共查询到20条相似文献,搜索用时 31 毫秒
1.
M.P. Rekalo E. Tomasi-Gustafsson 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):563-567
We discuss the applicability of pQCD to the elastic scattering of electrons on protons and deuterons. We analyze the Q2-dependence of the reduced deuteron form factor, taking into account the recent data on the electric proton form factor and
we find that the value of the QCD-scale parameter Λ differs essentially from the value Λ = 0.1 GeV, previously found using
the dipole parametrization of the electromagnetic nucleon form factors GE and GM. Moreover, the predicted scaling behavior of the reduced deuteron form factor cannot be recovered in the Dirac and Pauli
representations for the nucleon electromagnetic form factors.
Received: 14 October 2002 / Accepted: 12 November 2002 / Published online: 11 March 2003
RID="a"
ID="a"Permanent address: National Science Center KFTI, 310108 Kharkov, Ukraine.
RID="b"
ID="b"e-mail: etomasi@cea.fr
Communicated by V.V. Anisovich 相似文献
2.
U.T. Yakhshiev U.-G. Meißner A. Wirzba 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):569-574
We investigate the possible modifications of the nucleons' electromagnetic form factors in the framework of a modified Skyrme
model allowing for nucleon deformation and using realistic nuclear mass distributions. We show that such effects are small
in light nuclei
Received: 19 November 2002 / Accepted: 3 December 2002 / Published online: 18 March 2003
RID="a"
ID="a"Address after January 1st, 2003: Helmholtz Institut für Strahlen- und Kernphysik (Theorie), Universit?t Bonn, Nu?allee
14-16, D-53115 Bonn, Germany; e-mail: meissner@itkp.uni-bonn.de
RID="b"
ID="b"Present address: Helmholtz Institut für Strahlen- und Kernphysik (Theorie), Universit?t Bonn, D-53115 Bonn, Germany.
Communicated by V. Vento 相似文献
3.
K. Kossert M. Camen F. Wissmann J. Ahrens J.R.M. Annand H.-J. Arends R. Beck G. Caselotti P. Grabmayr O. Jahn P. Jennewein M.I. Levchuk A.I. L'vov J.C. McGeorge A. Natter V. Olmos de León V.A. Petrun'kin G. Rosner M. Schumacher B. Seitz F. Smend A. Thomas W. Weihofen F. Zapadtka 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):259-273
Differential cross-sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been
measured using the Glasgow/Mainz photon tagging spectrometer at the Mainz MAMI accelerator together with the Mainz [48]cm
;SPMOslash; × [64]cm NaI(Tl) photon detector and the G?ttingen SENECA recoil detector. The data cover photon energies ranging from [200]MeV
to [400]MeV at θLAB
γ = 136.2°. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron
detection efficiency of the SENECA detector was measured via the reaction p(γ,π+
n). The “free” proton Compton scattering cross-sections extracted from the bound proton data are in reasonable agreement with
those for the free proton which gives confidence in the method to extract the differential cross-section for free scattering
from quasi-free data. Differential cross-sections on the free neutron have been extracted and the difference of the electromagnetic
polarizabilities of the neutron has been determined to be αn - βn = 9.8±3.6(stat)+2.1
-1.1(syst)±2.2(model) in units of [10-4]fm
3. In combination with the polarizability sum αn + βn = 15.2±0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, αn = 12.5±1.8(stat)+1.1
-0.6(syst)±1.1(model) and βn = 2.7±1.8(stat)+0.6
-1.1(syst)±1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be γ(n)
π = (58.6±4.0)×10-4
fm
4.
Received: 21 August 2002 / Accepted: 16 October 2002 / Published online: 11 February 2003
RID="a"
ID="a"Part of the Doctoral Thesis.
RID="b"
ID="b"Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig.
RID="a"
ID="a"Part of the Doctoral Thesis.
RID="b"
ID="b"Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig.
RID="c"
ID="c"Part of the Habilitation Thesis.
RID="d"
ID="d"e-mail: schumacher@physik2.uni-goettingen.de
Communicated by Th. Walcher 相似文献
4.
