排序方式: 共有34条查询结果,搜索用时 15 毫秒
1.
A forward dispersion calculation is implemented for the spin polarizabilities γ1,,γ4 of the proton and the neutron. These polarizabilities are related to the spin structure of the nucleon at low energies and are structure-constants of the Compton scattering amplitude at
. 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. 相似文献
2.
M. Guidal 《Progress in Particle and Nuclear Physics》2008,61(1):89-105
We give a pedagogical introduction to the field of Generalized Parton Distributions and review shortly the experimental situation and perspective for Deep Virtual Compton Scattering. 相似文献
3.
We calculate the next-to-leading order perturbative corrections to the SVZ sum rules for the coupling fN, the nucleon leading twist wave function at the origin. The results are compared to the established Ioffe sum rules and also to lattice QCD simulations. 相似文献
4.
5.
6.
Yanyun Chu Zhongzhou Ren Chang Xu 《The European Physical Journal A - Hadrons and Nuclei》2008,37(3):361-366
Using a three-body model and realistic two-body potentials, we investigate the properties of the nuclei 18Ne and 28S near the proton dripline. We figure out the two-proton separation energies, occupation of the valence protons, root-mean-square
radii of matter and the valence protons. Besides, the spatial correlation densities are displayed to reflect the correlation
between the two valence protons. The first excited 0+ state of 18Ne is most likely to be a halo state according to our calculation. Turning off the Coulomb interactions among the three-body
systems, we get the two-neutron separation energies and configuration of the valence neutrons of their corresponding mirror
nuclei. The results indicate that the three-body model is proper to describe some proton-rich nuclei and can be used to deduce
reliable information. 相似文献
7.
C.D. Roberts 《Progress in Particle and Nuclear Physics》2008,61(1):50-65
An overview of the theory and phenomenology of hadrons and QCD is provided from a Dyson-Schwinger equation viewpoint. Following a discussion of the definition and realization of light-quark confinement, the nonperturbative nature of the running mass in QCD and inferences from the gap equation relating to the radius of convergence for expansions of observables in the current-quark mass are described. Some exact results for pseudoscalar mesons are also highlighted, with details relating to the UA(1) problem, and calculated masses of the lightest J=0,1 states are discussed. Studies of nucleon properties are recapitulated upon and illustrated: through a comparison of the ln-weighted ratios of Pauli and Dirac form factors for the neutron and proton; and a perspective on the contribution of quark orbital angular momentum to the spin of a nucleon at rest. Comments on prospects for the future of the study of quarks in hadrons and nuclei round out the contribution. 相似文献
8.
A simple statistical model in terms of light-front kinematic variables is used to explain the nuclear EMC effect in the range x[0.2,0.7], which was constructed by us previously to calculate the parton distribution functions (PDFs) of the nucleon. Here, we treat the temperature T as a parameter of the atomic number A, and get reasonable results in agreement with the experimental data. Our results show that the larger A, the lower T thus the bigger volume V, and these features are consistent with other models. Moreover, we give the predictions of the quark distribution ratios, i.e., qA(x)/qD(x), , and sA(x)/sD(x), and also the gluon ratio gA(x)/gD(x) for iron as an example. The predictions are different from those by other models, thus experiments aiming at measuring the parton ratios of anti-quarks, strange quarks, and gluons can provide a discrimination of different models. 相似文献
9.
The nucleon form factors of the energy–momentum tensor are studied in nuclear medium in the framework of the in-medium modified Skyrme model. We obtain a negative D -term, in agreement with results from other approaches, and find that medium effects make the value of d1 more negative. 相似文献
10.
The nucleon exchange process between two nuclei in close proximity and its application to an explanation of fragment mass
and charge distributions in fission and in heavy ion deep inelastic collisions are reviewed. An analysis of the measured correlations
between the energy loss from relative motion and the fragment mass and charge variances in the heavy ion deep inelastic collisions
is presented. The recent data on fragment mass and charge variances as a function of the fragment kinetic energy in thermal
neutron induced fission of235U, lends added support to the hypothesis that the nucleon transport process plays a similar role both in fission and in heavy
ion deep inelastic collisions. 相似文献