scattering provides direct information of scalar, vector, or tensor component of the three-nucleon forces. These effects are numerically investigated by the Faddeev calculation.
Energy Technology Data Exchange (ETDEWEB)
Zheng, Xiaochao [Univ. of Virginia, Charlottesville, VA (United States). Jesse Beams Lab.
2016-03-10
spectrometer, called “SoLID”. Once built, SoLID can be used for other topics such as using PVDIS on a proton target to measure the valence quark distributions, using PVDIS on a polarized target to measure new electro-weak interference structure functions of the nucleon, and semi-inclusive deep inelastic scattering experiments. SoLID will greatly enhance the exploration potential of JLab. The proposed program will first focus on completion of the 6 GeV PVDIS experiment, its data analysis and publishing physics results. This 6 GeV experiment will explore whether precision PVDIS measurements are feasible, will set limits on the hadronic physics effects, and will improve our knowledge on the quark neutral weak couplings, optimally by a factor of six. Starting early 2010, efforts will be spent on preparation for the 11 GeV program, focusing on simulations of SoLID, optimization and construction of the SoLID detector package, and studies of the polarized ^{3}He target and its improvements. Funding support for the whole program is requested here.
Energy Technology Data Exchange (ETDEWEB)
Zheng, Xiaochao [Univ. of Virginia, Charlottesville, VA (United States). Jesse Beams Lab.
2016-03-10
spectrometer, called “SoLID”. Once built, SoLID can be used for other topics such as using PVDIS on a proton target to measure the valence quark distributions, using PVDIS on a polarized target to measure new electro-weak interference structure functions of the nucleon, and semi-inclusive deep inelastic scattering experiments. SoLID will greatly enhance the exploration potential of JLab. The proposed program will first focus on completion of the 6 GeV PVDIS experiment, its data analysis and publishing physics results. This 6 GeV experiment will explore whether precision PVDIS measurements are feasible, will set limits on the hadronic physics effects, and will improve our knowledge on the quark neutral weak couplings, optimally by a factor of six. Starting early 2010, efforts will be spent on preparation for the 11 GeV program, focusing on simulations of SoLID, optimization and construction of the SoLID detector package, and studies of the polarized ^{3}He target and its improvements. Funding support for the whole program is requested here.
Nucleon properties inside compressed nuclear matter
Rozynek, Jacek
2014-01-01
Our model calculations performed in the frame of the Bag Model (BM) approach show the modifications of nucleon mass, nucleon radius and a Parton Distribution Function (PDF) in Nuclear Matter (NM) above the saturation point. They originated from the pressure correction to the nucleon rest energy. Similar correction leads to conservation of a nuclear longitudinal momenta - essential in the explanation of the EMC effect at the saturation point of NM. Presented finite pressure corrections are generalization of the Hugenholtz-van Hove theorem valid for finite nucleon sizes inside NM.
Energy Technology Data Exchange (ETDEWEB)
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 proposal is that m...
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...
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)
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
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
Bianconi, Andrea; Tomasi-Gustafsson, Egle
2017-01-01
As is well known, spacelike proton form factors expressed in the Breit frame may be interpreted as the Fourier transform of static space distributions of electric charge and current. In particular, the electric form factor is simply the Fourier transform of the charge distribution F (q ) =∫ei q ⃗.r ⃗ρ (r ) d3r . We do not have an intuitive interpretation of the same level of simplicity for the proton timelike form factor appearing in the reactions e+e-↔p ¯p . However, one may suggest that, in the center-of-mass frame, where qμxμ=q t , a timelike electric form factor is the Fourier transform F (q ) =∫ei q tR (t ) d t of a function R (t ) expressing how the electric properties of the forming (or annihilating) proton-antiproton pair evolve in time. Here we analyze in depth this idea and show that the functions ρ (r ) and R (t ) can be formally written as the time and space integrals of a unique correlation function depending on both time and space coordinates.
Bianconi, Andrea
2016-01-01
As well known, spacelike proton form factors expressed in the Breit frame may be interpreted as the Fourier transform of static space distributions of electric charge and current. In particular, the electric form factor is simply the Fourier transform of the charge distribution $F(q)=\\int e^{i\\vec q \\cdot \\vec r} \\rho(r)d^3r$. We don't have an intuitive interpretation of the same level of simplicity for the proton timelike form factor appearing in the reactions $e^+e^-\\leftrightarrow \\bar{p}p$. However, one may suggest that in the center of mass (CM) frame, where $q_\\mu x^\\mu =qt$, a timelike electric form factor is the Fourier transform $F(q) =\\int e^{iqt} R(t)dt$ of a function $R(t)$ expressing how the electric properties of the forming (or annihilating) proton-antiproton pair evolve in time. Here we analyze in depth this idea, show that the functions $\\rho(r)$ and $R(t)$ can be formally written as the time and space integrals of a unique correlation function depending on both time and space coordinates.
Spin-orbit correlations in the nucleon
Lorcé, Cédric
2014-01-01
We investigate the correlations between the quark spin and orbital angular momentum inside the nucleon. Similarly to the Ji relation, we show that these correlations can be expressed in terms of specific moments of measurable parton distributions. This provides a whole new piece of information about the partonic structure of the nucleon.
Silva, Antonio; Kim, Hyun-Chul
2013-01-01
We investigate the flavor decomposition of the electromagnetic form factors of the nucleon, based on the chiral quark-soliton model with symmetry-conserving quantization. We consider the rotational 1/N_c and linear strange-quark mass (m_s) corrections. To extend the results to higher momentum transfer, we take into account the kinematical relativistic effects. We discuss the results of the flavor-decomposed electromagnetic form factors in comparison with the recent experimental data. In order to see the effects of the strange quark, we compare the SU(3) results with those of SU(2). We finally discuss the transverse charge densities for both unpolarized and polarized nucleons.
Nucleon-Nucleon Scattering in a Three Dimensional Approach
Fachruddin, I; Glöckle, W; Elster, Ch.
2000-01-01
The nucleon-nucleon (NN) t-matrix is calculated directly as function of two vector momenta for different realistic NN potentials. To facilitate this a formalism is developed for solving the two-nucleon Lippmann-Schwinger equation in momentum space without employing a partial wave decomposition. The total spin is treated in a helicity representation. Two different realistic NN interactions, one defined in momentum space and one in coordinate space, are presented in a form suited for this formulation. The angular and momentum dependence of the full amplitude is studied and displayed. A partial wave decomposition of the full amplitude it carried out to compare the presented results with the well known phase shifts provided by those interactions.
Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon
Kanazawa, K; Metz, A; Pasquini, B; Schlegel, M
2014-01-01
Generalized transverse-momentum dependent parton distributions (GTMDs) encode the most general parton structure of hadrons. Here we focus on two twist-2 GTMDs which are denoted by $F_{1,4}$ and $G_{1,1}$ in parts of the literature. As already shown previously, both GTMDs have a close relation to orbital angular momentum of partons inside a hadron. However, recently even the mere existence of $F_{1,4}$ and $G_{1,1}$ has been doubted. We explain why this claim does not hold. We support our model-independent considerations by calculating the two GTMDs in the scalar diquark model and in the quark-target model, where we also explicitly check the relation to orbital angular momentum. In addition, we compute $F_{1,4}$ and $G_{1,1}$ at large transverse momentum in perturbative Quantum Chromodynamics and show that they are nonzero.
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.
Directory of Open Access Journals (Sweden)
F Zolfagharpour
2012-03-01
Full Text Available In this paper, we calculate nuclear structure function and EMC effect of 40Ca and 56Fe nuclei. To achive the goals, we consider Fermi motion and binding energy contrbiution in the harmonic oscillator model. In this model, harmonic oscillator parameter ħω related to shells root mean square radius and for free nucleon structure functions, is obtained from GRV’s free nucleon structure functions. Then, we calculate differential cross section of lepton scattering from those nuclei at the E=4.8 GeV and E=4.032 GeV. The obtained results show good agreement with available experimental data.
Burkert, Volker D
2016-01-01
Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and $\\Delta$ states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger Equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of $Q^2 > 1.5GeV^2$. In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degre...
Burkert, Volker D.
2016-10-01
Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and Δ states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of Q^2 > 1.5 GeV^2. In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degrees of freedom underlying the excited states and their dependence on the distance scale probed.
Avakian, H; Hasch, D; Schweitzer, P
2012-01-01
The three-dimensional nucleon structure is central to many theoretical and experimental activities, and research in this field has seen many advances in the last two decades, addressing fundamental questions such as the orbital motion of quarks and gluons inside the nucleons, their spatial distribution, and the correlation between spin and intrinsic motion. A real three-dimensional imaging of the nucleon as a composite object, both in momentum and coordinate space, is slowly emerging. This book presents lectures and seminars from the Enrico Fermi School: Three-Dimensional Partonic Structure of the Nucleon, held in Varenna, Italy, in June and July 2011. The topics covered include: partonic distributions, fragmentation functions and factorization in QCD; theory of transverse momentum dependent partonic distributions (TMDs) and generalized partonic distributions (GPDs); experimental methods in studies of hard scattering processes; extraction of TMDs and GPDs from data; analysis tools for azimuthal asymmetries; ...
Nuclear medium modification of the F2 structure function
Athar, M Sajjad; Vacas, M J Vicente
2009-01-01
We study the nuclear effects in the electromagnetic structure function $F_{2}(x, Q^2)$ in nuclei in the deep inelastic lepton nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. The ratios $R_{F2}^A(x,Q^2)=\\frac{2F_2^A(x,Q^2)}{AF_{2}^{Deut}(x,Q^2)}$ are obtained and compared with the recent JLAB results for light nuclei that show a non trivial A dependence.
Quark sea asymmetry of the nucleon
Mírez, Carlos; Tomio, Lauro; Trevisan, L. A.; Frederico, T.
2010-02-01
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.
DEFF Research Database (Denmark)
Sinden, Richard R.; E. Pearson, Christopher; N. Potaman, Vladimir
1998-01-01
This chapter discusses the structure and function of DNA. DNA occupies a critical role in cells, because it is the source of all intrinsic genetic information. Chemically, DNA is a very stable molecule, a characteristic important for a macromolecule that may have to persist in an intact form...... 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...
The Nucleon-Nucleon Interaction in a Chiral Constituent Quark Model
Stancu, F; Glozman, L Ya; Stancu, Fl.
1997-01-01
We study the short-range nucleon-nucleon interaction in a chiral constituent quark model by diagonalizing a Hamiltonian comprising a linear confinement and a Goldstone boson exchange interaction between quarks. The six-quark harmonic oscillator basis contains up to two excitation quanta. We show that the highly dominant configuration is $\\mid s^4p^2[42]_O [51]_{FS}>$ due to its specific flavour-spin symmetry. Using the Born-Oppenheimer approximation we find a strong effective repulsion at zero separation between nucleons in both $^3S_1$ and $^1S_0$ channels. The symmetry structure of the highly dominant configuration implies the existence of a node in the S-wave relative motion wave function at short distances. The amplitude of the oscillation of the wave function at short range will be however strongly suppressed. We discuss the mechanism leading to the effective short-range repulsion within the chiral constituent quark model as compared to that related with the one-gluon exchange interaction.
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...
Nucleon propagation through nuclear matter in chiral effective field theory
Mallik, S; Mishra, Hiranmaya
2007-01-01
We treat the propagation of nucleon in nuclear matter by evaluating the ensemble average of the two-point function of nucleon currents in the framework of the chiral effective field theory. We first derive the effective parameters of nucleon to one loop. The resulting formula for the effective mass was known previously and gives an absurd value at normal nuclear density. We then modify it following Weinberg's method for the two-nucleon system in the effective theory. Our results for the effective mass and the width of nucleon are compared with those in the literature.
Nucleon propagation through nuclear matter in chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Mallik, S. [Saha Institute of Nuclear Physics, Kolkata (India); Mishra, H. [Physical Research Laboratory, Theory Divison, Ahmedabad (India)
2007-05-15
We treat the propagation of a nucleon in nuclear matter by evaluating the ensemble average of the two-point function of the nucleon currents in the framework of chiral effective field theory. We first derive the effective parameters of the nucleon to one loop. The resulting formula for the effective mass has been known since before and gives an absurd value at normal nuclear density. We then modify it following Weinberg's method for the two-nucleon system in the effective theory. Our results for the effective mass and the width of the nucleon are compared with those in the literature. (orig.)
Nucleon propagation through nuclear matter in chiral effective field theory
Mallik, S.; Mishra, H.
2007-05-01
We treat the propagation of a nucleon in nuclear matter by evaluating the ensemble average of the two-point function of the nucleon currents in the framework of chiral effective field theory. We first derive the effective parameters of the nucleon to one loop. The resulting formula for the effective mass has been known since before and gives an absurd value at normal nuclear density. We then modify it following Weinberg’s method for the two-nucleon system in the effective theory. Our results for the effective mass and the width of the nucleon are compared with those in the literature.
Ossmann, J; Schweitzer, P; Urbano, D; Göke, K
2004-01-01
The unpolarized spin-flip isoscalar generalized parton distribution function (E^u+E^d)(x,xi,t) is studied in the large-Nc limit at a low normalization point in the framework of the chiral quark-soliton model. This is the first study of generalized parton distribution functions in this model, which appear only at the subleading order in the large-Nc limit. Particular emphasis is put therefore on the demonstration of the theoretical consistency of the approach. The forward limit of (E^u+E^d)(x,xi,t) of which only the first moment -- the anomalous isoscalar magnetic moment of the nucleon -- is known phenomenologically, is computed numerically. Observables sensitive to (E^u+E^d)(x,xi,t) are discussed.
Deuteron Spin Structure Functions at Small Bjorken-x
Edelmann, J; Weise, W
1998-01-01
We investigate polarized deuteron structure functions at small values of the Bjorken variable, x < 0.1. In this region contributions from the coherent interaction of diffractively excited hadronic states with both nucleons become important. A proper treatment of this process requires an extension of the Glauber-Gribov multiple scattering theory to include spin degrees of freedom. In the kinematic domain of current fixed target experiments we observe that shadowing effects in g_1^d are approximately a factor 2-3 larger than for the unpolarized structure function F_2^d. Furthermore the tensor structure function b_1 is found to be surprisingly large at x < 0.1 due to coherent double scattering contributions.
Orbital angular momentum in the nucleons
Lorcé, Cédric
2014-01-01
In the last decade, it has been realized that the orbital angular momentum of partons inside the nucleon plays a major role. It contributes significantly to nucleon properties and is at the origin of many asymmetries observed in spin physics. It is therefore of paramount importance to determine this quantity if we want to understand the nucleon internal structure and experimental observables. This triggered numerous discussions and controversies about the proper definition of orbital angular momentum and its extraction from experimental data. We summarize the present situation and discuss recent developments in this field.
Time-reversal-invariance-violating nucleon-nucleon potential in the 1/N_c expansion
Samart, Daris; Schindler, Matthias R; Phillips, Daniel R
2016-01-01
We apply the large-$N_c$ expansion to the time-reversal-invariance-violating (TV) nucleon-nucleon potential. The operator structures contributing to next-to-next-to-leading order in the large-$N_c$ counting are constructed. For the TV and parity-violating case we find a single operator structure at leading order. The TV but parity-conserving potential contains two leading-order terms, which however are suppressed by 1/$N_c$ compared to the parity-violating potential. Comparison with phenomenological potentials, including the chiral EFT potential in the TV parity-violating case, leads to large-$N_c$ scaling relations for TV meson-nucleon and nucleon-nucleon couplings.
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...
Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order
Epelbaum, E; Meißner, U -G
2014-01-01
We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362], [D.R. Entem, R. Machleidt, Phys. Rev. C68 (2003) 041001] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\\ss}ner, Nucl. Phys. A747 (2005) 362] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c_i and d_i determined from pion-nucleon scattering without any fine tuning. We discuss in detail t...
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.
Hidden Color and the $b_1$ structure function of the deuteron
Miller, Gerald A
2014-01-01
The $b_1$ structure function is an observable feature of a spin-1 system sensitive to non-nucleonic components of the target nuclear wave function. A simple model for hidden-color, six-quark configurations is proposed and found to give substantial contributions for values of $ x>0.2$. Good agreement with Hermes data is obtained. Predictions are made for an upcoming JLab experiment.
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.
The isospin structure of photoproduction of πη pairs from the nucleon in the threshold region
Directory of Open Access Journals (Sweden)
A. Käser
2015-09-01
Full Text Available Photoproduction of πη-pairs from nucleons has been investigated from threshold up to incident photon energies of ≈ 1.4 GeV. The quasi-free reactions γp→pπ0η, γn→nπ0η, γp→nπ+η, and γn→pπ−η 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 γp→nπ+η reaction was measured for the first time. For the π0η final state coherent production via the γd→dπ0η reaction was also investigated. The experiments were performed at the tagged photon beam of the Mainz MAMI accelerator using an almost 4π coverage electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The total cross sections for the four different final states obey the relation σ(pπ0η≈σ(nπ0η≈2σ(pπ−η≈2σ(nπ+η as expected for a dominant contribution from a Δ⋆→ηΔ(1232→πηN reaction chain, which is also supported by the shapes of the invariant-mass distributions of nucleon–meson and π–η pairs. The experimental results are compared to the predictions from an isobar reaction model.
Tvaskis, V; Niculescu, I; Abbott, D; Adams, G S; Afanasev, A; Ahmidouch, A; Angelescu, T; Arrington, J; Asaturyan, R; Avery, S; Baker, O K; Benmouna, N; Berman, B L; Biselli, A; Blok, H P; Boeglin, W U; Bosted, P E; Brash, E; Breuer, H; Chang, G; Chant, N; Christy, M E; Connell, S H; Dalton, M M; Danagoulian, S; Day, D; Dodario, T; Dunne, J A; Dutta, D; Khayari, N El; Ent, R; Fenker, H C; Frolov, V V; Gaskell, D; Garrow, K; Gilman, R; Gueye, P; Hafidi, K; Hinton, W; Holt, R J; Horn, T; Huber, G M; Jackson, H; Jiang, X; Jones, M K; Joo, K; Kelly, J J; Keppel, C E; Kuhn, J; Kinney, E; Klein, A; Kubarovsky, V; Liang, M; Liang, Y; Lolos, G; Lung, A; Mack, D; Malace, S; Markowitz, P; Mbianda, G; McGrath, E; Mckee, D; McKee, P; Meekins, D G; Mkrtchyan, H; Moziak, B; Napolitano, J; Navasardyan, T; Niculescu, G; Nozar, M; Ostapenko, T; Papandreou, Z; Potterveld, D; Reimer, P E; Reinhold, J; Roche, J; Rock, S E; Schulte, E; Segbefia, E; Smith, C; Smith, G R; Stoler, P; Tadevosyan, V; Tang, L; Telfeyan, J; Todor, L; Ungaro, M; Uzzle, A; Vidakovic, S; Villano, A; Vulcan, W F; Wang, M; Warren, G; Wesselmann, F; Wojtsekhowski, B; Wood, S A; Xu, C; Yan, C; Yuan, L; Zheng, X; Zihlmann, B; Zhu, H
2016-01-01
Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the quark dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available for the longitudinal structure function in particular. Here we present separated structure functions for hydrogen and deuterium at low four--momentum transfer squared, Q^2< 1 GeV^2, and compare these with parton distribution parameterizations and a k_T factorization approach. While differences are found, the parameterizations generally agree with the data even at the very low Q^2 scale of the data. The deuterium data show a smaller longitudinal structure function, and smaller ratio of longitudinal to transverse cross section R, than the proton. This suggests either an unexpected difference in R for the proton and neutron or a suppression of the gluonic distribution in nuclei.
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.)
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.
McDonald, J.; collaboration, for the NuTeV
2001-01-01
Preliminary results for the neutrino-nucleon differential cross section from the NuTeV experiment are presented. The extraction of the differential cross section from NuTeV is discussed and the structure functions $F_2$ and $\\Delta xF_3$ are presented. Comparisons are made with CCFR results.
Korover, I.; Muangma, N.; Hen, O.; Shneor, R.; Sulkosky, V.; Kelleher, A.; Gilad, S.; Higinbotham, D. W.; Piasetzky, E.; Watson, J. W.; Wood, S. A.; 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. 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, J.-O.; Hashemi Shabestari, M.; 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.; Marti Jimenez-Arguello, A.; Meekins, D.; Meziani, Z.; Michaels, R.; Mihovilovic, M.; Monaghan, P.; Munoz Camacho, C.; Norum, B.; Nuruzzaman, Pan, K.; Phillips, S.; Pomerantz, I.; Posik, M.; Punjabi, V.; Qian, X.; Qiang, Y.; Qiu, X.; Rakhman, A.; 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.; Jefferson Lab Hall A Collaboration
2014-07-01
We studied simultaneously the He4(e ,e'p), He4(e ,e'pp), and He4(e ,e'pn) reactions at Q2=2(GeV/c)2 and xB>1, for an (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 (NN) force is expected to change from predominantly tensor to repulsive. The abundance of neutron-proton pairs 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. Our data are compared with calculations of two-nucleon momentum distributions in He4 and discussed in the context of probing the elusive repulsive component of the NN force.
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}.
Nuclear Dependence in Weak Structure Functions and the Determination of Weak Mixing Angle
Athar, M Sajjad; Simo, I Ruiz; Vacas, M J Vicente
2013-01-01
We have studied nuclear medium effects in the weak structure functions $F^A_2(x)$ and $F^A_3(x)$ and in the extraction of weak mixing angle using Paschos Wolfenstein(PW) relation. We have modified the PW relation for nonisoscalar nuclear target. We have incorporated the medium effects like Pauli blocking, Fermi motion, nuclear binding energy, nucleon correlations, pion $\\&$ rho cloud contributions, and shadowing and antishadowing effects.
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.
Accardi, Alberto
2016-01-01
I review recent progress in the extraction of unpolarized parton distributions in the proton and in nuclei from a unified point of view that highlights how the interplay between high energy particle physics and lower energy nuclear physics can be of mutual benefit to either field. Areas of overlap range from the search for physics beyond the standard model at the LHC, to the study of the non perturbative structure of nucleons and the emergence of nuclei from quark and gluon degrees of freedom, to the interaction of colored probes in a cold nuclear medium.
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
The Pion-Cloud Contribution to the Electromagnetic Nucleon Form Factors
Directory of Open Access Journals (Sweden)
Kupelwieser Daniel
2016-01-01
Full Text Available We study the electromagnetic structure of the nucleon within a hybrid constituent-quark model that comprises, in addition to the 3q valence component, also a 3q+π non-valence component. To this aim we employ a Poincaré-invariant multichannel formulation based on the point-form of relativistic quantum mechanics. With a simple 3-quark wave function for the bare nucleon, i.e. the 3q-component, we obtain reasonable results for the nucleon form factors and predict the meson-cloud contribution to be significant only below Q2 ≲ 0:5 GeV2 amounting to about 10% for Q2 → 0, in accordance with the findings of other authors.
Structure functions at large x
Zhang, Z
2002-01-01
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.
A Covariant model for the nucleon and the $\\Delta$
Ramalho, G; Gross, Franz
2008-01-01
The covariant spectator formalism is used to model the nucleon and the $\\Delta$(1232) as a system of three constituent quarks with their own electromagnetic structure. The definition of the ``fixed-axis'' polarization states for the diquark emitted from the initial state vertex and absorbed into the final state vertex is discussed. The helicity sum over those states is evaluated and seen to be covariant. Using this approach, all four electromagnetic form factors of the nucleon, together with the {\\it magnetic} form factor, $G_M^*$, for the $\\gamma N \\to \\Delta$ transition, can be described using manifestly covariant nucleon and $\\Delta$ wave functions with {\\it zero} orbital angular momentum $L$, but a successful description of $G_M^*$ near $Q^2=0$ requires the addition of a pion cloud term not included in the class of valence quark models considered here. We also show that the pure $S$-wave model gives electric, $G_E^*$, and coulomb, $G^*_C$, transition form factors that are identically zero, showing that th...
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.
Structural Chemistry of Functional Materials
Institute of Scientific and Technical Information of China (English)
2011-01-01
@@ This innovative research group on structural chemistry of functional materials was approved by NSFC in 2005.Headed by Prof.HONG Maochun, the team consists of several young research scientists from the CAS Fujian Institute of Research on the Structures of Matter, including Profs CAO Rong, LU Canzhong, GUO Guocong, CHEN Zhongning, MAO Jianggao Mao and CHEN Ling.
Leading order covariant chiral nucleon-nucleon interaction
Ren, Xiu-Lei; Geng, Li-Sheng; Long, Bing-Wei; Ring, Peter; Meng, Jie
2016-01-01
Motivated by the successes of relativistic theories in studies of atomic/molecular and nuclear systems and the strong need for a covariant chiral force in relativistic nuclear structure studies, we develop a new covariant scheme to construct the nucleon-nucleon interaction in the framework of chiral effective field theory. The chiral interaction is formulated up to leading order with a covariant power counting and a Lorentz invariant chiral Lagrangian. We find that the covariant scheme induces all the six invariant spin operators needed to describe the nuclear force, which are also helpful to achieve cutoff independence for certain partial waves. A detailed investigation of the partial wave potentials shows a better description of the scattering phase shifts with low angular momenta than the leading order Weinberg approach. Particularly, the description of the $^1S_0$, $^3P_0$, and $^1P_1$ partial waves is similar to that of the next-to-leading order Weinberg approach. Our study shows that the relativistic fr...
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.
Polarized light ions and spectator nucleon tagging at EIC
Energy Technology Data Exchange (ETDEWEB)
Guzey, Vadim [Petersburg Nuclear Physics Institute, Gatchina, 188300, Russia; Higinbotham, Dougas W. [JLAB; Hyde, Charles [Old Dominion University, Norfolk, VA 23529, USA; Nadel-Turonski, Pawel A. [JLAB; Park, Kijun [Old Dominion University, Norfolk, VA 23529, USA; Sargsian, Misak M. [Florida International University, Miami, FL 33199, USA; Strikman, Mark [Pennsylvania State University, University Park, PA 16802, USA; Weiss, Christian [JLAB
2014-10-01
The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x ll 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < p(R) < several 100MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.
Structure functions and parton distributions
Energy Technology Data Exchange (ETDEWEB)
Martin, A.D.; Stirling, W.J. [Univ. of Durham (United Kingdom); Roberts, R.G. [Rutherford Appleton Lab., Chilton, Didcot (United Kingdom)
1995-07-01
The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.
Proton structure functions at HERA
Stella, Bruno
2001-10-01
The electron-proton collider HERA, like an electron-mycroscope, explores the structure of the proton down to 10-16 cm and up to the situation of very high parton densities. The proton energy was upgraded from 820 to 920 GeV in the Fall of '98 and the luminosity has also substantially improved, with another factor of 3 upgrade expected to follow this year. Inclusive proton structure functions have been studied with incident e+ and e- of 27 GeV in the neutral (NC) and charged (CC) current interactions as functions of the squared four-momentum transfer, Q2, and of the fractional proton momentum carried by partons, x. The structure function F2, as well as the γ-Z0 interference term xF3, have been measured in a range of Q2 and 1/x that extends by orders of magnitude that reached by fixed target experiments. The DGLAP evolution equations [1] allow for a perturbative NLO QCD fit of the measured non-perturbative structure functions in the available kinematic range: αS and the gluon density at low x are fitted at the same time with good precision. The longitudinal structure function, FL, can be determined within the DGLAP formalism. With CC, the electroweak unification has been tested; at high x, a first flavor decomposition of the light quarks is achieved. The contribution to F2 of the charm quark has been measured and results to be relevant. Bounds on the radius of quarks and on compositeness are derived from the data at the highest Q2, 100
A study of nuclear effect in $F_3$ structure function in the deep inelastic $\
Athar, M Sajjad; Singh, S K; Vacas, M J Vicente
2009-01-01
We study nuclear effect in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by taking into account Fermi motion, binding, target mass correction, shadowing and anti-shadowing corrections. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. Results for $F^A_3(x)$ have been compared with the results reported at NuTeV and also with some of the older experiments reported in the literature.
Few-nucleon systems with state-of-the-art chiral nucleon-nucleon forces
Binder, S; Epelbaum, E; Furnstahl, R J; Golak, J; Hebeler, K; Kamada, H; Krebs, H; Langhammer, J; Liebig, S; Maris, P; Meißner, U -G; Minossi, D; Nogga, A; Potter, H; Roth, R; Skibinski, R; Topolnicki, K; Vary, J P; Witala, H
2015-01-01
We apply improved nucleon-nucleon potentials up to fifth order in chiral effective field theory, along with a new analysis of the theoretical truncation errors, to study nucleon-deuteron (Nd) scattering and selected low-energy observables in 3H, 4He, and 6Li. Calculations beyond second order differ from experiment well outside the range of quantified uncertainties, providing truly unambiguous evidence for missing three-nucleon forces within the employed framework. The sizes of the required three-nucleon force contributions agree well with expectations based on Weinberg's power counting. We identify the energy range in elastic Nd scattering best suited to study three-nucleon force effects and estimate the achievable accuracy of theoretical predictions for various observables.
Maekawa, Nobuhiro; Muramatsu, Yu
2017-04-01
Recent discovery of neutrino large mixings implies the large mixings in the diagonalizing matrices of 5 bar fields in SU (5) grand unified theory (GUT), while the diagonalizing matrices of 10 fields of SU (5) are expected to have small mixings like Cabibbo-Kobayashi-Maskawa matrix. We calculate the predictions of flavor changing nucleon decays (FCND) in SU (5), SO (10), and E6 GUT models which have the above features for mixings. We found that FCND can be the main decay mode and play an important role to test GUT models.
Estimates of the Nucleon Tensor Charge
Gamberg, L P; Gamberg, Leonard; Goldstein, Gary R.
2001-01-01
Like the axial vector charges, defined from the forward nucleon matrix element of the axial vector current on the light cone, the nucleon tensor charge, defined from the corresponding matrix element of the tensor current, is essential for characterizing the momentum and spin structure of the nucleon. Because there must be a helicity flip of the struck quark in order to probe the transverse spin polarization of the nucleon, the transversity distribution (and thus the tensor charge) decouples at leading twist in deep inelastic scattering, although no such suppression appears in Drell-Yan processes. This makes the tensor charge difficult to measure and its non-conservation makes its prediction model dependent. We present a different approach. Exploiting an approximate SU(6)xO(3) symmetric mass degeneracy of the light axial vector mesons (a1(1260), b1(1235) and h1(1170)) and using pole dominance, we calculate the tensor charge. The result is simple in form and depends on the decay constants of the axial vector me...
[Protein phosphatases: structure and function].
Bulanova, E G; Budagian, V M
1994-01-01
The process of protein and enzyme systems phosphorylation is necessary for cell growth, differentiation and preparation for division and mitosis. The conformation changes of protein as a result of phosphorylation lead to increased enzyme activity and enhanced affinity to substrates. A large group of enzymes--protein kinases--is responsible for phosphorylation process in cell, which are divided into tyrosine- and serine-threonine-kinases depending on their ability to phosphorylate appropriate amino acid residues. In this review has been considered the functional importance and structure of protein phosphatases--enzymes, which are functional antagonists of protein kinases.