M. Oettel R. Alkofer L. von Smekal 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):553-566
In the covariant quark-diquark model the effective Bethe-Salpeter (BS) equations for the nucleon and the Δ are solved including
scalar and axial vector diquark correlations. Their quark substructure is effectively taken into account in both, the interaction kernel of the BS
equations and the currents employed to calculate nucleon observables. Electromagnetic current conservation is maintained.
The electric form factors of proton and neutron match the data. Their magnetic moments improve considerably by including axial
vector diquarks and photon induced scalar-axial vector transitions. The isoscalar magnetic moment can be reproduced, the isovector
contribution is about 15% too small. The ratio μG
E/G
M and the axial and strong couplings g
A, g
NN, provide an upper bound on the relative importance of axial vector diquarks confirming that scalar diquarks nevertheless
describe the dominant 2-quark correlations inside nucleons.
Received: 3 July 2000 / Accepted: 15 August 2000 相似文献
5.
A. Borah S. Ghosh S. Nandy 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):221-225
The novel inelastic collision properties of two-soliton interaction for an n-component coupled higher order nonlinear Schr?dinger equation are studied. Some interesting features of three soliton interactions,
related to the integrability of the n-component coupled higher order nonlinear Schr?dinger equation are also discussed.
Received 17 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: abhijit@iitg.ernet.in
RID="b"
ID="b"e-mail: sasanka@iitg.ernet.in
RID="c"
ID="c"e-mail: sudipta@iitg.ernet.in 相似文献
6.
We extract the neutron charge form factor G
n
E(Q
2) from the charge form factor of deuteron G
d
C(Q
2) obtained from T
20(Q
2) data at 0≤Q
2≤ 1.717 (GeV/c)2. The extraction is based on the relativistic impulse approximation in the instant form of the relativistic Hamiltonian dynamics.
Our results (12 new points) are compatible with existing values of the neutron charge form factor of other authors. We propose
a fit for the whole set (36 points) taking into account the data for the slope of the form factor at Q
2 = 0.
Received: 26 July 2002 / Accepted: 18 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: krutov@ssu.samara.ru
RID="b"
ID="b"e-mail: troitsky@theory.sinp.msu.ru
Communicated by V.V. Anisovich 相似文献
7.
Hong-yi Fan J. Chen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):437-442
Based on the newly constructed Einstein, Podolsky and Rosen (EPR) entangled state representation we introduce macroscopic
classical functions associated with atomic coherent state τ with angular momentum value j. These functions are proportional to the ordinary one-variable Hermite polynomials of order 2j. The corresponding Wigner quasiprobability function for τ in phase space is also derived which turns out to be a two-variable Hermite polynomial H
2j, 2j. In so doing, a new classical-quantum correspondence scheme for angular momentum system is established.
Received 7 August 2002 / Received in final form 14 December 2002 Published online 24 April 2003
RID="a"
ID="a"Work supported by the National Natural Science Foundation of China under grant 10175057.
RID="b"
ID="b"e-mail: fhym@sjtu.edu.en 相似文献
8.
9.
R. Lucas M.-G. Porquet Ts. Venkova I. Deloncle M. Houry Ch. Theisen A. Astier A. Bauchet S. Lalkovski G. Barreau N. Buforn T.P. Doan L. Donadille O. Dorvaux J. Durell Th. Ethvignot B.P.J. Gall D. Grimwood W. Korten Y. Le Coz M. Meyer A. Minkova A. Prévost N. Redon A. Roach N. Schulz A.G. Smith O. Stézowski B.J. Varley 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):315-323
The 115, 117, 119, 121In nuclei have been produced as fission fragments in three reactions induced by heavy ions: 12C + 238U at 90MeV bombarding energy, 18O + 208Pb reaction at 85MeV, and 31P + 176Yb at 152MeV. Their level schemes have been built from gamma-rays detected using the EUROBALL III and IV arrays. High-spin
states of 117, 119, 121In nuclei have been identified for the first time. Moreover, isomeric states lying around 2.5MeV have been established in
119, 121In from the delayed coincidences between the fission fragment detector SAPhIR and the gamma array. Most of the observed states
can be described by coupling a proton g
9/2 hole to a Sn core, while the intruder band based on an orbital from the π[g
7/2/d
5/2] sub-shells behaves as the ground-state band of neighbouring Cd isotopes.
