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1.
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
2.
3.
D. Merten U. Löring K. Kretzschmar B. Metsch H.-R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2002,14(4):477-489
We compute electroweak form factors of the nucleon and photon transition form factors of non-strange baryon resonances up
to the third resonance region in a model with instanton-induced interaction. The calculation is based on the Bethe-Salpeter
equation for three light constituent quarks and is fully relativistic (U. L?ring et al., Eur. Phys. J. A 10, 309 (2001)). Static nucleon properties and photon resonance couplings are in good agreement with experiment and the Q2 behaviour of the experimentally known form factors up to large momentum transfer is accounted for.
Received: 4 April 2002 / Accepted: 2 May 2002 相似文献
4.
Bo-Wen Xiao Xin Qian Bo-Qiang Ma 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):523-527
The electromagnetic form factor of the kaon meson is calculated in the light-cone formalism of the relativistic constituent
quark model. The calculated K+ form factor is consistent with almost all of the available experimental data at low-energy scale, while other properties
of the kaon could also be interrelated in this representation with reasonable parameters. Predictions of the form factors
for the charged and neutral kaons at a higher-energy scale are also given, and we find the non-zero K0 form factor at Q
2≠ 0 due to the mass difference between the strange and down quarks inside K0.
Received: 21 June 2002 / Accepted: 29 July 2002 / Published online: 3 December 2002
RID="a"
ID="a"e-mail: mabq@phy.pku.edu.cn
Communicated by A. Sch?fer 相似文献
5.
N.D. Lai M. Brunel F. Bretenaker O. Emile 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):403-410
We study theoretically and experimentally different methods to control the pulses emitted by solid-state lasers passively
Q-switched by a saturable absorber. We explore one- and two-axis laser schemes allowing to control the pulse duration, which
is ruled by the saturation powers of the transitions in the absorber and in the gain medium. In one-axis lasers, it is shown
that the adjustment of the pump and laser beam sizes in the active medium and in the absorber provides an efficient means
to control the pulse temporal shape and duration. Furthermore, a two-axis laser cavity supporting so-called forked-eigenstate
operation permits to freely adjust the parts of the mode power which circulate in the gain medium and in the absorber. In
this case, a lengthening of the pulse duration up to 500 ns is obtained with an increase of the average output power. The
theoretical results obtained by using rate equations adapted to each cavity geometry are in close agreement with experiments
performed on a diode-pumped Nd3+:YAG laser Q-switched by a Cr4+:YAG saturable absorber. The relevance of the different techniques to control the pulse durations in the framework of potential
applications is discussed.
Received 3 December 2001 相似文献
6.
C. Herberg M. Ostrick H.G. Andresen J.R.M. Annand K. Aulenbacher J. Becker P. Drescher D. Eyl A. Frey P. Grabmayr S.J. Hall P. Hartmann T. Hehl W. Heil J. Hoffmann D. Ireland J.D. Kellie F. Klein K. Livingston Ch. Nachtigall A. Natter E.W. Otten R.O. Owens E. Reichert D. Rohe H. Schmieden R. Sprengard M. Steigerwald K.-H. Steffens Th. Walcher R. Watson 《The European Physical Journal A - Hadrons and Nuclei》1999,5(2):131-135
The electric form factor of the neutron G
E,n has been determined at the Mainz Microtron MAMI at the low momentum transfer Q
2= 0.15 (GeV/c)2 in a measurement of the recoil polarisation ratio P
x/Pz in the quasifree reaction D(e,e′n)p. At this Q
2 the influence of the nuclear binding is strong. A purely kinematical model is used to get some insight into the effect of
the initial Fermi momentum distribution of the neutron. The influence of the final state interaction is determined quantitatively
by a model of Arenh?vel et al.. After the corresponding corrections a value of G
E,n(0.15 (GeV/c)2) = 0.0481±0.0065stat±0.0053syst is obtained.
Received: 12 April 1999 相似文献
7.
8.
Y. Toh T. Czosnyka M. Oshima T. Hayakawa H. Kusakari M. Sugawara Y. Hatsukawa J. Katakura N. Shinohara M. Matsuda 《The European Physical Journal A - Hadrons and Nuclei》2000,9(3):353-356
74Ge beam was Coulomb-excited on a natPb target. Ten E2 matrix elements including diagonal matrix elements for 5 low-lying states have been determined using the least-squares search
code GOSIA. The expectation values of the rotational invariants 〈Q
2〉 and 〈cos3δ〉 show the small and triaxial deformation of the two lowest members of the ground-state band , while the 02
+ and 22
+ states are found to be almost spherical.
Received: 31 August 2000 / Accepted: 4 December 2000 相似文献
9.