Wang, D; Subedi, R; Deng, X; Ahmed, Z; Allada, K; Aniol, K A; Armstrong, D S; Arrington, J; Bellini, V; Beminiwattha, R; Benesch, J; Benmokhtar, F; Camsonne, A; Canan, M; Cates, G D; Chen, J -P; Chudakov, E; Cisbani, E; Dalton, M M; de Jager, C W; De Leo, R; Deconinck, W; Deur, A; Dutta, C; Fassi, L El; Flay, D; Franklin, G B; Friend, M; Frullani, S; Garibaldi, F; Giusa, A; Glamazdin, A; Golge, S; Grimm, K; Hafidi, K; Hansen, O; Higinbotham, D W; Holmes, R; Holmstrom, T; Holt, R J; Huang, J; Hyde, C E; Jen, C M; Jones, D; Kang, H; King, P; Kowalski, S; Kumar, K S; Lee, J H; LeRose, J J; Liyanage, N; Long, E; McNulty, D; Margaziotis, D J; Meddi, F; Meekins, D G; Mercado, L; Meziani, Z -E; Michaels, R; Mihovilovic, M; Muangma, N; Myers, K E; Nanda, S; Narayan, A; Nelyubin, V; Nuruzzaman,; Oh, Y; Parno, D; Paschke, K D; Phillips, S K; Qian, X; Qiang, Y; Quinn, B; Rakhman, A; Reimer, P E; Rider, K; Riordan, S; Roche, J; Rubin, J; Russo, G; Saenboonruang, K; Saha, A; Sawatzky, B; Shahinyan, A; Silwal, R; Sirca, S; Souder, P A; Suleiman, R; Sulkosky, V; Sutera, C M; Tobias, W A; Waidyawansa, B; Wojtsekhowski, B; Ye, L; Zhao, B; Zheng, X
2013-01-01
We report on parity-violating asymmetries in the nucleon resonance region measured using $5 - 6$ GeV longitudinally polarized electrons scattering off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the $\\Delta(1232)$, and provide a verification of quark-hadron duality in the nucleon electroweak $\\gamma Z$ interference structure functions at the 10-15% level. The results are of particular interest to models relevant for calculating the $\\gamma Z$ box-diagram corrections to elastic parity-violating electron scattering measurements.
Structure and Function of Glucansucrases
Dijkstra, B. W.; Vujičić-Žagar, A.
2008-03-01
Glucansucrases are relatively large (~160 kDa) extracellular enzymes produced by lactic acid bacteria. Using sucrose as a substrate they synthesize high molecular mass glucose polymers, called α-glucans, which allow the bacteria to adhere to surfaces and create a biofilm. The glucan polymers are of importance for the food and dairy industry as thickening and jellying agents. An overview is given of the current insights into the structure and functioning of these and related enzymes.
Bialas, A; Royon, C; Royon, Ch.
1998-01-01
It is argued that the QCD dipole picture allows to build an unified theoretical description -based on BFKL dynamics- of the total and diffractive nucleon structure functions. This description is in qualitative agreement with the present collection of data obtained by the H1 collaboration. More precise theoretical estimates, in particular the determination of the normalizations and proton transverse momentum behaviour of the diffractive components, are shown to be required in order to reach definite conclusions.
Dimensional versus cut-off renormalization and the nucleon-nucleon interaction
Ghosh, A; Talukdar, B; Ghosh, Angsula; Adhikari, Sadhan K.
1998-01-01
The role of dimensional regularization is discussed and compared with that of cut-off regularization in some quantum mechanical problems with ultraviolet divergence in two and three dimensions with special emphasis on the nucleon-nucleon interaction. Both types of renormalizations are performed for attractive divergent one- and two-term separable potentials, a divergent tensor potential, and the sum of a delta function and its derivatives. We allow energy-dependent couplings, and determine the form that these couplings should take if equivalence between the two regularization schemes is to be enforced. We also perform renormalization of an attractive separable potential superposed on an analytic divergent potential.
Dimensional versus cut-off renormalization and the nucleon-nucleon interaction
Ghosh, Angsula; Adhikari, Sadhan K.; Talukdar, B.
1998-10-01
The role of dimensional regularization is discussed and compared with that of cut-off regularization in some quantum mechanical problems with ultraviolet divergence in two and three dimensions with special emphasis on the nucleon-nucleon interaction. Both types of renormalizations are performed for attractive divergent one- and two-term separable potentials, a divergent tensor potential, and the sum of a delta function and its derivatives. We allow energy-dependent couplings, and determine the form that these couplings should take if equivalence between the two regularization schemes is to be enforced. We also perform renormalization of an attractive separable potential superposed on an analytic divergent potential.
Three pion nucleon coupling constants
Arriola, E Ruiz; Perez, R Navarro
2016-01-01
There exist four pion nucleon coupling constants, $f_{\\pi^0, pp}$, $-f_{\\pi^0, nn}$, $f_{\\pi^+, pn} /\\sqrt{2}$ and $ f_{\\pi^-, np} /\\sqrt{2}$ which coincide when up and down quark masses are identical and the electron charge is zero. While there is no reason why the pion-nucleon-nucleon coupling constants should be identical in the real world, one expects that the small differences might be pinned down from a sufficiently large number of independent and mutually consistent data. Our discussion provides a rationale for our recent determination $$f_p^2 = 0.0759(4) \\, , \\quad f_{0}^2 = 0.079(1) \\,, \\quad f_{c}^2 = 0.0763(6) \\, , $$ based on a partial wave analysis of the $3\\sigma$ self-consistent nucleon-nucleon Granada-2013 database comprising 6713 published data in the period 1950-2013.
Modarres, M.; Younesizadeh, Y.
2012-05-01
In this work, the two-nucleon spectral functions (TNSFs) are defined in terms of the state- and the density-dependent correlation functions in the framework of the lowest-order constrained variational (LOCV) method to calculate the TNSF of the 16O nucleus in the 16O(e,e'NN)14C reaction. The Reid soft-core (Reid68) and the Av18 potentials are used as the internucleon interactions. Since, the short-range correlation effects are imposed on the wave functions for the individual channels (e.g., the 1S0 and 3PJ channels); therefore, the defect wave functions are obtained for various channels such that the high relative momenta (p>4fm-1) are ignored. The resulting TNSFs for the 16O nucleus are compared with those of the dressed random phase approximation (DRPA) calculations of Geurts and the experimental predictions, especially those of Onderwater , (NIKHEF group), where reasonable agreement is found. It is shown that the optimized state-dependent defect wave functions have substantial effects on the TNSF and it is not justified to use the simplified parametrized two-body correlation functions in all of the channels. In agreement with the experimental data of Onderwater , the knockout of a 1S0 pair proton dominates the above reaction cross section. Finally, it is demonstrated that the 0+ and 2+ peaks, which are expected to be observed in the above reaction cross section, are moved to the lower momenta of out-going protons when the state-dependent correlation functions are imposed.
Deep Inelastic Scattering from A=3 Nuclei and the Neutron Structure Function
Energy Technology Data Exchange (ETDEWEB)
I. Afnan; F. Bissey; J. Gomez; A. Katramatou; S. Liuti; W. Melnitchouk; G. Petratos; A.W. Thomas
2003-03-01
We present a comprehensive analysis of deep inelastic scattering from {sup 3}He and {sup 3}H, focusing in particular on the extraction of the free neutron structure function, F{sup n}{sub 2}. Nuclear corrections are shown to cancel to within 1-2% for the isospin-weighted ratio of {sup 3}He to {sup 3}H structure functions, which leads to more than an order of magnitude improvement in the current uncertainty on the neutron to proton ratio F{sup 2n}{sub 2}/F{sup p}{sub 2} at large x. Theoretical uncertainties originating tom the nuclear wave function, including possible non-nucleonic components, are evaluated. Measurement of the {sup 3}He and {sup 3}H structure functions will, in addition, determine the magnitude of the EMC effect in all A [lte] 3 nuclei.
Mitochondria: isolation, structure and function.
Picard, Martin; Taivassalo, Tanja; Gouspillou, Gilles; Hepple, Russell T
2011-09-15
Mitochondria are complex organelles constantly undergoing processes of fusion and fission, processes that not only modulate their morphology, but also their function. Yet the assessment of mitochondrial function in skeletal muscle often involves mechanical isolation of the mitochondria, a process which disrupts their normally heterogeneous branching structure and yields relatively homogeneous spherical organelles. Alternatively, methods have been used where the sarcolemma is permeabilized and mitochondrial morphology is preserved, but both methods face the downside that they remove potential influences of the intracellular milieu on mitochondrial function. Importantly, recent evidence shows that the fragmented mitochondrial morphology resulting from routine mitochondrial isolation procedures used with skeletal muscle alters key indices of function in a manner qualitatively similar to mitochondria undergoing fission in vivo. Although these results warrant caution when interpreting data obtained with mitochondria isolated from skeletal muscle, they also suggest that isolated mitochondrial preparations might present a useful way of interrogating the stress resistance of mitochondria. More importantly, these new findings underscore the empirical value of studying mitochondrial function in minimally disruptive experimental preparations. In this review, we briefly discuss several considerations and hypotheses emerging from this work.
Nucleon sea parton densities. Differences for neutrinos and muons
Energy Technology Data Exchange (ETDEWEB)
Barone, V. (Dipt. di Fisica, Univ. di Perugia (Italy) Ist. Nazionale di Fisica Nucleare, Perugia (Italy)); Genovese, M.; Predazzi, E. (Dipt. di Fisica Teorica, Univ. Turin (Italy) Ist. Nazionale di Fisica Nucleare, Turin (Italy)); Nikolaev, N.N. (Dipt. di Fisica Teorica, Univ. Turin (Italy) Ist. Nazionale di Fisica Nucleare, Turin (Italy) European Branch of L.D. Landau Inst., ISI Foundation, Turin (Italy)); Zakharov, B.G. (Inst. of Nuclear Research, Moscow State Univ. (Russia))
1991-10-10
The nucleon sea parton distributions probed by muons and neutrinos are different since excitation of santi s, canti c pairs by muons and canti s, santi c pairs by neutrinos have different mass thresholds. Natural starting points for the structure functions are c{sub {nu}}(x, Q{sup 2}) {approx equal} s{sub {nu}}(x, Q{sup 2}), in {nu} (anti {nu}) interactions and c{sub {mu}}(x, Q{sup 2})<structure functions at small x are predicted. The effects we discuss are in leading twist and persist numerically up to large values of Q{sup 2}. (orig.).
Precision measurement of the neutron spin dependent structure functions
Energy Technology Data Exchange (ETDEWEB)
Kolomensky, Y.G.
1997-02-01
In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g{sub 1}{sup n} (x, Q{sup 2}) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized {sup 3}He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 {le} x {le} 0.7 with an average Q{sup 2} of 5 GeV{sup 2}. The author reports the integral of the spin dependent structure function in the measured range to be {integral}{sub 0.014}{sup 0.7} dx g{sub 1}{sup n}(x, 5 GeV{sup 2}) = {minus}0.036 {+-} 0.004(stat.) {+-} 0.005(syst.). The author observes relatively large values of g{sub 1}{sup n} at low x that call into question the reliability of data extrapolation to x {r_arrow} 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 g{sub 1}{sup p} and g{sub 1}{sup n} 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 Q{sup 2} = 5 GeV{sup 2}, determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule.
Nucleon Form Factors - A Jefferson Lab Perspective
Energy Technology Data Exchange (ETDEWEB)
John Arrington, Kees de Jager, Charles F. Perdrisat
2011-06-01
The charge and magnetization distributions of the proton and neutron are encoded in their elastic electromagnetic form factors, which can be measured in elastic electron--nucleon scattering. By measuring the form factors, we probe the spatial distribution of the proton charge and magnetization, providing the most direct connection to the spatial distribution of quarks inside the proton. For decades, the form factors were probed through measurements of unpolarized elastic electron scattering, but by the 1980s, progress slowed dramatically due to the intrinsic limitations of the unpolarized measurements. Early measurements at several laboratories demonstrated the feasibility and power of measurements using polarization degrees of freedom to probe the spatial structure of the nucleon. A program of polarization measurements at Jefferson Lab led to a renaissance in the field of study, and significant new insight into the structure of matter.
The structure and function of fungal cells
Nozawa, Y.
1984-01-01
The structure and function of fungal cell walls were studied with particular emphasis on dermatophytes. Extraction, isolation, analysis, and observation of the cell wall structure and function were performed. The structure is described microscopically and chemically.
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.
Tissue Factor Structure and Function
Directory of Open Access Journals (Sweden)
Saulius Butenas
2012-01-01
Full Text Available Tissue factor (TF is an integral membrane protein that is essential to life. It is a component of the factor VIIa-TF complex enzyme and plays a primary role in both normal hemostasis and thrombosis. With a vascular injury, TF becomes exposed to blood and binds plasma factor VIIa, and the resulting complex initiates a series of enzymatic reactions leading to clot formation and vascular sealing. Many cells, both healthy, and tumor cells, produce detectable amounts of TF, especially when they are stimulated by various agents. Despite the relative simplicity and small size of TF, there are numerous contradictory reports about the synthesis and presentation of TF on blood cells and circulation in normal blood either on microparticles or as a soluble protein. Another subject of controversy is related to the structure/function of TF. It has been almost commonly accepted that cell-surface-associated TF has low (if any activity, that is, is “encrypted” and requires specific conditions/reagents to become active, that is, “decrypted.” However there is a lack of agreement related to the mechanism and processes leading to alterations in TF function. In this paper TF structure, presentation, and function, and controversies concerning these features are discussed.
Nucleon Electromagnetic Form Factors
Energy Technology Data Exchange (ETDEWEB)
Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi
2007-10-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.
A Quark Transport Theory to describe Nucleon--Nucleon Collisions
Kalmbach, U; Biro, T S; Mosel, U
1993-01-01
On the basis of the Friedberg-Lee model we formulate a semiclassical transport theory to describe the phase-space evolution of nucleon-nucleon collisions on the quark level. The time evolution is given by a Vlasov-equation for the quark phase-space distribution and a Klein-Gordon equation for the mean-field describing the nucleon as a soliton bag. The Vlasov equation is solved numerically using an extended testparticle method. We test the confinement mechanism and mean-field effects in 1+1 dimensional simulations.
Nucleon electromagnetic form factors with Wilson fermions
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Haegler, P. [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (GB). School of Physics] (and others)
2007-10-15
The nucleon electromagnetic form factors continue to be of major interest for experimentalists and phenomenologists alike. They provide important insights into the structure of nuclear matter. For a range of interesting momenta they can be calculated on the lattice. The limiting factor continues to be the value of the pion mass. We present the latest results of the QCDSF collaboration using gauge configurations with two dynamical, non-perturbatively improved Wilson fermions at pion masses as low as 350 MeV. (orig.)
Progress in the Calculation of Nucleon Transition form Factors
Eichmann, Gernot
2016-10-01
We give a brief account of the Dyson-Schwinger and Faddeev-equation approach and its application to nucleon resonances and their transition form factors. We compare the three-body with the quark-diquark approach and present a quark-diquark calculation for the low-lying nucleon resonances including scalar, axialvector, pseudoscalar and vector diquarks. We also discuss the timelike structure of transition form factors and highlight the advantages of form factors over helicity amplitudes.
Progress in the calculation of nucleon transition form factors
Eichmann, Gernot
2016-01-01
We give a brief account of the Dyson-Schwinger and Faddeev-equation approach and its application to nucleon resonances and their transition form factors. We compare the three-body with the quark-diquark approach and present a quark-diquark calculation for the low-lying nucleon resonances including scalar, axialvector, pseudoscalar and vector diquarks. We also discuss the timelike structure of transition form factors and highlight the advantages of form factors over helicity amplitudes.
The nucleon in a periodic magnetic field
Agadjanov, Andria; Rusetsky, Akaki
2016-01-01
The energy shift of a nucleon in a static periodic magnetic field is evaluated at second order in the external field strength in perturbation theory. It is shown that the measurement of this energy shift on the lattice allows one to determine the unknown subtraction function in the forward doubly-virtual Compton scattering amplitude. The limits of applicability of the obtained formula for the energy shift are discussed.
Dense nucleonic matter and the renormalization group
Drews, Matthias; Klein, Bertram; Weise, Wolfram
2013-01-01
Fluctuations are included in a chiral nucleon-meson model within the framework of the functional renormalization group. The model, with parameters fitted to reproduce the nuclear liquid-gas phase transition, is used to study the phase diagram of QCD. We find good agreement with results from chiral effective field theory. Moreover, the results show a separation of the chemical freeze-out line and chiral symmetry restoration at large baryon chemical potentials.
Dense nucleonic matter and the renormalization group
Directory of Open Access Journals (Sweden)
Drews Matthias
2014-03-01
Full Text Available Fluctuations are included in a chiral nucleon-meson model within the framework of the functional renormalization group. The model, with parameters fitted to reproduce the nuclear liquid-gas phase transition, is used to study the phase diagram of QCD. We find good agreement with results from chiral effective field theory. Moreover, the results show a separation of the chemical freeze-out line and chiral symmetry restoration at large baryon chemical potentials.
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.
Target mass corrections for spin-dependent structure functions in collinear factorization
Accardi, A
2008-01-01
We derive target mass corrections (TMC) for the spin-dependent nucleon structure function g1 and polarization asymmetry A1 in collinear factorization at leading twist. The TMCs are found to be significant for g1 at large xB, even at relatively high Q^2 values, but largely cancel in A1. A comparison of TMCs obtained from collinear factorization and from the operator product expansion shows that at low Q^2 the corrections drive the proton A1 in opposite directions.
Microscopic Calculation of the Inclusive Electron Scattering Structure Function in 16O
Mihaila, Bogdan; Heisenberg, Jochen H.
2000-02-01
We calculate the charge form factor and the longitudinal structure function for 16O and compare with the available experimental data, up to a momentum transfer of 4 fm-1. The ground-state correlations are generated using the coupled-cluster [ exp\\(S\\)] method, together with the realistic v18 NN interaction and the Urbana IX three-nucleon interaction. Center-of-mass corrections are dealt with by adding a center-of-mass Hamiltonian to the usual internal Hamiltonian, and by means of a many-body expansion for the computation of the observables measured in the center-of-mass system.
Microscopic calculation of the inclusive electron scattering structure function in O-16
Mihaila, B; Mihaila, Bogdan; Heisenberg, Jochen
2000-01-01
We calculate the charge form factor and the longitudinal structure function for $^{16}$O and compare with the available experimental data, up to a momentum transfer of 4 fm$^{-1}$. The ground state correlations are generated using the coupled cluster [exp(S}] method, together with the realistic v-18 NN interaction and the Urbana IX three-nucleon interaction. Center-of-mass corrections are dealt with by adding a center-of-mass Hamiltonian to the usual internal Hamiltonian, and by means of a many-body expansion for the computation of the observables measured in the center-of-mass system.
Probing short-range nucleon-nucleon interactions with an electron-ion collider
Miller, Gerald A.; Sievert, Matthew D.; Venugopalan, Raju
2016-04-01
We derive the cross section for exclusive vector meson production in high-energy deeply inelastic scattering off a deuteron target that disintegrates into a proton and a neutron carrying large relative momentum in the final state. This cross section can be expressed in terms of a novel gluon transition generalized parton distribution (T-GPD); the hard scale in the final state makes the T-GPD sensitive to the short-distance nucleon-nucleon interaction. We perform a toy model computation of this process in a perturbative framework and discuss the time scales that allow the separation of initial- and final-state dynamics in the T-GPD. We outline the more general computation based on the factorization suggested by the toy computation: In particular, we discuss the relative role of "pointlike" and "geometric" Fock configurations that control the parton dynamics of short-range nucleon-nucleon scattering. With the aid of exclusive J /ψ production data at the Hadron-Electron Ring Accelerator at DESY, as well as elastic nucleon-nucleon cross sections, we estimate rates for exclusive deuteron photodisintegration at a future Electron-Ion Collider (EIC). Our results, obtained using conservative estimates of EIC integrated luminosities, suggest that center-of-mass energies sNN˜12 GeV2 of the neutron-proton subsystem can be accessed. We argue that the high energies of the EIC can address outstanding dynamical questions regarding the short-range quark-gluon structure of nuclear forces by providing clean gluon probes of such "knockout" exclusive reactions in light and heavy nuclei.
Pion and kaon structure functions at 12 GeV JLab and EIC
Horn, Tanja
2017-01-01
Pions and kaons are, along with protons and neutrons, the main building blocks of nuclear matter. They are connected to the Goldstone modes of dynamical chiral symmetry breaking, the mechanism thought to generate all hadron mass in the visible universe. The distribution of the fundamental constituents, the quarks and gluons, is expected to be different in pions, kaons, and nucleons. However, experimental data are sparse. As a result, there has been persistent doubt about the behavior of the pion's valence quark structure function at large Bjorken-x and virtually nothing is known about the contribution of gluons. A 12 GeV JLab experiment using tagged DIS may contribute to the resolution of the former. The Electron-Ion Collider with an acceptance optimized for forward physics could provide access to structure functions over a larger kinematic region. This would allow for measurements testing if the origin of mass is encoded in the differences of gluons in pions, kaons, and nucleons, and measurements testing assumptions used in the extraction of structure functions and the pion and kaon form factors. Electroweak measurements at an EIC would also potentially allow to disentangle the role of quark flavors at high x. In this talk we will discuss the prospects of such measurements. Supported in part by NSF grants PHY-1306227 and PHY-1306418.
Adler, S S; Ajitanand, N N; Akiba, Y; Al-Jamel, A; Alexander, J; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Averbeck, R; Awes, T C; Babintsev, V; Baldisseri, Alberto; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bjorndal, M T; Boissevain, J G; Borel, H; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Büsching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Comets, M P; Constantin, P; Csanad, M; Csorg}o, T; Cussonneau, J P; D'Enterria, D; Das, K; Dávid, G; Deák, F; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Drachenberg, J L; Drapier, O; Drees, A; Durum, A; Dutta, D; Dzhordzhadze, V; Efremenko, Yu V; Enyo, H; Espagnon, B; Esumi, S; Fields, D E; Finck, C; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Zeev; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fung, S Y; Gadrat, S; Germain, M; Glenn, A; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse-Perdekamp, M; Gustafsson, Hans Åke; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hasuko, K; Hayano, R; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hidas, P; Hiejima, H; Hill, J C; Hobbs, R; Holzmann, W; Homma, K; Hong, B; Hoover, A; Horaguchi, T; Ichihara, T; Ikonnikov, V V; Imai, K; Inaba, M; Inuzuka, M; Isenhower, D; Isenhower, L; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kaneta, M; Kang, J H; Katou, K; Kawabata, T; Kazantsev, A V; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, E; Kim, G B; Kim, H J; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klein-Bösing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Kohara, R; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kunde, G J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Le Bornec, Y; Lebedev, A; Leckey, S; Lee, D M; Leitch, M J; Leite, M A L; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Maguire, C F; Makdisi, Y I; Malakhov, A; Man'ko, V I; Mao, Y; Martínez, G; Masui, H; Matathias, F; Matsumoto, T; McCain, M C; McGaughey, P L; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mukhopadhyay, D; Muniruzzaman, M; Nagamiya, S; Nagle, J L; Nakamura, T; Newby, J; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, H; Okada, K; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Penev, V; Peng, J C; Pereira, H; Peresedov, V; Pierson, A; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qualls, J M; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rykov, V L; Ryu, S S; Saitô, N; Sakaguchi, T; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T A; Shigaki, K; Shimomura, M; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Soldatov, A; Soltz, R A; Sondheim, W E; Sørensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarjan, P; Thomas, T L; Togawa, M; Tojo, J; Torii, H; Towell, R S; Tram, V N; Tserruya, Itzhak; Tsuchimoto, Y; Tydesjo, H; Tyurin, N; Uam, T J; Velkovska, J; Velkovsky, M; Veszpremi, V; Vinogradov, A A; Volkov, M A; Vznuzdaev, E; Wang, X R; Watanabe, Y; White, S N; Willis, N; Wohn, F K; Woody, C L; Xie, W; Yanovich, A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zimányi, J; Zolin, L; Zong, X; van Hecke, H W
2007-01-01
We present transverse momentum (p_T) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at \\sqrts = 200 GeV for four centrality classes. Nucleon-gold collisions were selected by tagging events in which a spectator nucleon was observed in one of two forward rapidity detectors. The spectra and yields were investigated as a function of the number of binary nucleon-nucleon collisions, \
Induced Hyperon-Nucleon-Nucleon Interactions and the Hyperon Puzzle
Wirth, Roland
2016-01-01
We present the first ab initio calculations for $p$-shell hypernuclei including hyperon-nucleon-nucleon (YNN) contributions induced by a Similarity Renormalization Group transformation of the initial hyperon-nucleon interaction. The transformation including the YNN terms conserves the spectrum of the Hamiltonian while drastically improving model-space convergence of the Importance-Truncated No-Core Shell Model, allowing a precise extraction of binding and excitation energies. Results using a hyperon-nucleon interaction at leading order in chiral effective field theory for lower- to mid-$p$-shell hypernuclei show a good reproduction of experimental excitation energies while hyperon binding energies are typically overestimated. The induced YNN contributions are strongly repulsive and we show that they are related to a decoupling of the $\\Sigma$ hyperons from the hypernuclear system, i.e., a suppression of the $\\Lambda$-$\\Sigma$ conversion terms in the Hamiltonian. This is linked to the so-called hyperon puzzle ...
Structure and function of aggrecan
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Aggrecan is the major proteoglycan in the articular cartilage. This molecule is important in the proper functioning of articular cartilage because it provides a hydrated gel structure (via its interaction with hyaluronan and link protein) that endows the cartilage with load-bearing properties. It is also crucial in chondroskeletal morphogenesis during development. Aggrecan is a multimodular molecule expressed by chondrocytes. Its core protein is composed of three globular domains (Gl, G2, and G3) and a large extended region (CS) between G2 and G3 for glycosaminoglycan chain attachment. G1 comprises the amino terminus of the core protein. This domain has the same structural motif as link protein. Functionally, the G1 domain interacts with hyaluronan acid and link protein, forming stable ternary complexes in the extracellular matrix.G2 is homologous to the tandem repeats of G1 and of link protein and is involved in product processing. G3makes up the carboxyl terminus of the core protein. It enhances glycosaminoglycan modification and product secretion. Aggrecan plays an important role in mediating chondrocyte-chondrocyte and chondrocyte-matrix interactions through its ability to bind hyaluronan.
Electromagnetic Excitation of Nucleon Resonances
Tiator, L; Kamalov, S S; Vanderhaeghen, M
2011-01-01
Recent progress on the extraction of electromagnetic properties of nucleon resonance excitation through pion photo- and electroproduction is reviewed. Cross section data measured at MAMI, ELSA, and CEBAF are analyzed and compared to the analysis of other groups. On this basis, we derive longitudinal and transverse transition form factors for most of the four-star nucleon resonances. Furthermore, we discuss how the transition form factors can be used to obtain empirical transverse charge densities. Contour plots of the thus derived densities are shown for the Delta, Roper, S11, and D13 nucleon resonances.
Nucleon-Nucleon Scattering From Fully-Dynamical Lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Konstantinos Orginos; Martin Savage; Paulo Bedaque; Silas Beane
2006-07-01
We present results of the first fully-dynamical lattice QCD determination of nucleon-nucleon scattering lengths in the 1 S0 channel and 3 S1 - 3 D1 coupled channels. The calculations are performed with domain-wall valence quarks on the MILC staggered configurations with lattice spacing of b = 0.125 fm in the isospin-symmetric limit, and in the absence of electromagnetic interactions
Neutrino-nucleon cross sections at energies of Megaton-scale detectors
Directory of Open Access Journals (Sweden)
Gazizov A.
2016-01-01
Full Text Available An updated set of (antineutrino-nucleon charged and neutral current cross sections at 3 GeV ≲ Eν ≲100 GeV is presented. These cross sections are of particular interest for the detector optimization and data processing and interpretation in the future Megaton-scale experiments like PINGU, ORCA, and Hyper-Kamiokande. Finite masses of charged leptons and target mass corrections in exclusive and deep inelastic (ν̅νN interactions are taken into account. A new set of QCD NNLO parton density functions, ABMP15, is used for calculation of the DIS cross sections. The sensitivity of the cross sections to phenomenological parameters and to extrapolations of the nucleon structure functions to small x and Q2 is studied. An agreement within the uncertainties of our calculations with experimental data is demonstrated.
Energy Technology Data Exchange (ETDEWEB)
Rebreyend, D
2006-10-15
The photoproduction of mesons on the nucleon gives a direct access to its spectroscopy and is a promising way for the study of the structure of the nucleon. The GRAAL experiment uses a tagged and polarized photon beam produced through the Compton diffusion of laser photons on the electrons circulating in the ESRF storage ring. The combination of this photon beam and an efficient detection system has allowed a series of measurements concerning the photoproduction of light mesons on the proton and on the neutron. The first 4 chapters are dedicated to the nucleon spectroscopy: the nucleon models and their consequences on the excited levels are recalled, the experimental technique used is described and the difficulties due to the extraction of relevant data are presented. Highly accurate measurements of cross-sections, {sigma} asymmetry beams and resonance parameters have been performed. The last part is dedicated to the principle of the measurement of the electric dipole momentum of the neutron. (A.C.)
Nucleon Polarizabilities: from Compton Scattering to Hydrogen Atom
Hagelstein, Franziska; Pascalutsa, Vladimir
2015-01-01
We review the current state of knowledge of the nucleon polarizabilities and of their role in nucleon Compton scattering and in hydrogen spectrum. We discuss the basic concepts, the recent lattice QCD calculations and advances in chiral effective-field theory. On the experimental side, we review the ongoing programs aimed to measure the nucleon (scalar and spin) polarizabilities via the Compton scattering processes, with real and virtual photons. A great part of the review is devoted to the general constraints based on unitarity, causality, discrete and continuous symmetries, which result in model-independent relations involving nucleon polarizabilities. We (re-)derive a variety of such relations and discuss their empirical value. The proton polarizability effects are presently the major sources of uncertainty in the assessment of the muonic hydrogen Lamb shift and hyperfine structure. Recent calculations of these effects are reviewed here in the context of the "proton-radius puzzle". We conclude with summary...
Transverse momentum distributions inside the nucleon from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Musch, Bernhard Ulrich
2009-05-29
Nucleons, i.e., protons and neutrons, are composed of quarks and gluons, whose interactions are described by the theory of quantum chromodynamics (QCD), part of the standard model of particle physics. This work applies lattice QCD to compute quark momentum distributions in the nucleon. The calculations make use of lattice data generated on supercomputers that has already been successfully employed in lattice studies of spatial quark distributions (''nucleon tomography''). In order to be able to analyze transverse momentum dependent parton distribution functions, this thesis explores a novel approach based on non-local operators. One interesting observation is that the transverse momentum dependent density of polarized quarks in a polarized nucleon is visibly deformed. A more elaborate operator geometry is required to enable a quantitative comparison to high energy scattering experiments. First steps in this direction are encouraging. (orig.)
Dispersive analysis of the scalar form factor of the nucleon
Hoferichter, M; Kubis, B; Meißner, U -G
2012-01-01
Based on the recently proposed Roy-Steiner equations for pion-nucleon scattering, we derive a system of coupled integral equations for the pi pi --> N-bar N and K-bar K --> N-bar N S-waves. These equations take the form of a two-channel Muskhelishvili-Omnes problem, whose solution in the presence of a finite matching point is discussed. We use these results to update the dispersive analysis of the scalar form factor of the nucleon fully including K-bar K intermediate states. In particular, we determine the correction Delta_sigma=sigma(2M_pi^2)-sigma_{pi N}, which is needed for the extraction of the pion-nucleon sigma term from pi N scattering, as a function of pion-nucleon subthreshold parameters and the pi N coupling constant.
The form factors of the nucleons
Perdrisat, C. F.