Received: 24 May 2002 / Accepted: 11 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: porquet@csnsm.in2p3.fr
RID="b"
ID="b"Present address: CEA-DIF, DAM/DCRE/SDE/LDN, 91680 Bruyères-le-Chatel, France.
RID="c"
ID="c"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France.
RID="d"
ID="d"Present address: CEA/Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette Cedex, France.
Communicated by D. Schwalm 相似文献
10.
R.-D. Herzberg N. Amzal J.E. Bastin F. Becker P.M.T. Brew P.A. Butler A.J.C. Chewter J.F.C. Cocks O. Dorvaux K. Eskola J. Gerl P.T. Greenlees N.J. Hammond K. Hauschild K. Helariutta F. Heßberger M. Houry A. Hürstel R.D. Humphreys G.D. Jones P.M. Jones R. Julin S. Juutinen H. Kankaanpää H. Kettunen T.L. Khoo W. Korten P. Kuusiniemi Y. Le Coz M. Leino A.P. Leppänen C.J. Lister R. Lucas M. Muikku P. Nieminen R.D. Page T. Page P. Rahkila P. Reiter Ch. Schlegel C. Scholey G. Sletten O. Stezowski Ch. Theisen W.H. Trzaska J. Uusitalo H.J. Wollersheim 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):205-208
In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei 253, 254No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator
RITU at the University of Jyv?skyl?. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations.
The implications for the ground-state configuration of 253No are discussed.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: rdh@ns.ph.liv.ac.uk
RID="b"
ID="b"Present address: GANIL, F-14021 Caen, France.
RID="c"
ID="c"Permanent address: IReS Strasbourg, IN2P3-CNRS, F-67037-Strasbourg, France.
RID="d"
ID="d"Present address: CEA/DIF DCRE/SDE/LDN F-91680 Bruyeres-le-Chatel.
RID="e"
ID="e"Present address: Daresbury Laboratory, Daresbury WA4 4AD, UK.
RID="f"
ID="f"Permanent address: IPN Lyon, IN2P3-CNRS, F-69037 Lyon, France. 相似文献
11.
M.-G. Porquet Ts. Venkova P. Petkov A. Bauchet I. Deloncle A. Astier N. Buforn J. Duprat B.J.P. Gall C. Gautherin E. Gueorguieva F. Hoellinger T. Kutsarova R. Lucas M. Meyer A. Minkova N. Redon N. Schulz H. Sergolle A. Wilson 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):463-470
The 106, 108Rh and 110, 112Ag nuclei have been produced as fission fragments following the fusion reaction 28Si + 176Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. The yrast high-spin states of these four odd-odd nuclei,
which are observed for the first time, consist of rotational bands in which the odd proton occupies the πg
9/2 subshell and the odd neutron the νh
11/2 subshell. Their behaviour as a function of spin values does not vary with the number of neutrons: as observed in the odd-N neighbouring nuclei, the motion of the odd neutron remains decoupled from the motion of the core, from N = 61 to N = 65. Moreover, the staggering observed in the yrast bands of odd-odd isotopes is strongly reduced as compared to the large
values displayed by the rotational bands built on the πg
9/2 subshell in the odd-A Rh and Ag isotopes. The results of particle-rotor calculations indicate that this reduction is related to a change of the
core deformation.
Received: 1 June 2001 / Accepted: 23 July 2002 / Published online: 10 December 2002
RID="a"
ID="a"e-mail: porquet@csnsm.in2p3.fr
RID="b"
ID="b"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France.
RID="c"
ID="c"Present address: NAC, Faure, ZA 7131, South Africa.
RID="d"
ID="d"Present address: Department of Nuclear Physics, ANU, Canberra ACT 0200, Australia.
Communicated by D. Schwalm 相似文献
12.
