相关论文: The Drell-Hearn-Gerasimov Sum-Rule in QCD
Two new sum rules are derived relating Dirac radii and anomalous magnetic moments of the considered strongly interacting fermions with the convergent integral over a difference of the total proton and neutron, as well as $He^3$ and $H^3$,…
The compatibility of the QCD sum rules and effective hadronic models predictions are examined. For this purpose we have considered the results for the nucleon self-energy in a dense hadronic environment provided by two independent QCD…
Our knowledge on the nucleon spin structure has greatly improved over the last twenty years or so, but still many fundamental questions remain unsolved. I will try to review some of the puzzling aspects of the origin of the nucleon spin. I…
Recently the \mu_{\Delta ^{++}} was found from a fit to (\pi^+)p scattering. This enable us to pinpoint condensate parameters more precisely in the context of QCD sum rules (QCDSR). In the octet sector, the Coleman-Glashow sum rule (CGSR)…
The spin structure of the nucleon is analyzed in the framework of a Lorentz-invariant formulation of baryon chiral perturbation theory. The structure functions of doubly virtual Compton scattering are calculated to one-loop accuracy (fourth…
Infinite sets of sum rules involving the excitations of infinite nuclear matter are derived using only completeness, the current algebra implicit in QCD, and relativistic covariance. The sum rules can be used for isospin-asymmetric nuclear…
The Gerasimov-Drell-Hearn and Baldin-Lapidus sum rules are evaluated in the dressed K-matrix model for photon-induced reactions on the nucleon. For the first time the sum $\alpha+\beta$ of the electric and magnetic polarisabilities and the…
We use new high statistics data from CLAS and COMPASS on the nucleon's spin structure function at low Bjorken x and low virtuality, Q^2 < 0.5 GeV^2, together with earlier measurements from the SLAC E-143, HERMES and GDH experiments to…
Measuring the spin structure of protons and neutrons tests our understanding of how they arise from quarks and gluons, the fundamental building blocks of nuclear matter. At long distances the coupling constant of the strong interaction…
Relations between differential cross section for inelastic scattering of electrons on hadrons and hadron form factors (sum rules) are derived on the basis of analytical properties of heavy photon forward Compton scattering on hadrons. Sum…
We review the status of a Fubini-Furlan-Rossetti sum rule for the photoproduction of pions from nucleons, indicating how well this sum rule is satisfied using a recent analysis of pion photoproduction data. Our results are discussed in…
Nuclear effects in polarized inelastic electron scattering off polarized $^3He$ are discussed; in the kinematics of future experiments at CEBAF, Fermi motion effects are found to be much larger than in deep inelastic scattering. It is shown…
The contribution of the $G_2$ structure function to polarized deep inelastic scattering is slightly redefined in order to avoid kinematical zeros. Its strong $Q^2$-dependence implied by the Burkhardt-Cottingham (BC) sum rule naturally…
The sum rules for the spin dependent structure function $g_1^{ab}$ in the null-plane formalism corresponding to the moment at $n=0$ has been transformed to the sum rule which relates the $g_1^{ab}$ with the cross section of the isovector…
Neutrino proton elastic scattering and polarized deep inelastic spin sum rules provide complementary information about the spin structure of the proton. We outline the two approaches and what they may teach us about the transition from…
We review the present understanding of the spin structure of protons and neutrons, the fundamental building blocks of nuclei collectively known as nucleons. The field of nucleon spin provides a critical window for testing Quantum…
The "kinematical" resolution of the $U_A(1)$ problem is proposed. The cancellation of photonic and gluonic anomalies suggested by the t'Hooft consistency principle naturally explains the zero singlet contributions to the first moments of…
An explicit evaluation of the spin asymmetry of the deuteron and the associated GDH sum rule is presented which includes photodisintegration, single and double pion and eta production as well. Photodisintegration is treated with a realistic…
The role of the $U(1)_A$ anomaly in QCD phenomenology is reviewed, focusing on the relation between quark dynamics and gluon topology. Topics covered include a generalisation of the Witten-Veneziano formula for the mass of the $\eta'$, the…
A new QCD calculation of the mass of the nucleon is presented. It makes use of a polynomial kernel in the dispersion integrals tailored to practically eliminate the contribution of the unknown 1=2+ and 1=2- continuum. This approach avoids…