2013-11-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double-polarization experiments, in comparison with with previous unpolarized cross section data. Here we will review the experimental data base in view of the new results for the proton and the neutron, obtained at MIT-Bates, JLab and MAMI. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed. In particular, the possibility that the proton is non-spherical in its ground state, and that the transverse charge density are model independently defined in the infinite momentum frame. Likewise, flavor decomposition of the nucleon form factors into dressed u and d quark form factors, may give information about the quark-diquark structure of the nucleon. The current proton radius "crisis" will also be discussed.
The Form Factors of the Nucleons
Energy Technology Data Exchange (ETDEWEB)
Perdrisat, Charles F. [William and Mary College, JLAB
2013-11-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double-polarization experiments, in comparison with with pre-vious unpolarized cross section data. Here we will review the experimental data base in view of the new results for the proton and the neutron, obtained at MIT-Bates, JLab and MAMI. The rapid evolution of phenomenological models triggered by these high- precision experiments will be discussed. In particular, the possibility that the proton is non-spherical in its ground state, and that the transverse charge density are model in- dependently defined in the infinite momentum frame. Likewise, flavor decomposition of the nucleon form factors into dressed u and d quark form factors, may give information about the quark-diquark structure of the nucleon. The current proton radius "crisis" will also be discussed.
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.
Hen, O; Piasetzky, E; Weinstein, L B
2016-01-01
This article reviews our current understanding of how the internal quark structure of a nucleon bound in nuclei differs from that of a free nucleon. We focus on the interpre- tation of measurements of the EMC effect for valence quarks, a reduction in the Deep Inelastic Scattering (DIS) cross-section ratios for nuclei relative to deuterium, and its possible connection to nucleon-nucleon Short-Range Correlations (SRC) in nuclei. Our review of the available experimental and theoretical evidence shows that there is a phe- nomenological relation between between the EMC effect and the effects of SRC that is not an accident. There is an underlying cause of both effects: the influence of strongly correlated neutron-proton pairs is largely responsible. This conclusion needs to be so- lidified by the future experiments and improved theoretical analyses that are discussed herein.
Electroexcitation of nucleon resonances
Aznauryan, I G
2011-01-01
We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited states, which have been measured in a range of Q2 up to 8 and 4.5 GeV2 for the Delta(1232)P33, N(1535)S11 and N(1440)P11, N(1520)D13}, respectively. These results have been confronted with calculations based on lattice QCD, large-Nc relations, perturbative QCD (pQCD), and QCD-inspired models. The amplitudes for the Delta(1232) indicate large pion-cloud contributions at low Q2 and don't show any sign of approaching the pQCD regime for Q2 0.5 GeV2, confirming a long-standing prediction of the constituent quark model. The interpretation of the moments of resonance transition form factors in terms of transition transverse charge distributions in infinite momentum frame is presented.
Tkachenko, S; Kuhn, S E; Zhang, J; Arrington, J; Bosted, P; Bültmann, S; Christy, M E; Fenker, H; Griffioen, K A; Kalantarians, N; Keppel, C E; Melnitchouk, W; Tvaskis, V; Adhikari, K P; Aghasyan, M; Amaryan, M J; Pereira, S Anefalos; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Cole, P L; Contalbrigo, M; Cortes, O; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fleming, J A; Garillon, B; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gothe, R W; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Hicks, K; Ho, D; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jo, H S; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Koirala, S; Kubarovsky, V; Kuleshov, S V; Lenisa, P; Lewis, S; Livingston, K; Lu, H; MacCormick, M; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Mineeva, T; Mirazita, M; Mokeev, V; Montgomery, R A; Moutarde, H; Camacho, C Munoz; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Park, K; Pasyuk, E; Phillips, J J; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Puckett, A J R; Rimal, D; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Schott, D; Schumacher, R A; Seder, E; Senderovich, I; Sharabian, Y G; Simonyan, A; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S; Stepanyan, S S; Strauch, S; Tang, W; Ungaro, M; Vlassov, A V; Voskanyan, H; Voutier, E; Walford, N K; Watts, D; Wei, X; Weinstein, L B; Wood, M H; Zana, L; Zonta, I
2014-01-01
Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. The Barely Off-shell Nucleon Structure (BONuS) experiment at Jefferson Lab measured the inelastic electron deuteron scattering cross section, tagging spectator protons in coincidence with the scattered electrons. This method reduces nuclear binding uncertainties significantly and has allowed for the first time a (nearly) model independent extraction of the neutron structure function. A novel compact radial time projection chamber was built to detect protons with momentum between 70 and 150 MeV/c. For the extraction of the free neutron structure function $F_{2n}$, spectator protons at backward angle and with...
Energy Technology Data Exchange (ETDEWEB)
Guillon, B
2005-10-15
In the framework of the Quantum Chromodynamics (QCD), the nucleon is described as being composed of three valence quarks surrounded by a sea of virtual quark-antiquark pairs and gluons. If the role of this virtual sea in the nucleon properties is inferred to be important, this contribution is still poorly understood. In this context, we study the role of the strange quarks in the nucleon since this is the lightest quark flavor of the sea with no valence contribution. We are determining its contribution to the charge and magnetization distributions in the nucleon via parity violation experiments. The measurement is performed by elastically scattering polarized electrons from nucleon target. A world wide program in which the G0 experiment takes place has been performing for a decade. The G0 experiment and the analysis of the results from its forward angles phase are the topics of this thesis. This document presents the physics case of the strangeness content of the nucleon (mass, spin, impulsion). It describes also the formalism related to the electroweak probe and the form factors, and then the principle of parity violating asymmetry measurement. The G0 experimental setup, which was built and installed in the Hall C of the Jefferson Laboratory (Usa), is detailed. This set-up was designed for the measurement of asymmetries of the order of 10{sup -6} with an overall relative uncertainty better than 10 %, over a momentum transfer range 0.1-1 (GeV/c){sup 2}. The various steps of the data analysis are exposed. They have allowed us to start from measured counting rates to reach parity violating physics asymmetries. This required a careful treatment of the various sources of systematical errors which is discussed extensively. Finally the results from the G0 forward angle measurement, its comparison with others experiments and with theoretical models, are presented. They support a non null strange quark contribution. (author)
Nucleonic helicity distributions revisited with an emphasis on their evolutions and twists
Indian Academy of Sciences (India)
Rajen Kundu
2014-12-01
In this work, we uphold and extend the formalism advocated by us more than a decade ago in order to extract information on various distribution functions describing nucleonic helicity structure and calculate a complete set of splitting functions relevant for their quantum chromodynamics (QCD) evolutions using light-front Hamiltonian perturbation theory in light front gauge + = 0. Twist-two structures of the helicity distributions are self-evident in our calculation. Sum rules associated with these helicity distributions are also verified in a frame-independent way.
Spin-dependent structure functions in nuclear matter and the polarized EMC effect.
Cloët, I C; Bentz, W; Thomas, A W
2005-07-29
An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu--Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions and find that we are readily able to reproduce both nuclear matter saturation and the experimental F2N(A)/F2N ratio, that is, the European Muon Collaboration (EMC) effect. Applying this framework to determine g1p(A), we find that the ratio g1p(A)/g1p differs significantly from unity, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which, if confirmed experimentally, will reveal much about the quark structure of nuclear matter.
Structure and functions of fungal cell surfaces
Nozawa, Y.
1984-01-01
A review with 24 references on the biochemistry, molecular structure, and function of cell surfaces of fungi, especially dermatophytes: the chemistry and structure of the cell wall, the effect of polyene antibiotics on the morphology and function of cytoplasmic membranes, and the chemical structure and function of pigments produced by various fungi are discussed.
Structure Function Estimated From Histological Tissue Sections.
Han, Aiguo; O'Brien, William D
2016-09-01
Ultrasonic scattering is determined by not only the properties of individual scatterers but also the correlation among scatterer positions. The role of scatterer spatial correlation is significant for dense medium, but has not been fully understood. The effect of scatterer spatial correlation may be modeled by the structure function as a frequency-dependent factor in the backscatter coefficient (BSC) expression. The structure function has been previously estimated from the BSC data. The aim of this study is to estimate the structure function from histology to test if the acoustically estimated structure function is indeed caused by the scatterer spatial distribution. Hematoxylin and eosin stained histological sections from dense cell pellet biophantoms were digitized. The scatterer positions were determined manually from the histological images. The structure function was calculated from the extracted scatterer positions. The structure function obtained from histology showed reasonable agreement in the shape but not in the amplitude, compared with the structure function previously estimated from the backscattered data. Fitting a polydisperse structure function model to the histologically estimated structure function yielded relatively accurate cell radius estimates ([Formula: see text]). Furthermore, two types of mouse tumors that have similar cell size and shape but distinct cell spatial distributions were studied, where the backscattered data were shown to be related to the cell spatial distribution through the structure function estimated from histology. In conclusion, the agreement between acoustically estimated and histologically estimated structure functions suggests that the acoustically estimated structure function is related to the scatterer spatial distribution.
Novel Structure and Function of Typhoid Toxin
... Matters NIH Research Matters July 29, 2013 Novel Structure and Function of Typhoid Toxin Structure of typhoid toxin, showing the 2 A subunits ( ... to cultured cells. The scientists next determined the structure of the typhoid toxin. The toxin was already ...
Electroexcitation of nucleon resonances
Energy Technology Data Exchange (ETDEWEB)
Inna Aznauryan, Volker D. Burkert
2012-01-01
We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited states, which have been measured in a range of Q2 up to 8 and 4.5 GeV2 for the Delta(1232)P33, N(1535)S11 and N(1440)P11, N(1520)D13, respectively. These results have been confronted with calculations based on lattice QCD, large-Nc relations, perturbative QCD (pQCD), and QCD-inspired models. The amplitudes for the Delta(1232) indicate large pion-cloud contributions at low Q2 and don't show any sign of approaching the pQCD regime for Q2<7 GeV2. Measured for the first time, the electroexcitation amplitudes of the Roper resonance, N(1440)P11, provide strong evidence for this state as a predominantly radial excitation of a three-quark (3q) ground state, with additional non-3-quark contributions needed to describe the low Q2 behavior of the amplitudes. The longitudinal transition amplitude for the N(1535)S11 was determined and has become a challenge for quark models. Explanations may require large meson-cloud contributions or alternative representations of this state. The N(1520)D13 clearly shows the rapid changeover from helicity-3/2 dominance at the real photon point to helicity-1/2 dominance at Q2 > 0.5 GeV2, confirming a long-standing prediction of the constituent quark model. The interpretation of the moments of resonance transition form factors in terms of transition transverse charge distributions in infinite momentum frame is presented.
Soft nanotechnology: "structure" vs. "function".
Whitesides, George M; Lipomi, Darren J
2009-01-01
This paper offers a perspective on "soft nanotechnology"; that is, the branch of nanotechnology concerned with the synthesis and properties of organic and organometallic nanostructures, and with nanofabrication using techniques in which soft components play key roles. It begins with a brief history of soft nanotechnology. This history has followed a path involving a gradual shift from the promise of revolutionary electronics, nanorobotics, and other futuristic concepts, to the realization of evolutionary improvements in the technology for current challenges in information technology, medicine, and sustainability. Soft nanoscience is an area that is occupied principally by chemists, and is in many ways indistinguishable from "nanochemistry". The paper identifies the natural tendency of its practitioners--exemplified by the speakers at this Faraday Discussion--to focus on synthesis and structure, rather than on function and application, of nanostructures. Soft nanotechnology has the potential to apply to a wide variety of large-scale applied (information technology, healthcare cost reduction, sustainability, energy) and fundamental (molecular biochemistry, cell biology, charge transport in organic matter) problems.
Structure and Function of Lipase
DEFF Research Database (Denmark)
Skjold-Jørgensen, Jakob
Lipases are triacylglycerol hydrolases (EC 3.1.1.3) which are able to act on water-insoluble esters, butdisplay very low activity towards water-soluble, monomeric substrates. This is ascribed to theircharacteristic activation mechanism occurring at the boundary between water and lipid, i.e. the w......Lipases are triacylglycerol hydrolases (EC 3.1.1.3) which are able to act on water-insoluble esters, butdisplay very low activity towards water-soluble, monomeric substrates. This is ascribed to theircharacteristic activation mechanism occurring at the boundary between water and lipid, i.......e. the waterlipidinterface. For Thermomyces lanuginosus lipase (TlL) and related lipases, activation of the enzymeinvolves a rearrangement of a structural domain, called the “lid”, which covers the active site inhomogenous aqueous solution. At the water-lipid interface, the lid is displaced from the active site andmoves...... towards an open conformation enabling the substrate to gain access, thus initiating catalysis.Lipases have been studied for decades and their functional features have drawn much attention withinindustrial applications since their first discovery. However, given that their molecular action takes placeat...
The spin dependent structure function g{sub 1} of the deuteron and the proton
Energy Technology Data Exchange (ETDEWEB)
Klostermann, L.
1995-02-27
This thesis presents a study on the spin structure of the nucleon, via deep inelastic scattering (DIS) of polarised nuons on polarised proton and deuterium targets. The work was done in the Spin Muon Collaboration (SMC) at CERN in Geneva. From the asymmetry in the scattering cross section for nucleon and lepton spins parallel and anti-parallel, one con determine the spin dependent structure function g{sub 1}, which contains information on the quark and gluon spin distribution functions. The interpretation in the frame work of the quark parton model (QPM) of earlier results on g{sub 1}{sup p} by the European Muon Collaboration (EMC), gave an indication that only a small fraction of the proton spin, compatible with zero, is carried by the spins of the constituent quarks. The SMC was set up to check this unexpected result with improved accuracy, and to combine measurements of g{sub 1}{sup p} and g{sub 1}{sup d} to test a fundamental sum rule in quantum chromodynamics (QCD), the Bjorken sum rule. (orig./WL).
Systematics of intermediate-energy single-nucleon removal cross sections
Tostevin, J A
2014-01-01
There is now a large and increasing body of experimental data and theoretical analyses for reactions that remove a single nucleon from an intermediate-energy beam of neutron- or proton-rich nuclei. In each such measurement, one obtains the inclusive cross section for the population of all bound final states of the mass A-1 reaction residue. These data, from different regions of the nuclear chart, and that involve weakly- and strongly-bound nucleons, are compared with theoretical expectations. These calculations include an approximate treatment of the reaction dynamics and shell-model descriptions of the projectile initial state, the bound final states of the residues, and the single-particle strengths computed from their overlap functions. The results are discussed in the light of recent data, more exclusive tests of the eikonal dynamical description, and calculations that take input from more microscopic nuclear structure models.
Superscaling analyses, lepton scattering and nucleon momentum distributions in nuclei
Antonov, A N; Gaidarov, M K; Caballero, J A; Barbaro, M B; Moya de Guerra, E
2010-01-01
It is shown that superscaling is due to the high-momentum tail of the nucleon momentum distribution n(k) which is similar for all nuclei and is caused by the short-range and tensor nucleon-nucleon correlations. It is pointed out also that superscaling gives information about the general power-law asymptotics of n(k) and the nucleon-nucleon forces in the nuclear medium. The Coherent Density Fluctuation Model (CDFM) is used to calculate the total, longitudinal and transverse scaling functions on the basis of the hadronic tensor and the corresponding response functions in the RFG model. The results show a good agreement with the data and superscaling of the scaling function f(ψ′) for negative ψ′ including the region ψ′ < −1, where the RFGmodel fails. The CDFM scaling functions are used to calculate the cross sections of the quasielastic (QE) electron scattering on nuclei in the mass region 12 < A < 208, as well as charge-changing and neutral current neutrino (antineutrino) scattering on 12C i...
A narrow structure in the excitation function of eta-photoproduction off the neutron
Werthmueller, D; Keshelashvili, I; Aguar-Bartolome, P; Ahrens, J; Annand, J R M; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Demissie, B; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Glazier, D I; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Huber, G M; Jaegle, I; Jahn, O; Jude, T C; Kaeser, A; Kashevarov, V L; Kondratiev, R; Korolija, M; Kruglov, S P; Krusche, B; Kulbardis, A; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McNicoll, E F; Metag, V; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S N; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D; Starostin, A; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P
2013-01-01
The photoproduction of $\\eta$-mesons off nucleons bound in $^2$H and $^3$He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the $\\eta\\rightarrow 2\\gamma$ and $\\eta\\rightarrow 3\\pi^0$ decays and the recoil nucleons were detected with an almost $4\\pi$ electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of $\\gamma n\\rightarrow n\\eta$. The results from the two measurements are consistent taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are $W$ = (1670$\\pm$5) MeV and $\\Gamma$ =(30$\\pm$15) MeV. For the first time precise results for the angular dependence of this structure have been ext...
Nucleon-nucleon scattering from effective field theory
Kaplan, D B; Wise, M B; Kaplan, David B; Savage, Martin J; Wise, Mark B
1996-01-01
We perform a nonperturbative calculation of the 1S0 nucleon-nucleon scattering amplitude, using an effective field theory (EFT) expansion. We use dimensional regularization throughout, and the MS-bar renormalization scheme; our final result depends only on physical observables. We show that the EFT expansion of the real part of the inverse of the Feynman amplitude converges at momenta much greater than the scale that characterizes the derivative expansion of the EFT Lagrangian. Our conclusions are optimistic about the applicability of an EFT approach to the quantitative study of nuclear matter.
The Anapole Moment of the Deuteron with the Argonne v18 Nucleon-Nucleon Interaction Model
Hyun, C H; Hyun, Chang Ho; Desplanques, Bertrand
2003-01-01
We calculate the deuteron anapole moment with the wave functions obtained from the Argonne $v18$ nucleon-nucleon interaction model. The anapole moment operators are considered at the leading order. To minimize the uncertainty due to a lack of current conservation, we calculate the matrix element of the anapole moment from the original definition. In virtue of accurate wave functions, we can obtain a more precise value of the deuteron anapole moment which contains less uncertainty than the former works. We obtain a result reduced by more than 25% in the magnitude of the deuteron anapole moment. The reduction of individual nuclear contributions is much more important however, varying from a factor 2 for the spin part to a factor 4 for the convection and associated two-body currents.
Overview of the nucleon spin studies at COMPASS
Directory of Open Access Journals (Sweden)
Franco Celso
2014-04-01
Full Text Available The COMPASS experiment [1] at CERN is one of the leading experiments studying the spin structure of the nucleon. These studies are being carried on since 2002, by measuring hadrons produced in deep inelastic scattering (DIS of 160 GeV/c polarised muons off different polarised targets (NH3 for polarised protons and 6LiD for polarised deuterons. One of the main goals is to determine how the total longitudinal spin projection of the nucleon, 1/2, is distributed among its constituents, quarks and gluons. We review here the recent results on the quark and gluon helicities obtained by COMPASS, using a longitudinally polarised target. However, the understanding of the nucleon (spin structure based only on the parton helicities is not in any way complete. It basically provides us with a one-dimensional picture in a longitudinal momentum space. Therefore, COMPASS also studies the transverse momentum dependent parton distributions (TMDs with a transversely polarised target. Concerning the TMDs, the latest results on the Collins and Sivers asymmetries will be shown. The former is sensitive to the transverse spin structure of the nucleon, while the latter reﬂects the correlations between the quarks transverse momentum and the nucleon spin.
Nucleon Helicity and Transversity Parton Distributions from Lattice QCD
Chen, Jiunn-Wei; Ji, Xiangdong; Lin, Huey-Wen; Zhang, Jian-Hui
2016-01-01
We present the first lattice-QCD calculation of the isovector polarized parton distribution functions (both helicity and transversity) using the large-momentum effective field theory (LaMET) approach for direct Bjorken-$x$ dependence. We first review the detailed steps of the procedure in the unpolarized case, then generalize to the helicity and transversity cases. We also derive a new mass-correction formulation for all three cases. We then compare the effects of each finite-momentum correction using lattice data calculated at $M_\\pi\\approx 310$ MeV. Finally, we discuss the implications of these results for the poorly known antiquark structure and predict the sea-flavor asymmetry in the transversely polarized nucleon.
Stopped nucleons in configuration space
Bialas, Andrzej; Koch, Volker
2016-01-01
In this note, using the colour string model, we study the configuration space distribution of stopped nucleons in heavy-ion collisions. We find that the stopped nucleons from the target and the projectile end up separated from each other by the distance increasing with the collision energy. In consequence, for the center of mass energies larger than 6 or 10 GeV (depending on the details of the model) it appears that the system created is not in thermal and chemical equilibrium, and the net baryon density reached is likely not much higher than that already present in the colliding nuclei.
Studies of the dilepton emission from nucleon-nucleon interactions
Bacelar, JCS; Fujiwara, M; Shima, T
2002-01-01
real- and virtual-photon emission during interactions between few-nucleon systems have been investigated at KVI with a 190 MeV proton beam. Here I will concentrate the discussion on the results of the virtual-photon emission for the proton-proton system and proton-deuteron capture. Predictions of a
Nuclear effects on neutrino emissivities from nucleon-nucleon bremsstrahlung
Stoica, S.; Paun, V. P.; Negoita, A. G.
2004-06-01
The rates of neutrino pair emission by nucleon-nucleon (NN) bremsstrahlung are calculated with the inclusion of the full contribution from a nuclear one pion exchange potential (OPEP). We compute the contributions from the neutron-neutron (nn), proton-proton (pp), and neutron-proton (np) processes for physical conditions encountered in supernovae and neutron stars, both in the degenerate (D) and nondegenerate (ND) limits. We find a significant reduction of these rates, especially for the nn and pp processes, in comparison with the case when the whole nuclear contribution was replaced by constants, representing the high-momentum limits of the expressions of the nuclear potential. Furthermore, we also perform the calculations by including contributions due to the ρ meson exchange between nucleons, in the OPEP. This may be relevant for processes produced in the inner core of neutron stars, where the density may exceed several times the standard nuclear density, and the short-range part of the NN interaction should be taken into account. These corrections lead to an additional suppression of the neutrino emission rates between (8 and 36)%, depending on the process [nn (pp) or np] and physical conditions (temperature and degeneracy of the nucleons).
Hammer events, neutrino energies, and nucleon-nucleon correlations
Weinstein, L B; Piasetzky, E
2016-01-01
Neutrino oscillation measurements depend on a difference between the rate of neutrino-nucleus interactions at different neutrino energies or different distances from the source. Knowledge of the neutrino energy spectrum and neutrino-detector interactions are crucial for these experiments. Short range nucleon-nucleon correlations in nuclei (SRC) affect properties of nuclei. The ArgoNeut liquid Argon Time Projection Chamber (lArTPC) observed neutrino-argon scattering events with two protons back-to-back in the final state ("hammer" events) which they associated with SRC pairs. The MicroBoone lArTPC will measure far more of these events. We simulate hammer events using two simple models. We use the well-known electron-nucleon cross section to calculate e-argon interactions where the e- scatters from a proton, ejecting a pi+, and the pi+ is then absorbed on a moving deuteron-like $np$ pair. We also use a model where the electron excites a nucleon to a Delta, which then deexcites by interacting with a second nucle...
Electromagnetic Form Factors of the Nucleon
Bijker, R
1997-01-01
We reanalyze the world data on the electromagnetic form factors of the nucleon. The calculations are performed in the framework of an algebraic model of the nucleon combined with vector meson dominance.
Dispersion-theoretical analysis of the nucleon electromagnetic form factors
Energy Technology Data Exchange (ETDEWEB)
Belushkin, M.
2007-09-29
The structure of the proton and the neutron is of fundamental importance for the study of the strong interaction dynamics over a wide range of momentum transfers. The nucleon form factors encode information on the internal structure of the nucleon as probed by the electromagnetic interaction, and, to a certain extent, reflect the charge and magnetisation distributions within the proton and the neutron. In this thesis we report on our investigation of the electromagnetic form factors of the proton and the neutron with dispersion relation techniques, including known experimental input on the {pi}{pi}, K anti K and the {rho}{pi} continua and perturbative QCD constraints. We include new experimental data on the pion form factor and the nucleon form factors in our simultaneous analysis of all four form factors in both the space- and the timelike regions for all momentum transfers, and perform Monte- Carlo sampling in order to obtain theoretical uncertainty bands. Finally, we discuss the implications of our results on the pion cloud of the nucleon, the nucleon radii and the Okubo-Zweig-Iizuka rule, and present our results of a model-independent approach to estimating two-photon effects in elastic electron-proton scattering. (orig.)
Nuclear effects in the structure functions
Indian Academy of Sciences (India)
E Marco; E Oset; S K Singh
2003-11-01
By using a relativistic framework and accurate nuclear spectral function the structure functions 2 and 3 of deep inelastic charged lepton and neutrino scattering are calculated in nuclei and results are presented.
Precision nucleon-nucleon potential at fifth order in the chiral expansion
Epelbaum, E; Meißner, U -G
2014-01-01
We present a nucleon-nucleon potential at fifth order in chiral effective field theory. We find a substantial improvement in the description of nucleon-nucleon phase shifts as compared to the fourth-order results of Ref. [E. Epelbaum, H. Krebs, U.-G. Mei{\\ss}ner, arXiv:1412.0142 [nucl-th
The structure and function of cartilage proteoglycans
Directory of Open Access Journals (Sweden)
P J Roughley
2006-11-01
Full Text Available Cartilage contains a variety of proteoglycans that are essential for its normal function. These include aggrecan, decorin, biglycan, fibromodulin and lumican. Each proteoglycan serves several functions that are determined by both its core protein and its glycosaminoglycan chains. This review discusses the structure/function relationships of the cartilage proteoglycans, and the manner in which perturbations in proteoglycan structure or abundance can adversely affect tissue function.
$\\chi$EFT studies of few-nucleon systems: a status report
Energy Technology Data Exchange (ETDEWEB)
Schiavilla, Rocco [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)
2016-06-01
A status report on $\\chi$EFT studies of few-nucleon electroweak structure and dynamics is provided, including electromagnetic elastic form factors of few-nucleon systems, the $pp$ weak fusion and muon weak captures on deuteron and $^3$He, and a number of parity-violating processes induced by hadronic weak interactions.
P- and T-odd two-nucleon interaction and the deuteron electric dipole moment
Liu, CP; Timmermans, RGE
2004-01-01
The nuclear physics relevant to the electric dipole moment (EDM) of the deuteron is addressed. The general operator structure of the P- and T-odd nucleon-nucleon interaction is discussed and applied to the two-body contributions of the deuteron EDM, which can be calculated in terms of P- and T-odd m
Leading chiral logarithms for the nucleon mass
Energy Technology Data Exchange (ETDEWEB)
Vladimirov, Alexey A.; Bijnens, Johan [Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE 223 62 Lund (Sweden)
2016-01-22
We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the LLog series for the nucleon mass within the heavy baryon theory. The presented results are the first example of LLog calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass.
Polarized strangeness in the nucleon
Sapozhnikov, M G
2001-01-01
A large violation of the Okubo-Zweig-Iizuka rule was discovered in the annihilation of stopped antiprotons. The explanation of these experimental data is discussed in the framework of the model assumed that the nucleon strange sea quarks are polarized.
Exploring Proton Structure Using Lattice Qcd
Renner, D B
2004-01-01
We calculate moments of the generalized parton distributions of the nucleon using lattice QCD. The generalized parton distributions determine the angular momentum decomposition of the nucleon and the transverse distributions of partons within the nucleon. Additionally, the generalized parton distributions reduce to the elastic form factors and ordinary parton distributions in particular kinematic limits. Thus by calculating moments of the generalized parton distributions in lattice QCD we can explore many facets of the structure of the nucleon. In this effort, we have developed the building block method to determine all the lattice correlation functions which contribute to the off forward matrix elements of the twist two operators. These matrix elements determine the generalized form factors of the nucleon which in turn give the moments of the generalized parton distributions. Thus we use our building block method to calculate all the matrix elements of the lowest twist two operators. Furthermore, we use our ...
Photon structure function in supersymmetric QCD revisited
Energy Technology Data Exchange (ETDEWEB)
Sahara, Ryo, E-mail: sahara@scphys.kyoto-u.ac.jp [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Kyoto 606-8502 (Japan); Uematsu, Tsuneo, E-mail: uematsu@scphys.kyoto-u.ac.jp [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Kyoto 606-8502 (Japan); Kitadono, Yoshio, E-mail: kitadono@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Taipei, Taiwan (China)
2012-02-07
We investigate the virtual photon structure function in the supersymmetric QCD (SQCD), where we have squarks and gluinos in addition to the quarks and gluons. Taking into account the heavy particle mass effects to the leading order in QCD and SQCD we evaluate the photon structure function and numerically study its behavior for the QCD and SQCD cases.
Photon Structure Function in Supersymmetric QCD Revisited
Sahara, Ryo; Kitadono, Yoshio
2011-01-01
We investigate the virtual photon structure function in the supersymmetric QCD (SQCD), where we have squarks and gluinos in addition to the quarks and gluons. Taking into account the heavy particle mass effects to the leading order in QCD and SQCD we evaluate the photon structure function and numerically study its behavior for the QCD and SQCD cases.
Nuclear medium modification of the F{sub 2}(x,Q{sup 2}) structure function
Energy Technology Data Exchange (ETDEWEB)
Sajjad Athar, M., E-mail: sajathar@gmail.co [Department of Physics, Aligarh Muslim University, Aligarh 202 002 (India); Ruiz Simo, I.; Vicente Vacas, M.J. [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia - CSIC, 46100 Burjassot (Valencia) (Spain)
2011-05-01
We study the nuclear effects in the electromagnetic structure function F{sub 2}(x,Q{sup 2}) in the deep inelastic lepton-nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations. The ratios R{sub F}{sub 2}{sup A}(x,Q{sup 2})=(2F{sub 2}{sup A}(x,Q{sup 2}))/(AF{sub 2}{sup D}(x,Q{sup 2})) are obtained and compared with recent JLab results for light nuclei with special attention to the slope of the x distributions. This magnitude shows a non-trivial A dependence and it is insensitive to possible normalization uncertainties. The results have also been compared with some of the older experiments using intermediate mass nuclei.
WAY TO DETERMINE STIFFNESS FUNCTION OF STRUCTURE
Institute of Scientific and Technical Information of China (English)
WANG De-ming; GAI Bing-zheng
2005-01-01
For calculating the stiffness function of a structure, the differential equation of the vibration of the structure was divided into the differential equation on the original stiffness function that was known, and Fredholm integral equation of the first kind on the undetermined stiffness function that was unknown. And the stable solutions of the integral equation, when the smooth factor was equal to zero, was solved by the extrapolation with p smooth factors. So the stiffness function of the structure is obtained. Applied examples show that the method is feasible and effective.
Longitudinal-Transverse Separation of Deep-Inelastic Scattering at Low Q² on Nucleons and Nuclei
Energy Technology Data Exchange (ETDEWEB)
Tvaskis, Vladas
2004-12-09
Since the early experiments at SLAC, which discovered the nucleon substructure and led to the development of the quark parton model, deep inelastic scattering (DIS) has been the most powerful tool to investigate the partonic substructure of the nucleon. After about 30 years of experiments with electron and muon beams the nucleon structure function F{sub 2}(x,Q{sup 2}) is known with high precision over about four orders of magnitude in x and Q{sup 2}. In the region of Q{sup 2} > 1 (GeV/c){sup 2} the results of the DIS measurements are interpreted in terms of partons (quarks and gluons). The theoretical framework is provided in this case by perturbative Quantum Chromo Dynamics (pQCD), which includes scaling violations, as described by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations. The description starts to fail when Q{sup 2} becomes of the order of 1 (GeV/c){sup 2}, where non-perturbative effects (higher-twist effects), which are still not fully understood, become important (non-pQCD). The sensitivity for order-n twist effects increases with decreasing Q{sup 2}, since they include a factor 1/(Q{sup 2}{sup n}) (n {ge} 1).