W. Urban J.A. Pinston T. Rzaca-Urban A. Złomaniec G. Simpson J.L. Durell W.R. Phillips A.G. Smith B.J. Varley I. Ahmad N. Schulz 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):11-15
A new band, populated by the spontaneous fission of 248Cm and studied by means of prompt γ-ray spectroscopy using the EUROGAM2 array, was observed in 99Zr. The 1038.8 keV band head with a half-life T
1/2 = 54(10) ns is interpreted as a K-isomer, corresponding to the 9/2[404] neutron-hole excitation. It is the first observation of this orbital in the mass A ∼ 100 region. The quadrupole moment, Q
0 = 3.9(3) eb deduced for the new band indicates a large deformation of β = 0.41, which is produced by a specific shape-coexistence
mechanism, known in other regions and now found in the A ∼ 100 nuclei.
Received: 11 September 2002 / Accepted: 31 October 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: urban@fuw.edu.pl
Communicated by D. Schwalm 相似文献
10.
Yu-bing Dong 《The European Physical Journal A - Hadrons and Nuclei》1998,1(3):347-354
In this paper, the spin-dependent structure functions of nucleon g
1, and photoabsorption cross sections σ1/2, σ3/2 and σT in the resonance region are estimated based on the constituent quark model and the properties of the five phenomenological
Breit-Wigner resonances P
33(1232), S
11(1535), D
13(1520), P
11(1440), and F
15(1680). Our results are compared to the recent E143 data of the polarized structure functions g
1(W
2, Q
2) at points Q
2=0.5 GeV2 and Q
2=1.2 GeV2 and the data of the total inclusive photoabsorption cross sections.
Received: 7 October 1997 相似文献
11.
Y. Fujita H. Fujita T. Adachi G.P.A. Berg E. Caurier H. Fujimura K. Hara K. Hatanaka Z. Janas J. Kamiya T. Kawabata K. Langanke G. Martınez-Pinedo T. Noro E. Roeckl Y. Shimbara T. Shinada S.Y. van der Werf M. Yoshifuku M. Yosoi R.G.T. Zegers 《The European Physical Journal A - Hadrons and Nuclei》2002,13(4):411-418
Under the assumption that isospin is a good quantum number, symmetry is expected for the transitions from the ground states
of T = 1, T
z = ±1 nuclei to the common excited states of the T
z = 0 nucleus situated between the two nuclei. The symmetry can be studied by comparing the strengths of Gamow-Teller (GT)
transitions obtained from a (p, n)-type charge-exchange reaction on a target nucleus with T
z = 1 with those from the β-decay of the T
z = - 1 nucleus. The A = 58 system is the heaviest for which such a comparison is possible. As a part of the symmetry study, we measured the GT
transitions from 58Ni (T
z = 1) to 58Cu (T
z = 0) by using the zero-degree (3
He, t) reaction at 150 MeV/nucleon. With the achieved resolution of 50 keV, many hitherto unresolved GT states have been identified.
The GT transition strengths were obtained for states up to 8 MeV excitation, i.e., near to the Q window limitation ( Q
EC = 9.37 MeV) of the β-decay from 58Zn (T
z = - 1) to 58Cu. The strength distribution is compared with that from shell-model calculations.
Received: 24 November 2001 / Accepted: 30 January 2002 相似文献
12.
Th. Pospischil P. Bartsch D. Baumann R. Böhm K. Bohinc M. Ding S. Derber M.O. Distler D. Elsner I. Ewald J. Friedrich J.M. Friedrich S. Grözinger S. Hedicke P. Jennewein J. Jourdan M. Kahrau F. Klein K.W. Krygier J. Lac A. Liesenfeld S. Malov J. McIntyre H. Merkel P. Merle U. Müller R. Neuhausen M. Potokar R.D. Ransome D. Rohe G. Rosner J. Sanner H. Schmieden M. Seimetz S. Širca I. Sick O. Strähle A. Süle A. Wagner Th. Walcher M. Weis 《The European Physical Journal A - Hadrons and Nuclei》2001,12(1):125-127
The polarization transfer from longitudinally polarized electrons to protons in the elastic scattering p(
e, e'
p) has been measured around Q2 = 0.4 (GeV/c)2 with the three-spectrometer facility at the Mainz microtron MAMI. From this polarization transfer the ratio G
Ep/(G
Mp/μp) has been determined. The ratio is found to be slightly less than unity in agreement with recent results from other laboratories
and from the Rosenbluth separation of cross-sections measured with unpolarized electrons.
Received: 26 July 2001 / Accepted: 25 September 2001 相似文献
13.
L. Jenkovszky V.K. Magas E. Predazzi 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):361-367
By using the concept of duality between direct channel resonances and Regge exchanges we relate the small- and large-x behavior of the structure functions. We show that even a single resonance exhibits Bjorken scaling at large Q2.
Received: 30 October 2001 / Accepted: 16 November 2001 相似文献
14.
W. Melnitchouk 《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):223-234
We explore the relationship between exclusive and inclusive electromagnetic scattering from the pion, focusing on the transition
region at intermediate Q2. Combining Drell-Yan data on the leading twist quark distribution in the pion with a model for the resonance region at large
x, we calculate QCD moments of the pion structure function over a range of Q2, and quantify the role of higher twist corrections. Using a parameterization of the pion elastic form factor and phenomenological
models for the π↦ρ transition form factor, we further test the extent to which local duality may be valid for the pion.