A. Hürstel M. Rejmund E. Bouchez P.T. Greenlees K. Hauschild S. Juutinen H. Kettunen W. Korten Y. Le Coz P. Nieminen Ch. Theisen A.N. Andreyev F. Becker T. Enqvist P.M. Jones R. Julin H. Kankaanpää A. Keenan P. Kuusiniemi M. Leino A.-P. Leppänen M. Muikku J. Pakarinen P. Rahkila J. Uusitalo 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):329-334
Prompt and delayed gamma-ray spectroscopy of very neutron-deficient bismuth isotopes 187, 189Bi has been performed using the Recoil Decay Tagging (RTD) method. The isomeric i
13/2 states have been identified and their lifetimes have been measured. The systematics of these long-lived M2 isomers has been extended to the proton-unbound isotopes. The general behaviour of single-proton states is discussed within
the systematics and interpreted within the shell-model framework.
Received: 2 May 2002 / Accepted: 3 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: wkorten@cea.fr
RID="b"
ID="b"Present address: GANIL, Caen, France.
RID="c"
ID="c"Present address: Radiation and Nuclear Safety Authority, P.O. Box 14, FIN-00881 Helsinki.
Communicated by D. Schwalm 相似文献
13.
J.C. Cao X.L. Lei 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):553-559
We have extended the balance equations to account for conduction-valence interband impact ionization (II) process induced
by an intense terahertz (THz) electromagnetic irradiation in semiconductors, and applied them to study the II effect on electron
transport and electron-hole pair generation-recombination rate in THz-driven InAs/AlSb heterojunctions (HJ). As many as needed
multiphoton channels are self-consistently taken into account for yielding a given accuracy. The time evolution of transport
state including THz-radiation-induced II process are monitored in details by an extensive time-dependent analysis. Two different
physical stages, the quasi-steady state and the complete steady-state, are clearly identified from the present calculations.
Intersubband electron transfer rate and net electron-hole generation rate are derived as functions of the THz radiation strength
E
ac for various radiation frequencies from f
ac = 0.42 to 6 THz at lattice temperatures T = 6 K. It's indicated that the THz radiation with a larger E
ac or a lower f
ac, has a stronger effect on electron transport and II process. Qualitative agreement is obtained between the calculated electron-hole
generation rate and the available experimental data for InAs/AlSb HJ's at T = 6 K.
Received 24 May 2002 / Received in final form 26 August 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: jccao8@hotmail.com 相似文献
14.
D. Pierroutsakou M. Di Toro F. Amorini V. Baran A. Boiano A. De Rosa A. D'Onofrio G. Inglima M. La Commara A. Ordine N. Pellegriti F. Rizzo V. Roca M. Romoli M. Sandoli M. Trotta S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):423-435
We report on the results obtained from the study of the 32S + 64Ni and 32S + 58Ni peripheral reactions at incident energies E
lab = 288 MeV and E
lab = 320 MeV, respectively. High-energy γ-rays were detected in an array of 8 seven-pack BaF2 clusters. Coincidence with complex fragments detected in 12 three-stage telescopes ensured the selection of peripheral reaction
events. All of the relevant reaction parameters were kept constant with the exception of the different initial dipole moment
caused by the different entrance channel charge asymmetry. While for quasi-elastic events no N/Z effect was observed in the differential γ-ray multiplicities of the two reactions, for deep-inelastic events a larger dipole
γ-ray emission occurs during the more N/Z asymmetric reaction. A theoretical interpretation based on a collective Bremsstrahlung analysis of the reaction dynamics
is presented.
Received: 26 September 2002 / Accepted: 13 November 2002 / Published online: 6 March 2003
RID="a"
ID="a"e-mail: pierroutsakou@na.infn.it
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Padova, Italy.
Communicated by C. Signorini 相似文献
15.
G. De Smedt C. Godrèche J.M. Luck 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(2):215-225
We consider a ferromagnetic Ising chain evolving under Kawasaki dynamics at zero temperature. We investigate the statistics
of the blocking time, as well as various characteristics of the metastable configurations reached by the system, including
the statistics of the final energy, the spin correlations, and the distribution of domain sizes. Results of extensive numerical
simulations are compared with analytical predictions made for the a priori ensemble of all blocked configurations with equal weights. Qualitative differences are found, e.g. in the domain sizes, which are found to be neither statistically independent nor exponentially distributed.
Received 24 October 2002 / Received in final form 13 January 2003 Published online 1st April 2003
RID="a"
ID="a"e-mail: luck@spht.saclay.cea.fr
RID="b"
ID="b"URA 2306 of CNRS 相似文献
16.