Longitudinal-Transverse Separation of Deep-Inelastic Scattering at Low Q² on Nucleons and Nuclei
Energy Technology Data Exchange (ETDEWEB)
Tvaskis, Vladas [Vrije Univ., Amsterdam (Netherlands)
2004-12-06
Since the early experiments at SLAC, which discovered the nucleon substructure and led to the development of the quark parton model, deep inelastic scattering (DIS) has been the most powerful tool to investigate the partonic substructure of the nucleon. After about 30 years of experiments with electron and muon beams the nucleon structure function F_{2}(x,Q^{2}) is known with high precision over about four orders of magnitude in x and Q^{2}. In the region of Q^{2} > 1 (GeV/c)^{2} the results of the DIS measurements are interpreted in terms of partons (quarks and gluons). The theoretical framework is provided in this case by perturbative Quantum Chromo Dynamics (pQCD), which includes scaling violations, as described by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations. The description starts to fail when Q^{2} becomes of the order of 1 (GeV/c)^{2}, where non-perturbative effects (higher-twist effects), which are still not fully understood, become important (non-pQCD). The sensitivity for order-n twist effects increases with decreasing Q^{2}, since they include a factor 1/(Q^{2n}) (n ≥ 1).
Spin Structure Functions of the Deuteron Measured with CLAS in and above the Resonance Region
Energy Technology Data Exchange (ETDEWEB)
Dharmawardane, Kahanawita [Old Dominion Univ., Norfolk, VA (United States)
2004-05-01
Spin structure functions of the nucleon in the region of large x and small to moderate Q^{2} continue to be of high current interest. The first moment of the spin structure function g_{1}, γ_{1}, goes through a rapid transition from the photon point (Q^{2}=0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. The interesting behavior in the transition region is dominated by baryon resonance excitations. We concluded an experiment to measure these observables for deuterium as part of the ''EG1'' run group in Jefferson Lab's Hall B. We used a highly polarized electron beam with energies from 1.6 GeV to 5.7 GeV and a cryogenic polarized ND_{3} target together with the CEBAF Large Acceptance Spectrometer (CLAS) to accumulate over 11 billion events. In this thesis, we present results for the spin structure function g$d\\atop{1}$ (x,Q^{2}), as well as its first moment, γ$d\\atop{1}$(Q^{2}) in and above the resonance region over a Q^{2} range from 0.05 to 5 Gev^{2}, based on the data taken with beam energies of 1.6 and 5.7 GeV. We also extract the behavior of A$d\\atop{1}$(x) at large x. Our data are consistent with the Hyperfine-perturbed quark model calculation which predicts that A$d\\atop{1}$ (x → 1) → 1. We also see evidence for duality in g$d\\atop{1}$ (x, Q^{2}) at Q^{2} > GeV^{2}.
Quantal Nucleon Diffusion I: Central Collisions of Symmetric Nuclei
Ayik, S; Yilmaz, B; Umar, A S
2016-01-01
Quantal diffusion mechanism of nucleon exchange is studied in the central collisions of several symmetric heavy-ion collisions in the framework of the Stochastic Mean-Field (SMF) approach. Since at bombarding energies below the fusion barrier, di-nuclear structure is maintained, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Quantal diffusion coefficients, including memory effects, for proton and neutron exchanges are extracted microscopically employing the SMF approach. The quantal calculations of neutron and proton variances are compared with the semi-classical results.
Open and Hidden Strangeness Production in Nucleon-Nucleon Collisions
Shyam, Radhey
2008-01-01
We present an overview of the description of K and eta meson productions in nucleon-nucleon collisions within an effective Lagrangian model where meson production proceeds via excitation, propagation and subsequent decay of intermediate baryonic resonant states. The $K$ meson contains a strange quark ($s$) or antiquark ($\\bar s$) while the $\\eta$ meson has hidden strangeness as it contains some component of the $s{\\bar s}$ pair. Strange meson production is expected to provide information on the manifestation of quantum chromodynamics in the non-perturbative regime of energies larger than that of the low energy pion physics. We discuss specific examples where proper understanding of the experimental data for these reactions is still lacking.
Leader, Elliot; Stamenov, Dimiter B
2010-01-01
In a recent analysis of the world data on polarized DIS, Blumlein and Bottcher conclude that there is no evidence for higher twist contributions, in contrast to the claim of the LSS group, who find evidence for significant higher twist effects. We explain the origin of the apparent contradiction between these results.
Nucleon matrix elements using the variational method in lattice QCD
Dragos, Jack; Kamleh, Waseem; Leinweber, Derek B; Nakamura, Yoshifumi; Rakow, Paul E L; Schierholz, Gerrit; Young, Ross D; Zanotti, James M
2016-01-01
The extraction of hadron matrix elements in lattice QCD using the standard two- and three-point correlator functions demands careful attention to systematic uncertainties. One of the most commonly studied sources of systematic error is contamination from excited states. We apply the variational method to calculate the axial vector current $g_{A}$, the scalar current $g_{S}$ and the quark momentum fraction $\\left$ of the nucleon and we compare the results to the more commonly used summation and two-exponential fit methods. The results demonstrate that the variational approach offers a more efficient and robust method for the determination of nucleon matrix elements.
Nucleon Emision Off Nuclei Induced By Neutrino Interactions
Valverde, M; Amaro, J E; Vicente-Vacas, M J
2009-01-01
We make a review of the main nuclear effects that affect neutrino-nucleus cross sections. We discuss how the different models in the literature try to describe these different effects, and thus try to compare between them. We focus on the quasi-elastic reaction in the neutrino energy region of around 1 GeV, where recent data from MiniBoone are available. Among the issues discussed are the different treatment of medium corrections to initial and nal state nucleon wave functions and the problem of the rescattering of ejected nucleons.
Nucleon axial and tensor charges with dynamical overlap quarks
Yamanaka, N; Hashimoto, S; Kaneko, T
2015-01-01
We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the all-mode-averaging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the all-to-all quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses $m_\\pi$ = 450 and 540 MeV.
Structure and function in flow networks
Rubido, Nicolás; Baptista, Murilo S
2013-01-01
This Letter presents a unified approach for the fundamental relationship between structure and function in flow networks by solving analytically the voltages in a resistor network, transforming the network structure to an effective all-to-all topology, and then measuring the resultant flows. Moreover, it defines a way to study the structural resilience of the graph and to detect possible communities.
Nitrogenase structure and function relationships by density functional theory.
Harris, Travis V; Szilagyi, Robert K
2011-01-01
Modern density functional theory has tremendous potential with matching popularity in metalloenzymology to reveal the unseen atomic and molecular details of structural data, spectroscopic measurements, and biochemical experiments by providing insights into unobservable structures and states, while also offering theoretical justifications for observed trends and differences. An often untapped potential of this theoretical approach is to bring together diverse experimental structural and reactivity information and allow for these to be critically evaluated at the same level. This is particularly applicable for the tantalizingly complex problem of the structure and molecular mechanism of biological nitrogen fixation. In this chapter we provide a review with extensive practical details of the compilation and evaluation of experimental data for an unbiased and systematic density functional theory analysis that can lead to remarkable new insights about the structure-function relationships of the iron-sulfur clusters of nitrogenase.
Form factors in an algebraic model of the nucleon
Bijker, R
1995-01-01
We study the electromagnetic form factors of the nucleon in a collective model of baryons. In an algebraic approach to hadron structure, we derive closed expressions for both elastic and transition form factors, and consequently for the helicity amplitudes that can be measured in electro- and photoproduction.
Measurement of the proton structure function F2 at low Q2 in QED Compton scattering at HERA
Energy Technology Data Exchange (ETDEWEB)
Aktas, A. [DESY, Hamburg (Germany); Andreev, V. [Lebedev Physical Institute, Moscow (Russian Federation); Anthonis, T. [Inter-University Institute for High Energies ULB-VUB, Brussels, Universiteit Antwerpen, Antwerpen (Belgium)] (and others)
2004-09-30
The proton structure function F2(x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q2, down to 0.5 GeV{sup 2}, and Bjorken x up to {approx}0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton-nucleon scattering experiments.
Measurement of the proton structure function F2 at low Q2 in QED Compton scattering at HERA
Aktas, A.; Andreev, V.; Anthonis, T.; Asmone, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Berndt, T.; Bizot, J. C.; Böhme, J.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brisson, V.; Bröker, H.-B.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Chekelian, V.; Collard, C.; Contreras, J. G.; Coppens, Y. R.; Coughlan, J. A.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E. A.; Diaconu, C.; Dingfelder, J.; Dodonov, V.; Dubak, A.; Duprel, C.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Flügge, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garutti, E.; Garvey, J.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gorbounov, S.; Grab, C.; Grässler, H.; Greenshaw, T.; Gregori, M.; Grindhammer, G.; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Heremans, R.; Herrera, G.; Herynek, I.; Heuer, R.-D.; Hildebrandt, M.; Hiller, K. H.; Höting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keller, N.; Kennedy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Koblitz, B.; Korbel, V.; Kostka, P.; Koutouev, R.; Kropivnitskaya, A.; Kroseberg, J.; Kückens, J.; Kuhr, T.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebedev, A.; Leißner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lueders, H.; Lüke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marks, J.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Michine, S.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morozov, I.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Ossoskov, G.; Ozerov, D.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Plačakytė, R.; Pöschl, R.; Portheault, B.; Povh, B.; Raicevic, N.; Ratiani, Z.; Reimer, P.; Reisert, B.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Scheins, J.; Schilling, F.-P.; Schleper, P.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Uraev, A.; Urban, M.; Usik, A.; Utkin, D.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Winter, G.-G.; Wissing, Ch.; Woehrling, E.-E.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zohrabyan, H.; Zomer, F.; H1 Collaboration
2004-09-01
The proton structure function F2 (x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q2, down to 0.5 GeV2, and Bjorken x up to ∼0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton-nucleon scattering experiments.
Nucleon Polarizibilities for Virtual Photons
Edelmann, J; Piller, G; Weise, W
1998-01-01
We generalize the sum rules for the nucleon electric plus magnetic polarizability $\\Sigma=\\alpha+\\beta$ and for the nucleon spin-polarizability sections are represented in our calculation by one-pion-loop graphs of relativistic baryon chiral perturbation theory and the $\\Delta(1232)$-resonance excitation. For the proton we find good agreement of the calculated electroproduction data for $Q^2<0.4 GeV^2$. The proton spin-polarizability "partonic" curve, extracted from polarized deep-inelastic scattering, around $Q^2=0.7 GeV^2$. For the neutron our predictions of $\\Sigma_n(Q^2)$ and Upcoming (polarized) electroproduction experiments will be able to test the generalized polarizability sum rules investigated here.
Study of the derivative expansions for the nuclear structure functions
Simo, I Ruiz
2008-01-01
We study the convergence of the series expansions sometimes used in the analysis of the nuclear effects in Deep Inelastic Scattering (DIS) proccesses induced by leptons. The recent advances in statistics and quality of the data, in particular for neutrinos calls for a good control of the theoretical uncertainties of the models used in the analysis. Using realistic nuclear spectral functions which include nucleon correlations, we find that the convergence of the derivative expansions to the full results is poor except at very low values of $x$.
Nuclear medium effects in $F_{2A}^{EM}(x,Q^2)$ and $F_{2A}^{Weak}(x,Q^2)$ structure functions
Haider, H; Athar, M Sajjad; Singh, S K; Simo, I Ruiz
2016-01-01
Recent phenomenological analysis of experimental data on DIS processes induced by charged leptons and neutrinos/antineutrinos beams on nuclear targets by CTEQ collaboration has confirmed the observation of CCFR and NuTeV collaborations, that weak structure function $F_{2A}^{Weak} (x,Q^2)$ is different from electromagnetic structure function $F_{2A}^{EM} (x,Q^2)$ in a nucleus like iron, specially in the region of low $x$ and $Q^2$. In view of this observation we have made a study of nuclear medium effects on $F_{2A}^{Weak} (x,Q^2)$ and $F_{2A}^{EM} (x,Q^2)$ for a wide range of $x$ and $Q^2$ using a microscopic nuclear model. We have considered Fermi motion, binding energy, nucleon correlations, mesonic contributions from pion and rho mesons and shadowing effects to incorporate nuclear medium effects. The calculations are performed in a local density approximation using a relativistic nucleon spectral function which includes nucleon correlations. The numerical results in the case of iron nucleus are compared wi...
Amir-Ahmadi, H. R.; Castelijns, R.; Deltuva, A.; Eslami-Kalantari, M.; Garderen, E. D. Van; Harakeh, M. N.; Kalantar-Nayestanaki, N.; Kiš, M.; Löhner, H.; Mahjour-Shafiei, M.; Mardanpour, H.; Messchendorp, J. G.; Mukherjee, B.; Savran, D.; Sekiguchi, K.; Shende, S. V.; Witała, H.; Wörtche, H. J.
2007-04-01
The cross section and several spin-dependent observables have been measured with high precision for the reaction H(d→,p→)d at 90 MeV/nucleon. Several calculations were performed based either purely on two-nucleon potentials or also including three-nucleon potentials (3NP). The cross sections are consistent with all calculations including 3NPs. However, no single calculation reproduces the analyzing powers and spin-transfer coefficients, although some spin observables are reproduced to various degrees by the different calculations. A good understanding of the spin structure of 3NP is still lacking.
Parton Distributions in Nucleon on the Basis of a Relativistic Independent Quark Model
Barik, N
2001-01-01
At a low resolution scale with $Q^2={\\mu}^2$ corresponding to the nucleon bound state; deep inelastic unpolarized structure functions $F_1(x,{\\mu}^2)$ and $F_2(x,{\\mu}^2)$ are derived with correct support using the symmetric part of the hadronic tensor under some simplifying assumptions in the Bjorken limit. For doing this; the nucleon in its ground state has been represented by a suitably constructed momentum wave packet of its valence quarks in their appropriate SU(6) spin flavor configuration with the momentum probability amplitude taken phenomenologically in reference to the independent quark model of scalar-vector harmonic potential. The valence quark distribution functions $u_v(x,{\\mu}^2)$ and $d_v(x,{\\mu}^2)$, extracted from the structure function $F_1(x,{\\mu}^2)$ in a parton model interpretation, satisfy normalization constraints as well as the momentum sum-rule requirements at a bound state scale of ${\\mu}^2=0.1 GeV^2$. QCD evolution of these distribution functions taken as the inputs; yields at $Q_0...
Progress on nuclear modifications of structure functions
Kumano, S
2016-01-01
We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrino-oscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function $b_1$ is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact ...
Structural and functional properties of designed globins
Indian Academy of Sciences (India)
Yasuhiro Isogai; Anna Ishii; Manabu Ishida; Masahiro Mukai; Motonori Ota; Ken Nishikawa; Tetsutaro Iizuka
2000-06-01
De novo design of artificial proteins is an essential approach to elucidate the principles of protein architecture and to understand specific functions of natural proteins and also to yield novel molecules for medical and industrial aims. We have designed artificial sequences of 153 amino acids to fit the main-chain framework of the sperm whale myoglobin structure based on the knowledge-based energy functions to evaluate the compatibility between protein tertiary structures and amino acid sequences. The synthesized artificial globins bind a single heme per protein molecule as designed, which show well-defined electrochemical and spectroscopic features characteristic of proteins with a low-spin heme. Redox and ligand binding reactions of the artificial heme proteins were investigated and these heme-related functions were found to vary with their structural uniqueness. Relationships between the structural and functional properties are discussed.
Can the 4He experiments serve as a database for determining the three-nucleon force?
Hofmann, H M; Hale, Gerald M.; Hofmann, Hartmut M.
2005-01-01
We report on microscopic calculations for the 4He compound system in the framework of the resonating group model employing realistic nucleon-nucleon and three nucleon forces. The resulting scattering phase shifts are compared to those of a comprehensive R-matrix analysis of all data in this system, which are available in numerical form. The agreement between calculation and analysis is in most cases very good. Adding three-nucleon forces yields in many cases large effects. For a few cases the new agreement is striking. We relate some differencies between calculation and analysis to specific data and discuss neccessary experiments to clarify the situation. From the results we conclude that the data of the 4He system might be well suited to determine the structure of the three-nucleon force.
Understanding Microbial Communities: Function, Structure and Dynamics
2015-02-11
microbial communities: Function, structure and dynamics’, at the Isaac Newton Institute, University of Cambridge, United Kingdom, from August to...dynamics’, at the Isaac Newton Institute, University of Cambridge, United Kingdom, from August to December 2014. The programme involved over 150...Communities: Function, Structure and Dynamics’, at the Isaac Newton Institute, Cambridge University, UK, from 19th August 2014 – 19th December 2014
Recent Structure Function Results from CCFR
Fleming, B T; Alton, A; Arroyo, C G; Avvakumov, S; De Barbaro, L; De Barbaro, P; Bazarko, A O; Bernstein, R H; Bodek, Arie; Bolton, T; Brau, J E; Buchholz, D; Budd, H S; Bugel, L; Conrad, J; Drucker, R B; Formaggio, J A; Frey, R; Goldman, J; Goncharov, M; Harris, D A; Johnson, R A; Kim, J H; King, B J; Kinnel, T; Koutsoliotas, S; Lamm, M J; Marsh, W; Mason, D; McFarland, K S; McNulty, C; Mishra, S R; Naples, D; Nienaber, P; Romosan, A; Sakumoto, W K; Schellman, H; Sciulli, F J; Seligman, W G; Shaevitz, M H; Smith, W H; Spentzouris, P; Stern, E G; Vakili, M; Vaitaitis, A G; Yang, U K; Yu, J; Zeller, G P; Zimmerman, E D
2000-01-01
A new structure function analysis of CCFR deep inelastic nu-N and nubar-N scattering data is presented for previously unexplored kinematic regions down to Bjorken x=0.0045 and Q^2=0.3 GeV^2. Comparisons to charged lepton scattering data from NMC and E665 experiments are made and the behavior of the structure function F2_nu is studied in the limit Q^2 -> 0
Polarized deuteron structure functions at small x
Edelmann, J; Weise, W
1997-01-01
We investigate shadowing corrections to the polarized deuteron structure functions g_1^d and b_1. In the kinematic domain of current fixed target experiments we observe that shadowing effects in g_1^d are approximately twice as large as for the unpolarized structure function F_2^d. Furthermore, we find that b_1 is surprisingly large at x < 0.1 and receives dominant contributions from coherent double scattering.
General aspects of the nucleon-nucleon interaction and nuclear matter properties
Energy Technology Data Exchange (ETDEWEB)
Plohl, Oliver
2008-07-25
The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are
[Snake venom metalloproteinases: structure, biosynthesis and function(s)].
Limam, I; El Ayeb, M; Marrakchi, N
2010-01-01
The biochemical and the pharmacological characterization of snake venoms revealed an important structural and functional polymorphism of proteins which they contain. Among them, snake venom metalloproteases (SVMPs) constitute approximatively 20 to 60% of the whole venom proteins. During the last decades, a significant progress was performed against structure studies and the biosynthesis of the SVMPs. Indeed, several metalloproteases were isolated and characterized against their structural and pharmacological properties. In this review, we report the most important properties concerning the classification, the structure of the various domains of the SVMPs as well as their biosynthesis and their activities as potential therapeutic agents.
Fujiwara, Y; Kohno, M; Suzuki, Y
2004-01-01
Quark-model nucleon-nucleon and hyperon-nucleon interactions by the Kyoto- Niigata group are applied to the hypertriton calculation in a new three-cluster Faddeev formalism using the two-cluster resonating-group method kernels. The most recent model, fss2, gives a reasonable result similar to the Nijmegen soft-core model NSC89, except for an appreciable contributions of higher partial waves.
Zinc finger structure-function in Ikaros
Institute of Scientific and Technical Information of China (English)
Marvin; A; Payne
2011-01-01
The zinc finger motif was used as a vehicle for the initial discovery of Ikaros in the context of T-cell differentiation and has been central to all subsequent analyses of Ikaros function.The Ikaros gene is alternately spliced to produce several isoforms that confer diversity of function and consequently have complicated analysis of the function of Ikaros in vivo.Key features of Ikaros in vivo function are associated with six C2H2 zinc fingers;four of which are alternately incorporated in the production of the various Ikaros isoforms.Although no complete structures are available for the Ikaros protein or any of its family members,considerable evidence has accumulated about the structure of zinc fingers and the role that this structure plays in the functions of the Ikaros family of proteins.This review summarizes the structural aspects of Ikaros zinc fingers,individually,and in tandem to provide a structural context for Ikaros function and to provide a structural basis to inform the design of future experiments with Ikaros and its family members.
Next-order structure-function equations
Hill, Reginald J.; Boratav, Olus N.
2001-01-01
Kolmogorov's equation [Dokl. Akad. Nauk SSSR 32, 16 (1941)] relates the two-point second- and third-order velocity structure functions and the energy dissipation rate. The analogous next higher-order two-point equation relates the third- and fourth-order velocity structure functions and the structure function of the product of pressure-gradient difference and two factors of velocity difference, denoted Tijk. The equation is simplified on the basis of local isotropy. Laboratory and numerical simulation data are used to evaluate and compare terms in the equation, examine the balance of the equation, and evaluate components of Tijk. Atmospheric surface-layer data are used to evaluate Tijk in the inertial range. Combined with the random sweeping hypothesis, the equation relates components of the fourth-order velocity structure function. Data show the resultant error of this application of random sweeping. The next-order equation constrains the relationships that have been suggested among components of the fourth-order velocity structure function. The pressure structure function, pressure-gradient correlation, and mean-squared pressure gradient are related to Tijk. Inertial range formulas are discussed.
Structure and Structure-activity Relationship of Functional Organic Molecules
Institute of Scientific and Technical Information of China (English)
2011-01-01
@@ Research theme The group is made up of junior scientists from the State Key Laboratory of Elemento-organic Chemistry, Nankai University.The scientists focus their studis on the structure and structure-activity relationship of functional organic molecules not only because it has been the basis of their research, but also because the functional study of organic compounds is now a major scientific issue for organic chemists around the world.
A Realistic Description of Nucleon-Nucleon and Hyperon-Nucleon Interactions in the SU_6 Quark Model
Fujiwara, Y; Kohno, M; Nakamoto, C; Suzuki, Y
2001-01-01
We upgrade a SU_6 quark-model description for the nucleon-nucleon and hyperon-nucleon interactions by improving the effective meson-exchange potentials acting between quarks. For the scalar- and vector-meson exchanges, the momentum-dependent higher-order term is incorporated to reduce the attractive effect of the central interaction at higher energies. The single-particle potentials of the nucleon and Lambda, predicted by the G-matrix calculation, now have proper repulsive behavior in the momentum region q_1=5 - 20 fm^-1. A moderate contribution of the spin-orbit interaction from the scalar-meson exchange is also included. As to the vector mesons, a dominant contribution is the quadratic spin-orbit force generated from the rho-meson exchange. The nucleon-nucleon phase shifts at the non-relativistic energies up to T_lab=350 MeV are greatly improved especially for the 3E states. The low-energy observables of the nucleon-nucleon and the hyperon-nucleon interactions are also reexamined. The isospin symmetry break...
Measurements of the longitudinal structure function and |$V_{cs}$| in the CCFR experiment
Yang, U K; Arroyo, C G; Bazarko, A O; Bernstein, R H; Bodek, Arie; Bolton, T; Budd, H S; Conrad, J; Harris, D A; Johnson, R A; Kim, J H; King, B J; Kinnel, T; Lamm, M J; Lefmann, W C; Marsh, W; McFarland, K S; Mishra, S R; Naples, D; Quintas, P Z; Romosan, A; Sakumoto, W K; Schellman, H; Sciulli, F J; Seligman, W G; Shaevitz, M H; Smith, W H; Spentzouris, P; Stern, E G; Vakili, M
1998-01-01
Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F_2, xF_3(nu), xF_3(nubar) and R(longitudinal) in the kinematic region 0.01
Huntington's disease : functional and structural biomarkers
Dumas, Eve Marie
2012-01-01
The aims of this thesis were to gain insight into specific disease processes in Huntington’s Disease (HD) and to identify biomarkers. To achieve these aims, cognitive functioning, structural brain characteristics and intrinstic functional brain connectivity of premanifest and early HD subjects were
2004 Structural, Function and Evolutionary Genomics
Energy Technology Data Exchange (ETDEWEB)
Douglas L. Brutlag Nancy Ryan Gray
2005-03-23
This Gordon conference will cover the areas of structural, functional and evolutionary genomics. It will take a systematic approach to genomics, examining the evolution of proteins, protein functional sites, protein-protein interactions, regulatory networks, and metabolic networks. Emphasis will be placed on what we can learn from comparative genomics and entire genomes and proteomes.
Structure functions in the chiral bag model
Energy Technology Data Exchange (ETDEWEB)
Sanjose, V.; Vento, V.
1989-07-13
We calculate the structure functions of an isoscalar nuclear target for the deep inelastic scattering by leptons in an extended version of the chiral bag model which incorporates the qanti q structure of the pions in the cloud. Bjorken scaling and Regge behavior are satisfied. The model calculation reproduces the low-x behavior of the data but fails to explain the medium- to large-x behavior. Evolution of the quark structure functions seem inevitable to attempt a connection between the low-energy models and the high-energy behavior of quantum chromodynamics. (orig.).
Negative-parity nucleon excited state in nuclear matter
Ohtani, Keisuke; Gubler, Philipp; Oka, Makoto
2016-10-01
Spectral functions of the nucleon and its negative-parity excited state in nuclear matter are studied by using QCD sum rules and the maximum entropy method (MEM). It is found that in-medium modifications of the spectral functions are attributed mainly to density dependencies of the and condensates. The MEM reproduces the lowest-energy peaks of both the positive- and negative-parity nucleon states at finite density up to ρ ˜ρN (normal nuclear matter density). As the density grows, the residue of the nucleon ground state decreases gradually while the residue of the lowest negative-parity excited state increases slightly. On the other hand, the positions of the peaks, which correspond to the total energies of these states, are almost density independent for both parity states. The density dependencies of the effective masses and vector self-energies are also extracted by assuming phenomenological mean-field-type propagators for the peak states. We find that, as the density increases, the nucleon effective mass decreases while the vector self-energy increases. The density dependence of these quantities for the negative-parity state on the other hand turns out to be relatively weak.
Database of Nucleon-Nucleon Scattering Cross Sections by Stochastic Simulation Project
National Aeronautics and Space Administration — A database of nucleon-nucleon elastic differential and total cross sections will be generated by stochastic simulation of the quantum Liouville equation in the...
Dissecting nucleon transition electromagnetic form factors
Segovia, Jorge
2016-01-01
In Poincar\\'e-covariant continuum treatments of the three valence-quark bound-state problem, the force behind dynamical chiral symmetry breaking also generates nonpointlike, interacting diquark correlations in the nucleon and its resonances. We detail the impact of these correlations on the electromagnetically-induced nucleon-$\\Delta$ and nucleon-Roper transitions, providing a flavour-separation of the latter and associated predictions that can be tested at modern facilities.
Predicting protein structure classes from function predictions
DEFF Research Database (Denmark)
Sommer, I.; Rahnenfuhrer, J.; de Lichtenberg, Ulrik;
2004-01-01
We introduce a new approach to using the information contained in sequence-to-function prediction data in order to recognize protein template classes, a critical step in predicting protein structure. The data on which our method is based comprise probabilities of functional categories; for given...... query sequences these probabilities are obtained by a neural net that has previously been trained on a variety of functionally important features. On a training set of sequences we assess the relevance of individual functional categories for identifying a given structural family. Using a combination...... of the most relevant categories, the likelihood of a query sequence to belong to a specific family can be estimated. Results: The performance of the method is evaluated using cross-validation. For a fixed structural family and for every sequence, a score is calculated that measures the evidence for family...
Magnetism and Structure in Functional Materials
Planes, Antoni; Saxena, Avadh
2005-01-01
Magnetism and Structure in Functional Materials addresses three distinct but related topics: (i) magnetoelastic materials such as magnetic martensites and magnetic shape memory alloys, (ii) the magnetocaloric effect related to magnetostructural transitions, and (iii) colossal magnetoresistance (CMR) and related magnanites. The goal is to identify common underlying principles in these classes of materials that are relevant for optimizing various functionalities. The emergence of apparently different magnetic/structural phenomena in disparate classes of materials clearly points to a need for common concepts in order to achieve a broader understanding of the interplay between magnetism and structure in this general class of new functional materials exhibiting ever more complex microstructure and function. The topic is interdisciplinary in nature and the contributors correspondingly include physicists, materials scientists and engineers. Likewise the book will appeal to scientists from all these areas.
Clustering aspects in nuclear structure functions
Hirai, M; Saito, K; Watanabe, T
2010-01-01
For understanding an anomalous nuclear effect experimentally observed for the beryllium-9 nucleus at the Thomas Jefferson National Accelerator Facility (JLab), clustering aspects are studied in structure functions of deep inelastic lepton-nucleus scattering by using momentum distributions calculated in antisymmetrized (or fermionic) molecular dynamics (AMD) and also in a simple shell model for comparison. According to the AMD, the Be-9 nucleus consists of two alpha-like clusters with a surrounding neutron. The clustering produces high-momentum components in nuclear wave functions, which affects nuclear modifications of the structure functions. We investigated whether clustering features could appear in the structure function F_2 of Be-9 along with studies for other light nuclei. We found that nuclear modifications of F_2 are similar in both AMD and shell models within our simple convolution description although there are slight differences in Be-9. It indicates that the anomalous Be-9 result should be explain...
The proteome: structure, function and evolution.
Fleming, Keiran; Kelley, Lawrence A; Islam, Suhail A; MacCallum, Robert M; Muller, Arne; Pazos, Florencio; Sternberg, Michael J E
2006-03-29
This paper reports two studies to model the inter-relationships between protein sequence, structure and function. First, an automated pipeline to provide a structural annotation of proteomes in the major genomes is described. The results are stored in a database at Imperial College, London (3D-GENOMICS) that can be accessed at www.sbg.bio.ic.ac.uk. Analysis of the assignments to structural superfamilies provides evolutionary insights. 3D-GENOMICS is being integrated with related proteome annotation data at University College London and the European Bioinformatics Institute in a project known as e-protein (http://www.e-protein.org/). The second topic is motivated by the developments in structural genomics projects in which the structure of a protein is determined prior to knowledge of its function. We have developed a new approach PHUNCTIONER that uses the gene ontology (GO) classification to supervise the extraction of the sequence signal responsible for protein function from a structure-based sequence alignment. Using GO we can obtain profiles for a range of specificities described in the ontology. In the region of low sequence similarity (around 15%), our method is more accurate than assignment from the closest structural homologue. The method is also able to identify the specific residues associated with the function of the protein family.
Moments of F{sub 2} Structure Functions and Multiparton Correlations in Nuclei
Energy Technology Data Exchange (ETDEWEB)
Mikhail Osipenko
2002-10-01
The inclusive inelastic electron scattering o the proton was measured at five different beam energies 1.5, 2.5, 4.0, 4.2 and 4.4 GeV. The data were taken, during February-March 1999, on a liquid hydrogen target with the CLAS detector installed in Hall-B of the Thomas Jefferson National Accelerator Facility (TJNAF). The obtained high statistics and high precision data appear to be in good agreement with previously measured world data and permit to integrate experimental values of F{sub 2} over x at fixed Q{sup 2} , allowing for the first time the evaluation of its experimental moments at low and moderate values of Q{sup 2} . In a combined analysis of CLAS and world data, the Q{sup 2} -evolution of the experimental moments was explored in the range from 0.3 up to 100 GeV{sup 2} . This offered a unique possibility to trace changes of the proton structure function from hard DIS down to the non-perturbative regime through the transition region, which is of particular interest for the TJNAF physics program. The obtained experimental moments allowed to perform a separation between the leading twist, calculable in the framework of the perturbative QCD (pQCD), and higher twists, treated effectively. A comparison with theoretical predictions based either on lattice QCD simulations or obtained within models of the nucleon structure may represent an important test of our understanding of the nucleon structure as observed at large wavelengths.