Received: 10 February 2003 / Accepted: 12 March 2003 / Published online: 27 May 2003 相似文献
15.
We analyse the low x, low Q
2 polarised photoabsorption data from SLAC and use this data to make a first estimate of the high-energy part of the Drell-Hearn-Gerasimov
sum-rule. The present status of spin dependent Regge theory is discussed.
Received: 23 October 1998 相似文献
16.
M. Sugawara Y. Toh T. Czosnyka M. Oshima T. Hayakawa H. Kusakari Y. Hatsukawa J. Katakura N. Shinohara M. Matsuda T. Morikawa A. Seki F. Sakata 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):409-414
Electromagnetic properties of the low-lying states in a 70Ge nucleus were studied through the multiple Coulomb excitation of a 70Ge beam with a natPb target. Relative γ-ray intensities were measured as a function of emission angle relative to the scattered projectile.
Sixteen E2 matrix elements, including diagonal ones, for 6 low-lying states have been determined using the least-squares search code
GOSIA. The expectation values 〈Q
2〉 of 01
+ and 02
+ states in 70Ge are compared with those in 72, 74, 76Ge. Simple mixing calculations indicate that the 02
+ states in 70Ge and 72Se can be treated as deformed intruder states. It is shown that the deformed intruder becomes the ground state in 74Kr. These interpretations of the 02
+ states in this region are compared with the potential-energy surface calculations by the Nilsson-Strutinsky model, which
allow to interpret the experimental results in a qualitative way from the theoretical point of view.
Received: 2 September 2002 / Accepted: 5 November 2002 / Published online: 25 February 2003
RID="a"
ID="a"e-mail: sugawara@pf.it-chiba.ac.jp
Communicated by D. Schwalm 相似文献
17.
Y.P. Gangrsky D.V. Karaivanov K.P. Marinova B.N. Markov L.M. Melnikova G.V. Mishinsky S.G. Zemlyanoi V.I. Zhemenik 《The European Physical Journal A - Hadrons and Nuclei》1998,3(4):313-318
The hyperfine structure of the D2 optical line in 22Na and 23Na has been investigated using high resolution laser spectroscopy of a well-collimated atomic beam. The hyperfine splitting
constants A and B for the excited 3p 2P3/2 level for both investigated sodium isotopes have been obtained. They are as follows: A(22) = 7.31(4) MHz, B(22) = 4.71(28)
MHz, A(23) = 18.572(24) MHz, B(23) = 2.723(55) MHz. With this data, using the high precision MCHF calculations for the electric
field gradient at the nucleus, the electric quadrupole moment of 22Na has been deduced: Qs(22) =+0.185(11) b. The sign of Qs(22), determined for the first time, indicates a prolate nuclear deformation. A precise value of the isotope shift 22,23Na in the D2 line has also been obtained.
Received: 26 February 1998 / Revised version: 25 June 1998 相似文献
18.
19.
M. Koll R. Ricken D. Merten B.C. Metsch H.R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):73-94
We present new results of a relativistic quark model based on the Bethe-Salpeter equation in its instantaneous approximation.
Assuming a linearly rising confinement potential with an appropriate spinorial structure in Dirac space and adopting a residual
interaction based on instanton effects, we can compute masses of the light mesons up to highest observed angular momenta with
a natural solution of the U
A(1) problem. The calculated ground states masses and the radial excitations describe the experimental results well. In this
paper, we will also discuss our results concerning numerous meson decay properties. For processes like π+/K
+↦e
+υeγ and 0-↦γγ at various photon virtualities, we find a good agreement with experimental data. We will also comment on the form factors
of the K
?3 decay and on the decay constants of the π, K and η mesons. For the sake of completeness, we will furthermore present the electromagnetic form factors of the charged π
and K mesons as well as a comparison of the radiative meson decay widths with the most recent experimental data.
Received: 28 August 2000 / Accepted: 12 September 2000 相似文献
20.
We calculate target fragmentation in pp→nX and γp→nX reactions in the meson cloud picture of the nucleon. The pp→nX reaction is used to fix the pnπ+ form factor for three different models. We take into account the possible destruction of the residual neutron by the projectile.
Using the form factor from the hadronic reaction we calculate photoproduction and small x
Bj electroproduction of forward neutrons at HERA. Here the qˉq dipoles in the photon can rescatter on the residual neutron. In photoproduction we observe slightly less absorption than
in the hadronic reaction. For deep inelastic events (Q
2 > 10 GeV2) screening is weaker but still present at large Q
2. The signature for this absorptive rescattering is a shift of the dσ/dEn distribution to higher neutron energies for photofragmentation.
Received: 12 June 1999 / Revised version: 12 October 1999 相似文献