V.S. Gerdjikov G.G. Grahovski N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):243-248
The class of nonlinear evolution equations (NLEE) - gauge equivalent to the N-wave equations related to the simple Lie algebra are derived and analyzed. They are written in terms of (x, t) ∈ satisfying r = rank nonlinear constraints. The corresponding Lax pairs and the time evolution of the scattering data are found. The Zakharov-Shabat
dressing method is appropriately modified to construct their soliton solutions.
Received 20 October 2001 / Received in final form 30 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
17.
We study the quark mass expansion of the magnetic moments of the nucleon in a chiral effective field theory including nucleons,
pions and delta-resonances as explicit degrees of freedom. We point out that the usual power counting applied so far to this
problem misses important quark mass structures generated via an intermediate isovector M1 nucleon-delta transition. We propose a modified power counting and compare the resulting chiral extrapolation function to
available (quenched) lattice data. The extrapolation is found to work surprisingly well, given that the lattice data result
from rather large quark masses. Our calculation raises the hope that extrapolations of lattice data utilizing chiral effective
field theory might be applicable over a wider range in quark masses than previously thought, and we discuss some open questions
in this context. Furthermore, we observe that within the current lattice data uncertainties the extrapolations presented here
are consistent with the Padé fit ansatz introduced by the Adelaide group a few years ago.
Received: 23 April 2002 / Accepted: 18 July 2002 / Published online: 17 December 2002
RID="c"
ID="c"e-mail: themmert@physik.tu-muenchen.de
RID="d"
ID="d"e-mail: weise@ect.it
Communicated by A. Sch?fer 相似文献
18.
D. Bucurescu A. Gadea Ghe. Căta-Danil I. Căta-Danil M. Ivaşcu N. Mărginean C. Rusu L. Stroe C.A. Ur 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):469-474
High-spin states in the 97Tc nucleus have been studied by in-beam γ-ray spectroscopy with the reaction 82Se(19F,4nγ) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2. The observed
level scheme is compared with results of shell model calculations.
Received: 22 November 2002 / Accepted: 23 December 2002 / Published online: 18 March 2003
RID="a"
ID="a"e-mail: bucurescu@tandem.nipne.ro
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="c"
ID="c"Present address: Università di Padova, Padova, Italy.
Communicated by C. Signorini 相似文献
19.
M.P. Rekalo E. Tomasi-Gustafsson 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):575-581
The associative charm particles production in nucleon-nucleon collisions N + N↦Λc(Σc) + ˉD + N, is described in a general way and the spin and isospin structure of the corresponding matrix elements are derived. Using
an analogy with strange-particle (ΛK) production, the D-meson exchange model is considered in detail. Estimations of the energy behavior of the threshold cross-sections show a large
dependence on the form of the phenomenological hadron form factors and indicate that, at threshold, the cross-section is three
orders of magnitude smaller than for strange-particle production.
Received: 18 October 2002 / Accepted: 5 December 2002 / Published online: 18 March 2003
RID="a"
ID="a"Permanent address: National Science Center KFTI, 310108 Kharkov, Ukraine.
RID="b"
ID="b"e-mail: etomasi@cea.fr
Communicated by V.V. Anisovich 相似文献
20.
R.A. Radhi 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):387-392
Electron scattering Coulomb form factors for the single-particle quadrupole transitions in p-shell and sd-shell nuclei have been studied. Core polarization effects are included through a microscopic theory that includes excitations
from the core orbits up to higher orbits with 2ω excitations. The modified surface delta interaction is adopted as a residual
interaction. The results are discussed for the ( 1p
1/2
-1↦1p
3/2
-1) proton transition in 15N, ( 1d
5/2↦2s
1/2) neutron transition in 17O and ( 1d
3/2
-1↦2s
1/2
-1) proton transition in 39K. The inclusion of core polarization effects modifies the form factors markedly and describes the experimental data very
well in both the absolute strength and the momentum transfer dependence.
Received: 18 April 2002 / Accepted: 1 July 2002 / Published online: 6 March 2003
RID="a"
ID="a"e-mail: baguniv@uruklink.net
Communicated by A. Molinari 相似文献