Moments of F_{2} Structure Functions and Multiparton Correlations in Nuclei
Energy Technology Data Exchange (ETDEWEB)
Osipenko, Mikhail [Moscow State Univ., Moscow (Russian Federation)
2002-10-01
The inclusive inelastic electron scattering o the proton was measured at five different beam energies 1.5, 2.5, 4.0, 4.2 and 4.4 GeV. The data were taken, during February-March 1999, on a liquid hydrogen target with the CLAS detector installed in Hall-B of the Thomas Jefferson National Accelerator Facility (TJNAF). The obtained high statistics and high precision data appear to be in good agreement with previously measured world data and permit to integrate experimental values of F_{2} over x at fixed Q^{2} , allowing for the first time the evaluation of its experimental moments at low and moderate values of Q^{2} . In a combined analysis of CLAS and world data, the Q^{2}-evolution of the experimental moments was explored in the range from 0.3 up to 100 GeV^{2} . This offered a unique possibility to trace changes of the proton structure function from hard DIS down to the non-perturbative regime through the transition region, which is of particular interest for the TJNAF physics program. The obtained experimental moments allowed to perform a separation between the leading twist, calculable in the framework of the perturbative QCD (pQCD), and higher twists, treated effectively. A comparison with theoretical predictions based either on lattice QCD simulations or obtained within models of the nucleon structure may represent an important test of our understanding of the nucleon structure as observed at large wavelengths.
Structure and Functions of Linker Histones.
Lyubitelev, A V; Nikitin, D V; Shaytan, A K; Studitsky, V M; Kirpichnikov, M P
2016-03-01
Linker histones such as variants H1, H5, and other similar proteins play an important role in regulation of chromatin structure and dynamics. However, interactions of linker histones with DNA and proteins, as well as specific functions of their different variants, are poorly studied. This is because they acquire tertiary structure only when interacting with a nucleosome, and because of limitations of currently available methods. However, deeper investigation of linker histones and their interactions with other proteins will address a number of important questions - from structure of compacted chromatin to regulation of early embryogenesis. In this review, structures of histone H1 variants and its interaction with chromatin DNA are considered. A possible functional significance of different H1 variants, a role of these proteins in maintaining interphase chromatin structure, and interactions of linker histones with other cellular proteins are also discussed.
GRASPs in Golgi Structure and Function
Directory of Open Access Journals (Sweden)
Xiaoyan eZhang
2016-01-01
Full Text Available The Golgi apparatus is a central intracellular membrane organelle for trafficking and modification of proteins and lipids. Its basic structure is a stack of tightly aligned flat cisternae. In mammalian cells, dozens of stacks are concentrated in the pericentriolar region and laterally connected to form a ribbon. Despite extensive research in the last decades, how this unique structure is formed and why its formation is important for proper Golgi functioning remain largely unknown. The Golgi ReAssembly Stacking Proteins, GRASP65 and GRASP55, are so far the only proteins shown to function in Golgi stacking. They are peripheral membrane proteins on the cytoplasmic face of the Golgi cisternae that form trans-oligomers through their N-terminal GRASP domain, and thereby function as the glue to stick adjacent cisternae together into a stack and to link Golgi stacks into a ribbon. Depletion of GRASPs in cells disrupts the Golgi structure and results in accelerated protein trafficking and defective glycosylation. In this minireview we summarize our current knowledge on how GRASPs function in Golgi structure formation and discuss why Golgi structure formation is important for its function.
Viscosity of a nucleonic fluid
Mekjian, Aram Z
2012-01-01
The viscosity of nucleonic matter is studied both classically and in a quantum mechanical description. The collisions between particles are modeled as hard sphere scattering as a baseline for comparison and as scattering from an attractive square well potential. Properties associated with the unitary limit are developed which are shown to be approximately realized for a system of neutrons. The issue of near perfect fluid behavior of neutron matter is remarked on. Using some results from hard sphere molecular dynamics studies near perfect fluid behavior is discussed further.
Strange chiral nucleon form factors
Hemmert, T R; Meißner, Ulf G; Hemmert, Thomas R.; Kubis, Bastian; Meissner, Ulf-G.
1999-01-01
We investigate the strange electric and magnetic form factors of the nucleon in the framework of heavy baryon chiral perturbation theory to third order in the chiral expansion. All counterterms can be fixed from data. In particular, the two unknown singlet couplings can be deduced from the parity-violating electron scattering experiments performed by the SAMPLE and the HAPPEX collaborations. Within the given uncertainties, our analysis leads to a small and positive electric strangeness radius, $ = (0.05 \\pm 0.16) fm^2$. We also deduce the consequences for the upcoming MAMI A4 experiment.
Dispersion relations and the spin polarizabilities of the nucleon
Drechsel, D; Hanstein, O
1998-01-01
A forward dispersion calculation is implemented for the spin polarizabilities are related to the spin structure of the nucleon at low energies and are structure-constants of the Compton scattering amplitude at ${\\cal O}(\\omega^3)$. In the absence of a direct experimental measurement of these quantities, a dispersion calculation serves the purpose of constraining the model building, and of comparing with recent calculations in heavy baryon chiral perturbation theory.
Three-nucleon forces in exotic open-shell isotopes
Soma, V; Cipollone, A; Duguet, T; Navratil, P
2013-01-01
Advances in the self-consistent Green's function approach to finite nuclei are discussed, including the implementation of three-nucleon forces and the extension to the Gorkov formalism. We report results on binding energies in the nitrogen and fluorine isotopic chains, as well as spectral functions of 22O. The application to medium-mass open-shell systems is illustrated by separation energy spectra of two argon isotopes, which are compared to one-neutron removal experiments.
Nonperturbative contribution to the strange-antistrange asymmetry of the nucleon sea
Vega, Alfredo; Gutsche, Thomas; Lyubovitskij, Valery E
2015-01-01
We study the nonperturbative (intrinsic) contribution to the $s(x) - \\bar{s}(x)$ asymmetry of the nucleon sea. For this purpose we use different light-front wave functions inspired by the AdS/QCD formalism, together with a model of the nucleon in terms of meson-baryon fluctuations. The holographic wave functions for an arbitrary number of constituents, recently derived by us, give results quite close to known parametrizations that appear in the literature.
Roy-Steiner-equation analysis of pion-nucleon scattering
Hoferichter, Martin; Ruiz de Elvira, Jacobo; Kubis, Bastian; Meißner, Ulf-G.
2016-04-01
We review the structure of Roy-Steiner equations for pion-nucleon scattering, the solution for the partial waves of the t-channel process ππ → N ¯ N, as well as the high-accuracy extraction of the pion-nucleon S-wave scattering lengths from data on pionic hydrogen and deuterium. We then proceed to construct solutions for the lowest partial waves of the s-channel process πN → πN and demonstrate that accurate solutions can be found if the scattering lengths are imposed as constraints. Detailed error estimates of all input quantities in the solution procedure are performed and explicit parameterizations for the resulting low-energy phase shifts as well as results for subthreshold parameters and higher threshold parameters are presented. Furthermore, we discuss the extraction of the pion-nucleon σ-term via the Cheng-Dashen low-energy theorem, including the role of isospin-breaking corrections, to obtain a precision determination consistent with all constraints from analyticity, unitarity, crossing symmetry, and pionic-atom data. We perform the matching to chiral perturbation theory in the subthreshold region and detail the consequences for the chiral convergence of the threshold parameters and the nucleon mass.
Gupta, S; Musthafa, M M; Bhardwaj, H D; Prasadl, R
2000-01-01
This experiment has been done with a view to studying complete and incomplete fusion in heavy-ion-induced reactions. Excitation functions for several reactions induced by /sup 12/C/sup 5+/ ions on /sup 165/Ho at incident energies from 55 to 80 MeV have been measured using the activation technique. The analysis of the data has been done using the codes ALICE-91 and CASCADE. The parameter F/sub theta /, the ratio of actual moment of inertia to the rigid-body value, has been found to play an important role in the calculations done by the code CASCADE. Significant contributions from both the complete and the incomplete fusion channels have been observed. Further, in the case of the reaction (C, p3n) considerable contribution from the decay of higher charge isobar precursor has been observed. (23 refs).
Deep Inelastic Structure Functions at small x
Ermolaev, B I; Troyan, S I
2006-01-01
Explicit expressions for the non-singlet and singlet structure functions g_1 in the small-x region are obtained. They include the total resummation of the double- and single- logarithms of x and account for the running QCD coupling effects. Both the non-singlet and singlet structure functions are Regge behavied asymptotically, with the intercepts predicted in agreement with experiments. A detailed comparison with the DGLAP evolution equations for different values of x and Q^2 is performed. Finally, the role played by singular terms in DGLAP fits is discussed and explicitly shown to mimic the resummation of leading logarithms at small x.
Nucleon-nucleon interaction with one-pion exchange and instanton-induced interactions
Vanamali, C. S.; Kumar, K. B. Vijaya
2016-11-01
Singlet (S10) and triplet (S31) nucleon-nucleon potentials are obtained in the framework of the SU(2) nonrelativistic quark model using the resonating-group method in the Born-Oppenheimer approximation. The full Hamiltonian used in the investigation includes the kinetic energy, two-body confinement potential, one-gluon-exchange potential (OGEP), one-pion exchange potential (OPEP), and instanton induced interaction (III), which includes the effect of quark exchange between the nucleons. The contribution of the OGEP, III, and OPEP to the nucleon-nucleon adiabatic potential is discussed.
Structural and functional insights into Mimivirus ORFans
Directory of Open Access Journals (Sweden)
Fischer Daniel
2007-05-01
Full Text Available Abstract Background Mimivirus isolated from A. polyphaga is the largest virus discovered so far. It is unique among all the viruses in having genes related to translation, DNA repair and replication which bear close homology to eukaryotic genes. Nevertheless, only a small fraction of the proteins (33% encoded in this genome has been assigned a function. Furthermore, a large fraction of the unassigned protein sequences bear no sequence similarity to proteins from other genomes. These sequences are referred to as ORFans. Because of their lack of sequence similarity to other proteins, they can not be assigned putative functions using standard sequence comparison methods. As part of our genome-wide computational efforts aimed at characterizing Mimivirus ORFans, we have applied fold-recognition methods to predict the structure of these ORFans and further functions were derived based on conservation of functionally important residues in sequence-template alignments. Results Using fold recognition, we have identified highly confident computational 3D structural assignments for 21 Mimivirus ORFans. In addition, highly confident functional predictions for 6 of these ORFans were derived by analyzing the conservation of functional motifs between the predicted structures and proteins of known function. This analysis allowed us to classify these 6 previously unannotated ORFans into their specific protein families: carboxylesterase/thioesterase, metal-dependent deacetylase, P-loop kinases, 3-methyladenine DNA glycosylase, BTB domain and eukaryotic translation initiation factor eIF4E. Conclusion Using stringent fold recognition criteria we have assigned three-dimensional structures for 21 of the ORFans encoded in the Mimivirus genome. Further, based on the 3D models and an analysis of the conservation of functionally important residues and motifs, we were able to derive functional attributes for 6 of the ORFans. Our computational identification of important
Nucleon-XcJ Dissociation Cross Sections
Institute of Scientific and Technical Information of China (English)
冯又层; 许晓明; 周代翠
2002-01-01
Nucleon-XcJ dissociation cross sections are calculated in a constituent interexchange model in which quark-quark potential is derived from the Buchmüller-Tye quark-anti-quark potential. These new cross sections for dominant reaction channels depend on the centre-of-mass energy of the nucleon and the charmonium.
Charge-symmetry-breaking nucleon form factors
Kubis, Bastian
2009-01-01
A quantitative understanding of charge-symmetry breaking is an increasingly important ingredient for the extraction of the nucleon's strange vector form factors. We review the theoretical understanding of the charge-symmetry-breaking form factors, both for single nucleons and for Helium-4.
Unraveling the physical meaning of the Jaffe-Manohar decomposition of the nucleon spin
Wakamatsu, M.
2016-09-01
A general consensus now is that there are two physically inequivalent complete decompositions of the nucleon spin, i.e. the decomposition of the canonical type and that of mechanical type. The well-known Jaffe-Manohar decomposition is of the former type. Unfortunately, there is a wide-spread misbelief that this decomposition matches the partonic picture, which states that motion of quarks in the nucleon is approximately free. In the present monograph, we reveal that this understanding is not necessarily correct and that the Jaffe-Manohar decomposition is not such a decomposition, which natively reflects the intrinsic (or static) orbital angular momentum structure of the nucleon.
Nucleon shape and electromagnetic form factors in the chiral constituent quark model
Dahiya, Harleen
2010-01-01
The electromagnetic form factors are the most fundamental quantities to describe the internal structure of the nucleon and the shape of a spatially extended particle is determined by its intrinsic quadrupole moment which can be related to the charge radii. We have calculated the electromagnetic form factors, nucleon charge radii and the intrinsic quadrupole moment of the nucleon in the framework of chiral constituent quark model. The results obtained are comparable to the latest experimental studies and also show improvement over some theoretical interpretations.
Unravelling the physical meaning of the Jaffe-Manohar decomposition of the nucleon spin
Wakamatsu, Masashi
2016-01-01
A general consensus now is that there are two physically inequivalent complete decompositions of the nucleon spin, i.e. the decomposition of the canonical type and that of mechanical type. The well-known Jaffe-Manohar decomposition is of the former type. Unfortunately, there is a wide-spread misbelief that this decomposition matches the partonic picture, which states that motion of quarks in the nucleon is approximately free. In the present monograph, we reveal that this understanding is not necessarily correct and that the Jaffe-Manohar decomposition is not such a decomposition, which natively reflects the intrinsic (or static) orbital angular momentum structure of the nucleon.
Round table: Nucleon tomography. What can we do better today than Rutherford 100 years ago?
Stefanis, N. G.; Alexandrou, Constantia; Horn, Tanja; Moutarde, Hervé; Scimemi, Ignazio
2017-03-01
A survey is presented on the current status of 3D nucleon tomography. Several research frontiers are addressed that dominate modern physics from theory to current and future experiments. We have now a much more detailed spatial image of the nucleon thanks to various theoretical concepts and methods to describe its charge distribution and spin decomposition which are highlighted here. The progress of lattice computations of these quantities is reported and the prospects of what we can come to expect in the near future are discussed. Multi-dimensional maps of the nucleon's partonic structure appear now within reach of forthcoming experiments.
The structure of bivariate rational hypergeometric functions
Cattani, Eduardo; Villegas, Fernando Rodriguez
2009-01-01
We describe the structure of all codimension-two lattice configurations $A$ which admit a stable rational $A$-hypergeometric function, that is a rational function $F$ all whose partial derivatives are non zero, and which is a solution of the $A$-hypergeometric system of partial differential equations defined by Gel'fand, Kapranov and Zelevinsky. We show, moreover, that all stable rational $A$-hypergeometric functions may be described by toric residues and apply our results to study the rationality of bivariate series whose coefficients are quotients of factorials of linear forms.
Progress on nuclear modifications of structure functions
Directory of Open Access Journals (Sweden)
Kumano S.
2016-01-01
Full Text Available We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrinooscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function b1 is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact suggests that a new hadronic phenomenon should exist in the tensor-polarized deuteron at high energies, and it will be experimentally investigated at JLab from the end of 2010’s.
Structural Functionalism as a Heuristic Device.
Chilcott, John H.
1998-01-01
Argues that structural functionalism as a method for conducting fieldwork and as a format for the analysis of ethnographic data remains a powerful model, one that is easily understood by professional educators. As a heuristic device, functionalist theory can help in the solution of a problem that is otherwise incapable of theoretical…
[Structure and functions of glutathione transferases].
Fedets, O M
2014-01-01
Data about classification, nomenclature, structure, substrate specificity and role of many glutathione transferase's isoenzymes in cell functions have been summarised. The enzyme has been discovered more than 50 years ago. This family of proteins is updated continuously. It has very different composition and will have demand for system analysis for many years.
Polynomial Structure of Topological String Partition Functions
Zhou, Jie
2015-01-01
We review the polynomial structure of the topological string partition functions as solutions to the holomorphic anomaly equations. We also explain the connection between the ring of propagators defined from special K\\"ahler geometry and the ring of almost-holomorphic modular forms defined on modular curves.
Generalized functions, convergence structures, and their applications
Pap, Endre; Pilipović, Stevan; Vladimirov, Vasilij; International Conference "Generalized functions, convergence structures and their applications" (GFCA-87)
1988-01-01
This Proceedings consists of a collection of papers presented at the International Conference "Generalized functions, convergence structures and their applications" held from June 23-27, 1987 in Dubrovnik, Yugoslavia (GFCA-87): 71 participants from 21 countr~es from allover the world took part in the Conference. Proceedings reflects the work of the Conference. Plenary lectures of J. Burzyk, J. F. Colombeau, W. Gahler, H. Keiter, H. Komatsu, B. Stankovic, H. G. Tillman, V. S. Vladimirov provide an up-to-date account of the cur rent state of the subject. All these lectures, except H. G. Tillman's, are published in this volume. The published communications give the contemporary problems and achievements in the theory of generalized functions, in the theory of convergence structures and in their applications, specially in the theory of partial differential equations and in the mathematical physics. New approaches to the theory of generalized functions are presented, moti vated by concrete problems of applicat...
Protein tyrosine phosphatases: structure-function relationships.
Tabernero, Lydia; Aricescu, A Radu; Jones, E Yvonne; Szedlacsek, Stefan E
2008-03-01
Structural analysis of protein tyrosine phosphatases (PTPs) has expanded considerably in the last several years, producing more than 200 structures in this class of enzymes (from 35 different proteins and their complexes with ligands). The small-medium size of the catalytic domain of approximately 280 residues plus a very compact fold makes it amenable to cloning and overexpression in bacterial systems thus facilitating crystallographic analysis. The low molecular weight PTPs being even smaller, approximately 150 residues, are also perfect targets for NMR analysis. The availability of different structures and complexes of PTPs with substrates and inhibitors has provided a wealth of information with profound effects in the way we understand their biological functions. Developments in mammalian expression technology recently led to the first crystal structure of a receptor-like PTP extracellular region. Altogether, the PTP structural work significantly advanced our knowledge regarding the architecture, regulation and substrate specificity of these enzymes. In this review, we compile the most prominent structural traits that characterize PTPs and their complexes with ligands. We discuss how the data can be used to design further functional experiments and as a basis for drug design given that many PTPs are now considered strategic therapeutic targets for human diseases such as diabetes and cancer.
Charmonium-Nucleon Interaction from Quenched Lattice QCD with Relativistic Heavy Quark Action
Kawanai, Taichi; Sasaki, Shoichi; Hatsuda, Tetsuo
2009-10-01
Low energy charmonium-nucleon interaction is of particular interest in this talk. A heavy quarkonium state like the charmonium does not share the same quark flavor with the nucleon so that cc-nucleon interaction might be described by the gluonic van der Waals interaction, which is weak but attractive. Therefore, the information of the strength of cc-nucleon interaction is vital for considering the possibility of the formation of charmonium bound to nuclei. We will present the preliminary results for the scattering length and the interaction range of charmonium-nucleon s-wave scattering from quenched lattice QCD. These low-energy quantities can provide useful constraints on the phenomenological cc-nucleon potential, which is required for precise prediction of the binding energy of nuclear-bound charmonium in exact few body calculations. Our simulations are performed at a lattice cutoff of 1/a=2.0 GeV with the nonperturbatively O(a) improved Wilson action for the light quark and a relativistic heavy quark action for the charm quark. A new attempt of calculating the cc-nucleon potential through the Bethe-Salpeter wave function will be also discussed.
Influence of nucleonic motion in Relativistic Fermi Gas inclusive responses
Alvarez-Ruso, L; Donnelly, T W; Molinari, A
2001-01-01
Impulsive hadronic descriptions of electroweak processes in nuclei involve two distinctly different elements: one stems from the nuclear many-body physics --- the medium --- which is rather similar for the various inclusive response functions, and the other embodies the responses of the hadrons themselves to the electroweak probe and varies with the channel selected. In this letter we investigate within the context of the relativistic Fermi gas in both the quasi-elastic and $N\\to\\Delta$ regimes the interplay between these two elements. Specifically, we focus on expansions in the one small parameter in the problem, namely, the momentum of a nucleon in the initial wave function compared with the hadronic scale, the nucleon mass. Both parity-conserving and -violating inclusive responses are studied and the interplay between longitudinal ($L$) and transverse ($T$ and $T'$) contributions is highlighted.
Roy-Steiner equations for pion-nucleon scattering
Ditsche, C; Kubis, B; Meißner, U -G
2012-01-01
Starting from hyperbolic dispersion relations, we derive a closed system of Roy-Steiner equations for pion-nucleon scattering that respects analyticity, unitarity, and crossing symmetry. We work out analytically all kernel functions and unitarity relations required for the lowest partial waves. In order to suppress the dependence on the high-energy regime we also consider once- and twice-subtracted versions of the equations, where we identify the subtraction constants with subthreshold parameters. Assuming Mandelstam analyticity we determine the maximal range of validity of these equations. As a first step towards the solution of the full system we cast the equations for the $\\pi\\pi\\to\\bar NN$ partial waves into the form of a Muskhelishvili-Omn\\`es problem with finite matching point, which we solve numerically in the single-channel approximation. We investigate in detail the role of individual contributions to our solutions and discuss some consequences for the spectral functions of the nucleon electromagneti...
Backward pion-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Huang, F. [Univ. of Georgia, Athens, GA (United States); Sibirtsev, Alex [Helmholtz-Institut furr Strahlen- und Kernphysik (Theorie) und Bethe Center for Theoretical Physics, Universitat Bonn, D-53115 Bonn, Germany; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Haidenbauer, Johann [Forschungszentrum Julich (Germany); Meissner, Ulf-G. [Helmholtz-Institut fur Strahlen- und Kernphysik (Theorie) und Bethe Center for Theoretical Physics, Universitat Bonn, Bonn, Germany; Forschungszentrum Julich (Germany)
2010-02-01
A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the $N_\\alpha$, $N_\\gamma$, $\\Delta_\\delta$ and $\\Delta_\\beta$ trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable $u$, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a $G_{39}$ resonance with a mass of 2.83 GeV as member of the $\\Delta_{\\beta}$ trajectory from the corresponding Chew-Frautschi plot.
Pion production off the nucleon
Alam, M Rafi; Chauhan, Shikha; Singh, S K
2016-01-01
We have studied charged current neutrino/antineutrino induced weak pion production from nucleon. For the present study, contributions from $\\Delta(1232)$-resonant term, non-resonant background terms as well as contribution from higher resonances viz. $P_{11}$(1440), $D_{13}$(1520), $S_{11}$(1535), $S_{11}$(1650) and $P_{13}$(1720) are taken. To write the hadronic current for the non-resonant background terms, a microscopic approach based on SU(2) non-linear sigma model has been used. The vector form factors for the resonances are obtained from the helicity amplitudes provided by MAID. Axial coupling in the case of $\\Delta(1232)$ resonance is obtained by fitting the ANL and BNL $\
Nucleon Resonances in Kaon Photoproduction
Bennhold, C; Waluyo, A; Haberzettl, H; Penner, G; Feuster, T; Mosel, U
1999-01-01
Nucleon resonances are investigated through the electromagnetic production of K-mesons. We study the kaon photoproduction process at tree-level and compare to a recently developed unitary K-matrix approach. Employing hadronic form factors along with the proper gauge prescription yields suppression of the Born terms and leads a resonance dominated process for both K-Lambda and K-Sigma photoproduction. Using new SAPHIR data we find the K+-Lambda photoproduction to be dominated by the S11(1650) at threshold, with additional contributions from the P11(1710) and P13(1720) states. The K-Sigma channel couples to a cluster of Delta resonances around W = 1900 MeV. We briefly discuss some tantalizing evidence for a missing D13 resonance around 1900 MeV with a strong branching ratio into KLambda channel.
Braun, V M; Gläßle, B; Göckeler, M; Schäfer, A; Schiel, R W; Söldner, W; Sternbeck, A; Wein, P
2014-01-01
We present the results of a lattice study of light-cone distribution amplitudes (DAs) of the nucleon and negative parity nucleon resonances using two flavors of dynamical (clover) fermions on lattices of different volumes and pion masses down to m_pi = 150 MeV. We find that the three valence quarks in the proton share their momentum in the proportion 37% : 31% : 31%, where the larger fraction corresponds to the u-quark that carries proton helicity, and determine the value of the wave function at the origin in position space, which turns out to be small compared to the existing estimates based on QCD sum rules. Higher-order moments are constrained by our data and are all compatible with zero within our uncertainties. We also calculate the normalization constants of the higher-twist DAs that are related to the distribution of quark angular momentum. Furthermore, we use the variational method and customized parity projection operators to study the states with negative parity. In this way we are able to separate ...
Electromagnetic form factors in a collective model of the nucleon
Bijker, R; Leviatan, A
1995-01-01
We study the electromagnetic form factors of the nucleon in a collective model of baryons. Using the algebraic approach to hadron structure, we derive closed expressions for both elastic and transition form factors, and consequently for the helicity amplitudes that can be measured in electro- and photoproduction. Effects of spin-flavor symmetry breaking and of swelling of hadrons with increasing excitation energy are considered.
Electromagnetic form factors in a collective model of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Bijker, R.; Iachello, F.; Leviatan, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510 (Mexico)]|[Distrito Federale (Mexico)]|[Center for Theoretical Physics, Sloane Laboratory, Yale University, New Haven, Connecticut 06520-8120 (United States)]|[Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)
1996-10-01
We study the electromagnetic form factors of the nucleon in a collective model of baryons. Using the algebraic approach to hadron structure, we derive closed expressions for both elastic and transition form factors, and consequently for the helicity amplitudes that can be measured in electro- and photoproduction. Effects of spin-flavor symmetry breaking and of swelling of hadrons with increasing excitation energy are considered. {copyright} {ital 1996 The American Physical Society.}
Longitudinal Structure Function FL from Charm Structure Function F2c
Institute of Scientific and Technical Information of China (English)
B.Rezaei; G.R.Boroun
2013-01-01
We predict the effect of the charm structure function on the longitudinal structure function at small x.In NLO analysis we find that the hard Pomeron behavior gives a good description of FL and Fkc (k =2,L) at small x values.We conclude that a direct relation between FL∝ F2c would provide useful information on how to measure longitudinal structure function at high Q2 values.Having checked that this model gives a good description of the data,when compared with other models.
Proteins with Novel Structure, Function and Dynamics
Pohorille, Andrew
2014-01-01
Recently, a small enzyme that ligates two RNA fragments with the rate of 10(exp 6) above background was evolved in vitro (Seelig and Szostak, Nature 448:828-831, 2007). This enzyme does not resemble any contemporary protein (Chao et al., Nature Chem. Biol. 9:81-83, 2013). It consists of a dynamic, catalytic loop, a small, rigid core containing two zinc ions coordinated by neighboring amino acids, and two highly flexible tails that might be unimportant for protein function. In contrast to other proteins, this enzyme does not contain ordered secondary structure elements, such as alpha-helix or beta-sheet. The loop is kept together by just two interactions of a charged residue and a histidine with a zinc ion, which they coordinate on the opposite side of the loop. Such structure appears to be very fragile. Surprisingly, computer simulations indicate otherwise. As the coordinating, charged residue is mutated to alanine, another, nearby charged residue takes its place, thus keeping the structure nearly intact. If this residue is also substituted by alanine a salt bridge involving two other, charged residues on the opposite sides of the loop keeps the loop in place. These adjustments are facilitated by high flexibility of the protein. Computational predictions have been confirmed experimentally, as both mutants retain full activity and overall structure. These results challenge our notions about what is required for protein activity and about the relationship between protein dynamics, stability and robustness. We hypothesize that small, highly dynamic proteins could be both active and fault tolerant in ways that many other proteins are not, i.e. they can adjust to retain their structure and activity even if subjected to mutations in structurally critical regions. This opens the doors for designing proteins with novel functions, structures and dynamics that have not been yet considered.
A measurement of the neutral current neutrino-nucleon elastic cross section at MiniBooNE
Energy Technology Data Exchange (ETDEWEB)
Cox, David Christopher [Indiana Univ., Bloomington, IN (United States)
2008-02-01
The neutral current neutrino-nucleon elastic interaction v N → v N is a fundamental process of the weak interaction ideally suited for characterizing the structure of the nucleon neutral weak current. This process comprises ~18% of neutrino events in the neutrino oscillation experiment, MiniBooNE, ranking it as the experiment's third largest process. Using ~10% of MiniBooNE's available neutrino data, a sample of these events were identified and analyzed to determine the differential cross section as a function of the momentum transfer of the interaction, Q^{2}. This is the first measurement of a differential cross section with MiniBooNE data. From this analysis, a value for the nucleon axial mass M_{A} was extracted to be 1.34 ± 0.25 GeV consistent with previous measurements. The integrated cross section for the Q^{2} range 0.189 → 1.13 GeV^{2} was calculated to be (8.8 ± 0.6(stat) ± 0.2(syst)) x 10^{-40} cm^{2}.
Phosphatidylinositol 4-kinases: Function, structure, and inhibition
Energy Technology Data Exchange (ETDEWEB)
Boura, Evzen, E-mail: boura@uochb.cas.cz; Nencka, Radim, E-mail: nencka@uochb.cas.cz
2015-10-01
The phosphatidylinositol 4-kinases (PI4Ks) synthesize phosphatidylinositol 4-phosphate (PI4P), a key member of the phosphoinositide family. PI4P defines the membranes of Golgi and trans-Golgi network (TGN) and regulates trafficking to and from the Golgi. Humans have two type II PI4Ks (α and β) and two type III enzymes (α and β). Recently, the crystal structures were solved for both type II and type III kinase revealing atomic details of their function. Importantly, the type III PI4Ks are hijacked by +RNA viruses to create so-called membranous web, an extensively phosphorylated and modified membrane system dedicated to their replication. Therefore, selective and potent inhibitors of PI4Ks have been developed as potential antiviral agents. Here we focus on the structure and function of PI4Ks and their potential in human medicine.
Multimodality imaging of structure and function
Energy Technology Data Exchange (ETDEWEB)
Townsend, D W [Departments of Medicine and Radiology, University of Tennessee Medical Center, 1924 Alcoa Highway, Knoxville, TN 37920 (United States)], E-mail: dtownsend@mc.utmck.edu
2008-02-21
Historically, medical devices to image either anatomical structure or functional processes have developed along somewhat independent paths. The recognition that combining images from different modalities can nevertheless offer significant diagnostic advantages gave rise to sophisticated software techniques to coregister structure and function. Recently, alternatives to retrospective software-based fusion have become available through instrumentation that combines two imaging modalities within a single device, an approach that has since been termed hardware fusion. As a result, following their recent introduction into the clinic, combined PET/CT and SPECT/CT devices are now playing an increasingly important role in the diagnosis and staging of human disease. Recently, although limited to the brain, the first clinical MR scanner with a PET insert, a technically-challenging design, has been undergoing evaluation. This review will follow the development of multimodality instrumentation for clinical use from conception to present-day technology and assess the status and future potential for such devices. (topical review)
Negative-parity nucleon excited state in nuclear matter
Ohtani, Keisuke; Oka, Makoto
2016-01-01
Spectral functions of the nucleon and its negative parity excited state in nuclear matter are studied using QCD sum rules and the maximum entropy method (MEM). It is found that in-medium modifications of the spectral functions are attributed mainly to density dependencies of the $\\langle \\bar{q}q \\rangle $ and $\\langle q^{\\dagger}q \\rangle $ condensates. The MEM reproduces the lowest-energy peaks of both the positive and negative parity nucleon states at finite density up to $\\rho \\sim \\rho_N$ (normal nuclear matter density). As the density grows, the residue of the nucleon ground state decreases gradually while the residue of the lowest negative parity excited state increases slightly. On the other hand, the positions of the peaks, which correspond to the total energies of these states, are almost density independent for both parity states. The density dependencies of the effective masses and vector self-energies are also extracted by assuming the mean-field green functions for the peak states. We find that,...
Relativistic Treatments of the Nucleon-Nucleon System
Beachey, David Joseph
The relativistically minimalist Breit equation is used to study the two-nucleon system. Generally, the equation is noncovariant and its realm of applicability is limited. It is not a field-theoretical equation but, at low energy, it was thought to be a promising candidate to explore the scheme of repulsive vector and attractive scalar interactions as the dominant ingredient of the two -nucleon interaction. In the ^1S_0 singlet case, the equation does indeed seem viable. Dynamically sound interactions and a reasonable fit of the scattering data arise. In a specific application, the discrepancy between the ^1S_0 isovector scattering lengths of the p-p and n -n interactions is explored. This novel charge -symmetry-breaking (CSB) mechanism enlarges the discrepancy between the two lengths, implying a still larger correction is required by other documented (CSB) mechanisms. An all-encompassing model of the ^3S _1-^3D_1 state is, on the other hand, not achieved. Models which best fit the experimental deuteron and elastic scattering data, are unphysical. The vector coupling is driven strongly negative and a dominant interference mechanism arises involving the entirely phenomenological short range OPEP. It was hoped that this parametrized short range OPEP would remain benign while the scalar/vector interference scheme took a lead role. Instead the constraint of avoiding Klein paradox difficulties defeats this picture and achieves the short-range repulsion in the N-N force by ramping up the phenomenological OPEP. It is finally argued that the Breit framework almost certainly does not lend itself to an adequate description of the N-N system. It does, however, point to novel relativistic elements which may ultimately resolve celebrated outstanding problems such as the a_ {t}-r_{m} discrepancy. The triplet scattering length a_ {t} and deuteron matter-radius r _{m} are tightly correlated and resistant to simultaneous fitting in conventional models. The p-wave amplitudes of the
Structure and function of mammalian cilia
DEFF Research Database (Denmark)
Satir, Peter; Christensen, Søren T
2008-01-01
In the past half century, beginning with electron microscopic studies of 9 + 2 motile and 9 + 0 primary cilia, novel insights have been obtained regarding the structure and function of mammalian cilia. All cilia can now be viewed as sensory cellular antennae that coordinate a large number...... of cellular signaling pathways, sometimes coupling the signaling to ciliary motility or alternatively to cell division and differentiation. This view has had unanticipated consequences for our understanding of developmental processes and human disease....
General Structures of Block Based Interpolational Function
Institute of Scientific and Technical Information of China (English)
ZOU LE; TANG SHUO; Ma Fu-ming
2012-01-01
We construct general structures of one and two variable interpolation function,without depending on the existence of divided difference or inverse differences,and we also discuss the block based osculatory interpolation in one variable case.Clearly,our method offers many flexible interpolation schemes for choices.Error terms for the interpolation are determined and numerical examples are given to show the effectiveness of the results.
Anisotropic nanomaterials: structure, growth, assembly, and functions
Panikkanvalappil R. Sajanlal; Theruvakkattil S. Sreeprasad; Samal, Akshaya K.; Thalappil Pradeep
2011-01-01
Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates...
Quark model for kaon nucleon scattering
Indian Academy of Sciences (India)
Ahmed Osman
2011-12-01
Kaon nucleon elastic scattering is studied using chiral (3) quark model including antiquarks. Parameters of the present model are essentially based on nucleon–nucleon and nucleon–hyperon interactions. The mass of the scalar meson is taken as 635 MeV. Using this model, the phase shifts of the and partial waves of the kaon nucleon elastic scattering are investigated for isospins 0 and 1. The results of the numerical calculations of different partial waves are in good agreement with experimental data.
On the strangeness content of the nucleon
Alarcon, J M; Camalich, J Martin; Oller, J A
2012-01-01
We revisit the classical relation between the strangeness content of the nucleon, the pion-nucleon sigma term and the $SU(3)_F$ breaking of the baryon masses in the context of covariant chiral perturbation theory. In particular, we consider the contributions of the decuplet resonances explicitly. We find that a value of the pion-nucleon sigma term of $\\sim$60 MeV is not at odds with, but favored by the fulfillment of the Zweig rule. We compare these results with earlier ones and discuss the convergence of the chiral series as well as the uncertainties of chiral approaches to the determination of the sigma terms.
Industrial entrepreneurial network: Structural and functional analysis
Medvedeva, M. A.; Davletbaev, R. H.; Berg, D. B.; Nazarova, J. J.; Parusheva, S. S.
2016-12-01
Structure and functioning of two model industrial entrepreneurial networks are investigated in the present paper. One of these networks is forming when implementing an integrated project and consists of eight agents, which interact with each other and external environment. The other one is obtained from the municipal economy and is based on the set of the 12 real business entities. Analysis of the networks is carried out on the basis of the matrix of mutual payments aggregated over the certain time period. The matrix is created by the methods of experimental economics. Social Network Analysis (SNA) methods and instruments were used in the present research. The set of basic structural characteristics was investigated: set of quantitative parameters such as density, diameter, clustering coefficient, different kinds of centrality, and etc. They were compared with the random Bernoulli graphs of the corresponding size and density. Discovered variations of random and entrepreneurial networks structure are explained by the peculiarities of agents functioning in production network. Separately, were identified the closed exchange circuits (cyclically closed contours of graph) forming an autopoietic (self-replicating) network pattern. The purpose of the functional analysis was to identify the contribution of the autopoietic network pattern in its gross product. It was found that the magnitude of this contribution is more than 20%. Such value allows using of the complementary currency in order to stimulate economic activity of network agents.
Structural and functional neuroimaging in intractable epilepsy
Directory of Open Access Journals (Sweden)
Chinchure Swati
2010-01-01
Full Text Available Medical management remains unsatisfactory in about a third of patients with epilepsy and some of them are candidates for resective epilepsy surgery. Structural and functional neuroimaging plays an important role in the identification of the precise cortical region responsible for seizures and is very crucial for a good surgical outcome. Furthermore, identification of eloquent cortical areas near the region to be resected is essential to avoid postoperative neurologic deficit. The magnetic resonance imaging (MRI protocol for epilepsy can be individually tailored depending on the seizure semiology and possibly electroencephalography. New MRI techniques demonstrate the structure of the brain in fine detail, help in understanding the underlying pathology, and demonstrate functional activity of the brain with high spatial and temporal resolution. Metabolic imaging techniques, such as positron emission tomography (PET and single photon emission tomography (SPECT visualize metabolic alterations of the brain in the ictal and interictal states. In MR-negative epilepsy patients, these techniques may have localizing value. The proper use and interpretation of the findings provided by these new technologies is crucial. In this review article, we discuss various conventional and advanced MRI techniques, interpretation of various findings, and the role of functional imaging modalities, such as functional MRI, PET, and SPECT in the localization of epileptogenic substrate as well as for understanding the pathophysiology, propagation, and neurochemical correlates of epilepsy.
11th Workshop on The Physics of Excited Nucleons
Hammer, Hans-Werner; Thoma, Ulrike; Schmieden, Hartmut; NSTAR 2007
2008-01-01
The excitation spectrum of the nucleon promises to offer important insights into the non-perturbative regime of QCD. Dedicated experimental programs at various laboratories exist to perform accurate measurements of meson photo- and electroproduction off the nucleon, studying its excitation. The NStar workshops are a well-established series of meetings that bring together experimenters and theoreticians working on baryon resonances and related areas to discuss New results on pseudoscalar and vector meson production; Partial wave analysis and resonance parameters; Baryon resonance structure and quark models; Dynamical models and coupled channel analysis; Baryon resonances in lattice QCD; Chiral symmetry and baryon resonances; Laboratory reports and future projects. The refereed and edited proceedings constitute an indispensable archival record of the progress in the field.
Multi-Nucleon Exchange in Quasi-Fission Reactions
Ayik, S; Yilmaz, O
2015-01-01
Nucleon exchange mechanism is investigated in the central collisions of ${}^{40}$Ca + ${}^{238}$U and ${}^{48}$Ca + ${}^{238}$U systems near the quasi-fission regime in the framework of the Stochastic Mean-Field (SMF) approach. Sufficiently below the fusion barrier, di-nuclear structure in the collisions is maintained to a large extend. Consequently, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Diffusion coefficients for proton and neutron exchange are determined from the microscopic basis of the SMF approach in the semi-classical framework. Calculations show that after a fast charge equilibration the system drifts toward symmetry over a very long interaction time. Large dispersions of proton and neutron distributions of the produced fragments indicate that diffusion mechanism may help to populate heavy trans-uranium elements near the quasi-fission regime in these collisions.
Transverse Force on Transversely Polarized Quarks in Longitudinally Polarized Nucleons
Abdallah, Manal
2016-01-01
We study the semi-classical interpretation of the $x^3$ and $x^4$ moments of twist-3 parton distribution functions (PDFs). While no semi-classical interpretation for the higher moments of $g_T(x)$ and $e(x)$ was find, the $x^3$ moment of the chirally odd spin-dependent twist-3 PDF $h_L^3(x)$ can be related to the longitudinal gradient of the transverse force on transversely polarized quarks in longitudinally polarized nucleons in a DIS experiment. We discuss how this result relates to the torque acting on a quark in the same experiment. This has further implications for comparisons between tha Jaffe-Manohar and the Ji decompositions of the nucleon spin.
Nucleon matrix elements using the variational method in lattice QCD
Dragos, J.; Horsley, R.; Kamleh, W.; Leinweber, D. B.; Nakamura, Y.; Rakow, P. E. L.; Schierholz, G.; Young, R. D.; Zanotti, J. M.
2016-10-01
The extraction of hadron matrix elements in lattice QCD using the standard two- and three-point correlator functions demands careful attention to systematic uncertainties. One of the most commonly studied sources of systematic error is contamination from excited states. We apply the variational method to calculate the axial vector current gA, the scalar current gS, the scalar current gT and the quark momentum fraction ⟨x ⟩ of the nucleon and we compare the results to the more commonly used summation and two-exponential fit methods. The results demonstrate that the variational approach offers a more efficient and robust method for the determination of nucleon matrix elements.
Quantum Monte Carlo Calculations of Nucleon-Nucleus Scattering
Wiringa, R. B.; Nollett, Kenneth M.; Pieper, Steven C.; Brida, I.
2009-10-01
We report recent quantum Monte Carlo (variational and Green's function) calculations of elastic nucleon-nucleus scattering. We are adding the cases of proton-^4He, neutron-^3H and proton-^3He scattering to a previous GFMC study of neutron-^4He scattering [1]. To do this requires generalizing our methods to include long-range Coulomb forces and to treat coupled channels. The two four-body cases can be compared to other accurate four-body calculational methods such as the AGS equations and hyperspherical harmonic expansions. We will present results for the Argonne v18 interaction alone and with Urbana and Illinois three-nucleon potentials. [4pt] [1] K.M. Nollett, S. C. Pieper, R.B. Wiringa, J. Carlson, and G.M. Hale, Phys. Rev. Lett. 99, 022502 (2007)
Energy Technology Data Exchange (ETDEWEB)
El Yakoubi, M.A
2007-03-15
The PVA4 experiment (Parity Violating in hall A4 in Mainz) aims at assessing the contribution of the strange quark to the charge and current distributions in the nucleon. In order to determine these distributions, measurements of the elastic scattering of longitudinal polarized electrons on a hydrogen target have been performed. 2 types of interaction are involved in this experiment: the electromagnetic interaction (virtual photon exchange) that dominates, and the weak interaction (neutral Z{sup 0} boson exchange). The non-conservation of the parity in the weak interaction induces an asymmetry in the counting rate according to the helicity of the electron beam. The difficulty of this experiment is that it requires the control of the systematic errors and the recording of high statistics due to the low asymmetry (about 10{sup -5} and 10{sup -6} according to the transferred momentum). This document presents the first Rosenbluth separation specific to the PVA4 at Q = 0.23 GeV/c{sup 2}. A formalism related to the violation of parity to separate the strange form factors is developed. The PVA4 experimental setup dedicated to the experiment is given, as well as the Monte-Carlo technique used to extract the strange quark contribution is detailed. The data analysis at forwards and backwards angles has enabled us to determine the following asymmetry values of parity violation: (-5.44 {+-} 0.54 (stat) {+-} 0.26 (sys)) ppm forwards and (-17.1 {+-} 1.4 (stat)) ppm backwards. The combining of these asymmetry values at Q = 0.23 GeV/c{sup 2} has led to the determination of the strange form factors G{sub E}{sup s} and G{sub M}{sup s}: G{sub E}{sup s} = (0.047 {+-} 0.041) and G{sub M}{sup s} = (-0.052 {+-} 0.164). It is also shown that while the strange quark electric component is compatible with a null value, a non-zero contribution of the magnetic part is possible.
Phenylalanine hydroxylase: function, structure, and regulation.
Flydal, Marte I; Martinez, Aurora
2013-04-01
Mammalian phenylalanine hydroxylase (PAH) catalyzes the rate-limiting step in the phenylalanine catabolism, consuming about 75% of the phenylalanine input from the diet and protein catabolism under physiological conditions. In humans, mutations in the PAH gene lead to phenylketonuria (PKU), and most mutations are mainly associated with PAH misfolding and instability. The established treatment for PKU is a phenylalanine-restricted diet and, recently, supplementation with preparations of the natural tetrahydrobiopterin cofactor also shows effectiveness for some patients. Since 1997 there has been a significant increase in the understanding of the structure, catalytic mechanism, and regulation of PAH by its substrate and cofactor, in addition to improved correlations between genotype and phenotype in PKU. Importantly, there has also been an increased number of studies on the structure and function of PAH from bacteria and lower eukaryote organisms, revealing an additional anabolic role of the enzyme in the synthesis of melanin-like pigments. In this review, we discuss these recent studies, which contribute to define the evolutionary adaptation of the PAH structure and function leading to sophisticated regulation for effective catabolic processing of phenylalanine in mammalian organisms.
The structure and function of presynaptic endosomes
Energy Technology Data Exchange (ETDEWEB)
Jähne, Sebastian, E-mail: sebastian.jaehne1@stud.uni-goettingen.de [Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Humboldtallee 23, 37073 Göttingen (Germany); International Max Planck Research School for Neurosciences, 37077 Göttingen (Germany); Rizzoli, Silvio O. [Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Humboldtallee 23, 37073 Göttingen (Germany); Helm, Martin S., E-mail: martin.helm@med.uni-goettingen.de [Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Humboldtallee 23, 37073 Göttingen (Germany); International Max Planck Research School for Molecular Biology, 37077 Göttingen (Germany)
2015-07-15
The function of endosomes and of endosome-like structures in the presynaptic compartment is still controversial. This is in part due to the absence of a consensus on definitions and markers for these compartments. Synaptic endosomes are sometimes seen as stable organelles, permanently present in the synapse. Alternatively, they are seen as short-lived intermediates in synaptic vesicle recycling, arising from the endocytosis of large vesicles from the plasma membrane, or from homotypic fusion of small vesicles. In addition, the potential function of the endosome is largely unknown in the synapse. Some groups have proposed that the endosome is involved in the sorting of synaptic vesicle proteins, albeit others have produced data that deny this possibility. In this review, we present the existing evidence for synaptic endosomes, we discuss their potential functions, and we highlight frequent technical pitfalls in the analysis of this elusive compartment. We also sketch a roadmap to definitely determine the role of synaptic endosomes for the synaptic vesicle cycle. Finally, we propose a common definition of synaptic endosome-like structures.
STRUCTURE AND GRAMMATICAL FUNCTION OF LEO LANGUAGE
Directory of Open Access Journals (Sweden)
I Ketut Yudha
2015-01-01
Full Text Available Lio language is a language spoken in Central Flores. Having limited morphological process in general and affixation process involving verbs (head marking and nouns (dependent marking in particular, it is classified into an isolating language. The studies exploring the languages spoken in the eastern part of Indonesia using Lexical Functional Grammar and the theory of typology are highly limited. In addition, Lio language is merely an isolating one and does not have cross referencing. It is this which inspired the writer to conduct research in syntax. This study aims at investigating the canonic structure, the types of verbs used as predicates, the grammatical function, the alternate of clausal structure, the mapping and the pivotance in Lio language. The results of analysis show that the clauses in Lio language can be divided into basic clauses with verbal and nonverbal predicates. The predicates of the verbal clauses are classified into simple, serial, and causative. The serial verbal constructions are distinguished based on the semantic features of the verbal components forming the serial verbal constructions. These types can be observed from the nature of the relationships among the components forming the serial verbal constructions. A serial verbal construction is made up of more than one verbs and behaves as a simple predicate. There is no dependence marker among the components forming the serial verb. The causative structure also forms monoclause and biclause. The functional mapping uses the features [+/-r] and [+/-o], the argument uses the features [-r] and [-o] which are mapped to SUBJ, [-r] and [+o] are mapped to OBJ, [+r] and [+o] are mapped to OBJ2 or OBJ? and [+r] and [-o] are mapped to OBL (Oblique. Lio language has GF SUBJ and OBJ as the nuclear GF (nuclear grammatical function, and OBL, COMP, and ADJ as the nonnuclear grammatical functions. The SUBJ appears before the verb (preverbal position and the OBJ appears after the
Nucleon distribution amplitudes from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics; Kaltenbrunner, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (DE). John von Neumann-Inst. fuer Computing NIC] (and others)
2008-04-15
We calculate low moments of the leading-twist and next-to-leading twist nucleon distribution amplitudes on the lattice using two flavors of clover fermions. The results are presented in the MS scheme at a scale of 2 GeV and can be immediately applied in phenomenological studies. We find that the deviation of the leading-twist nucleon distribution amplitude from its asymptotic form is less pronounced than sometimes claimed in the literature. (orig.)
Measurement of the Breakup Cross Sections in 6He+9Be Reaction at 25 MeV/Nucleon
Institute of Scientific and Technical Information of China (English)
WANG Jia; HU Qing-Yuan; WU Cui-E; A. Ozawa; Y. Yamaguchi; R. Kanungo; D. Fang; I. Tanihata; YE Yan-Lin; JIANG Dong-Xing; ZHANG Gao-Long; PANG Dan-Yang; LI Zhi-Huan; ZHENG Tao; LI Xiang-Qing; WANG Quan-Jin
2005-01-01
@@ The breakup reaction cross sections were measured for the reaction of 6He at 25 MeV/nucleon from 9Be target with intensity of 105 pps. By fitting the energy spectra of breakup α particles with Gaussian functions, the angular distribution of differential cross sections in the laboratory system has been extracted and compared with the Serber model calculations. The good agreement between the calculation and the experimental data favours a dominant configuration of the 4He core plus valence neutrons for the structure of 6He.
Two-pion exchange nucleon-nucleon potential: relativistic chiral expansion
Higa, R
2003-01-01
We present a relativistic procedure for the chiral expansion of the two-pion exchange component of the $NN$ potential, which emphasizes the role of intermediate $\\pi N$ subamplitudes. The relationship between power counting in $\\pi N$ and $NN$ processes is discussed and results are expressed directly in terms of observable subthreshold coefficients. Interactions are determined by one and two-loop diagrams, involving pions, nucleons and other degrees of freedom, frozen into empirical subthreshold coefficients. The full evaluation of these diagrams produces amplitudes containing many different loop integrals. Their simplification by means of relations among these integrals leads to a set of intermediate results. Subsequent truncation to $O(q^4)$ yields the relativistic potential, which depends on five loop integrals, representing bubble, triangle, crossed box and box diagrams. The bubble and triangle integrals are the same as in $\\pi N$ scattering and we have shown that they also determine the chiral structures...
Tropomyosin structure and function new insights.
Muthuchamy, M; Rethinasamy, P; Wieczorek, D F
1997-05-01
Cardiac muscle contraction is dependent upon a cooperative interaction between thick and thin filament sarcomeric proteins. Tropomyosin (TM), an essential thin filament protein, interacts with actin and the troponin complex to regulate contractile activity. During muscle contraction, an increase of calcium (Ca(2+)) in the myofilament space promotes binding of Ca(2+) to troponin C, which alters the conformational state of TM and facilitates acto-myosin interactions. By coupling classic genetic approaches with recent developments in transgenic animal model systems, new insights have been provided on the functional role of TM isoforms in both normal and disease states. The focus of this article is to review the current state of knowledge on TM structure and function, with a particular emphasis on myocardial expression in transgenic mouse model systems. (Trends Cardiovasc Med 1997;7:124-128). © 1997, Elsevier Science Inc.
MRI in Optic Neuritis: Structure, Function, Interactions
DEFF Research Database (Denmark)
Fuglø, Dan
2011-01-01
resonance imaging (MRI), and the visual evoked potential (VEP) continues to show a delayed P100 indicating persistent demyelination. The explanation for this apparent discrepancy between structure and function could be due to either a redundancy in the visual pathways so that some degree of signal loss...... are low. Functional MRI (fMRI) is a non-invasive technique that can measure brain activity with a high spatial resolution. Recently, technical and methodological advancements have made it feasible to record VEPs and fMRI simultaneously and the relationship between averaged VEPs and averaged fMRI signals...... have been described. Still, to take full advantage of simultaneously recorded VEP-fMRI one would ideally want to track single-trial changes in the VEP and use this information in the fMRI analysis. In order to do this we examined 10 healthy volunteers with simultaneous VEP-fMRI. Different measures...
Soft matter nanotechnology from structure to function
Chen, Xiaodong
2015-01-01
Using the well-honed tools of nanotechnology, this book presents breakthrough results in soft matter research, benefitting from the synergies between the chemistry, physics, biology, materials science, and engineering communities. The team of international authors delves beyond mere structure-making and places the emphasis firmly on imparting functionality to soft nanomaterials with a focus on devices and applications. Alongside reviewing the current level of knowledge, they also put forward novel ideas to foster research and development in such expanding fields as nanobiotechnology and nanom
Nucleon Structure Studies with Electromagnetic Probes
Energy Technology Data Exchange (ETDEWEB)
Vineyard, Michael F.
2011-03-31
Summarized in this report is the progress achieved during the period from March 1, 2008 to June 14, 2009 under contract number DE-FG02-03ER41252. This is the final technical report under this contract. The experimental work described here is part of the electromagnetic nuclear physics program of the CEBAF Large Acceptance Spectrometer (CLAS) Collaboration at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) that published 17 journal articles during the period of this report. One of these journal articles reported on the results of precise measurements of the neutron magnetic form factor. I was a spokesperson on this experiment and the publication of these results is the culmination of years of effort by a small subset of the CLAS Collaboration. As usual, undergraduate students were involved in all aspects of this work. Three Union College students participated in this program during the window of this report and one presented a paper on his work at the 2009 National Conference on Undergraduate Research (NCUR22). In this report, I discuss recent progress on the measurements of the neutron magnetic form factor and describe my service work for the CLAS Collaboration.
Structure, expression and functions of MTA genes.
Kumar, Rakesh; Wang, Rui-An
2016-05-15
Metastatic associated proteins (MTA) are integrators of upstream regulatory signals with the ability to act as master coregulators for modifying gene transcriptional activity. The MTA family includes three genes and multiple alternatively spliced variants. The MTA proteins neither have their own enzymatic activity nor have been shown to directly interact with DNA. However, MTA proteins interact with a variety of chromatin remodeling factors and complexes with enzymatic activities for modulating the plasticity of nucleosomes, leading to the repression or derepression of target genes or other extra-nuclear and nucleosome remodeling and histone deacetylase (NuRD)-complex independent activities. The functions of MTA family members are driven by the steady state levels and subcellular localization of MTA proteins, the dynamic nature of modifying signals and enzymes, the structural features and post-translational modification of protein domains, interactions with binding proteins, and the nature of the engaged and resulting features of nucleosomes in the proximity of target genes. In general, MTA1 and MTA2 are the most upregulated genes in human cancer and correlate well with aggressive phenotypes, therapeutic resistance, poor prognosis and ultimately, unfavorable survival of cancer patients. Here we will discuss the structure, expression and functions of the MTA family of genes in the context of cancer cells.
Possible diquark signatures in the elastic nucleon form factors
Cates, Gordon
2013-10-01
There has been considerable interest in the elastic nucleon form factors ever since the discovery that the proton form-factor ratio, GEp /GMp , decreases nearly linearly above roughly Q2 = 1 GeV2 . More recent measurements of the neutron form-factor ratio, GEn /GMn , up to 3 . 4 GeV2 have made it possible to constrain calculations using both proton and neutron data in the Q2 regime where the interesting behavior of the proton was first observed. Calculations based on QCD's Dyson-Schwinger equations, as well as certain relativistic constituent quark models, suggest that the observed behavior is related to the importance of diquark degrees of freedom. To understand this connection, it is particularly useful to consider the flavor-separated form factors, which can be extracted by combining proton and neutron data, and assuming charge symmetry. Distinctly different behavior is seen for the u - and d - quarks. The behaviors of the different quark flavors and the connection to diquarks can also be understood using naive scaling arguments, although this approach has yet to be made more rigorous. This talk will discuss how measurements of the nucleon form factors at high Q2 provides a rich opportunity to better understand the structure of the nucleon.
Roy-Steiner-equation analysis of pion-nucleon scattering
Hoferichter, Martin; Kubis, Bastian; Meißner, Ulf-G
2015-01-01
We review the structure of Roy-Steiner equations for pion-nucleon scattering, the solution for the partial waves of the t-channel process $\\pi\\pi\\to \\bar N N$, as well as the high-accuracy extraction of the pion-nucleon S-wave scattering lengths from data on pionic hydrogen and deuterium. We then proceed to construct solutions for the lowest partial waves of the s-channel process $\\pi N\\to \\pi N$ and demonstrate that accurate solutions can be found if the scattering lengths are imposed as constraints. Detailed error estimates of all input quantities in the solution procedure are performed and explicit parameterizations for the resulting low-energy phase shifts as well as results for subthreshold parameters and higher threshold parameters are presented. Furthermore, we discuss the extraction of the pion-nucleon $\\sigma$-term via the Cheng-Dashen low-energy theorem, including the role of isospin-breaking corrections, to obtain a precision determination consistent with all constraints from analyticity, unitarity...
Stylized features of single-nucleon momentum distributions
Vanhalst, Maarten; Ryckebusch, Jan
2014-01-01
[Background:] Nuclear short-range correlations (SRC) typically manifest themselves in the tail parts of the single-nucleon momentum distributions. [Purpose:] To develop an approximate flexible method for computing the single-nucleon momentum distributions throughout the whole mass table, thereby including the majority of the effects of SRC. To use this method to study the mass and isospin dependence of SRC. [Method:] The low-order cluster approximation (LCA) adopted in this work, corrects mean-field models for correlations by shifting the complexity induced by the SRC from the wave functions to the operators. Due to the local character of the SRC, it is argued that the expansion of these operators can be truncated to a low order. [Results:] After inclusion of the central and tensor correlations, the LCA can generate the SRC-related features of the single-nucleon momentum distribution like the high-momentum tails. These are dominated by correlations operating on mean-field pairs with vanishing relative radial ...
Latent structures of female sexual functioning.
Carvalho, Joana; Vieira, Armando Luís; Nobre, Pedro
2012-08-01
For the last three decades, male and female sexual responses have been conceptualized as similar, based on separated and sequential phases as proposed by the models of Masters and Johnson (1966) and Kaplan (1979) model. However, there is a growing debate around the need to conceptualize female sexual response and the classification of sexual dysfunction in women, in view of the upcoming editions of the DSM and ICD. The aim of this study was to test, using structural equation modeling, five conceptual, alternative models of female sexual function, using a sample of women with sexual difficulties and a sample of women without sexual problems. A total of 1993 Portuguese women participated in the study and completed a modified version of the Female Sexual Function Index. Findings suggested a four-factor solution as the model that best fit the data regarding women presenting sexual difficulties: (1) desire/arousal; (2) lubrication; (3) orgasm; (4) pain/vaginismus. In relation to sexually healthy women, the best model was a five-factor solution comprising of (1) desire; (2) arousal; (3) lubrication; (4) orgasm; and (5) pain/vaginismus. Discriminant validity between factors was supported, suggesting that these dimensions measure distinct phenomena. Model fit to the data significantly decreased in both samples, as models began to successively consider greater levels of overlap among phases of sexual function, towards a single-factor solution. By suggesting the overlap between pain and vaginismus, results partially support the new classification that is currently being discussed regarding DSM-5. Additionally, results on the relationship between sexual desire and arousal were inconclusive as sexually healthy women were better characterized by a five-factor model that considered the structural independence among these factors, whereas women with sexual difficulties better fit with a four-factor model merging sexual desire and subjective sexual arousal.
Measurement of Neutrino-Nucleon Neutral-Current Elastic Scattering Cross-section at SciBooNE
Energy Technology Data Exchange (ETDEWEB)
Takei, Hideyuki [Tokyo Inst. of Technology (Japan)
2009-02-01
In this thesis, results of neutrino-nucleon neutral current (NC) elastic scattering analysis are presented. Neutrinos interact with other particles only with weak force. Measurement of cross-section for neutrino-nucleon reactions at various neutrino energy are important for the study of nucleon structure. It also provides data to be used for beam flux monitor in neutrino oscillation experiments. The cross-section for neutrino-nucleon NC elastic scattering contains the axial vector form factor G_{A}(Q^{2}) as well as electromagnetic form factors unlike electromagnetic interaction. G_{A} is propotional to strange part of nucleon spin (Δs) in Q^{2} → 0 limit. Measurement of NC elastic cross-section with smaller Q^{2} enables us to access Δs. NC elastic cross-sections of neutrino-nucleon and antineutrino-nucleon were measured earlier by E734 experiment at Brookheaven National Laboratory (BNL) in 1987. In this experiment, cross-sections were measured in Q^{2} > 0.4 GeV^{2} region. Result from this experiment was the only published data for NC elastic scattering cross-section published before our experiment. SciBooNE is an experiment for the measurement of neutrino-nucleon scattering cross-secitons using Booster Neutrino Beam (BNB) at FNAL. BNB has energy peak at 0.7 GeV. In this energy region, NC elastic scattering, charged current elastic scattering, charged current pion production, and neutral current pion production are the major reaction branches. SciBar, electromagnetic calorimeter, and Muon Range Detector are the detectors for SciBooNE. The SciBar consists of finely segmented scintillators and 14336 channels of PMTs. It has a capability to reconstruct particle track longer than 8 cm and separate proton from muons and pions using energy deposit information. Signal of NC elastic scattering is a single proton track. In vp → vp process, the recoil proton is detected. On the other hand, most of vn → vn is
SPHINX v 1.1 Monte Carlo Program for Polarized Nucleon-Nucleon Collisions (update)
Güllenstern, S; Górnicki, P; Mankiewicz, L; Schäfer, A; Güllenstern, Stefan; Martin, Oliver; Gornicki, Pawel; Mankiewicz, Lech; Schäfer, Andreas
1996-01-01
We present the updated long write-up for version 1.1 of the SPHINX Monte Carlo. The program can be used to simulate polarized nucleon - nucleon collisions at high energies. Spins of colliding particles are taken into account. The program allows the calculation of cross sections for various processes.
Nucleon-Nucleon Phase Shifts in the Extended Quark-Delocalization Colour-Screening Model
Institute of Scientific and Technical Information of China (English)
LU Xi-Feng; PING Jia-Lun; WANG Fan
2003-01-01
An alternative method is applied to the study of nucleon-nucleon scattering phase shifts within the framework of the extended quark demoralization colour-screening model, in which the one-pion exchange with short-range cutoff is included.
Quark Mass Dependence of Nucleon Magnetic Moment and Charge Radii
Institute of Scientific and Technical Information of China (English)
MA Wei-Xing; ZHOU Li-Juan; GU Yun-Ting; PING Rong-Gang
2005-01-01
Understanding hadron structure within the framework of QCD is an extremely challenging problem. Our purpose here is to explain the model-independent consequences of the approximated chiral symmetry of QCD for two famous results concerning the quark structure of the nucleon. We show that both the apparent success of the constituent quark model in reproducing the ratio of proton to neutron magnetic moments and the apparent success of the Foldy term in reproducing the observed charge radius of the neutron are coincidental. That is, a relatively small change of the current quark mass would spoil both results.
FSI corrections for near threshold meson production in nucleon-nucleon collisions
Moalem, A; Gedalin, E
1995-01-01
A procedure is proposed which accounts for final state interaction corrections for near threshold meson production in nucleon-nucleon scattering. In analogy with the Watson-Migdal approximation, it is shown that in the limit of extremely strong final state effects, the amplitude factorizes into a primary production amplitude and an elastic scattering amplitude describing a 3 \\to 3 transition. This amplitude determines the energy dependence of the reaction cross section near the reaction threshold almost solely. The approximation proposed satisfies the Fermi-Watson theorem and the coherence formalism. Application of this procedure to meson production in nucleon-nucleon scattering shows that, while corrections due to the meson-nucleon interaction are small for s-wave pion production, they are crucial for reproducing the energy dependence of the \\eta production cross section.
Isospin mixing in the nucleon and 4He and the nucleon strange electric form factor
Viviani, M; Kievsky, A; Kubis, B; Lewis, R; Marcucci, L E; Rosati, S; Schiavilla, R
2007-01-01
In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in 4He(\\vec e,e')4He experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4He. We examine this issue in the present letter. Isospin admixtures in the nucleon are determined in chiral perturbation theory, while those in 4He are derived from nuclear interactions, including explicit ISB terms. A careful analysis of the model dependence in the resulting predictions for the nucleon and nuclear ISB contributions to the asymmetry is carried out. We conclude that, at the low momentum transfers of interest in recent measurements reported by the HAPPEX collaboration at Jefferson Lab, these contributions are of comparable magnitude to those associated with strangeness components in the nucleon electric form factor.
Bedlinskiy, I; Niccolai, S; Stoler, P; Adhikari, K P; Aghasyan, M; Amaryan, M J; Anghinolfi, M; Avakian, H; Baghdasaryan, H; Ball, J; Baltzell, N A; Battaglieri, M; Bennett, R P; Biselli, A S; Bookwalter, C; Boiarinov, S; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Contalbrigo, M; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Doughty, D; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Fleming, J A; Forest, T A; Garçon, M; Gevorgyan, N; Giovanetti, K L; Girod, F X; Gohn, W; Gothe, R W; Graham, L; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jo, H S; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, F J; Koirala, S; Kubarovsky, A; Kuhn, S E; Kuleshov, S V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I J D; Mao, Y; Markov, N; Martinez, D; Mayer, M; McKinnon, B; Meyer, C A; Mineeva, T; Mirazita, M; Mokeev, V; Moutarde, H; Munevar, E; Camacho, C Munoz; Nadel-Turonski, P; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Pappalardo, L L; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Pereira, S Anefalos; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Rossi, P; Sabatié, F; Saini, M S; Salgado, C; Saylor, N; Schott, D; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tian, Ye; Tkachenko, S; Ungaro, M; Vineyard, M F; Vlassov, A; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zachariou, N; Zhang, J; Zhao, Z W; Zonta, I
2012-01-01
Exclusive $\\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\\phi_\\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\\sigma_T +\\epsilon \\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\\sigma_T +\\epsilon \\sigma_L$ and fails to account for $\\sigma_{TT}$ and $\\sigma_{LT}$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm ...
Energy Technology Data Exchange (ETDEWEB)
Bedlinskiy, Ivan; Niccolai, Silvia; Stoler, Paul; Adhikari, Krishna; Aghasyan, Mher; Amaryan, Moskov; Anghinolfi, Marco; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bennett, Robert; Biselli, Angela; Bookwalter, Craig; Boyarinov, Sergey; Briscoe, William; Brooks, Williams; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Contalbrigo, Marco; Crede, Volker; D& #x27; Angelo, Annalisa; Daniel, Aji; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fegan, Stuart; Fleming, Jamie; Forest, Tony; Garcon, Michel; Gevorgyan, Nerses; Giovanetti, Kevin; Girod, Francoi-Xavier; Gohn, Wesley; Gothe, Ralf; Graham, Lewis; Griffioen, Keith; Guegan, Baptiste; Guidal, Michel; Guo, Lei; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Heddle, David; Hicks, Kenneth; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Jo, Hyon-Suk; Joo, Kyungseon; Keller, Dustin; Khanddaker, Mahbubul; Khertarpal, Puneet; Kim, Andrey; Kim, Wooyoung; Klein, Franz; Koirala, Suman; Kubarovsky, A; Kuhn, Sebastian; Kuleshov, Sergey; Kvaltine, Nicholas; Livingston, Kenneth; Lu, Haiyun; MacGregor, Ian; Mao, Yuqing; Markov, Nikolai; Martinez, D; Mayer, Michael; McKinnon, Bryan; Meyer, Curtis; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Moutarde, Herve; Munevar Espitia, Edwin; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niculescu, Gabriel; Niculescu, Maria-Ioana; Osipenko, Mikhail; Ostrovidov, Alexander; Pappalardo, Luciano; Permuzyan, Rafayel; Park, Kijun; Park, Sungkyun; Pasyuk, Eugene; Pereira, Sergio; Phelps, Evan; Pisano, Silvia; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Prok, Yelena; Protopopescu, Dan; Puckett, Andrew; Raue, Brian; Ricco, Giovanni; Rimal, Dipak; Ripani, Marco; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Saylor, Nicholas; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Seraydaryan, Heghine; Sharabian, Youri; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Samuel; Strauch, Steffen; Taiuti, Mauro; Tang, Wei; Taylor, Charles; Tian, Ye; Tkachenko, Svyatoslav; Ungaro, Maurizio; Vineyard, Michael; Vlasov, Alexander; Voskanyan, Hakob; Voutier, Eric; Walford, Natalie; Watts, Daniel; Weinstein, Lawrence; Weygan, Dennis; Wood, Michael; Zachariou, Nicholas; Zhang, Jixie; Zhao, Zhiwen
2012-09-01
Exclusive $\\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\\phi_\\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\\sigma_T +\\epsilon \\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\\sigma_T +\\epsilon \\sigma_L$ and fails to account for $\\sigma_{TT}$ and $\\sigma_{LT}$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive $\\pi^0$ electroproduction offers direct experimental access to the transversity GPDs.
Structural and functional diversity of desmosomes.
Harmon, Robert M; Green, Kathleen J
2013-12-01
Desmosomes anchor intermediate filaments at sites of cell contact established by the interaction of cadherins extending from opposing cells. The incorporation of cadherins, catenin adaptors, and cytoskeletal elements resembles the closely related adherens junction. However, the recruitment of intermediate filaments distinguishes desmosomes and imparts a unique function. By linking the load-bearing intermediate filaments of neighboring cells, desmosomes create mechanically contiguous cell sheets and, in so doing, confer structural integrity to the tissues they populate. This trait and a well-established role in human disease have long captured the attention of cell biologists, as evidenced by a publication record dating back to the mid-1860s. Likewise, emerging data implicating the desmosome in signaling events pertinent to organismal development, carcinogenesis, and genetic disorders will secure a prominent role for desmosomes in future biological and biomedical investigations.
Structural and Functional Views of Mechatronic Products
DEFF Research Database (Denmark)
Nielsen, Kjeld; Petersen, Thomas Ditlev; Jørgensen, Kaj Asbjørn
2011-01-01
The development and subsequent production of industrial products are often complicated tasks. The complication increases with combined product as mechatronic products and is further complicated when large variety is required. Modularity is often used to achieve optimum in these complications both...... in the costumer view as well in the production view. In this paper, the relationships in mechatronic products between the functional and structural levels are explored in relation to modularity. A list of commonly used module drivers is presented and a qualitative survey is used to explore significance...... of influence on these module drivers when applying mechatronic product technology and view levels. The result is summarized in a list of which drivers should be addressed in a mechatronic product approach to modularity. Keywords:...
Structure-function relationships in calpains.
Campbell, Robert L; Davies, Peter L
2012-11-01
Calpains are a family of complex multi-domain intracellular enzymes that share a calcium-dependent cysteine protease core. These are not degradative enzymes, but instead carry out limited cleavage of target proteins in response to calcium signalling. Selective cutting of cytoskeletal proteins to facilitate cell migration is one such function. The two most abundant and extensively studied members of this family in mammals, calpains 1 and 2, are heterodimers of an isoform-specific 80 kDa large subunit and a common 28 kDa small subunit. Structures of calpain-2, both Ca2+-free and bound to calpastatin in the activated Ca2+-bound state, have provided a wealth of information about the enzyme's structure-function relationships and activation. The main association between the subunits is the pairing of their C-terminal penta-EF-hand domains through extensive intimate hydrophobic contacts. A lesser contact is made between the N-terminal anchor helix of the large subunit and the penta-EF-hand domain of the small subunit. Up to ten Ca2+ ions are co-operatively bound during activation. The anchor helix is released and individual domains change their positions relative to each other to properly align the active site. Because calpains 1 and 2 require ~30 and ~350 μM Ca2+ ions for half-maximal activation respectively, it has long been argued that autoproteolysis, subunit dissociation, post-translational modifications or auxiliary proteins are needed to activate the enzymes in the cell, where Ca2+ levels are in the nanomolar range. In the absence of robust support for these mechanisms, it is possible that under normal conditions calpains are transiently activated by high Ca2+ concentrations in the microenvironment of a Ca2+ influx, and then return to an inactive state ready for reactivation.
Coupled-cluster calculations of nucleonic matter
Hagen, G; Ekström, A; Wendt, K A; Baardsen, G; Gandolfi, S; Hjorth-Jensen, M; Horowitz, C J
2014-01-01
Background: The equation of state (EoS) of nucleonic matter is central for the understanding of bulk nuclear properties, the physics of neutron star crusts, and the energy release in supernova explosions. Purpose: This work presents coupled-cluster calculations of infinite nucleonic matter using modern interactions from chiral effective field theory (EFT). It assesses the role of correlations beyond particle-particle and hole-hole ladders, and the role of three-nucleon-forces (3NFs) in nuclear matter calculations with chiral interactions. Methods: This work employs the optimized nucleon-nucleon NN potential NNLOopt at next-to-next-to leading-order, and presents coupled-cluster computations of the EoS for symmetric nuclear matter and neutron matter. The coupled-cluster method employs up to selected triples clusters and the single-particle space consists of a momentum-space lattice. We compare our results with benchmark calculations and control finite-size effects and shell oscillations via twist-averaged bound...
Light hypernuclei and hyperon-nucleon interaction
Energy Technology Data Exchange (ETDEWEB)
Carlson, J.; Gibson, B.F.
1990-01-01
Light Hypernuclei are a vital testing ground for our understanding of the Hyperon-Nucleon interaction. We have performed microscopic calculations of four and five-body hypernuclei using the Nijmegen nucleon-nucleon and hyperon-nucleon interactions. Our calculations include explicit Sigma degrees of freedom. These degrees of freedom are quite important since, in contrast to the {Delta} {minus} N mass difference of {approx} 300 MeV, the {Sigma} resonance is only about 80 MeV above the {Lambda}. In addition, although there is no one-pion-exchange in the {Lambda}N diagonal channel, this longest-range term does contribute to the transition {Lambda}N {minus} {Sigma}N interaction. Our variational calculations show that the A=4 spin 0 ground state binding energy is well reproduced by the Nijmegen HN integration, a one-boson exchange model fit to the available scattering data. The spin 1 excited state and the A=5 ground state are strongly underbound, however. We demonstrate the importance of the strong tensor terms of the Nijmegen model, particularly those in the transition channel, in obtaining this result. The limited data currently available for hyperon-nucleon scattering must be greatly improved in order to place reasonable constraints on the interaction. 12 refs., 3 figs., 3 tabs.
Wavelets and Geometric Structure for Function Spaces
Institute of Scientific and Technical Information of China (English)
Qi Xiang YANG
2004-01-01
With Littlewood-Paley analysis, Peetre and Triebel classified, systematically, almost all the usual function spaces into two classes of spaces: Besov spaces (B)s,q p(s ∈ R,0 ＜ p,q ≤∞) and Triebel-Lizorkin spaces (F)s,q p(s∈R,0＜p＜∞,0＜q≤∞); but the structure of dual spaces (D)s,q p of (F)s,q p(s∈R, 0＜p≤1≤q≤∞) is very different from that of Besov spaces or that of Triebel-Lizorkin spaces, and their structure cannot be analysed easily in the Littlewood-Paley analysis. Our main goal is to characterize (D)s,q p (s ∈ R, 0＜p= 1≤q≤∞) in tent spaces with wavelets. By the way, some applications are given: (i) Triebel-Lizorkin spaces for p = ∞ defined by Littlewood-Paley analysis cannot serve as the dual spaces of Triebel-Lizorkin spaces for p = 1; (ii) Some inclusion relations among these above spaces and some relations among(B)o,q1,(F)o,q1 and L1 are studied.
Intrinsically disordered proteins: structural and functional dynamics
Directory of Open Access Journals (Sweden)
Wallin S
2017-02-01
Full Text Available Stefan Wallin Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John’s, NL, Canada Abstract: The classical view holds that proteins fold into essentially unique three-dimensional structures before becoming biologically active. However, studies over the last several years have provided broad and convincing evidence that some proteins do not adopt a single structure and yet are fully functional. These intrinsically disordered proteins (IDPs have been found to be highly prevalent in many genomes, including human, and play key roles in central cellular processes, such as regulation of transcription and translation, cell cycle, and cell signaling. Moreover, IDPs are overrepresented among proteins implicated in disease, including various cancers and neurodegenerative disorders. Intense efforts, by using both experimental and computational approaches, are consequently under way to uncover the molecular mechanisms that underpin the roles of IDPs in biology and disease. This review provides an introduction to the general biophysical properties of IDPs and discusses some of the recent emerging areas in IDP research, including the roles of IDPs in allosteric regulation, regulatory unfolding, and formation of intracellular membrane-less organelles. In addition, recent attempts at therapeutic targeting of IDPs by small molecules, noting in particular that IDPs represent a potentially important source of new drug targets in light of their central role in protein–protein interaction networks, are also reviewed. Keywords: natively unfolded proteins, unstructured proteins, protein folding, protein–protein interaction, cell regulation, signaling, drug development, inhibitors
Structure, Function, and Evolution of Rice Centromeres
Energy Technology Data Exchange (ETDEWEB)
Jiang, Jiming
2010-02-04
The centromere is the most characteristic landmark of eukaryotic chromosomes. Centromeres function as the site for kinetochore assembly and spindle attachment, allowing for the faithful pairing and segregation of sister chromatids during cell division. Characterization of centromeric DNA is not only essential to understand the structure and organization of plant genomes, but it is also a critical step in the development of plant artificial chromosomes. The centromeres of most model eukaryotic species, consist predominantly of long arrays of satellite DNA. Determining the precise DNA boundary of a centromere has proven to be a difficult task in multicellular eukaryotes. We have successfully cloned and sequenced the centromere of rice chromosome 8 (Cen8), representing the first fully sequenced centromere from any multicellular eukaryotes. The functional core of Cen8 spans ~800 kb of DNA, which was determined by chromatin immunoprecipitation (ChIP) using an antibody against the rice centromere-specific H3 histone. We discovered 16 actively transcribed genes distributed throughout the Cen8 region. In addition to Cen8, we have characterized eight additional rice centromeres using the next generation sequencing technology. We discovered four subfamilies of the CRR retrotransposon that is highly enriched in rice centromeres. CRR elements are constitutively transcribed and different CRR subfamilies are differentially processed by RNAi. These results suggest that different CRR subfamilies may play different roles in the RNAi-mediated pathway for formation and maintenance of centromeric chromatin.
The Structural and Functional Organisation of Cognition.
Directory of Open Access Journals (Sweden)
Peter John Snow
2016-10-01
Full Text Available This paper proposes that what have been historically and contemporarily defined as different domains of human cognition are served by one of four functionally- and structurally-distinct areas of the prefrontal cortex. Their contributions to human intelligence are as follows: (a BA9, enables our emotional intelligence, engaging the psychosocial domain, (b BA47, enables our practical intelligence, engaging the material domain, (c BA46 (or BA46-9/46, enables our abstract intelligence, engaging the hypothetical domain and (d BA10, enables our temporal intelligence, engaging in planning within any of the other three domains. Given their unique contribution to human cognition, it is proposed that these areas be called the, social (BA9, material (BA47, abstract (BA46-9/46 and temporal (BA10 mind. The evidence that BA47 participates strongly in verbal and gestural communication suggests that language evolved primarily as a consequence of the extreme selective pressure for practicality; an observation supported by the functional connectivity between BA47 and orbital areas that negatively reinforce lying. It is further proposed that the abstract mind (BA46-9/46 is the primary seat of metacognition charged with creating adaptive behavioral strategies by generating higher-order concepts (hypotheses from lower-order concepts originating both from our perceptual representations and the other three domains of cognition.
The Structural and Functional Organization of Cognition.
Snow, Peter J
2016-01-01
This article proposes that what have been historically and contemporarily defined as different domains of human cognition are served by one of four functionally- and structurally-distinct areas of the prefrontal cortex (PFC). Their contributions to human intelligence are as follows: (a) BA9, enables our emotional intelligence, engaging the psychosocial domain; (b) BA47, enables our practical intelligence, engaging the material domain; (c) BA46 (or BA46-9/46), enables our abstract intelligence, engaging the hypothetical domain; and (d) BA10, enables our temporal intelligence, engaging in planning within any of the other three domains. Given their unique contribution to human cognition, it is proposed that these areas be called the, social (BA9), material (BA47), abstract (BA46-9/46) and temporal (BA10) mind. The evidence that BA47 participates strongly in verbal and gestural communication suggests that language evolved primarily as a consequence of the extreme selective pressure for practicality; an observation supported by the functional connectivity between BA47 and orbital areas that negatively reinforce lying. It is further proposed that the abstract mind (BA46-9/46) is the primary seat of metacognition charged with creating adaptive behavioral strategies by generating higher-order concepts (hypotheses) from lower-order concepts originating from the other three domains of cognition.
Vector Meson Production in Collisions of Nucleons
Brinkmann, K.-Th.; Abdel-Bary, M.; Abdel-Samad, S.; Clement, H.; Doroshkevich, E.; Dshemuchadse, S.; Dutz, H.; Ehrhardt, K.; Erhardt, A.; Eyrich, W.; Filippi, A.; Freiesleben, H.; Fritsch, M.; Georgi, J.; Gillitzer, A.; Gonser, P.; Jäkel, R.; Karsch, L.; Kilian, K.; Koch, H.; Kreß, J.; Kuhlmann, E.; Marcello, S.; Meyer, W.; Michel, P.; Morsch, H. P.; Möller, K.; Mörtel, H.; Naumann, L.; Pinna, L.; Pizzolotto, L.; Roderburg, E.; Schamlott, A.; Schönmeier, P.; Schroeder, W.; Schulte-Wissermann, M.; Sefzick, T.; Steinke, M.; Stinzing, F.; Sun, G. Y.; Ucar, A.; Ullrich, W.; Wagner, G. J.; Wagner, M.; Wilms, A.; Wintz, P.; Wirth, S.; Wüstner, P.; Zupranski, P.
The production of vector mesons in collisions between nucleons is studied in order to address a variety of issues concerning nucleon-nucleon interaction, reaction mechanism and properties of baryons. These studies are summarized with emphasis on the most recent experiments at the Time-of-Flight spectrometer TOF and results obtained at the COoler SYnchrotron COSY in Jülich. While currently the open questions regarding the so-called OZI violation, its relation to the meson exchange picture and the relative importance of contributions to the production mechanism from various channels within this formalism are still unresolved, the present-day experiments hold the potential to clarify the situation greatly. Possible extensions of the experimental program on vector mesons using 4π detection techniques for charged as well as neutral particles, in particular π0, are discussed.
Axial Nucleon form factors from lattice QCD
Alexandrou, C; Carbonell, J; Constantinou, M; Harraud, P A; Guichon, P; Jansen, K; Korzec, T; Papinutto, M
2010-01-01
We present results on the nucleon axial form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length $L=2.1$ fm and $L=2.8$ fm. Cut-off effects are investigated using three different values of the lattice spacings, namely $a=0.089$ fm, $a=0.070$ fm and $a=0.056$ fm. The nucleon axial charge is obtained in the continuum limit and chirally extrapolated to the physical pion mass enabling comparison with experiment.
Precise Determination of Charge Dependent Pion-Nucleon-Nucleon Coupling Constants
Perez, R Navarro; Arriola, E Ruiz
2016-01-01
We undertake a covariance error analysis of the pion-nucleon-nucleon coupling constants from the Granada-2013 np and pp database comprising a total of 6713 scattering data. Assuming a unique pion-nucleon coupling constant we obtain $f^2=0.0761(3)$. The effects of charge symmetry breaking on the $^3P_0$, $^3P_1$ and $^3P_2$ partial waves are analyzed and we find $f_{p}^2 = 0.0759(4)$, $f_{0}^2 = 0.079(1)$ and $f_{c}^2 = 0.0763(6)$ with minor correlations among the coupling constants. We successfully test normality for the residuals of the fit.
Shin, Dong Hae; Hou, Jingtong; Chandonia, John-Marc; Das, Debanu; Choi, In-Geol; Kim, Rosalind; Kim, Sung-Hou
2007-09-01
Advances in sequence genomics have resulted in an accumulation of a huge number of protein sequences derived from genome sequences. However, the functions of a large portion of them cannot be inferred based on the current methods of sequence homology detection to proteins of known functions. Three-dimensional structure can have an important impact in providing inference of molecular function (physical and chemical function) of a protein of unknown function. Structural genomics centers worldwide have been determining many 3-D structures of the proteins of unknown functions, and possible molecular functions of them have been inferred based on their structures. Combined with bioinformatics and enzymatic assay tools, the successful acceleration of the process of protein structure determination through high throughput pipelines enables the rapid functional annotation of a large fraction of hypothetical proteins. We present a brief summary of the process we used at the Berkeley Structural Genomics Center to infer molecular functions of proteins of unknown function.
Energy Technology Data Exchange (ETDEWEB)
Kim, Sung-Hou; Shin, Dong Hae; Hou, Jingtong; Chandonia, John-Marc; Das, Debanu; Choi, In-Geol; Kim, Rosalind; Kim, Sung-Hou
2007-09-02
Advances in sequence genomics have resulted in an accumulation of a huge number of protein sequences derived from genome sequences. However, the functions of a large portion of them cannot be inferred based on the current methods of sequence homology detection to proteins of known functions. Three-dimensional structure can have an important impact in providing inference of molecular function (physical and chemical function) of a protein of unknown function. Structural genomics centers worldwide have been determining many 3-D structures of the proteins of unknown functions, and possible molecular functions of them have been inferred based on their structures. Combined with bioinformatics and enzymatic assay tools, the successful acceleration of the process of protein structure determination through high throughput pipelines enables the rapid functional annotation of a large fraction of hypothetical proteins. We present a brief summary of the process we used at the Berkeley Structural Genomics Center to infer molecular functions of proteins of unknown function.
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.
Short range correlations between nucleons in finite nuclei
Institute of Scientific and Technical Information of China (English)
ZHOU Li-Juan; MA Wei-Xing
2008-01-01
The short-range correlation between nucleons in finite nuclei is investigated in high energy protonnucleus and α-nucleus elastic scattering in the framework of Glauber multiple scattering theory without any free parameters. The effects on the p-4He and 4He-12C elastic scattering, and in particular on the proton elastic scattering off hallo-like nuclei, 6,8He, are estimated. Our calculations show that the short-range correlations play an important role in reproducing experimental data and could be also thought of as being possible origin and nature of halo-like phenomena in the nuclear structure. More accurate calculations along this line are needed.
Anisotropic nanomaterials: structure, growth, assembly, and functions.
Sajanlal, Panikkanvalappil R; Sreeprasad, Theruvakkattil S; Samal, Akshaya K; Pradeep, Thalappil
2011-01-01
Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications.
Anisotropic nanomaterials: structure, growth, assembly, and functions
Directory of Open Access Journals (Sweden)
Panikkanvalappil R. Sajanlal
2011-02-01
Full Text Available Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D, two-dimensional (2D, and three-dimensional (3D arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications.
A light front quark-diquark model for the nucleons
Maji, Tanmay
2016-01-01
We present a quark-diquark model for the nucleons where the light front wave functions are constructed from the soft-wall AdS/QCD prediction. The model is consistent with quark counting rule and Drell-Yan-West relation. The model reproduces the scale evolution of unpolarized PDF of proton for a wide range of energy scale. Helicity and transversity distributions for the proton predicted in this model agree with phenomenological fits. The axial and tensor charges are also shown to agree with the experimental data. The model can be used to evaluate distributions like GPDS, TMDs etc. and their scale evolutions.
Energy Technology Data Exchange (ETDEWEB)
Riad Suleiman
1999-10-01
The deuteron elastic structure functions, A(Q{sup 2}) and B(Q{sup 2}), have been extracted from cross section measurements of elastic electron-deuteron scattering in coincidence using the Continuous Electron Beam Accelerator and Hall A Facilities of Jefferson Laboratory. Incident electrons were scattered off a high-power cryogenic deuterium target. Scattered electrons and recoil deuterons were detected in the two High Resolution Spectrometers of Hall A. A(Q{sup 2}) was extracted from forward angle cross section measurements in the squared four-momentum transfer range 0.684 ≤ Q{sup 2} ≤ 5.90 (GeV/c){sup 2}. B(Q{sup 2}) was determined by means of a Rosenbluth separation in the range 0.684 ≤ Q{sup 2} ≤ 1.325 (GeV/c){sup 2}. The data are compared to theoretical models based on the impulse approximation with the inclusion of meson-exchange currents and to predictions of quark dimensional scaling and perturbative quantum chromodynamics. The results are expected to provide insights into the transition from meson-nucleon to quark-gluon descriptions of the nuclear two-body system.
New lessons from the nucleon mass, lattice QCD and heavy baryon chiral perturbation theory
Walker-Loud, A
2008-01-01
I will review heavy baryon chiral perturbation theory for the nucleon delta degrees of freedom and then examine the recent dynamical lattice calculations of the nucleon mass from the BMW, ETM, JLQCD, LHP, MILC, NPLQCD, PACS-CS, QCDSF/UKQCD and RBC/UKQCD Collaborations. Performing the chiral extrapolations of these results, one finds remarkable agreement with the physical nucleon mass, from each lattice data set. However, a careful examination of the lattice data and the resulting extrapolation functions reveals some unexpected results, serving to highlight the significant challenges in performing chiral extrapolations of baryon quantities. All the N_f=2+1 dynamical results can be quantitatively described by theoretically unmotivated fit function linear in the pion mass with m_pi ~ 750 -190 MeV. When extrapolated to the physical point, the results are in striking agreement with the physical nucleon mass. I will argue that knowledge of each lattice datum of the nucleon mass is required at the 1-2% level, includ...
Chiral effective field theory analysis of hadronic parity violation in few-nucleon systems
Viviani, M.; Baroni, A.; Girlanda, L.; Kievsky, A.; Marcucci, L. E.; Schiavilla, R.
2014-06-01
Background: Weak interactions between quarks induce a parity-violating (PV) component in the nucleon-nucleon potential, whose effects are currently being studied in a number of experiments involving few-nucleon systems. In the present work, we reconsider the derivation of this PV component within a chiral effective field theory (χEFT) framework. Purpose: The objectives of the present work are twofold. The first is to perform a detailed analysis of the PV nucleon-nucleon potential up to next-to-next-to-leading (N2LO) order in the chiral expansion, in particular, by determining the number of independent low-energy constants (LECs) at N2LO. The second objective is to investigate PV effects in a number of few-nucleon observables, including the p⃗-p longitudinal asymmetry, the neutron spin rotation in n⃗-p and n⃗-d scattering, and the longitudinal asymmetry in the 3He(n⃗,p)3H charge-exchange reaction. Methods: The χEFT PV potential includes one-pion-exchange, two-pion-exchange, and contact terms as well as 1/M (M being the nucleon mass) nonstatic corrections. Dimensional regularization is used to renormalize pion loops. The wave functions for the A =2-4 nuclei are obtained by using strong two- and three-body potentials also derived, for consistency, from χEFT. In the case of the A =3-4 systems, the wave functions are computed by expanding on a hyperspherical harmonics functions basis. Results: We find that the PV potential at N2LO depends on six LECs: the pion-nucleon PV coupling constant hπ1 and five parameters multiplying contact interactions. An estimate for the range of values of the various LECs is provided by using available experimental data, and these values are used to obtain predictions for the other PV observables. Conclusions: The χEFT approach provides a very satisfactory framework to analyze PV effects in few-nucleon systems.
Chiral effective field theory analysis of hadronic parity violation in few-nucleon systems
Energy Technology Data Exchange (ETDEWEB)
Viviani, M. [National Inst. of Nuclear Physics (INFN), Pisa (Italy); Baroni, A. [Old Dominion Univ., Norfolk, VA (United States). Dept. of Physics; Girlanda, L. [Univ. of Salento and INFN-Lecce, Lecce (Italy). Dept. of Mathematical and Physics; Kievsky, A. [National Inst. of Nuclear Physics (INFN), Pisa (Italy); Marcucci, L. E. [Univ. of Pisa (Italy); National Inst. of Nuclear Physics (INFN), Pisa (Italy); Schiavilla, R. [Old Dominion Univ., Norfolk, VA (United States). Dept. of Physics; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2014-06-18
Weak interactions between quarks induce a parity-violating (PV) component in the nucleon-nucleon potential, whose effects are currently being studied in a number of experiments involving few-nucleon systems. In the present work, we reconsider the derivation of this PV component within a chiral effective field theory (${\\chi }$EFT) framework. Purpose: The objectives of the present work are twofold. The first is to perform a detailed analysis of the PV nucleon-nucleon potential up to next-to-next-to-leading (N2LO) order in the chiral expansion, in particular, by determining the number of independent low-energy constants (LECs) at N2LO. The second objective is to investigate PV effects in a number of few-nucleon observables, including the $\\vec{p}$-p longitudinal asymmetry, the neutron spin rotation in n-p and n-d scattering, and the longitudinal asymmetry in the ^{3}He( $\\vec{n}$,p)^{3}H charge-exchange reaction. Methods: The ${\\chi }$EFT PV potential includes one-pion-exchange, two-pion-exchange, and contact terms as well as 1/M (M being the nucleon mass) nonstatic corrections. Dimensional regularization is used to renormalize pion loops. The wave functions for the A=2-4 nuclei are obtained by using strong two- and three-body potentials also derived, for consistency, from ${\\chi }$EFT. In the case of the A=3-4 systems, systems, the wave functions are computed by expanding on a hyperspherical harmonics functions basis. Results: We find that the PV potential at N2LO depends on six LECs: the pion-nucleon PV coupling constant h$1\\atop{π}$ and five parameters multiplying contact interactions. An estimate for the range of values of the various LECs is provided by using available experimental data, and these values are used to obtain predictions for the other PV observables. Conclusions: The ${\\chi }$EFT approach provides a very satisfactory framework to analyze PV effects in few-nucleon systems.
Overview of high-Q2 nucleon form factor program with Super BigBite Spectrometer in JLab's Hall A
Puckett, Andrew; Jefferson Lab Hall A; Super BigBite Spectrometer Collaboration
2017-01-01
The elastic electromagnetic form factors (EMFFs) of the nucleon describe the impact-parameter-space distributions of electric charge and magnetization in the nucleon in the infinite momentum frame. The form factors are among the simplest and most fundamental measurable dynamical quantities describing the nucleon's structure. Precision measurements of the nucleon form factors provide stringent benchmarks testing the most sophisticated theoretical models of the nucleon, as well as ab initio calculations in lattice QCD and continuum non-perturbative QCD calculations based on the Dyson-Schwinger equations. Measurements at momentum transfers Q in the few-GeV range probe the theoretically challenging region of transition between the non-perturbative and perturbative regimes of QCD. The recent upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) to a maximum electron beam energy of 11 GeV will facilitate the measurement of the nucleon helicity-conserving (F1) and helicity-flip (F2) form factors of both proton and neutron to Q2 > 10 GeV2, In this talk, I will present an overview of the Super BigBite Spectrometer, currently under construction in CEBAF's experimental Hall A, and its physics program of high-Q2 nucleon EMFF measurements. Supported by US DOE award DE-SC0014230.
Charged and Neutral Current Neutrino Induced Nucleon Emission Reactions
Nieves, J; Vacas, M J V
2006-01-01
By means of a Monte Carlo cascade method, to account for the rescattering of the outgoing nucleon, we study the charged and neutral current inclusive one nucleon knockout reactions off nuclei induced by neutrinos. The nucleon emission process studied here is a clear signal for neutral--current neutrino driven reactions, and can be used in the analysis of future neutrino experiments.
A next-to-leading-order QCD analysis of neutrino-iron structure functions at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Seligman, William Glenn [Columbia Univ., New York, NY (United States)
1997-01-01
Nucleon structure functions measured in neutrino-iron and antineutrino-iron charged-current interactions are presented. The data were taken in two high-energy high-statistics runs by the LAB-E detector at the Fermilab Tevatron. Structure functions are extracted from a sample of 950,000 neutrino and 170,000 antineutrino events with neutrino energies from 30 to 360 GeV. The structure functions F_{2} and xF_{3} are compared with the predictions of perturbative Quantum Chromodynamics (PQCD). The combined non-singlet and singlet evolution in the context of PQCD gives value of ΛNLO,(4)/MS = 337 ± 28 (exp.) MeV, which corresponds to α_{S}(M_{Z}^{2}) = 0.119 ± 0.002 (exp.) ± 0.004 (theory), and with a gluon distribution given by xG(x,Q_{0}^{2} = 5GeV^{2}) = (2.22 ± 0.34) x (1 - x)^{4.65±0.68}.
A next-to-leading-order QCD analysis of neutrino-iron structure functions at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Seligman, W.G.
1997-06-01
Nucleon structure functions measured in neutrino-iron and antineutrino-iron charged-current interactions are presented. The data were taken in two high-energy high-statistics runs by the LAB-E detector at the Fermilab Tevatron. Structure functions are extracted from a sample of 950,000 neutrino and 170,000 antineutrino events with neutrino energies from 30 to 360 GeV. The structure functions F{sub 2} and xF{sub 3} are compared with the predictions of perturbative Quantum Chromodynamics (PQCD). The combined non-singlet and singlet evolution in the context of PQCD gives value of {Lambda}NLO,(4)/MS = 337 {+-} 28 (exp.) MeV, which corresponds to {alpha}{sub S}(M{sub Z}{sup 2}) = 0.119 {+-} 0.002 (exp.) {+-} 0.004 (theory), and with a gluon distribution given by xG(x,Q{sub 0}{sup 2} = 5GeV{sup 2}) = (2.22 {+-} 0.34) {times} (1 {minus} x){sup 4.65{+-}0.68}.
Peripheral nucleon-nucleon scattering at fifth order of chiral perturbation theory
Entem, D R; Machleidt, R; Nosyk, Y
2014-01-01
We present the two- and three-pion exchange contributions to the nucleon-nucleon interaction which occur at next-to-next-to-next-to-next-to-leading order (N4LO, fifth order) of chiral effective field theory, and calculate nucleon-nucleon scattering in peripheral partial waves with L>=3 using low-energy constants that were extracted from pi-N analysis at fourth order. While the net three-pion exchange contribution is moderate, the two-pion exchanges turn out to be sizeable and prevailingly repulsive, thus, compensating the excessive attraction characteristic for NNLO and N3LO. As a result, the N4LO predictions for the phase shifts of peripheral partial waves are in very good agreement with the data (with the only exception of the 1F3 wave). We also discuss the issue of the order-by-order convergence of the chiral expansion for the NN interaction.
Institute of Scientific and Technical Information of China (English)
XING Yong-Zhong; HAO Huan-Feng; LIU Xiao-Bin; FANG Yu-Tian; LIU Bao-Yi
2007-01-01
@@ Influences of the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction (MDI) on the isotope scaling are investigated by using the isospin-dependent quantum molecular dynamics model (IQMD). The results show that both the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction affect the isoscaling parameters appreciably and independently. The influence caused by the isospin dependence of two-body collision is relatively larger than that from the MDI in the mean field. Aiming at exploring the implication of isoscaling behaviour, which the statistical equilibrium in the reaction is reached, the statistical properties in the mass distribution and the kinetic energy distribution of the fragments simulated by IQMD are presented.
Nucleon-nucleon scattering at small angles, measured at ANKE-COSY
Bagdasarian, Z.
2016-03-01
The most accepted approach to describe nucleon-nucleon (NN) interaction is the partial wave analysis (PWA), which translates various experimental observables to the common language of the partial waves. The reliable analysis relies not only on the quality experimental data, but also on the measurements of scattering observables over preferably the full angular range. Small angle scattering has been measured for six beam energies between 0.8 and 2.4 GeV using polarized proton beam incident on both proton and deuteron unpolarized targets at COSY-ANKE. This proceeding will report on the published and preliminary results for both pp and pn scattering from this and other recent experiments at ANKE. This study aims to provide the valuable observables to the SAID group in order to improve the phenomenological understanding of the nucleon-nucleon interaction.
Calculation of Nucleon Electromagnetic Form Factors
Renner, D B; Dolgov, D S; Eicker, N; Lippert, T; Negele, J W; Pochinsky, A V; Schilling, K; Lippert, Th.
2002-01-01
The fomalism is developed to express nucleon matrix elements of the electromagnetic current in terms of form factors consistent with the translational, rotational, and parity symmetries of a cubic lattice. We calculate the number of these form factors and show how appropriate linear combinations approach the continuum limit.
Nucleon-decay like signatures of Hylogenesis
Demidov, S V
2015-01-01
We consider nucleon-decay like signatures of the hylogenesis, a variant of antibaryonic dark matter model. For the interaction between visible and dark matter sectors through the neutron portal, we calculate rates of dark matter scatterings off neutron which mimic neutron-decay processes $n\\to \
Strong decays of nucleon and $\\Delta$ resonances
Bijker, R
1996-01-01
We study the strong couplings of the nucleon and delta resonances in a collective model. In the ensuing algebraic treatment we derive closed expressions for decay widths which are used to analyze the experimental data for strong decays into the pion and eta channels.
Structure and function of the archaeal exosome.
Evguenieva-Hackenberg, Elena; Hou, Linlin; Glaeser, Stefanie; Klug, Gabriele
2014-01-01
The RNA-degrading exosome in archaea is structurally very similar to the nine-subunit core of the essential eukaryotic exosome and to bacterial polynucleotide phosphorylase (PNPase). In contrast to the eukaryotic exosome, PNPase and the archaeal exosome exhibit metal ion-dependent, phosphorolytic activities and synthesize heteropolymeric RNA tails in addition to the exoribonucleolytic RNA degradation in 3' → 5' direction. The archaeal nine-subunit exosome consists of four orthologs of eukaryotic exosomal subunits: the RNase PH-domain-containing subunits Rrp41 and Rrp42 form a hexameric ring with three active sites, whereas the S1-domain-containing subunits Rrp4 and Csl4 form an RNA-binding trimeric cap on the top of the ring. In vivo, this cap contains Rrp4 and Csl4 in variable amounts. Rrp4 confers poly(A) specificity to the exosome, whereas Csl4 is involved in the interaction with the archaea-specific subunit of the complex, the homolog of the bacterial primase DnaG. The archaeal DnaG is a highly conserved protein and its gene is present in all sequenced archaeal genomes, although the exosome was lost in halophilic archaea and some methanogens. In exosome-containing archaea, DnaG is tightly associated with the exosome. It functions as an additional RNA-binding subunit with poly(A) specificity in the reconstituted exosome of Sulfolobus solfataricus and enhances the degradation of adenine-rich transcripts in vitro. Not only the RNA-binding cap but also the hexameric Rrp41-Rrp42 ring alone shows substrate selectivity and prefers purines over pyrimidines. This implies a coevolution of the exosome and its RNA substrates resulting in 3'-ends with different affinities to the exosome.
Three-pion exchange a gap in the nucleon-nucleon potential
Pupin, J C
1999-01-01
The leading contribution to the three-pion exchange nucleon-nucleon potential is calculated in the framework of chiral symmetry. It has pseudoscalar and axial components and is dominated by the former, which has a range of about 1.5 fm and tends to enhance the OPEP. The strength of this force does not depend on the pion mass and hence it survives in the chiral limit.
Nuclear effects on axions emission rates from nucleon-nucleon bremsstrahlung
Pastrav, B.; Scafes, A. C.
2010-11-01
The rates of axion emissions by nucleon-nucleon bremsstrahlung from neutron stars obtained with the inclusion of the full angular momentum contribution from a nuclear one-pion-exchange potential (OPEP), are studied in different conditions of temperature and degeneracy in both, non degenerate (ND) and degenerate (D) regimes. The comparison with the previous results obtained in literature, where only the high momentum limit of the OPEP expressions are used, is done and the differences discussed.
Energy Technology Data Exchange (ETDEWEB)
Szpigel, S. [Centro de Ciencias e Humanidades, Universidade Presbiteriana Mackenzie, Sao Paulo, SP (Brazil); Timoteo, V.S. [Faculdade de Tecnologia, Universidade Estadual de Campinas, Limeira, SP (Brazil); Duraes, F. de O [Centro de Ciencias e Humanidades, Universidade Presbiteriana Mackenzie, Sao Paulo, SP (Brazil)
2010-02-15
In this work we study the Similarity Renormalization Group (SRG) evolution of effective nucleon-nucleon (NN) interactions derived using the Subtracted Kernel Method (SKM) approach. We present the results for the phaseshifts in the {sup 1}S{sub 0} channel calculated using a SRG potential evolved from an initial effective potential obtained by implementing the SKM scheme for the leading-order NN interaction in chiral effective field theory (ChEFT).
The one-pion-exchange potential in the three-body model of nucleon-nucleon scattering
Garcilazo, Humberto
1981-02-01
We derive the one-pion-exchange potential in the three-body model of nucleon-nucleon scattering in which the nucleon is treated as a bound state of a pion and a nucleon, and show that it has the same form as the usual Yukawa OPEP derived from field theory, except that its range is energy dependent and it becomes complex above the pion-production threshold.
Probing short-range nucleon-nucleon interactions with an Electron-Ion Collider
Miller, Gerald A; Venugopalan, Raju
2015-01-01
We derive the cross-section for exclusive vector meson production in high energy deeply inelastic scattering off a deuteron target that disintegrates into a proton and a neutron carrying large relative momentum in the final state. This cross-section can be expressed in terms of a novel gluon Transition Generalized Parton Distribution (T-GPD); the hard scale in the final state makes the T-GPD sensitive to the short distance nucleon-nucleon interaction. We perform a toy model computation of this process in a perturbative framework and discuss the time scales that allow the separation of initial and final state dynamics in the T-GPD. We outline the more general computation based on the factorization suggested by the toy computation: in particular, we discuss the relative role of "point-like" and "geometric" Fock configurations that control the parton dynamics of short range nucleon-nucleon scattering. With the aid of exclusive $J/\\Psi$ production data at HERA, as well as elastic nucleon-nucleon cross-sections, w...
Three-Nucleon Bound States and the Wigner-SU(4) Limit
Vanasse, Jared; Phillips, Daniel R.
2017-03-01
We examine the extent to which the properties of three-nucleon bound states are well-reproduced in the limit that nuclear forces satisfy Wigner's SU(4) (spin-isospin) symmetry. To do this we compute the charge radii up to next-to-leading order (NLO) in an effective field theory that is an expansion in powers of R/ a, with R the range of the nuclear force and a the nucleon-nucleon (N N) scattering lengths. In the Wigner-SU(4) limit, the triton and helium-3 point charge radii are equal. At NLO in the range expansion both are 1.66 fm. Adding the first-order corrections due to the breaking of Wigner symmetry in the N N scattering lengths gives a ^3{H} point charge radius of 1.58 fm, which is remarkably close to the experimental number, 1.5978± 0.040 fm (Angeli and Marinova in At Data Nucl Data Tables 99:69-95, 2013). For the ^3{He} point charge radius we find 1.70 fm, about 4% away from the experimental value of 1.77527± 0.0054 fm (Angeli and Marinova 2013). We also examine the Faddeev components that enter the tri-nucleon wave function and find that an expansion of them in powers of the symmetry-breaking parameter converges rapidly. Wigner's SU(4) symmetry is thus a useful starting point for understanding tri-nucleon bound-state properties.
Constituent quarks and the gluonic contribution to the spin of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Eldahoumi, Gamal
2009-01-15
The internal structure of the nucleon is more complicated than expected in a simple quark model. In particular, the portion of the nucleon spin carried by the spins of the quarks is not, as expected, of the order of one, but according to the experimental data much smaller. In this thesis we study the spin structure of the proton in quantum chromodynamics. The constituent quark model, based on SU(6), predicts that the spin of the proton should be carried by the quarks, in disagreement with the experiments. It appears strange, that the theoretical model works so well for the magnetic moments of the nucleons, but not for the spin, although the spin and the magnetic moments are closely related to each other. We shall resolve this problem by assuming that the constituent quarks have an internal structure on their own. Thus a constituent quark has a dynamical structure, and we can introduce notions like the quark or gluon distributions inside a constituent quark. In the light of new experimental data from HERMES, COMPASS, JLab, and RHIC-spin, the current status of our knowledge of the spin structure is discussed in the two theoretical frameworks: the naive parton model, and the QCD evolved parton model. QCD a is successful theory, both in perturbative and non-perturbative regions, but the spin of the nucleon still needs to be explained within QCD. (orig.)
Nucleon polarisabilities at and beyond physical pion masses
Energy Technology Data Exchange (ETDEWEB)
Griesshammer, Harald W. [The George Washington University, Institute for Nuclear Studies, Department of Physics, Washington, DC (United States); McGovern, Judith A. [The University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom); Phillips, Daniel R. [Ohio University, Department of Physics and Astronomy and Institute of Nuclear and Particle Physics, Athens, OH (United States)
2016-05-15
We examine the results of Chiral Effective Field Theory (χEFT) for the scalar- and spin-dipole polarisabilities of the proton and neutron, both for the physical pion mass and as a function of m{sub π}. This provides chiral extrapolations for lattice QCD polarisability computations. We include both the leading and subleading effects of the nucleon's pion cloud, as well as the leading ones of the Δ (1232)-resonance and its pion cloud. The analytic results are complete at N{sup 2}LO in the δ counting for pion masses close to the physical value, and at leading order for pion masses similar to the Delta-nucleon mass splitting. In order to quantify the truncation error of our predictions and fits as 68% degree-of-belief intervals, we use a Bayesian procedure recently adapted to EFT expansions. At the physical point, our predictions for the spin polarisabilities are, within respective errors, in good agreement with alternative extractions using experiments and dispersion-relation theory. At larger pion masses we find that the chiral expansion of all polarisabilities becomes intrinsically unreliable as m{sub π} approaches about 300 MeV -as has already been seen in other observables. χEFT also predicts a substantial isospin splitting above the physical point for both the electric and magnetic scalar polarisabilities; and we speculate on the impact this has on the stability of nucleons. Our results agree very well with emerging lattice computations in the realm where χEFT converges. Curiously, for the central values of some of our predictions, this agreement persists to much higher pion masses. We speculate on whether this might be more than a fortuitous coincidence. (orig.)
Roy-Steiner equations for pion-nucleon scattering
Ditsche, C.; Hoferichter, M.; Kubis, B.; Meißner, U.-G.
2012-06-01
Starting from hyperbolic dispersion relations, we derive a closed system of Roy-Steiner equations for pion-nucleon scattering that respects analyticity, unitarity, and crossing symmetry. We work out analytically all kernel functions and unitarity relations required for the lowest partial waves. In order to suppress the dependence on the high energy regime we also consider once- and twice-subtracted versions of the equations, where we identify the subtraction constants with subthreshold parameters. Assuming Mandelstam analyticity we determine the maximal range of validity of these equations. As a first step towards the solution of the full system we cast the equations for the π π to overline N N partial waves into the form of a Muskhelishvili-Omnès problem with finite matching point, which we solve numerically in the single-channel approximation. We investigate in detail the role of individual contributions to our solutions and discuss some consequences for the spectral functions of the nucleon electromagnetic form factors.
The structural basis of nuclear function.
Jackson, D A; Cook, P R
1995-01-01
Most models for transcription and replication involve polymerases that track along the template. We review here experiments that suggest an alternative in which polymerization occurs as the template slides past a polymerase fixed to a large structure in the eukaryotic nucleus--a "factory" attached to a nucleoskeleton. This means that higher-order structure dictates how and when DNA is replicated or transcribed.
The CP-odd nucleon interaction and the value of T-violation in nuclei
Energy Technology Data Exchange (ETDEWEB)
Gudkov, V.P.
1997-06-01
The relations between the value of T- and P-violating correlations in neutron scattering and different models of CP violation are discussed. It is shown that a specific structure of CP-odd nucleon interactions gives the possibility to obtain the essential information about CP-odd interaction at the quark-gluon level from nuclear experimental data. The up-to-date estimations for CP-violating nucleon coupling constants show that each class of CP-violating models can give a measurable effect for the neutron scattering experiments. 57 refs.
de Teramond, Guy F
2016-01-01
The superconformal algebraic approach to hadronic physics is used to construct a semiclassical effective theory for nucleons which incorporates essential nonperturbative dynamical features, such as the emergence of a confining scale and the Regge resonance spectrum. Relativistic bound-state equations for nucleons follow from the extension of superconformal quantum mechanics to the light front and its holographic embedding in a higher dimensional gravity theory. Superconformal algebra has been used elsewhere to describe the connections between the light mesons and baryons, but in the present context it relates the fermion positive and negative chirality states and uniquely determines the confinement potential of nucleons. The holographic mapping of multi-quark bound states also leads to a light-front cluster decomposition of form factors for an arbitrary number of constituents. The remarkable analytical structure which follows incorporates the correct scaling behavior at high photon virtualities and also vecto...
de Téramond, Guy F.
2016-10-01
The superconformal algebraic approach to hadronic physics is used to construct a semiclassical effective theory for nucleons which incorporates essential nonperturbative dynamical features, such as the emergence of a confining scale and the Regge resonance spectrum. Relativistic bound-state equations for nucleons follow from the extension of superconformal quantum mechanics to the light front and its holographic embedding in a higher dimensional gravity theory. Superconformal algebra has been used elsewhere to describe the connections between the light mesons and baryons, but in the present context it relates the fermion positive and negative chirality states and uniquely determines the confinement potential of nucleons. The holographic mapping of multi-quark bound states also leads to a light-front cluster decomposition of form factors for an arbitrary number of constituents. The remarkable analytical structure which follows incorporates the correct scaling behavior at high photon virtualities and also vector dominance at low energies.
A Perturbative QCD Analysis of the Nucleon's Pauli Form Factor F_2(Q^2)
Belitsky, A V; Yuan, F; Belitsky, Andrei V.; Ji, Xiangdong; Yuan, Feng
2003-01-01
We perform a perturbative QCD analysis of the nucleon's Pauli form factor $F_2(Q^2)$ in the asymptotically large $Q^2$ limit. We find that the leading contribution to $F_2(Q^2)$ goes like $1/Q^6$, consistent with the well-known folklore. Its coefficient is expressed in terms of an overlap integral involving the leading and subleading light-cone wave functions of the nucleon, the latter describing the quark state with one unit of orbital angular momentum. We estimate the numerical size of the coefficient and comment on the contribution from the end-point region.
Charged Multiplicity Density and Number of Participant Nucleons in Relativistic Nuclear Collisions
Institute of Scientific and Technical Information of China (English)
SA Ben-Hao; CAI Xu; ZHOU Dai-Mei
2003-01-01
The energy and centrality dependencies of charged particle pseudorapidity density in relativistic nuclearcollisions were studied using a hadron and string cascade model, JPCIAE. Both the relativistic p+p experimental dataand the PHOBOS and PHENIX Au+Au data at RHIC energy could be fairly reproduced within the framework ofJPCIAE model and without retuning the model parameters. The predictions for Pb + Pb collisions at the LHC energywere also given. We computed the participant nucleon distributions using different methods. It was found that thenumber of participant nucleons is not a well defined variable both experimentally and theoretically. Thus it may beinappropriate to use the charged particle pseudorapidity density per participant pair .as a function of the number ofparticipant nucleons for distinguishing various theoretical models.
Babenko, V A
2016-01-01
We study relationship between the physical quantities that characterize pion-nucleon and nucleon-nucleon interaction on the basis of the fact that nuclear forces in the nucleon-nucleon system at low energies are mainly determined by the one-pion exchange mechanism. By making use of the recommended proton-proton low-energy scattering parameters, we obtain the following value for the charged pion-nucleon coupling constant g$_{\\pi ^{\\pm }}^{2}/4\\pi =14.55(13)$. Calculated value of this quantity is in excellent agreement with the experimental result g$_{\\pi ^{\\pm }}^{2}/4\\pi =14.52(26)$ of the Uppsala Neutron Research Group. At the same time, the obtained value of the charged pion-nucleon coupling constant differs markedly from the value of the neutral pion-nucleon coupling constant g$_{\\pi ^{0}}^{2}/4\\pi =13.55(13)$. Thus, our results show considerable charge splitting of the pion-nucleon coupling constant.
Measurement of the Electron Structure Function at LEP energies
Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, U; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W-D; Arnoud, Y; Ask, S; Asman, B; Augustin, J E; Augustinus, A; Baillon, P; Ballestrero, A; Bambade, P; Barbier, R; Bardin, D; Barker, G J; Baroncelli, A; Battaglia, M; Baubillier, M; Becks, K-H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N; Benvenuti, A; Berat, C; Berggren, M; Bertrand, D; Besancon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Bruckman, P; Brunet, J M; Buschbeck, B; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F; Chapkin, M; Charpentier, Ph; Checchia, P; Chierici, R; Chliapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D; Cuevas, J; D'Hondt, J; da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; De Boer, W; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; de Paula, L; Di Ciaccio, L; Di Simone, A; Doroba, K; Drees, J; Eigen, G; Ekelof, T; Ellert, M; Elsing, M; Espirito Santo, M C; Fanourakis, G; Fassouliotis, D; Feindt, M; Fernandez, J; Ferrer, A; Ferro, F; Flagmeyer, U; Foeth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J; Gandelman, M; Garcia, C; Gavillet, Ph; Gazis, E; Gokieli, R; Golob, B; Gomez-Ceballos, G; Goncalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Hoffman, J; Holmgren, S-O; Holt, P J; Houlden, M A; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Katsoufis, E; Kernel, G; Kersevan, B P; Kerzel, U; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kouznetsov, O; Krumstein, Z; Kucharczyk, M; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; Lopez, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Marechal, B; Margoni, M; Marin, J-C; Mariotti, C; Markou, A; Martinez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; Mc Nulty, R; Meroni, C; Migliore, E; Mitaroff, W; Mjoernmark, U; Moa, T; Moch, M; Moenig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Mueller, U; Muenich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, G; Myklebust, T; Nassiakou, M; Navarria, F; Nawrocki, K; Nemecek, S; Nicolaidou, R; Nikolenko, M; Oblakowska-Mucha, A; Obraztsov, V; Olshevski, A; Onofre, A; Orava, R; Osterberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, Th D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Pozdniakov, V; Pukhaeva, N; Pullia, A; Radojicic, D; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P; Richard, F; Ridky, J; Rivero, M; Rodriguez, D; Romero, A; Ronchese, P; Roudeau, P; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovsky, A; Salmi, L; Salt, J; Sander, C; Savoy-Navarro, A; Schwickerath, U; Sekulin, R; Siebel, M; Sisakian, A; Slominski, W; Smadja, G; Smirnova, O; Sokolov, A; Sopczak, A; Sosnowski, R; Spassov, T; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Szwed, J; Tabarelli, T; Tegenfeldt, F; Timmermans, J; Tkatchev, L; Tobin, M; Todorovova, S; Tome, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; Van Dam, P; Van Eldik, J; van Remortel, N; Van Vulpen, I; Vegni, G; Veloso, F; Venus, W; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O; Zalewska, A; Zalewski, P; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zintchenko, A; Zupan, M
2010-01-01
The hadronic part of the Electron Structure Function (ESF) has been measured for the first time, using e+e- data collected by the DELPHI experiment at LEP, at centre-of-mass energies sqrt(s) = 91.2-209.5 GeV. The data analysis is simpler than that of the measurement of the photon structure function. The ESF data are compared to predictions of phenomenological models based on the photon structure function. It is shown that the quasi-real photon virtuality contribution is significant. The presented data can serve as a cross-check of the photon structure function analyses and help in refining existing parametrizations.
Institute of Scientific and Technical Information of China (English)
N. Ghahramany; G.R. Boroun
2003-01-01
A calculation of the proton structure function F2(x,Q2) is reported with an approximation method that relates the reduced cross section derivative and the F2(x, Q2) scaling violation at low x by using quadratic form for the structure function. This quadratic form approximation method can be used to determine the structure function F2 (x, Q2)from the HERA reduced cross section data taken at low x. This new approach can determine the structure functions F2(x,Q2) with reasonable precision even for low x values which have not been investigated. We observe that the Q2 dependence is quadratic over the full kinematic covered range. To test the validity of our new determined structure functions, wefind the gluon distribution function in the leading order approximation with our new calculation for the structure functions and compare them with the QCD parton distribution functions.
Institute of Scientific and Technical Information of China (English)
N.Ghahramany; G.R.Boroun
2003-01-01
A calculation of the proton structure function F2(x,Q2) is reported with an approximation method that relates the reduced cross section derivative and the F2(x, Q2) scaling violation at low x by using quadratic form for the structure function. This quadratic form approximation method can be used to determine the structure function F2 (x, Q2) from the HERA reduced cross section data taken at low x. This new approach can determine the structure functions F2(x,Q2) with reasonable precision even for low x values which have not been investigated. We observe that the Q2 dependence is quadratic over the full kinematic covered range. To test the validity of our new determined structure functions, we find the gluon distribution function in the leading order approximation with our new calculation for the structure functions and compare them with the QCD parton distribution functions.
Structure and function of yeast alcohol dehydrogenase
Directory of Open Access Journals (Sweden)
VLADIMIR LESKOVAC
2000-04-01
Full Text Available 1. Introduction 2. Isoenzymes of YADH 3. Substrate specificity 4. Kinetic mechanism 5. Primary structure 6. The active site 7. Mutations in the yeast enzyme 8. Chemical mechanism 9. Binding of coenzymes 10. Hydride transfer
Structure and function of yeast alcohol dehydrogenase
VLADIMIR LESKOVAC; SVETLANA TRIVIC
2000-01-01
1. Introduction 2. Isoenzymes of YADH 3. Substrate specificity 4. Kinetic mechanism 5. Primary structure 6. The active site 7. Mutations in the yeast enzyme 8. Chemical mechanism 9. Binding of coenzymes 10. Hydride transfer
Relativistic density functional for nuclear structure
2016-01-01
This book aims to provide a detailed introduction to the state-of-the-art covariant density functional theory, which follows the Lorentz invariance from the very beginning and is able to describe nuclear many-body quantum systems microscopically and self-consistently. Covariant density functional theory was introduced in nuclear physics in the 1970s and has since been developed and used to describe the diversity of nuclear properties and phenomena with great success. In order to provide an advanced and updated textbook of covariant density functional theory for graduate students and nuclear physics researchers, this book summarizes the enormous amount of material that has accumulated in the field of covariant density functional theory over the last few decades as well as the latest developments in this area. Moreover, the book contains enough details for readers to follow the formalism and theoretical results, and provides exhaustive references to explore the research literature.
$\\psi^'$ production in Pb-Pb collisions at 158 GeV/nucleon
Alessandro, B; Arnaldi, R; Atayan, M; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Castor, J; Chaurand, B; Cheynis, B; Chiavassa, E; Cicalò, C; Comets, M P; Constantinescu, S; Cortese, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Fargeix, J; Force, P; Gallio, M; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Idzik, M; Jouan, D; Karavicheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; MacCormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scomparin, E; Serci, S; Shahoyan, R; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, E; Villatte, L; Willis, N
2007-01-01
\\psi^' production is studied in Pb-Pb collisions at 158 GeV/c per nucleon incident momentum. Absolute cross-sections are measured and production rates are investigated as a function of the centrality of the collision. The results are compared with those obtained for lighter colliding systems and also for the J/\\psi meson produced under identical conditions.
From Extraction of Nucleon Resonances to LQCD
Lee, T -S H; Kamano, Hiroyuki
2016-01-01
The intrinsic difficulties in extracting the hadron resonances from reaction data are illustrated by using several exactly soluble $\\pi\\pi$ scattering models. The finite-volume Hamiltonian method is applied to predict spectra using two meson-exchange Hamiltonians of $\\pi N$ reactions. Within a three-channel model with $\\pi N$, $\\pi\\Delta$ and $\\sigma N$ channels, we show the advantage of the finite-volume Hamiltonian method over the approach using the L\\"uscher formula to test Lattice QCD calculations aimed at predicting nucleon resonances. We discuss the necessary steps for using the ANL-Osaka eight-channel Hamiltonian to predict the spectra for testing the LQCD calculations for determining the excited nucleon states up to invariant mass $W= 2 $ GeV.
Sammarruca, Francesca
2013-01-01
After reviewing our microscopic approach to nuclear and neutron-rich matter, we focus on how nucleon-nucleon scattering is impacted by the presence of a dense hadronic medium, with special emphasis on the case where neutron and proton densities are different. We discuss in detail medium and isospin asymmetry effects on the total elastic cross section and the mean free path of a neutron or a proton in isospin-asymmetric nuclear matter. We point out that in-medium cross sections play an important role in heavy-ion simulations aimed at extracting constraints on the symmetry potential. We argue that medium and isospin dependence of microscopic cross sections are the results of a complex balance among various effects, and cannot be simulated with a simple phenomenological model.